Area Forecast Discussion
Issued by NWS State College, PA

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930 FXUS61 KCTP 170936 AFDCTP Area Forecast Discussion National Weather Service State College PA 536 AM EDT Sat Mar 17 2018 .SYNOPSIS... A weakening storm system will slide to the south of the state today with high pressure expected to build back in for the remainder weekend and the start of next week. A new storm system could affect the state during the Tuesday- Wednesday time frame. && .NEAR TERM /THROUGH TONIGHT/... Skies are mainly clear with just the first streamers of high cloudiness beginning to slide down over the region from the NW. The clear skies and light winds are making for a chilly night with temps in the teens and 20s. Satellite shows a low along the IA-MO border sliding east, with the associated frontal cloudiness shearing out to the east. The strong cyclone still in place over eastern Canada is keeping a deep NW flow well established locally, which will drive the approaching storm system off to our south today. Ensemble POPs are a bit higher than the HRRR supports, so I tried to downplay the chances for rain/snow/sleet over my Mason-Dixon line counties this morning into the afternoon. As of 4AM, the nearest precip hitting the ground is over SW OH. There is some concern for a bit of spotty freezing rain, but given the delayed onset time of the precip, the thinking is temps will recover enough to mitigate this threat. Right now I have a brief period of a light wintry mix mentioned. The latest HRRR and the 00Z SPC HREF suggests the best window of opportunity for some light precip over my southern zones will be from about 15-20Z. With expected highs in the mid 30s to mid 40s, any snow that falls will have a hard time accumulating. Drier air will reestablish by late in the day into the overnight. It will be unseasonably chilly once again with lows in the mid teens to mid 20s from north to south. && .SHORT TERM /SUNDAY/... Sunday looks fair as high pressure begins to nose in from the west. Highs will range from around 40 over the north to a couple of degrees either side of 50s along the MD border. Overall temperatures will average slightly below normal. && .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... The main weather maker of concern looks to arrive over the eastern US Monday night and continue into mid week. The GFS/GEFS are most aggressive with the northern extent of the precipitation shield. The ECENS tracks the primary surface low through TN before redeveloping it over SC and tracking it well south of the local area. This would lessen the threat of accumulating snow over central and northern PA and provide the biggest threat over the far southern portion of the CWA where it could be warm enough that a wintry mix cannot be ruled out. This time of year with marginal temps, we generally need good precipitation rates to keep it cold enough to be all snow and so far the indications are that several days out, this might be hard to come by. So in the extended products and Hazardous Weather Outlook we will do more in the way of hedging since it still very uncertain how the storm will evolve. The larger picture has the NAEFSBC advertising the Greenland block that has led to the first two weeks+ of March being cold and rather stormy in parts of the NE, to finally begin breaking down and the pattern becoming more mobile. Below normal temps are forecast to persist though mid week with a moderating trend or a return to more normal readings slated to return for the end of the week into next weekend. Spring Equinox is Tuesday at 1215 pm EDT. && .AVIATION /10Z SATURDAY THROUGH WEDNESDAY/... 09Z TAFS sent Some high and mid clouds today across the south. Any precipitation should remain south of JST and AOO. A weak area of low pressure will pass south of Pennsylvania today...possibly nipping KJST/KAOO with a period of light snow during late morning/early afternoon. Based on latest model output...believe the odds of vis reductions at KJST/KAOO are low. Thus have kept the forecast as VFR for now. If any precipitation did make it into south central would be out of the area by sunset. Some chance of more rain and snow for Tue into Wed...but bulk of the precipitation may stay out of our area...still several days out. Outlook... Sun-Mon...No sig wx expected. Tue...Rain/snow possible, mainly southern Pa. Wed...Snow possible, mainly southern Pa. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...La Corte NEAR TERM...La Corte SHORT TERM...La Corte LONG TERM...La Corte AVIATION...Martin is the U.S. government's official web portal to all federal, state and local government web resources and services.