Area Forecast Discussion
Issued by NWS Blacksburg, VA

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165 FXUS61 KRNK 281758 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 158 PM EDT Fri Apr 28 2017 .SYNOPSIS... High pressure will build off the southeast Atlantic coast and begin a trend for warmer and more humid conditions through the upcoming weekend. A strong cold front will move through the area Monday with showers and thunderstorms, followed by some cooler, but near seasonal temperatures through the first part of next week. && .NEAR TERM /THROUGH TONIGHT/... As of 1015 AM EDT Friday... Fog/stratus continues to slowly burn off this morning, and expect it will be gone everywhere during the next hour or two. Otherwise, it looks like a quiet day with warm and humid conditions. Will be monitoring new data, especially meso models, for convective trends early tonight but high confidence in dry conditions through sunset this evening. Previous discussion... High pressure is forecast to build over the southeast CONUS today...rising heights and thicknesses resulting in warming temperatures with afternoon highs 10 to 15 degrees above normal. Dewpoints in the 50s will help maintain mild conditions during the overnight with lows tonight only dipping into the 55 to 65 degree range...quite comfortable for April. && .SHORT TERM /SATURDAY THROUGH SUNDAY/... As of 400 AM EDT Friday... During this portion of the forecast, surface high pressure will be anchored east of the coast of the Carolinas. As each day passes, a strong cold front and its parent closed upper low, will approach the region from the west, with the front arriving on Monday. The parent low at that time will be crossing the Great Lake region. The result for our forecast region will be increasing southerly winds as the pressure gradient tightens between the approaching front, and the nearly stationary offshore surface high. These stronger winds will advect both increasing moisture and warmer air aloft into the region. On Saturday, we are still expecting record, or near record, high temperatures across the region thanks to the increasing warm air advection. Please reference the CLIMATE section of this discussion for details. Isolated showers or thunderstorms will be possible by mid-day and continue into the afternoon, especially along and west of the crest of the Blue Ridge. Saturday night into Sunday, the warm air advection will continue. However, moisture will still be on the increase in the from of increased cloud cover. Sunday is expected to be cooler than Saturday thanks to these clouds, along with isolated showers and storms across the mountains. Sunday night into Monday, low level winds increase significantly ahead of the approaching cold front. By Monday morning, guidance ranges from having anywhere between a 35 to 50 kt 850mb southerly wind overhead. Anticipate a gustier day, along with increased low level shear. Cloud cover will continue to be abundant with increasing chances of showers and storms through the day. The increased shear will lend itself towards an increased chance of stronger storms. On Monday night, the front passes quickly to our east. Expect decreasing cloud cover, and drier and cooler air to progress into the region. Temperatures during this portion of the forecast will be above average during, with each day`s average slightly cooler than the prior day. On Monday, record warmth is expected with a mix of the mid to upper 80s across the region. By Monday, highs in the upper 60s to lower 70s over the mountains with mid to upper 70s over the Piedmont. Low temperatures Saturday night and Sunday night will be fairly uniform with readings in the low to mid 60s. Monday night behind the front, low to mid 50s are forecast. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... As of 400 AM EDT Friday... A general area of troughiness remains across the East Coast of the U.S. while high pressure at the surface builds into the area. Primarily dry and slightly above normal temperatures are expected Tuesday and Wednesday. By Thursday, a shortwave trough progressing through the broader trough pattern, will move into and through the Lower Mississippi then Tennessee Valleys. The result will be increasing clouds, better chances of showers and storms, and cooler temperatures on Thursday for the region. && .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
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As of 745 AM EDT Friday... Generally expecting VFR conditions through the TAF period with some MVFR possible overnight with fog/stratus development at KBCB and KLWB. There is some uncertainty as to the chances for showers/thunderstorms tonight mainly along and north of the Interstate 64 corridor as convection develops upstream and slides along a warm front. The majority of guidance is keeping the frontal boundary and associated convection to our north, but some meso guidance has the convection clipping the northern portion of the area. Believe the most likely scenario is for the warm front and convection to remain to our north, but an outflow boundary from this convection will sink into the region and may trigger a showers or thunderstorm in a small time window around Midnight. Will use VCTS at KLWB to cover this with no mention of showers/thunder elsewhere. Conditions tomorrow will be quite unstable in the hot and humid airmass but there is significant capping aloft. In the absence of synoptic forcing to break the cap, will have to rely on orographic effects/differential heating to enhance convergence and do not expect this to be overly effective. So aside from an isolated shower/storm late in the day mainly in the mountains, expecting a dry day and will keep mention of precipitation out of the TAFs for the latter portion of the valid period. Winds will generally be light Extended Aviation Discussion... High pressure should build off the Southeast coast during this weekend. Other than the potential for MVFR/IFR morning fog at the usual river valley locations, VFR conditions should prevail Saturday and Sunday. As a low pressure system approaches from the west late Sunday and Sunday night, the potential for afternoon showers and thunderstorms will increase. The cold front associated with this system should reach the Appalachian Mountains by Monday and depart offshore by Tuesday morning. As such, expect the best chance of MVFR conditions during the frontal passage.
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&& .CLIMATE... Potential for high temperature records to be broken Saturday, April 29. Current record/yearForecast Roanoke 89/1915 89 Lynchburg 88/1974 90 Danville 91/1981 89 Bluefield 83/1996 86 Blacksburg 83/1974 86 && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...MBS NEAR TERM...MBS/PM SHORT TERM...DS LONG TERM...DS AVIATION...MBS/PM CLIMATE...JR

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