####018005490#### FXHW60 PHFO 031859 AFDHFO Area Forecast Discussion National Weather Service Honolulu HI 859 AM HST Fri May 3 2024 .SYNOPSIS... Breezy trades will become slightly more unstable with pockets of heavier showers possible through the weekend, mainly windward and mauka. A drier moderate trade wind pattern then becomes established by the middle of next week. && .DISCUSSION... Regional satellite shows a closed upper low positioned just SE of 170N/30N. Modest convection, including a few thunderstorms, are noted within its core and beneath the cold pool aloft (-15C at 500mb) several hundred miles NW of the Hawaiian Islands. A shortwave trough wrapping around the southeast periphery of this low is currently enhancing trade wind showers where local moisture is the deepest, mainly over Windward Big Island and Maui. Otherwise, breezy trade winds have settled in and will take the edge off of afternoon heat compared the last several days as showers focus over windward and mauka zones in routine fashion. Trades will then acquire a decreasingly stable character as the aforementioned upper low opens up and shears east along the northern periphery of the subtropical jet. The inversion is modeled to weaken and lift by a few thousand feet which will increase the depth of trade wind showers as they advance across the area. This will facilitate slightly greater rain rates and increase leeward penetration of showers. Waves of forcing rotating around the low will be responsible for periodically increasing shower coverage Saturday night through early next week. During this time, the cold pool aloft will move directly overhead and is modeled to moderate to around -11C at 500mb. Lapse rates will still be adequate for pockets of deep convection to develop Sunday night through Monday night, mainly during the overnight periods. Isolated thunderstorms cannot be ruled out during this period, but confidence at this stage is too low to warrant explicit inclusion in the forecast. Meanwhile, a separate thunderstorm threat may manifest over the Big Island where a plume of steep lapse rates on the order of 7C/km is modeled to extend northeastward over the eastern end of the state. This will contribute to an increased probability of pockets of heavy showers and/or isolated thunderstorms Sunday and Monday afternoon, particularly as the upper jet provides maximum venting aloft on Sunday followed by the upper wave itself pivoting through on Monday. Confidence at this stage once again falls short of inclusion in the forecast but will be given consideration in future forecast cycles. Pressure falls over a broad swath of the Central Pacific will then ease the gradient leading to a drier moderate trade wind pattern by the middle of next week. && .AVIATION... Breezy easterly trades will continue today as high pressure builds in from the NE and pushes the surface trough NW of Kauai further away from the state. Moisture riding in on the trades will focus clouds and showers over windward and mauka areas, with the greatest shower activity during the late night and early morning hours. A few showers may spill over to leeward areas at times. VFR conditions will generally prevail, but MVFR conditions will be possible in any heavier showers that develop. AIRMET Sierra is in effect for tempo mountain obscuration for windward and mauka portions of the island chain. This AIRMET will continue for a few more hours this morning and may be needed again late tonight. AIRMET Tango is in effect for mod turb below 080 downwind of island terrain. Conditions are borderline, but should continue through the day. AMD NOT SKED in for Midway due to missing wind speed and direction && .MARINE... Latest ASCAT shows fresh to locally strong winds have arrived as a high pressure builds far north of the state. These stronger trades will continue through the weekend and drop a notch or two early next week as the high moves far northeast of the state. The Small Craft Advisory (SCA) for typical windy waters around Maui and the Big Island has been expanded to all waters through early Monday morning. Some area may drop out earlier as winds begin to ease due to the high shifting northeast. Tiny surf will persist along north and west facing shores through much of today. Forerunners of a long period northwest swell is expected to fill in this afternoon and peak Saturday, bringing small surf along north and west facing shores. Another small, long period northwest swell will fill in late Sunday, maintaining small surf along north and west facing shores into early next week. Small background south swells will continue into Saturday, providing tiny surf for south facing shores. Forerunners of a small, long period south swell may arrive Saturday afternoon with a slow onset through Sunday providing a boost in surf along south facing shores into early next week. Rough and choppy surf along east facing shores will bump up a notch Saturday and hold hold into early next week as strong trades hold. && .HFO WATCHES/WARNINGS/ADVISORIES... Small Craft Advisory until 6 AM HST Monday for all Hawaiian waters- && $$ DISCUSSION...JVC AVIATION...Farris MARINE...Vaughan ####018008030#### FXUS63 KDDC 031900 AFDDDC Area Forecast Discussion National Weather Service Dodge City KS 200 PM CDT Fri May 3 2024 ...Updated Short/Long Term... .KEY MESSAGES... - Much needed rainfall expected across much of southwest Kansas Friday night and early Saturday. Some strong to marginally severe thunderstorms are possible. - North winds and cooler air Saturday. - Severe thunderstorms are expected in Kansas Monday, with the risk of hail and tornadoes east of US 283 Monday afternoon and evening. && .SHORT TERM /THROUGH SATURDAY/... Issued at 200 PM CDT Fri May 3 2024 Midday surface observations showed moist advection well underway into SW KS, with southeast winds established, and dewpoints rising with time. Southeast winds will continue to increase through this afternoon, as surface pressures fall from SE Colorado into NW KS. With satellite imagery indicating midlevel cloud eroding quickly, temperatures will easily warm into the 70s this afternoon. With a lack of a forcing mechanism, kept the forecast dry (pops < 15%) through 7 pm. That stated, some CAMs such as 12z ARW suggests thunderstorms may be entering the far NW zones (Hamilton) around that time. Any initial thunderstorm activity Friday evening would favor the western zones, west of US 83, in a modest CAPE/shear parameter space supportive of at least marginal supercell structures. Rotating updrafts will be capable of 1-2 inch diameter hail this