Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 140247 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 1047 PM EDT Tue Mar 13 2018 .SYNOPSIS... A strong upper level system will cross the region from the northwest tonight bringing snow showers mainly to the mountains overnight into Wednesday. High pressure builds in behind this feature for Wednesday night into Friday resulting in drier and warmer weather through the end of the week. Another weak area of low pressure will pass south of the area early in the weekend. && .NEAR TERM /THROUGH WEDNESDAY/...
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As of 1040 PM EDT Tuesday... No changes to Winter Weather Advisory or Winter Storm Warning at this time. An upper level low will track from the Great Lakes this afternoon, to Lake Erie tonight, then over the New England states tomorrow. This broad area of low pressure will extend south to the southern Appalachians mountains overnight into Wednesday. A strong short wave attached to this low pressure system will dig across the Tennessee Valley tonight then over the Carolinas Wednesday. With deep northwest flow and modest moisture advection, accumulating snow is likely for western slopes from western Greenbrier WV to Smyth VA. Have modified snow amounts in northwest North Carolina to a 1 to 4 inch range with the highest amounts on the western slopes. 0-3km lapse rates and BUFKIT omega forecast support potential for more intense snow showers/snow squalls in the mountains overnight. The SPC mesoanalysis of snow squall parameter is maximized over Grayson County as of 10PM. So burst of stronger wind and heavy snow are possible overnight. Most likely impact will be a quick one half to one inch of snow with any stronger snow showers in less than an hour. Little to no change made to overnight lows. A few of these snow squalls may push past the Blue Ridge and over the foothills Wednesday morning. Snow accumulations across the foothills will be under an inch, probably more closer to a dusting. Can not rule out a few flurries over the piedmont Wednesday morning as a surface wave develops over North Carolina tonight, then tracks off the coast. Waves move off the coast by the afternoon and Great Lakes trajectories turn northward to the central Appalachians. Mountain snow showers will begin to taper to flurries. Some light accumulations are still possible along western slopes, but not enough to extend advisory into the afternoon. Skies will begin to clear through the afternoon, which will help promote mixing. Breezy and gusty conditions will last into the evening.
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&& .SHORT TERM /WEDNESDAY NIGHT THROUGH THURSDAY NIGHT/... As of 200 PM EDT Tuesday... Upslope northwest flow to continue Wednesday night into part of Thursday with yet another mid level impulse sliding just north which in turn looks to result in another round of snow showers. This mainly late Wednesday night into midday Thursday. However moisture not nearly as deep or prolonged with this wave as the previous giving less digging so appears snow amounts of around an inch or so far northwest for now, and scattered snow showers farther south. Otherwise more clouds west and mainly clear east but turning blustery overnight as the pressure gradient tightens. Lows mostly in the 20s. Upslope snow showers taper Thursday while northwest winds the main issue between high pressure well to the northwest and low pressure offshore. Models also show another weak trough crossing the region with inversion levels quite low within a deepening west/northwest trajectory. This along with a 45-50 kt 85h jet that will be enhanced by a quick punch of warm advection should allow some higher speeds to mix down given strong downsloping. Thus wind headlines may be needed on Thursday so will include a mention in the HWO for now. Expect highs to bounce into the 40s to near 50 and even approach 60 east per downslope/heating of dry air. Should start mainly clear Thursday night before fast northwest flow aloft brings yet another streak of deeper moisture into the far west just north of a warm front to the southwest. Latest soundings suggest lots of dry air aloft ahead of this feature so cut back on pops with some spotty light rain/snow possible far southwest late. Elsewhere some increase in clouds with lows 20s north per less clouds and 30s south/west. && .LONG TERM /FRIDAY THROUGH TUESDAY/... As of 100 PM EDT Tuesday... Overall northwest flow to remain in place into next week which will keep the below normal temperature regime in place for the most part as the area remains along a northwest-southeast oriented baroclinic zone aloft. Models suggest a couple episodes of possible southern stream connection, mainly Saturday with a sheared wave diving southeast just south of the region, and a potential more complex wave at the end of the period. In between should remain mainly dry but cool espcly Friday with high pressure sliding in from the northwest, followed by some bump up in highs closer to normal later Sunday into Monday as a period of warm advection punches in ahead of the next impulse. Otherwise system on Saturday appears to be a light/liquid event with deeper moisture mainly south, and warm enough for rain since mainly during the day. More induced cold air with stronger low pressure by next Tuesday could introduce some frozen precip mainly north pending track, and at least some upslope snow at the end. Highs mostly 40s to low 50s Friday/Saturday, then 50s to around 60 Sunday/Monday, and 40s/low 50s Tuesday. && .AVIATION /03Z WEDNESDAY THROUGH SUNDAY/... As of 750 PM EDT Tuesday... A short wave will cross from the Ohio Valley into the Mid Atlantic region tonight. This will enhance snow showers in the central Appalachians and with a deep layer of northwest winds...upslope will be maximized on the western side of area ridges. BUFKIT for KLWB from 00Z/8PM through around 12Z/8AM showed periods of strong omega coinciding with a 30 to 40 knot jet, especially with the bands of snow showers just reaching southeast West Virginia. High confidence of brief, less than 60 min, intervals of IFR ceilings and visibility with moderate to heavy snow at KLWB and KBLF through 15Z/11AM. Snow showers and MVFR conditions will be confined to far western slopes on Wednesday with VFR conditions east of the Blue Ridge. Winds will be gusty by late morning. Wind gusts of 25 to 30 knots are likely. Medium confidence on the intensity of wind gusts Wednesday afternoon. Extended Aviation Discussion... Conditions are expected to improve in all areas by the weekend with a notable warming trend. The next chance of widespread precipitation and associated MVFR ceilings and visibility is on Saturday. && .EQUIPMENT... As of 755 PM EDT Tuesday... The Mount Jefferson NWR will remain off the air until further notice awaiting a part that was damaged during a high wind event/power outage over a week ago. Inclement winter weather could further delay the repair of this site until midweek. Please seek alternate sources for your weather information, such as adjacent NOAA All-Hazards Weather Radios (Roanoke, Hinton WV, Lynchburg, South Boston, Johnson City TN, Beckley WV, etc.), commercial sources, and the internet. You can always access our web page at && .RNK WATCHES/WARNINGS/ADVISORIES... VA...Winter Weather Advisory until noon EDT Wednesday for VAZ007- 009-015. NC...Winter Weather Advisory until noon EDT Wednesday for NCZ001- 018. WV...Winter Weather Advisory until noon EDT Wednesday for WVZ042- 043. Winter Storm Warning until noon EDT Wednesday for WVZ508. && $$ SYNOPSIS...JH NEAR TERM...AMS/RCS SHORT TERM...JH LONG TERM...JH AVIATION...AMS/RCS EQUIPMENT...AMS is the U.S. government's official web portal to all federal, state and local government web resources and services.