Area Forecast Discussion
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000 FXUS61 KPBZ 271824 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 124 PM EST Mon Jan 27 2020 .SYNOPSIS... Crossing upper level disturbances will maintain showery precipitation in the forecast into Tuesday. Building high pressure will return dry weather and seasonable temperature by mid-week. && .NEAR TERM /THROUGH TONIGHT/... Lingering, shallow moisture in the wake of an earlier shortwave passage will support areas of drizzle and / or freezing drizzle through the period. Precipitation type will be dictated by surface temperature, and the best chance for freezing drizzle should be confined to areas north of the I-80 corridor and in the eastern ridges through tonight. Areas elsewhere, including the Pittsburgh metro area, should observe drizzle as surface temperature hovers above freezing through the remainder of this afternoon. Dry advection in shortwave ridging should diminish the widespread drizzle potential overnight. The exception would be for areas north of I-80, where lake-enhanced moisture maintains this potential. Similarly, upslope in the ridges should yield enough ascent to maintain areas of freezing drizzle overnight. As such, the Hazardous Weather Outlook highlights this threat as slick spots may develop along roadways and elevated surfaces. && .SHORT TERM /TUESDAY THROUGH THURSDAY/... The continued passage of weak shortwaves in northwest flow aloft will support mainly isolated snow showers through Tuesday evening, with only minor accumulation confined to the ridges. This is due to the lack of deep moisture through the dendriditic growth zone. Such shallow moisture evident in forecast soundings may support the development of areas of drizzle / freezing drizzle again Tuesday but have opted to allow later shifts to refine precipitation type with updated guidance. Despite precipitation type, overall precipitation accumulation will be minimal given such limited, available moisture. Precipitation chances will gradually end Tuesday night through Thursday as high pressure builds across the Ohio River Valley. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... Dry conditions will prevail through Friday under surface high pressure. A modest warming trend will be felt as flat ridging briefly visits in the mid- levels. The forecast for the weekend remains murky at this distance. A fairly stout 500 mb trough is expected to develop across the southern Plains late this week, but strength/timing details remain questionable, as does its level of interaction with other waves in the flow. For now, a scenario involving a low developing off of the Atlantic seaboard and moving northeast seems most likely, with a trailing trough developing over the Mississippi Valley/eastern CONUS providing rain and snow chances to our area on Saturday and Sunday. Temperatures will continue to run a bit above climatology. && .AVIATION /18Z MONDAY THROUGH SATURDAY/... IFR and MVFR conditions will continue through the TAF period as cold advection continues to advance from the NW. Brief light freezing drizzle cannot be rule out later this evening for DUJ/FKL with ground temps near or below freezing and lingering warm cloud tops. Quiet conditions should prevail during the early morning hours as high pressure builds over the Midwest. VFR conditions are expected to return late tomorrow night for some sites south and west of PIT as winds shift from the northeast. .Outlook... Quick moving shortwaves to our southwest and across the Great Lakes may return widespread restrictions late this week. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...None. OH...None. PA...None. WV...None. && $$

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