evening. Clearly the much richer moisture will remain locked up in West Texas through tonight, so moisture quality will be limited, keeping instability relatively muted. Still, dewpoints well into the 50s will support organized linear convection along and behind the expected strong cold front tonight. The cold front is forecast to reach the far NW zones about 10 pm, race to a DDC-LBL line by midnight, and exit the southeast CWA no later than 4 am Saturday. Most of the forcing for ascent will be post frontal, with the highly anticipated rainfall and embedded thunder occurring after the abrupt northerly wind shift. Rainfall amounts of 0.25-0.50 inch are expected to be common, but since it will only be raining 3-5 hours at any one location, amounts of up to 1 inch may be difficult to achieve. Regardless, any rainfall on our dusty parched topsoils will be welcomed with open arms. Marginally severe wind/hail (58 mph, quarters) are possible within tonight's expected line of convection, per SPC Day 1 probabilities, but modest CAPE should keep this threat muted. Outside of storms, north winds will be strong after midnight, gusting 30-40 mph. Rainfall will be wrapping up quickly from NW to SE Saturday morning, with low clouds and strong north winds. Cooler high pressure surface ridging builds in Saturday, weakening as it enters Kansas, providing a noticeably cooler day. Model guidance shows a net cooling of 6-8C at 850 mb versus Friday, with afternoon temperatures reduced to the 60s. Even with partial sunshine and diminishing northeast winds, afternoon temperatures will be 5-10 degrees below normal for early May. The process of warm/moist advection is expected to begin Saturday night and early Sunday, with light easterly winds and increasing clouds. Models have unanimously pulled back on rain production during this time, and reduced pops for Saturday night/early Sunday significantly. Temperatures will commonly be in the 40s sunrise Sunday. && .LONG TERM /SUNDAY THROUGH THURSDAY/... Issued at 200 PM CDT Fri May 3 2024 Powerful, cold midlevel cyclone near 544 dm in strength is forecast to be over Nevada midday Sunday, western Wyoming at 7 am Monday, and eject into the western Dakotas, well north of SW KS, through 7 pm Monday. Related leeside cyclogenesis/lee troughing along the I-25 corridor will accelerate southeast winds Sunday afternoon, with the strongest winds across western zones. This synoptic evolution will begin the process of dragging higher quality moisture into SW KS from the Gulf of Mexico, with dewpoints expected to reach into the lower 60s by Sunday evening. Convection potential Sunday and Sunday night looks very low, with a strong EML capping inversion and relatively cool boundary layer temperatures in the 60s and 70s keeping things rather stable despite the increasing moisture. Feel slight chance pops from the NBM this period are too high, and most locations will remain dry. Increased south/southeast winds to the 90%ile of the NBM. An intense low level jet will keep south winds strong and gusty, and temperatures elevated, Sunday night through Monday morning. Temperatures through sunrise Monday will easily hold in the 50s all zones, as dewpoints and surface moisture continue to improve. Intense trough will eject onto the plains, with an increasingly negative tilt, into NW Nebraska, through 7 pm Monday. This northern track will essentially dryslot much of SW KS, with strong SWly winds, and blowing dust and wildfire risk behind the dryline. This scenario is most preferred by 12z GFS/GEFS solutions, but as is typical, they are probably at least somewhat too progressive. 12z ECMWF/EPS members are slower with ejection, and as such are slower with the dryline's advancement into central Kansas Monday afternoon. Dryline placement will be critical for sensible weather impacts in SW KS Monday, with intense wind/dust/fire concerns west of it, and potentially high end severe potential east of it. Latest 12z ECMWF solution strongly suggests the dryline and convective initiation zone will be somewhere in the eastern DDC CWA at peak heating 4-5 pm Monday. In other words, confidence is good the severe threat will be focused east of Dodge City/US 283, but any thunderstorms that develop will be capable of hail 2-4 inches in diameter and strong tornadoes. The combination of quality moisture and jet dynamics in a strongly sheared environment suggest high end supercells are probable; the question is where do they form, and how much time they will spend in the DDC CWA. West of the dryline, southwest winds will easily gust 40-50 mph Monday afternoon, with areas of blowing dust. Wildfire danger headlines are expected along and west of US 83. Again increased winds to the 90%ile of the NBM. Included blowing dust in the grids for the western zones, and mentioned severe wording in the eastern 1/4 of the CWA Monday afternoon. No cold air advection is expected behind this system, with westerly downslope components ensuring lower to mid 80s Tuesday afternoon. From Tuesday onward, the forecast will be dry and unusually convectively quiet for May, as the moisture supply from the Gulf of Mexico will be cutoff from SW KS through at least next weekend. && .AVIATION /18Z TAFS THROUGH 18Z SATURDAY/... Issued at 1001 AM CDT Fri May 3 2024 VFR is expected to continue at all airports through at least 00z Sat. Broken mid level clouds will prevail through Friday afternoon with increasing S/SE winds, gusting to near 25 kts. A strong cold front is scheduled to sweep through the airports in the 06-09z Sat time range, accompanied by an abrupt, strong northerly wind shift, gusting to near 30 kts. Numerous rain showers and thunderstorms are expected to accompany frontal passage. Confidence was high enough to include convective TEMPO groups in this 18z set of TAFs for all airports, in this 06-09z range. Outflow winds from the strongest storms may approach 50 kts. Rain showers are expected to diminish from NW to SE through 12z Sat, with widespread MVFR stratus ceilings through Saturday morning. && .DDC WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...Turner LONG TERM...Turner AVIATION...Turner ####018009012#### FXUS63 KLOT 031900 AFDLOT Area Forecast Discussion National Weather Service Chicago/Romeoville, IL 200 PM CDT Fri May 3 2024 .KEY MESSAGES... - A dry and cool night is in store with overnight lows in the mid to upper 40s. - Tomorrow (Saturday) will be warm with highs in the upper 70s to lower 80s, and increasing chances (60 to 70%) for showers and thunderstorms in the evening especially across northern Illinois. - Periodic