971 FXUS61 KPBZ 020653 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 253 AM EDT Mon Jun 2 2025 .SYNOPSIS... Rising temperature is likely through Wednesday along while being precipitation free. Lofted wildfire smoke may hamper the degree of heating while potentially reaching the lower levels Tuesday. Shower and thunderstorm chances are likely to return late in the week. && .NEAR TERM /THROUGH TONIGHT/... KEY MESSAGES: - Patchy frost this morning for portions of NW PA and the WV higher terrain. - Dry weather persists but lofted wildfire smoke may limit total heating ------------------------------------------------------------------- Strong radiational cooling with mostly clear skies and light wind may allow for frost development in portions of northwest PA and the WV high terrain, where a Frost Advisory remains. Conditions will improve shortly after sunrise as the surface heats. The Upper Ohio River Valley will continue to see height rises aloft as the New England trough slinks farther east and ridging nears from the Central Plains. High pressure at the surface will help ensure dry weather with abundant sunshine (see disclaimer below) as areal high temperature trends another 5 to 8 degrees warmer than Sunday. Overnight low temperature will see similar rises despite potential for another strong radiational cooling night. Disclaimer: outside of a few afternoon cumulus, skies are highly likely to be free of clouds. HOWEVER, as was seen Sunday, the upper level pattern will continue feeding Canadian wildfire smoke overhead as HRRR modeling suggests its thickness being similar to Sunday but spreading over the entire region. Looking at climate site readings, this layer seemed to cool daytime highs ~2 degrees from model mean values; a similar reduction in ensemble model means was applied to the high temperature forecast for today. There is some insinuation that smoking mixing to the surface cold occur late in the day in northwest PA (leading to more surface-based haze), but it appears too localized for forecast mention. Overnight low temperature into Tuesday morning may be more mild as well (forecast trends this way) as thicker elevated smoke limits the degree of radiational cooling. && .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... KEY MESSAGES: - Rising temperature continues with ensembles favoring Wednesday for its peak. - Impacts of wildfire smoke may increase Tuesday into Wednesday. ---------------------------------------------------------------- There is high confidence in notable upper level ridging to shift overhead Tuesday and position over the Atlantic Coast Wednesday. These height rises (Tuesday) and increasingly warm/moist southwesterly flow (Wednesday) will continue the region`s trend of rising temperature while keeping the area precipitation free. Ensembles suggest high temperature is likely to peak Wednesday, with 60-90% probabilities for valleys and urban areas from Pittsburgh west seeing maximum temperature hitting/exceeding 90 degrees. If this occurs, heat risks will rise and would warrant properly planning to mitigate its impacts if you have outdoor plans. Like the prior section, the impacts of wildfire smoke could dampen the degree of rising temperature and cause many areas to fall short of 90 despite those high probabilities. HRRR modeling suggests that far eastern OH through western PA could see smoke mixing down to the surface by Tuesday afternoon; similar model outputs of this variable yielded generally 4 to 6 mile visibilities across Minnesota/Iowa Sunday afternoon. Given that verification, the forecast now includes the mention of haze due to the likely presence of wildfire smoke Tuesday afternoon. This could continue into Wednesday, but the lack of smoke modeling out that far limits confidence to add it into the forecast. Visit airnow.gov or your states department of environmental services to better understand the potential impacts of wildfire smoke levels. Shortwave movement over the western Great Lake may nudge showers and thunderstorms far enough east Wednesday night to reach the far northwest forecast zones. However, the more likely scenario is increased cloud coverage before chances rise Thursday. && .LONG TERM /THURSDAY THROUGH SUNDAY/... KEY MESSAGES: - Shower and thunderstorm chances increase heading into the weekend - Any hazardous weather may be predicated on upstream convective evolution ------------------------------------------------------------------- Ensemble models favor the movement of multiple shortwaves over the top of the southeast CONUS ridge Thursday through Saturday that will slowly shunt it move over the Gulf States. Each wave is likely to promote showers and thunderstorms but timing and storm evolution variances remain large and somewhat predicated on upstream convective evolution. The general expectation would be to see periods of showers/thunderstorms with chances peaking around Saturday with a potential trough axis crossing while temperature trends toward seasonal averages. The lack of strong flow during this period and complications of upstream convection make analysis of hazardous weather potential difficult. That said, the broad setup of a ridge breakdown can be a precursor to severe weather and bares monitoring as the period of note approaches. && .AVIATION /06Z MONDAY THROUGH FRIDAY/... VFR conditions are forecast through the TAF period. Some patchy valley fog is possible once again tonight but it is generally not expected to impact terminal forecast locations. Wind remains light and generally westerly. Models indicate lower wildfire smoke concentrations today, but point to quick increases in vertically integrated smoke after 00z Tuesday. Initially, this is not expected to impact surface visibility, but HRRR-Smoke shows increasing near-surface smoke density by 12z Tuesday. Outlook... High pressure and ridge building near the region is very likely to maintain general VFR through Wednesday, with surface wind generally light until Wednesday afternoon (breezy SW wind as the surface high shifts). Near-surface wildfire smoke densities are likely to increase on Tuesday with impacts to surface visibility. Estimates are generally a 4-6SM haze with thicker smoke. The next potential impact period will be late week when shower and thunderstorm chances increases (and restrictions mainly tied to convection) as a series of shortwaves cross over the ridge axis. && .PBZ WATCHES/WARNINGS/ADVISORIES... PA...Frost Advisory until 8 AM EDT this morning for PAZ009-015-016. OH...None. WV...Frost Advisory until 8 AM EDT this morning for WVZ514. && $$ SYNOPSIS...Frazier NEAR TERM...Frazier SHORT TERM...Frazier LONG TERM...Frazier AVIATION...Rackley