Area Forecast Discussion
Issued by NWS Blacksburg, VA

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910 FXUS61 KRNK 090807 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 307 AM EST Sat Dec 9 2017 .SYNOPSIS...
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Upper disturbance moves from the Mid Mississippi Valley overhead today bringing another round or two of snow to the area. This system lifts northeast this afternoon, then another disturbance/clipper rotates into the area tonight with windy conditions and mountain snow showers. Weak high pressure builds in briefly Monday before clipper arrives Tuesday.
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&& .NEAR TERM /THROUGH SUNDAY/...
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As of 245 AM EST Saturday... Upper flow per WV loop showing deeper moisture/convection off the NC coast with some drying moving across the NC piedmont/foothills. This also depicted well on radar. Northern stream shortwave digging across the midwest looks to finally try to phase with the southern shortwave over the mid-MS Valley tonight over Virginia, but by then the main sfc low will be off the coast of New England. However, the southern stream shortwave and jet dynamics will interact with the coastal system allowing for 1-2 more bands of snow to fill back in over the forecast area by today with most high-res models favoring this taking place between 7am-4pm which is when our winter weather headlines expire. Should see another 1 to 3 inches, with higher amounts along/near the Blue Ridge, with potential for 1-3 inches into the I-81 corridor. No changes to the headlines at this time. Temperatures today should be held down again by precip/clouds so not showing much rise from this mornings readings and undercutting MOS by a couple-4 degrees, with highs in the upper 20s higher ridges to lower to mid 30s elsewhere. Should see snow tapering off in the west early this afternoon and in the piedmont by dark. The northern stream shortwave will dig across the southern Appalachians tonight with bringing a good shot of upslope snow showers along with windy conditions as it passes. Local wind study suggests near advisory level wind gusts likely in the higher mountains of NC into Mt Rogers VA. However, showing little coverage so at the moment no wind headlines will be hoisted, but could see it happening after we get past this early snow event. Snowfall from the upper wave and clipper will mainly be in the 1-2 inch range on the higher ridges of NC/SW VA and SE WV with isolated 3-4 inches possible in western Greenbrier. Per collaboration with WFO RLX and GSP will not put an advisory out for this with this morning package. This shortwave pushes east fast so looking at snow showers ending in the far west by dawn-10am Sunday. However, cold air remains. Tonight`s lows will range from the upper teens to around 20 west, to lower to mid 20s east. Sunday will stay 10-15 degrees cooler than normal with highs in the lower 30s west, to upper 30s east.
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&& .SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/...
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As of 300 AM EST Saturday... Changes were not made to this period due to busy near term weather. Previous valid discussion from Friday afternoon... Flurries may linger into the mountains thru Monday. Somewhat blustery conditions look to continue through the first part of next week as the wind field remains energized by numerous short waves zipping through fast upper level flow. Temperatures will remain well below normal into the first part of next week. Many locations will see departures of 10 to 15 degrees below seasonal norms.
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&& .LONG TERM /TUESDAY THROUGH FRIDAY/... As of 100 PM EST Friday... Amplified upper pattern featuring a western ridge and eastern trof will persist through next week, though some deamplification looks to occur toward the end of the week. The main storm track will keep areas of low pressure moving from the Great Lakes into New England with trailing cold fronts pushing reinforcing shots of cold air into the Appalachians with occasional bouts of snow showers west of the Blue Ridge. The fast moving pattern will also keep a good amount of energy in the low level wind field with blustery conditions through the period. With little change to the cold pattern in place, expect temperatures to remain well below normal through the upcoming week. && .AVIATION /08Z SATURDAY THROUGH WEDNESDAY/... As of 1150 PM EST Friday... Medium to high confidence that snow will fill back in over the central Appalachians by 10Z/5AM with MVFR to IFR visibility due to fog and snow. Axis of heaviest snow will remain east of the BLue Ridge overnight. KDAN airport has the potential for another 2 to 4 inches of snow before Saturday afternoon. North and west of the sharp precipitation gradient conditions will be VFR through Saturday morning. Expect improving conditions after 09/18Z from west to east, as low pressure begins to drift away from the region and winds become northwest. Medium confidence on this timing. Shortly after noon a clipper will cross the Appalachians, increasing the winds and bringing MVFR clouds to the mountains, including at KLWB and KBLF. Snow showers will persist overnight in the mountains with MVFR, and at times IFR, visibilities. Wind gusts up to 20-35 knots are likely at higher elevations by the 06Z end of the TAF forecast period. Extended Discussion... Strong northwest winds will continue into early Sunday. VFR conditions then return Sunday evening through Monday. Next chance for sub-VFR conditions is with a clipper system Tuesday, particularly in the western mountains. && .RNK WATCHES/WARNINGS/ADVISORIES...
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VA...Winter Weather Advisory until 4 PM EST this afternoon for VAZ009-012>014-022>024. Winter Storm Warning until 4 PM EST this afternoon for VAZ015>017-032>035-043>047-058-059. NC...Winter Storm Warning until 4 PM EST this afternoon for NCZ001>006-018>020. WV...None.
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&& $$ SYNOPSIS...WP NEAR TERM...WP SHORT TERM...MBS/WP LONG TERM...MBS AVIATION...AMS/NF

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