####018003355#### FXUS66 KHNX 032230 AFDHNX Area Forecast Discussion National Weather Service Hanford CA 330 PM PDT Fri May 3 2024 && .KEY MESSAGES... 1. The ongoing warming trend will continue today with daytime highs rising to 4 to 7 degrees above normal. 2. The Winter Weather Advisory has been upgraded to a Winter Storm Warning due to an increase in expected snowfall, with 5 to 10 inches of snow expected above 5,000 feet and 12 to 18 inches above 7,000 feet. The highest elevations above 9,000 feet are expected to see 1 to 2 feet of snow. 3. High temperatures are forecast to cool to around 10 to 15 degrees below normal by Sunday. 4. Dry weather and a warming trend will take place Monday through Friday. && .DISCUSSION... A small ridge set up over California will lead to the continuation of the warming trend that has lasted throughout the week, with highs today 4 to 7 degrees above normal. This will come to an end as a late season storm system is expected to impact Central California tomorrow. A trough aloft is expected to drop down south and bring with it a low pressure system with a strong cold front that will sweep through the area. This will lead to periods of light to moderate rainfall for the valley and the Sierra Nevada foothills, and heavy snow for the Sierra Nevada mountains above 5,000 feet. Travel will be very difficult in these areas beginning Saturday morning. The Winter Weather Advisory for the Sierra Nevada has been upgraded to a Winter Storm Warning due to the increase in expected snowfall. It will be valid from 11 AM Saturday through 8 AM Sunday. Total snowfall accumulations of 5 to 10 inches are expected above 5,000 feet and 12 to 18 inches are expected above 7,000 feet. The highest elevations, above 9,000 feet, are expected to see 1 to 2 feet. The cold front will come through Saturday morning, which will lead to afternoon highs that day and Sunday to drop to 10 to 15 degrees below seasonal norms. The system will exit the area by early Sunday morning, with ridge-building beginning right after. This ridge will lead to dry weather and a warming trend for the next week, leading to temperatures by next Friday increasing into around 7 to 10 degrees above seasonal norms. Long term ensemble models show the ridge will continue to sit over the western portion of the CONUS through next weekend and into the following week. && .AVIATION...VFR conditions will prevail across the central CA interior for at least the next 24 hours. && .AIR QUALITY ISSUES... ISSUED: 05/02/2024 15:17 EXPIRES: 05/03/2024 23:59 None. && .CERTAINTY... The level of certainty for days 1 and 2 is medium. The level of certainty for days 3 through 7 is medium. Certainty levels include low...medium...and high. Please visit www.weather.gov/hnx/certainty.html for additional information and/or to provide feedback. && .HNX WATCHES/WARNINGS/ADVISORIES... Winter Storm Warning above 5000 feet from 11 AM Saturday to 8 AM PDT Sunday for CAZ323-326. Winter Storm Warning above 5000 feet from 2 PM Saturday to 8 AM PDT Sunday for CAZ327>330. && $$ Public/Aviation/Fire Weather............EW weather.gov/hanford ####018009197#### FXUS65 KREV 032231 AFDREV Area Forecast Discussion National Weather Service Reno NV 331 PM PDT Fri May 3 2024 .SYNOPSIS... Warmer temperatures continue today, with light winds. Active weather returns tomorrow with a storm system bringing gusty to strong winds along with valley rain and mountain snow, with conditions slowly improving Sunday. For next week, a slow warming trend with low chances for precipitation remains in the forecast. && .DISCUSSION... REST OF TODAY: The latest RAP analysis shows the CWA underneath a weak upper air ridge this afternoon with a pretty robust upper air low residing over the Pacific Ocean west of the U.S./Canada border. Current surface observations report back mostly light and variable winds with a few breezy gusts out of the east in some some locations. Model guidance then forecasts the low to move southeast towards the U.S. coast going into the night and pushing the ridge to the east. At the surface, daytime high temperatures expect to be in the 60s to the lower 70s with cooler highs in the Sierra Crest. While most of the region expects to stay dry, the HREF shows a 10- 20% probability for an isolated shower or two later this afternoon/evening in Mono County and the bordering areas though not much moisture is expected with these showers. THE WEEKEND STORM: Forecast guidance projects the upper air low continuing a progression towards the CWA throughout Saturday and then passing over the northern portion of the CWA on Saturday Night and going into Sunday morning. By late Sunday evening, the low is expected to have moved east of the CWA allowing for a north- northwesterly flow over the CWA going through the night. With this upper air pattern, a low pressure system looks to move east- southeastward across OR on Saturday and make its way over northern UT by Sunday morning. This will