Area Forecast Discussion
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380 FXUS61 KPBZ 190123 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 923 PM EDT Fri May 18 2018 .SYNOPSIS... The unsettled weather pattern persists into next week as a series of low pressure cross the region. Temperatures will continue to be above normal as well the frequency of grass cutting. && .NEAR TERM /THROUGH SATURDAY/... Evening Update: The flood watch for Tucker and Garrett County have been cancelled, rain will still be move through overnight...but there is a low chance for excessive rain. Previous Discussion: As flow veers around to the south look for measurable QPF to spread across a good chunk of the area. The time window for the rain will be between 4z-9z. Given all the rain, left the flood watch up there and ran it through the period of heaviest rainfall /6Z/. It would not be surprising to see the watch be cancelled early. Mudslides are another primary impact there outside of high water. A break in the action much of Saturday morning for the region as a mid level dry slot moves overhead. This drops the amount of total moisture in the column evident by PWATS falling back to 1.2". This will be short lived as the next mid level trough approaches from the west. This will cross during the late afternoon and evening hours. Depending how much sunshine we get, there is a small chance of strong storms. H7-H5 lapse rates are not nearly as steep as previous days with values around 6ckm-1. There is still modest unidirectional wind shear which could sustain storms as they move east from central Ohio. Storms will be moving so a high water threat is not foreseen. Full sunshine is not expected tomorrow so we won`t be able to realize all of the mixing from H8. However it will be a little warmer as values climb close to 80F for the lower elevations. && .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 /01Z 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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