####018005762#### FXUS61 KCTP 031645 AFDCTP Area Forecast Discussion National Weather Service State College PA 1245 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 increaing 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 extended period will trend milder and remain unsettled with several chances for rain. A cold front will stall near or south of the MD line Monday and Tuesday before lifting to the northeast (as a warm front) into midweek. The favors the best chance for rain the SW zones on Monday before POPs increase to 50-70% Tuesday into Wednesday. After a weekend cooldown, temps will trend warmer/back above climo into the 70s to low 80s. With several chances for rain next week along with persistent mild temperatures, green up should rapidly expand into northern PA thus ending the spring fire weather season. Additionally, there is no chance for frost or freeze conditions through the end of the week. && .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/... VFR/unrestricted conditions should remain in place across central PA terminal sites into this evening. Confidence on this scenario is fairly high (70-90%). An area of showers could reach the Allegheny Highlands late in the day (as early as 21-22z) and perhaps bring fuel alternate- MVFR restrictions at KJST and KBFD. The threat for MVFR cigs then increases substantially between 22z Fri and 02z Sat across the Laurels and Alleghenies, including JST, BFD, AOO, and UNV. Conds will continue to deteriorate Fri night into early Sat morning as southeast onshore flow advects cooler, moist air from the North Atlantic. IFR cigs are likely (60 percent chance or higher) for most TAF sites by 12z Sat, with the exception of IPT. Light surface winds will increase out of the SE to 5-10 kt Friday. Occasional gusts of around 20 kt could occur in the afternoon. Southeast flow will continue into Saturday. Outlook... Sat-Sun...Widespread restrictions due to low cigs. SHRA likely with a chance of TSRA. Mon-Tues...AM fog/clouds poss. PM -SHRA possible areawide. && .CLIMATE... Several records were tied or set on Thursday May 2nd: SITE OBSERVED TEMP PREVIOUS RECORD Altoona 87F 87 in 1954 Harrisburg 90F 88 in 1913 State College ??* 86 in 1938 Williamsport 89F 89 in 2018 *Official report from State College will be available Friday morning. May 2nd was also the first 90F day at Harrisburg. It is the 13th earliest 90F day on record. The earliest 90F day occurred on April 17th in 1896 and 2002. The average first 90F day is June 1st. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Steinbugl/Bowen NEAR TERM...Steinbugl/Bowen SHORT TERM...Steinbugl/Bowen LONG TERM...Steinbugl/Banghoff AVIATION...Jurewicz/Colbert CLIMATE...Steinbugl/Banghoff ####018007704#### FXUS66 KLOX 031649 AFDLOX Area Forecast Discussion National Weather Service Los Angeles/Oxnard CA 949 AM PDT Fri May 3 2024 .SYNOPSIS...03/909 AM. A cooling trend will begin today with a deepening marine layer through the weekend. A storm system will brush the area to the north this weekend with a chance for light precipitation later Saturday into Sunday. Night and morning low clouds and fog will struggle to clear at the coast today, then spread back inland tonight. A warming and drying trend will develop next week. && .SHORT TERM (TDY-SUN)...03/919 AM. ***UPDATE*** The marine layer has deepened to around 3500 feet across the LA Basin, sloping down to around 1000 feet along the Central Coast. The eddy is a little weaker than yesterday but onshore flow is stronger and it will take longer to clear the stratus today and through the weekend. Still looks like a high chance of rain along the Central Coast Saturday afternoon (around a quarter inch) as a late season storm moves into northern California, but mostly just brushes by our area. Farther south, rain chances will be Saturday night into early Sunday and lighter, mostly under a tenth of an inch. And like this morning some areas will see morning drizzle both Saturday and Sunday. With the storm exiting to the east Sunday and the flow shifting to the west/northwest there should be much better clearing in most areas. ***From Previous Discussion*** The storm system, over the Gulf of Alaska this morning, will dig south into northern California through Saturday night, brushing the area to the north. A cold frontal boundary will drop south into the region on Saturday, bringing rain to much of the area. PoPs have been nudged higher in the latest forecast, going higher than NBM solutions. All of the ensemble members have light precipitation developing for areas north of Point Conception, along the northern slopes of the mountains, and across eastern Los Angeles County. The forecast is little more questionable for southern Santa Barbara County, Ventura County, and western Los Angeles County. The forecast trends wetter as deterministic solutions are starting to trend more southwest to west with the low-level flow pattern. The forecast trends more toward the deterministic