Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 271055 AFDCTP Area Forecast Discussion National Weather Service State College PA 655 AM EDT Sat May 27 2017 .SYNOPSIS... Low pressure will ride to the south of PA this morning and keep a warm front just south of the state today and tonight. The warm front will try to work to the north as a cold front approaches the region on Sunday. The cold front will pass through on Monday morning. Low pressure will stall over northern Ontario mid-week and create a slightly cooler than normal and unsettled stretch of weather. && .NEAR TERM /UNTIL 7 PM THIS EVENING/...
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Lightning passing close enough to include a mention for the next hour or two. Prev... Cirrus and lowering cloud cover are moving in from the west. The convection which has been producing these clouds has just about dissipated as it slides to the SE just north of a warm front. The residual showers/anvil rain will pass through the SW portion of the CWA this morning. Dewpoints overhead and over MD/WV are only in the lower to mid 50s, and stability here argues against mentioning the T word for the morning despite the lingering presence of T in Central OH. Sprinkles will fall in the Laurels through 6 or 7 AM before the more-likely time for rain which is between 7 and 10 AM. The rain should slink to the SE and dissipate through the morning. It will be either gone or off to the east of the area by noon. Places N of FIG-UNV-SEG will likely stay dry, and POPs will be held below 30pct there. But, we will still mention some as the flow could still make some sprinkles up that-a-way. The afternoon looks nice with lots of sunshine in the northwest, but a bit of a struggle will be had to get sun through the clouds in the south and east. The proximity of the warm front just south of the state will mean some cloudiness is expected to linger across the S. Will keep just a 20-30 POP S of the Turnpike for the aftn. The chc for thunder does exist along the MD border, so we will just mention it only there for now, as SPC does just nick us with MRGL risk mention for any aftn convection. Maxes will be within a deg or two of 70F. So, take a break from heating/cooling the house today. Get out and enjoy an afternoon picnic.
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&& .SHORT TERM /7 PM THIS EVENING THROUGH 6 PM SUNDAY/... Clearing across the north this afternoon and evening will not last too long as the northerly flow from NY will bring some lake-related clouds in from the north. The low level flow will be more from the SE in southern PA (north of the warm front). This could allow crud (a.k.a. low stratus clouds) to creep in from the south/east. The more-likely places to see the low clouds will be right along the MD border and up into the Laurels where upglide due to the elevation change will help aid in cooling and condensation. Mins will be in the u50s S and l-m50s elsewhere. Will start to mention a little DZ possible in the SW, but keep POPs almost nil tonight and Sun AM. As the flow becomes more southerly in advance of the storm approaching from the west, the chance for storms increases on Sunday afternoon. The destabilization will be easiest in the east where less low clouds are expected, but the deeper moisture is off to the west and the dynamics are even farther to the west. PWAT goes above 1.5 inches in the west by the end of the day Sunday. Will ramp POPs up in the west through the aftn, leaving the east in chc or less POPs. && .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... A quick transition to increasing deep layer moisture and higher PWAT air of 1-1.25 inches will occur late Sunday. A large-scale trough and increasing upper level divergence (associated with a lead upper shortwave in the west/SW flow) will lead to a fairly large area of moderately strong uvvel and a widespread moderate rainfall along and ahead of a cold front. GEFS Probs for GE 0.50 inch of rain/24 hours ranges from 50-80 percent across the wrn mtns of PA...to generally less than 50 percent across the eastern half of the state. This translates into very high POPs for measurable rain (90 percent or more) across the western half of the CWA, to between 70 and 90 percent across the south-central mtns and Susq Valley. 12Z EC and 12z GEFS are in very good agreement on the timing/location of the north/south sfc cold front during the afternoon hours Monday across the eastern half of the state with weak deep- layer ridging and drying for Monday afternoon and night. Dry conditions expected Tuesday morning before significant cooling aloft accompanies a pair of short waves late Tuesday and later Wednesday. POPs during this midweek period will be painted as chc - translating to scattered showers with preference for the majority of the QPF (albeit quite light at that)to be across the typical west-nwrly flow upslope prone areas of the Laurel highlands and NW mtns. The chance for any thunder will be very minimal Tuesday through Thursday. Generally dry NW flow occurs late in the week into next weekend as a 1020 sfc high over the upper midwest Friday evening builds SE twd the region. Pops Thur night through Fri night will be 30 percent or less. After our bout of coolish weather with temps several Deg F below normal Sunday and Monday, GEFS mean temps rebound back to near or slightly above normal (even under slightly cooling 850 mb temps) for Tuesday through at least Thursday. ECENS mean temps are several deg warmer than the GEFS and Nat`l Blend of Models temps. leaned closer to the cooler solutions based on the few-svrl deg C of cooling aloft with near to slightly below 850 mb temps. && .AVIATION /12Z SATURDAY THROUGH WEDNESDAY/... Low clouds at BFD should break for a period of partial clearing (increasing high clouds) which may result in brief period of IFR fog. Clearing is already observed at UNV/IPT with a period of fog also possible at these sites before mid-high clouds overspread the area toward daybreak. Radar and satellite trends indicate upstream convection in OH/nrn WV is weakening and will continue to do so as it slides into the SW 1/2 of the airspace between 10-18z. MVFR restrictions are possible at JST/AOO this morning while other sites remain VFR. Precip should decrease in coverage over the southern airfields through the day but clouds may linger into the evening. Fog may become a concern tonight into Sunday morning based on latest guidance. .OUTLOOK... Sun...AM fog possible. Evening showers/reduced cigs possible west. Mon...AM showers/low cigs possible. Tue...No sig wx expected. Wed...Slight chance of showers/reduced cigs. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Dangelo NEAR TERM...Dangelo SHORT TERM...Dangelo LONG TERM...Lambert AVIATION...Fitzgerald/Steinbugl

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