shower and thunderstorm chances next week, with some potential for strong to severe storms Tuesday. && .DISCUSSION... Issued at 200 PM CDT Fri May 3 2024 Through Saturday night: A surface high pressure system continues to meander through the Lower Great Lakes region and is leading to mostly sunny skies, light north to northeasterly winds, and generally pleasant temperatures (at least away from Lake Michigan). With our area on the western flank of the surface high tonight, quiet conditions will prevail. Light winds, clear skies, and a dry airmass will facilitate efficient radiational cooling and allow for overnight lows to fall into the mid to upper 40s. Tomorrow, low-level flow will turn southeasterly and eventually southwesterly as the surface high pulls further away to the east and an upper-level short-wavelength trough approaches from the west. Low- level moisture advection will allow for humid air across central Illinois and Indiana to quickly return northward and into our area by mid-afternoon. Even with filtered sunshine, the advection of a plume of seasonably warm 850mb temperatures near +13C (into which the boundary layer will build) will help boost afternoon highs into the upper 70s to lower 80s. Chances for showers and thunderstorms will increase during the afternoon hours in two apparent waves. The first will be with an axis of remnant convection (originating from the Plains tonight), due to arrive sometime in our area early tomorrow afternoon. An ensemble of CAM guidance suggests the leading axis of showers and storms may outrun the best forcing provided by the upper-level shortwave and an associated cold front lagging to the west, and fight a pocket of dry mid-level air in place across the Lower Great Lakes. As a result, chances for showers and storms appear higher later in the afternoon and toward evening along the cold front as it moves across the area (50 to 70% chance from west to east ahead of the cold front). With the upper-level shortwave and associated jet streak expected to lift northeastward toward the Upper Peninsula of Michigan (e.g. remain somewhat displaced from the instability axis further to the south across our area), any convective cell tomorrow afternoon and evening should behave in a "pulse" like fashion with overall limited storm-scale organization. As a result, the main threats with any storm tomorrow will be locally gusty winds, small hail, downpours, and lightning strikes, similar to yesterday (and consistent with a level 1/5 threat for severe weather). In all, tomorrow looks like another quintessential spring-like day. Coverage of showers and storms will decrease after sunset as the cold front approaches northwestern Indiana. Temperatures behind the front will fall into the upper 40s (northwest) to mid 50s (southeast) early Sunday morning as northwesterly winds become predominant. Borchardt Sunday through Friday: Next week is shaping up to be a fairly wet and active pattern. Starting Sunday, as an upper level low drops southward into Northern California from the Bay of Alaska (more on this later), a surface low over Hudson Bay is forecasted to continue to move east drawing the cold front east out of the forecast area. There may be some lingering showers on Sunday morning, particularly over northwest Indiana, but potentially extending as far back to I-55. However, improving and drier conditions are expected through Sunday. Temperatures are expected in the upper 60s and 70s away from the lake, but with cooler northerly air over Lake Michigan, the immediate shoreline may remain in the 50s. On Monday, the low over Northern California is expected to weaken slightly and passes over the Rocky Mountains. Ahead of of it, another upper level wave will pass over Northern Illinois. Models are disagreeing on the overall strength of the wave. The GFS is leaning deeper with an brief closed low aloft developing, where the Euro and the Canadian depict broader waves. Moisture availability seems limited though over most of the area north of I-80. With some weak lobes of vorticity that pass over, there is a chance for some light showers to pass over, but confidence remains low as it should mostly stay south of the area as temperatures warm back into the 70s, with low 60s on the shoreline. There is fairly good model agreement that the upper level low will eject out of the Rockies over west central Montana overnight Monday into Tuesday morning while deepening. Strong surface cyclogenesis is expected to take place in the Northern Plains on Tuesday; however, where and how the low develops will largely drive what unfolds on Tuesday, and models are wildly disagreeing on that. There is a strong 300 mb jet that will develop just to the south of the upper level low, with its left exit region around or just north of northeastern Illinois, which will could assist in providing additional synoptic lift, though the exact placement of the jet will have to be monitored over time. But even models are disagreeing with the strength of the jet in addition to its exact placement. Regardless, strong mid level steering flow will draw up anomalously large precipitable water values into Illinois with dew points temperatures expected in the low to mid 60s. After a weak boundary pushes through Tuesday morning providing the first chance for rain, temperatures are projected to increase behind the front into the upper 70s and 80s. With better instability, showers and thunderstorms are expected Tuesday afternoon and evening. While models are suggesting the strongest shear and instability a little farther south in Central Illinois and the Ohio River basin, there is the potential for strong to even severe storms locally on Tuesday. By Wednesday, the upper level low over the Northern Plains is projected to eventually start to weaken; however, a positively tilted trough axis will remain over Plains. With persistent southerly warm air advection, there is a risk for another round of showers and storms on Wednesday. Once again though, models are still keeping higher moisture content and stronger instability to the south over the Ohio River Valley as the jet core aloft shifts slightly over Southern Wisconsin. Perhaps the risk for stronger to severe storms will remain south of I-80 on Wednesday, but it will be close enough to be monitored. Beyond Thursday, there is much more uncertainty on exact timing of showery activity. However, both Euro and GFS ensembles are suggesting the upper level trough to continue to broaden and trudge eastward from Thursday through Sunday. With lingering moisture in the area and lobes