Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 222357 AFDCTP Area Forecast Discussion National Weather Service State College PA 757 PM EDT Mon May 22 2017 .SYNOPSIS... A cold front will push to the east of Central PA this evening. High pressure then builds in. However, a storm moving up the East Coast and could brush southeastern PA with a little rain on Tuesday. It will then be rather unsettled with many chances for rain through the rest of the week. Temperatures will be fairly close to normals. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... Precip has finally exited the east and winds have now gone light. sKies will partially clear across the central mountains while the northwest becomes mostly clear by late evening. Clouds will hang the longest over the east/southeast...at least until 06z before much improvement. Mins will range from the lower 40s north to the mid 50s southeast. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH 6 PM TUESDAY/... Major trend is toward a lower chc of rain in the SE on Tuesday. The NAM is very dry and the wet (a few hundreths) GFS and EC keep any precip to the S of the turnpike. We will start to weight the forecast toward less clouds and less chc of precip on Tues. Maxes will actually have a chance to overachieve on Tues with lots of sun in the northern and central counties. 70s widespread with m70s in the north. && .LONG TERM /TUESDAY NIGHT THROUGH MONDAY/... Trough for Tue night positioned further to the west (over IA/MO) in latest guidance, which will delay approach of surface low pressure area and keep trend of mainly dry conditions in Central PA for Tuesday night and Wed morning. But unsettled weather is on the way. Potent shortwave slides through the trough for Wed, as surface low deepens over the Ohio Valley. With sharpening trough working eastward, low and occluding front will lift across PA Wed night and Thursday bringing periods of rain/showers and chance for an embedded thunderstorm in an otherwise dreary day. By Friday, the low lifts to our NE as trough axis lifts through. Though the day should bring gradual improvement in the weather, highs Fri could end up several degrees below current guidance in CAA NW flow, a thicker low-level cloud deck and potential for light showers/drizzle - esp NW half of CWA. Sat should bring a return of brighter skies, albeit briefly, and may end up being the nicest day of the long weekend as weak ridge propagates through. Clouds will already be on the increase Sat afternoon and persist into Sun and Mon as a warm front develops over the Ohio Valley (with low pressure gradually organizing over the Midwest). Proximity of this frontal boundary along with deepening trough over the western Great Lakes will bring potential for showers Sun and Mon. Plenty of uncertainty in strength/placement of main weather features across model guidance during this time however, so forecast details remain somewhat elusive for late weekend. && .AVIATION /00Z TUESDAY THROUGH SATURDAY/...
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A slow moving cold front, located just west of IPT and THV at 00Z, is pushing through central Pa this evening. West of the front, drier air has arrived and confidence in VFR conditions through tonight is high. East of the front, stratus with cigs around 1kft cover much of eastern Pa at 00Z. Models indicate the front will eventually clear the entire forecast area by around midnight. However, radiational cooling, combined already low dewpoint depressions and light wind, will likely yield areas of late night fog across southeast Pa late tonight. Near term model data suggest IPT will likely see a strong enough push of drier air this evening to preclude significant fog issues overnight. However, LNS appears likely to experience IFR conditions overnight and MDT is in between with about a 50/50 pct chance of fog later tonight. Any fog across eastern Pa will burn off around or shortly after 12Z, with a high confidence forecast of VFR conditions across most of central Pa for the rest of the day. The only tricky part to the forecast is the possibility of very light rain, perhaps not even reducing the cigs below VFR, over the southern tier of the state. Would estimate about a 20 pct chance of late day MVFR cigs at the southern airfields, including JST,AOO,MDT and LNS. .OUTLOOK... Wed...Evening rain/low cigs possible, esp JST/AOO. Thu...Rain/low cigs likely. Fri...Showers/MVFR cigs NW. VFR SE. Sat...No sig wx expected.
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&& .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Dangelo NEAR TERM...Dangelo/DeVoir SHORT TERM...Dangelo LONG TERM...Lambert/RXR AVIATION...Fitzgerald

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