Area Forecast Discussion
Issued by NWS Pittsburgh, PA
Issued by NWS Pittsburgh, PA
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931 FXUS61 KPBZ 230719 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 319 AM EDT Sun Jun 23 2024 .SYNOPSIS... Showers and thunderstorms are expected at times today with the approach and passage of a cold front. Some of the storms could be severe this afternoon and evening, with damaging wind the main hazard. Generally dry weather and more seasonable temperatures are expected Monday and Tuesday as high pressure builds in. && .NEAR TERM /THROUGH TONIGHT/... KEY MESSAGES: - Showers and thunderstorms return at times today with a crossing cold front - Severe storms are possible this afternoon and evening - Cooler temperatures tonight ------------------------------------------------------------------- Early morning temperatures remain warm this morning. These readings could break the record warm lows for the day, if not for temperatures falling before midnight tonight after the passage of a cold front. A shortwave, and its associated surface cold front, will approach the region today. A prefrontal trough, associated with convection across the Midwest, will track across the Upper Ohio Valley region later this morning and early afternoon. While a weakening trend is expected in this convection, showers and thunderstorm chances will escalate as the trough approaches. A low level will also support this activity as it tracks across the region. The storms are expected to increase in strength again this afternoon as diurnal instability builds. In addition, the surface cold front is expected to cross the region from W-E from early afternoon through early evening. Additional thunderstorm development is expected along, and ahead of the front. Ensemble based MU CAPE is progged between 1500 and 2000 j/kg this afternoon, with some operational CAMS and ensemble max values around 2500 j/kg. 0-6km shear is also expected to increase to 35-40kt at the same time. A relatively strong wind field aloft, along with mid level dry air, should result in a damaging wind potential for storms with organized updrafts. CAMS output shows DCAPE levels 1000-1200 j/kg this afternoon/evening ahead of the front. A veering wind profile/curved hodographs indicate a tornado potential as well, especially with discrete cells. The Storm Prediction Center has placed the forecast area in a Slight Risk for severe storms today. The main hazard is expected to be damaging wind gusts, though with the veering wind profile isolated tornadoes are also possible. The hail potential remains limited. Uncertainty remains in how the prefrontal trough will affect destabilization ahead of the front, and how strong storms will become along the trough in the afternoon. There is also uncertainty in how much the dry air aloft will affect updraft strength. The front will complete its passage this evening, with shower and thunderstorms exiting the region. Generally dry and cooler weather is then expected overnight as surface high pressure begins to build under a crossing trough aloft. High temperatures will be cooler today, though still around 5-8 degrees above average. Lows tonight should drop into the lower 60s for most locations, with upper 50s in some outlying areas. && .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... KEY MESSAGES: - Mainly dry weather returns - Seasonable temperatures return Monday, warmer Tuesday ------------------------------------------------------------------- The upper trough will cross the NE CONUS Monday, as surface high pressure builds in underneath. This should result in dry and seasonable weather. Mainly clear skies and light wind should result in radiational cooling Monday night. Most locations will see lows in the 50s. Patchy river valley fog is also expected. Rising 1000-500mb heights and warm advection should return temperatures to above seasonable levels on Tuesday. A couple of MCSs are expected to develop across the Midwest region Tuesday night. Some operational models brush these complexes near the Upper Ohio Valley region late Tuesday and Tuesday night. Given the placement of the low level jet upstream, and the tendency for MCSs to follow the 1000-500mb thickness pattern, think these will stay to our west at this time. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... KEY MESSAGES: - Thunderstorms likely with a Wednesday cold front - Cooler Thursday, followed by a warming trend - Dry Thursday and Friday, before another front approaches Saturday ------------------------------------------------------------------- The next shortwave trough, and associated surface cold front, is expected to approach and cross the region on Wednesday, with showers and thunderstorms likely. Strong to severe storms will be possible, if current model projections of shear and instability levels verify. High pressure is expected to return dry weather to the region Thursday and Friday. Seasonable temperatures are expected Thursday, before a return to above average readings on Friday as heights rise and warm advection occurs. The next approaching cold front will return shower and thunderstorm chances back to the forecast at the start of the weekend. && .AVIATION /07Z SUNDAY THROUGH THURSDAY/... High probability for VFR to persist through tonight and much of the day Sunday. Approach of an upper level shortwave and associated cold front will increase shower and thunderstorm chances after 15Z and lasting through the end of the TAF period. Latest analysis suggests two primary waves, the first between 15-20z (11am-4pm EDT) along a pre-frontal trough, and the second between 21z-03z (5pm-11pm EDT) as the cold front advances southeast. Storm intensity (and probability of terminal impact) is likely to be highest with the second wave. Could see restrictions to cigs/vis in and around heavier storms. Some storms may be strong to severe, particularly with the second wave. Damaging winds, hail, and tornadoes are all possible. .Outlook... Lingering showers and low probability thunderstorms are possible through early Monday morning amid cold advection and crossing of the upper trough axis. High pressure and northerly flow aloft will establish dry and more seasonable conditions for the start of the next work week. && .PBZ WATCHES/WARNINGS/ADVISORIES... PA...None. OH...None. WV...None. && $$ SYNOPSIS...WM NEAR TERM...WM SHORT TERM...WM LONG TERM...WM AVIATION...Cermak/Frazier