of vorticity passing around the upper level trough, there could be periods of showers from Thursday through Saturday. It is not expected to be a complete wash out as there should be breaks from the rain at times, but it remains too far out for complete understanding on timing, so the forecast maintained a 20 to 40 percent chance for rain through Saturday morning. DK && .AVIATION /18Z TAFS THROUGH 00Z SUNDAY/... Issued at 1231 PM CDT Fri May 3 2024 - There is no impactful weather expected through the current forecast period Lingering MVFR cigs over Northwest Indiana are slowly eroding away as a cold front exits the area through the afternoon. Northeast winds around 10 knots are expected through the day, gradually rotating to the southeast by Saturday morning and diminishing slightly. Guidance is suggesting a fairly low level inversion developing Saturday morning. With enough flow above 1000 feet, it should result in a FEW low to mid level clouds developing; however, some areas in Northwest Indiana might have moments of lower vis around 4 SM, but dense fog is not expected. By Saturday afternoon, winds will become southwesterly ahead of the next passing cold front. Rain showers are expected to accompany this front, but not arriving until after the current forecast period for any of the TAF sites. DK && .LOT WATCHES/WARNINGS/ADVISORIES... IL...None. IN...None. LM...None. && $$ Visit us at weather.gov/chicago ####018009586#### FXUS61 KBOX 031900 AFDBOX Area Forecast Discussion National Weather Service Boston/Norton MA 300 PM EDT Fri May 3 2024 .SYNOPSIS... High pressure brings dry weather with cooler onshore breezes through Saturday. A slow-moving frontal boundary brings clouds and rain showers on Sunday into early Monday, along with a period of cooler high temperatures. Though clouds and off and on showers may linger in southeast New England near vicinity of the slowing front, drier weather prevails for most of interior Southern New England. Turning warmer on Tuesday with abundant sunshine, and though temperatures will be significantly cooler near the coast, interior areas could see high temperatures reach near 80 degrees. Our next chance for rain is around midweek. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... Good amount of wind shear visible on the satellite this afternoon with mid level clouds moving NE to SW and upper level cirrus moving NW to SE this afternoon. As for those mid clouds, the May sun is helping to increase our breaks of sun but partly cloudy is about the best we can hope for in much of southern New England for the rest of the day. By the overnight hours we'll see some marginal clearing of both mid and high clouds, especially after midnight, but fully clear skies aren't expected. Even so, given the high overhead and calm winds, did lower temps a but to account for some potential to radiate. Lows bottom in the low to mid 40s; right around average for early May. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/... High pressure nudges further south into New England from Nova Scotia bringing continued quiet weather for the first half of the weekend. This means continued cool, moist onshore flow from the northeast so low clouds will be moving in from the northeast while high clouds move in from the southwest. High temperatures won't be too different than Friday, with the warmest spot (the CT valley) in the upper 60s and the coolest spot (eastern MA) in the mid 50s. Cloudcover continues to increase overnight as deeper moisture (PWATs over 1 inch) move into western SNE on SW flow ahead of the approaching system. However, rain should hold off until after 8am. && .LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/... Highlights: * Cloudy, cooler with rain on Sunday into early Mon, with continued lighter showers on Mon for southeast New England. * Dry and turning mild on Tue, though cooler onshore flow near the coasts. Spot 80s in the CT Valley? * Next chance for rains around midweek (Wed/Thu), though still unclear which day has the higher rain chances. Details: Sunday and Monday: The 12z suite of guidance continues to come into better congruence regarding our next chance for steadier light rains associated with a passing frontal boundary and a rather disorganized 500 mb trough. Chances for rain increase during the morning in most areas, with the period of greatest rain chances focused during the Sunday afternoon to early Monday morning period as the frontal boundary slowly shifts eastward. With the front becoming parallel to the 500 mb flow with time as we move into the early Monday period, expect lingering rain showers during the morning hrs along the RI/MA South Coast, Cape Cod and the Islands. Further north and west, we should see dry weather but with a mix of clouds and sun. Overall not a soaking rain, but enough to likely put a damper on outdoor plans for many on Sunday, with rain showers lingering into Monday for the southeast New England coastal areas. To that end, model-ensemble probabilistic QPF assessment shows high (70-90%) probs of 24 hr rain totals over a tenth of an inch, but lower to moderate (25-50%) probs for rain amts at or over a half inch. Official forecast has rain amts around a quarter to third of an inch. Expect Sunday to be a cooler day with cloud cover and rains around, with narrower diurnal range in high and low temps. Highs Sunday in the mid 50s, and lows in the upper 40s to near 50. High temps are more challenging on Monday with more clouds south of the Mass Pike and especially near southern coast, with some sunny breaks further north. HIghs along the southern coast probably struggle to reach 60, but you don't have to go much further inland before highs reach into the low to mid 70s; with lows in the mid 40s to low 50s. Tuesday: High pressure over interior northern New England governs weather conditions into Southern New England Tuesday, supplying dry weather and mostly sunny conditions. An early look at model forecast soundings in interior MA/CT show potential for temperatures to overachieve guidance with progged deep mixing; with 850 mb temps around +7 to nearly +10C, highs could reach around 80 degrees in the CT Valley with readings well into the 70s eastward into RI and into the MA coastal plain. Northeast flow near the coast will keep temps several degrees cooler than well inland though, in the mid to upper 60s. Very difficult to show that level of granular detail given model-resolution limitations at this forecast time horizon and utilized some of the bias-corrected temperature fields given a similar regime. Did note NBM was