####018006591#### FXUS61 KCTP 031813 AFDCTP Area Forecast Discussion National Weather Service State College PA 213 PM EDT Fri May 3 2024 .SYNOPSIS... -Scattered showers and thunderstorms will begin this afternoon mainly in western PA as clouds increase -Noticeable cool down over the weekend with overcast skies and periods of rain -Remaining unsettled next week with a gradual warming trend && .NEAR TERM /THROUGH TONIGHT/... The early afternoon hours will remain partly cloudy before increasing cloud cover into the early evening. High pressure channeling down the eastern slopes of the Appalachians will maintain dry wx over the majority of the CWA (eastern 2/3) through 00Z Sat with max POPs to the west of the US219 corridor. This area should be in the warm sector where the most unstable air will reside. A couple of locally heavy t-storm downpours could produce spot amounts >1" on the west aspect of the Allegheny Plateau near the edge of higher pwat air surging in from the upper OH Valley. The WPC D1 ERO covers this area, with the greatest threat just outside of our CWA (over PBZ) based on the latest 03/12Z HREF guidance. The 24hr maxTchange will be considerably cooler over the central and southeastern ridge/valley region this afternoon with fcst highs giving back 7-15 degrees from yesterdays record challenging to record breaking temps. Shower activity should eventually expand west to east through tonight with a surface boundary stalling out over far western PA. An increasingly moist east/southeast flow brings widespread low clouds and perhaps some fog/mist on the ridgetops. The potential for not severe t-storms remains low given the lack of instability and the increasing low level stable air with the CAD setup. Low temps will be above early May climo and range between 45-55F from the southwestern Poconos/Coal Region to Warren County. && .SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... Hires models show CAD pattern firmly entrenched over CPA on Saturday, and therefore we continued to trim max temps vs. NBM. The current thinking is most areas will remain in the mid to low 50s given the easterly flow. No risk of thunder on Saturday so removed from wx grids and changed character of precip to rain from showers. No major changes to the Sunday fcst were made other than increasing rain PoPs through early Sunday morning. Rain/showers continue through Sunday and into Sunday night with highs recovering 5-10F over the southwest 1/2 of the CWA. Some isolated convection is possible in this area Sunday PM as the warm sector shifts to the east. Despite the relatively high moisture availability, limited rain rates should keep blended mean QPF btwn 0.50-1.00 inches ending 00Z Monday. Fcst lows Sunday night will be +10-15F above climo for early May in the 50-60F range. && .LONG TERM /MONDAY THROUGH THURSDAY/... The long term period will be dominated by WSW flow aloft. Sfc boundaries linger overhead/nearby the state for the entire period. Several successive shots of shortwaves should slide overhead, likely the remnants of a very active/stormy time over the central plains. Thankfully, the expected severe weather in the middle of the country is not expected to extend this far to the east on most (if any of the) days. However, we do get the forcing provided by the repeated MCSs. These things are highly difficult to track and anticipate the timing of arrival, too, 4-7 days out. The ECMWF does push the boundary south of PA enough for Tues to be dry. But...the GFS and importantly, the blend of models, never let go of 30-80 PoPs. Gulf moisture really never gets totally cut off from reaching the OH Valley/Mid-Atlantic States, but does diminish somewhere in the vicinity of PA. Thus, there is high confidence of a wet period during the entire long term, esp for srn PA, but extremely low confidence in timing of each successive wave. PoPs >30pct will remain for each 12hr period, as there is no model or conceptual consensus to dip that low. They also won't go above 80 pct for much the same reason. && .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/... Heating popping a few taller cu from N of IPT to UNV to JST. So, much of the area should be VFR for the next 6-12 hrs. None of these have more than the faintest of returns on radar at 18Z. A strong shortwave/area of positive forcing is approaching from the west and is carrying a broach patch of SHRA but no TS just yet. Outflow boundary moving toward BFD from the NW and earlier convection has dropped the temps and turned the wind to the N/NW over NErn PA (ERI/GKJ) already. Only small cu are seen along the boundary as it moves southeastward early this aftn. The heating of the day should provide just enough kick to help storms occur in wrn PA (perhaps even into JST and BFD before 21Z). The stability in the lowest 5kft overhead should keep storms from moving too deep/far eastward into the central mtns (UNV/AOO). We have fairly high confidence in a no TS fcst for IPT/MDT/LNS at this point. Still, the SHRA do progress eastward all night, and may make it into those terminals by 12Z. Have only mentioned VCTS for BFD and JST at this point with low (30pct) confidence that they will have a TSRA for long enough to justify a categorical period with TS occurring as the prevailing wx type. Low clouds and some fog will develop in many places overnight due to increasingly humid air and a near-constant SErly llvl wind. LIFR looks probable (80%) at JST and IFR probably (80%) at BFD, AOO, UNV beginning in the middle to latter period of the night. Will hold off on mentioning any IFR cigs/vsby at the eastern terminals for now. Sat looks unsettled, too. Widespread light SHRA are expected for the srn terminals for all of Sat, and the IFR may linger for the SWrn terminals and may creep into MDT/LNS, too. BFD may actually be the best location for flying into/out from on Sat when compared to the other central PA terminals. Outlook... Sun...Widespread restrictions due to low cigs. SHRA likely with a chance of TSRA. Mon-Wed...AM fog/clouds poss. PM -SHRA possible areawide. