Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 231421 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 1021 AM EDT Sat Sep 23 2017 .SYNOPSIS... High pressure over the eastern United States will continue to bring warm and dry weather to the region through the first part of next week. A cold front is forecast to cross through the area on Wednesday or Thursday. && .NEAR TERM /THROUGH TONIGHT/...
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As of 1015 AM EDT Saturday... Latest satellite imagery shows mainly sunny skies with overnight fog/stratus just about gone. Anticipate some short wave energy may combine with diurnal instability and orographic forcing to bring a slight chance of an isolated shower or thunderstorm mainly across the mountains of NC, but overall a dry and warm first full day of fall. Expect highs to reach the mid 80s to near 90 east of the Blue Ridge with low/mid 80s to the west. Previous discussion... Center of upper ridge moves from Michigan to Pennsylvania today and tonight. 500MB heights rise over Virginia and North Carolina. Cooler air aloft shifts to the southwest today. Better instability and higher CAPES remain just south of the Virginia border this afternoon. Have left a low probability of precipitation in that region this afternoon. Mid and high clouds From Maryland to Kentucky and tennessee see move out of the area this morning. Models showing another batch of low level moisture advancing into the piedmont and foothills of Virginia and North Carolina again overnight. This may a be where fog a low clouds form overnight. More fog again expected in the favored areas in the mountain valleys late tonight. Used persistence in forecast of afternoon highs and overnight lows.
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&& .SHORT TERM /SUNDAY THROUGH TUESDAY/... As of 330 AM EDT Saturday... Model guidance this period remains in generally good agreement on synoptic scale features, though a bit more uncertainty on cloud cover, winds and high temps into Tuesday/midweek in our far southeastern counties. Pattern features a large-scale ridge centered over the northern Mid-Atlantic and southern New England, with a weak closed upper low generally over western TN/MS/AL. A continuation of dry conditions and summerlike temperatures appears to remain the case in this period. Focus then turns to Hurricane Maria`s eventual interaction with the aforementioned large-scale features. 00z deterministic global guidance has shown a slower forward motion and a shift in center track slightly west. Some guidance indicates some far fringe effects - a modest increase in northeast winds and multi- layered cloudiness - into Southside as early as Tuesday. That being said, Maria`s closest approach to the Atlantic seaboard appears to be around midweek (i.e. after the short-term period) with no significant impacts projected in the interior. Interests are encouraged to monitor the latest forecasts specific to Maria from the National Hurricane Center. Overall stuck with a persistence forecast for Sunday and Monday, with dry conditions and mostly sunny skies leading to highs into the mid/upper 80s. Lows should be commonly in the upper 50s to mid 60s, though a couple degrees milder Monday night. Given a bit more uncertainty this morning on western extent of cloud cover Tuesday, did opt to lower highs a bit into the low 80s from Amherst County VA to Rockingham County NC eastward. GFS-based BUFKIT soundings around Danville and Farmville show east-northeast winds in the 900-700 mb layer around 30 kts Tuesday. Don`t think these will fully mix but did increase wind gusts slightly to around 20-22 mph in the Southside and Caswell County NC...essentially a moderate afternoon east-northeast breeze. && .LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/... As of 250 PM EDT Friday... Recent guidance continues to point to Maria`s closest approach to the Chesapeake/coastal Carolinas on Wednesday. Though the current expectation is for no significant effects from Maria aside from a modest increase in northeast to north winds in our far eastern counties, will need to carefully monitor how close Maria`s circulation gets to the Atlantic seaboard. Otherwise, with subsidence still in place, don`t expect much in the way of shower activity, but cloud cover as a whole should increase, especially for those East of the Blue Ridge. A Persistence forecast trend in temperatures will continue through this time period. A cold front approaches from the north and west on Thursday, bringing the possibility of isolated to scattered showers across the area. Timing of the front, at least in the eyes of the GFS, doesn`t look favorable for significant shower coverage or intensity, but it should be enough to push the remnants of Maria far enough off shore to break us free from the easterly flow. Drier and more seasonable conditions should follow the front, and continue into the weekend. && .AVIATION /14Z SATURDAY THROUGH WEDNESDAY/... As of 720 AM EDT Saturday... Mid and high clouds have cleared out from southwest Virginia and northern North Carolina. Coverage of MVFR fog expended as the clouds moved west of the area. Similar to past few mornings, several observations, including KBCB and KLWB had LIFR visibility. KBLF has also cleared out and looks close to fogging in. Like on Friday morning, high confidence that much of the fog and any stratus will burn off by 14Z/10AM. Strong high pressure will build in today. This will keep any threat of isolated afternoon thunderstorms along the North Carolina/ Tennessee border. Once again little cloud cover and calm to light and variable winds this evening will result in MVFR to LIFR fog in the mountain valleys overnight. GFS and NAM suggest an areas of higher low level moisture may move into the piedmont overnight. Have some MVFR fog at KDAN but confidence is low. Extended Aviation Discussion... Overall persistence forecast Sunday into early next week as strong high pressure aloft builds in from the northwest keeping tropical moisture offshore. This should also maintain good flying conditions along with mostly dry weather, outside of any late night/early morning fog from Sunday through Wednesday. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...MBS NEAR TERM...AMS/MBS SHORT TERM...AL LONG TERM...JM AVIATION...AMS/JH

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