####018006359#### FXUS65 KBOU 101600 AFDBOU Area Forecast Discussion National Weather Service Denver/Boulder CO 1000 AM MDT Fri May 10 2024 .KEY MESSAGES... - Showers will gradually decrease over the mountains and foothills through the day today, with snow levels around 9,000 ft. No travel impacts expected the rest of today. - Temperatures will stay below seasonal normals today. - Gradual warming this weekend and through Tuesday along with scattered showers and thunderstorms, most numerous this weekend and Tuesday onward. && .UPDATE... Issued at 959 AM MDT Fri May 10 2024 A few minor updates were made to today's forecast. First, we cancelled the winter weather advisory for the mountains because area webcams confirm roads have completely melted where snow had fallen, and where snow is actively falling (mostly southern half of Park County), the May sun angle is already significant enough to keep the roads wet. So with all mountain passes now clear, no more travel impacts are expected the rest of the day. We also updated the PoPs for today, mostly knocking them down below 6,000 ft elevation. CAMs are getting drier with each run. A look at the most recent CAMs for today shows the best chance for precip across the southern foothills and mountains (BoCo and south) and Park County. Not much accumulation is expected east of there anymore so we trimmed PoPs to 20 percent or less east of the terrain. It looks to remain dry east and north of Denver. The rest of the forecast looks on track. && .SHORT TERM /Through tonight/... Issued at 327 AM MDT Fri May 10 2024 Area radars, observations and web cameras indicated light rain showers over the southern plains and Palmer Ridge of the CWA at this time. Light to moderate snow is falling over the southwestern CWA, including Park County. Temperatures are currently in the upper 30s to mid 40s over the plains, and 30s in the foothills. Models show an upper closed low over the southern Great Basin into central Utah today with a weak upper tough axis stretched west to east across the CWA. By 12Z Saturday morning, the upper low is over northwestern Arizona with the upper trough axis across the northern border area of the CWA. QG fields have weak upward vertical velocity for much of the CWA today and tonight. The low level wind and pressure fields show weak to no upslope for the plains today. For tonight, weak drainage winds are progged. There is fairly deep moisture in place today for much of the CWA. Moisture decreases this evening and overnight in all areas. There is weak CAPE progged this is afternoon and evening, mainly over the mountains and foothills. Will keep the basic trend going with the pops in the forecast. The highest pops will be over the alpine areas and southwestern CWA this morning, with a gradual decrease through the day. There will be low to no pops over the eastern half of the plains today with "scattered" pops for the western half. Will leave the winter weather highlights going in Zones 34, 36, and 37 through 18Z today. For temperatures, today's highs look to get 1-3 C warmer over most of the CWA compared to yesterday's readings. However readings will stay below seasonal normals. && .LONG TERM /Saturday through Thursday/... Issued at 136 AM MDT Fri May 10 2024 Over the weekend, the upper-level low previously to our southwest will reverse course as building high pressure pushes it northeast into the plains, and it will weaken slightly as it does so. Thermal ridging will be more evident across the lower levels, allowing for temperatures to climb into the upper 60's for the majority of the lower elevations. Marginal instability with MLCAPE values 400 J/Kg or less and lingering mid-level moisture will sustain isolated to scattered showers/thunderstorms, most numerous in the mountains. Moisture looks more vertically consistent during the morning and early afternoon hours Sunday, so have adjusted timing of higher PoPs to reflect this. Snow levels during the weekend will generally hover around 10,000 ft during the warmer parts of the day. The ridge axis should become more prominent over the region by Monday, bringing weaker northwest flow aloft and additional warming. Temperatures will climb into the 70's for the plains and urban corridor, returning to near or slightly above normal values. QG forcing appears minimal and forecast soundings suggest a more stable profile, so showers/thunderstorm coverage should be notably more isolated, and largely confined to the higher terrain. Tuesday will start to usher in some pattern changes as a developing trough impacts the northern Rockies. Flow aloft will become more westerly/southwesterly, with increasing PWAT values. Differences in timing among ensemble guidance starts to become more significant around this time, but the overall consensus suggests an increase in thunderstorm coverage across the region. Low-level flow may still