Area Forecast Discussion
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000 FXUS61 KPBZ 251439 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 1039 AM EDT MON JUL 25 2016 .SYNOPSIS... A slow moving cold front will pass through the area this evening bringing the chance for scattered storms. A dry mid week before the weather pattern gets active Friday and Saturday. Above normal temperatures are forecast all week. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Updated forecast to add a heat advisory for parts of southeastern eastern Ohio and the northern West Virginia Panhandle. Heat index values are already in the upper 90s with several more hours of heating and little mixing to bring down dewpoints. Previous discussion... The area is in a lull this morning with showers and thunderstorms for now. The cold front out in Indiana will move east today and be the focus for precipitation development. Latest hi-res models do not indicate much in the way activity for our region. It appears the thunderstorm complex over western NY will kick out an outflow boundary and storms should develop southeast and move through central PA. There is the possibility that our far northeastern sections could see a storm that may approach severe limits. Much the case on Sunday, wet microbursts and heavy rain will be the primary impacts. Modified skew-ts illustrate a water loaded sounding /pwats near two inches/ yielding potential for wet microbursts. As for flash flooding, storm motion is 20-30 kts so unless training develops do not foresee a widespread event. Previous discussion below... This would mean today`s convection will be very efficient rain makers, allowing for a high risk for heavy downpours. Depending on how much sunshine, and in turn surface heating occurs today, its possible that some storms could approach severe levels. The main threat would be strong winds. Models are showing different stories on when and where convection may erupt, as they are attempting to decipher the effects of the western complex and where its energy will eventually travel. Since questions remain on location and timing, have left pops in the chance category. Temps were constructed using the Bias-Corrected short range consensus. && .SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/... Front will fizzle out tonight and do little to eject the humid airmass in place. Models are in pretty good agreement that any convection will die out tonight. Noticeably drier air does move in from the north in the mid and upper levels, however humidity levels look to remain rather high through Tuesday with the lack of low level dry advection. It will take until Tuesday night and then finally into Wednesday, when the juicy low level air is shoved to the south. Both Tuesday and Wednesday look dry with a good deal of sunshine. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... Highlights: - Continued above normal temperatures - Best shot at rain arrives Thursday night into Friday Overall no real change to synoptic pattern for much of the week as a broad H5 anticyclone dominates the southern 2/3rds of the CONUS. Our mid level height values will fall a few decameters, but not enough to usher in temps where they should be for this time of year. Based on H8 temps progs...do not see a stretch of 90F+ weather like this weekend. However, would not be surprised for eastern Ohio to be right around 90F for daytime highs most of the week. Baroclinic zone that crosses Monday night weakens and washes out over the central Appalachians Tuesday as flow become parallel to the boundary and it encounters increased subsidence. In its wake, slightly cooler weather than what we have experienced takes hold for mid week. By weeks end, another shortwave trough traverses the region sweeping a cold front through. Timing differences reside with ECMWF and GEFS, but ECMWF keeps the recent summer trend going of shortwaves passing outside peak heating hours. GFS opts for a Friday afternoon passage. Either way, the next shot of widespread precipitation appears to be Thursday night into Friday. Zonal flow re-establishes for the weekend with temperatures near the climo average of lower to mid 80s. && .AVIATION /15Z MONDAY THROUGH FRIDAY/... General VFR expected today in the warm, moist airmass ahead of an approaching front. A few showers have popped up across the region this morning, but they have missed the terminals to this point. Expect coverage to increase as we become more unstable this afternoon but with no definite line of showers and storms developing, have opted to carry VCTS in the TAFs. Restrictions will be limited to any terminal that experiences a thunderstorm. The rather diffuse front will slowly sag across the region through this evening, with a wind shift from southwest to west. .OUTLOOK /MONDAY NIGHT THROUGH FRIDAY/... Lingering low level moisture tonight may promote restrictions in fog. But after Tuesday morning, the next chance for restrictions will be with a late week front. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...None. OH...Heat Advisory until 6 PM EDT this evening FOR OHZ039-048-049- 057>059-068-069. PA...None. WV...Heat Advisory until 6 PM EDT this evening FOR WVZ003-004-012. && $$

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