advertising some low PoPs in this period for spot showers, but feel this is pretty overdone given progged mixing. Wednesday and Thursday: Though this period offers the next best chance for rain associated with an elongated warm front from low pressure over the Plains states, there is more uncertainty in timing when chances are greatest. Really will need those uncertainties to become more in clearer focus before delving into specifics. Didn't make too many adjustments to NBM in this period, except capped PoPs at the higher end of Chance range (40-50%) given stated timing uncertainties. && .AVIATION /19Z FRIDAY THROUGH WEDNESDAY/... Forecast Confidence Levels: Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Through 00Z...High confidence in trends, moderate in exact timing. VFR across the CT River Valley, but still working on eroding the MVFR/borderline VFR conditions across central MA/RI into eastern MA. Should see these ceilings continue to lift/scatter out by roughly 19-21Z. This should take the longest across the Cape terminals, though think ACK remains MVFR through the forecast with onshore flow. Tonight...Moderate confidence. VFR conditions to start with light and variable winds. There is a possibility for MVFR stratus to spread back in with enough onshore flow aloft. Timing wise think it would be after 06Z. Could see patchy fog across the typical prone areas in the Merrimack Valley, but have only hinted at for now. Tomorrow...Moderate confidence. Any lingering MVFR may improve to VFR for much of the day. Some uncertainty here given we are still stuck in persistent onshore easterly flow at 5-10 kts. Confidence higher for VFR away from eastern MA coastline. KBOS TAF...High confidence this afternoon. Lowers to moderate tonight. Improving to VFR by 19Z with NE to E winds. Winds light and variable tonight with enough onshore flow aloft that MVFR stratus could spread back in roughly 04-06Z. Could improve to VFR as boundary layer mixes roughly 13-15Z, but uncertain on this given the onshore wind component. KBDL TAF...High confidence. VFR through the forecast. Could see some borderline MVFR ceilings spread in 02-04Z tonight. Outlook /Saturday Night through Wednesday/... Saturday Night: Mainly VFR, with local IFR possible. Sunday: Mainly VFR, with local IFR possible. Chance SHRA. Sunday Night: MVFR/IFR conditions possible. SHRA. Monday: Mainly VFR, with local IFR possible. Slight chance SHRA. Monday Night through Tuesday: VFR. Tuesday Night: VFR. Chance SHRA. Wednesday: Mainly VFR, with local MVFR possible. Chance SHRA. && .MARINE... Forecaster Confidence Levels: Low - less than 30 percent. Medium - 30 to 60 percent. High - greater than 60 percent. Marine This evening through Saturday night... High pressure supports fairly calm conditions across the coastal waters through Saturday night. Winds will prevail out of the northeast from 10 to 15 knots with some gusts to 20 knots possible. Seas generally 1 to 3 feet. Outlook /Saturday Night through Wednesday/... Saturday Night: Winds less than 25 kt. Sunday: Winds less than 25 kt. Chance of rain showers. Sunday Night: Winds less than 25 kt. Seas locally approaching 5 ft. Rain showers likely. Monday: Winds less than 25 kt. Seas locally approaching 5 ft. Chance of rain showers. Monday Night: Winds less than 25 kt. Seas locally approaching 5 ft. Slight chance of rain showers. Tuesday: Winds less than 25 kt. Slight chance of rain showers. Tuesday Night through Wednesday: Winds less than 25 kt. Chance of rain showers. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...None. && $$ SYNOPSIS...Loconto/BW NEAR TERM...BW SHORT TERM...BW LONG TERM...Loconto AVIATION...Loconto/BW MARINE...Loconto/BW ####018007168#### FXUS66 KMFR 031901 AFDMFR Area Forecast Discussion National Weather Service Medford OR 837 AM PDT Fri May 3 2024 ...Updated AVIATION discussion... .DISCUSSION...The forecast for northern California and southern Oregon remains on track for today. An approaching low pressure system will bring rain to the Oregon coast later this afternoon, with 80-100% chances for rain over Coos, Curry, and western Douglas counties. Lesser 50-80% chances are forecast for Josephine and eastern Douglas counties through tonight. The system will move eastward through the weekend, with winter weather impacts expected over the Cascades and western Siskiyou County and Advisory-level winds for parts of Lake County on Saturday. Please see the previous discussion for more details about the short- and long-term forecasts. -TAD && .AVIATION...03/18Z TAFs...Prevailing VFR this morning will drop back to MVFR with local IFR cigs/vsbys as a potent cold front moves in, with periods of moderate to occasionally heavy precipitation this afternoon. VFR will prevail elsewhere inland through late this afternoon/early this evening. The front will spread moderate precipitation across the rest of the west side tonight, reaching east of the Cascades Saturday morning. Expect widespread MVFR conditions and local IFR in rain with higher terrain obscured in rain/snow. A rapid drop in freezing levels will occur overnight (~09-15Z) from west to east and especially around 12Z Saturday morning near the Cascades. Rain will change to snow down to as low as 2500 feet with brief heavy snow in the mountains, reducing visibility to LIFR at times. Breezy south winds are expected with the front too, with peak gusts in the 40-50 mph range. Despite the increasing winds, low level wind shear is not a concern at this time. Conditions should improve a bit behind the front with precipitation becoming more showery, but still with a good amount of MVFR ceilings/visibility through tomorrow morning. -Spilde/BPN && .MARINE...Updated 800 AM Friday, May 3, 2024...A cold front will move through today into this evening with moderate to heavy rain, gusty south winds and steep seas. Following the front, seas will remain steep, dominated by fresh short period west swell Friday night into Saturday morning. Showers continue with a slight chance of thunderstorms (20%) on Saturday. West seas trend less steep Saturday afternoon through Sunday. Another front arrives on Monday with the potential for gusty south to southwest winds followed by building west-northwest seas Monday night into Tuesday. After that, we expect high pressure to build in mid-late next week with a thermal trough strengthening along the coast. This will bring a return of stronger north winds and steep seas, highest south of Cape Blanco. -Spilde && .PREV DISCUSSION... /Issued 501 AM PDT Fri May 3 2024/ DISCUSSION...Satellite imagery is showing some marine stratus