Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 211112 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 712 AM EDT Sat Apr 21 2018 .SYNOPSIS... High pressure will be over the area through the weekend. Low pressure will approach from the southwest Monday and slowly track northeast to the Virginia coast by Wednesday. This will bring widespread rain and below normal temperatures to the Mid Atlantic region the first half of next week. && .NEAR TERM /THROUGH TONIGHT/... As of 230 AM EDT Friday... Freeze warning remains in effect for the southern Shenandoah Valley this morning. Temperatures will jump above freezing by 9 AM. Surface high pressure centered along the Virginia coast, will weaken some today, but still keep the area very dry. Morning dew points are in the upper teens to upper 20s and with a light southeast wind, they will increase into the upper 20s to lower 30s this afternoon. Also helping to increase humidities will be an inverted surface trough emerging west of the Appalachains. This trough may develop some fair weather cumulus clouds this afternoon. Under mostly sunny skies and very dry air, temperatures this afternoon will warm into the upper 50s to mid 60s areawide, coolest in the higher ridges. A back-door front will stall across northern Virginia tonight. This front will bring increasing cloudiness mainly to areas north of highway 460. These clouds will help keep overnight temperatures mild in the upper 30s to lower 40s. && .SHORT TERM /SUNDAY THROUGH TUESDAY/... As of 210 AM EDT Saturday... Models still resolving the speed and track of the upper low coming out of the Southern Plains. Expect ridging over the Ohio Valley and Mid Atlantic region will lead to a slow eastward progression of the upper low. Deep moisture reaches the central Appalachians by Monday. GFS and NAM similar holding off arrival of the precipitation until after 12Z/8AM Monday. Best lift and upper diffluence will be Monday night. Upslope will also be very strong Monday night and Tuesday. Butfkit showed southeast winds from the surface through at least 5000 feet. This will bring precipitable water values of 1.0 to 1.5 inches into the foothills and mountains. In-situ wedge develops on Monday and strengthens Monday night. Wedge will remain in place until primary surface low advances to the Virginia coast and winds become northwest. The wedge and precipitation will hold maximum temperatures on Monday and Tuesday 10 to 15 degrees below normal. && .LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/... As of 300 PM EDT Friday... For Tuesday night, the question of the timing and track of the upper low continues. However, with the NAM not a player in the solutions, the resultant consensus between the GFS, Canadian and European solutions are more in line. Our rain will continue over the area Tuesday night with Wednesday looking like the point where we get on the backside of the system with the precipitation transitioning to steep lapse rate showers as the center of the low passes overhead, or close to the region. On the heels of the Monday/Tuesday system will be a fast moving northern stream system. Again guidance varies with this system as well. Solutions differ as to whether or not this system is a closed low, the GFS, an open low, Canadian, or relatively weak trough, European. Either solutions brings its associated upper system across our region Wednesday night through Thursday night, thus keeping showers to some degree in the forecast. Details to the extent can be worked on closer to the time of passage next week. Our progressive pattern doesn`t end on Thursday. Yet a third system is progged to cross the region within the northern stream jet. This one currently is expected to be more potent than the Wednesday/Thursday system. Temperatures during this portion of the forecast will again be challenging, but there is expected to be general trend toward milder conditions comparing Wednesday through Thursday, with slightly cooler conditions on Friday as compared to Thursday. All days are expected to average a little below normal for this time of year. && .AVIATION /11Z SATURDAY THROUGH WEDNESDAY/...
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As of 710 AM EDT Saturday... High pressure will control our weather through Sunday. Great flying weather expected with high confidence for VFR conditions and light winds. Extended Aviation Discussion... Clouds will begin to creep back into the area late Sunday in advance of an approaching low in the Lower Mississippi River Valley. However, cloud bases should remain VFR until deeper moisture arrives Monday. SCT MVFR showers are possible in southern Virginia and northern North Carolina Sunday night with rain becoming widespread across the Mid Atlantic region on Monday. MVFR/IFR ceilings and visibilities are expected Monday night and Tuesday due to widespread rain and an upslope southeast wind. SCT MVFR showers will continue into Wednesday.
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&& .RNK WATCHES/WARNINGS/ADVISORIES... VA...Freeze Warning until 9 AM EDT this morning for VAZ023-024. NC...None. WV...None. && $$ SYNOPSIS...RCS NEAR TERM...RCS SHORT TERM...AMS LONG TERM...DS AVIATION...AMS/RCS is the U.S. government's official web portal to all federal, state and local government web resources and services.