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Steinbugl/Bowen NEAR TERM...Steinbugl/Bowen SHORT TERM...Steinbugl/Bowen LONG TERM...Dangelo AVIATION...Dangelo ####018007219#### FXUS65 KBOU 031814 AFDBOU Area Forecast Discussion National Weather Service Denver/Boulder CO 1214 PM MDT Fri May 3 2024 .KEY MESSAGES... - Isolated showers on the northeast plains tonight. - Warmer and windy on Sunday. - Sunday night into Monday will see a good chance of snow showers in the mountains. Windy and cooler over the entire area. && .UPDATE... Issued at 1041 AM MDT Fri May 3 2024 Fairly quite morning weather-wise with temperatures rising into the 60s across the plains. It is plenty breezy across most of northeast Colorado with gusts 20-30 mph with locally higher gusts in the mountains. With plenty of sunshine and a shortwave trough passing to the north, instability continues to build across the region. Satellite shows cumulus development across the mountains with a few shower echos already forming in the northern mountains. The plains remain more stable this morning, but will become more unstable through the afternoon. This keeps the forecast on track for the scattered shower/storm threat mainly for the higher terrain and far east plains. A few strong to severe storms are possible on the far east plains with gusts up to 60 mph and up to quarter size hail. Made minor changes to the precipitation probabilities to better reflect timing of shower/storm chances for the northeast corner. && .SHORT TERM /Through tonight/... Issued at 336 AM MDT Fri May 3 2024 GOES-18 Mid-level Water Vapor displays showers and storms located in Wyoming this morning. The shortwave trough axis will likely stay to the north but our area should receive an increase in mid-level starting late morning. Additionally, a breezy day will occur through this evening across the region with wind gusts up to 35 mph as the shortwave trough lifts north. 700mb temperatures reach 6-8C; this will allow for afternoon temperatures to reach the upper 60s to lower 70s across the urban corridor and plains. Mountains and valleys should warm up to the mid 40s to 50s this afternoon. Weak instability between 100-300 J/kg will likely support scattered showers and storms this afternoon. Favorable conditions for severe storms are mainly along the Kansas Colorado border late afternoon and early evening. If a storm is able to develop in that environment, expect 1 inch hail and wind gusts up to 60 mph. With snow level roughly near 8k ft, higher elevations especially along the Park Range could accumulate snow up to 1-4 inches through Saturday morning. Late afternoon, a cold front will sweep into the CWA increasing wind gusts once more. This may produce wind gusts up to 45-50 mph. As the cold front passes, it is possible the environment becomes too stable to support any additional thunderstorm development. Tonight, drier air enters our region. Low temperatures remain near normal. && .LONG TERM /Saturday through Thursday/... Issued at 336 AM MDT Fri May 3 2024 The flow aloft will become WSW on Sat as a weak sfc lee trough develops by aftn. This will allow for SSE low level flow to develop across the plains. Some moisture will affect the higher terrain by aftn with MLCAPE around 200 j/kg. As a result, there will be a chc of aftn showers and a few tstms, especially over the higher terrain along and south of I-70. Across the plains it will be dry and cooler with highs in the 60's. By Sun, SW flow aloft will increase across the area as a storm system moves into the Great Basin. In addition, sfc low pres will intensify from central WY into ern CO with stg southerly flow in the lower levels. As a result, will likely see winds gusts in the 45-55 mph range across the plains Sun aftn. As far as precip chances, MLCAPE will rise to around 300 j/kg over portions of the plains, however, there is a capping inversion which probably will inhibit tstm development. Meanwhile, highs will be warmer over most of the plains as readings rise into the 70's. The only exception would be over the far ern plains, where highs may stay in the mid to upper 60s due to low level cloud cover. For Sun night into Mon, the storm system over the Great Basin will move quickly ENE with an intense upper level low moving into ern WY, by Mon aftn. As the srn extent of the upper level trough moves across nrn CO, there will be a round of snow in the mtns Sun night into Mon morning. Across the plains, a bora type front will move across during the day with gusty WNW winds developing by midday. There also could be a chc of showers in the morning as a quick shot of mid level ascent moves across. Highs across the plains will drop back into the 60's. Looking ahead to Mon night into Tue, an intense storm system will be over the nrn Plains. This will allow for brisk WNW flow aloft across the area. Cross-sections, show enough moisture embedded in the flow to bring a chc of orographic snow showers to the mtns. Across the plains, it will be dry with gusty WNW winds continuing. On Wed, the storm system will move slowly eastward with WNW flow aloft remaining over the region. Once again, there will be some moisture embedded in the flow to bring a chc of snow showers to the mtns. Across the plains, it will remain dry and windy with highs remaining in the 60's. By Thu, the flow aloft will become more NW as a shot of cooler air moves into the area behind a front. In addition, there may be a disturbance embedded in the flow which could bring a chc of precip to the region as well. && .AVIATION /18Z TAFS through 18Z Saturday/... Issued at 1155 AM MDT Fri May 3 2024 VFR conditions expected for the TAF period. Breezy S/SSE winds being observed at the terminals early this afternoon. This puts a slight delay on the forecasted SW winds. Within the next 1-2 hours winds should turn more SW ahead of the incoming front. Front will likely across the terminals in the 21-23z timeframe with a brief push of gusty N/NNE winds behind in (Gust 25-35kts). Winds turn more NE after 00z with weaker gusts than the initial push (G20-25 kts). Showers and storms develop on the plains around the front timeframe. Although they should remain clear of the terminals, can't rule out the potential for outflows/variable gusts from showers set up to the north and east. Ovenright, winds decrease becoming light ENE/NE. Saturday morning winds turn SE increasing to 8-10 kts by late morning. && .FIRE WEATHER... Issued at 256 AM MDT Fri May 3 2024 It will be windy over the plains Sunday through Tuesday. Humidity levels will gradually drop from Monday into Tuesday. However, recent rainfall combined with greening up of vegetation could reduce fire danger across portions of the plains. At the time, the most likely area for increasing fire danger would be over southern Lincoln county. && .BOU WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...Mensch SHORT TERM...AD LONG TERM...RPK AVIATION...Mensch FIRE WEATHER...RPK