Area Forecast Discussion
Issued by NWS Pittsburgh, PA
Issued by NWS Pittsburgh, PA
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966 FXUS61 KPBZ 110702 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 302 AM EDT Tue Jun 11 2024 .SYNOPSIS... Cool and dry conditions continue today, followed by warming temperatures but still dry weather Wednesday and Thursday. Thunderstorm chances return Friday. Much warmer weather is possible this upcoming weekend into early next week. && .NEAR TERM /THROUGH TODAY/... KEY MESSAGES: - Cool and dry weather expected under building high pressure. -------------------------------------------------------------- The upper shortwave that brought clouds and isolated showers to the area on Monday is centered roughly over the northeastern CONUS, with cloud cover along its southwest periphery still impacting the high terrain and adjacent lowlands early this morning. Farther west where clouds have cleared, effective radiational cooling is allowing for patchy fog to form, with the greatest concentration occurring in and around river valleys. Morning fog will dissipate after sunrise and the clouds over the eastern half of the area should begin to scatter out as the upper trough continues to advance eastward off the New England coast this afternoon. In its wake, high pressure begins to build into the region, bringing drier deep-layer moisture profiles and clearing skies. Meanwhile, northwest flow will continue to support cold air advection (albeit weakening as the trough gets farther to the east). This will keep temperatures below seasonal as afternoon highs top out in the upper 60s along/north of I-80 to low/mid 70s farther south. && .SHORT TERM /TONIGHT THROUGH WEDNESDAY NIGHT/... KEY MESSAGES: - Upper ridging Wednesday maintains dry weather and returns temperatures to near or above average across the region. ------------------------------------------------------------------- Dry, quiet weather is expected tonight through Wednesday night under weak ridging building over the area. Temperatures will remain below climatological normals tonight as lows dip once again into the upper 40s north to low 50s south. A warming trend begins during the day Wednesday, but temperatures will be only slightly above normal as a passing trough well to the north along the the northern Great Lakes helps to lessen the impact of the building ridge. As such, expect highs in upper 70s to low 80s, followed by lows Wednesday night in the mid to upper 50s. && .LONG TERM /THURSDAY THROUGH MONDAY/... KEY MESSAGES: - Warm, dry conditions are expected Thursday. - Long range models are hinting that thunderstorm chances return Friday, there is a chance that a few storms could be strong to severe. - Models have been consistent that hotter conditions are favorable late week into early next week. ------------------------------------------------------------------- With a ridging building to our south and elongated trough over central Canada, zonal flow will advance warm conditions over the Midwest into the region. Confidence is high that upper-80s to near 90s will be observed across the region on Thursday. Minus the heat index values in the low-90s for portions of Ohio, no hazardous weather is expected as conditions remain dry. Trough advancement out of the north will bring a cold front through the area late Thursday night into Friday. There is some signal among global models that showers and thunderstorms develop ahead of the front Thursday night, though there is uncertainty regarding how far they make it into our area as they move into an area of weaker instability and forcing. Still, introduced low (generally 20-30%) rain chances over northwest PA and northeast OH to account for this potential. The better chance for showers and storms will occur along the cold front itself as it pushes through the area during the day Friday. Probability of organized convection (500 J/kg and 30kts of effective shear) is 20% to 40% Friday evening with this noted disturbance, meaning there is some low-end potential for a few storms to become strong or severe. Long range guidance has been consistent that a ridge axis will build across much of the central and eastern CONUS thereafter through the weekend and into the following week, bringing warm and humid conditions to the area. There is a growing concern that significant heat will be possible, especially as we get into early next week, with NBM probabilities for high temps reaching 95+ degrees on Monday continuing to run around 50% or greater. The highest probabilities for impactful heat are noted across eastern OH and the valleys and low elevations of western PA, including urban centers like Pittsburgh where the heat island effect typically leads to locally warmer temperatures compared to surrounding areas. If this trend in guidance continues, heat impacts will need to be closely monitored and headlines may need to be considered. && .AVIATION /06Z TUESDAY THROUGH SATURDAY/... MVFR cloud deck is continuing to scatter into western Pennsylvania overnight and bringing an end to CIG restrictions. Clouds will linger longest north and east (FKL/DUJ/LBE) of PIT. Given the building cool air mass, diminishing wind, and relatively warm rivers, some patches of mainly valley-based fog are possible and already appearing on satellite in areas that have seen cloud cover dissipate. Latest hi res ensemble probabilities favor a 50-60% chance of restrictions to MVFR VIS for FKL and ZZV in the pre-dawn hours. Elsewhere where cloud cover lingers, fog development shouldn`t be impactful. Any fog should lift by 13z Tuesday morning, though probability of MVFR CIGs at FKL/DUJ don`t indicate improvement until after 15-16z when flow backs to the west and cuts off the lake moisture source. Scattered cumulus is expected during the late morning/midday hours elsewhere. Northwest wind will generally remain light at under 10 knots. .Outlook... VFR conditions are expected under building high pressure Tuesday through Thursday. Restrictions in showers and thunderstorms return Thursday night and Friday with another passing disturbance. && .PBZ WATCHES/WARNINGS/ADVISORIES... PA...None. OH...None. WV...None. && $$ SYNOPSIS...Cermak NEAR TERM...Cermak SHORT TERM...Cermak LONG TERM...Cermak AVIATION...Rackley/MLB