Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 252352 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 752 PM EDT SAT JUN 25 2016 .SYNOPSIS... Weak high pressure will continue to build into the area from the north tonight before sliding offshore Sunday into Sunday night. This should result in somewhat drier weather through the remainder of the weekend. Another cold front will approach from the west on Monday with additional showers and storms likely into Monday night. && .NEAR TERM /THROUGH SUNDAY/... As of 740 PM EDT Saturday... Shower activity was limited early this evening to parts of Greenbrier County WV and the Northern Mountains of North Carolina. Little in the way of additional areal coverage is expected as we approach and then pass sunset. With sunset will come a gradual trend in decreasing coverage. By midnight, these isolated showers are expected to have dissipated. Temperatures will fall into the low to mid 70s by midnight. As of 218 PM EDT Saturday... Seeing low clouds gradually eroding from west to east this afternoon with the help of heating and easterly mixing as high pressure to the northeast slowly builds in. Latest analysis also showing limited instability due to earlier clouds with only weak moisture convergence across the south/southwest where have see shallow/isolated showers develop from time to time. Latest meso models continue to limit added convective coverage under the dry air aloft seen on water vapor with focus mainly along the I-77 corridor and far southern sections where could pop isolated coverage through sunset but iffy. Otherwise expect clouds to diminish over the next few hours before perhaps seeing another swath work westward toward the Blue Ridge overnight within the onshore flow. However with even added drying aloft, expecting less widespread low clouds, with patchy fog in the valleys, and out east if clouds are less. Low temps should be similar if not a little cooler under a bit more clearing with upper 50s to lower 60s likely. Axis of the surface high from offshore will become stronger across the region Sunday under building heights aloft. This should again tend to put a lid on convection as guidance showing even less instability and better drying through the column per latest forecast soundings. Appears an isolated shower or two not totally out of the question over the far west where weak convergence under low level southeast flow will be best. However since moisture quite shallow, chances limited so lowered pops even more. Elsewhere should be mainly sunny after low clouds/fog fade and a little warmer under more insolation/warming aloft. This should push most spots outside of the higher elevations into the more uniform 80s across the board. && .SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/... As of 245 PM EDT Saturday... Ridging both surface and aloft will begin to slowly break down Sunday night as the onset of a digging upper low well to the northwest starts to shift a surface cold front toward the region late. Latest model timing would suggest that most of Sunday night should stay dry with the arrival of the leading edge of any pre-frontal showers holding off until after daybreak if not longer. Guidance then shifts a deeper axis of moisture across the region from Monday afternoon into Monday evening with progged pwats of around 2 inches within a narrow band. Rather slow steering aloft would suggest another round of slow moving showers and storms with progs indicating qpf of another .50 to more than an inch across the region which is of concern over/near areas that received flooding last week. Thus plan to add mention to the HWO about heavy rainfall for now. Otherwise overall shear and instability look quite marginal which may help out with less severe and perhaps organization for heavy rainfall. Thus will keep a broad swath of likely pops most areas from west to east Monday into Monday evening with coverage tapering behind the front later Monday night. Highs closer to the warmer side of mos given the slower expected arrival of clouds/showers on Monday. && .LONG TERM /TUESDAY THROUGH SATURDAY/... As of 1230 PM EDT Saturday... Broad upper trough will re-establish over the region by midweek and persist into next weekend as added impulses rotate through bringing periodic rounds of showers/storms after midweek drying. Secondary cold front looks to cross Tuesday under the leading edge of initial digging shortwave energy that will represent the arrival of somewhat cooler/drier air Tuesday night into Thursday. Appears perhaps enough lingering moisture to support some chance of showers and possible storms later Tuesday espcly south/east with less across the mountains. Pocket of cool advection progged at 850 mb should arrive Tuesday night into Wednesday on drier northwest flow and better subsidence making for a couple of cooler overnights and a mainly dry Wednesday. More uncertainty in regards to rain chances will develop Thursday-Saturday as moisture returns and added impulses swing toward the region around the residual upper system to the north. Latest models have backed off on much organized convection with more in the way of mostly diurnal showers/storms each day. This supports the return of mostly low chance pops with the region still under weak high pressure between the initial boundary to the south, and another front swinging in from the north by day7. Temps to remain near seasonal overall except slightly below midweek with some comfortable overnights as well given lows 50s to near 60. && .AVIATION /00Z SUNDAY THROUGH THURSDAY/...
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As of 745 PM EDT Saturday... Aviation conditions generally expected to improve through the TAF valid period, but there will still be areas of low clouds and fog overnight and into the mid-morning hours Sunday. High pressure will remain anchored along the Mid-Atlantic seaboard through the period, gradually drifting southward. This will keep a maritime easterly flow across the forecast area through the TAF valid period. Potential exists for mainly low clouds and some fog to develop again overnight, but confidence in such as less than last night/Saturday morning. Somewhat drier air appears to be advecting southwest through the region as winds tend to back to the northeast overnight, then veer back to the southeast after daybreak Sunday. Will continue with previous concept of some low clouds/fog developing overnight, generally MVFR at most locations, but potential for IFR-LIFR, mainly at KLWB/KBLF. Confidence in low clouds/fog forming is least at KLYH/KDAN. Cigs should improve by mid to late morning Saturday, leaving mid-level CU and VFR conditions most sites after 17Z. Not expecting any showers or thunderstorms Sunday. Winds ENE 4-7kts overnight, becoming ESE-SE 6-8kts after 14Z Sunday. Medium confidence in cigs and vsbys through the TAF valid period. Medium to high confidence in wind dir/spd through the TAF valid period. Extended discussion... The next cold front will move into the region early Monday, then move slowly through the CWA Monday into Monday night. Appears most showers will stay west of the region Sunday night with sub- VFR developing mountains by Monday afternoon, and continuing across the region at times into at least Monday evening. Widespread showers/storms should exit Monday night giving way to more isolated coverage including periods of MVFR Tuesday with a passing secondary cold front. Expect a return to more widespread VFR behind the front on Wednesday.
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&& .HYDROLOGY... As of 305 PM EDT Saturday... Extensive flood damage has occurred especially in Greenbrier county West Virginia and some roads remain impassable. A flood warning remains in effect through 630 pm this evening as flooding continues especially between Rupert and Rainelle with lots of standing water across the region as well. Water levels are continuing to recede along the Greenbrier River as well as other smaller creeks and streams which should finally help alleviate any ongoing flooding this weekend. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...JH/RCS NEAR TERM...DS/JH SHORT TERM...JH LONG TERM...JH AVIATION...JH/RAB HYDROLOGY...JH is the U.S. government's official web portal to all federal, state and local government web resources and services.