Area Forecast Discussion
Issued by NWS State College, PA

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715 FXUS61 KCTP 240915 AFDCTP Area Forecast Discussion National Weather Service State College PA 515 AM EDT Sun Sep 24 2017 .SYNOPSIS... A ridge of high pressure at the surface and aloft will keep the region dry through mid week. A trough of low pressure will bring cooler, more seasonable weather to end the upcoming week. && .NEAR TERM /THROUGH TONIGHT/... Nighttime blended images show the tendrils of valley fog growing over the Northern and South-Central Mountains. It`s all pretty much a carbon copy of the last several nights where we will start off the day with the areas of fog, ending up with plentiful sunshine and some late season summer-like warmth. There will be a noticeable increase in humidity today with dewpoints creeping into the mid 60s, resulting in more uncomfortable conditions than we have seen recently. Highs will be quite warm with some highs nudging 90 in some locations over the Susq Valley. It will remain mild overnight tonight with dewpoints making it feel a little humid. && .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 /09Z SUNDAY THROUGH THURSDAY/...
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As of 5 AM, fog gone at BFD. No big changes to 09Z TAFS. Earlier discussion below. Looking at mainly VFR conditions today. Some fog at BFD, but variation in obs would indicate that fog is more like ground fog. Mainly VFR conditions will continue well into mid week. Patchy valley fog will be possible for a couple hours near sunrise each morning, mainly over the northern mountains. .Outlook... Mon-Thu...Patchy AM valley fog possible. Otherwise VFR conditions.
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&& .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...La Corte NEAR TERM...La Corte SHORT TERM...La Corte LONG TERM...La Corte AVIATION...Martin

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