Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 231523 AFDCTP Area Forecast Discussion National Weather Service State College PA 1123 AM EDT Sun Apr 23 2017 .SYNOPSIS... A frontal boundary will remain stalled to the south of the state into Monday as an elongated east/west ridge of high pressure drifts across the commonwealth. An upper level cut off low will form over the Tennessee Valley and will carry its associated surface low up the East Coast early in the week. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Abundant Sunshine and a light northeast to easterly wind will prevail through the afternoon with just an increase in in cirrus/cirrostratus occurring over the southern half of the state. Temps are one track to reach mid to late afternoon highs in the 60s at all locations, except for the highest ridges across the Laurel Highlands, where the mercury will top out in the mid to upper 50s. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM MONDAY/... It will remain dry tonight despite a weak front dropping down from the north which may touch the northern tier as it stalls and gets washed out. The upper low will deepen and cut off over the TN vly/SErn states through the short term period. Good moisture flow off the Atlantic and up from the GOMEX will lead to rain over the Mid-Atlantic. It will push slowly north against the high pressure over ern Canada and the NE US. Expect some rain to approach the MD border by sunrise Monday. But, it may not make much more northward progress through the daylight hours. Will keep the likely POPs along the MD border and taper to nil before I-80. Maxes Monday will be warmer in the N than the S, running from m60s N to m50s S. Rainfall does not look heavy on Monday, as the best moisture/easterly wind anomalies pointed to the south of the state and the sfc low will still be down near Myrtle Beach. && .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... The period of Monday Night to Tuesday Night will be dominated by the flow around a slow moving cut-off low which eventually will pass to our south and east. This system will bring clouds and light rain to the parts of our region for several days. The models are in fair agreement on timing and position of this low. Bands of precipitation should begin to streak through the region, mainly the east Tuesday morning. Timing and position of the low will change whether or not different portions of central Pennsylvania get precipitation. Have increased POPS for eastern PA. The gradient will be tight on any precipitation amounts. Once this system goes by large scale retrogression will put our region on the western edge of a relatively strong 500 hPa ridge and it will get warm fast. It should feel like summer by next Thursday. The potential for rain will be higher in southeastern PA and much lower in northwestern PA. Rainfall will likely be very light and the best chance for measurable rainfall will be in southeastern PA. Enjoy the mostly cloudy and relatively cool weather while it lasts. As the 500 hPa low fills and the attendant moves to our northeast the chance of rain should fall off Wednesday into Wednesday evening. Our 850 hPa temperatures will rise rapidly Wednesday and it should be noticeably warmer Wednesday relative to Monday and Tuesday. Thursday into Saturday the 850 hPa temperatures will be well above normal, mainly in the 14 to 16C range and we will be on the western edge of a rather impressive early season subtropical ridge. The GEFS and GEFSBC show a closed 5880 m ridge along the VA/NC/SC coast with +2 sigma height anomalies by Fri-Sat. Thursday through at least Saturday should be very warm and humid. We should have several days with high temperatures well into the 80s. Any precipitation after Wednesday will likely be in a more summer-like atmosphere so have kept thunder in all forecasts beyond Wednesday. The ridge will likely continue retrograding. If the NEAFSBC and GEFSBC are correct we could be looking at our first enduring period of warm weather from this coming thursday into the following week. && .AVIATION /15Z SUNDAY THROUGH THURSDAY/... Nice, VFR flying conditions will prevail through the afternoon today with just a gradually increase in high clouds across southern PA. winds will be from the NE to East at 5-9 kts in many locations, though some gusts into the teens will occur across the Laurels INVOF KJST. Some patchy light rain could push back into the southern tier counties of PA very late tonight into Monday, as a complex storm system forms across the southeast states and drifts slowly north up the eastern seaboard. Some rain could get into central areas on Monday, and perhaps into northern PA Monday Night. Potential for a wet day on Tuesday, as a complex low lifts northeast along the coast. Improving conditions for Wed. Showers and thunderstorms spreading eastward, along and ahead of a cold front on Thursday. Outlook... Mon...Patchy rain spreading slowly northward. Tue...Rain/low CIGs likely. Wed...Improving conditions. Thu...A chance of showers and Thunderstorms. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Dangelo/Lambert NEAR TERM...Lambert SHORT TERM...Dangelo LONG TERM...Dangelo/Ceru AVIATION...Lambert/Gartner is the U.S. government's official web portal to all federal, state and local government web resources and services.