Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 050052 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 752 PM EST Sun Dec 4 2016 .SYNOPSIS... A combination of low pressure cross the Great Lakes region and one progressing northeast along the coast of the Carolinas, will continue to provide precipitation across the area overnight. After a brief break in the weather on Monday, our next weather system will approach and then cross the area Monday night into Tuesday. Again, after another break in the activity on Wednesday, a strong cold front will cross the region on Thursday. && .NEAR TERM /THROUGH MONDAY/...
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As of 730 PM EST Sunday... The evening update will reflect two notable adjustments. Temperatures have cooled a couple more degrees across parts of the area and placed ridge tops along parts of the Blue Ridge at or a little below freezing. We still expect a gradual increase in temperatures overnight, but until these figures start to climb, expect some light freezing rain at these locations. Also, northern parts of the region will have a bit more coverage of light sleet. As of 330 PM EST Sunday... We continue to watch both an area of low pressure moving northeast along the coast of the Carolinas, and an approaching negatively tilted shortwave trough heading through the Great Lakes region. Both of these systems will contribute to precipitation across the region into tonight. The greatest coverage will be near the VA/NC through the evening hours with the least coverage across the northern quarter of the forecast area. There is enough of a warm nose aloft for the production of some light sleet tonight, mainly along and north of Interstate 64 in Virginia. The remainder of the region is expected to receive rain. Temperatures will hold nearly steady this evening, and then begin a slow rise from roughly midnight through sunrise Tuesday. So, most locations will experience their low temperature tonight this evening will be close to the temperatures at sunset. By sunrise, temperatures are expected have increased to the lower 40s across the southwest parts of the forecast area and the mid to upper 30s across the northeast parts. The axis of the Great Lakes shortwave trough will cross the area between midnight and sunrise. Winds will shift west to northwest, allowing for the potential for some upslope precipitation to conclude the evening late tonight into early Tuesday morning between Bluefield and just west of Lewisburg, WV. The bulk of the precipitation elsewhere will end by sunrise Monday. On Monday, clouds will be on the decrease east of the crest of the Blue Ridge as northwest flow prevails and drier air begins entering the region. The upslope showers in the far western parts of the area will wane by mid-day with a trend towards decreasing cloud cover. Late Monday afternoon, look for clouds to start increasing across the area again in advance of our next weather maker that will be moving through the Gulf Coast states. Precipitation on the northeast edge of the system may reach the far southwest portion of the region very late in the afternoon. Currently, the confidence is a slight chance. Highs on Monday will range from around 50 to the lower 50s across the mountains with mid to upper 50s across the Piedmont.
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&& .SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/... As of 300 PM EST Sunday... Upper low finally ejecting out of the southwest will give rise to surface low pressure across the lower Mississippi Valley Monday night that will track just west of the mountains Tuesday. Secondary low likely to develop with convection closer to the coastal front making for an arc of widespread rainfall between the two that will overspread the region from southwest to northeast later Monday night into Tuesday before exiting Tuesday night. Expecting heaviest amounts across the west with the primary wave into Tuesday with a secondary area over the piedmont closer to the coastal low. May also see another max along the southern Blue Ridge per upslope early on. Will have to watch for some cutoff in moisture advection to the south as the second wave forms while the upper jet tends to dry slot from the southwest between the two systems. However appears enough lift over the very strong wedge to support a good soaker with an inch or more espcly south/west with perhaps a bit less to the north. Other concerns with increasing southeast flow into the Mountain Empire region early Tuesday and with possible icing across parts of Bath/Greenbrier ctys as well. Since forecast soundings show the stronger winds aloft not mixing down much due to a saturated column, appears will stay below advisory criteria for now. Latest model soundings also prog a decent warm nose over the north by Tuesday with only the ridges near freezing for a period early on. Latest EC/Nam also continue to indicate the potential for some light icing in spots so included a freezing rain mention, but quite isolated at this point. Otherwise slowed pops down a few hours given dry air aloft to start Monday night with clouds increasing, but still expecting most to see likely/categorical pops by morning. Then widespread high pops Tuesday as the core of the deeper lift/moisture crosses through the wedge making for quite a chilly/raw day with highs mainly upper 30s to mid 40s. System exits to the northeast Tuesday night with only residual evening pops northeast and across the mountains as a weak trailing boundary crosses the west with a bit of upslope induced shower coverage. High pressure to follow from the west on Wednesday as the upper flow turns zonal making for more sunshine east and overall partly cloudy west but dry. This should also help push highs back into the 50s east of the mountains with upper 40s to lower 50s west by Wednesday afternoon. