Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 211057 AFDCTP Area Forecast Discussion National Weather Service State College PA 657 AM EDT Fri Apr 21 2017 .SYNOPSIS... A frontal system will move through the Commonwealth this morning and early this afternoon followed by high pressure. An upper level cut off low will form over the Tennessee Valley late this weekend, and could end up bringing a storm up the East Coast in the first part of next week. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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Nice rope/line echo on the radar mosaic this morning running from BFD-PIT. Just isold shra along it right now, and no clearing until well behind it. Have tweaked near term slightly to move the eastern showers faster to the east, and near term temps and dewpoints upward slightly. Prev... Widespread showers across the area are devoid of thunder as of 4 am. No specific areas of heavy rain, so flooding not a concern at this point. These showers are on track to exit the area in just a few hours, which should create a little break in precip before the cold front, which appears to almost be to the PA-OH border, moves across. Not much precip expected with the front as the WV loop plays out little moisture left in the NW third of the area. However, residual moisture and mid-day timing of the front will make sct showers after it gets past UNV/AOO/IPT where it will pass around or shortly before noon. Have left a mention of thunder as well with some CAPE generated by the models. Far SErn towns are in a MRGL risk for severe. Little convergence will occur at the sfc as the front passes through there, though. Maxes could near 80F in the far srn tier, and 70s for a good chunk of the area. But, we need to clear out the clouds - and this likely won`t happen until after the front passes. The central mtns and mid-Susq Valley should have enough sun after FROPA to rise into the 70s. So, the bigger bust potential lies in the SE.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SATURDAY/... Skies may clear out for a very short time this evening, but clouds will likely close back in with NW flow and a digging trough moving across the lower Grrrreat Lakes. 00Z NAM does make a push for light rain/showers late tonight and in the first half of Saturday. Will make POPs just CHCs for the south, as GFS is certain that the precip will stay well to our south with EC also less-bullish on precip north of the Mason-Dixon. Mins tonight will be mild again, but highs on Saturday will be about 5 degs below normals with a decent amount of clouds moving across from the south and sub-freezing 8H temps in the northlands. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... With a cut off low progged to form over the Mid-MS and TN Valleys this weekend, it is very difficult to be certain in many facets of forecast. The differences in model solutions show up even before the long term starts - as the NAM is farther to the north with precip than all other models. While this is usually cause to discount that one outlier, the close time horizon makes me think we should give it some creedence. In general, the flat flow aloft in place before the low gets to our longitude should keep most of the precip to our south. Then, the changes from the last forecast cycle get quite substantial. The low creeps northward as it swings to the east of GA and keeps just off the coast early in the week and may precip in off the ocean a`la a Nor`easter. However, this storm does not deepen, nor slow without a big high to the north. A frontal boundary should remain to our north/west for much of the week, but may creep close enough to make showers/storms. Warm air then seems to establish itself once again pushing temps near/above 80 late in the week. && .AVIATION /12Z FRIDAY THROUGH TUESDAY/... A cold front will push southeast across the region this morning, accompanied by showers, as well as low CIGs in some locations. BFD, MDT and LNS already experiencing IFR CIGs at 10Z and latest model guidance indicates they are likely to remain in the IFR/LIFR category until after 12Z. Borderline IFR conditions are possible at JST early this morning, while UNV, IPT and AOO should see no worse than MVFR conditions. Improving CIGs expected by late morning, as drier air flows into western Pa in wake of the cold front and low clouds mix out ahead of the front in eastern Pa. Model soundings support widespread VFR conditions by early afternoon. However, an afternoon shower/thunderstorm could result in a brief reduction at MDT/LNS as the cold front comes through around 20Z-21Z. Generally VFR conditions and a diminishing northwest breeze are expected tonight, as a ridge of high pressure builds in. However, model soundings do indicate the chance of MVFR CIGs forming at BFD after about 03Z. Outlook... Sat...AM low CIGs possible at BFD. Sun...No sig wx expected. Mon...Rain/low CIGs possible southern Pa. Tue...Rain/low CIGs possible. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Dangelo NEAR TERM...Dangelo SHORT TERM...Dangelo LONG TERM...Dangelo AVIATION...Fitzgerald

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