Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 250537 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 137 AM EDT Wed Apr 25 2018 .SYNOPSIS... An area of low pressure will head offshore tonight, but the Mid Atlantic will remain cool and damp. As this area of low pressure departs on Wednesday, an additional disturbance could bring more rain during Thursday and Friday. High pressure should arrive to provide drier conditions by the upcoming weekend. && .NEAR TERM /THROUGH TODAY/... As of 1014 PM EDT Tuesday...Light to moderate intensity showers continue to be predominantly confined into the central VA Piedmont into Stokes, Rockingham and Caswell Counties late this evening, along an axis of 1-1.2" PWAT axis per SPC mesoanalysis. Stronger convection which had developed this afternoon from Charlotte NC northeast to just south of the Triad has weakened considerably with air mass north of Interstate 40 being stable through wedge conditions in place; remnants are being entrained in modest low-level south-southwest moist flow moving northward. Would expect showers of light to moderate intensity to continue to move/train northward through the balance of the overnight, though will trend lighter into early morning. While rain rates are not impressive, continued rainfall will induce gradual rises on the Dan and Smith Rivers, as well as potentially lead to ponding in locations such as Reidsville, Danville and Martinsville and in poor drainage areas. More spotty/intermittent showers anticipated rest of the evening along/west of the Blue Ridge into the NC mountains near or underneath slow-moving upper disturbance moving into the central Appalachians. Saturated profile and wet soil will lead to an environment conducive to patchy mist or light ground fog. Overall a damp, rather dreary evening with temps only falling a few degrees from present values. Previous discussion issued at 300 PM follows... A closed upper level trough continues to pivot toward North Carolina this afternoon. The bulk of the steady rain spinning around this trough has progressed toward eastern Virginia and left most of our area just cloudy at this time. Meanwhile, east winds continue to keep us wedged with cool and damp air. Rainfall amounts varied considerably with this event from less than a half an inch to over four inches as shown in our earlier public information statement. Minor flooding of roads was reported in Watauga County, but creeks and streams across the entire southern Blue Ridge are currently receding. Thus, the Flood Watch will be allowed to expire at 4 PM today. While there will be additional chances of rain this evening and tonight, it should become more spotty in coverage. Locations west of a line from Boone to Lewisburg could see showers lingering all night as winds shift to the northwest. Elsewhere, rain may arrive from convection forming over South Carolina at this hour that will head toward the North Carolina Piedmont and Southside Virginia by early tonight. The stable boundary layer should inhibit any chance of thunder as this activity weakens. Expect low clouds and plenty of fog by Wednesday morning due to lighter winds and plentiful surface moisture, and it may take most of the morning to see much improvement. By the afternoon, some clearing should take place. Therefore, a non-diurnal temperature curve was utilized with a slow warm up early followed by a late surge toward sunset. && .SHORT TERM /TONIGHT THROUGH FRIDAY NIGHT/... As of 245 PM EDT Tuesday... During this portion of the forecast, the region will remain within a progressive pattern of shortwave troughs rounding the base of a longer wave trough through our region. Each of these will bring the chance of showers for about a 12 to 18 hour period as they zip through the area. The first of these is slated for Thursday night into early Friday, with the second on its heels late friday into Friday night. While there is fairly good agreement in the models regarding the placement and timing of the first system, there is much more uncertainty as to the impacts for our region regarding the second of these two features. As such, confidence in showers impacting the area Thursday night into Friday is larger than that of the second system. In fact, the difference is such that likely POPs are forecast much of the area for the first system, with the second, at this point, only associated with a continuation of at least a mostly cloudy sky and no or very little precipitation to mention. Temperatures during this portion of the forecast will average very close to normal for this time of the year. && .LONG TERM /SATURDAY THROUGH TUESDAY/... As of 1205 PM EDT Tuesday... During this portion of the forecast, we expect a transition from a pattern of a peristent trough across the eastern U.S. to one of an a building ridge. The result will be a primarily dry forecast and a trend towards higher temperatures. The one small chance for precipitation will be isolated showers on Saturday in the eastern part of the forecast, nearest the axis of the departing upper trough. The time period will start with high temperatures on Saturday ranging from the low to mid 60s across the mountains to the lower 70s across the Piedmont. By Tuesday, highs are forecast to range from the lower to mid 70s across the mountains to the upper 70s to around 80 degrees for the Piedmont region. Low temperatures for the weekend will average the upper 30s to lower 40s across the mountains and low to mid 40s across the Piedmont. By Tuesday morning, lows will range from the mid to upper 40s across the mountains to the upper 40s to around 50 across the Piedmont. && .AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
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As of 137 AM EDT Wednesday... Poor flying conditions will continue during the taf period with rain, and low clouds and fog. A vertically stacked low over North Carolina this morning will move eastward into tonight. High pressure will continue to wedged down east of the mountains today. Widespread IFR/LIFR conditions will continue across the region today with a good chance of rain at TAF sites. Pockets of fog will also develop especially this morning with some cooling and abundant low level moisture. As the upper trof starts to pull away this afternoon into this evening conditions will improve to VFR east of the Blue Ridge but expect MVFR/IFR to linger from the Ridge westward due to wind shifting to an upslope northwesterly direction. However, some breaks of sun in the east may create enough instability to get some thunder going so will mention VCTS at KLYH and KDAN toward the end of the period. Medium confidence in ceilings, visibilities and winds during the taf period. Extended Aviation Discussion... Unsettled weather conditions should continue for the remainder of this work week as another area of low pressure heads toward the Mid Atlantic. MVFR/IFR ceilings along with rain showers may take place during Thursday night and Friday. High pressure should build overhead to bring VFR conditions for all sites by Saturday afternoon. Good flying weather will persist through the remainder of this weekend.
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&& .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...PW NEAR TERM...AL/PW SHORT TERM...DS LONG TERM...DS AVIATION...KK

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