Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 131107 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 707 AM EDT Fri Oct 13 2017 .SYNOPSIS... High pressure will continue to wedge south along the lee of the Appalachians today and tonight. A cold front will approach the area this weekend, and finally cross the region Sunday night into Monday. High pressure will build over the area for the early to middle part of next week bringing cooler and drier weather for much of next week. && .NEAR TERM /THROUGH TONIGHT/... As of 300 AM EDT Friday... Strong wedge remains in place this morning with earlier soundings showing saturation including easterly flow up to above 800 mb. This cool air damming also being aided via spotty light rain/drizzle as combination of weak eastern overrunning and western upslope continues. Expect this trend to persist at least through the morning with best chances for measurable rain lingering across the south and east as a faint perturbation works up along the eastern slopes within the cool pool. Thus keeping low likely to high chance pops except less heading west where the wedge is much weaker from the Mtn Empire region north into West Va. Parent high slides east off Nova Scotia this afternoon allowing for an overall slow weakening of the wedge espcly mountains where the flow aloft will turn more southerly. However appears that low clouds will hold as moisture looks to remain locked in under the steep subsidence inversion seen off latest soundings. Decreasing depth of the moisture should gradually shut off lingering rain/drizzle as well which could help some breaks develop later espcly western third. Otherwise will have decreasing pops this afternoon with more spotty drizzle likely persisting Blue Ridge east which could linger into the evening as the wedge flops back after loss of heating. Will keep highs near seasonal levels, mostly 60s with only slight rises likely east, with better potential to reach 70 from MKJ to BLF and perhaps LWB if clouds diminish more. Shallow moisture to remain trapped in most spots overnight with any afternoon clearing likely filling in with low clouds and some spotty drizzle/fog overnight as a weak bubble high redevelops overhead. Lows mostly uniform in the 50s given saturation and very light easterly flow under the cloud cover. && .SHORT TERM /SATURDAY THROUGH MONDAY NIGHT/... As of 300 AM EDT Friday... The parent high pressure supporting the wedge will continue moving off the New England coast on Saturday. This will weaken support for the wedge east of the Appalachians and allow for some improvement, though the wedge may get a boost with cooling Saturday night with a resurgence of clouds and some fog. Low pressure moving into the Great Lakes region will push a cold front into the area late on Sunday, with the front making slow progress across the region Sunday night. This looks to bring a good chance of showers along with some breezy conditions to the forecast very late Sunday and into Sunday night. The front will be in no great hurry to exit Monday so some lingering showers east of the Blue Ridge especially out toward Southside Monday morning. Noticeably cooler and drier air will then start moving in on a northerly breeze behind the front later on Monday and Monday night. Temperatures will remain well above normal ahead of the front with highs in the low/mid 80s east of the Ridge and mid 70s/around 80 to the west. Behind the front we will cool down a bit below normal with highs in the upper 60s/near 70 east, upper 50s/middle 60s west. && .LONG TERM /TUESDAY THROUGH THURSDAY/... As of 240 PM EDT Thursday... Cooler high pressure builds in and sets up residence into Thursday. Temps will start to modify a little by midweek, but still at or just above seasonal norms. && .AVIATION /12Z FRIDAY THROUGH TUESDAY/...
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As of 705 AM EDT Friday... Poor flying conditions under MVFR to IFR cigs and ocnl MVFR vsbys will persist through much of today. 500-1500 foot bases should be common with periods of lower cigs within areas of light rain/drizzle including mountain obscuration. May also see periods of 1-4SM in rain/drizzle and/or fog mostly during the morning as well. Any light rain/drizzle/fog should diminish by mid to late morning, though MVFR to IFR ceilings to remain with no meaningful change except perhaps seeing cigs approach VFR at times along the KBLF-KLWB corridor this afternoon as the western periphery of the wedge weakens a bit. Northeast winds 5-12 kts through the TAF period. Wedge to linger tonight with any improvement in cigs during this afternoon likely to give way to more low end sub-VFR with loss of heating as the cool air wedge enhances again overnight. Extended Aviation Discussion... Saturday, the lee side wedge will give way to increasing southwest flow ahead of our next synoptic scale upper trough and associated cold front. This will allow for more areas to experience VFR conditions, a trend that will continue into Sunday. Sunday night into Monday, a substantial cold front is expected to cross the area with scattered showers and some storms. Sub- VFR conditions are expected to accompany the stronger showers/storms. Also, in the wake of the cold front, lingering moisture in the west will likely manifest as some upslope sub- VFR ceilings Sunday night into Monday morning. High pressure will continue to build into the area on Tuesday. Other than some early morning patchy mountain and river valley fog, VFR conditions are expected.
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&& .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...DS/JH NEAR TERM...JH SHORT TERM...MBS LONG TERM...WP AVIATION...AL/DS/JH is the U.S. government's official web portal to all federal, state and local government web resources and services.