Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 261900 AFDCTP Area Forecast Discussion National Weather Service State College PA 300 PM EDT Fri May 26 2017 .SYNOPSIS... An upper low is sliding off to the northeast and leaving a cool northwest flow in it`s wake. Weak ridging will move in but many chances for showers and a few thunderstorms are seen through the holiday weekend. A cold front will pass through on Monday. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
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Upper low over New England will slowly lift away from the region into the weekend. Nw streamers of light showers will diminish through the evening hours with breaks in the clouds expected overnight. However water vapor imagery shows several short waves within flat flow to the west of PA that will bring several chances of showers into the weekend.
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&& .SHORT TERM /6 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/...
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Approaching wave should give way to renewed light rain Sat morning mainly across the southern part of the state. A dry Sat aftn and early Sunday will give way to more rain Sunday afternoon region wide. The other operational models are also generating what looks to be an MCS upstream. The 06Z NAM has some convection just scooting to the south of the area, and it is mainly on Saturday. The EC is also placing a high QPF over the upper OH valley and into the Mid-Atlantic on Sat morning. There is a little better consensus on the timing and placement of convection for the short term, so we will nudge the POPs up a bit in the SW for the late tonight and Sat time frame.
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&& .LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/... A lower-amplitude but moderately strong westerly (zonal) mid level flow will set up in the wake of the departing upper trough with modest height rises/weak will ridging aloft into the weekend. A warm front is progged to extend east from surface low in the western Ohio Valley to the mid-Atlantic coast on Saturday. Central PA should reside on the north/east fringe of high instability convective corridor/MCS type pattern expected to evolve from the central and southern Plains to the southern mid- Atlantic coast into Saturday night. The greatest risk for scattered thunderstorms remains over the SW 1/3 of the CWA which is consistent with previous fcsts. SPC has introduced a MRGL risk into this area for D3. The remainder of the area should see a mainly dry start to the holiday weekend but will maintain slight chance POPs. The large scale pattern will evolve into a broadly cyclonic flow regime by Monday with upper trough parked over the Great Lakes and southeast Canada into midweek. The aforementioned warm front will lift north across the area on Sunday followed by a series of weaker cold front associated with shortwave trough rotating around parent upper low centered to the south of Hudson Bay. Ensemble blend still supports max POPs on Sunday/Sunday night into Monday with some additional shower opportunities into midweek as series of shortwaves rotate around mean upper trough. Temps should average near normal/seasonal climo to close out the month of May. && .AVIATION /19Z FRIDAY THROUGH WEDNESDAY/...
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Generally VFR bkn-ovc conds will persist into the overnight as nw flow continues across the airspace. Sprinkles to light rain showers will affect some airfields, but anything heavy enough cause sub vfr reductions will be brief. Remnant meso/convectively enhanced wave tracking east across the Ohio Valley should thicken clouds back up by Saturday morning. Confidence remains low on the evolution of this system given limited predictability and continued above avg. spread in the model guidance including high-res CAMs. Models are usually too far north with MCS type activity so it looks like the best chance for light showers would be over the far SW airspace 06-12z. .OUTLOOK... Sat...Chance of rain with sub-VFR possible. Sun...Showers likely with sub-VFR especially Sunday night. Mon-Tue...Scattered showers and a few Tstorms possible. Wed...VFR early with tsra accompanying a cold fropa late.
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&& .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Gartner NEAR TERM...Gartner SHORT TERM...Dangelo/Gartner LONG TERM...RXR/Steinbugl AVIATION...Gartner/Steinbugl

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