Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 211938 AFDCTP Area Forecast Discussion National Weather Service State College PA 338 PM EDT Sun Apr 21 2024 .SYNOPSIS...
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An upper level trough with unseasonably cold air aloft will drift through eastern Canada and the northeastern states to close out this weekend. A widespread frost or freeze is expected across portions of the Commonwealth that have started the growing season recently across Central and Southern PA, as high pressure moves overhead and the sky clears. After a sun- filled Monday, clouds increase and thicken up on Tuesday with showers returning to the forecast for late Tues through Wed. Another round of cold weather is in store for late Wednesday into Friday morning, before temperatures moderate for next weekend.
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&& .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... *Freeze Warning for the Ridge and Valley Region and Middle Susq Valley with temps as low as 25 to 32F, while a Frost Advisory has been posted for the Lower Susq Valley with mins of 33 to 35 and some 30-32F mins possible in the coldest rural valleys. Widespread, multi-layered and predominantly non-precipitating clouds kept temps nearly 10 deg F below normal in many locations with highs limited to only around 40 across the ridgetops of the North and West and mid 40s to low 50s respectively, from the Central Mountains to the Lower Susq Valley. Drier air advecting east in the wake of a weak, secondary cold front that extended from near KELM, SSW to KUNV and KCBE will slowly break up the clouds late this afternoon across the NW zones, between 22-23Z throughout much of the Central Ridge and Valley Region and 01-02Z over the Lower Susq Valley. Clearing skies will follow for tonight with temps dropping to the quite chilly levels noted above. && .SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/... Surface high pressure building in from the Ohio Valley will crest over the Appalachian Mountains on Mon. Temps will rebound nicely Mon aftn. 8H temps rise a bit back to near 0C. All this should help temps peak in the 50s over most of the area and lower 60s in Central and SE valleys where the best warming will occur via a light to moderate WNW wind. Vertical mixing up to around 6 kft agl will bring the likelihood of lower dewpoints than model guidance (by a few to several deg F). Clear skies early Monday night will be followed by increasing (but mainly thin) cirrus late Monday night early Tuesday. Low temps early Tuesday should average about 3 deg F warmer than early Monday, which should diminish the threat for sub-freezing conditions, but won`t eliminate the potential for frost. && .LONG TERM /TUESDAY THROUGH SUNDAY/...
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Tuesday will feature milder temperatures. Models still agree on timing of showers around 00Z Wed. Some variation in the amt of phasing of cold fronts later Wed. Either way, very cold air over Hudson Bay not that far away. A hard freeze possible across the north and west Wednesday night and again for Thursday night. While Thursday night might be a few degrees warmer, lighter winds would lead to more potential for frost. Only the far southeat areas both nights might stay just above freezing. Even in the southeast, rural areas could see frost or freezing conditions away from the larger urban areas on either night. Temperatures moderate by the weekend. EC still shows more upper level ridging, which would maybe hold most of the showers to the north and west of our area. However, large scale pattern shows some variation from model to model. Overall the large scale pattern supports wetter than normal conditions overall. Also an interesting note. 12Z EC really cranks up the low off the southeast coast. Something to watch.
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&& .AVIATION /20Z SUNDAY THROUGH FRIDAY/...
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VFR conds are expected to continue through 00Z Monday with high (> 90%) confidence. Some brief borderline or high end MVFR CIGS will occur INVOF KBFD through 22Z. Stratocu, topped by Altocu will have bases mainly between 045 and 060 this afternoon across the Ridge and Valley Region, with BKN-OVC CIGS based AOA 10000 FT AGL in the SE. West to WNW winds will gust between 15-20 kts across the Central and NW Mtns, in the wake of a weak cold front crossing the region. Winds will be notably lighter across the Susq Valley until picking up by 5-10 kts for up to several hours late this afternoon/evening in the wake of the Cfropa. WNW Winds diminish to under 6 KTS overnight and skies clear out. Outlook... Mon...No sig wx expected. Tue...Slight chance of evening showers/cig reductions NW Mtns. Wed...Showers move in west-to-east from rain early, continues throughout the day. TSRA possible SW late PM. Thu...Clearing as high pressure builds into the area. Fri...Mainly dry, but increasing clouds late.
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&& .CTP WATCHES/WARNINGS/ADVISORIES... Freeze Warning from 2 AM to 8 AM EDT Monday for PAZ019-025>028- 034>036-045-046-049>053. Frost Advisory from 2 AM to 8 AM EDT Monday for PAZ056-057-059- 063>066. && $$ SYNOPSIS...Lambert/Dangelo/Martin NEAR TERM...Lambert SHORT TERM...Dangelo LONG TERM...Martin AVIATION...Lambert

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