Area Forecast Discussion
Issued by NWS Pittsburgh, PA
Issued by NWS Pittsburgh, PA
557 FXUS61 KPBZ 312307 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 707 PM EDT Mon Aug 31 2026 .WHAT HAS CHANGED... With increased and persistent cloud cover in some areas, high temperatures will likely be in the low 80s while those in clearings will likely see temperatures in the upper 80s. Adjusted POPs higher Tuesday and Wednesday for possible showers and thunderstorms. Updated for the 00z TAF issuance. && .KEY MESSAGES... 1) Additional shower and thunderstorm chances at times through late week, with some possibility for severe storms. 2) Heat and humidity build through mid week && .DISCUSSION... KEY MESSAGE 1... A ridge is expected to build eastward from the Central CONUS through mid week. The highest 500mb heights are progged to be across the Lower Ohio Valley region on Wednesday. As the ridge builds eastward, shortwaves are expected to track along the northern/northeastern periphery of the ridge, crossing the lower Great Lakes/Upper Ohio Valley region. Occasional shower and thunderstorm chances are expected as these waves cross, one tonight (mainly north of the forecast area,) with another possible later Tuesday. There remains uncertainty in the placement and strength of the ridge, and the resulting track of any shortwaves on the northern periphery. There is a conditional potential for severe storms on Tuesday. ML CAPE increases to between 2000 and 3000 J/kg by late afternoon, with veering in the low levels. An initial warm layer aloft could limit convection, though a possible shortwave passage in the afternoon could trigger thunderstorms. This scenario remains uncertain due to the reasons mentioned above, though if storms are able to develop severe weather will be possible. The day with the lowest potential for showers and thunderstorms appears to be Wednesday, when the ridge is progged to be the strongest across the Ohio Valley region. Current indications are the ridge should begin to break down late Wednesday and Thursday, as a shortwave and surface cold front approaching. The potential for severe storms will also increase by Wednesday evening, increasing again on Thursday as convection increases in diurnal heating along the slow moving front. Increasing NW flow aloft should result in increased shear and diurnal instability. The potential continues for severe storms into Thursday. The latest ML guidance indicates the increasing severe potential, especially late Wednesday and Thursday. Depending on how fast the front drifts south, this potential could continue for at least southern portions of the area into Friday. Dry weather should return by the weekend as the front exits and high pressure builds in. KEY MESSAGE 2... Rising 500mb heights with the building ridge should result in warmer temperatures each day through mid week, with the heat peaking Wednesday when the ridge is strongest across the Upper Ohio Valley region. Most locations outside of the higher terrain should reach the 85 to 90 degree range on Tuesday, though there is a continued potential for convection and/or patchy cloud cover which could affect daytime highs. The heat should peak Wednesday, as highs in the upper 80s to lower 90s for most areas. The combination of heat and humidity should result in heat index values in the mid to upper 90s Tuesday and Wednesday. && .AVIATION /00Z TUESDAY THROUGH SATURDAY/... VFR with varying mid to high level bkn/ovc decks continue into the evening and overnight hours. Another round of mainly VFR showers are crossing into OH from MI. Cloud tops are already to beginning to warm in these showers as they are about 3-4 hours from our ports. There is little to spark more vigorous growth in these showers but PROB30 groups have been introduced in the 04-08z timeframe for these showers. Eventually an upgrade to TEMPO or prevailing may be in order but given a weakening trend on radar and warming cloud tops we will hold the line at lower chances for now. Progression of embedded shortwaves, that aren`t well modeled, may continue overnight into Tuesday morning and result in isolated/scattered showers and lower probability thunderstorms if/when they cross the area. Timing of these waves and the resultant coverage (or potential lack thereof) remains very difficult, preventing much mention in TAFs. Be prepared for near-term amendments adding shower/thunderstorm mentions if/when confidence in occurrence increases. At this time PROB30 groups have been maintained for many ports for the morning hours from storm activity currently across the Midwest. Outlook... During non-convective periods with no prior rain occurrence, VFR is likely under the influence of ridging to the southwest. Shortwave movement along the northern periphery of the ridge could create short periods through the week where showers/thunderstorms may occur. Due to difficulties modeling these features, timing/coverage of storm potential may be difficult until 6-12 hours before arrival and cause larger- than-normal fluctuations in TAF storm timing. Additionally, storm environments may be conducive to gusty, erratic winds plus heavy downpours that could contribute to restriction development. && .PBZ WATCHES/WARNINGS/ADVISORIES... PA...None. OH...None. WV...None. && $$ DISCUSSION...WM/Lupo AVIATION...Frazier/AK