cause a quick moving cold front to begin to sweep across the CWA on early Saturday morning. This front will cause the region to see two impactful weather concerns for Saturday: gusty to strong southwesterly winds along with winter-like precipitation including accumulating mountain snow and valley rain. * Winds: Upon looking at the latest ECMWF EFI (Extreme Forecast Index) for wind gusts on Saturday, there is a "bulls-eye" of 0.90- 0.99 values in southern portions of the region (southern Lyon, Mineral, and Mono counties) that slowly lowers going northward into the CWA. There is a second maximum seen in northern Washoe county as well of 0.8-0.9. What this means is that there is a really good signal for strong (~60+ mph) wind gusts within the region on Saturday. Please refer to the High Wind Warning as well as the Wind Advisories for more detailed information on expected maximum gust values as well as locations. There is also information on strong winds contained within the Winter Weather Advisory and Winter Storm Warning that should be referenced as well. These winds will cause hazardous conditions including potential blowing dust during beginning on Saturday morning and going into the evening. Travelers are recommended to check conditions within the region be embarking on their journeys. The winds look to decrease a bit by late Saturday night/early Sunday morning as the system moves more eastward away from the CWA. * Snow and Rain: With the latest QPF updates, snow totals particularly for the Sierra Crest and Tahoe Basin have come up a bit on Saturday and going into Sunday. As a result, the Winter Weather Advisory on Saturday and Sunday for the Lake Tahoe Area and Mono County has been upgraded to the first ever NWS Reno Winter Storm Warning issued for the month of May in recent history. Lassen, Eastern Sierra and Eastern Plumas counties remain in the Winter Weather Advisory Please refer to the Winter Weather Advisory and the Winter Storm Warning for more details such as timing, locations, and forecast snowfall amounts for the these areas above 5000 feet. Weather.gov/rev/winter also is a source for this information along with the latest Winter Storm Severity Index (WSSI) which shows moderate to major impacts along the Sierra Crest and some of the mountain passes. The latest HREF is showing the potential for 1-2 inch per hour snowfall rates which is not very common this time of year. Once again, travelers should be prepared due to expected hazardous traveling conditions in these areas that will include blowing snow (with the strong winds) and accumulating snow that may cause slick roadways. While the higher elevations see good snowfall chances, lower elevations particularly in the valleys will see rain more as their P-type though some areas may see some snow mixed in on Saturday night with temperatures cooling and snow levels dropping. Snow flurries may be possible going into Sunday morning within western NV. The latest QPF values range from around a trace in Mineral county to around almost 2 inches in the Sierra Crest on Saturday and Sunday. Precipitation chances look to begin Saturday morning in the west with the front approaching and spread through the rest of the CWA by the afternoon hours. These chances then look to depart out the east with the system by late Sunday afternoon allowing for a drier evening and night. * Temperatures: Temperatures do come crashing down and are pretty cold for May standards on Saturday and especially Sunday due to the cold front passage. High temperatures will be upwards of 15-20 degrees below average, as the region barely reaches 40 degrees for Sierra communities with western NV seeing lows as high as the low to middle 50s. There is additionally the chance for sub-freezing temperatures in western NV and northeast CA on Sunday and Sunday night into Monday morning. BEYOND THE WEEKEND: Model guidance shows the upper air low opening up into more of a negatively tilted trough on Monday over the Rocky Mountains allowing for a mostly northwesterly flow over the CWA that continues through Tuesday. It also continues into Wednesday with the trough becoming more neutral over the central CONUS as a ridge moves over the Pacific Coast. As a result, temperatures look to rebound a bit though still being cooler on Monday before slightly cooling on Tuesday with a warming trend beginning on Wednesday. While the upper air pattern is unsettled at this time, signals do point to the warming trend continuing through Thursday and Friday. Precipitation chances look to be minimal at best currently during the next work week. There may be some fog concerns during the morning hours around the Truckee area during mornings to begin the work week, so will continue to monitor this potential. -078 && .AVIATION... * Friday will feature pleasant flying conditions with light winds and mostly clear skies into the evening. There are a few showers around KMMH into the eastern Sierra that will quickly dissipate