Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 231516 AFDCTP Area Forecast Discussion National Weather Service State College PA 1116 AM EDT SAT JUL 23 2016 .SYNOPSIS...
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Pennsylvania will be on the northern edge of the subtropical ridge into next week. A series of weakening cold fronts will bring the mention of mainly afternoon or evening showers or thunderstorms in the forecast, but most of the time it will be fair, very warm and humid but rain free.
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&& .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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Weak moisture convergence has resulted in patches of low clouds over the SW portion of my forecast area. Otherwise it hazy warm and humid and will continue as such for the remainder of the day. A weak cold front entering NW Pa early today will sag slowly south of Interstate 80 early this afternoon...before nearing the Mason/Dixon line this evening. It is still quite warm and dry aloft and the lack of significant forcing keeps confidence high that rain will be hard to come by today despite the rather sultry dewpoints in places over much of the region. At this point the best chance of rain, a very low chance at that, looks like it will be over the very southern tier later today as mid level temps are forecast to decrease slightly as the front provides a small enhancement in the low level convergence. The downslope flow associated with a gusty West to WNW wind (in the teens to around 20 mph during the midday and afternoon hours) just in advance and behind the front combined with 850 temps right around 20C should easily support max temps ranging from the mid 80s to mid 90s NW to SE. With no widespread rain in the cards, no relief for agricultural interests is seen. The high dewpoints in the upper 60s to mid 70s across the Southern Valleys will lead to Heat Indices in the upper 90s (just shy of Heat Advisory criteria), while the decreasing dewpoints behind the front will limit Heat Indices to below 90F across the Northern Mountains.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/... A ridge of high pressure extending south into the state tonight and Sunday will bring mainly clear skies and slightly cooler temps tonight, with lows early Sunday near 60F across the north and 65-70F over the southern half of the state. Sunday should feature abundant Sunshine for most or all of the day...along with very warm to hot temps. 850 mb temps will actually rebound by 2-3C on Sunday...compared with those on Saturday. Highs on Sunday will be very similar to Saturday`s. && .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... Big story in the extended fcst is the expected heat wave lasting into early in the upcoming week, as the axis of the subtropical ridge briefly shifts from the plains to the northeast conus. Anomalous upper lvl ridging building over PA should bring hot and mainly dry wx this weekend, as warm temps aloft suppress convection. Next chance of shra/tsra for most of the area comes Monday ahead of shortwave working across the Great Lakes. However, any rainfall Monday is likely to do little to stem the dry pattern we have been in. Latest GEFS mean qpf is up to a half an inch at most. 12Z ECENS/NAEFS mean 8h temps are near 22C Saturday through Monday, indicating the potential of several days in a row with highs in the 90s in the valleys. The hottest temps look to be on Saturday as latest GEFS gives high temperature anomalies in the +4 standard deviation and have slightly backed off on Sunday. Have adjusted Max temperatures accordingly. Heat indices around 100F appear possible by Mon across the Susq Valley, as higher dewpoints are advected into the area ahead of potential convection. Overnight lows are also a concern as the area doesn`t cool off at night through the weekend with Southern PA lows in the 70s with highest readings Monday morning. Some modest cooling appears likely by Tue/Wed of next week behind weak cold front. However, temps still likely to remain somewhat abv normal within a generally zonal flow. Midweek weather looks dry again, with just low pops for isolated tstms. Fri looks to be the next higher chance for tstm impacts areawide as another cool front progged to move through. && .AVIATION /15Z SATURDAY THROUGH WEDNESDAY/...
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Just a couple of pockets of MVFR ceilings left from the early morning clouds that banked up against the Laurels. Expect widespread VFR for the rest of the day into the overnight. A gusty west to WNW wind will develop by afternoon, in the range of 10-20kt. There is a very small chance for a shower or thunderstorm to pop up into KJST or KLNS this aftn/evening. Will not mention in the TAFs quite yet. High pressure, subsidence and warm temps aloft will do their best to quell the instability. Expect more of the same tonight with fog forming in just a few locations in and around sunrise, with light wind. Sunday also looks hot and dusty. Winds should be lighter with the surface ridge overhead. OUTLOOK... MON...Scattered restrictions possible with a cold front bringing scattered showers and thunderstorms. TUE-WED...No sig wx.
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&& .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...La Corte/Lambert NEAR TERM...La Corte/Lambert SHORT TERM...Lambert LONG TERM...Lambert/RXR AVIATION...Dangelo/La Corte

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