Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 210525 AFDCTP Area Forecast Discussion National Weather Service State College PA 125 AM EDT Fri Oct 21 2016 .SYNOPSIS... A storm system will move into Western Pennsylvania later today and this evening. The associated cold front will move slowly across the state tonight and Friday. Windy and much colder weather will move in for the weekend with the first bout of lake effect and upslope rain and snow showers Saturday into Saturday night. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... Serious flooding ongoing from southern Centre County ENE through southern Clinton County as a stripe of 4 to 6"+ of rain has fallen since 900 PM Thursday evening. Water rescues are ongoing in Howard and customers are trapped in the Milesburg McDonalds where Dual Pol estimates of 7.2" have been indicated. Now hearing 911 traffic of rock slide in Lewis Township/Lycoming County as of 115 AM EDT. Training persists and heavy rain threat is concentrated from eastern Centre County through central Clinton/Lycoming Counties through 3 AM and beyond...with an additional 2"+ expected in many areas. FLood Warnings continue in a stripe from central Centre County to the Sullivan/Lycoming/Bradford County border. Additional heavy rain...but much lighter than the flooding rains which have occurred across the central mountains...will be targeting the NW Mountains in the pre dawn hours...thanks to strengthening upper jet entrance region which will support strong deep layer frontogenetic forcing moving slowly across the forecast area, through the first half of Friday. The front and area of rain will progress slowly eastward overnight by morning. && .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM SATURDAY/... There`s good consensus that the wavy front will have cleared at least the western half of the forecast area by mid day to be east of the entire forecast area by nightfall. Showers along the front will transition onto a steady moderate to heavy soaking rain as the front passes. The wind will shift to the NW and become gusty along with steady or falling temperatures after the frontal passage. By late day we should see the rain finally starting to taper off and become more showery. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... A major change in the weather pattern is expected to occur early in the period which could yield the first taste of snow over parts of Central Pennsylvania. An anomalous upper level trough will close off and take on a negative tilt, with a deepening coastal surface low tracking from southern New England north and west into eastern Quebec. Strong cold advection on the backside of the low along with 100-150m height falls and dynamic cooling within a pivoting deformation axis could result in a rain/snow transition Friday night into Saturday morning. The 20/12Z operational EC/GFS/NAM/CMC generate a coating to 1 inch of snow over parts of the Alleghenies and Laurel Highlands. Confidence in accumulation is still low but odds would seem to be increasing. For now will continue to mention rain/snow in the wx grids with no accums. A seasonably cold and brisk northwest flow will grip the area into the weekend with lake effect and orographic rain and snow showers likely over the Northwest Mtns and Laurel Highlands on Saturday. There is still a low risk for coating into Saturday night with accums very hard to come by during the daylight hours this early in the season. 25-35 mph wind gusts will add an additional blustery chill to below normal temps. GFS/EC/CMC all show a fast-moving low diving through the Great Lakes and Northeast into early next week. There is better agreement with this system embedded in the WNW flow aloft passing to the north of the area with max POPs over the far northern tier. This feature will reinforce the cold air aloft at least into Tuesday before strong warm advection commences through midweek. The models show a low near the Great Lakes by the end of the period with some hints a at a cold air damming pattern at low levels with high pressure retreating into New England. Overall not much pcpn expected Mon-Wed. Temperatures will be noticeably colder by the weekend with highs in the low 40s to mid 50s on Saturday. Expect some moderation on Sunday followed by a steady to cooling trend with readings averaging near to below normal through next Wednesday. && .AVIATION /05Z FRIDAY THROUGH TUESDAY/...
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Adjusted 06Z TAF package for current radar. UNV and IPT near the back edge of the heavier showers and storms. Another hour or so for heavy storms. Next batch of rain later tonight into Friday will be in the form of more of the way of rain, instead of showers and storms. Rain could linger into Friday evening, so did not try to end rain too fast in 06Z TAFS. The convective type of rain we had so far will give way to widespread showers and lower ceilings and visibilities later tonight into Friday, as a cold front moves into the area. Front will be slow to move east of the area before late Friday. Outlook... Sat...Scattered showers with restrictions NW. Brisk NW wind. Sun...No sig wx. Mon...Mainly VFR. MVFR with rain showers possible NW. Tue...No Sig Wx.
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&& .CTP WATCHES/WARNINGS/ADVISORIES... Flash Flood Watch through this afternoon for PAZ004>006-010- 011-017-024-033-037. && $$ SYNOPSIS...La Corte NEAR TERM...DeVoir/La Corte/Tyburski SHORT TERM...La Corte LONG TERM...Steinbugl AVIATION...Martin is the U.S. government's official web portal to all federal, state and local government web resources and services.