Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 301147 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 747 AM EDT Sat Jul 30 2016 .SYNOPSIS... Low pressure will drift east through the Ohio Valley today and Sunday with a weak front trailing east to the Mid Atlantic coast and west into the Central Plains. Monday into Wednesday the low will be offshore with the front extending into the Carolinas. && .NEAR TERM /THROUGH TONIGHT/... As of 430 AM EDT Saturday... A subtle short wave seen on the water vapor loop crossing through the forecast area was generating some showers and isolated thunderstorms early this morning. This feature will be east of the county warning area by 12Z/8AM. Similar to past few nights areas of fog in the west, especially in the western valleys will dissipate shortly after sunrise. Another short wave over the Ohio Valley will cross the region today and tonight and provide some lift for showers and thunderstorms in the afternoon and evening. The eastern county warning area is expected to have the best coverage of precipitation. This is where there will be better low level convergence as well as more favorable Convective Available Potential Energy and lower Lifted Index values. Maximum temperatures today will be similar to Friday. Lows tonight will remain mild. Stayed close to MAV guidance for both periods. && .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... As of 300 AM EDT Saturday... An upper level trough centered over the Great Lakes Saturday night will track east to Lake Erie on Monday. Bulk of the dynamics and energy will remain to our north over Ohio-Pennsylvania-New York through the period. A prefrontal short waves will bring a chance for showers and thunderstorms to the region Sunday afternoon and evening. A cold front will bring another round of thunderstorms to the area on Monday. Overall chances for strong to severe storms are low each day as deep westerly flow persist each morning. Low level winds back during the afternoon across the piedmont, however westerly flow will have reduced pwats and instabilities to limit severe activity. Model pwats Sunday are around 1.60 inches and near normal (1.40 inches) on Monday. Temperatures will run near normal both days with 80s west to lower 90s east. A noticable drop in dewpoints will be felt, dropping from a week long run in the upper 60s to lower 70s down into the lower to mid 60s. && .LONG TERM /TUESDAY THROUGH FRIDAY/... As of 300 PM EST Friday... Extended range models (GFS/Euro) show upper trough over the northeast slowly lifting out on Tuesday with surface high pressure in control and generally dry conditions. Significant exception is 12z Canadian model which brings a strong short-wave across the central Appalachians late Monday into Tuesday with high chances for rainfall. Elected to discount that solution for now and go mostly dry on Tuesday with slightly lower humidity, could even see a few dewpoints under 60F in the western mountains and under 70F east, which may actually be noticeable. Temps generally seasonable for early August. Front drifts back toward the north on Wednesday with increasing pops and and humidity as heights begin to build aloft once again. With upper ridge and rising heights continuing to shift eastward Thursday and Friday should see warmer temps and higher humidities again with renewed pattern of scattered afternoon storms but nothing particularly organized. && .AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
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As of 745 AM EDT Saturday... Scattered showers and isolated thunderstorms were moving northeast across northern North Carolina and southwest Virginia this morning. MSAS analysis still showed some weak instability and CAPES around 500 J/KG in this area. With a short wave supporting this precipitation, expect the showers and thunderstorms to continue to move across KLYH and KDAN but WILL be east of KLYH and KDAN after 13Z/9AM. IFR to LIFR Stratus and fog over the mountains will dissipate by 14Z/10AM. Another vorticity maximum tracking out of the Ohio Valley will cross West Virginia and Virginia today and will trigger showers and thunderstorms this afternoon and evening. Only medium confidence on the times these storms may impact local airports. Strong gusty winds are possible with the more intense thunderstorms this afternoon. Extended aviation discussion... The region will remain in an active weather pattern into early next week. A nearly stationary frontal boundary will be across or near the region, all while a series of upper level disturbances moves along this feature through the area. By Wednesday the front may move south of the region enough to take the focus for additional showers and storms with it. VFR conditions are expected for most of the time. The exception will be temporary sub-VFR conditions under the heavier showers or thunderstorms, and during the night with patchy light fog and stratus cloud development over parts of the region.
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&& .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...AMS NEAR TERM...AMS SHORT TERM...RCS LONG TERM...PC AVIATION...AMS/PM is the U.S. government's official web portal to all federal, state and local government web resources and services.