Area Forecast Discussion
Issued by NWS State College, PA
Issued by NWS State College, PA
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342 FXUS61 KCTP 301459 AFDCTP Area Forecast Discussion National Weather Service State College PA 1059 AM EDT Tue Apr 30 2024 .SYNOPSIS... -Summerlike to close out April with showers and a few t-storms -Dry weather with lower humidity Wednesday through Thursday -Trending unsettled into the weekend with rain likely Sat/Sun && .NEAR TERM /UNTIL 8 PM THIS EVENING/... 1050AM/1450UTC: Minor adjustments to hourly temps and POPs based on the latest radar and satellite trends. Added a few degrees to max temps and added +RW to wx grid in the MRGL risk ERO area which has been scaled back to only include the northeastern counties adjacent to BGM/PHI. Latest hires guidance keeps heaviest rain closer to the Catskills and in the Poconos this afternoon with quick moving storms maintaining low flood risk. Previous Discussion Issued: 454 AM EDT Tue Apr 30 2024 Low level theta-E ridge axis and moderate amount of llvl moisture convergence along its western edge and near a sfc quasi-stnry boundary that`s sagged into Ncent PA will bring the chance for a few isolated SHRA/TSRA near and to the north of the KIPT area through the mid morning. A cold front moving through Ohio this morning will reach the Western Mtns of PA late this afternoon. Target periods for the best chance of showers (and isolated TSRA) will be between 11 Am and 4 Pm across the Northwest Mountains, during the mid afternoon to early evening over the Laurel Highlands, Central Mountains and the Susquehanna`s West Branch Valley, and during the late afternoon through the evening over the Middle and Lower Susquehanna Valley. Fairly thin CAPE today with Equil Levels between about 26-28 KFT AGL will support some isolated to scattered embedded TSRA capable of producing a quick one half inch of rainfall, small hail and brief gusty winds of 40 to 50 mph. Severe threat appears low with any decent amount of shear confined to the lowest 0.5 KM agl and unidirectional flow with very little speed shear aloft. Best chance (albeit only around 50 percent) to exceed 1000 J/KG of SFC based CAPE per the 30/03z SREF will be across Lancaster County early this evening, while the greatest LLVL directional and speed shear will be found to the north of the KIPT area in the vicinity of a 1010mb sfc low forming along a lee trough with PWAT values between 1-1.25 inches. With their latest update, WPC trimmed their MRGL risk area for Excessive Rain to cover just the northern half of PA today/this evening. Forecast QPF today into early tonight varies from around 1.00 inch across Sullivan County in our NE and perhaps less than 0.10 throughout some of our South-Central Valleys Morning showers and mid to late afternoon passage of the aforementioned cold front will yield the coolest high temps today acrs the NW Mtns, where temps could be capped off in the upper 60s. In Contrast, the Middle and Lower Susq Valley will heat up nicely into the low and mid 80s, under just some cirrus for the bulk of the day with showers generally after 19 or 20Z. && .SHORT TERM /8 PM THIS EVENING THROUGH 6 PM WEDNESDAY/... Diminishing showers are expected from west to east tonight, as the shortwave traverses the state. Latest guidance points to fair weather for most if not all of the forecast area Wednesday, as surface ridging and much drier air work into the state behind the exiting shortwave. Mixing down forecast 850mb temps of around 11C yields expected highs in the 70s Wednesday. We have leaned toward the lower NBM10pct dewpoints Wed afternoon based on dry air above a weak inversion in the model soundings. && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... Upper level ridging building over the region should ensure fair and warm conditions Wed night through at least early Friday. High pressure tracking north of PA into the Canadian Maritimes will then result in a developing easterly flow and the onset of cooler conditions Friday PM into next weekend. All medium range guidance points to a rainy and cool weekend, especially the first half, as a southerly low level jet linked to an upper trough over the Grt Lks and an associated plume of deep moisture overruns a stationary front over the Ohio Valley. Latest EPS plumes indicate around a half inch of rain is likely by late Sunday. Passage of the upper trough and associated occluded front appears likely to bring drier and warmer conditions by Monday of next week. && .AVIATION /15Z TUESDAY THROUGH SATURDAY/... VFR conditions will continue for at least the next few hours. A cold front approaching from the west will slowly track through Central PA through the day and will bring showers and thunderstorms to the region. As the showers and storms move in, ceilings will gradually lower to MVFR and brief visibility restrictions will be possible in any heavier thunderstorms. After the front passes, low clouds will linger into the overnight hours, especially over the western mtns (JST/BFD). These should diminish in the early morning on Wednesday. We could see some fog develop overnight and into Wednesday morning, especially in any locations that see some breaks in the clouds behind the front. Currently, the HREF and SREF show a 30-50% chance of IFR visibilities developing after 06Z across the western mountains. Outlook... Wed...Early AM low cigs possible W Mtns. Thu...No sig wx expected. Fri...Evening showers/cig reductions possible. Sat...Widespread SHRA/TSRA. IFR poss. && .CLIMATE... Record high temperatures were set at the following locations today (Monday): SITE 2024 OBS PRVS RECORD Altoona 86F 83F (1956) Bradford 82F 76F (1984) Williamsport 89F 86F (1942/1974) && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Steinbugl NEAR TERM...Lambert/Fitzgerald/Steinbugl SHORT TERM...Lambert/Fitzgerald LONG TERM...Fitzgerald AVIATION...Dangelo/Bauco CLIMATE...Banghoff/Colbert