Area Forecast Discussion
Issued by NWS State College, PA
Issued by NWS State College, PA
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983 FXUS61 KCTP 300533 AFDCTP Area Forecast Discussion National Weather Service State College PA 133 AM EDT Tue Apr 30 2024 .SYNOPSIS... Low amplitude upper level ridging is anticipated over the next week, with shortwave passages occurring Tuesday and next weekend. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... Satellite loop at 03Z shows building cumulus over the Alleghenies in region of falling heights/moistening boundary layer ahead of a weak mid level vort max lifting up the Appalachians. Most near term model guidance continues to support the chance of an isolated shower across primarily the north-central mountains as this feature lifts over the area late tonight. The vort max and any potential showers should have lifted north of the NY border before dawn. For most of the area, expect mostly clear skies overnight. However, a back door cold front pushing into Eastern PA and the associated upsloping southeast flow could yield late night stratus over portions of Schuylkill County. After today`s near record-breaking temps, decent radiational cooling associated with mostly clear skies and light wind should result in overnight min temps near 60F. && .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM WEDNESDAY/... The focus on Tuesday will be on a weakening upper level shortwave over the Midwest, which will push across the region Tuesday night. Modest height falls, combined with a plume of +2-3SD PWATs along the attendant low level jet, should support a round of showers and possible tsra across most of Central PA. focused during early afternoon over the NW Mtns, late afternoon over the central counties, and during the evening over the Lower Susq Valley. Tall, skinny cape in the 500-1000 J/kg range, combined with high pwats, support some locally heavy downpours. The 12Z HREF supports isolated amounts to around 1.5 inches over the northeast portion of the CWA. Given the low FFG values, can`t rule out minor flooding in a few spots. Relatively modest instability/shear profiles indicate the threat of any severe weather is low. Increasing cloud cover and showers should result in a cooler Tuesday for much of the area, especially over the NW Mtns where thick cloud cover will arrive early. Partly sunny skies, 850mb temps around 14C and a late day arrival of any showers should allow readings to reach the mid 80s over the Lower Susq Valley. Diminishing showers are expected from west to east Tuesday night, 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 /06Z TUESDAY THROUGH SATURDAY/... A few showers have developed across the northwest and could impact BFD overnight. Instability is limited over this area, so thunder is unlikely with this shower activity. Guidance does not show too much in the way of fog development into the morning, but it is certainly possible that MVFR visibilities could impact locations that see any rain. Weak troughing over the central mtns in the morning, and a cold front will be approaching from the west. However, the front will take much of the day to cross the Central PA. The moisture feed is not great, but modest instability will support at least a few thunderstorms during the afternoon and evening across the region. After the front passes, there will be lower clouds hanging out for many hours post-frontal passage, and these will linger into the night over the western mtns (JST/BFD). These should diminish on Wed AM. Could see some fog develop overnight and into Wednesday morning, especially in any locations that see some breaks in the clouds behind the front. 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...Lambert NEAR TERM...Fitzgerald SHORT TERM...Fitzgerald LONG TERM...Fitzgerald AVIATION...Dangelo/Bauco CLIMATE...Banghoff/Colbert