at the coast and in the Umpqua valley of Douglas County with some higher clouds beginning to move toward the coast. This is part of a more dynamic low pressure system that will be working its way through southern Oregon and northern California today into Saturday night. This low is not particularly strong, but it could bring some relatively significant precipitation to the area. Precipitation will begin at the coast and spread inland throughout the day. With the low tracking in right overhead, initial amounts may be impacted by terrain influences (specifically downsloping causing less precipitation to reach the ground for inland valleys and upsloping at the coast and coast range to increase the precipitation). However, as the low moves across the area, the terrain influences will likely be overwhelmed, and this shot of precipitation could be relatively heavy for this time of year (especially early Saturday morning). A few thunderstorms may be embedded in the precipitation on Saturday, especially with a strong cold pool aloft as evidenced by quickly lowering snow levels. In fact, snow levels will be coming down quickly from 8000 feet today to around 3000 to 3500 feet tonight. The snow levels could fall in alignment with the heavy precipitation which could facilitate a quicker changeover from rain to snow. This could lead to a period of inch per hour snowfall rates of wet snow in the Cascades and in Western Siskiyou County. Specifically, the HREF is indicating a 60 to 80 percent chance of these inch an hour snowfall rates from 4 AM to 8AM, which could lead to decent accumulations. The NBM shows a 40% chance of seeing 6 inches of snow in the Cascades Saturday night. Have issued winter weather advisories for the Cascades north of Highway 140 and Western Siskiyou County above 4000 feet (mainly for Sawyers Bar Road near Mt. Etna). Other areas may see some snow, but accumulations are not expected to be as high. In addition to the precipitation, winds will be a factor as well with this low. There will be a point where winds will largely be from the south along the front ahead of the low pressure system. Statistical guidance is suggesting 40 mph winds at Weed in the Shasta Valley on Saturday night, which is reasonable due to the decoupling of the atmosphere likely ahead of the increase in winds (which is leading to the higher precipitation rates). However, after daybreak on Saturday, the winds will pick up from the south, and could reach 50 mph. This will largely be confined to areas of Lake County, Oregon and eastward. Have issued a wind advisory for the higher elevations of Lake County including the Winter Rim and Highway 31. Showers associated with this low will linger through Saturday, although the heaviest precipitation and the gustiest winds will largely have concluded by Saturday night. Temperatures, however, will be relatively chilly and any wet roads along and east of the Cascades and in northern California may refreeze. The flow pattern becomes more zonal for Monday and another impulse will pass through the area bringing additional showers and possibly some more thunderstorms to the area. Precipitation amounts should be relatively light even if snow levels continue to hover between 3000 and 3500 feet which is unusual for May. The pattern then shifts Wednesday to a ridge of high pressure which will allow southern Oregon and northern California to warm up and dry out. This pattern will likely last into the weekend. -Schaaf && .MFR WATCHES/WARNINGS/ADVISORIES... OR...Winter Weather Advisory from 2 AM to 11 PM PDT Saturday above 4000 feet for ORZ027-028. Wind Advisory from 5 AM to 5 PM PDT Saturday for ORZ030-031. CA...Winter Weather Advisory from 2 AM to 11 AM PDT Saturday above 4000 feet for CAZ080. PACIFIC COASTAL WATERS...Small Craft Advisory until 11 AM PDT Saturday for PZZ350-356-370-376. && $$ ####018005767#### FXUS64 KHUN 031901 AFDHUN Area Forecast Discussion National Weather Service Huntsville AL 201 PM CDT Fri May 3 2024 ...New NEAR TERM, SHORT TERM... .NEAR TERM... (Tonight) Issued at 202 PM CDT Fri May 3 2024 Pop up summer like convection has begun to develop across the area with the highest coverage of scattered showers currently in NW AL. With an incredibly moist tropical air mass in place, isolated to scattered showers and thunderstorms will easily be supported through the evening ahead of the next shortwave. Higher coverage of showers and storms will move in from the SW as as the aformentioned shortwave ripples NE through the area. Higher rainfall chances look to pick up around 5 PM in NW AL and around 8 PM in NE AL. Uncertainty remains in coverage of showers and storms as the shortwave moves through. What seems likely at this point is a cluster of scattered rain and storms moving into NW AL and continuing east throughout the night. CAMS continue to diverge on solutions with the passage of the shortwave with some models showing widespread light to moderate rain and others showing corridors of heavier rain for same and dry conditions for others. With such a moist boundary layer and a few hundred J/KG of CAPE all storms will be capable of producing frequent lightning and heavy downpours. Areas that do see better storm coverage will likely see high convective rainfall rates that could produce ponding of water and localized nuisance flooding in urban and flood prone areas. The shortwave and associated showers and storms looks to move out in the early morning hours with low rain chances lingering into Saturday. && .SHORT TERM... (Saturday through Monday) Issued at 202 PM CDT Fri May 3 2024 Saturday, and the remainder of the short term, offers the same forecast challenges. A weak syntopic pattern remains in place with broad mid level ridging to our east allowing for subsequent shortwaves to ripple through the area. The passage of a shortwave tomorrow afternoon will again trigger our highest chances and highest coverage of rain and storms. Once again, tricky pop up convection remains a possibility starting in the late morning ahead of the shortwave. This pattern continues on Sunday into Monday as a mid level trough in the Plains pushes at least two more shortwaves through the area. This will maintain medium to high PoPs across the CWA with highest coverage of rain and storms reserved for each afternoon. While each day will pose a threat for frequent lightning and heavy rainfall, no severe weather is anticipated through the duration of the short term. As for anticipated rainfall, overall weekend QPF amounts will likely vary greatly in spatial coverage. With favorable environmental factors