Area Forecast Discussion
Issued by NWS Pittsburgh, PA
Issued by NWS Pittsburgh, PA
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131 FXUS61 KPBZ 302131 AAA AFDPBZ Area Forecast Discussion...UPDATED National Weather Service Pittsburgh PA 531 PM EDT Sun Jun 30 2024 .SYNOPSIS... Building high pressure will return comfortable dry weather for the first half of the week before an unsettled pattern takes hold to close out the week. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... KEY MESSAGES: - Cooler and drier weather expected tonight behind an exiting cold front ------------------------------------------------------------------- Update... The latest mesoanalysis shows a cold front extending from eastern PA through northern WV. An isolated shower or thunderstorm is possible as the front clears Tucker county WV, though dry air was precluding any significant convective development. Previous discussion... We then finally get a push of drier air (dew points in the 40s upstream) as high pressure builds across the Great Lakes and reinforces northerly flow in the wake of the boundary. Clouds will scatter into early this evening save for north of I-80 where forecast soundings indicate that lake moisture under northerly flow will remain trapped beneath increasing subsidence. In addition, a passing upper wave looks to reinforce cloud coverage further south toward morning on Monday. Still, overnight lows will be refreshing dipping into the 50s (even 60-80% chance of upper 40s in the ridges and north of I-80). && .SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY NIGHT/... KEY MESSAGES: - Dry and comfortable start to the workweek. - Temperatures below normal Monday and back toward normal Tuesday. ------------------------------------------------------------------- Dry weather continues with high confidence through Tuesday as good agreement amongst the various ensemble clusters supports rising heights as ECONUS ridging builds. High pressure migrates further east and slides overhead by Monday night. Continued dry northerly flow will provide a very comfortable, mostly cloud free day on Monday. Temperatures remain below average with ensemble probability <20% of highs topping 80 degrees. Dew points only on either side of 50 will be a nice relief from the mugginess of the past few days. Temperatures begin to rebound on Tuesday by nearly 5-10 degrees compared to Monday. Flow becomes more south of east and pushes highs back toward or a couple degrees above normal with 850 mb temperatures increasing to 14-16C. The day may also feature a bit more cloud cover, especially later in the day, as upper level moisture increases. Monday and Tuesday will be the picks of the week as a more unsettled pattern takes hold for the latter half. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... KEY MESSAGES: - Showers and thunderstorms possible Wednesday continuing through the end of the work week with the return of a more active pattern. ------------------------------------------------------------------- By mid-week, 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 late Wednesday 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 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 /22Z SUNDAY THROUGH FRIDAY/... As the front slowly crosses, convection may development towards LBE and MGW, utilizing some surface heating early this afternoon. However, confidence is still low that the terminals will be directly impacted. Hi-Res guidance suggest VFR conditions will continue to build between 18Z to 20Z for areas north of PIT. Daytime gusts will range from 20-25kt with post-frontal mixing of a tight pressure gradient. Stratocumulus decks may try to fill in late tonight/early tomorrow morning under northwest flow; especially for DUJ/FKL. .Outlook... VFR is expected until a slow moving front sets up across the region Wednesday and Thursday. && .PBZ WATCHES/WARNINGS/ADVISORIES... PA...None. OH...None. WV...None. && $$ SYNOPSIS...MLB NEAR TERM...WM/MLB SHORT TERM...MLB LONG TERM...Cermak/MLB AVIATION...Hefferan