Area Forecast Discussion
Issued by NWS State College, PA

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127 FXUS61 KCTP 190829 AFDCTP Area Forecast Discussion National Weather Service State College PA 429 AM EDT Tue Sep 19 2017 .SYNOPSIS...
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A ridge of high pressure at the surface and aloft will stay locked in place over Pennsylvania for the next 7 days. This dominant weather feature will provide fair, warm and generally dry weather throughout this entire period.
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&& .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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Another comfortable night/early morning with light wind as Central PA remains in the sweet spot of weather - between Hurricane Jose (spinning about 250 NM east of KORF) and a stalled out frontal boundary extending from the Lower Great Lakes to the Midwest States. The main weather maker this morning will come in the form of patchy dense fog across portions of north-central and northwestern PA where significant pockets of clear skies exist. Elsewhere, a slightly anomalous llvl easterly flow will push plenty of stratus clouds westward across the forecast area and act to minimize the thickness of any fog that does form. Min temps around sunrise today will be in the upper 50s to lower 60s...which will average around 10 deg above normal. Morning stratus and areas of generally light fog will be burning off to a partly-mostly sunny afternoon as the upper ridge axis continues to reside right over central PA. The western extent of the outer bands of showers associated with Hurricane Jose (that will be a few to several hundred miles east of the Delaware coast during the late morning and afternoon hours) will brush our SE zones where we`ll continue to play it safe and mention slight chc or chc pops with very low QPF (if any) of under one-tenth of an inch. With expected light rain and thicker cloud cover, temps will likely be suppressed a bit across that region of the CWA compared to recent days (but will still be 4-5 deg F above normal). Max temps elsewhere will continue to run a solid 6-10F above normal for mid September.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM WEDNESDAY/...
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LLVL flow will become light and northerly tonight as slowly weakening Tropical Storm Jose drifts to near the latitude of southern PA (40 deg N) by 12Z Wed. Expect much less in the way of stratus tonight and just some wisps of cirrus on the edge of Jose`s circulation, so it appears that locally dense valley fog will come into play once again after 06Z Wednesday. Min temps early Wednesday will be at least 2-4F lower than early Tuesday. A spectacular Wednesday is on tap with abundant sunshine, and just a few flat cu and thin cirrus to paint the otherwise azure blue sky. Max temps Wednesday will once again range from the mid to upper 70s across the higher terrain of the north and west, to the L80s in the SE.
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&& .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
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For much of this period, a 590 dam closed 500 hPa high will drift slowly out of the midwest states, and become centered over western PA by late this weekend through early next week. The GEFS forecasts showed this feature as a closed 5880 m ridge over us with near +2 sigma above normal heights Friday-Sunday, which will translate to well above normal temps. Enjoy! High temps over this several day period will be 10-15F above normal with little or no chance of rain through at least Monday. Lows early each morning will be consistently in the mid and upper 50s across the northern and western mtns, to lower 60s in the larger SE metro areas. Min temps may cool off slightly for this weekend thanks to deep dry air and a light N to NW llvl flow of drier dewpoint air at the sfc.
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&& .AVIATION /08Z TUESDAY THROUGH SATURDAY/... Increasing coverage of low stratus and fog will impact the airspace this morning with widespread MVFR to LIFR restrictions. Cut back on fog (increased visibility AOA 1-2SM) from previous TAFs with more emphasis on low clouds. The more challenging aspect of this forecast will be timing of improvement which should occur in the 14-16z timeframe. Model data, climatology and persistence support a high confidence of widespread VFR conditions from the afternoon into the evening. .Outlook... Wed-Sat...Patchy valley fog possible each morning. && .CLIMATE... Astronomical Fall/Autumnal Equinox begins at 4:02 PM Friday September 22, 2017. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Lambert NEAR TERM...Lambert SHORT TERM...Lambert LONG TERM...Lambert/Gartner AVIATION...Steinbugl CLIMATE...Gartner

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