Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 152335 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 735 PM EDT Sun Apr 15 2018 .SYNOPSIS... A strong cold front will continue to progress across the region this evening, and offshore by early Monday. A line of showers and thunderstorms will precede the boundary this afternoon into tonight before drier air arrives overnight. Storms may be strong to locally severe. Much colder air on strong northwest winds including mountain snow or rain showers follows the front for early next week. && .NEAR TERM /THROUGH MONDAY/...
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As of 728 PM EDT Sunday... Line of strong to severe storms with some tornadic signatures is moving north from Lexington VA to Dillwyn, VA. Rest of the area appears to be done with the severe threat, but some hydro issues are still possible as main front still resides from far SW VA into wrn NC. Not expecting flash flooding, but another inch or so of rain could lead to nuisance and/or small stream flooding. However, per coordination with surrounding offices will leave flash flood watch going for now. The Tornado Watch is likely to be cancelled around 8pm. Previous discussion... Tornado Watch 53 dropped for Craig/Roanoke/Patrick and Stokes. Threat continues to the east, especially along/east of a Lexington to Smith Mountain Lake to Reidsville line. Previous discussion from an 5pm... Line of strong/severe storms along a line from Covington, VA to Roanoke to Stuart to Triad NC. Have dropped the Tornado Watch west of this line, as airmass stabilized with moderate showers expected. Severe/Tornado threat continues to the east, especially in the piedmont where better instability coincides with higher shear. Previous discussion from mid afternoon... Issued Tornado Watch 53 which includes the Piedmont of VA/NC, Blue Ridge foothills, New River and Roanoke Valleys until 03z/11pm. I`ve removed Ashe and Watauga Counties from Tornado Watch 52, which remains in effect until 7 PM. Flash Flood Watch were expanded with the afternoon package northward, per collaboration with NWS Sterling, into Bath, Rockbridge, Botetourt and Alleghany Counties in VA. Ongoing QLCS with several kinks embedded in the line extended from Mercer County WV southward into eastern SC; we are also carefully monitoring cluster of multicells moving north from the Triad into a somewhat more unstable environment in the VA Piedmont/Southside. Air mass remains highly sheared owing to strong low and mid-level wind fields. No change to prior thinking that the main threats will be damaging winds and perhaps short-lived/brief tornadoes, with hail being a secondary concern associated with supercell structures. Reported rain rates have been torrential at times and it will take training to produce flash flooding. Urban areas as well as in the western mountains where 1-hrly flash flood guidance is between 1.5-2 inches would be areas most vulnerable to flash flooding. Squall line will pivot northeast until late this evening. Threat of severe and localized hydro will continue through that period before FROPA results in more rapid SW->NE clearing. Exception will be in the mountains of southeast West Virginia where upslope rain will begin to transition/mix with wet snow overnight as temperatures begin to cool aloft. Northwest winds will be on the increase during the evening/overnight and become gusty but likely sub-Advisory, at least until early Monday morning. Cold advection, good mixing and strong pressure rises will continued to lead to an increase in northwest wind gusts. Could envision a need for a Wind Advisory for southern Blue Ridge for Monday from Roanoke to Boone. Given active weather in the first 12 hrs and that it is a late second period/early third period headline, will defer to later guidance before considering this attm. Precip will continue to fall in upslope areas as mainly a rain/snow mix with little accumulation; somewhat better chance for light accumulations of snow become more likely in western Greenbrier through Tazewell and the mountains of NW NC after this period. Highs 40s to lower 50s.
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&& .SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/... As of 349 PM EDT Sunday... Ongoing mountain -SHSN will continue to affect our western mountains counties Monday night into Tuesday, in the favored upslope areas in western Greenbrier County down into the mountains of northwest NC. Factoring in forecast snow amounts from Monday leads to forecast snow accumulations from a coating to up to 2 inches with the greatest in the western hillsides in western Greenbrier County. Present accumulations are below Advisory thresholds and are also over a long stretch of time, essentially a long-duration light snow event where any modest accumulation confined to the evening. Will also continue to have gusty northwest winds, but general trend will be for slow abatement into Tuesday. Low temperatures in the upper 20s to mid 30s Monday night, with highs into the 40s. Quieter weather anticipated for Tuesday night into Wednesday with beginning of modest warming trend into Wednesday. Lows upper 30s to mid 40s Tuesday night, while temperatures rebound in the 60s to lower 70s Wednesday && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... As of 510 AM EDT Sunday... With active weather in the near-term period, didn`t spend as much time with this forecast period with the forecast basis being from the overnight 00z and 06z model suite, along with early 12z guidance. Warming trend to temperatures continues early in the period (thru Thursday) before a cold front associated with a low pressure area/clipper system passes to our north. Chances for showers appear limited in this period. Brief cool down Friday into first part of Saturday with below-normal temps indicated. Temperatures than begin to warm along with moisture values as we await a progged strong southern stream disturbance moving out of the mid-Mississippi Valley to impact the region Sunday into Monday. This may bring another shot of decent rainfall to the region. && .AVIATION /00Z MONDAY THROUGH FRIDAY/...
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As of 730 PM EDT Sunday... Area wide rainfall, expected through early overnight, but convective heavy rain threat is abating. Still looking at poor flying conditions with IFR cigs and at times IFR vsbys. Winds will shift from the south to west as front moves through overnight, reaching BLF by 02z, LWB 03z. BCB/ROA 05-07z, and LYH/DAN 09-10z. Winds will pick up behind the front especially after 12z, but should expect sub-VFR cigs at least in the mountains through most of the period. Extended Aviation Discussion... Gusty northwest winds will continue Monday night through Tuesday along with mountain sub-VFR in low cigs espcly KBLF/KLWB. Finally looking at a return to overall VFR on Wednesday with a gusty southwest wind likely ahead of yet another approaching cold front. Next front arrives Wed night-Thu with chance of showers, with gusty winds and sub-VFR cigs again Thursday in the mountains.
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&& .HYDROLOGY...
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As of 729 PM EDT Sunday... Flash flood threat looks to be waning but areal flooding threat exists. Will not change the watch wording, and if high-res models fail to verify per weaker rates, may cancel the flash flood watch early.
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&& .RNK WATCHES/WARNINGS/ADVISORIES... VA...Flash Flood Watch until midnight EDT tonight for VAZ007- 009>020-022>024-032-033-043. NC...Flash Flood Watch until midnight EDT tonight for NCZ001>005- 018>020. WV...Flash Flood Watch until midnight EDT tonight for WVZ042>044- 507-508. && $$ SYNOPSIS...AL NEAR TERM...AL/WP SHORT TERM...AL LONG TERM...AL AVIATION...AL/JH/WP HYDROLOGY...WP

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