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000 FXUS61 KPBZ 180915 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 515 AM EDT Thu Apr 18 2019 .SYNOPSIS... Conditions will remain mostly dry until a low pressure system impacts the region early Friday morning and into the weekend. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Spotty showers have shifted east of the area with the supporting shortwave. Strong warm advection aloft is expected to increase stability today so convection chances remain low. Improved mixing with the rising sun is expected to support highs 15 to 20 degrees above the averages as well as gusty wind near 25 kt. && .SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY/... A few isolated rain showers may develop in advance of the approaching cold front during the late evening hours. The majority of precipitation is expected to come into our region by late Friday morning/early afternoon as the upper level trough, aligned with a sfc low, stalls over the Appalachian Mountains. Sounding analysis shows that while wind shear will be respectable high, close to 30kts at the low levels, instability will be hard to come by due strong warm advection aloft--CAPE values go no higher than 300 J/kg. If clouds break and temperatures have a chance to advance higher than expected, a few strong thunderstorms MAY form. The most likely region for these storms to develop will be southeast of Pittsburgh and the main threat would be wind damage. Due to the absence of a strong upper level jet downstream of this upper level low, it will take its time for this system to move out our region. It will continue to linger near West Virginia by Saturday evening. However, dry air moving through the mid-levels will help diminish widespread precipitation chances. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... The upper trough will finally shift east Saturday night, allowing showers to become more scattered. Multiple shortwaves embedded in a broad upper level ridge Monday through Wednesday may allow isolated rain showers to develop. && .AVIATION /09Z THURSDAY THROUGH MONDAY/... VFR conditions are expected to be marred today only by sfc gusts of 20 to 25kt as pres gradient and mixing in the incrsg warmth on sly flow improve. Expect llvl wind shear development tonight with llvl jet through the ern flank of TN Valley, to Mid OH Valley low pres. Overall condition deterioration with eventual restrictions and rain should be expected for Friday as that system encroaches on the Upr OH Region. .Outlook... Restrictions and showers are likely through the weekend as strong low pres traverses the region. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...None. OH...None. PA...None. WV...None. && $$

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