be rather subsident with drier downslope flow in the lee of the Front Range, which will help sustain warmer temperatures well into the 70's. This could ultimately taper the precipitation potential in the afternoon for areas along the I-25 corridor, with higher potential focused over the plains where instability looks to be maximized. Expect cooler temperatures Wednesday into Thursday as a cold front pushes south through the region, along with precipitation chances ticking up another notch. && .AVIATION /00Z TAFS through 00Z Friday/... Issued at 318 AM MDT Fri May 10 2024 Model cross sections show fairly low ceilings at DIA through 16Z this morning. Will go with BKN-OVC010-020. Will start to bring them up after that, expecting BKN-OVC045-050 by 21Z-00Z this afternoon. Will go with a VCSH from 17Z to 03Z this evening. Winds are progged to be pretty weak with an upslope direction much of the day. Weak drainage wind patterns should kick in around 03Z this evening. && .BOU WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...Schlatter SHORT TERM...RJK LONG TERM....Rodriguez AVIATION.....RJK ####018005755#### FXUS61 KBUF 101600 AFDBUF Area Forecast Discussion National Weather Service Buffalo NY 1200 PM EDT Fri May 10 2024 .SYNOPSIS... Unfortunately...cool and generally unsettled weather will remain in place through the weekend. Thats not to say that the next couple of days will be a washout...as there will be frequent rainfree periods as well. Daytime temperatures this weekend will be a solid 5 to 8 degrees BELOW typical mid May levels. While the mercury will TRY to get back towards normal for the first half of next week...there will still be a fair amount of showers around. && .NEAR TERM /THROUGH SATURDAY NIGHT/... Rainy weather will be in place across much of our forecast area this afternoon...particularly over the Finger Lakes region...as we will remain on the northern periphery of a poorly organized storm system over the Mid Atlantic region. Lift from this feature will be enhanced by a shortwave trough that will sag south through the region. The whole area will not be adversely impacted though...as enough dry air in the mid levels will allow for some sunshine from Niagara county to near Rochester...and also across parts of the North country. The aforementioned shortwave trough will push the weak area of low pressure further away from our region tonight...while a progressive shortwave ridge will cross the Lower Great Lakes. This scenario will be accompanied by a wedge of dry mid level air that will bring an end to the rain in most areas while promoting some clearing...mainly over the western counties. A robust shortwave and attendant sfc low will dive southeast across the Upper Great Lakes on Saturday. A swath of deep moisture ahead of this system will push across the western counties during the midday and afternoon...then across the Eastern Lake Ontario region late in the day and Saturday night. The resulting lift supplied by moderate hgt falls...low level convergence and being in the proximity of the left front quad of a nominal 90kt H25 jet with this scenario will prompt a renewal in shower activity as the day matures. There could even be a thunderstorm over the far western counties. The most widespread and persistent shower activity will be over the western counties during the afternoon. Dry weather with some sunshine can even be expected for the Finger Lakes before conditions deteriorate. It will remain cool...as temperatures on Saturday will top out within a few degrees of 60. Showery weather will then linger through much of Saturday night...as the core of a H5 low with its -24c temps will pass directly across our region. && .SHORT TERM /SUNDAY THROUGH SUNDAY NIGHT/... A mid-level trough will outrun its corresponding low-level low and move east of the region Sunday. The surface low will continue to weaken across the forecast area in the process. Unfortunately... this will lead to another cool and mostly cloudy day with low chances for light showers. Ridging and warm air advection will result in dry weather Sunday night. && .LONG TERM /MONDAY THROUGH FRIDAY/... Ridging will move into the eastern Great Lakes as another potent shortwave moves across the Central Plains Monday. A warm front will move through the forecast area and showers and a few thunderstorms are possible Monday through Monday night. Weak troughing will move into the eastern Great Lakes region Tuesday through Wednesday. A cold front will slowly cross the forecast area and unsettled conditions will persist into mid-week. There is good agreement that ridging will move into the Great Lakes region while a large area of high pressure extends from eastern Canada to the Lower Mississippi Valley Wednesday night through Thursday. Dry weather is likely across the forecast area during this time. Temperatures will average near to slightly above