Area Forecast Discussion
Issued by NWS State College, PA

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325 FXUS61 KCTP 040221 AFDCTP Area Forecast Discussion National Weather Service State College PA 921 PM EST Sat Dec 3 2016 .SYNOPSIS... High pressure will slide quickly off to the east on Sunday. A weak frontal boundary will pass through Sunday night. Another storm system will affect the area during mid-week. && .NEAR TERM /THROUGH SUNDAY/... Widespread stratocu will persist through overnight as deep cyclonic flow continues over the region. Well-aligned flow on an approx 310 deg axis in the low levels will maintain several narrow bands of light snow/rain showers across the NW half of the CWA. Pops in the chc to low likely category will be limited into this evening across mainly the higher terrain to the north of I-80, though some very light rain and snow showers will reach about 20-30 miles south at times with QPF of 0.01 or 0.02 possible in a few locations. a light additional coating of snow is possible at elevations over 2000 ft MSL, otherwise, sfc temps are too warm and precip rates generally to light. Any clearing of the lower/stratocu deck tonight will be topped by increasing cirrostratus, then altostratus from the SW. Temps will be cooler tonight without so much wind to keep us well-mixed. Expect lows in the m-u 20s across the mtns, and generally lower 30s elsewhere. && .SHORT TERM /SUNDAY NIGHT THROUGH 6 PM SUNDAY/... Flow relaxes tonight as sfc ridge slides overhead for Sunday morning. Some decrease in cloud coverage is expected overnight, but it turns right around during the day on Sunday. High/mid/low cloud progression will darken things again wherever breaks/clearing does occur. The E/SE will stand the best chance for complete clearing. Temps will be cooler tonight without so much wind to keep us well-mixed. Biggest challenge in this cycle is what kind/how much precip falls Sunday night from the passage of a weak front. All the models and most of the GEFS members crank out 0.05-0.20 inches of QPF for Sun night as the feature is carried steadily through by mainly zonal flow. Most of the precip should be snow, but it is not likely to stick in many places SE of the Allegheny Front. Just the highest hill tops of the SE may get a dusting. For a few runs, a weakness exists in the QPF right through Central PA from W-E. This seems to be a disconnect between the moisture and the left-exit region of a 150kt jetlet which passes right over the state. Temps are marginal for accums, and QPF is light. Have drawn 1-2 inches across the nrn tier of counties. It is a nighttime event, and temps in the nrn tier are much more likely to be sub-freezing all night. && .LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/... The ridge moving to the east will be followed by a large cyclone emanating for a large upper level low moving into the northern Great Lakes region. There is decent agreement in bringing the upper low up through the Ohio Valley on Tuesday as a shearing out shortwave and diffuse the surface low. Unless cold air damming traps enough chilly air in the low levels to make for some freezing rain, the precip type with this midwest system looks to be mainly rain. Have raised POPs into the categorical range as it seems unlikely that we will get missed. The end of the week brings some model disagreement with the GFS/GEFS being faster than the ECMWF with the next large upper trof and frontal system. Either way, precip looks like a good bet around the Thu/fri period as all solutions eventually bring this trough through. So predictability is increasing, but timing issues remain. Best bet for precip at this point is mainly rain over the SE as decent push of warm air lifts ahead of the system, with a rain/snow mix further north where warm air will not infiltrate as much. Behind the trough, looks like a chilly weekend in store with a potential sharp dropoff in temps. && .AVIATION /02Z SUNDAY THROUGH THURSDAY/... Extensive cloud cover continues across Central Pennsylvania this evening. Typical WNW flow regime, with MVFR ceilings across the Western and Northern Mountains, with VFR ceilings across central and eastern airfields. Lake effect streamers continue to affect KBFD and vicinity, with the chance of conditions dipping into IFR category from time to time. High pressure approaching from the west will cause snow showers to diminish overnight. Additionally, the high building in will allow winds to continue to diminish overnight. Light precipitation moves in Sunday Night. Mainly rain in the southeast...a rain/snow mix in central areas...and mainly snow in the north and northwest. Outlook... Sun...Morning restrictions in mountains, then VFR. Sun Night...Mixed rain/snow event with restrictions. Lowest conditions in the mountains north and west. Mon...No sig wx expected. Tue...Mixed precip/low CIGs possible, especially late. Wed...Lingering low CIGs possible. Thu...Mixed precip/low CIGs possible. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...La Corte/Lambert NEAR TERM...La Corte/Lambert SHORT TERM...Lambert LONG TERM...Gartner/RXR AVIATION...Jung

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