Area Forecast Discussion
Issued by NWS Pittsburgh, PA
Issued by NWS Pittsburgh, PA
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953 FXUS61 KPBZ 241046 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 646 AM EDT Mon Jun 24 2024 .SYNOPSIS... Dry and cooler weather is expected today under building high pressure. Mainly dry and warmer weather is expected Tuesday, before showers and thunderstorm chances return Tuesday night and Wednesday with the approach and passage of a cold front. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... KEY MESSAGES: - Seasonable temperatures and less humid today ------------------------------------------------------------------- Surface high pressure will build across the Upper Ohio Valley region today, as an upper trough crosses the NE CONUS. This will result in dry and seasonable weather across the region. North to northwest flow will advect drier air into the area through the day, with dew points dropping into the 50s for many locations. The CU rule and model soundings indicate a scattered cumulus cloud layer will develop as convective temperatures are reached. && .SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY NIGHT/... KEY MESSAGES: - Dry weather continues through Tuesday - Shower and thunderstorms return Tuesday night through Wednesday evening - Severe storms possible Wednesday ------------------------------------------------------------------- High pressure will slide east of the region late tonight and Tuesday, with the surface flow veering to the south. Rising 1000-500mb heights in flat ridging, and warm advection, will drive temperatures back above average by around 5 degrees. Differences exists in the operational models concerning the development of an MCS upstream on Tuesday, and its eventual track. Would expect initial development of an MCS along the 850mb low level jet late Monday night into early Tuesday across the Midwest/Western Great Lakes region. Given the tendency for MCSs to follow the 1000-500mb thickness pattern, and the best instability remaining to our west, would expect the MCS to drop southward across areas to the west of our forecast area, similar to the scenario depicted in the 00Z NSSL WRF model output. Maintained a dry forecast across the area on Tuesday at this time. Shower and thunderstorm chances will increase Tuesday night as the next shortwave trough approaches, and ascent increase in warm, moist advection. The shortwave, and its associated surface cold front, will cross the area Wednesday into Wednesday evening, with showers and thunderstorms expected. 0-6km shear is expected to increase to near 40kt, according to the latest model guidance. Model ensembles also indicate instability increasing through the day with ML CAPE around 1000 j/kg. Plenty of uncertainty still exists in the exact details of the mesoscale environment, though some severe storms could be possible should model progs verify. The Storm Prediction Center has placed a portion of SW PA and nrn WV in a Slight Risk for severe storms Wednesday, with the remainder of the area currently in a Marginal Risk. Showers and thunderstorms will end from W-E with FROPA Wednesday night. && .LONG TERM /THURSDAY THROUGH SUNDAY/... KEY MESSAGES: - Dry weather through Friday - Cooler Thursday, before a late week warmup - Shower and thunderstorm chances return for the weekend ------------------------------------------------------------------- Model ensembles indicate high pressure will build across the region Thursday. Northwest flow should result in cooler and less humid conditions. Ridging with rising 1000-500mb heights, and warm advection, will result in dry weather and above average temperatures on Friday. The next shortwave trough and surface cold front is expected to approach the region late Friday night and Saturday, returning shower and thunderstorm chances to the forecast. These should continue Saturday night into Sunday, as the front slowly crosses the region. Warm advection should result in above average temperatures on Saturday, before reading return close to seasonable levels Sunday as the cold front crosses. && .AVIATION /12Z MONDAY THROUGH FRIDAY/... Building high pressure will support VFR conditions and diminishing cloud coverage today. Forecast soundings show the boundary layer deepening by mid- morning which will yield breezy northwesterly winds as stronger winds aloft mix down. Ensembles show probabilities of >25kts around 30% at KDUJ by late morning with lesser speeds winds as you move farther south and west. .Outlook... Ensembles hint at potential MCS moving SE out of the Great Lakes sometime between Tuesday night through Thursday morning ahead of the next upper level shortwave. This is will need to be monitored for terminal impacts. Thereafter, high pressure and ridging aloft should support multiple days of dry weather. && .PBZ WATCHES/WARNINGS/ADVISORIES... PA...None. OH...None. WV...None. && $$ SYNOPSIS...WM NEAR TERM...WM SHORT TERM...WM LONG TERM...WM AVIATION...Frazier/88