Area Forecast Discussion
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857 FXUS61 KPBZ 190408 CCA AFDPBZ Area Forecast Discussion...CORRECTED National Weather Service Pittsburgh PA 1208 AM EDT Sat May 19 2018 .SYNOPSIS... A series of disturbances will keep rain chances in the forecast through early next week. && .NEAR TERM /THROUGH SATURDAY/... An upper low across the Midwest is expected to open into a trough by Saturday morning. Weak shortwave support in southerly flow ahead of the low, and a weak warm front lifting N, should keep light rain chances across the area tonight. Maintained likely to categorical POPs mainly E of I 79 where the most favorable moisture and shortwave support is expected. The front and shortwave support should exit Saturday morning with rain chances diminishing. The Midwestern trough is progged to approach the Upper OH Valley region in the afternoon. Numerous showers/tstms are expected to develop as the trough approaches and convective thresholds are met. Marginal speed shear and instability could result in a few strong storms with gusty wind. && .SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/... Any storms that develop during the prime heating hours Saturday will weaken shortly after dusk. They won`t be diurnal driven, so will maintain chance pops through the night as the heart of the H5 trough axis crosses around 6Z Sunday. The columns dries out Sunday per differential anticyclonic vorticity advection and weak high pressure across the upper Great Lakes. Low pressure crossing IL/IA area will spread a warm front through the region Sunday night. No QPF is forecast at this juncture with the boundary. However, as H5 heights fall during the overnight hours, a decaying thunderstorm complex from the midwest could track across the area toward dawn. Elevated instability is not impressive thus do not expect more than brief heavy rain. && .LONG TERM /MONDAY THROUGH FRIDAY/... Highlights: - Weather Pattern Remains Active - Above Normal Temperatures - Finally a String of Two Dry Days by Week`s End Little to no change in the pattern the first part of the week. Southwesterly flow continues to pump low level moisture northward from the Gulf of Mexico while northwesterly flow aloft funnels mid level disturbances over the region. This means at least a chance for showers and thunderstorms through Wednesday. Instability will be present for potential strong storms, but of course this far out sky cover and residual boundaries are very challenging. Will focus likely pops during the time frame when good agreement exists on a passing shortwave trough. At this juncture it appears that will be Monday night into Tuesday. A break in the active weather by week`s end as a transitory H5 anticyclone traverses the area. Of course, the trend has been to push this back a day every cycle as stubborn northwest flow won`t depart. H8 temps will be in the 10C-13C range, thus values well into the 70s and lower 80s are expected for forecast highs. Overnight lows won`t be much different than the past several days with mid 50s to lower 60s being the norm. && .AVIATION /04Z SATURDAY THROUGH WEDNESDAY/... Lower than average confidence forecast through tonight as southerly moisture push continues to erode by dry air in place. Continuing to see the effects of the dry air on the lack of widespread precipitation shown by earlier model guidance. Adding to this is the strong easterly flow that exists, helping to shadow some of the low-level moisture across central ports of MGW/AGC/PIT. Some of this moisture is expected to push over the Ridges and result in some brief MVFR ceilings, although timing is a big question mark. Higher confidence exists for northern ports of FKL/DUJ where the low-level moisture pooling on the eastern slopes of the Ridges should ooze around the northern extent and invade east to west. DUJ ultimately has the best chance to see IFR overnight. Any MVFR or worse achieved tonight will be improved upon after daylight Saturday as a stout inversion is mixed out. Showers and thunderstorms could impact area airfields by Saturday afternoon/evening. Current gusts will taper off shortly after 00z areawide, but sustained flow will remain near 10kts. With strong winds found just above the aforementioned inversion, there is a low chance of llws through the pre-dawn hours, but the 10kt surface flow makes it a low enough chance to not include at this time. OUTLOOK... Brief restrictions are expected most of next week as the weather pattern remains active. No long sustained periods of IFR are predicted. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...None. OH...None. PA...None. WV...None. && $$

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