036 FXUS61 KPBZ 031846 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 246 PM EDT Tue Jun 3 2025 .SYNOPSIS... Dry and warmer weather is expected through Wednesday under high pressure. Showers and thunderstorm chances return Thursday with an approaching cold front. This front is expected to drift southward through Saturday, keeping unsettled weather in the forecast. && .NEAR TERM /THROUGH TONIGHT/... KEY MESSAGES: - Dry and warm with hazy conditions possible. --------------------------------------------------------------- As temperatures continue to rise today, it is expected that some Canadian wildfire smoke from aloft is mixed to the surface, as indicated by HRRR- Smoke. The 12Z sounding showed no stark inversion, so the warmer temperatures get would correlate to the more mixing of smoke concentrations. Visual cues as of 2pm already indicate some high-visibility haze, which is expected to linger over the next couple days as we advect Moderate AQIs from the US southeast. Air quality degradation, with current forecast highs, are not expected to be particularly impactful, but sensitive groups are encouraged stay tuned to the forecast for any updates. Synoptically, this will be at least day one of eastern ridging, with surface high pressure to the east. This pattern of subsidence should stave off cloud coverage, through low-level southwest flow overnight is expected to increase moisture, keeping low temperatures around 5 to 10 degrees above average. Chances of staying above 70F are 10% to 20% along the ridges and in the Ohio Valley. && .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... KEY MESSAGES: - Hot with moderate heat risk for valleys / urban areas Wed. - Storm chances in eastern Ohio Thursday. ---------------------------------------------------------------- Height rises continue into Wednesday, with heights topping out as high as 588dm to 590dm, particularly southeast of Pittsburgh. While this might allude to temperatures pushing 90F, there may be enough moisture return Wednesday morning to support a cumulus deck and some uncertainty with smoke concentrations and their potential to lower highs a degree or two from what they would have otherwise. CIPS analogs maintain around a 70% chance of temperatures topping 85F, with a <10% chance of 90F. HREF probabilities have backed off with chanced of >85F, only exceeding 50% in valley and urban areas. All in all, we would expect urban heat islands and river valley to be the warmest, where a moderate heat risk is forecast, with the hottest hours Wednesday afternoon. High clouds increase overnight ahead of the next wave, increasing insolation in southwest flow. This has the potential for lows to be 10F to 15F above normal. By Thursday, there should be enough moisture return to allow for increased convective activity, with the highest rain chances along the CAPE gradient associated with the approaching front. Frontal progression is expected to be slow, so any storms Thursday would have to fire off the front or subtle forcing, creating a domino effect of gust fronts and new updrafts, highest for eastern Ohio. There is a low chance the mountains may be in play too with ridgetop convergence. The 50th percentile CAPE has ~1000 J/kg, but shear remains low. With dry air aloft (500-600 mean DCAPE, 900 90th percentile DCAPE), this may signal a downburst wind threat with isolated flooding concerns possible. Concerns wain overnight with the loss of heating. && .LONG TERM /FRIDAY THROUGH MONDAY/... KEY MESSAGES: - Slow frontal passage this weekend with rain and storm chances. ------------------------------------------------------------------- A good deal of what each day looks like Friday through Sunday will depend on the exact timing and location of the front. Most ensemble clusters signal at this slow crossing, where the front is across the area Friday and into Saturday. Subtle differences in timing wash out the ensemble mean instability a bit, suggesting decreases each day, but more likely, the environment will be a bit similar each day, primarily governed by diurnal storms with as least a chance of downburst wind and hail threats. Any time we have a stalled boundary, flooding also remains a concern in training, especially with 1-1.5" PWATS. The exacts of this will need to continue to be more flushed out. Clustered ensembles remain in good agreement save an outlier of a slightly more progressive front, drier, and cooler conditions Sunday (11% of membership). Otherwise, there is good confidence in eastern troughing by the middle of next week with uncertainties in timing, amplitude, and just how fast we return to ridging late week. Much of the temperature spread if from the mid 70s to mid 80s for highs. && .AVIATION /18Z TUESDAY THROUGH SUNDAY/... VFR will continue through the forecast period with high pressure in control across the eastern CONUS. Canadian wildfire smoke remains elevated but visible via satellite imagery, and hi-res models do indicate an increase in smoke closer to the surface later this afternoon. There remains uncertainty into the degree of VIS impacts, but it is possible ports could see 4-6SM in HZ based on current guidance and upstream observations. Have opted to keep out of latest TAFs for now given uncertainty. Outlook... High pressure 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). The next potential impact period will be on Thursday when shower and thunderstorm chances increase (and restrictions mainly tied to convection) as a series of shortwaves cross over the ridge axis. && .PBZ WATCHES/WARNINGS/ADVISORIES... PA...None. OH...None. WV...None. && $$ SYNOPSIS...Milcarek NEAR TERM...Milcarek SHORT TERM...Milcarek LONG TERM...Milcarek AVIATION...88/AK