Area Forecast Discussion
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000 FXUS61 KPBZ 262214 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 614 PM EDT SUN JUN 26 2016 .SYNOPSIS... Above-normal temperatures will continue through tonight. A frontal boundary will increase chances for showers and thunderstorms later tonight and Monday, with cooler temperatures expected by the middle of the week. && .NEAR TERM /THROUGH MONDAY NIGHT/...
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Strong afternoon mixing has actually entrained a bit of drier air from aloft with subsidence and high pressure in control late this afternoon. This has allowed for temperatures to surge into the 90s virtually everywhere while secondarily allowing for cumulus to fade rapidly beyond peak heating. A very strong cap is noted on RAP soundings over eastern Ohio at this time, and any convection that has tried to wander eastward from western Ohio has hit this cap and summarily died. As such, pops were removed fully from the remainder of the evening forecast. A frontal boundary is evident from near St. Louis toward Detroit at this hour with a notable wind shift along it. Convective activity along it has been anything but remarkable however as layer saturation and baroclinicity along the front is fairly paltry. As the front bears toward the area by Monday morning, scattered showers will become more common, however lacking a strong signal from any particular model solution resembling deep saturation along the front, it is not a really convincing signal for widespread rainfall. As the front sags toward the southeastern CWA by afternoon, however, diurnal instability will work to allow for showers and thunderstorms to again bloom along the front. Drier air moves in rapidly behind the front. This should allow for areas to really scatter out strongly post frontal passage. However, a lack of cold advection and strong mixing with lower dewpoints behind it will likely lead to yet another well above normal day with temperatures pushing 90F in Ohio and likely the upper 80s as far east as Pittsburgh. Fries
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&& .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... Showers and storms will wane quickly Monday night in the ridges as the initiating boundary and most of the low-level moisture shift southeastward. Except for a brief window late Tuesday afternoon when a shortwave trough crosses the region, the period through Wednesday night should remain dry. Tuesday even will see only limited precipitation owing to the decreasing moisture profile. Amid broad upper troughing, maxima this period should remain capped in the mid-upper 70s. As dry air invades on deep northwesterly flow and sfc high pressure builds, overnight temperatures will be able to drop more substantially on Tuesday and Wednesday nights than earlier in the week. Thus, minima in the 50s as indicated in numerical guidance seem very reasonable. && .LONG TERM /THURSDAY THROUGH SUNDAY/... Southwesterly flow aloft resumes on Thursday ahead of an amplifying wave in south-central Canada. This flow pattern will support a slow increase in temperature and moisture late in the week, as indicated in latest numerical guidance. Limited moisture transport ahead of the approaching wave could support modest showers and storms on Friday as the associated cold front approaches and stalls in the vicinity of the PA/MD/WV border. PoPs were increased Friday in all areas, and Saturday in the southern zones, to reflect this scenario, which is depicted in both GFS and ECMWF forecasts. High pressure is expected to build into the region next weekend in the wake of this system. The building high and departing wave should lead to a southward shift in the frontal boundary and decreasing chances for precipitation. && .AVIATION /22Z SUNDAY THROUGH FRIDAY/... VFR conditions into the first half of tonight. A shortwave and cold front will bring showers after 09Z Monday toward KZZV, and spreading east Monday morning. Only limited restrictions in any thunderstorm as the front passes. Behind the front Monday afternoon widespread vfr will quickly move southeast. .OUTLOOK /monday NIGHT THROUGH FRIDAY/... Isolated to scattered showers/storms are possible on Tuesday... which may support brief sub-vfr conditions. Otherwise...VFR conditions are expected to persist for a vast majority of the week as dry low-level air dominates. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...None. OH...None. PA...None. WV...None. && $$ is the U.S. government's official web portal to all federal, state and local government web resources and services.