Area Forecast Discussion
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880 FXUS61 KPBZ 221206 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 806 AM EDT Sun Apr 22 2018 .SYNOPSIS... High pressure will provide dry weather and seasonable temperatures into Monday. Rain chances return by Monday night with approaching upper level low pressure. && .NEAR TERM /THROUGH TONIGHT/... Minor adjustments to hourly dewpoints to nudge a little closer to current observations, otherwise the forecast remains on track. Previous discussion... Weak troughing aloft, as well as RRQ jet dynamics, are responsible for the sheath of mid and high clouds across the area. The departure of the upper support plus dry advection from the north will help to gradually shunt the clouds south of the region with time, such that most areas should enjoy a mostly sunny afternoon. Tonight will be mostly clear as well, as a mid- level ridge axis crosses overnight. Warm advection will be fairly modest today, if present at all, but temperatures should be able to achieve seasonable levels both today and tonight. && .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... An upper low will slowly churn across the lower Mississippi Valley and then the Tennessee Valley by Tuesday morning, before lifting northeast and arriving in our area as a degenerating open wave Tuesday night. The models are in decent agreement with this scenario, with still some minor details on the arrival of moisture and isentropic lift. The arrival of light rain looks a bit quicker now though overall, and have reintroduced small PoPs to the southern counties Monday afternoon. Increasing rain chances Monday night then lead to at least likely PoPs areawide Tuesday and Tuesday night as the disturbance crosses. Low level southeast flow into the ridges during these latter two periods will lead to higher rain chances and QPF overall. The better moisture tap and forcing will lie off to our east and southeast however, closer to the Blue Ridge. Temperatures will max out a few degrees above climatology Monday before the rain arrives. Cooler temperatures due to the clouds and rain are figured for Tuesday. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... A followup shortwave will kick a cold front across the region on Wednesday, keeping temperatures a shade below normal into Thursday. Cannot rule out a few snowflakes mixing in Wednesday night/Thursday morning behind the front, as 850 mb temperatures could drop below 0C once again. A dry interlude is possible Thursday afternoon/evening in brief surface ridging. Precipitation chances return Friday and Saturday as another shortwave arrives. Some model solutions close this off into an upper low over or near our region, while others are more progressive. In any case, below normal temperatures should continue. && .AVIATION /12Z SUNDAY THROUGH THURSDAY/... Sfc high pressure should maintain VFR conditions through the TAF period. OUTLOOK... Periodic restrictions are likely Mon night through Wed with slow moving low pressure. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...None. OH...None. PA...None. WV...None. && $$ is the U.S. government's official web portal to all federal, state and local government web resources and services.