Area Forecast Discussion
Issued by NWS Pittsburgh, PA
Issued by NWS Pittsburgh, PA
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695 FXUS61 KPBZ 010754 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 354 AM EDT Mon Jul 1 2024 .SYNOPSIS... High pressure will provide dry and comfortable weather for the first half of the week before an unsettled pattern takes hold to close out the week. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... KEY MESSAGES: - Dry and comfortable today. - Temperatures below normal. ------------------------------------------------------------------- Slow height rises aloft and building high pressure will provide dry and comfortable conditions with lots of sunshine. With a cool northwest flow aloft, temperatures will be below normal. && .SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/... KEY MESSAGES: - Dry weather through Tuesday and most of Wednesday. - Temperatures warm both days with above normal readings returning on Wednesday. ------------------------------------------------------------------- Building 500mb ridge is anticipated on Tuesday as well as warm air advection. Surface high pressure will drift across the region. All of this will mean another quiet weather day with temperatures warming to near or just above normal. Ridge will slowly break down on Wednesday, as a shortwave trough digs into the upper Midwest and pulls a surface cold front eastward. Even though the ridge will be flattening, warm air advection is expected to continue pushing highs toward 90 degrees. Still some timing issues on how quickly activity may reach the western half of the region ahead of the cold front. NBM begins to introduce probabilities for measurable precipitation Wednesday afternoon. The high probs (30-40%) are mainly over Ohio and NW PA. Current rainfall amounts Wednesday afternoon look light on the NBM, however this activity will be convective in nature, so it will be helpful to get a look at the CAM models as Wednesday gets closer. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... KEY MESSAGES: - Showers and thunderstorms possible Wednesday night continuing through the end of the work week with the return of a more active pattern. ------------------------------------------------------------------- Ensembles break the ridge down and shunt it southward over the Southeast CONUS and Gulf Coast, leaving zonal flow over the Ohio Valley and lower Great Lakes while lower heights settle in upstream over the upper Great Lakes and Midwest. This patten is certainly more active than the first half of the week, promoting surface low pressure over southern Ontario that quickly tracks northeastward and leaves a trailing cold front sagging southward into our area Wednesday night into Thursday. There is some minor concern at this time that the zonal flow overtop what appears to be a slowing and weakening/diffusing cold front could lead to a setup where multiple rounds of showers and storms develop along said east-west oriented boundary in a moisture- rich environment (ensemble mean PWATs surpassing 1.75 inches), leading to training of thunderstorms and flooding rain potential. Still a bit too far out to dive into certain specifics, but will have to keep an eye on the pattern evolution and potential for an unsettled July 4th holiday. Machine learning continues to highlight some severe potential with this pattern as well as the front will initially be moving into a warm and moist airmass, though weak flow aloft resulting in limited bulk shear is helping to keep the overall threat low at this time. Still, this too will bare watching over coming days. Ensembles then signal an upper wave diving through the Great Lakes to close out the week, though uncertainty comes into play with how deep the trough is and subsequently how strong the surface low is and where it tracks. Consensus is to our north and dragging a cold front through sometime early in the weekend, but details remain fuzzy. && .AVIATION /08Z MONDAY THROUGH FRIDAY/... A low VFR / high MVFR stratocumulus deck continues to be observed at TAF sites and via visible satellite for select PA/WV ports. This will continue to erode and lift slightly overnight in subsidence, with the most uncertainty in MVFR maintenance progged for FKL/DUJ with continued lake influence in NNW flow. Low-level, dry air will mix into the boundary layer, come daytime, clearing skies before high clouds arrive in the evening and overnight. .Outlook... VFR is expected until a slow moving front sets up across the region Wed and Thu. && .PBZ WATCHES/WARNINGS/ADVISORIES... PA...None. OH...None. WV...None. && $$ SYNOPSIS...22 NEAR TERM...22 SHORT TERM...22 LONG TERM...Cermak/MLB AVIATION...Milcarek