Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 162019 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 319 PM EST Tue Jan 16 2018 .SYNOPSIS... A cold front will move through the region overnight into Wednesday morning bringing measurable snow and very cold temperatures to the area. High pressure will build into the region through the weekend, along with dry weather and milder temperatures. A potent cold front will cross the area on Monday, bringing a line of moderate to heavy rain showers, some with very gusty winds. && .NEAR TERM /THROUGH WEDNESDAY/... As of 230 PM EST Tuesday... A positive tilted trough draped over Ohio Valley southwest to the Ozark, will slowly push a cold front over the region tonight into Wednesday morning. This front will also be slowed by a series of reflections developing along the front, tracking to the northeast. The upper level trough will move over the mid Atlantic region Wednesday afternoon pushing the front and snow off the coast. Associated with this front will be snow, wind, and cold temperatures/wind chills. As the front drifted over West Virginia and western Kentucky today, snow amounts ranged from 2 to 5 inches. Slightly lesser amounts (2-4 inches) are expected in our extreme western counties (Tazewell VA to Greenbrier WV) this afternoon into tonight. Accumulating snow will taper to flurries during the early morning hours Wednesday, ending as early as sunrise. As the front moves to the Blue Ridge this evening, jet dynamics develop south and east of the area overnight. This will create a precipitation minimum over counties along the Blue Ridge and foothills, where less than an inch of snow is expected. Snow is expected to taper to flurries around sunrise, ending by late morning. Waves tracking along the front after midnight will bring accumulating snow to the piedmont counties of south-central Virginia and northwest North Carolina. Snow should taper to flurries by late morning, ending by early afternoon. Accumulations will range from 1- 3 inches. For this forecast package, there are no changes to any headlines. Advisories in the west and east for snow remain in place through Wednesday morning. Unless the forecast changes overnight, a special weather statement will be issued for counties bordering the Blue Ridge for possible minor travel impacts. A tight pressure gradient develops behind the front, but until clouds can clear, most of the strongest winds will remain above 3000 ft. As the inversion lowers towards morning across the mountains, winds will blow 15-25 MPH with gusts up to 35 MPH through the day. These winds will likely blow snow on to treated roadways. Wind coupled with very cold temperatures will also send wind chills values below zero across the higher elevations to the single digits in the mountain valleys Wednesday morning. Light southwest winds and more sun than previously expected allowed temperatures to warm into the upper 30s to lower 40s across the mountains. Temperatures over the foothills and piedmont counties warmed into the 40s. Despite the warmer temperatures, snow accumulations should not change much as temperatures will drop due to evaporative cooling this afternoon and evening. Cold air will enter the mountains overnight with temperatures dropping into the 10F-20F range. Cold air will continue to surge in during the day tomorrow. Mountain temperatures may only warm 5F with highs ranging from 15F to 25F. Cold air will make it east of the Blue Ridge while temperatures will only drop into the 20s. Downsloping winds and sun in the afternoon should allow temperatures to warm into the upper 20s to lower 30s Wednesday. Areas with a 2-3 inch snow pack will be cooler by 3F-5F. && .SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/... As of 130 PM EST Tuesday... At start of Wednesday night, the center of the upper level low/trough partially responsible for Tuesday night and Wednesday`s snowfall, will be directly overhead. As its shifts east overnight, gusty northwest winds will help maintain some upslope snow showers and flurries over portions of southeast West Virginia. However, the trajectory will be a little bit more north than true northwest, so the impacts of the upslope will not be maximized. Regardless, much drier air is progged to quickly enter the region thus minimizing what uplsope there will be. During the day Thursday, the prevailing flow will back to the west and the overall synoptic pattern will be a near zonal flow across the area. This pattern will continue through Friday will gradually increasing heights/temps as a shortwave ridge starts to build over the central potions of the nation. Temperatures will trend milder during this portion of the forecast with readings averaging some five degrees above normal by Friday. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... As of 1215 PM EST Tuesday... Heading into the weekend, an upper level trough will begin to deepen over the Four Corners region and eject into the Central Plains states, all while upper level ridging builds over our part of the country. Concurrently, the low level temperature profile will gradually warm as southwest flow warm air advection is forecast. Also, moisture will increase across our region, especially the western sections. The result will be a period of increasing temperatures, with limited chances of precipitation. Only the far western sections of the area will have mention of some isolated showers both Saturday and Sunday afternoon. High temperatures by Sunday are forecast to range from the mid to upper 50s across the mountains with upper 50s to around 60 across the Piedmont. Sunday night through Monday night, the Central Plains trough is expected to close off, and lift rapidly northeast into and through the Great Lakes region, and then into southeast Canada. Its associate surface cold front is progged to progress through our region Monday afternoon and evening. Anticipate a well defined line of showers to cross the area during this time frame, along with the potential for some gusty winds based upon an associated 40 to 50 kt jet crossing the area both pre- and post- frontal passage. It may be a scenario very gusty showers crossing the, with decent cold air advection in the wake of the system. A mix or change over to snow is expected in the west Monday night. By Tuesday, the system is expected to east of the region, with low level winds backing rapidly during the course of the day, thus shutting off any northwest flow upslope in the west early in the morning. Temperatures Monday into Tuesday will trend cooler, but still average about five to ten degrees above normal for this time of year. && .AVIATION /20Z TUESDAY THROUGH SUNDAY/... As of 1230 PM EST Tuesday... A positive tilted trough draped over Ohio Valley southwest to the Ozark, will slowly push a cold front over the region tonight into Wednesday morning. This front will also be slowed by a series of reflections developing along the front, tracking to the northeast. The upper level trough will move over the Mid Atlantic region Wednesday afternoon pushing the front and snow off the coast. Ceilings are starting to lower in the far west (BLF-LWB), but remain VFR. Ceilings will lower to MVFR in the far west by mid afternoon and continue to stay until early Wednesday morning. Ceilings lower to MVFR towards the Blue Ridge (BCB/ROA) this evening then recover to VFR by morning. Piedmont counties (LYH/DAN) to lower to MVFR by sunrise and rebound to VFR by mid afternoon Wednesday. Snow may also reduce visibilities during periods of MVFR ceilings. Pressure rises behind the front will bring winds of 15-25 kts with gusts up to 35 kt along elevations above 3kft. As inversion lowers and skies become mostly clear, these winds will mix to the lower elevations through the day Wednesday. Moderate turbulence is likely along the Blue Ridge. Extended Discussion... Dry air will restore conditions to VFR by Thursday under high pressure. VFR conditions should persist into the weekend with warming temperatures. Moisture will return to west Sunday night into Monday. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...Winter Weather Advisory until 10 AM EST Wednesday for VAZ007- 009-010. Winter Weather Advisory until 3 PM EST Wednesday for VAZ034- 035-043>047-058-059. NC...Winter Weather Advisory until 3 PM EST Wednesday for NCZ004>006. WV...Winter Weather Advisory until 10 AM EST Wednesday for WVZ042>044-507-508. && $$ SYNOPSIS...DS NEAR TERM...RCS SHORT TERM...DS LONG TERM...DS AVIATION...RCS

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