in place for efficient rainfall production, showers could easily dump a quarter to a half inch in a brief period of time for isolated areas. While this alone is not enough to raise flooding concerns, periods of heavy rainfall could continue to trigger ponding of water and nuisance flooding for urban area. When it's not raining, the tropical airmass will make for a very humid weekend. Highs remain in the low 80s with dewpoints in the high 60s each day. && .LONG TERM... (Monday through Thursday) Issued at 433 AM CDT Fri May 3 2024 After warm frontal convection spreads northeastward and out of the region late Monday morning, the TN Valley will be solidly within a very warm/moist tropical airmass, with dewpoints expected to rise into the m-u 60s as southwesterly low-level flow strengthens. Although this will contribute to greater instability (especially during the afternoon hours), a mid-level ridge will shift across the region downstream from the central Rockies upper low as it begins to spread northeastward into the northern Plains, and this should yield a lower coverage of mainly afternoon thunderstorms from Monday-Wednesday. Overnight lows will steadily increase into the u60s-l70s through the middle of next week (due to both elevated SW winds and moisture advection), with highs also warming into the mid (to perhaps upper) 80s by Wednesday. Although details are unclear at this time range, conditions will become more favorable for convection at the end of the extended period (Wednesday night/Thursday), perhaps in the form of MCS activity that may initiate along a cold front to our northwest and propagate southeastward into the local area. Should this scenario materialize, conditions will be favorable for organized severe thunderstorms across our region, with boundary layer dewpoints in the u60s-l70s beneath a belt of mid-level WSW flow of 35-45 knots. && .AVIATION... (18Z TAFS) Issued at 1230 PM CDT Fri May 3 2024 Afternoon pop up convection will make for challenging TAFs. Scattered showers and thunderstorms are likely to develop through the afternoon from surface heating. Kept VCTS in the prevailing to account for uncertainty in storm coverage and intensity. Later this evening, just before 0Z, more widespread showers and storms will move in from the west. This will result in heavier showers with periods of MVFR to IFR possible as reflected in the tempo group. While strongest showers and storms will move out of the area during the early morning hours, MVFR ceilings will likely remain for the duration of the TAF period. && .HUN WATCHES/WARNINGS/ADVISORIES... AL...None. TN...None. && $$ NEAR TERM...RAD SHORT TERM....RAD LONG TERM....70 AVIATION...RAD ####018011160#### FXUS63 KIND 031902 AFDIND Area Forecast Discussion National Weather Service Indianapolis IN 302 PM EDT Fri May 3 2024 .KEY MESSAGES... - Potential for patchy fog and low clouds late tonight and early Saturday. - Isolated to scattered showers and storms through this evening then again on Saturday. - Multiple chances for showers and storms throughout most of the forecast period, with continued above normal temperatures. - Potential for severe weather during the middle of next week, highest chances Tuesday evening and Wednesday night. && .SHORT TERM (This evening through Saturday)... Issued at 256 PM EDT Fri May 3 2024 Damp and mainly cloudy afternoon in progress across the forecast area as a diffuse frontal boundary lingers over the southeast half of central Indiana. Have seen some breaks in the lower stratocu develop behind the boundary but tend to fill right back in with an abundance of low level moisture lingering. Scattered showers have redeveloped over southeast counties over the last hour or two. 18Z temperatures ranged from the upper 60s to mid 70s. Today marks the beginning of a more unsettled regime setting up over the Ohio Valley for the next several days and not expected to reach its zenith until the early to middle part of next week. However the presence of lingering low level moisture at least across parts of the region and the remnant boundary likely to settle near the Ohio River tonight will bring at least a periodic threat for isolated to scattered convection through late day Saturday and eventually beyond. Through Tonight Expect any isolated showers or thunder will focus in the vicinity of the boundary and deepest portion of the moisture plume...focused across the southeast half of the forecast area. The current ACARS sounding highlights weak instability levels that have increased slightly courtesy of diurnal heating despite the clouds. It should be noted however that the actual primary windshift and dewpoint boundary lags back to the northwest from the front...and that could aid in additional isolated development early this evening focused back near the I-70 corridor. Will hold onto isolated pops for a short period as far northwest as a Terre Haute-Indy Metro-Muncie line as a result. Could certainly see a few rumbles of thunder but overall any convection over the next few hours will be disorganized and weak in the absence of little if any BL shear and light winds through the lower levels. Broad area of clear skies and dry air noted on current satellite imagery this afternoon back across Wisconsin and northern Illinois associated with a high pressure ridge. This feature will drift east into the Great Lakes tonight and while the bulk of the subsidence and dry air will remain to the north of the forecast area...this will sway enough influence locally to allow for clearing skies late tonight focused across the northern Wabash Valley. Further south across the forecast area...the dewpoint boundary will shift south a bit before stalling overnight with much of the forecast area south of I-70 remaining at 60 degree dewpoints or higher. While any threat for a shower is minimal overnight considering little forcing aloft and negligible instability...the presence of the deeper moisture will keep the potential for lower stratus across the southern half of the forecast area and may also bring patchy fog into play prior to daybreak. While the air will be slightly drier in northwest counties...there is an increased potential for some fog formation in these areas as well with skies set to clear late. Saturday The aforementioned surface ridge will move northeast away from the Great Lakes on Saturday...leaving a residual axis of drier air extending southwest from lower Michigan into eastern Missouri. This will be slowly gobbled up through the course of the day between the deeper moisture plume focused across the Ohio Valley and our