Area Forecast Discussion
Issued by NWS Blacksburg, VA

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883 FXUS61 KRNK 250455 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 1255 AM EDT Mon Jul 25 2016 .SYNOPSIS... Strong high pressure aloft will continue to bring increasing heat and humidity through Monday. A series of weak surface cold fronts approaching from the northwest should gradually bring an increasing threat for showers and storms by the middle of next week. && .NEAR TERM /THROUGH TODAY/... As of 931 PM EDT Sunday... Slow moving showers and storms around Bland county into Mercer County should weaken by 11pm. The 18z local WRF showed this activity at 01z. As we head into the overnight we will see patchy fog under some high clouds, though most of these should be thin. Lows, mid/upper 60s west to 70-75 east. Previous valid discussion... Upper level ridge over the region is expected to sink south over the next couple of days. Heights over the area will be at its highest through Monday. Temperatures across the mountains will peak into the upper 80s to lower 90s with ridges being a tad cooler. East of the Blue Ridge and into the piedmont, temperatures will warm into the mid to upper 90s. Dew points across the south- central piedmont of Virginia will likely remain in the 70s, producing heat indices values near 105F. A heat advisory has been issued for this area for Monday. Otherwise expecting mainly sunny skies with convection quite limited given little support aloft and warm mid level temps. Still appears some weak low level convergence across the western ridges could combine with heating/instability to pop isolated to scattered slow moving storms across the mountain by mid afternoon Monday. && .SHORT TERM /TONIGHT THROUGH WEDNESDAY NIGHT/... As of 310 PM EDT Sunday... Slight drop in 500 mb heights is forecast by the models on Wednesday. No significant change in air mass this time frame either. 850MB temperatures do not go any lower than +18 through Wednesday night. There will be some increased low level convergence along the tail of a weak front that crosses from the northwest into the forecast area on Tuesday. While the front may stall to the north there will still be some troffing on the lee side of the Appalachians on Tuesday and across North Carolina on Wednesday. Enough daytime mixing on Tuesday and Wednesday to lower surface dew points in the afternoon. This will keep heat index values in the piedmont just below heat advisory criteria. && .LONG TERM /THURSDAY THROUGH SUNDAY/... As of 315 PM EDT Sunday... Amount of troffing in the eastern United States for the end of the week is questionable. GFS was the more amplified while the ECMWF was slightly flatter. Friday looks to be the next day with any potential for decent upper support. Will have the higher probability of precipitation on Friday and Saturday afternoon and evening. && .AVIATION /06Z MONDAY THROUGH FRIDAY/...
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As of 1240 AM EDT Monday... Similar scenario likely overnight as seen during the last couple of nights with overall VFR outside any fog at KLWB/KBCB late, and perhaps briefly at KDAN. Appears given moisture that KLWB may drop to LIFR with more IFR/MVFR at KBCB and MVFR at KDAN. Any fog or low clouds should fade pretty quick early Monday given heating with widespread VFR by mid morning if not sooner. Ridging aloft will remain in place for much of Monday with a bit better low level convergence developing over the mountains in the afternoon ahead of a weak cold front to the northwest. Given strong instability would expect somewhat better tsra coverage mainly west of the Blue Ridge during the afternoon, with perhaps some of this shifting slowly east by late in the day. Still overall coverage appears scattered to widely scattered but more clustering potential given slow movement. Thus confidence remains high enough to keep VCTS at most western sites including KBLF/KBCB and possibly KLWB by mid to late afternoon at this point. Despite loss of heating the approach of an upstream cold front and leftover instability/outflow may keep at least isolated convection going into late Monday evening. Looks like best coverage would be across the north and west but too iffy to include additional shra/tsra mention into Monday night for now. Otherwise should return to VFR outside of any leftover tsra Monday evening prior to patchy fog formation late. Extended aviation discussion... Ridge will finally weaken through mid week as an initial cold front sinks toward the area from the northwest. This should bring about an increase in daily convective coverage Tuesday into Friday with periodic MVFR/IFR possible especially Tuesday afternoon and again Wednesday pending exactly how far south the front makes it. Late night and early morning fog will likely occur at the usual valley locations, and those chances increase across the entire region if any rain occurs during the afternoon or evening at any site.
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&& .CLIMATE...
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Record high temperatures for Monday (7/25) Roanoke.....100 in 1934 Lynchburg...102 in 1934 Danville....102 in 2010 Blacksburg...92 in 1987 Bluefield....90 in 1987
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&& .RNK WATCHES/WARNINGS/ADVISORIES...
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VA...Heat Advisory from noon today to 8 PM EDT this evening for VAZ046-047-058-059. NC...None. WV...None.
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&& $$ SYNOPSIS...JH/RCS NEAR TERM...RCS/WP SHORT TERM...AMS LONG TERM...AMS AVIATION...JH/RCS/WP CLIMATE...JH

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