Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 221740 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 1240 PM EST Thu Feb 22 2018 .SYNOPSIS... High pressure will remain off the Southeast coast, promoting above normal temperatures. A backdoor cold front moving south from northern Virginia, will enter the region tonight, then return north as a warm front late Friday. A stronger front will move through the region from the Ohio Valley this weekend. && .NEAR TERM /THROUGH TONIGHT/...
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As of 1230 PM EST Thursday... Raised High temperatures this afternoon ahead of the backdoor cold front with a gusty southerly wind. Several record highs will fall this afternoon. As of 1003 AM EST Thursday... High pressure off the Southeast coast will continue our unseasonably warm weather this afternoon into tonight. Several record temperatures will be broken today. Backdoor cold front will slowly drop southward this afternoon into tonight. Adjusted temperatures utilizing latest surface obs, their trends and shaped toward NANdng/GLAMP blend. Attempted to capture the drop into temperatures with frontal boundary. Made some minor changes to pops and weather using HRRR, HiResW-arw and NAM. More adjustments later this morning... As of 330 AM EST Thursday... A strong subtropical ridge of high pressure remains anchored off the southeast U.S. coast providing our forecast area with unseasonably warm temperatures, southwest flow, and pseudo summerlike conditions. Meanwhile, a weak cold front was approaching from the west, but will make little additional progress eastward thanks to the strong upper ridge. However, the front will be close enough during the next 24 hours combined with a weak disturbance tracking around the northwest side of the upper ridge and an approaching back door front from the northeast to generate scattered showers mainly across our northern CWA from the Greenbrier Valley into the southern Shenandoah Valley and areas to the north and west. As the backdoor front arrives from the northeast this afternoon, low clouds, and drizzle and cooler temperatures will likely develop in its wake. Impacts from this front during the daylight hours will be mainly to areas north of Lynchburg and Appomattox, with the remainder of the CWA remaining south of the front. It may be until after sunset before it surges southward into Roanoke, Danville and into the northern Piedmont of NC, thus most of the CWA warming back up today similar to yesterday with near record highs. Lynchburg will probably be the only climate site that does not test records today. For tonight, the backdoor cold front will introduce a cool wedge to areas east of the Appalachian Divide that will maximize in intensity and areal coverage around daybreak Friday, then begin to retreat northward Friday afternoon. Will focus highest rain chances today along and north of I-64, then broadbrush the entire CWA tonight with the potential for light rain or drizzle associated with the backdoor front. Feel relatively confident temperatures will test 70 degrees again today for all but the northeastern CWA. After the frontal passage, favored the cooler guidance tonight, the surge of cool northeasterly wind making inroads from NoVA.
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&& .SHORT TERM /FRIDAY THROUGH SUNDAY NIGHT/... As of 300 AM EST Thursday... During this portion of the forecast, as a whole, the area will continue under a almost Summer-like upper air regime. An upper level high pressure system will be anchored off the coast of the Carolinas, while very mild and moist air streams north into the region from the central and western Gulf of Mexico. A baroclinic zone will be positioned across eastern Texas, northeast into the Mid- Mississippi Valley, and farther northeast along the Ohio Valley. Ever so slowly, the upper high will weaken and inch southeast, all while the baroclinic zone makes gradual progress toward the region, crossing it on Sunday. This general pattern points towards one that allows for almost daily chances of light rain or rain showers across at least western and northern parts of the area, with increasing chances for all locations heading into and through the weekend with the passage of a cold front. Temperatures will continue to be well above normal, averaging some 20 to 25 degrees above typical values. Guidance varies as to how quickly the front heads to the south Sunday night, and likewise, how much lingering precipitation remains over our region on its north side. Have opted for a consensus solution for Sunday night that allows for scattered showers to lingering mainly near and south of the VA/NC border. One feature will be brief hiccup in the above scenario. On Friday, we are expecting a shallow cold air damming influence along and east of the crest of the Blue Ridge. This will impact the forecast will more of a light rain, drizzle, foggy forecast through at least the morning and parts of the afternoon within this region. Areas near and north of a Lexington, VA to Lynchburg, VA line will be last to experience its impact. Cooler temperatures will also abound in this wedged area on Friday, with areas near Lynchburg reaching the lower 50s, which is actually around normal for this time of year, compared to areas like Bluefield, WV and Richlands, VA outside of the wedge, experiencing the lower 70s. A slight chance of thunder will be mentioned a little bit during this portion of the forecast. The first will be late Friday afternoon across portions of southeast West Virginia where there may be enough instability outside the influence of the wedge. Also, late Sunday afternoon across eastern parts of Southside Virginia, and neighboring north central North Carolina there may be a few thunderstorms in association with the passing cold front. && .LONG TERM /MONDAY THROUGH WEDNESDAY/... As of 145 PM EST Wednesday... Drier/cooler air follows the front for early next week as high pressure builds in Monday and wedges in from the north on Tuesday. This likely to return some clouds to the region by later Tuesday with the wedge holding into Wednesday. May see another weak shortwave pass along the boundary just to our south Monday night per 00z Euro which could bring more rain back to southern sections but iffy. Otherwise next impulse dropping out of the Rockies may tag with the front to bring another area of organized rainfall into the region by later Wednesday. Temps cooler into next week, but still above normal with highs 50s to lower 60s. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/...
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As of 1240 PM EST Thursday... Scattered to broken MVFR Clouds this afternoon will become MVFR CIGs by this evening. A backdoor cold front in northern Virginia will slow drop south this evening into tonight. In its wake, a northeasterly wind will develop with CIGS/VSBYs expected to drop into the IFR Category tonight with areas of drizzle and fog. Conditions will likely be IFR to start the day Friday and likely remain IFR to MVFR throughout the day. Winds in advance of the backdoor cool front will be S-SW 5-15 mph with gusts to around 25 mph will become northeast behind the front at 5 to 10 mph tonight. Medium confidence in ceilings, visibilities and winds through the TAF valid period. Extended Aviation Discussion... IFR and MVFR will continue into Friday afternoon. The backdoor cold front will stall along the Virginia and North Carolina line and retreat northward as a warm front toward Friday evening. VFR conditions should return for most locations during Friday night and Saturday aside from any typical low clouds along the Blue Ridge on Saturday morning. By Saturday afternoon, shower coverage should increase as a cold front arrives from the west that could bring MVFR/IFR conditions toward Sunday. Better flying weather should return later on Monday and Tuesday.
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&& .CLIMATE... As of 400 AM EST Thursday... Several record high maximum temperatures were set Wednesday. These include 77 degrees at Roanoke, 79 degrees at Danville, 76 degrees at Lynchburg, 73 degrees at Blacksburg, and 74 degrees at Bluefield. Bluefield also set its warmest ever high minimum temperature for February! Records are possible again today. Thursday 2/22/2018 Site MaxT/Year HiMin/Year BLF 67/1992 52/1980 DAN 73/1976 51/1981 LYH 73/1930 54/1913 ROA 76/1980 51/1955 RNK 65/1980 44/2017 Below are the all-time warmest minimum temperatures recorded during the month of February, for our five climate sites with long-established periods of record: Warmest HiMin - February: Site HiMin Date BLF 58 Feb 21 2018 - Broke old record of 57 from Feb 5 2008 DAN 60 Feb 18 2008 LYH 59 Feb 20 1939 ROA 57 Feb 12 1932 RNK 52 Feb 16 1990 && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...PM NEAR TERM...KK/PM SHORT TERM...DS LONG TERM...JH AVIATION...KK/PM CLIMATE...PM

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