Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 181541 AFDCTP Area Forecast Discussion National Weather Service State College PA 1141 AM EDT Mon Sep 18 2017 .SYNOPSIS... A persistent ridge of high pressure at the surface and aloft will maintain fair, warm and generally dry weather during the entire upcoming week, and likely through the weekend as well. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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Another morning with fog and low clouds spilling over the valleys. Satellite shows that the fog is starting to erode in areas where there are no clouds above the fog. We can also see the start of cumulus formation on the exposed ridges. Unlike recent days with scattered afternoon/early evening convection across the SE half of the state, it appears that the best Cape and main focus for any scattered showers will be across our NW zones and to a lesser degree over the Laurel Highlands where a narrow ribbon of sfc-based Cape around 1000 j/kg is likely on the eastern periphery of relatively high PWAT air sliding in from the Ohio Valley just ahead of a slowly advancing and weakening cold front. Afternoon highs will show a slight increase from the past few days with maxes expected to reach the u70s to low 80s.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/... Another mostly clear night is on tap with valley fog forming after midnight. Low temps will vary from the upper 50s across the nrn and wrn mtns to the L60s in the SE metro areas. Tuesday should once again begin with the locally dense valley fog, 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 east of the Delmarva coast) will likely brush our far SE zones. Based on model 700-300 mb RH fields, the rather thick mid and high cloud shield from the offshore storm will likely back in to cover the Susq Valley and point to the east during the late morning and afternoon hours Tuesday, likely holding down the temps a few to svrl deg F across that region of the CWA compared to recent days. Max temps elsewhere will continue to run 6-10F above normal for mid September. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... For much of this period, a 500 hPa ridge will dominate our weather. As Jose moves away to the NE, heights will rise and this should further dry us out for the second half of this week. The GEFS forecasts a closed 5880 m ridge over us with near +2 sigma above normal heights by Friday and Saturday which will translate to well above normal temps. Enjoy! && .AVIATION /16Z MONDAY THROUGH FRIDAY/...
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My western terminals are VFR with IFR/LIFR fog/low ceilings from AOO-UNV eastward. The reduced conditions will improve most slowly over the SERN portions of the flying area where clouds above the fog will retard heating and mixing. AOO-UNV will improve the quickest with VFR expected by or shortly after noon. Can`t rule out an isolated shower later today especially over the western 1/3 of the airspace. With little change the surface pattern with light/calm winds and relatively high dewpoints, anticipate return of sub-VFR low clouds and fog at most sites tonight into Tuesday morning. .Outlook... Tue...AM restrictions in low clouds/fog trending to VFR. Isold shower NW. -RA psbl far eastern airspace associated with Jose. Wed-Fri..AM restrictions in low clouds/fog; otherwise VFR with no sig wx.
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&& .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...La Corte/Lambert NEAR TERM...La Corte/Lambert SHORT TERM...Fitzgerald/Lambert LONG TERM...Lambert/Gartner AVIATION...La Corte/Steinbugl

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