Area Forecast Discussion
Issued by NWS State College, PA

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850 FXUS61 KCTP 231140 AFDCTP Area Forecast Discussion National Weather Service State College PA 740 AM EDT SAT JUL 23 2016 .SYNOPSIS... 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 generally dry. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Mainly clear skies and rather muggy conditions continue across the region with a generally light westerly breeze, temps in the l-m 70s, and dewpoints in the 60s. A few, dissipating brief showers will drift southeast across the endless mtns region of NEPA over the next hour or so. lows around sunrise will average around 10 deg above normal for Late July. A relatively weak, sfc cold front extending across Lake Ontario and Lake Erie at 0730Z will drift SE to near the NY/PA border by 12-14Z...then sag slowly south of Interstate 80 early this afternoon...before nearing the Mason/Dixon line this evening. The timing of this front and notably drier air/lower PWATs behind it suggest very little or no threat for SHRA across northern PA...while even locations along and south of it in the 18z Sat-00Z Sun period will find it very difficult to pop up shows through the warm mid-level temps (+8-9C at 700 mb) and deep dry air aloft. The moderately gusty West to WNW flow (in the teens to around 20 kts during the midday and afternoon hours) just in advance and behind the cfront this afternoon will allow temps to rise to hot levels once again. Mid to late afternoon high temps today will range from the mid to upper 80s across the highest terrain of the north and west...to the mid and upper 90s in the Lower Susquehanna Valley. Certainly and unfortunately, no relief for agricultural interests badly in need of rain. The high dewpoints in the upper 60s 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. && .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 /12Z SATURDAY THROUGH WEDNESDAY/...
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Clouds are banking up against the Laurels this morning. This has brought MVFR to even very briefly IFR conditions. The cigs/bases are higher elsewhere. But, the residual moisture could linger for another few hours. Expect VFR for the rest of the period. The wind will pick up to a decent breeze this afternoon as we mix up to fl050. There is the smallest chance for a shower or tsra 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 - fog forming in just a few locations and light wind. Sunday also looks hot and dusty. Winds should be lighter with sfc ridge axis right 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...Lambert NEAR TERM...Lambert SHORT TERM...Lambert LONG TERM...Lambert/RXR AVIATION...Dangelo

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