after sundown this evening. Weekend Storm Update: A strong, unseasonably colder spring storm system is moving into the region overnight tonight through Saturday. * Snow/Rain: Widespread mountain snow showers and valley rains are likely (>70-90%) overnight into Saturday evening throughout the northeast CA, the Sierra, and western NV. This colder airmass will allow for snow levels to drop to 5000-5500 feet by Saturday night. Sierra terminals KTRK, KTVL, and KMMH could see between 3-5" of snowfall with a 80-90% chance for at least 2". However, high sun angle in May may limit accumulations on runways at those terminal during the day. There is also a slight chance for snow flurries Saturday night into Sunday morning for far western NV terminals (KRTS-KRNO-KCXP-KMEV). * Winds: Strong west to southwest winds will increase across the Sierra overnight and continue through Saturday night. Look for sustained ridgetop winds across the Sierra of 40-50kts with gusts upwards of 70-90kts during this time period. Expect periods of mountain wave turbulence, as well as LLWS for all area terminals. Strong west to southwest winds are possible as well for all western NV and Sierra terminals through Saturday. -Amanda && .REV Watches/Warnings/Advisories... NV...Wind Advisory from 8 AM to 5 PM PDT Saturday NVZ005. Winter Storm Warning from 11 AM Saturday to 8 AM PDT Sunday NVZ002. High Wind Warning from 8 AM to 8 PM PDT Saturday NVZ001-003. Lake Wind Advisory from 8 AM to 8 PM PDT Saturday NVZ004. CA...Wind Advisory from 8 AM to 5 PM PDT Saturday CAZ070. Winter Weather Advisory from 11 AM Saturday to 8 AM PDT Sunday CAZ071. Winter Storm Warning from 11 AM Saturday to 8 AM PDT Sunday CAZ072-073. && $$ ####018007668#### FXUS61 KPHI 032231 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 631 PM EDT Fri May 3 2024 .SYNOPSIS... High pressure over New England will maintain an onshore flow through the next few days. A series of cold fronts approaches from the west through the weekend, with the second (and stronger of the two) front stalling out nearby by early next week. The stalled front lifts north as a warm front at some point in the Tuesday/Wednesday timeframe, bringing a return to above normal temperatures. && .NEAR TERM /THROUGH SATURDAY/... 6:30PM...The current forecast continues to remain challenging due to pesky marine layer over the Coastal Plain. An expansive ridge of high pressure is building into eastern Canada with the southwestward periphery of this feature extending back into the Mid-Atlantic. In fact guidance actually depicts this feature strengthening slightly over our area during the next 24 hours. Meanwhile though, this ridge has resulted in easterly flow that has brought in a low deck of some marine stratus into much of NJ, DE, and even extending at times into portions of eastern PA. Finally, there is a frontal system that's approaching from the west with some showers however, it will take some time for these showers to get into the area over the weekend as it runs up against the ridge in place. The upshot of all this is that skies are variable across the area with the marine stratus eroding back to the east while high cirrus continues over western areas. Regardless, it will remain precip free though through the evening. Overnight, however, shortwave energy will ride over the top of the upper level ridge centered over the east and help to push showers from the west closer to the region. This could bring a few light showers into parts of Delmarva and eastern PA by daybreak. Otherwise, clouds thicken through the night with lows getting down mainly into the upper 40s to around 50. For Saturday, low pressure moves eastward towards the Great Lakes driven by an advancing upper level trough. As this occurs, showers well ahead of it will continuing to try making inroads into our area while running up against the stubborn surface high that will be slow to move out. The upshot is some scattered showers will likely make it in at times, especially over eastern PA and Delmarva and especially getting into the second half of the day (POPs here by late day generally 40 to 60 percent). Otherwise it will be a mostly cloudy and cool day with continuing easterly winds and highs only making it to the upper 50s to low 60s. && .SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/... Saturday night will featured continued marine flow from the east as the approaching front from the west washes out. Thus, expect areas near the coast to be mostly dry and cool, with a better chance of showers inland due to the nearby stalled front. Lows mostly in the upper 40s. Next, stronger front approaches from the west Sunday, but its approach looks slower, so have slowed the progress of higher POPs into the area. Looks like best chance of widespread showers is late day and at night Sunday night. With the marine layer likely to hold fairly firm, chance of thunder looks minimal, and severe weather risk appears zero. Highs 50s north, 60s south, perhaps near 70 far southern DE and adjacent parts of MD. Rain showers move out on Monday morning, though again opted for slower timing given trend. Marine layer looks like it is at least somewhat disrupted as flow turns westerly and a warm front tries to lift north, allowing temps to potentially rise to the 70s for most and near 80 southern DE/adjacent MD. Guidance now wants to generate some convection in the afternoon, and given the warmer and more humid air mass, its not out of the question we have a few stronger cells, but at this point there doesn't appear to be a significant severe wx or flood risk. