Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 270634 AFDCTP Area Forecast Discussion National Weather Service State College PA 234 AM EDT Fri Apr 27 2018 .SYNOPSIS... A weak storm system entering Virginia will move northeast along the coast Friday and into New England Friday night. An upper air disturbance will swing into the region from the Great Lakes Saturday and early Sunday. A stretch of fair weather with a warming trend will start Monday as high pressure builds over the Atlantic Coast. Above normal temperatures are likely for the middle of next week. && .NEAR TERM /UNTIL 6 AM THIS MORNING/...
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MRMS RALA loop at 06Z indicates the first drops of rain have begun to fall along the Mason Dixon Line over southern Bedford and Fulton counties. Based on upstream radar trends, have increased POPS to near 100 pct across the south central counties by dawn. Potent upper level shortwave and associated surface low will lift northeast across the Mid Atlantic region early this morning, spreading rain into the southeast part of Pa. HRRR simulated radar, which should perform well in a strongly forced scenario such as this, suggests rain will have overspread the area south and east of KJST/KUNV/KIPT by 10Z.
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Low pressure and associated shield of rain should lift northeast of the region by early afternoon. Bulk of model data indicates the back (western) edge of the rain will reach roughly from KJST to KUNV and KIPT. Model blended qpf indicates the band of heaviest rain will roughly parallel I-81, where around 1/3 of and inch is expected. By afternoon the eastern half of the forecast area should dry out, while focus shifts toward upper trough axis pushing in from the west. Some modest instability noted in model soundings across western Pa. where scattered showers and even a few tsra are expected ahead of approaching trough. After a cloudy morning across much of the region, expect a bit of brightening by afternoon, as surface low lifts aways. However, mainly overcast skies will hold temperatures below seasonal averages, with highs in the low 60s in most places.
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&& .LONG TERM /TONIGHT THROUGH THURSDAY/... A shot of arctic air will move into the area Saturday night and Sunday with 8H temps near -10C and 1000-500 thickness less than 530dam. The consistency across the models is pretty good with this mass field result, so confidence in cold temps and a gusty NW wind is high. The lake/8H temp difference will support SHSN at Saturday night/Sun AM across the far north and west. The fcst not bad, main change was to up winds longer on Monday, and lower dewpoints some Sunday into Monday, given the winds aloft and airmass source. With some clouds and a breeze Sunday night, this will help taper the risk of frost early Monday across the region. Will still be too breezy early Monday for burning brush and leaves. Better chance for that after Monday. Temperatures moderate Tuesday into Thursday, as high pressure moves east of the area. Given how dry it is over portions of the Great Plains, I did not rush higher dewpoints into too fast, given that as the source region of the warm up. Green up is largely controlled by nights with mild temperatures and higher dewpoints at night than we have seen. Only night that way was back in February. Need to stay above 50 degrees to get much response from the grass and many trees. Looking at some showers late Thursday, as the cold front moves into the area. Mean trough tries to kick back in after this warm up. Some hints it could be wet for several days, especially if the 12Z EC is correct. && .AVIATION /06Z FRIDAY THROUGH TUESDAY/... VFR will prevail through daybreak across much of Pennsylvania with cloud bases lowering from 25 KFT AGL to 8-10 KFT AGL around 08Z Friday. The exception will be over the southern few layers of counties, where a MVFR Nimbostratus deck (and the leading edge of a large area of light rain) will move in from the south during the predawn hours on Friday. Low pressure lifting up the eastern seaboard will likely spread rain and generally MVFR (to briefly high end IFR) Cigs and MVFR to VFR vsbys across roughly the SE half to two thirds of the state during the mid to late morning, and the mainly light rain will continue through the late morning hours Friday across Scent PA and the Middle Susq Valley, and into the mid afternoon hours over the Middle Susq Valley and Ncent Mtns. Outlook... Fri...Rain/low cigs possible, mainly eastern Pa. Sat...Showers, especially early. Sun...Breezy. AM low cigs/flurries possible W Mtns. Mon...No sig wx expected. Breezy early. Tue...No sig wx expected. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...La Corte NEAR TERM...Fitzgerald SHORT TERM...Fitzgerald LONG TERM...Martin AVIATION...Lambert is the U.S. government's official web portal to all federal, state and local government web resources and services.