Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 170037 AFDCTP Area Forecast Discussion National Weather Service State College PA 737 PM EST Mon Jan 16 2017 .SYNOPSIS... A warm frontal system will approach the region tonight and Tuesday, followed by a cold front Tuesday night and early Wednesday. High pressure will follow and bring mainly dry conditions with temperatures several degrees above normal from the middle of the week into the weekend. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... MRMS RALA showing just a few spotty showers falling across central Pa at 00Z associated with developing WAA east of storm system over the Miss Valley. Watching surface obs closely and do see a couple 32F mesonet readings at 00Z across the Laurels/south central Mtns. With another batch of showers approaching, may need to issue a SPS for this area to cover possible icy spots. Based on upstream obs expect precip remain very spotty/light through at least 06Z, then steadier precip slated to overspread the region from the west late tonight, as shortwave and associated low level jet arrive. All latest model guidance suggests the main freezing rain threat will be over the higher terrain of northern Pa, with a diminishing risk in the valleys and over southern Pa. Will therefore make no changes to current freezing rain advisory, but will monitor temps across southern areas for a possible expansion. QPF will be light so amounts of ice are not expected to be significant, but as we have seen several times in the past few weeks, even a little ice on untreated surfaces can cause significant problems. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH 6 PM TUESDAY/... A steady rain will continue Tuesday morning, as the strongest WAA accompanies passage of low level jet. SREF and NAM both indicate the possibility of lingering icing through mid morning across the high terrain of northeast Pa. The mid level shortwave and associated low level jet are progged to shift east of the area between 18Z-21Z, causing rain to taper to spotty drizzle. Surface warm front is progged to push into the Laurel Highlands during the afternoon, pushing temps into the 50s down there. Elsewhere, readings expected to top out in the 40s most places and the upper 30s over the Mtns north of Williamsport. I kept POPs near 100 pct Tuesday based on latest GEFS/SREF probs and overall favorable pattern of anomalous PWATS and strong lg scale forcing ahead of shortwave. Blend of model QPF ranging fairly close to a third of an inch tonight/Tuesday. && .LONG TERM /TUESDAY NIGHT THROUGH MONDAY/... Winds turn westerly behind the system by Wednesday morning as flow turns more zonal, but with no real cold air in sight, temps will remain on the mild side and above freezing during the day. Ridge re-establishes itself over the eastern U.S. for late in the week, as mild SW flow persists over the midwest. Guidance suggests energy will dive south along the west coast eventually helping to strengthen the building upper ridge over the east. We`ll be on the eastern side of this, so subtle shortwaves sliding into the Midwest will bring varying amounts of cloudiness to the west (less in the east) with low end chances for light showers. Another wave approaches/lifts into the OH valley late next weekend into next Monday. Again, temps could be marginal at the start of pcpn overnight Sunday for some ice or snow, but the bulk of pcpn looks to be rain at this point. && .AVIATION /00Z TUESDAY THROUGH SATURDAY/... 21Z TAFS sent. Band of showers to the north, could see some precipitation aloft earlier, as I was leaving to come to work. Further to the west and south, more in the way of showers. At the current time, temperatures are above freezing, but dewpoints are low, and ground temperatures are still cold. Thus still have the potential for freezing rain, especially on untreated surfaces and cold objects. Earlier discussion below. MVFR ceilings remain over my SERN terminals a weak SSE low level flow has kept the moisture locked in over the area. Elsewhere ceilings generally above 5000` prevail as overall cloudiness continues to increase from the west. Restrictions are likely to develop/return during the evening with widespread MVFR to LIFR conditions a good bet by late evening through Tuesday as rain gradually spreads across the airspace. There will be a risk for freezing rain, mainly over the northern 1/2 of the airspace between 05-15Z Tue. Outlook... Wed...MVFR/IFR west; MVFR central to VFR southeast. Rain showers west ending Wed ngt. Thu-Fri...No sig wx. Sat...Sub-VFR developing with the approach of a warm front. && .CTP WATCHES/WARNINGS/ADVISORIES... Freezing Rain Advisory from midnight tonight to 10 AM EST Tuesday for PAZ004>006-010>012-017>019-037-041-042-045-046- 049>053-058. && $$ SYNOPSIS...La Corte NEAR TERM...Fitzgerald SHORT TERM...Fitzgerald/La Corte LONG TERM...Lambert/Gartner AVIATION...La Corte/Martin

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