Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 241143 AFDCTP Area Forecast Discussion National Weather Service State College PA 743 AM EDT Sat Sep 24 2016 .SYNOPSIS... High pressure will move down from Hudson Bay into the northeastern states this weekend. Expect fair weather with seasonably cool temperatures over the weekend. A cold front will push through early in the new week and should make some rain late Monday into early Tuesday. Dry weather will return for the rest of next week. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Winds are north/easterly now all the way to the Turnpike, but the dry air is only about a third of the way into the CWA. The feature/thin-line on radar closing in on the RDA is most likely the real dry air as it`s passage coincided with a one-hour 7 degree drop in dewpoint in Wellsboro. This dry air will continue to slide south and west through the morning. Barely a tick on radar otherwise. But, a stray shower is still possible through mid- morning in the southern tier. Sky trends match the going forecast with almost all of the area cloudy at this point, but we can see the Finger Lakes on the IR satellite pics, and those breaks/that clearing should work southward through the morning. By sunrise the northern tier could be clear, but will hold onto patchy clouds there for a few hours. The clouds look like they could hang tough in the southern tier for much of the morning or even just past noon. Will then clear it out. Maxes should be 10-15F cooler than yesterday`s lofty temps. But, they will still be just at normal or a deg or two warmer. && .SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY NIGHT/... clearing will complete very early this evening and PWATs will be below normal under the subsidence of the advancing high pressure bubble. This airmass change will make it really feel like autumn as temps drop off into the m-u30s in the northern mountains, and 40s elsewhere. With the prolonged period of very much above normal temperatures, this will be quite a shock to some. There could be just a little bit of the north wind left tonight and a few wisps of high clouds. But otherwise, these conditions are very good for frost. It is also difficult to shake the idea of abnormal warmth from the forecast, as well. Forecaster bias tells me that it may not get quite that cold when temps got 5F higher than forecast at IPT yesterday. But, it is a new airmass. This may be a case where the current temp anomaly clouds forecaster judgment. Will mention patchy frost for now and stay barely on the high side of the MOS temp guidance for mins. Dayshift may have more certainty on frost formation. But the cold air draining into the river valleys will then set up a battle between the river valley fog and frost. These two phenomena are rarely coincident. Sunday should be stellar with low dewpoints, few clouds after the valley fog lifts, and temperatures almost normal. Some high clouds will slide down from the NW Sunday night. These may have a tiny effect on temps, but there may be a little bit of an east wind. Guidance says that it should be quite a bit milder in the west Sunday night vs. Sat night. Will stay close to these numbers. && .LONG TERM /MONDAY THROUGH FRIDAY/... Clouds increase Monday ahead of significant cold front headed our way. Recent guidance has hurried up with the timing of the front. Have adjusted things by 3-6 hours faster. This then puts the timing of showers during the afternoon/evening in the west. Will add a slight chc thunder in there due to the peak heating/lower stability possible with this timing. Certainty of rainfall for most of the area has climbed into the 60-70pct range. This will be much needed rainfall, centered on Monday Night. The front should be through by Tuesday morning. Will linger only chc POPs in the far SE and keep them in the far NW for lake-effect and/or cool air aloft instability showers for mid-week. Temps should stay very normal for the balance of the week - but the dryness returns for a long period. && .AVIATION /12Z SATURDAY THROUGH WEDNESDAY/... Post-frontal low ceilings ranging from LIFR to low VFR will gradually trend to widespread VFR by the afternoon. LIFR/IFR conditions at KJST should last at least through 14z. VFR with clear skies and light winds overnight could lead to some patchy fog by Sunday morning. Outlook... Mon...PM showers/Tstms with reductions possible. Tue-Wed...No sig wx expected. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Dangelo NEAR TERM...Dangelo SHORT TERM...Dangelo LONG TERM...Dangelo AVIATION...Steinbugl

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