solutions south of Point Conception, buying into the model trends. Model tabular forecast output suggests a high- to- likely chance of rain for areas north of Point Conception, and moderate-to-high chance for areas southwest of Point Conception. There is a moderate chance that southern Santa Barbara County, Ventura County, and western Los Angeles County could end up being in a rain shadow effect as downsloping occurs from the Transverse Ranges. Rainfall amounts will likely range from a quarter inch or less, except a quarter to half inch across northwestern San Luis Obispo County. Amounts will be highest for the northern portion of the area and along the northern slopes of the mountains. Rainfall will only amount to a few hundredths at most for most coastal and valley areas south of Point Conception. Gusty west to northwest winds will develop across many coastal areas, into the Santa Ynez Valley, across southern Santa Barbara, up into the Interstate 5 Corridor, and down into the Antelope Valley. EPS solutions indicate good agreement across the area for the potential for wind advisory, but a handful of solutions indicate a gust potential over 55 mph at KSDB. This will need to be monitored as we get closer as wind gusts have been trending generally higher with each run. A colder air mass will spread into the area between Saturday and Sunday night with the cold front. Temperatures during this stretch trend colder than NBM values, and Sunday could be a cold day for May, similar to a February or March with 60s being common across the coastal and valley areas. .LONG TERM (MON-THU)...03/415 AM. A warming and drying trend will develop for the work week next week as high pressure aloft reestablishes. The forecast ensembles agree with a warming trend extending through at least Thursday. EPS solutions tend to hold onto the warming trend extending into next weekend. EPS cloud cover means point to the marine layer depth being kept in check, but confidence is moderate at best in this solution as we are in May. The latest forecast keeps some marine layer induced low clouds and clouds returning to coastal areas by mid week. && .AVIATION...03/1649Z. At 1600Z at KLAX, the marine layer was 3300 feet deep. The top of the inversion was at 4300 feet with a temperature of 13 degrees Celsius. Overall, moderate to high confidence in 18Z TAF. There is a 40% chance that MVFR CIGs could remain at KSBA and KLAX through the afternoon. For tonight, high confidence in return of CIG/VSBY restrictions for all coastal and valley sites, but moderate confidence in timing of return and flight category changes. KLAX...Moderate confidence in 18Z TAF. There is a 40% chance that MVFR CIGs will not dissipate this afternoon. No significant easterly wind component is expected. KBUR...Moderate confidence in 18Z TAF. THere is a 20-30% chance that MVFR CIGs do not dissipate this afternoon. For tonight, there is a 30% chance that MVFR CIGs could arrive as early as 03Z. && .MARINE...03/723 AM. For the Outer Waters, Small Craft Advisory (SCA) level winds are expected to increase to Gales (70% chance) this afternoon, with the strongest winds off the coast. Gales will continue thru late tonight, then drop to SCA levels. Winds may even drop below SCA level for a while Sat morning, but seas will remain above SCA levels. SCA level winds are expected (80% chance) Sat afternoon, then continue much of the time thru Tue. There is a 50% chance of Gale force winds Sun afternoon/evening, then a 30-40% chance during the afternoon/eve hours Mon thru Tue. For the Inner Waters north of Point Sal, SCA level winds will develop today, then continue thru late tonight. There is a 40-50% chance of SCA level winds/seas during the afternoon/eve hours Sat, then SCA winds are likely (70% chance) during the afternoon/eve hours Sun thru Tue. There is a 30% chance of gales Sun afternoon/eve. For the Santa Barbara Channel, there is a 40% chance of SCA level winds in western portions of the channel this afternoon thru late tonight, then Sat afternoon/eve. SCA level W-NW winds are expected Sat night thru late Sun night (80% chance), and are likely (60-70% chance) during the late afternoon thru late night hours Mon thru Tue. There is a 30% chance of gales Sun afternoon/eve. For the Southern Inner Waters, there is a 30% chance of SCA level winds from Anacapa Island to Malibu during the late afternoon/eve hours Sat. SCA level winds are likely (70% chance) Sat night thru late Sun night. There is a 40% chance of SCA level winds during the late afternoon thru late evening hours Mon thru Tue. && .LOX WATCHES/WARNINGS/ADVISORIES... CA...NONE. PZ...Small Craft Advisory in effect until 3 AM PDT Saturday for zone 645. (See LAXMWWLOX). Gale Warning in effect until 3 AM PDT Saturday for zones 670-673-676. (See LAXMWWLOX). && $$ PUBLIC...MW/Hall AVIATION...RAT MARINE...DB/RAT SYNOPSIS...MW/Hall weather.gov/losangeles Experimental Graphical Hazardous Weather Outlook at: https://www.weather.gov/erh/ghwo?wfo=lox