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Area Forecast Discussion
Issued by NWS Pittsburgh, PA
Issued by NWS Pittsburgh, PA
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104 FXUS61 KPBZ 221602 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 1202 PM EDT Sat Jun 22 2024 .SYNOPSIS... Dangerous heat continues today with severe weather possible tomorrow afternoon; the primary threat remains wind, although hail and tornadoes are possible. A brief "cool down" is expected through Monday before temperatures increase yet again. && .NEAR TERM /THROUGH TONIGHT/... KEY MESSAGES: - Excessive Heat Warning and Heat Advisory remain in effect until 9pm. ------------------------------------------------------------------- Temperatures have already risen into the upper 80s and lower 90s area-wide as we mix up to roughly 700mb, as indicated by the morning sounding. Temperature rises through this afternoon will remain a bit slower to rise as the boundary layer continually erodes into the 700mb cap. Cumulus has started to form across the area as we tap into the LCL, but thus far development seems shallow under the initial cap. With mixing, it is expected that these cumulus grow in vertical extent, but development will be challenged past around 12kft with yet another elevated inversion. It will take repeated updraft failures to cool the environment enough to mix into the 500mb-400mb layer, but even then, storms are expected to encounter yet another inversion at 25kft. This will make it difficult for mature updrafts to materialize, especially when combined with notable dry air above the boundary layer. The main area to watch, if any, will be the lake-shore. Much like we have seen this week, we will rely on the lake boundary to initiate convection which may alter the environment enough to establish a cold pool and propagate southeast. Into this evening and tonight, a pressure gradient will increase a a Great Lakes low moves in. This will usher in light southwest flow at the surface and finally begin to usher in a different airmass. With the return of clouds tonight and light winds, tonight may be the warmest night of the week with lows only bottoming out in the low to mid 70s. This will keep conditions uncomfortable for one final night. Some nocturnal showers/storms may develop, primarily across northwest PA, with increases in 700mb moisture and fumes of CAPE, although a shallow inversion and little vertical development should keep any concerns low. && .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... KEY MESSAGES: - Crossing cold front brings showers and thunderstorms Sunday - Severe storms possible Sunday - Return to seasonable temperatures on Monday ------------------------------------------------------------------- Very warm temperatures will continue tonight as cloud cover and southwest wind increase tonight ahead of an approaching cold front. A shortwave trough, and the associated cold front, is expected to approach the region Sunday. Most available model output indicates a pre-frontal trough will cross the region from mid morning through early afternoon, with the cold front crossing through the late afternoon/evening. Increasing instability and shear is progged through the day, with ensemble based mean MU CAPE 1500-2000 j/kg by Sunday afternoon/evening, with the max surface based CAPE 2000-3000 j/kg. 0-6km bulk shear values also increase to 35-40kt, with dry mid level air enhancing downdraft CAPE. A low level jet from 35-40kt at 850mb will also enhance the damaging wind potential. Curved hodographs in the lower levels also indicate some rotation/isolated tornado potential. The Storm Prediction Center has placed much of western PA in a Slight Risk for severe storms. The main hazard is expected to be damaging wind, though with the curved hodographs and shear isolated tornadoes are also possible. The Slight Risk area is surrounded by a Marginal Risk, where FROPA timing and shear profiles are slightly less favorable for severe storms. The cold front will complete its passage Sunday evening, with showers and thunderstorms ending from W-E. Surface high pressure is expected to build under a crossing upper trough on Monday. This should return mainly dry, and more seasonable weather to the region. && .LONG TERM /TUESDAY THROUGH FRIDAY/... KEY MESSAGES: -Above average temperatures return -Mainly dry to start and end the work week, with shower and thunderstorms for mid week ------------------------------------------------------------------- An upper ridge, ahead of an approaching Midwest trough, will maintain dry weather on Tuesday. Rising 1000-500mb heights and warm advection will drive temperatures from 5 to 10 degrees above average. The trough, and its associated surface cold front, will approach and cross the region late Tuesday night through Wednesday evening, with shower and thunderstorm chances returning. Building high pressure will return dry weather for Friday, with temperatures closer to average. && .AVIATION /16Z SATURDAY THROUGH WEDNESDAY/... High probability for VFR to persist through the TAF period under the influence of high pressure. Warm, dry air aloft should limit convective initiation and keep probabilities very low of terminal impact with an afternoon thunderstorm. Approach of an upper level shortwave and associated cold front will increase thunderstorm chances at the end to after the TAF period. Latest analysis suggests to waves of thunderstorms, 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. .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. && .CLIMATE... The area has the potential to break various heat-related records. There is low probability that climate sites approach the highest temperatures recorded in the 21st century: Pittsburgh, PA: 98F (7/7/2012) Wheeling, WV: 98F (7/7/2012) Morgantown, WV: 101F (7/7/2012) New Philadelphia, OH: 101F (7/7/2012) Zanesville, OH: 101F (7/7/2012) DuBois, PA: 101F (7/22/2011) There is a low probability many June all-time temperature records may be at stake: PIT: 98F (1988) HLG: 100F (1933) MGW: 99F (1893) PHD: 99F (1988) ZZV: 101F (1988,1934) DUJ: 92F (1969) *RECORD TIED ON 6/18/24* Daily high maximum (left) and high minimum (right) temperature records are at stake for: Saturday, June 22nd Pittsburgh, PA: 98F (1988) 75F (1988) Wheeling, WV: 95F (1923) 72F (2011) Morgantown, WV: 96F (1923,1988)73F (1988) New Philadelphia, OH: 97F (1988) 71F (1997) Zanesville, OH: 99F (1988) 71F (1997) DuBois, PA: 91F (2022) 68F (2022) && .PBZ WATCHES/WARNINGS/ADVISORIES... PA...Heat Advisory until 8 PM EDT this evening for PAZ007>009-013- 015-016-022-031-074-076>078. Excessive Heat Warning until 8 PM EDT this evening for PAZ014- 020-021-029-073-075. OH...Heat Advisory until 8 PM EDT this evening for OHZ039>041- 048>050-057>059-068-069. WV...Heat Advisory until 8 PM EDT this evening for WVZ001>004-012- 021-509>511. && $$ SYNOPSIS...Milcarek NEAR TERM...Milcarek SHORT TERM...WM LONG TERM...WM AVIATION...Frazier CLIMATE...