Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 230919 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 419 AM EST Fri Feb 23 2018 .SYNOPSIS...
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A weak backdoor cold front moved through the area last night. This front will stall over the Carolinas this morning and return as a warm front this evening. A stronger front will move through the region from the Ohio Valley this weekend.
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&& .NEAR TERM /THROUGH TONIGHT/...
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As of 400 AM EST Friday... Wow factor from the above seasonal warmth will be tempered today per the passage of last night`s backdoor cool front. Front has made its way into NC, nearing the SC border. Winds in its wake are out of the ENE with the relatively cool airmass lacking enough depth to push it over the Appalachian Divide, leaving our western CWA from Bluefield into the headwaters of the TN Valley, west of Marion and Tazewell and including the NC High Country unaffected. As such, todays forecast will reflect warmer numbers in the west compared to the east. Shallow wedge of cool air is forecast to stall this morning near the SC/NC border, then begin to retreat back to the north this afternoon and evening. Little to no precipitation with or behind the wedge has been observed, however expect some drizzle vicinity of the Blue Ridge and VA highlands this morning where there is favorable uplift from the shallow ENE flow. Chance for measurable precipitation today will be mainly limited to areas along and north of I-64 where some instability will exist aloft. Even though the wedge will begin to erode from the southwest this afternoon, low-level moisture may remained trapped along and east of the Blue Ridge for much of the afternoon/evening. This will impact the temperature rise in those locations with readings only rising back to near 60, compared to yesterdays 80+. For the upper TN valley and into the Bluefield area, another record breaking day expected with temperatures reaching the mid 70s. Areas that manage to break out of the wedge, such as the western New River Valley and NW NC may also make a run for the upper 60s or test 70 degrees before the end of the day. For tonight...erosion of wedge will continue with only some remnant stratus/fog along the eastern slopes of the Blue Ridge. Southwesterly winds are forecast to increase aloft, so breezy conditions likely along the ridges with temperatures remaining AOA 50. Shower threat will primarily resided north of I-64 and west of I-77.
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&& .SHORT TERM /SATURDAY THROUGH MONDAY NIGHT/...
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As of 230 AM EST Friday... The region will continue to be under the influence of a very unseasonably mild ridge of high pressure heading into the weekend. Anticipate temperatures to continue to average 20 to 25 degrees above normal. Showers are still forecast in advance of an approaching cold front within the unseasonably warm and moist air across the region. Chances will be greatest across southeast West Virginia and neighboring counties of southwest Virginia. Chances will decrease along an gradient heading southeast into eastern portions of the forecast area. This will change on Sunday. Anticipate the front to cross the area with all locations likely to have showers. Afternoon instability across the southeast parts of the area may yield some isolated thunderstorms coincident to the frontal passage. Sunday night into Monday, model guidance varies significantly. The GFS is robust in having the frontal boundary easily exit the forecast area with precipitation not an issue Sunday night through Monday night. Most of the other operational model offer solutions of a disturbance along the Gulf Coast riding northeast along the front, and thus stalling it, just south of the forecast area. The disturbance would then buckle the front north again Sunday night into Monday with showers impacting at least the southern half of the area, if not the entire area to some degree. Our forecast during the Sunday night into Monday time frame will reflect the impact of the disturbance, but also weigh in the null solution of the GFS with overall probability of perception no higher than 40 percent across the southeast sections of the region with values closer to 20 percent over southeast West Virginia. All guidance show the region clear of precipitation by Monday night with the disturbance to our northeast and northwest winds ushering the front southeast of the region. Temperatures behind the front will trend cooler, but still above normal for this time of year. Even the more progressive GFS solutions still has readings around 10 degrees above normal Monday night.
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&& .LONG TERM /TUESDAY THROUGH THURSDAY/...
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As of 300 PM EST Thursday... Models show high pressure overhead Monday night before sliding to the coast on Tuesday. This should bring somewhat cooler and drier weather into Tuesday night with highs in the 50s/low 60s, which remains a good 10 degrees or so above normal. Fast west/southwest flow aloft looks to bring pieces of upper energy out of the southwest states by Wednesday with a couple waves ahead of a parent mid level system that will eject out into the upper Midwest by Thursday. This should result in an axis of deeper moisture lifting back north through the TN valley by early Wednesday and into our region Wednesday afternoon/night as a warm front edges north. Moisture remains in place well ahead of the trailing cold front that will approach Thursday with at least added showers around. Thus running with decent chance to low likely pops for mid week at this point. Highs again mostly 50s/60s with cooler values mountains Wednesday, and warmer readings possible Thursday east well ahead of the cold front.
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&& .AVIATION /09Z FRIDAY THROUGH TUESDAY/... As of 1230 AM EST Friday... The wedge, which most of yesterday was held up across central VA has surged southwest as expected this evening and generally is located from near LWB to BCB to MWK. Very shallow wedge will continue to filter southwest toward the SC/NC border by morning, then stall and begin to retreat back to the north Friday afternoon/evening. Little to no precipitation with or behind the wedge at this point, but would expect drizzle to develop in areas of favorable uplift, ROA/BCB/LYH, toward daybreak and into the morning hours along with MVFR visibilities in BR. Ceilings will stay in the low MVFR range much of the night, with isolated pockets of high end IFR. BLF may see low clouds/fog around daybreak with or without the wedge. Even though the wedge will begin to erode from the southwest by Friday afternoon, low-level moisture may remained trapped along and east of the Blue Ridge much of the afternoon/evening, so at this point, not expecting much improvement in cigs/vsbys through the afternoon/evening with the potential for low clouds and fog to develop again in the moist low-level air mass after 00Z Sat. Bottomline is generally poor aviation conditions through the TAF valid period with sub-VFR conditions much/most of the time. Winds will be east-northeast behind the wedge front, initially in the 10-15kt range with gusts to 20kts, decreasing toward daybreak becoming variable 5kts or less during the evening. Light southwest winds are expected to return to areas west of the Blue ridge by afternoon/evening. Medium confidence in ceilings and visibilities through the TAF valid period. Medium confidence in wind direction, medium to high confidence in wind speed through the TAF valid period. Extended Aviation Discussion... The backdoor cold front will stall along across North Carolina and retreat northward as a warm front toward Friday evening. Trapped low-level moisture will likely lead to widespread low clouds and fog with MVFR or worse conditions throughout Friday night into Saturday morning. VFR conditions are expected later in the day Saturday into early Sunday. Shower coverage and increasing likelihood for sub-VFR conditions can be expected later Sunday into Monday as a cold front approaches from the west. Sub-VFR conditions may persist into Monday as the front stalls to our south and an upper-level disturbance in the southern stream tracks across the southeast states along the front Monday. && .CLIMATE...
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Plethora of records yesterday. Please reference past Record Event Reports for details. Records still possible at Bluefield today, and within the realm of possibility at Blacksburg, pending erosion of the wedge. Thursday 2/23/2018 Site MaxT/Year HiMin/Year BLF 74/1975 51/1975 DAN 73/2017 50/1981 LYH 74/1943 52/1925 ROA 76/1943 54/1925 RNK 69/1980 46/1990
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&& .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...PM NEAR TERM...PM SHORT TERM...DS LONG TERM...JH AVIATION...RAB CLIMATE...PM

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