normal next work week. && .AVIATION /16Z FRIDAY THROUGH TUESDAY/... Areas of rain and MVFR CIGS will expand across much of the area today. Areas of IFR conditions are expected across the higher terrain of the interior Southern Tier and Finger Lakes region, including areas of fog in these same areas which may reduce VSBY down into the IFR at times as well. Exception will be toward Niagara County (KIAG) where they may escape with no lower than low VFR CIGS (3-5kft). Mainly VFR is expected toward the Saint Lawrence Valley, with low VFR CIGS (3-5kft) expected toward KART, and MVFR CIGS across the higher terrain east of Lake Ontario from late morning on. Outlook... Tonight...MVFR to VFR conditions from west to east, with lingering rain showers also ending from west to east. Saturday...VFR CIGS deteriorating to MVFR with increasing likelihood for showers. Sunday...VFR to MVFR CIGS in scattered showers. Monday and Tuesday...VFR/MVFR. A chance of showers. && .MARINE... Gentle to moderate north to northeasterly breezes (less than 15 knots) will continue on the Lakes, maintaining some light, to at times moderate chop through today. However, there are no Small Craft conditions forecast. Mainly light, variable winds (less than 10 knots) will then be the rule through the most of the weekend, before a more pronounced southwesterly flow (10-15 knots) develops ahead of a warm front approaching from the west toward the tail end of the weekend. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...None. MARINE...None. && $$ SYNOPSIS...RSH NEAR TERM...RSH SHORT TERM...HSK LONG TERM...HSK AVIATION...JM/TMA MARINE...JM/TMA ####018009817#### FXUS62 KRAH 101602 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 1205 PM EDT Fri May 10 2024 .SYNOPSIS... A cold front moving across the state today will bring a chance for showers and storms, especially south and east of the Triangle area, with severe weather possible in our southeast sections. Behind this front, mostly dry weather is expected with lower humidity and more seasonable temperatures over the weekend and into Monday. The next storm system will bring high rain chances Tuesday. && .NEAR TERM /TODAY THROUGH TONIGHT/... As of 1010 AM Friday... Forecast tweaks this morning focused on slight spatial and timing adjustments to hourly precip chances today into the evening. 12z surface analysis shows a low E off the tip of the Delmarva with a trailing trough into NE NC, a second trough (dewpoint discontinuity with shift of weak winds) along the NC Foothills into N GA, with the actual synoptic cold front still back across central and SW VA, E TN and N AL/MS. RAP-based mesoanalyses of SBCAPE and the 12z GSO sounding show well the shallow surface-based stable layer over the area (contributing to persistent stratus in our SW) with another inversion around 800 mb, topped by some decently steep (7.0-7.5 C/km) lapse rates through the mid levels that are also noted upstream. With heating expected to erode the surface stability, we're still expecting convection to develop, grow upscale and become organized into a W-E then WSW-ENE line, starting first in our SW then spreading across our SE third (where dewpoints will be around 60 or higher) through the afternoon before exiting by mid evening. A wrench in this scenario is the mature MCS to our S over SE GA and N FL. The recent CAM runs did not depict the southern bowing portion racing so far eastward, currently off the SAV coast while most models have the front edge of this complex about 150-200 m slower/ further W. This system, and its effects on the regional wind field through ageostrophic adjustments, may play into the evolution and strength of storms further N over our area, as low level jetting into our SE could be disrupted, although this actually seems less likely based on the faster MCS movement, allowing time for air mass and pressure field recovery in its wake as heating takes place. As the surface trough shifts ESE today, lower dewpoints will spread into much of the Piedmont and W Sandhills, limiting the northward extent of deep surface-rooted convection. Have adjusted pops and weather to depict lower chances of mainly just showers over the N Piedmont, transitioning to good chance to likely pops for showers and storms, some possibly strong to severe across our far S and SE, peaking in the late afternoon then shifting to our SE in the early/mid evening. Highs in the upper 70s to lower 80s. -GIH Earlier discussion from 250 AM: Low pressure is currently over southeastern Virginia with a cold front extending back to the west- southwest. There is not a huge temperature gradient along the front, but there is about a 10 degree spread in the dewpoint. The parent low will continue to head offshore, with a wave along the cold front expected to be enhanced during the daytime by an upper level shortwave. While the forecast still calls for a