Area Forecast Discussion
Issued by NWS State College, PA

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089 FXUS61 KCTP 281836 AFDCTP Area Forecast Discussion National Weather Service State College PA 136 PM EST Tue Feb 28 2017 .SYNOPSIS...
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Southerly wind today and Wednesday will continue to bring milder air and a bit more moisture into the region. Low pressure will move across the Upper Great Lakes and track north of Pennsylvania on Wednesday. Severe weather is possible on Wednesday in advance of a potent cold front slated to pass through late in the day. Much colder air is in store for late week, with sub-normal temperatures likely over the weekend.
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&& .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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Temps warmed into the mid 50s to lower 60s today under mostly sunny skies before mid clouds associated with a short wave trough spread across the region. This trough is responsible for the current convection advancing across WV early this afternoon. Southern mountains look to be on the northern edge of this rain area, with precipitation slipping into there this afternoon. Best chance for thunder will be along (but even more likely) south of the PA border. QPF is still expected to be rather light and any rain/showers will be spotty in the north.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY NIGHT/... Showers associated with the first wave will slide to the east this evening, and a more significant wave will roll into the NW later in the night. POPs high as many folks will get wet late tonight and through the morning on Wed. Dewpoints will still be rather low, especially in the NW, so thunder overnight and in the morning is not a certainty. Will include it as a slight chance for that time frame. The interesting and most-challenging part of the forecast comes in the second half of the day and evening on Wed. As has been advertised well over the last few days, the set-up will be highly similar to last Saturday wwith a strong cold front moving in from the west late in the day. SPC has upgraded to place the entire area into a slight risk for severe weather on Wed aftn/evening. Strong llvl winds and good height falls/cooling aloft are certainly in store. However, the wild card is the amount of sunshine which will occur and therefore how much heating/instability develops. The showers in the morning can do one of two things - either moisten things up, sufficiently raising the dewpoints and lowering stability and LCLs, or they may make low clouds linger long enough to keep it too cool for widespread severe parameters to be met. Most likely there will be lots of convection, but just how deep and how widespread the severe threat will be is in question. Have taken a small step to mention gusty winds with the categorical POPs drawn in the afternoon (and lasting into the evening in the SE). The cold front timing is pretty solid with a significant veering to the west and temp drop occurring about or slightly before sunset in the very late aftn W and evening E. The leading edge of the main surge of cold air may wait until a few hours after that. So the p-type will likely not turn to snow in the W until midnight-ish. Any accumulations Wed night will be very minor if any due to warm/wet ground and scattered nature of the shsn. Gusty west wind will occur as and after the front passes. values are up close to advy level on the ridges, but will keep them just below for the time being. && .LONG TERM /THURSDAY THROUGH MONDAY/... It will be turning noticeably colder Thursday as strong westerly post-frontal flow directs cold air into the area. A broad trough remaining over the Northeast U.S. on Friday will push off the coast by the beginning of the weekend. A clipper system associated with the final piece of shortwave energy embedded in the trough may bring a mix of snow and rain Thursday night into Friday with a light accumulation possible. The mean 500mb flow is fcst to flatten out a bit over the weekend with temperatures moderating nicely to above average after bottoming out on Friday. Overall, the pattern looks fairly quiet over the weekend and into early next week with another strong frontal system possible by March 7-8. && .AVIATION /19Z TUESDAY THROUGH SUNDAY/...
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VFR conditions across the region early this afternoon as mostly sunny skies fade behind advancing mid clouds associated with a short wave trough. This trough is responsible for the current convection advancing across WV early this afternoon. Southern mountains look to be on the northern edge of this rain area, with precipitation slipping into there this afternoon. Best chance for thunder will be along (but even more likely) south of the PA border. QPF is still expected to be rather light and any rain/showers will be spotty in the north. This evening, area of light rain looks to expand a bit further northward as warm front lifts through, poss to around I-80, with reductions developing for much of the region as moisture increases on increasing SW flow. Restrictions initially dip to MVFR with IFR settling in for most as light rain ends by 06z. Next up will be impacts from approaching potent cold front on Wed. SW surface winds pick up with strong to even severe storms becoming possible as a cold front moves eastward across the area during the afternoon and early evening hours. Outlook... Wed...Rain showers/Sub-VFR reductions. Breezy. LLWS likely. Scattered thunderstorms - some could be strong to severe. Wed Night...Strong FROPA early with gusty winds/tstms. Thu-Fri...Sub-VFR likely west in sct snow showers. NW winds. VFR elsewhere. Sat-Sun...No sig wx.
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&& .CLIMATE... With only one more day left in meteorological winter (Dec+Jan+Feb), it seems that we are currently running as the 4th-warmest winter at both Harrisburg (tie) and Williamsport. Today should be another above-normal day, which may push Harrisburg up to 3rd place, and Williamsport may get nudged up to a tie for or even an outright 3rd place. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Dangelo/RXR NEAR TERM...Dangelo/RXR SHORT TERM...Dangelo LONG TERM...Steinbugl AVIATION...Martin/RXR CLIMATE...

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