Area Forecast Discussion
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000 FXUS61 KPBZ 061916 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 216 PM EST Tue Dec 6 2016 .SYNOPSIS...
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Low pressure is expected to spread precipitation across the region through early tonight. A Thursday cold front will return snow shower chances and much colder temperatures for the end of the week and into the weekend.
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&& .NEAR TERM /THROUGH TONIGHT/...
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An upper level shortwave trough and associated surface low shifting across the Ohio valley through tonight will support widespread precipitation over the region while sufficient moisture is fetched from the Gulf and Atlantic. Strong warm advection aloft will result in mostly freezing rain where the advisory exists. Southeast flow will inhibit warming in these areas until the flow veers southwest later in the evening. Across the northeast zones, temperatures have warmed enough so that precipitation should occur as rain and/or sleet initially before changing over to all rain later this afternoon as the warm air regime continues. The NAM and hi-res models continue to diminish the development of snow due to lack of cold air and moisture around the mid levels. Thus, have reduced snow amounts through the period. The aforementioned lack of moisture can be observed through the water vapor imagery as dry air continues to push well into the Ohio Valley. The newest NAM and latest hi-res models depict this feature well and have therefore reduced QPF amounts through tonight. In addition, have slightly reduced total ice accumulation due to predicted relatively high rain rates through the rest of the period. The low level jet should allow for gusty winds across the ridges this evening but are expected to remain below advisory criteria. Steady precipitation will pull off to the east fairly rapidly by the late evening as the system shifts east.
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&& .SHORT TERM /WEDNESDAY THROUGH FRIDAY NIGHT/...
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Lingering low level moisture over the eastern zones may cause light precipitation early Wednesday. Otherwise, dry weather is forecast for as surface high pressure builds across the region briefly. The next cold front is still expected to cross on Thursday, bringing the coldest air of the season so far. Have increased PoPs for snow showers behind the front in the developing mid-level trough. Latest guidance shows favorable lake enhancement snow to develop mostly over the the north for a short period of time. After the initial onslaught of the cold front and blustery snow showers late Thursday, inversion heights will gradually lower and decrease the snow accumulation rate by late Friday. Nonetheless, stagnant low level moisture and lowering dendritic growth zone is expected to keep snow chances lasting through the start of the weekend, especially over the higher terrain. Temperatures will lower to below normal values by the end of the period and wind chill values are expected to decrease to near single digits.
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&& .LONG TERM /SATURDAY THROUGH TUESDAY/... The cold-supporting upper trough over the Eastern CONUS is progged to fill rapidly early next week as another low develops toward the Great Lakes. Flow over the Upper Ohio will thus deamplify and temperature moderate back toward the seasonal averages. Best precip chances look to be on Sunday night and into Monday as that Great Lakes low drags a front across the region. With the low-center forecast well north of the region, precip timing will depend on eventual frontal progress. Superblend guidance was used for long term forecast construction. && .AVIATION /19Z TUESDAY THROUGH SUNDAY/... Condition deterioration to eventual IFR can be expected today as low pressure spreads precip over the region. Most of that will be rain, but a wintry mix is anticipated at FKL and DUJ. ESE may also be problematic on the surface with gusts around 20kt with gradual veering as the system passes this afternoon and evening. MVFR cigs are likely to linger tonight in the residual moisture blanket and cooler flow behind the system, but building surface high pressure will support improvement to VFR on Wednesday. .OUTLOOK... Periodic restrictions are likely for the rest of the week as a strong cold front sweeps the region. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...Winter Weather Advisory until 10 PM EST this evening FOR MDZ001. OH...None. PA...Winter Weather Advisory until 10 PM EST this evening FOR PAZ074-076. WV...Winter Weather Advisory until 10 PM EST this evening FOR WVZ512>514. && $$

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