Area Forecast Discussion
Issued by NWS State College, PA

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191 FXUS61 KCTP 270217 AFDCTP Area Forecast Discussion National Weather Service State College PA 1017 PM EDT Wed Apr 26 2017 .SYNOPSIS... A strong subtropical ridge over the western Atlantic will dominate our weather through Monday. A front will weaken as it moves into the ridge late Thursday triggering thunderstorms. Then ridge will build westward over the weekend. We will be on the warm, moist western side of the ridge most of the weekend. A classic dirty warm up with warm moist air and potential diurnal thunderstorms. Alas, a strong trough should bring cooler drier weather to the region for the second part of next week. && .NEAR TERM /UNTIL 9 AM THURSDAY MORNING/... All is on track. Dewpoint depressions very small and we should see some fog/stratus forming soon. High cloud debris to the west will drift overhead - mainly over the NW - so fog not as likely in the NW except in the deepest valleys. Prev... Have mentioned a bit more in the way of fog across the region overnight/Thurs AM. Late-day clearing has occurred. Light wind, good radiational cooling and pretty high (55-60F) dewpoints will likely lead to some fog/stratus - esp in the eastern half of the region. Prev... We can see some funny blue stuff above the stratocumulus clouds locally. The GOES-16 0.64 channel shows most of the high clouds are in our easternmost areas and points east. Still some low clouds trapped in the valleys but mainly just strato-cu. The clouds will slowly erode and the temperatures will slowly climb this afternoon. Most areas should approach if not top 70F. The extreme southeast will likely be the last area to see the sun so they may not quite get to 70F in some locations. One of those days where northwestern PA will be warmer than our southeastern areas. Enjoy the late afternoon and evening pleasant weather. Due to weak flow and increasing moisture there could be some patchy fog. But a relatively warm overnight. && .SHORT TERM /9 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/... Other than the fog/stratus around in the morning, it should turn nout to be a very nice/warm day on Thursday. Many areas will top 80F. The POP, CAPE, and PWAT fields all suggest a front approaches from the west in the afternoon. Noted the 12Z GFS is slower and our superblend is drier than previous runs. No real QPF in our region until around 2100 UTC and by 0000 UTC it gets to central PA and dies. The GEFS is not in yet. Clearly any showers/thunderstorms will most likely be in the late afternoon or evening hours. Only modest CAPE where the LLJ is the strongest. In the 600-900JKG-1 range. Better CAPE in some models/members to southeast where there is less lift and weaker winds. The front is moving into a strong ridge and it is a bit moisture starved. Overnight Thursday into Friday showers end or die out in central areas. A bit cooler and drier overnight Friday into Friday AM. The PW is normal to below normal and the 850 hPa temps are closer to normal to a tad above normal. There is no CAPE to speak of. Friday looks potentially like a really nice warm late April day. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... High amplitude upper pattern to start the period will become more zonal by Days 2/3 as a vigorous trough and strong cold front swing through the region on Monday, bringing cooler conditions through the middle of next week. The region remains on the western periphery of a strong western Atlantic upper ridge, which leaves us susceptible to daily mainly diurnally driven shwr and tstm chances Saturday and Sunday. Continued to utilize a NBM/ECENS/WPC blend for max/min temps and POPS which maintained good continuity with previous fcst. While both weekend days feature a chance of showers and thunderstorms, most of the time will be dry and warm with highs both days ranging through the 70s in most places. Saturday may crack 80 over much of the southeast third of central PA. Max POPS during the extended period remain centered on Monday/May 1st as the aforementioned cold front crosses the Appalachians and continues toward the Atlantic seaboard. A severe weather threat may evolve downstream from the OH Valley into the Mid Atlantic late Monday before temperatures decline to near normal behind the cold front for next Tuesday and Wednesday. && .AVIATION /02Z THURSDAY THROUGH MONDAY/... A nice evening outside. VFR conditions this evening will prevail. However, some lower CIGS and visibilities later, given clear skies, recent wet conditions, and light winds. Expect poor conditions to burn off by mid to late morning, as winds pick up and the strong late April sun prevails. Did not go quite as high as guidance with winds at IPT Thursday afternoon, this area not quite in the gradient yet at 00Z. Also strong winds often pick up there just after 00Z until late evening. Some showers and perhaps a thunderstorm across western areas by 00Z Friday, as a cold front moves eastward. Outlook... Fri...No significant weather. Sat-Sun...A few showers possible. Mainly dry with VFR conditions for much of the time. Mon...Showers and thunderstorms likely. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Grumm NEAR TERM...Grumm/Dangelo SHORT TERM...Grumm LONG TERM...DeVoir AVIATION...Grumm/Martin

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