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... As of 230 PM EST Sunday... Main concern with cold air arriving by the end of the week as brief zonal flow gives way to a digging upper trough and subsequent associated Arctic front on Thursday. Models continue to differ a bit on timing with the ECMWF slower per having a wave along the boundary, while consensus suggests more in the way of a drier frontal passage given westerly flow. This would bring the boundary across the mountains by midday Thursday and across the rest of the region during the afternoon. Band of moisture just ahead of the front should allow for a rain to snow shower changeover western mountains Thursday morning with a few showers east if any moisture makes it over the ridges. Strong cold advection following the front should make for mainly upslope snow showers overnight into Friday but amounts/coverage limited by very dry air. Otherwise will turn windy and much colder espcly Thursday night and Friday although appears speeds still below advisory levels with wind chills zero/single digits. Arctic high finally builds overhead by Saturday allowing for the coldest temps by early morning before the trough starts to lift out allowing some moderation Saturday afternoon into Sunday in response to return warm advection. Next weak system coming out of the Rockies may tap enough return moisture to bring a band of light mix to the far west by late Sunday. However without much southern connection appears precip limited given residual dry air and could be just clouds and spotty rain if things slow up more so only low pops for now Sunday. Expect temps to fall from west to east Thursday followed by highs only in the 20s mountains to 30s east under a blustery northwest wind Friday. Lows Friday night mostly teens unless high clouds invade more late, then warming to highs in the 30s and 40s for the weekend. && .AVIATION /00Z MONDAY THROUGH FRIDAY/...
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As of 630 PM EST Sunday... Precipitation, mainly in the form of light to moderate rain, will continue progressing across the area this evening. Ceilings are continuing to trend downward, with most locations now in the MVFR range, with some pockets of IFR across southwestern parts of the area. Visibilities have also trended to MVFR across much of the region. Pockets of sleet and light freezing rain will be be possible at some of the higher elevations, especially between KLWB-KHSP before roughly 08Z/3AM. A cold front will cross the region late tonight into early Monday morning. Look for winds to increase from the northwest around or little after sunrise. The northwest winds will bring drier air to the region. Ceilings east of the crest of the Blue Ridge should scatter by the mid-morning. Cloud cover will last longer across the mountains thanks to an upslope component working with residual low level moisture. By the late afternoon, VFR conditions are expected across the entire area. Extended aviation discussion... VFR conditions are expected Monday evening. Our next weather system looks to bring rain to the region staring late Monday night, and continue through the day Tuesday. IFR/MVFR ceilings are probably late Monday night through the day Tuesday. Likewise, sub-VFR visibilities will accompany the precipitation. Another cold front will head through the area Tuesday evening. Look for improvement to VFR east of the Blue Ridge, with lingering sub-VFR ceilings across the mountains, and perhaps some scattered upslope rain/snow showers between KBLF-KLWB later Tuesday night into early Wednesday morning. Anticipate another break in the activity on Wednesday before yet another cold front crosses the region on Thursday. Look for a return of sub-VFR conditions and better chance of snow showers in the west Thursday night into early Friday. Friday, expect a gusty day across the region with lingering upslope cloud and snow showers between KBLF-KLWB. East of the Blue Ridge, VFR is expected.
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&& .EQUIPMENT... As of 345 PM EST Sunday... NOAA Weather Radio, All Hazards, WZ2500 in Wythe County continues to be off the air. Technicians will be examining the system tomorrow to explore a possible power failure. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...DS NEAR TERM...DS SHORT TERM...JH LONG TERM...JH AVIATION...DS EQUIPMENT...DS

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