Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 230846 AFDCTP Area Forecast Discussion National Weather Service State College PA 446 AM EDT Fri Sep 23 2016 .SYNOPSIS... A mainly dry cold front will pass through later today and tonight. Fair weather with seasonably cooler temperatures is expected over the weekend. Another cold front will push through early in the new week and could make some rain. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Lots of high clouds around the northern half of the area this morning. However, this moisture has no nearby connection to the surface and dewpoints are still in the m50s for the most part. Wind does come out of the west later today and could increase those dewpoints above 60F. The cold front seems to enter the state sometime before sunset. Most models do produce some very isolated showers later this afternoon or evening across the northern half of the area. There is an infinitesimal chance of a thunderstorm, but not worth mentioning T at this point. && .SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY/... All model data pushes cold front all the way through central PA tonight. But, without upper level support or even moderate moisture, we expect a mainly dry fropa for much of the area. Although cooler air will begin flowing in on a northerly breeze, that band of clouds along and just behind the front will keep things mild tonight - especially over the south - with mins between u40s in the northern mtns to around 60F in the south. If winds drop off to near calm across the north, could see some late night valley fog, while an active northerly breeze precludes fog issues elsewhere. Will not mention fog for tonight quite yet. The clouds should dissipate/slide southward Saturday morning and leave a mostly sunny day. Maxes will be about 10F cooler than Friday - right about normal to very slightly above normal. Sunday morning looks almost certain for fog in the valleys as temps drop another 10F from Sat AM and the air will be calm. Only the dryness of the airmass could preclude fog, but am fairly certain of fog. Sunday is another wonderful but dry day. The maxes may be a few degs cooler than Sat in the south, and may actually turn out sub- normal there. But similar and normal maxes will occur elsewhere. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... Models remain in good agreement in dry and seasonable weather this weekend as Canadian high pressure builds southeast into Pennsylvania. Some of the colder spots in north-central PA look to dip into the upper 30s Sunday morning, which is not unusual for this time of year. But some frost is possible. Main changes for the long term period were to account for seemingly good agreement on the passage of a cold front Monday Night. There looks to be some moisture with it as the sfc low slows down and occludes to our west. But, it could again dry up as it approaches the region. The deep upper trough/cut off low rolling through the inter-mountain west looks like it will ride northward a bit and deepen over the Upper Great Lakes mid-week, but then the crystal ball gets more cloudy. If the recent GFS solutions are to be believed, the upper low will drop into the Lower Lakes and perhaps stall again overhead. That would be a dark and unstable/showery time for PA during the middle-end of the week. The ECMWF operational run from 00z takes the low from the Upper Great Lakes pretty much straight to the east into eastern Canada. This would be a much brighter and milder outcome. Will allow for a little of both sides of the coin in the forecast with a low chc POP in the mid-week. It should be dry by Day8 even by the GFS progs. && .AVIATION /08Z FRIDAY THROUGH TUESDAY/... High clouds continue to push southeast across the northern airspace in advance of frontal boundary located over Lake Ontario. Localized brief restrictions in fog remain possible around daybreak. Widespread VFR expected for most of the period with a very low chance for an isolated shower across the northern 1/3 airspace this afternoon into early tonight along the cold front. Guidance is indicating post-frontal sub-VFR ceilings reaching the northern airspace late tonight into early Saturday and have added MVFR FM group 24/03-05z at KBFD/KIPT/KUNV. Outlook... Sat-Sun...Patchy AM fog possible with mostly clear days. Mon-Tue...Increasing risk for showers/thunderstorms ahead of cold front. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Dangelo NEAR TERM...Dangelo SHORT TERM...Dangelo LONG TERM...Dangelo AVIATION...Steinbugl

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