Area Forecast Discussion
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073 FXUS61 KPBZ 161522 AAB AFDPBZ Area Forecast Discussion...UPDATED National Weather Service Pittsburgh PA 1122 AM EDT Wed Oct 16 2019 .SYNOPSIS... A strong cold front will bring rain to the area through mid-day. Much colder air will overspread the region behind the front, keeping temperature below average through Friday. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Light rain continues ahead of and behind the sfc frontal zone, while a focused region of moderate rain is found along a narrow band in the vicinity of the frontal zone where low-level convergence is maximized. Mid-level dry air is wrapping into the system from the west, which will lead to a rapid erosion of post-frontal rain this afternoon and a brief break in clouds. Strong cold air advection will ensue behind the boundary, leading to steady to slowly dropping temperature this afternoon and steepening low-level lapse rates. As a result, gusty nwly wind can be expected by mid-afternoon area-wide. A low-level jet will strengthen as tonight approaches, leading to stronger wind speed overnight at the highest elevations. The break in clouds will be self-defeating, as any sun will result in rapid destabilization and increasing coverage of stratocu by late this afternoon. && .SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY/... Wind Advisory was expanded to include the ridges of Garrett County with reasoning of previous forecast still applicable. Gusty nwly wind amid strong cold air advection in the wake of the cold front currently crossing the region will support deeper mixing and consequent momentum transfer to higher elevations. Wind still is expected to gust in the remaining ridge zones, but likely will remain below 40 kt except for perhaps very limited locations. Previous discussion follows... The main trough axis will swing a secondary front through the region this evening. The forcing with the boundary, and atmospheric destabilization from the cold air aloft, will promote the creation of scattered showers in the front`s wake. The risk for showers will continue overnight as another shortwave trough dives southward in the northwest flow aloft. Strong wind gusts will continue overnight and through Thursday morning. An impressive mid-level jet will dive southeastward on the back side of the eastward moving trough. Most of the winds will not mix down to the surface, but in the highest ridges of WV winds won`t need to mix down very far to reach the surface. Have issued a wind advisory tonight into early Thursday afternoon for Eastern Tucker county. Garrett county may need an advisory as well, and this can be determined as new model data arrives. Thursday will feel like late fall with clouds, below normal temperatures, and scattered rain showers. Models are indicating that snow showers are possible over the ridge tops Thursday. Forecast thicknesses and soundings are not showing an optimal setup for snow creation. Low-level thicknesses are a bit too warm and the soundings show a saturated layer well below the snow growth zone. No ice will be falling into the saturated layer, as the air above 5000ft will be dry, which will further make dendrite creation difficult. As strong orographic lift continues into Thursday afternoon, saturation heights may increase just enough to support some snow, but even the top of the cloud layer remains warmer then -7c. A forecast of rain or snow looks good for the ridge tops. Very little change in the pattern until Friday afternoon, when the cold pool aloft finally modifies and begins to drift eastward. Shower coverage will decrease Thursday night as inversion levels lower. Have held onto clouds a bit longer on Friday as warmer air to the west will be held at bay until the mid-level ridge gets here. This additional cloud cover will also support lower highs on Friday. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... A building ridge will lead to dry weather through the weekend, along with a warming trend. High temperatures will again reach the mid to upper 60s Saturday and Sunday. The models are indicating that yet another dynamically-strong system will develop over the Plains on Sunday/Sunday night and lift across the western Great Lakes through Tuesday. Details are still in dispute this far out, although increasing rain chances are certainly indicated for early next week. && .AVIATION /15Z WEDNESDAY THROUGH SUNDAY/... VFR, with local MVFR/IFR conditions will prevail in showers and a few isolated thunderstorms early on. A frontal passage through 18Z will bring a dry slot through the region, with a temporary return to VFR at all terminals. MVFR and scattered showers return this evening through tonight in W-NW flow. After FROPA, an increasing pressure gradient, mixing, and cold advection should result in gusty W wind from 20-25kt. These gusts should continue through tonight. .Outlook... Restrictions are possible Thu under NW flow and upper troughing. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...Wind Advisory from 6 PM this evening to 2 PM EDT Thursday for MDZ001. OH...None. PA...None. WV...Wind Advisory from 6 PM this evening to 2 PM EDT Thursday for WVZ514. && $$

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