southern counties and a frontal boundary tracking through the Missouri Valley. The veering of low level winds to easterly and eventually southeasterly by the afternoon will enable the deeper moisture to advance back to the northwest across central Indiana and interact with an increasingly unstable airmass as CAPE values climb to 1000-2000 j/kg. While overall forcing aloft and shear remain weak...the combination of the instability and moisture will be enough to generate scattered convection again on Saturday with the best focus once again over the southeast half of the forecast area. Storms will be of pulse intensity and may see a few stronger cells that can throw out localized higher wind gusts. Otherwise... lightning and brief/localized heavy rainfall will be the primary impacts to outdoor activities on Saturday from any convection. Temps...lows will fall back into the middle 50s tonight across the northern Wabash Valley but most of the rest of the forecast area will remain closer to 60. Low level thermals support highs rising into the upper 70s and lower 80s across much of central Indiana Saturday with the warmest reading likely to be across western portions of the forecast area where convective coverage will be lower and more sunshine will be realized. && .LONG TERM (Saturday night through Friday)... Issued at 256 PM EDT Fri May 3 2024 We're looking at a fairly active long range with precipitation chances nearly every day. Severe weather is not expected through the weekend, though this may change by early to mid next week. SYNOPTIC OVERVIEW The upper-level flow pattern across North America is rather simple. A long ridge axis stretches up the eastern seaboard and a broad trough exists over the northern Plains. Along the Mexican border, a zonal but fairly fast subtropical jet extends into the Gulf. Further west, over the Pacific Ocean, another trough can be found diving southward out of the Gulf of Alaska. It's this Pacific trough that may become the driving factor for active weather next week. Through the weekend, however, we'll be dealing with occasional showers and thunderstorms as a few impulses aloft pass by. The first, covered in the short term, is more a part of the northern jet while a second lifts northeast from the subtropical jet Sunday into Monday. With no strong push of continental air, a warm and buoyant air mass is likely to be in place through the weekend and into next week. As such, any system passing by should have access to enough instability for convective precipitation. In fact, model soundings Sunday-Monday show essentially a moist adiabatic profile. Low LCLs with high freezing levels may promote more contribution from warm rain processes. Available moisture is high (PWAT over 1.5 inches) and deep, so rainfall may be quite efficient at times. This of course depends on how much forcing there is for convection, and some model uncertainty remains regarding where exactly the vort max tracks. By Monday afternoon, the Pacific trough should be ejecting into the Plains in a highly amplified manner. Guidance shows the trough occluding quickly, with upper-level flow regaining a more zonal orientation Tuesday and Wednesday. The occluded low meanders over the northern Plains for a few days, with vort maxes occasionally rotating around and progressing eastward over the Midwest. Guidance is in good agreement regarding the larger-scale pattern but disagrees with the smaller features (vort maxes). The placement and timing of these vort maxes may play a critical role determining severe potential Tuesday and Wednesday. FORECAST CONFIDENCE COnfidence is good with the large-scale pattern, but decreases with regards to sensible weather. The primary driver of this uncertainty is variations in track/timing of various vort maxes. Additionally, convective regimes can have a cascading affect on subsequent convective evolution...so uncertainty can be high even if the larger- scale pattern is more certain. That being said, a few things can still be said about our potential for severe weather / flooding next week. As mentioned before, ensemble guidance is in good agreement with the larger pattern. Additionally, NAEFS/ECMWF situational awareness tables show anomalous moisture through this weekend and much of next week. Deterministic guidance, while showing more disagreement between individual models, is still useful in visualizing how this moisture interacts with passing waves. Periodic surges of richer/deeper moisture advect northward ahead of each wave, signifying potential for heavy rainfall in addition to severe weather through the period. Regarding severe weather, CSU machine learning and CIPS analogs have been honing in on the Tuesday-Wednesday period over our region. It remains a rather broad area, and favorable synoptic conditions (Occasional synoptic forcing, instability, shear) add confidence to these signals. It's difficult to downscale things any further at this range since the final outcome will likely rely on features not yet resolvable. Still, the potential exists for severe weather along with heavy rainfall next week. Stay tuned for updates. && .AVIATION (18Z TAF Issuance)... Issued at 100 PM EDT Fri May 3 2024 Impacts: - Isolated showers and thunderstorms through early evening - Fog possible overnight but depends upon how much MVFR stratus lingers/expands late tonight and early Saturday Discussion: Low stratus persists in spots early this afternoon but some breaks in the cloud deck have developed as well. Increasingly diffuse frontal boundary draped across the region with higher dewpoint air persisting over the southeast half of central Indiana will support isolated convective development through the remainder of the afternoon and into the evening. The only terminals that is likely to be free from any potential rain is KLAF as drier air is already expanding into the northern Wabash Valley. Winds will eventually align to N/NE overnight as the remnant frontal boundary settles near the Ohio River. Low level RH progs and model soundings show plenty of leftover moisture within the boundary layer that may expand back to the northwest towards daybreak Saturday as low level winds veer to a more easterly direction. The potential for fog will be dependent on the degree of clearing which remains uncertain as there are hints that MVFR level stratus will encompass the terminals near daybreak. Winds will veer further to southeast on Saturday with lower clouds gradually decreasing in coverage. && .IND WATCHES/WARNINGS/ADVISORIES...None. && $$ SHORT TERM...Ryan LONG TERM...Eckhoff AVIATION...Ryan