Area Forecast Discussion
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977 FXUS61 KPBZ 181405 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 1005 AM EDT Sun Mar 18 2018 .SYNOPSIS... High pressure will maintain dry weather and seasonal temperature into Monday. Low pressure is then likely to bring a wintry precipitation mix to the region Monday night and Tuesday. && .NEAR TERM /THROUGH TONIGHT/...
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No changes needed to the forecast at this time. Brilliant sunshine today with seasonable temperatures underneath high pressure. Only a few high clouds are possible tonight as the high slides east and flow aloft becomes more zonal.
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&& .SHORT TERM /MONDAY THROUGH TUESDAY/... The forecast for the short term period remains questionable due to shifting model progs/inconsistencies. Prudence thus dictates persistence and have constructed an overall forecast with a more northern precip track and precip. shield as opposed to the southward jog of the GFS. At any rate, the advance of southern stream low pressure toward the Mid Atlantic Region will increase precip. chances for Monday night and Tuesday. Initial warm advection on the van of the low looks to support rain, then a wintry mix as night falls and cooler air advects into the northern flank of an entrenching inverted trough over WV and MD. For the ridges, dynamic cooling via southeast boundary layer upslope wind, combined with the falling pressure associated with the crossing low in the predawn of Tuesday, may support more decisive and deeper cooling over the higher elevations as per the NAM depiction. Freezing rain and eventually accumulating snow is likely in that scenario before mid level support and moisture fade in the wake of the weakening mid level low/shortwave. The Hazardous Weather Outlook will be reworded for that potential and probable advisory with further caveats on warning level snow totals coming from dendrite-inhibiting warm advection into the mid levels. Shortwave ridging in advance of a digging Lower Ohio storm system should diminish POPs, at least for a spell on Tuesday, while temperature rises into the 40s on the strength of warm advection on the van of that next low encroaching over the Lower Ohio. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... ECMWF, GFS/ensemble are in general agreement on formation of a Eastern CONUS-to-coastal, southern stream trough for the mid to late week period. Given the projected weakness of the upper and mid level wind field, a damp, light snow/snow showery period is envisioned for Wednesday as cold advection in the low levels is intensified on the western flank of coastal low pressure. That unpleasantness looks to be followed by a dry, but cool period to close the work week as surface high pressure builds under northwest flow aloft. Only minor alterations were thus needed for the Superblend POP and cold temperature prognosis - which should modify as upper flow quasi-flattens by the weekend with low pressure digging over the Wrn U.S. && .AVIATION /11Z SUNDAY THROUGH THURSDAY/... VFR/SKC conditions expected through the TAF period under high pressure. OUTLOOK... Restriction potential returns with low pressure Mon night through Wed. && .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.