Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 270604 AFDCTP Area Forecast Discussion National Weather Service State College PA 204 AM EDT WED JUL 27 2016 .SYNOPSIS... A weak front will remain nearly stationary just south of the Commonwealth through Wednesday. High pressure will continue through mid week with warm and dry conditions. An area of low pressure approaching from the west is likely to lift through the region on Friday. && .NEAR TERM /UNTIL 6 AM THIS MORNING/...
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The overnight will be fair and dry with comfortable humidity over most of the area. H5 shear axis working on deep layer moisture pooling along and south of the Mason Dixon line to produce isolated showers now pushing through the Laurel Highlands. Added slight chc mentions for light showers through the overnight across the southern tier. Quiet elsewhere.
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&& .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM THURSDAY/... Rich deep layer moisture will remain pooled south of the Mason Dixon through Wednesday, providing dry conditions overall. Clouds will be most prevalent across the south, closest to the front and once again, a stray shower or thunderstorm cannot be ruled out right along the border, especially in the afternoon. Highs Wednesday will be a few ticks higher than Today across the north and generally unchanged south...and will range from the mid 80s north to the lower 90s southeast. && .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/... In the medium to long-range period...conditions slowly revert to near normal in temp and precip as several chunks of short wave energy in the westerly flow aloft helps to carve out a mean 500 mb trough axis over the Glakes and Ohio Valley region during the Thu-Fri timeframe. The peak in unsettled weather (with perhaps some periods of down- right rainy conditions) occurs Thursday night and Friday as a well-defined wave of sfc-850 mb low pressure lifts ENE out of the Ohio Valley and heads across the I-95 Megalopolis. Followed a blend of EC/GEFS/superblend and NBM guidance for that particular 24-36 hour period to arrive at likely pops for rain and scattered TSRA. Some uncertainty in timing and areal coverage of the convection led us to undercut the NBM by 10-20 percent for now, recognizing issues with large scale model convective parameterization schemes (and subsequent exaggeration of the areal coverage and broader qpf amounts) means that we`ll likely see more concentrated areas/bands of heavy convection, compared to the model depicted, larger cold season stratiform look to the precip shield. Portions of Southern and Central PA...close to the track of the 1006-1008 mb sfc low will likely see some localized heavy 1-2 inch,12-24 hour rainfl amounts by Friday afternoon...with even the potential for some pinpoint heavier amounts from embedded TSRA, as a tongue of 2 inch pwat air lifts north and wraps cyclonically into sern PA and the Lower Susq Valley. For later Friday through the upcoming weekend, a large area of high pressure (1020-1024 mb) near the border of southern Quebec and Ontario will try to push drier air south into the Mid Atlantic Region. Another...apparently weaker wave of low pressure at the sfc and aloft lifts NE out of the Ohio Valley over the weekend and brings an enhanced chc for showers. Slight diffs in timing/location exist between the EC/GEFS and NBM guidance. However...the target period for the best chc of showers and isolated to sctd TSRA appears to be late Sat into Sunday. Afterward, heights begin to rise from the southwest, accompanied by a ridge of surface high pressure building east into PA with mainly dry conditions and a rebound in temps for early next week. && .AVIATION /06Z WEDNESDAY THROUGH SUNDAY/... All terminals are VFR and will continue into the overnight before more patchy fog forms late night into the early hours of Wednesday. Any areas of late night fog will lift and dissipate within an hour or so of sunrise. Southern areas may see a stray shower or thunderstorm pop up in the afternoon Wednesday. OUTLOOK... THU-SUN...Mainly VFR. SCT PM SHRA/TSRA. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...La Corte NEAR TERM...Ross/DeVoir SHORT TERM...La Corte LONG TERM...Lambert/Gartner AVIATION...La Corte/Gartner

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