Area Forecast Discussion
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996 FXUS61 KPBZ 181039 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 539 AM EST Sat Feb 18 2017 .SYNOPSIS... Dry conditions are largely expected until the next frontal system crosses the region Tuesday afternoon and Wednesday. Well above normal temperatures are expected through the end of next week. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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Clear skies to go with the unseasonable warmth this morning. Later today the ridge axis will cross, bringing high clouds back to the area. These are ahead of a weak, and slow moving system that will approach from the southwest tonight. With the peak of the warm air overhead and ample sunshine through the early afternoon, temperatures will soar into the 60s for many locations. This could approach record warmth for several climate sites (see Climate section below).
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/... A fair amount of model consistency has been noted leading into tonight`s system, but latest guidance has slowed it`s evolution some. The 00z GFS is a bit of an outlier, tracking the low further north than it`s brethren. Outside of the GFS, the model consensus is leaning towards more of a southern track, keeping the best rain chances across southern WV. The forecast has been modified towards this trend, trimming the northern extent of PoPs and overcast skies. The low translates east of the area quickly Sunday. Another strong ridge begins to build into the Great Lakes, eroding clouds through Sunday evening. In the wake of the departing weak low, slight warm air advection will establish with the building heights. This will keep temperatures well-above average, but a few degrees below today`s expected readings. && .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... Given the track record of this "winter," we`ve quickly come to realize that it`s been easier to attain 60 degrees in the cold season than keep the daily maximum in the 20s. This extended forecast builds upon that annual premise, extrapolating it into the absurd. It isn`t a matter of whether or not every day in the extended forecast will be above normal, rather it`s a matter of the "degree" to which we blow normal away. Clustering of model and ensemble guidance is better than normal, which should be expected given the highly amplified, slowly evolving upper level pattern. As such, moderate ridging over the region early in the period will be tamped down a bit as a weak short wave trough centered around Tuesday night traverses the region. Because forcing associated with this short wave shears off to the north quickly, cold advection behind it will be virtually nil. As such, west-southwesterly flow aloft will only serve to continue the gradually warming trend aloft through mid- week. Fairly deep upper level troughing looks to dig continuously through the latter portion of the week over the southwestern CONUS. This will gradually turn the west-southwesterly flow aloft over the region into a progressively more amplified ridging pattern that first builds over the western Great Lakes then toward the northeastern states by Friday. As this occurs, the 850 mb thermal ridge will likely flop through the area late in the week ahead of showers and thunderstorms associated with the fairly deep system set to eject out of the southwest. As this occurs, temperatures will be set to skyrocket with 850 mb consensus values in the +10 to +12C range, which would suggest many areas may challenge 70 degrees by Friday. Colder air and a rapid changeover to snow showers will be likely going into next weekend as 850 mb temperatures look set to fall toward -5 to -10C by Saturday night. Fries && .AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
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VFR conditions expected to carry through the day as high pressure slides across the area. A passing low-level jet will keep a few hours of LLWS before mixing begins. Clouds will increase later today with the best chance of any precipitation or MVFR CIG restrictions at KMGW. MVFR CIG restrictions are then possible areawide Sunday morning. .OUTLOOK... The next chance for widespread restrictions will be with a Tuesday cold front.
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&& .CLIMATE... Record High Temperatures February 18: Pittsburgh, PA 66 (2011) Zanesville, OH 64 (2011/1994) Morgantown, WV 73 (1981) DuBois, PA 57 (1981) Wheeling, WV 60 (2008) New Philadelphia, OH 62 (1961) && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...None. OH...None. PA...None. WV...None. && $$

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