Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 241415 AFDCTP Area Forecast Discussion National Weather Service State College PA 1015 AM EDT Sun Sep 24 2017 .SYNOPSIS... Unseasonable late-September heat will continue in central PA through early week. Mostly dry weather will also continue with just an isolated shower possible in spots on Wednesday. A pattern change will bring cooler, more seasonable fall-like weather back to the area for second half of the week and into the upcoming weekend. && .NEAR TERM /THROUGH TONIGHT/... GOES-16 visible satellite loop shows valley fog dissipated with abundant sunshine across the area. It will feel more like summer than early fall with more noticeable humidity and max HX values in the low 90s for some areas. No reason to deviate from persistence in this pattern with respect to high temps. It will be mild tonight with minimum temps running about +15 degrees above climo average. Some fog in the valleys otherwise clear. && .SHORT TERM /MONDAY/... Monday will see more of the same, some fog early, followed by a sunny and unseasonably warm afternoon. && .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... The blocking high that has been responsible for the recent extended spell of dry and anomalously warm conditions is forecast to start breaking down by the middle of the upcoming week when shortwave energy sliding along the US-Canadian border finally chews away at the high heights and brings some cooler air eastward. In the meantime the future of Maria is still not quite set in stone. The latest ECENS has shifted a bit to the right, but the GFS/GEFS/NAEFS and Canadian Ensemble all bring the center of Maria perilously close to Cape Hatteras by late Wednesday. With the strength of the ridge north and east of the hurricane, it seems plausible that it will continue on a NNW track at least closely threatening the coastal waters, before the northern stream shortwave finally paves a path for a hard turn east before the storm hits 40 deg north. As it stands now, it looks like the first chance we will have to see any rain might be Wednesday with a weakening cold front that is destined to fall apart in the unfavorable shear on the north side of the sprawling hurricane slated to be off the Mid Atlantic coast by that time. There are still differences in how much of a trough carves out over the NERN US for the end of the week into next weekend. The 00Z ECMWF seems to be an outlier closing off a potent upper low over the Gr Lakes before dropping it into Pa by Sunday. The other ensemble suites show troughing, but no closed circulation. I leaned toward the blended MOS for generally low POPs starting Friday associated with the weak troughing that consensus is leaning toward. The surest bet will be that the week will end on a significantly cooler note than it starts. && .AVIATION /14Z SUNDAY THROUGH THURSDAY/... VFR prevailing with some local restrictions in valley fog possible during the predawn and early morning hours Monday. .Outlook... Tue...Patchy AM valley fog possible. Otherwise VFR conditions. Wed...Mainly VFR, isolated PM shower possible. Thu...No sig wx. && .CLIMATE... Record-challenging late-September heat through early week. Daily high temperature records from 9/24 through 9/26: Bradford: 82 in 1961, 83 in 2007, 79 in 1998 Williamsport: 90 in 1961, 89 in 1970, 92 in 1900 Harrisburg: 97 in 1970, 93 in 1970, 91 in 1970 Altoona: 91 in 1970, 90 in 1970, 88 in 1998 && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Steinbugl NEAR TERM...Steinbugl SHORT TERM...La Corte LONG TERM...La Corte AVIATION...Steinbugl CLIMATE...Steinbugl is the U.S. government's official web portal to all federal, state and local government web resources and services.