Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 111701 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 1201 PM EST Wed Jan 11 2017 .SYNOPSIS... Low pressure will move from the Great Lakes to the northeast U.S. today, dragging a cold front through the region. This front will stall near the Virginia/North Carolina border tonight as high pressure aloft builds across the southeast U.S. This front will return north as a warm front tonight moving back into the northeast U.S. Another front will approach the region from the north by Thursday night, then stall across northern West Virginia into northern Virginia Friday. && .NEAR TERM /THROUGH TONIGHT/...
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AS of 1100 AM EST Wednesday... Made some minor adjustments in pops and weather to match up better with WSR-88d Trends. Adjusted temperatures for this afternoon. As of 915 AM EST Wednesday... Adjusted pops with latest radar images and their trends for this morning. Utilized a blend of HRRR, HiResW-arw-east and continuity for pops late morning into this afternoon. Added areas of fog to the isc grids. Modified temperatures with sfc obs and leaned late morning temperatures towards GLAMP which captured the cooler pockets better. Temperatures will continue to increase today as 850mb temperatures are already +5C or better and will climb to around +8 to 10C by Thursday. High temperatures this afternoon will range from around 40 in the mountains to the lower 50s in the Piedmont. More changes later... As of 430 AM EST Wednesday... Going from what has been a true winter pattern into one more typical of summer as a 590dm upper ridge builds across the southeast U.S. and a series of fronts moves into or near the region and then stall, leaving a baroclinic zone in or near the area for most of the week. Hence, a cloudy, wet pattern. Temperatures will trend above normal fairly quickly after today as the region moves into the warm sector. Looking ahead, there is really no sign of any below freezing temperatures of significant now until the 24th of January! I guess you could cause this the January Thaw after the bitter cold and snow of this past weekend. Low pressure associated with a northern stream trough will move through the Great Lakes today fairly quickly and drag a cold front down into TN and NC. As the low moves into eastern Canada and an upper ridge builds across the southeast states, the front will stall just south of the NC/VA border, then return fairly quickly as a warm front tonight. Rain associated with the front this morning will drift south and especially southwest toward the TN/NC/VA borders, then return north during the afternoon/evening back across the northern parts of the CWA. The warm frontal associated rainfall will then drift north into northern VA/WV overnight. This will leave the CWA with likely to categorical pops at times today, trending toward pops decreasing toward slight chance tonight from south to north. After midnight with deep low-level moisture in place, areas of drizzle may develop from the Shenandoah Valley southwest into the New River Valley. Temperatures have risen above freezing throughout the CWA at this hour, so any threat of freezing precipitation has ended. Temperatures will continue to increase today as 850mb temps are already +5C or better and will to increase toward +10C as the week continues. However, snow pack currently across most of the CWA as a result of this last weekend`s snow storm will impact warming. Have continued to undercut MOS guidance by several degrees, especially Piedmont areas where the snowpack is deeper, until the snow pack is gone.
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&& .SHORT TERM /THURSDAY THROUGH SATURDAY NIGHT/... AS OF 400 AM EST Wednesday... The region will be in the southern stream of a split flow regime by Thursday, with a large cutoff low over the southwest and some flat ridging over the southeast. This will keep us in a mild and moist pattern with cold air bottled up well to our north. With a weak baroclinic zone just off to our west there may be a few sprinkles west of the Blue Ridge but little in the way of significant precipitation elsewhere on Thursday. High pressure moving into the Great Lakes region will push the baroclinic zone closer to us Thursday night with increasing precipitation chances west of the Ridge. On Friday, the high will wedge strongly down the east side of the Appalachians and push the baroclinic zone through the region as a backdoor cold front with a good chance of showers across the entire region later Friday into Friday night. Temperatures in the wedge look to support the possibility of some freezing rain across the Alleghany Highlands and down the higher elevations of Blue Ridge for a bit late Friday night. The wedge looks to hold firm into Saturday morning when a wave of low pressure moves out of the Mississippi valley and brings another surge of showers to locations west of the Ridge. Temperatures will be well above normal through the end of the week with highs in the low to mid 60s east of the Blue Ridge and mid 50s to around 60 degrees west. However, the developing wedge will bring much cooler conditions back to the area with highs Saturday in the low to mid 40s with warmer readings along the western and southern periphery of the wedge. && .LONG TERM /SUNDAY THROUGH TUESDAY/... .AS OF 400 AM EST Wednesday... Behind the wave of low pressure, the wedge will reestablish itself over the region through the first part of next week, then drift slowly to the east, eventually pushing a warm front through the area on Tuesday. The end result will be a persistent chance of showers accompanied by a gradual warming trend to above normal temperatures. && .AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
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As of 1200 PM EST Wednesday... Quickly changing conditions with low clouds, rain and fog will hinder aviation operations into Thursday morning. SCT to BKN MVFR clouds will continue this afternoon into tonight. Pockets of IFR and LIFR are possible in low clouds, fog and rain. A warm front with associated overrunning precipitation will lift north across the region this afternoon into tonight. As the front moves north of the region a moist air mass will be left in place over some snow covered ground this evening into Thursday morning. Expect widespread fog and drizzle to develop as a result with attendant IFR-LIFR conditions at most TAF sites throughout the remainder of the night. Look for ceilings and visibilities to rise Thursday morning. Southerly winds at 5-7 kts this afternoon will trend toward calm or less than 5kts overnight. Southwest winds at 5 to 15 kts will prevail Thursday. Winds will be gusty along the ridges Thursday morning into Thursday afternoon. Medium confidence in ceilings, visibilities and winds through the TAF valid period. Extended Aviation Discussion... Little to no improvement is expected through the period. A backdoor frontal system will work its way south into the region Friday into Saturday, maintaining the threat for additional sub- VFR in low cigs along with light rain and/or drizzle. Unsettled weather will continue into Sunday with some slow improvement in conditions as high pressure wedges in from the north, but likely still MVFR cigs at best.
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&& .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...RAB NEAR TERM...KK/RAB SHORT TERM...MBS LONG TERM...MBS/WP AVIATION...KK/RAB

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