Area Forecast Discussion
Issued by NWS Pittsburgh, PA
Issued by NWS Pittsburgh, PA
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811 FXUS61 KPBZ 250454 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 1254 AM EDT Tue Jun 25 2024 .SYNOPSIS... Dry and cooler weather is expected tonight under high pressure. Showers and thunderstorms are possible Tuesday and especially Wednesday as a slow moving front pushes into the Ohio Valley. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... KEY MESSAGES: - Quiet with light winds under high pressure tonight. ------------------------------------------------------------------- Evening Update... Little change needed to the forecast this evening as everything remains on track. See the previous discussion below for more details. Previous Discussion... 500 mb heights have been rising about 70 meters today and should rise another 40 meters tonight. High pressure centered along the OH/IN border currently will head across OH this evening and into PA after midnight. Cumulus will rapidly dissipate by early evening with clear skies. Tds are in the 50s, so lows in the 50s appear reasonable. Fog development is likely in many of the river valleys but not expected to be unusually impactful. && .SHORT TERM /6 AM THIS MORNING THROUGH WEDNESDAY NIGHT/... KEY MESSAGES: - Shower and thunderstorms chances return especially by Wednesday when severe storms are possible. ------------------------------------------------------------------- WNW flow at 500 mb with heights in the lower 5800s is expected with somewhat warmer temperatures and gradually rising Tds on Tuesday. Have low confidence in thunderstorm chances as there is poor agreement in the CAMS on how convection in MN area this afternoon and tonight evolves. FV3 is northern outlier bringing MCS across MI and eventually across Lake Erie into NE OH/NW PA Tuesday afternoon. Other options range from a weakening system falling apart to having everything sway well west as large cold pool turns convection southward and cuts off moisture west of Ohio. So will be at the mercy of convective scale cold pool development and movement so details will be scarce except in the 6-12 hour range. Trough pushes across Ohio River Valley with 60 meter height falls expected Wednesday over the forecast area. 25th to 75th percentile QPF for KPIT ranges from 0.25" to 1.00", and with convection there will always be a rather large range so this seams reasonable. And as noted for Tuesday, the Wednesday convective setup will be modulated by the evolution of Tuesdays convective cold pools. && .LONG TERM /THURSDAY THROUGH MONDAY/... KEY MESSAGES: - Dry weather Thursday through Friday - Near normal temperatures Thursday, before a late week warmup - Shower and thunderstorm chances return for the weekend ------------------------------------------------------------------- Cold front pushes through Wednesday night with significant cooling and drying at low levels across the Upper Ohio River Valley on Thursday. So near normal temperatures and quiet weather are expected. Heights gradually rise about 60 meters each day Thursday through Saturday, eventually reaching about 5920 meters by Saturday. 850 mb temps will be 12C Thursday, rising to about 18C Friday and near 20C on Saturday. So a warming trend is expected and will culminate in decent shot at showers and thunderstorms with a cold pushing through by Saturday night. Currently 30-50% chance of hitting at least 90F by Saturday over the forecast area, with highest values in the central and southern zones. 50-75th percentile QPF at KPIT is roughly 0.25 to 0.65" for Saturday. Trough pushes by Sunday with ridge building in Monday. Odds favor dry weather and near to slightly above normal temperatures. At this point ensembles suggest an upper high centered over lower MS river valley with hottest temperatures well southwest of the forecast area. && .AVIATION /06Z TUESDAY THROUGH SATURDAY/... VFR is expected through much of the TAF period, outside of some early morning MVFR to IFR river valley fog. A mesoscale convective system (MCS) was developing across the Western Great Lakes region. This is initially expected to track eastward overnight, before diving to the south following the 1000-500mb thickness pattern and theta e gradient. It appears most of the thunderstorm activity should stay just west of the area where the best instability is expected, though an increase in mid and dense high level clouds is expected. There is some potential the MCS could track further east and reach some Ohio airports, though a rapid weakening in thunderstorms is expected by that time. A few SW wind gusts up to 20 mph are expected today with mixing. Shower and thunderstorm chances increase late tonight with the approach of the next shortwave trough and surface cold front. For now, included a VCSH at the end of the PIT TAF with uncertainty in how much precip development will occur overnight. .Outlook... Restrictions are expected Wednesday with ocnl showers and thunderstorms as a cold front crosses the region. VFR returns Thursday and Friday under high pressure. Restriction, and shower/thunderstorm potential returns Saturday with the approach of a cold front. && .PBZ WATCHES/WARNINGS/ADVISORIES... PA...None. OH...None. WV...None. && $$ SYNOPSIS...Craven NEAR TERM...Craven SHORT TERM...Craven LONG TERM...Craven AVIATION...WM