Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 291634 AFDCTP Area Forecast Discussion National Weather Service State College PA 1234 PM EDT Thu Sep 29 2016 .SYNOPSIS...
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Showery conditions will prevail through tonight...with additional moderate to locally heavy rainfall possible over the higher elevations of the southern tier of central Pennsylvania through early Friday. Only minor flooding impacts are likely across the southern portions of central PA. Unsettled weather with occasional lighter rain showers will persist into the weekend with a gradual drying trend by early next week.
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&& .NEAR TERM /THROUGH TONIGHT/...
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Shaved away northern swath of counties from Flood Watch at this time...as overnight and morning amounts of one to a little over 2 inches fell in these areas and additional amounts should not bring a threat for flooding. Farther south, the 2.5 to 3.5 inch amounts that occurred across the southern tier make those areas suceptible to any persistent upslope or convective showers over the next 24 hours which could add another 1 to as much as 2 inches in some spots. Therefore the Flood Watch is being continued there. ...Previous discussion... Dry slot with high clouds peeling off to the east spells transition to low topped open cellular activity propagating from southeast to northwest today...a more showery regime with times of little or no rainfall and other times with brief moderate to heavy rates accumulating a few tenths of an inch at time. Strong upslope flow still moderate PW transport along with some elevated instability will maintain a favorable environment for heavy rain/efficient rainfall processes through this afternoon, while increasingly diffluent flow aloft supports some training bands in addition to the trend to low topped open cellular character. As the upper low settles a little further south, backing flow should shift the heavy rain focus back toward the upslope regions of the Laurel Highlands this afternoon into tonight. Still expecting 2-4" over the remaining flood watch area with locally 5"+ possible aloing the east-facing slopes and highest terrain. Very dry antecedent conditions resulting in 3-6hr FFG values of 4+ inches along with below normal stream flows should help to mitigate flooding to some extent, however if the higher end amounts are realized flooding impacts/runoff issues could become more serious.
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&& .SHORT TERM /FRIDAY THROUGH SUNDAY NIGHT/... The upper low continues to double back to MI on Friday before slowly tracking eastward into the Lower Great Lakes over the weekend. Strong E-SE LLJ and above normal PW along with associated forcing on east/southeast side of upper low favors scattered to numerous lighter rain showers through the period. The mid range models are keying in on a mid level short wave trough that could possibly increase rainfall rates and amounts through Central PA as it is coupled with the LLJ and the PWATS. && .LONG TERM /MONDAY THROUGH WEDNESDAY/... The trend for early next week is toward dry weather as the stubborn upper low is finally is kicked to the northeast by upstream amplifying trough over the Nation`s mid section. High pressure should regain control of the large scale pattern. FWIW the 29/00z GFS is much faster vs. the ECMWF with the projected path of TC Matthew, with the system nearing the NC coast by Thursday morning. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/... Increasingly moist easterly flow will will produce low cigs and rain across central Pa today. Model soundings and latest SREF output support predominantly IFR cigs through this evening at the higher terrain airfields, including KBFD, KUNV, KAOO and KJST. At the lower elevation airfields, predominantly MVFR cigs are expected today at KIPT, KMDT and KLNS. However, periodic IFR is likely this morning associated with bouts of heavier rain. Outlook... Fri-Sat...Low cigs/showers likely, mainly w mtns. Sun...AM low cigs possible. Mon...Showers/cig reductions possible at KBFD. && .CTP WATCHES/WARNINGS/ADVISORIES...
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Flood Watch through Friday morning for PAZ025-026-033>036-064- 065.
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&& $$ SYNOPSIS...DeVoir/Steinbugl NEAR TERM...DeVoir/Steinbugl SHORT TERM...Ceru/Steinbugl LONG TERM...Steinbugl AVIATION...Fitzgerald

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