Area Forecast Discussion
Issued by NWS State College, PA
Issued by NWS State College, PA
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060 FXUS61 KCTP 120511 AFDCTP Area Forecast Discussion National Weather Service State College PA 111 AM EDT Wed Jun 12 2024 .SYNOPSIS... * High pressure will build over Pennsylvania through Wednesday. * As the high drifts east of the region, heat and humidity will ramp up for Thursday and Friday, followed by a cold frontal passage with scattered thunderstorms during the day Friday. * 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 THIS MORNING/... A stubborn deck of stratocumulus continues to ever so slowly erode from southwest to northeast this evening as high pressure continues to build into the region. These low clouds should clear out by midnight in northeast PA. Meanwhile, some high clouds associated with a weak front north of PA underneath a subtle shortwave will stream in by daybreak. The arrival of high pressure should support light and variable winds overnight. Biggest question for tonight`s forecast is the formation and extent of radiation fog. Dewpoint depressions in the northern tier are only 5-7F, which is easily attainable with a full night of radiational cooling. If clouds hang on a bit longer tonight, fog extent could be limited before the arrival of higher clouds. Have included the chance for patchy fog in deepest valleys in the northern mountains where confidence is highest. By daybreak Wednesday, low temperatures will range from the upper 40s northwest to mid 50s southeast. && .SHORT TERM /6 AM THIS MORNING THROUGH FRIDAY NIGHT/... Wednesday will be a transition day between much below normal temps to start the week and warmer weather for Thursday and Friday. Variable amounts of mid and high clouds on Wed will have only a minimal impact on the otherwise abundant sunshine with highs ranging from the low to mid 70s over the Northern Mtns to the low 80s throughout the Valleys of Central and southern PA. These readings will be just a few deg F shy of climo. Winds will be light from the west. PWAT values will start out around 0.8 inch and will increase to around 1 inch Wed afternoon, but it won`t feel humid given sfc dewpoints remaining in the 40s and 50s. We`re still expecting a warm up for the second half of the week, with many locations seeing their warmest temps on Thursday, except perhaps southeast PA seeing temps a few degrees warmer on Fri. Temperatures on Friday will depend on the timing of clouds and convection associated with an approaching cold front. Over the past 24 hours, models have generally sped up the arrival time and southward progression of the aforementioned front, now bringing a chance of showers and thunderstorms to the northern Alleghenies as early as Thursday night, and then dropping south across central PA during the day Fri with more numerous showers and thunderstorms. 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 will be noteworthy. && .LONG TERM /SATURDAY THROUGH TUESDAY/... Next weekend looks dry, as a northerly flow of drier air from Canada is advected into our area. Plenty of sunshine and fair weather is expected for Saturday and Sunday with a beautiful weekend in store. Any slight cool down on Saturday will be short- lived, with warmer temperatures progged to build back into the area Sunday into Monday. A few isolated sprinkles could be possible in the northern tier of PA with weak diurnally driven updrafts on Monday afternoon. By Tuesday, the risk for excessive heat will increase as a large ridge builds over the eastern US. There remains quite a bit of spread in model guidance, but potential exists for heat index values topping 100F in southeast PA Tuesday - Thursday next week. The ECENS is more bullish with the strength and northern extent of the ridge of high pressure into PA, which would result in higher temperatures and heat index values. The GEFS is a bit cooler with a weaker high and potential convection associated with a shortwave moving along the ridge, but still indicates the potential for excessive heat. Based on this anomalous pattern, the Climate Prediction Center has placed much of eastern PA in a Moderate Risk for Excessive Heat for the middle of next week (Wednesday - Friday). && .AVIATION /05Z WEDNESDAY THROUGH SUNDAY/... 06z update... Patchy fog has developed early this morning across the northern tier river valleys of the Commonwealth, as per satellite imagery and surface observations. Thus, we expect KBFD to see conditions as low as IFR through about daybreak. We have a high degree of confidence (90+%) that fog and low clouds will burn off quickly later this morning, generally by 12-13z. Otherwise, VFR will prevail, with a very dry air mass traversing the region over the next 24 hours or so. Surface winds look light, generally 5 kt or less. Outlook... Thu...Predominantly VFR w/ no sig wx expected. Fri...Restrictions possible in CB/TSRA. Sat-Sun...Predominantly VFR. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Banghoff NEAR TERM...Banghoff/Colbert SHORT TERM...Banghoff/Colbert LONG TERM...Banghoff/Evanego AVIATION...Jurewicz/Martin