Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 310249 AFDCTP Area Forecast Discussion National Weather Service State College PA 1049 PM EDT SAT JUL 30 2016 .SYNOPSIS... A plume of deep moisture on the west side of the subtropical ridge will produce showers and thunderstorms over the region into early Sunday. A weak trough will push the deep moisture to our east Sunday. Behind this system it will slowly dry out. A ridge building to our west early next week will work its way eastward producing some hot weather later in the week. This surge of warm air appears to be just ahead of what could be a real cold front and a real break from the warm weather we have had for the past month. && .NEAR TERM /UNTIL 8 AM SUNDAY MORNING/... a broken line of weakening showers and isolated storms is propogating south of the Laurel Highlands late this evening. the northern portion of this line will brush the Laurels over the next few hours. Scattered showers with isolated thunder will lift to the upper Susquehanna through midnight. Expect only isolated additional shra/tsra overnight...with the exception of the northwest where greater coverage should break out in the pre dawn hours as another shortwave lifts towards the GLAKS from the Ohio Valley. Current cells over far northwest Pa are backbuilding...and that could be the case overnight as well. Areas of fog should be widespread overnight...with many areas seeing vsbys below one mile thanks to plentiful residual llvl moisture from afternoon/evening rainfall. && .SHORT TERM /8 AM SUNDAY MORNING THROUGH 6 PM SUNDAY/... Sunday will feature more of the same...with a bit less coverage the diminished deep layer moisture as the 2" PW plume will have been displaced off of the eastern seaboard. This will allow temps to warm several degrees higher than today`s...which will spark another round of afternoon and evening shra and tsra. && .LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/... Short-waves sweeps to the coast but broad upper level trough lingering across PA. The main trough axis lies through Central PA by 12z Monday and slowly progresses east through the day. With the trough and cyclonic flow aloft scattered showers/isolated thunderstorms are possible with best chances over the eastern counties in the afternoon. High pressure builds in Monday night and everything begins drying out. For Tuesday into Wednesday a sharp upper level ridge is to our west over the Great Lake region with the trough now off the coast, dry NW flow and surface high pressure across the region. Short-wave weakens the ridge into Thursday. ECMWF takes this south across Ohio into VA leaving PA dry. GFS is weaker and further north with some convection over the PA mountains which it moves east across PA through Thursday night. Stayed closer to the ECMWF solution with no POPs at this point. Both models agree on a more rigorous cold front dropping southeast toward PA on Friday. This will help surge the temperatures and humidity up ahead of it over central PA Friday. Right now the timing is such that late day convective storms will feed off the days heat and humidity and roll through late in the day into the overnight. Models bring the cold front southeast across PA overnight and then stall it near the Mason-Dixon Line for Saturday. && .AVIATION /03Z SUNDAY THROUGH THURSDAY/...
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Rain tapering off to sct showers late this evening as upper lvl disturbance shifts east of the area. Partial clearing, combined with wet ground and light wind, will promote areas of fog/low cigs overnight. Blend of latest mdl guidance supports the idea of fairly widespread IFR/LIFR conds overnight with onset btwn 02Z-06Z based on latest LAMP guidance and NCAR ensemble. Mdl soundings indicate fog/low cigs will lift by late am, with widespread VFR likely by aftn. Sct shra/tsra are likely form during the aftn, which could produce a brief vis reduction in spots thru early evening. OUTLOOK... MON...Am fog possible, then isold pm tsra impacts possible. TUE...Am fog possible. WED...No sig wx expected. THU...Isold pm tsra impacts possible western Pa.
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&& .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Grumm NEAR TERM...Grumm/DeVoir SHORT TERM...Grumm LONG TERM...Watson AVIATION...Fitzgerald

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