dry morning, have bumped up pops to likely across southeastern counties, continuing with the inherited chance pops elsewhere across the forecast area. SPC has added a slight (level 2 of 5) risk across portions of southeastern NC and northeastern SC, including portions of Scotland, Hoke, Cumberland, and Sampson counties. MUCAPE in this area should range between 500-1500 J/kg, with greatest amounts to the south. Effective bulk shear between 30-40 kt will also help to organize any thunderstorms that do develop. Although an isolated tornado cannot be ruled out, the primary severe weather threats will be damaging wind gusts and large hail. The most likely timing for severe weather appears to be between 2 and 8pm. As the front moves east by sunset, the chance for showers/thunderstorms will quickly diminish, with all rain to the east of the region by midnight. Wind gusts will pick up by late morning and continue through the overnight hours, reaching as high as 25 mph outside of any thunderstorms that develop. Highs will range from the mid 70s in the north to the mid 80s in the south. Lows will be noticeably cooler behind the front, with values ranging from the mid 40s to the mid 50s. && .SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/... As of 250 AM Friday... Today's cold front will be well offshore by Saturday morning, although a second low pressure system will be over the Great Lakes with another cold front extending to the south. The low will track east to New York by Sunday morning, and moisture with the associated cold front is not expected to track too far to the south. In fact, southern counties should remain mostly sunny through the day. Have gone with a slight chance of showers to the north of US-64 during the late afternoon and early evening, and this may be overdone. The effects of today's cold front will continue to be felt on Saturday, with some locations along the VA/NC border remaining in the upper 60s for highs and the rest of the area in the 70s. Saturday night's lows will be similar to tonight's reading, in the mid 40s to the mid 50s. && .LONG TERM /SUNDAY THROUGH THURSDAY/... As of 400 AM Friday... Dry NW flow will continue to dominate on Sunday between a mid/upper trough over the Northeast US and ridging over the lower MS Valley. At the surface, high pressure will move east from the TN Valley to become centered over the mid-Atlantic on Monday morning. This pattern will support sunny skies and another very pleasant day, as dew points are again only in the 40s. High temperatures will range from mid-70s to 80 with lows Sunday night in the upper-40s to mid- 50s, which is at or slightly below normal. The elongated surface high will move offshore into the western Atlantic on Monday and turn the flow southerly, which will help increase high temperatures back to near normal (upper-70s to lower- 80s). Meanwhile a closed mid/upper low will move from the southern Plains into the mid-MS Valley, eventually becoming more of an open wave. SW flow aloft ahead of this system will increase moisture across our region once more, with mid and high clouds spreading in from the west. The earliest we see any precipitation from this system should be Monday evening/night, as chance POPs begin to spread in (highest SW). POPs increase to likely to categorical on Tuesday and still likely on Wednesday, as the vast majority of GFS and ECMWF ensemble members depict precipitation, and the deterministic GFS, ECMWF and CMC have overall come into much better agreement on the timing of the shortwave. The system looks to move across the OH/TN Valleys on Tuesday/Tuesday night and the mid- Atlantic on Wednesday/Wednesday night. Shower and storm chances will be maximized during time of peak diurnal heating (afternoon and evening) both days. The widespread clouds and precipitation may keep temperatures down a bit on Tuesday, with highs in the 70s. Models indicate a warmer and more unstable air mass in place on Wednesday with highs in the mid-70s to lower-80s. Lows will be mild during this period, in the upper-50s to mid-60s. There will be some drying and clearing behind the shortwave early Thursday, but this will be short-lived as the next longwave trough moves into the central US and sends a shortwave the approaches our region late Thursday. Precipitation doesn't look as widespread as Tuesday/Wednesday, but isolated showers and storms still can't be ruled out. Highs will again be in the upper-70s to mid-80s. && .