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... Unsettled weather continues through the week ahead. The front that lifts north thru the area Monday doesn't get far, and looks to even slide back south a little Tuesday, though at this point still looks likely mostly 70s. Another approaching shortwave and proximity of the front could spark off a shower or t-storm, but right now looks like low coverage. Front lifts a little further north behind that shortwave Wednesday, allowing temps to rise a bit. With it remaining nearby and another front approaching from the north, the odds of some aft/eve convection increases a bit. Highs closer to 80. Guidance is trending towards the return of a marine layer behind said front for Thursday and Friday, with a cooling trend in temps. A passing wave may produce some better shower coverage Thursday as well, so we have highest POPs in the long term on Thursday. Friday trend is a little drier but still a marine influence. It should be noted that with the wavering front nearby all week and several weak waves, its possible the details of the forecast are notably different from how they currently appear, so check back for updates frequently. Guidance is very mixed presently. && .AVIATION /00Z SATURDAY THROUGH WEDNESDAY/... The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. Through this afternoon...Mainly MVFR predominating at ACY, MIV, TTN, and PNE due to low stratus. Otherwise mainly VFR with a scattered deck around 2500 feet. East winds 10 to 15 knots with some gusts to around 20 knots possible. Moderate confidence. Tonight...The marine stratus should result in MVFR cigs or lower eventually predominating by the overnight period with conditions lowering through the evening around PHL but likely not until the overnight at RDG and ABE. IFR cigs likely overnight at MIV and ACY. East winds 5 to 10 kt. Low confidence. Saturday...Mainly MVFR in the morning with some improvement in the afternoon to VFR except at MIV and ACY where MVFR may continue. East winds around 10 knots. Low confidence. Outlook... Saturday Night through Sunday Night...Restrictions expected with showers moving through, with CIGs as low as IFR possible. Best chance of showers is late Sunday/Sunday night. Monday through Wednesday...Primarily VFR though some restrictions possible with any showers. 20-40% chance of showers through this period. && .MARINE... The Small Craft Advisory has been extended for the ocean zones from Great Egg Inlet to Fenwick Island until 10 PM due to seas around 5-6 feet. These conditions should continue to diminish early this evening with seas diminishing to 10 to 15 knots and seas around 3 to 4 feet. Little change is expected on Saturday. It will also be mainly cloudy over the waters through Saturday with some patchy fog possible at times. Outlook... Saturday night through Wednesday...No marine headlines anticipated. Showers/thunderstorms possible on the waters Sunday through Sunday night. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...None. NJ...None. DE...None. MD...None. MARINE...Small Craft Advisory until 10 PM EDT this evening for ANZ453>455. && $$ SYNOPSIS...Fitzsimmons/Hoeflich/RCM NEAR TERM...DeSilva/Fitzsimmons/MPS SHORT TERM...RCM LONG TERM...RCM AVIATION...Fitzsimmons/MPS/RCM MARINE...DeSilva/Fitzsimmons/MPS/RCM ####018006488#### FXUS63 KMQT 032232 AFDMQT Area Forecast Discussion National Weather Service Marquette MI 632 PM EDT Fri May 3 2024 .KEY MESSAGES... -The UP remains under the preferred path for low pressure systems, with multiple notable features passing through the next week. -In between systems, dry conditions will be expected, though mostly low winds and preceding rainfall should broadly limit fire concerns. && .SHORT TERM /THROUGH TONIGHT/... Issued at 139 PM EDT Fri May 3 2024 Calmer weather is being seen this afternoon as the last of the cloud cover has lifted away from the far east. With sunny skies being overhead the rest of this afternoon and with subtle warm air advection continuing, highs today could get into the mid 60s to low 70s before this evening; some spots, including Watson, Marquette, and L'Anse, have gotten to 68F already. Otherwise, gusty WSW'rly winds across the western half continue the rest of this afternoon before dying down this evening as deep mixing takes place across our region. Moving into tonight, cloud