Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 231349 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 949 AM EDT Fri Jun 23 2017 .SYNOPSIS... Tropical Depression Cindy was over Arkansas this morning and by Saturday morning will be over Maryland with a cold front trailing into the Southern Plains. High pressure builds in Sunday and Monday from the west behind the front and by Tuesday will cover much of the eastern United States. && .NEAR TERM /THROUGH TONIGHT/...
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As of 948 AM EDT Friday...Regional composite radar mosaic shows lighter showers over Charlotte and Halifax Counties exiting eastward, while another area of steady showers essentially arcs parallel to I-40/I-81 corridor in eastern TN/western VA moving to the northeast. Could see some brief, embedded localized downpours from these given the humid air mass in place. Essentially nowcasted these in the PoP/Wx grids through 17z using the 11z HRRR and a consensus blend of finer resolution guidance. This keeps scattered showers mainly west of I-81 and then eastward across Rockbridge into Amherst Counties. There have been some breaks in the clouds; while I`ve lowered cloud cover some, we probably will struggle to fully clear so kept sky cover partly to mostly cloudy at best. Question for the afternoon is if any thunderstorms can develop, still contingent on sufficient clearing to destabilize the atmosphere. Recent CAM guidance isn`t really that steadfast in indicating much thunderstorm development this afternoon. Left PoPs for the afternoon as is for now and will closely monitor forthcoming guidance for possible adjustments. Greater/heavier showers and thunderstorms projected into the later evening, hours as we await Cindy`s remnants, now over the mid-Mississippi Valley, with progressing cold front now over the Great Lakes. Previous near-term discussion issued at 345 AM Friday follows... It will take 6 to 12 hours for the former tropical system and cold front to cross through southern West Virginia and southwest Virginia. Good diffluence aloft tonight, partially with the tropical feature, but moreso with the strong upper level jet in the northern stream. Some differences in the short range models with how much precipitation there will be following the North Carolina wave and before the tropical/frontal precipitation arrives. Wildcard may be the band of showers in eastern Tennessee to southeast Mississippi and the location of this feature by this afternoon. Will be trimming back probability of precipitation for today but will retain categorical probability tonight. Limited coverage of showers and thunderstorms will also limit severe threat prior to 00Z/8PM, but with surface dew points in the lower 60s to lower 70s, leading to increased CAPE and 0-3KM helicity forecast to be up to 400 m2/s2, the threat for severe thunderstorms is still present. 850mb reach about +19 this afternoon. Should get some sun following the cluster of showers tracking out of North Carolina. Took a blend of MET /MAV guidance. Front does not completely clear the Virginia and North Carolina piedmont before 12Z/8AM. Will keep minimum temperatures mild ahead of the front.
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&& .SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... As of 330 AM EDT Saturday... Remnants of TS Cindy will get absorbed into a cold front coming across the Ohio Valley early Saturday morning. This cold front will slide across the mountains during the morning, but may not clear Southside until Saturday evening. Strong ridging off the southeast coast will slow the southern movement of the front, which will stall across the Carolina coast on Sunday. Rain showers will clear the mountains by early afternoon then move south into North Carolina during the evening. Subsidence behind the front will also bring breezy/gusty winds to the mountains through the evening. This front will remove the tropical air mass but humidities will remain slightly elevated until the dew point front moves across the region on Sunday. Dry high pressure will then take control of our weather starting Sunday afternoon. Saturday`s afternoon temperatures will warm to near normal levels. Cooler and drier air will arrive Sunday with temperatures 3F-5F cooler than normal. && .LONG TERM /MONDAY THROUGH THURSDAY/... As of 125 PM EDT Thursday... Fairly quiet wx this period with cooler temperatures as 5h trough digs across the eastern U.S. A few shortwaves in the Monday-Tuesday time frame may fuel a few showers, but overall it looks dry. Toward Thursday the upper trough exits to the east with shortwave ridging building across the Appalachians. Highs and lows Monday- Wednesday should run 5 to 10 degrees below normal, then edge close to normal by Thursday. && .AVIATION /14Z FRIDAY THROUGH TUESDAY/... As of 740 AM EDT Friday... An area of light to moderate showers will move across the mountains this morning as another batch of showers will move east of KDAN. Pockets of MVFR ceilings this morning that will improve back to VFR by 14Z/10AM. Could see an isolated shower or thunderstorm develop in the afternoon but coverage should be limited and confined to the mountains. Showers and thunderstorms associated with the remnant tropical depression and approaching cold front will reach West Virginia and Virginia late today. High confidence in the arrival time of this precipitation, with models in good agreement. Have brought precipitation with MVFR visibility back into the central Appalachians, including at KBLF, KLWB, and KBCB between 02Z/10PM and 06Z/2AM. The precipitation will move east throughout the night with MVFR ceilings expanding across the mountains behind the front after midnight. Extended Aviation Discussion... A cold front will move through central and eastern Virginia and North Carolina Saturday morning. There may be thunderstorms along the front which will produce heavy rain and gusty winds. West to east clearing anticipated through the day Saturday east of the Blue Ridge with VFR conditions and a wind shift to northwest. VFR conditions appear to continue until Monday afternoon with possible VFR/MVFR conditions in the mountains Monday night/Tuesday associated with a upper-level disturbance. && .HYDROLOGY... As of 735 AM EDT Friday... Rainfall forecast/models/ensemble river forecasts suggests greater threat for flooding will be west and north of our forecast area. Average rainfall amounts of 1 to 2 inches expected from the NC mountains to Mountain empire of SW VA to southeast WV with 2 to 3 inches further west into the KY/TN/OH corridor. Not seeing enough signals to warrant a watch, but given efficient rainfall rates, any convective elements or training will increase the threat. Timing of heavy rain will be this evening into Saturday morning. In summary, based on models looking wet, but still not high enough confidence in a flood/flash flood watch. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...AMS NEAR TERM...AL/AMS SHORT TERM...RCS LONG TERM...WP AVIATION...AMS/JH HYDROLOGY...AMS/WP is the U.S. government's official web portal to all federal, state and local government web resources and services.