Area Forecast Discussion
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922 FXUS61 KPBZ 190909 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 509 AM EDT Tue Sep 19 2017 .SYNOPSIS... Generally warm and humid conditions will prevail for the next week across the area. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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Easterly boundary layer flow bringing maritime air farther west toward the ridges has allowed for the blossoming of stratocumulus along the eastern slopes of the CWA overnight, as well as toward DuBois. This has also allowed for dewpoints to start to tick up in the rest of the CWA as an even more dank boundary layer flows westward. Local dewpoints have been surging into the low to mid 60s across the area as a result. If clear skies were in the cards like the last couple of nights, this would likely mean abundant fog, however a different large scale scenario is playing out currently. High clouds are starting to slowly advance eastward into the majority of the area vis-a-vis convective blow off. The wave responsible for this convection to our west will be rapidly weakening as it drives into the teeth of the resident high pressure over the area over the next day or so. Multi-model projections suggest some showers should wander into central Ohio by Tuesday afternoon, however east of there the ridge should hold sway fairly convincingly. Thus, realistically almost the entirety of our area should remain largely dry other than a renegade shower that would try to develop given the moist boundary layer in place. With said moist boundary layer, cumulus development should again be fairly efficient once insolation gets going. Thus, cumulus over the eastern CWA overlaid with the high clouds moving in from the west will yield no better than partly sunny skies anywhere in the CWA through the majority of the day. However, given a very warm start and continued warm advection off the deck, highs should largely rise back into the 80s for most locations. Fries
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&& .SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY NIGHT/... While the front continues to struggle to advance eastward through tonight and into Wednesday, the attendant mid-level circulation and weakening cold pool will give it a whirl on Wednesday. GFS/EC guidance suggest it should start to slink SE as is weakens rapidly from afternoon into evening, and the bulk of the mid-level cooling is likely to remain to the SW of the area as it transits SE and falls apart. With that in mind, a chance/slight chance mention of rain showers will remain in the forecast for Wednesday afternoon/evening, especially over eastern Ohio and northern West Virginia. With the passage of the wave Wednesday, high pressure will again resume control with steady warming into the latter half of the week. Fries && .LONG TERM /FRIDAY THROUGH MONDAY/... Deepening troughing over the western CONUS and amplified ridging over the eastern CONUS will yield strong warm advection into the Ohio Valley through the weekend and beyond. This will be especially true as surface high pressure slowly trudges from directly overhead to ever-so-slightly east of the area by early next week. This will increase mixing potential, decrease any easterly moisture fetch into the area over the ridges, and yield a surge in 850 mb temperatures toward +17 to +19C for several days. As a result, highs in the lower elevations will jump at least toward the mid 80s, if not higher, and even in the higher terrain, upper 70s will be possible. With high pressure in control, and ridging amplifying overhead, no rainfall is anticipated during the long term or beyond. Fries && .AVIATION /09Z TUESDAY THROUGH SATURDAY/...
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MVFR/local IFR conditions in fog are possible at a few ports this morning, though increasing high clouds has limited this potential. Any fog should mix out after sunrise. VFR conditions with diurnal CU and increasing mid/high clouds are expected for the rest of the TAF period as a weak upper trough approaches. Clouds could limit fog potential again tonight/Wed morning. .Outlook... Other than local morning fog, no widespread restrictions expected through Sat with building ridging.
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&& .PBZ WATCHES/WARNINGS/ADVISORIES... MD...None. OH...None. PA...None. WV...None. && $$

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