cover looks to return to the west half late as another low pressure system from the Central Plains looks to lift towards the U.P.. As it does so, we could see a few sprinkles late tonight from time to time across the west. Therefore, while skies will be mostly clear for tonight, the western half's low temperatures tonight will be a few degrees warmer due to the incoming cloud cover; temperatures are expected to get down to the mid 40s near Lake Superior, the low 40s over the western interior, and upper 30s in the interior east tonight. && .LONG TERM /SATURDAY THROUGH FRIDAY/... Issued at 334 PM EDT Fri May 3 2024 Saturday morning, while troughing is based over far northern Ontario, a trailing shortwave trough will be passing through the Dakotas and will support a weak surface low. 12Z GEFS pressure centers suggest a 1005-1010mb surface low passing over central Lake Michigan late Saturday. Ahead of the low, rain chances spread across the western UP during the morning hours. This will keeps high temps cooler (around 60F) compared to the central and especially the east where highs approaching 70F are forecast. The cool front and associated rain chances spread across the central and eastern UP during the afternoon and evening, respectively. While this does line up with peak diurnal heating, 12Z HREF mean MUCAPE only maxes out in the 100-250 J/kg range in the south and east, though simulated reflectivity does show some convective potential, so some slight thunder chances are left in the forecast for the evening hours, though impacts should be low. The convective nature of later showers biases the ensemble max rainfall, but the mean rainfall around a tenth of an inch (0.1 in) across the UP is a more reasonable forecast given meager instability and lack of training. The exception will be in the east, where the HREF shows over 50% probabilities of 6-hourly rain rates over 0.25 inches and 30-40% chances of total rainfall over a half inch. In the wake of the low, 500mb heights begin to rise Sunday, supporting a 1020mb high pressure settling over the UP through late Monday. This will give the UP as a whole its driest stretch of the last few weeks with high confidence of no precip through at least early Tuesday morning. The main forecast concern will be how dry the airmass gets for Sunday and Monday, as efficient mixing and radiative heating under clear skies will allow RHs to fall. Going with the 10th percentile of Td guidance Sunday and Monday results in RHs falling into the 30s, though with the recent precipitation and light winds directly under high pressure, fire weather concerns should be tempered. A bowling ball closed 500mb low will be passing through the Rockies Sunday into Monday, negatively tilting as it does. This will support strong lee cyclogenesis, with the 12Z GEFS showing a mid 970s-upper 980s mb low over the Northern Great Plains. While confidence is increasing that severe weather much further south will result from this low progressing eastward, ensemble spread is high in the track, timing, and strength of this low pressure Tuesday and beyond. Late Tuesday has the highest chances of rain, with the NBM showing 50-80% PoPs during that time, but whether the low quickly ejects out or stalls is still unknown, so lower PoPs remain through the remainder of the forecast. With the cold-core nature of the system, the chances of embedded thunderstorms this far north will rely on some diurnal influences, but the strength of said storms is quite uncertain at this time. && .AVIATION /00Z TAFS THROUGH 00Z SUNDAY/... Issued at 631 PM EDT Fri May 3 2024 VFR conditions continue through most of the TAF period as weak ridging moves over us. Starting late tonight, another low pressure currently over the Central Plains lifts northeastward towards the Upper Midwest and brings more rainfall to the west as soon as Saturday afternoon. This incoming rainfall could bring MVFR and possibly lower conditions back across KIWD, MCMX and KSAW by the end of the TAF period. && .MARINE... Issued at 334 PM EDT Fri May 3 2024 Wind flow is split over Lake Superior, with the west half seeing SW winds up to 25 knots and the east half seeing winds less than 20 knots out of the SSE. Gusts lakewide fall below 20 kt tonight. As a weak low pressure passes through the Upper Great Lakes Saturday, the eastern portions of Lake Superior could briefly see some NW wind gusts up to 25 kt Saturday night into Sunday morning. As high pressure settles over the lake Sunday and Monday, winds will be below 20 kt until Monday afternoon, when a strong low pressure over the Northern Great Plains will cause gusty northeasterly winds to funnel towards Duluth Harbor over 20 kt. The track, timing, and intensity of the low becomes uncertain after Monday night, but gales could occur (~20%) if the low tracks directly over Lake Superior with a moderate strength. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...TAP LONG TERM...GS AVIATION...07 MARINE...GS