Area Forecast Discussion
Issued by NWS State College, PA
Issued by NWS State College, PA
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225 FXUS61 KCTP 122306 AFDCTP Area Forecast Discussion National Weather Service State College PA 706 PM EDT Wed Jun 12 2024 .SYNOPSIS... High pressure will be centered over the Commonwealth today, supplying abundant sunshine and warmer temperatures, followed by a further increase in heat for Thursday and Friday as the high drifts off the Mid Atlantic Coast. A cold frontal passage on Friday will spark a round or two of showers and scattered thunderstorms, some of which could produce gusty winds, frequent lightning and hail. After a dry and warm weekend, a ridge of high pressure will bring an increased risk of excessive heat early next week with highs in the 80s and 90s and heat index values possibly exceeding 100F. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... Today will be dry and pleasant. Abundant sunshine will be accompanied by a few bands of cirrus and altocu along with afternoon fair weather cu. Highs will be in the mid to upper 70s across the higher terrain and low 80s in the Lower Susq Valley. These readings will be within a few degrees of climo. Sfc dewpoints in the mid 40s to low 50s will lead to min RH values of 30 to 45 percent this afternoon. Tonight will be tranquil and comfortably cool with min temps near 50F in the perennial cold spots across the Northern Mtns and Laurel Highlands and mid to upper 50s elsewhere. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH SATURDAY NIGHT/... Many locations will see their warmest temps on Thursday, except for perhaps portions of southeast PA, where temps could be a few degrees warmer on Fri. Highs are expected to range from the low 80s in the northern tier to near 90 across the southern valleys. The approaching cold front will bring a chance of showers and thunderstorms to the northern Alleghenies as early as Thursday night, and then drop south across central PA during the day Fri with more numerous showers and thunderstorms. There is still uncertainty with the timing of this precip and associated clouds, which will influence how high temps can rise across south central PA. Latest hires guidance has precip holding off until at least late afternoon in the southeast, allowing temps to first rise into the upper 80s to low 90s. Most places will see rainfall totals between 0.20 and 0.50 inch on Fri, with locally higher amounts possible in heavier downpours. SPC`s Day 3 outlook paints a MRGL risk for SVR TSRA across much of Central PA, while a SLGT Risk covers a small portion of our Eastern zones (the Western Poconos, south through the greater Harrisburg, Lebanon and Lancaster areas). Despite forecast high temps near 90 across southern zones Thu- Fri, relatively low levels of humidity (dewpoints 55-65F) will hold the heat index to just a couple deg above the air temp. Thus not anticipating heat products at this time. However, the +15-20 degree swing from temps well below normal early this week to the warm weather late this week is noteworthy. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... Dry conditions are expected to prevail through Tuesday afternoon outside of some isolated diurnally driven showers across the northern tier Monday afternoon and across much of north and western PA Tuesday afternoon. An extended period of above average temperatures is increasingly likely as a large ridge builds across the eastern US. This will allow for MaxTs and MinTs +10-15F above climatology for the middle of June. There remains some model difference with respect to the strength of the ridge, but generally better agreement of abnormally warm temperatures extending northward into PA. Less humid conditions on Monday will bring heat index values into the upper 90s, with some locations across southern PA pushing close to the 100F mark. Humidity during the afternoon hours will increase the risk for excessive heat on Tuesday with some potential for heat index values in the 100-105F across the Lower Susquehanna Valley. Humid conditions will continue into Wednesday with heat index values slightly lower than Tuesday, but still anomalously warm even for this time of the year. The Climate Prediction Center has placed much of eastern PA in a Moderate Risk for Excessive Heat for the middle and end of next week, outlining the longevity of heat across the region. && .AVIATION /23Z WEDNESDAY THROUGH MONDAY/... Not really any change for the 00Z package. Abnormally dry airmass in place has resulted in a layer of high base CU today. Not expecting fog or low clouds tonight, given the dry airmass in place. Winds remain rather light on Thursday, for the first warm day in a while. A chance of showers and storms on Friday with a cold front. Timing of the system and the lack of real high dewpoints may limit the coverage and intensity of the showers and storms. Activity quickly clears out late Friday. A dry weekend shaping up with VFR conditions. Perhaps a shower or storm late Monday, as a warmer airmass is advected eastward toward PA. Outlook... Fri...Restrictions possible in CB/TSRA. Sat-Sun...Predominantly VFR. Mon...Mainly VFR, chance of convection mainly northwest. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Lambert/Colbert NEAR TERM...Lambert/Colbert SHORT TERM...Lambert/Colbert LONG TERM...Banghoff/NPB AVIATION...Martin