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/... As of 1205 PM Friday... Broken MVFR stratus persists over our southwest areas (S of INT/GSO, W of FAY), but will continue to slowly lift and break up into VFR clouds. Otherwise, INT/GSO/RDU are likely to remain VFR through much of Sat, although RDU may see a quick shower or isolated storm 21z- 00z later today. RWI will see better storm chances today, perhaps two rounds, one chance 19z-21z and again 23z-01z. Finally, FAY has the highest chance of storms, some possibly severe with damaging surface gusts and hail, 19z-01z later today. A period of sub-VFR conditions with strong/shifting winds are possible in and near any storms. But confidence is high after 03z that VFR conditions will prevail areawide, lasting through Sat. Surface winds today will be from the WSW or W shifting to NW the N from northwest to southeast with cold front passage. later today into tonight, with mostly light sustained speeds under 10 kts, but a few gusts around 20-25 kts are possible this afternoon through early evening. Looking beyond 18z Sat, VFR conditions and dry weather are expected through at least Mon, within a cooler and less humid air mass, although brief isolated showers are possible at northern terminals Sat evening. Rain and isolated storms are expected to overspread the area starting Tue morning, with a good chance of sub-VFR conditions lasting into Wed. -GIH && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Hartfield NEAR TERM...Hartfield/Green SHORT TERM...Green LONG TERM...Danco AVIATION...Hartfield ####018003957#### FXUS61 KCAR 101603 AFDCAR Area Forecast Discussion National Weather Service Caribou ME 1203 PM EDT Fri May 10 2024 .SYNOPSIS... High pressure builds across the region through Saturday night. A warm front approaches Sunday, then lifts to the north Sunday night and Monday. A storm system approaches from the west Monday night and Tuesday. && .NEAR TERM /THROUGH TONIGHT/... Update... Surface high pressure will ridge south across the region this afternoon, while upper level troffing weakens. Generally expect partly sunny/mostly cloudy skies this afternoon with diurnal cloud development. Could also have just enough support with diurnal heating and the remnants of the upper trof to support very isolated afternoon showers. However, not enough confidence to include showers in the forecast. Afternoon high temperatures will range from the mid to upper 50s, locally around 60, across the forecast area. Previous Discussion... Generally expect partly cloudy/mostly clear skies tonight. Tonight, temperatures will fall into the mid to upper 30s. && .SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... The surface level trof should keep the low pressure to the south over the waters on Saturday. RH models show the clouds building in early making for a mostly cloudy day. This with the cold pool should keep temps in the mid 50s across the region. By the afternoon, upper air model soundings show instability developing with lower CAPE values, but steep lapse rates. Nevertheless, the warm air in the mid levels and the lack of cool air to advect into the atmosphere, the chance of thunderstorms is unlikely. Scatter showers are expected through the afternoon and evening. By Saturday night, the upper level trof over the Great Lakes will slowly move E. Clouds should keep temps from in the upper 30s. By Sunday, shortwave energy from the SW is expected to move into the region bringing more moisture. The afternoon will bring more instability, but the lack of lift will only bring convective showers. By Sunday night, weak high pressure move in late to help make for partly cloud skies. && .LONG TERM /MONDAY THROUGH THURSDAY/... A developing occlusion is excepted to move across Canada with the triple point over New England on Monday and progress across the region through Tuesday. The warm sector of the occlusion and the warm front to the south is expected to bring a warming trend throughout next week. Showers are expected on Tuesday and into Wednesday. As the front moves through the area, there is a slight chance for thunderstorms on Wednesday, but lack of confidence in the timing of the track kept thunderstorms out of the forecast for the time being. High pressure should return by the end of the week. && .AVIATION /16Z FRIDAY THROUGH TUESDAY/... NEAR TERM: Generally expect VFR conditions across the region this afternoon through tonight. Very isolated showers possible this afternoon. However, MVFR conditions could begin to develop across southeast areas late tonight. Northeast/east winds 5 to 10 knots this afternoon. Light and variable winds tonight. SHORT TERM: Sat...Mainly VFR. Possible MVFR in rain showers. Light E winds. Sat night...VFR. Light ENE winds. Sun-Sun night...Mainly VFR. Possible MVFR in afternoon rain showers. Light and variable winds. Mon-Tue...MVFR in rain showers. S winds 5-15 kts. && .MARINE... NEAR TERM: Winds/seas below small craft advisory levels this afternoon through tonight. SHORT TERM: Winds and seas should remain below SCA conditions through this time period. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...None. MARINE...None. && $$ Near Term...Norcross/AStrauser Short Term...LaFlash Long Term...LaFlash Aviation...Norcross/LaFlash Marine...Norcross/LaFlash