Area Forecast Discussion
Issued by NWS Pittsburgh, PA
Issued by NWS Pittsburgh, PA
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061 FXUS61 KPBZ 050456 AAB AFDPBZ Area Forecast Discussion...UPDATED National Weather Service Pittsburgh PA 1256 AM EDT Wed Jun 5 2024 .SYNOPSIS... Widespread showers and storms return today. Unsettled weather will remain into the weekend. Cooler temperatures return Friday and hold through the weekend. && .NEAR TERM /THROUGH TODAY/... KEY MESSAGES: - Shower and storm chances increase today with the passage of an upper level wave. - Another warm day. -------------------------------------------------------------- Some minor timing differences in the PoPs late tonight. A weak shortwave trough will cross the region before dawn, increasing deep moisture and the risk for showers. Rainfall should be light as much of the wave`s energy will be used to break down the ridge. Temperatures overnight will remain mild. A series of shortwave troughs will cross the region today. The first, which will move through this morning, will flatten and push the eastern ridge over eastern PA. This wave will also thicken and lower cloud cover. Showers will overspread the region from the southwest. Seeing some differences in coverage of the activity this morning. Rainfall should be light. Latest NBM probs for measurable rainfall (>0.01 inches) generally range from 50 to 70%. Probs for >0.10 inches fall off to 20 to 30% this morning. A more significant shortwave will cross the region this afternoon with its focus on locations south and east of Pittsburgh. NBM is showing higher probs for rainfall this afternoon over the ridges. Latest CAM models are also broadcasting the more likely place for stronger afternoon convection and heavier rain east of PIT. Instability will be descent this afternoon, but strong wind shear will be lacking. What shear is available will ride up along the higher elevations ahead of the shortwave. Cloud cover and warm air aloft will be limiting factors today as well. && .SHORT TERM /TONIGHT THROUGH FRIDAY/... KEY MESSAGES: - Cold front crosses late tonight keeping in the threat for showers and storms. - Risk for scattered showers/storms continues on Thursday with the passage of a deep trough. - More activity on Friday with cooler temperatures. ------------------------------------------------------------------- A cold front will cross our area late tonight. Showers and thunderstorms are expected to develop ahead of this front in the warm sector. Modest deep-layer shear to around 30-40 kts during the evening may support isolated severe storms, with damaging wind as the primary hazard. An isolated weak tornado cannot be ruled out, though that threat will mainly remain mainly south of PIT. However, early rounds of rain and overcast conditions, along with waning instability after dark, may act to hamper this threat. The latest Day 2 Outlook from SPC includes a Marginal Risk for much of the forecast area, with a 5% wind threat and 2% tornado threat. Lingering showers/storms will end Thursday morning as the cold front exits to the east. A deep shortwave trough is expected to swing through Thursday afternoon. This will likely return showers and storms Thursday afternoon/evening. Just above-average highs expected Thursday. Highly anomalous upper level low will move across the Great Lakes on Friday. Waves of energy will swing around the low as will much cooler air. This will keep our weather unsettled on Friday. Temperatures should be noticeably cooler Friday with plenty of clouds, scattered showers and 850T of +5 to +9. Will go with NBM 10th pct for highs Friday. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... KEY MESSAGES: - Periodic showers with cooler conditions are expected through the weekend with a slowly crossing upper-level low. ------------------------------------------------------------------- The upper-low will dig into New England by Saturday. This will keep cooler and showery conditions in the forecast as we head into the weekend and into early next week. While there is low confidence on pinpointing the best timing of these showers each day, ensembles do agree on the general showery pattern with upper troughing persisting through the weekend and possibly into early next week. && .AVIATION /06Z WEDNESDAY THROUGH SUNDAY/... VFR is expected through early morning as a shortwave ridge moves east of the region. Scattered showers are expected to move across the region this morning, with increasing moisture and ascent ahead of an approaching shortwave trough and surface cold front. Local restrictions are possible in these showers, though uncertainty in location and timing of the showers precludes more than a VCSH inclusion in the TAFs. A mid level trough, ahead of the main approaching shortwave, is expected to lift across the Upper Ohio Valley region this afternoon. This should be the focus for showers, and thunderstorms, as destabilization occurs. ML CAPE is expected to be around 1000 j/kg as the initial trough crosses. Inoculated a more focused Prob30 line in the tafs for this feature. The main shortwave trough, and its associated surface cold front, is expected to cross the region late this afternoon and tonight. Additional showers and thunderstorms are expected, with higher probability of occurrence than the mid afternoon activity. Included a Tempo line for thunderstorms in the tafs to focus on this feature as it crosses. .Outlook... Periodic restrictions and scattered showers are expected Thursday through Sunday as a slow moving upper low persists across the Great Lakes region. && .PBZ WATCHES/WARNINGS/ADVISORIES... PA...None. OH...None. WV...None. && $$ SYNOPSIS...22 NEAR TERM...22 SHORT TERM...Rackley/22 LONG TERM...Rackley/22 AVIATION...WM