Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 172013 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 413 PM EDT Mon Apr 17 2017 .SYNOPSIS...
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A cold front will move into eastern Virginia and North Caroline this evening and off the southeast North Carolina coast by Tuesday morning. In the wake of this front, a wedge of high pressure will build over the Mid-Atlantic region bringing noticeably cooler temperatures for Tuesday and Wednesday. Overrunning moisture will bring a threat of rain back to the southern part of the area on Tuesday and spread northward Tuesday night into Wednesday.
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&& .NEAR TERM /THROUGH TUESDAY/...
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As of 415 PM EDT Monday... Cold front has shifted to just east and south of the Blacksburg forecast area this afternoon with a line of broken convection near the boundary moving into southeastern Virginia and north- central and northeast North Carolina. Scattered lingering showers behind the front, closer to where the boundary likely is at 850mb, are expected to fade through the late afternoon into evening hours. Have moved out showers and storms much more quickly next few hours so that the tonight forecast should have no mention of thunder in for any locations, and even chances for showers are fairly low. Late tonight, an upper level wave currently over western KY will approach and bring an increasing chance for light rain back into the southwestern part of the forecast area, especially NW NC and far SW VA. Light rain could continue at times into Tuesday across parts of the far southwest and south overspreading the wedge, but think this will have a hard time getting much past the NC/VA border. Only partial clearing expected across the far north well behind the front, but most locations will remain overcast. Winds shift northeast overnight as high pressure center moves east across Great Lakes and noses southward through NY/PA and northern VA. Temperatures will be cooler tonight behind the front and with shallow wedge building in, but most noticeably tomorrow compared to the highs today. However, even with wedge firmly in place, the air advecting in from the northeast is fairly dry and some sunshine is expected at times across the northeast. In locations where is remains overcast, and additionally there is rain continue into some of the day, temperatures will be well below normal and went as much as 5 degree below coolest MAV guidance. Might have trouble getting out of the 40s in places like Boone, but most locations will remain in the 50s in the mountains, with a few low 60s in Mountain Empire, perhaps toward Bluefield, and then mid to upper 60s in the Piedmont of VA. Tricky temperature forecast and suspect some areas across the south we may need to go even cooler, while others may end up being warmer farther north.
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&& .SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/... As of 230 PM EDT Monday... A strong surface wedge will be draped across the region and stretching south into Georgia Tuesday night and Wednesday. A short wave axis over the Tennessee Valley will push moisture over this wedge starting from the southern Appalachian mountains Tuesday, then northward over southwestern Virginia Tuesday night. A surface reflection is expected to form off the North Carolina coast late Tuesday night into Wednesday. This coastal reflection and the short wave axis, moving over the southern Appalachians, will nudge precipitation east off the Blue Ridge Wednesday afternoon and east of the piedmont Wednesday evening. The best isentropic lift and upslope flow is across all of the North Carolina mountains into southwestern Virgina Blue Ridge (Floyd and Patrick counties) Tuesday night into Wednesday morning. This lift and moderate rain will track along the NC/VA border Wednesday into Wednesday evening. Rainfall amounts, especially along the eastern slopes of the Blue Ridge will range from a half to one inch. Foothill and piedmont counties along the VA/NC border should see up to half an inch. Rainfall amounts north of 460 will range from a few hundredth towards the Southern Shenandoah Valley to a quarter of an inch in the Roanoke and New River Valleys. Rainfall intensity will also vary greatly from moderate to possibly heavy rain south of highway 460 to light rain and drizzle north. Low clouds and fog will also be present Tuesday night and Wednesday morning. Saturated soils and warm moist air from a passing warm front will bring areas of fog to the area again Wednesday night. Diurnal temperatures ranges will remain small while this wedge hangs over the region. Overnight lows will be in the upper 40s to lower 50s Tuesday night and Wednesday night. High temperatures Wednesday may warm into the upper 50s to lower 60s. Areas that see the wedge erode Wednesday (Mountain Empire and Bluefield) could see temperatures warm into the upper 60s to lower 70s Wednesday afternoon. && .LONG TERM /THURSDAY THROUGH MONDAY/... As of 240 PM EDT Monday... A warm front will move north of the region on Thursday. With the wedge gone, temperatures will warm into the mid to upper 70s across the mountains and lower 80s east of the Blue Ridge. A cold front slides across the region Thursday night into Friday morning. Mostly showers will accompany the front, but a few rumbles of thunder are possible. Temperatures Friday afternoon will be slight warmer than normal, mid to upper 60s west to mid to upper 70s east. High pressure builds in Friday afternoon and will keep the area dry until Sunday. A closed low tracking east from the Midwest is expected to bring strong to severe storms to the area Sunday. Models differ on the track of the upper low but agree on timing for Sunday. This weekend`s temperatures will depend on the timing and track of the low. For now, we will keep temperatures near guidance which is near normal. && .AVIATION /20Z MONDAY THROUGH SATURDAY/... As of 225 PM EDT Monday... Weak surface front moving through the Appalachians this afternoon with light showers in the mountains resulting in MVFR CIGs at times and perhaps briefly IFR. Scattered thunderstorms forming in the Piedmont but most likely to impact KDAN with temporary MVFR conditions through about 4 or 5pm, but could move through even quicker. Also included VCTS at KLYH but this threat may be over soon as so far all storms forming east of that site. Winds shifting to NW behind the line of scattered storms in Piedmont but may switch back to SW or W briefly, and eventually will shift again NW but lighter by this evening and then eventually east to southeast overnight. A small potential exists for IFR ceilings to develop overnight/early Tuesday at KROA and KBCB, and maybe KBLF, with low level northeast to east flow developing, but confidence remains low so continuing with MVFR for now. Low CIGs are likely along the Blue Ridge southwest of KROA but the worst conditions are not likely at the TAF sites. Extended Aviation Discussion... Surface high pressure will wedge southwest into the area later Tue-Wed resulting in a more stable air mass and allowing the front to be pushed a little further south, thus no threat for convection during the Tue-Wed period with the possible exception of KBLF late Wed. Some showers could get as far north as KDAN late Tues perhaps resulting in MVFR conditions but at this time they appear more likely to remain to the south. By Thursday, the front will return north as a warm front as a new front approaches from the northwest once again. Showers and thunderstorms will be on the increase Thu-Fri as this front also drifts into the area and stalls. This front will return to the north as a warm front Saturday as a much stronger weather system moves into the southeast U.S. Between the wedge Tue-Wed and the frontal systems in/near the area through the week, multiple and extended periods of sub-VFR aviation conditions are expected through the week, but most likely by later in the weekend. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...SK NEAR TERM...SK SHORT TERM...RCS LONG TERM...RCS AVIATION...PH/RAB/SK

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