Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 310014 AFDCTP Area Forecast Discussion National Weather Service State College PA 814 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/... Fairly active mid to late afternoon with isolated severe reports along with marginal heavy rain and flooding of poor drainage areas in parts of the Mid to Lower Susq River Valley. All areas had been well worked over by late afternoon and rainfall transitioned to more homogeneous light to locally moderate by early evening. Quasistationary upper level trof over the central GLAKS and Ohio Valley was helping to pool tropical PW over the Delmarva and southeast Piedmont regions this afternoon and evening...and lifting weak shortwave over PA is pushing the back edge of large shower and thunderstorm complex east of my area early this evening. To the west where instability remains...a broken line of showers and storms is targeting the southwest corner of PA...and isolated nearly stationary activity is lined up just northwest of the northwest corner of Warren County. This activity will continue to dissipate as the evening wears on...as previous forecaster mentioned that the NCEP HRRRV2 appears to get 80 percent of the rain out of our area by about 0500 UTC. Expect isolated at worst coverage after midnight with most areas remaining dry overnight...but with areas of fog forming. Expect many areas to get below one mile visibility in the pre dawn hours lasting through 7 AM. && .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 /00Z SUNDAY THROUGH THURSDAY/... Rain tapering off to sct showers 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. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Grumm NEAR TERM...Grumm/DeVoir SHORT TERM...Grumm LONG TERM...Watson AVIATION...Fitzgerald

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