Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 191759 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 159 PM EDT THU MAY 19 2016 .SYNOPSIS... High pressure over the Great Lakes will move slowly south and east today and tonight. A large low pressure system will develop over the lower Mississippi Valley on Friday then track into the Mid Atlantic region on Saturday, then off the east coast by Sunday. High pressure will cover much of the eastern United States Sunday night and Monday. && .NEAR TERM /THROUGH TONIGHT/... As of 1255 pm EDT Thursday... Drier air continues to nose its way south into the region, allowing for some dissipation of cloud over in the north along with a ending drizzle in the same geographical region. The southern third of the region still is expected to get some patchy light drizzle and patchy light rain, but this too will be trending towards less coverage. Temperatures will rise more quickly across southeast West Virginia than elsewhere given the trend in cloud cover. Have bumped forecast high temperature because of this. As of 926 AM EDT Thursday... Overall forecast looks on track. Light rain/drizzle mainly across the Blue Ridge and points east and south will stay around through at least early afternoon. Some sunshine will be creeping toward Southwest Virginia west of I-77 north toward Western Greenbrier WV later this afternoon, but most will be socked in for the day with clouds. Lowered temps across the east, and as far west as the New River Valley given cool start and lack of sun. This based off the latest LAV as well. Previous valid discussion... Surface low pressure was moving away from the east coast early this morning. An inverted trof was along the western slopes of the Appalachians with high pressure in between. Little change in this weather pattern is expected through tonight. Subtle short wave tracking out of the Tennessee Valley will trigger areas of rain today and tonight, mainly in the southern half of the county warning area. Rainfall amounts today and tonight will be light. Models showed varying degrees of drier air advancing south into the forecast area this afternoon and evening. Have slowed down any clearing until later today. Based timing and southern extent of any clearing mainly on the GFS. Best probability for any sun this afternoon will be north of a Tazewell to Buckingham line. By late tonight the clouds will be returning north. Kept maximum temperatures closer to the cooler MAV guidance. Little change in 850MB temperatures and increasing dew points will hold minimum temperatures in the mid 40s to mid 50s tonight. && .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... As of 330 AM EDT Thursday... High pressure to our north Friday morning will slide east into the Atlantic ocean by Friday night. At the same time, a strong disturbance will track out of the southern Mississippi Valley to the Tennessee Valley Friday. Rich moisture and shortwaves tracking over the wedge will bring rain back into the region starting in the southwest and spreading east to the Piedmont Friday evening into Friday night. High temperatures Friday will range from the upper 50s in the mountains to near 70 degrees in the northeast. Forecast through the long term has a very low confidence value. The ECM has this low wobbling along the New England coast, while the GFS has it off the Carolina coast. Moderate to heavy rain will travel across the area Friday evening into Friday night as a shortwave move over the wedge. Precipitable water climb into the 1-1.5 inch range. the three hour FFG is relatively high with values from 1.6 to 3.5 inches. If the rain rates are high enough and training happen then there is a potential for flooding issue. WPC day three excessive rainfall outlook highlights the potential. Rainfall amounts Friday into Saturday will range from 1 to 2 inches, local higher amounts are possible along the eastern slopes of the Blue Ridge. Low temperatures Friday night will drop into the upper 40s in the mountains to the mid 50s in the piedmont. An upper level trough over the Ohio-Tennessee Valleys Saturday morning will kick the moderate to heavy rain east of the area during the afternoon. Whether this trough will be enough to completely remove the wedge is a question yet to be answered. included the mention of an isolated thunderstorm in the south Saturday afternoon to match up with some instability shown on the GFS. Clouds and rain will keep Saturday`s temperatures cooler than normal with highs from the mid 50s in the north to the mid 60s along the southern Blue Ridge mountains. Allowed for isolated to scattered showers Saturday night. Low temperatures Saturday night will drop into the mid 40s in the west to the lower 50s in the east. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... As of 330 AM EDT Thursday... A closed low develops over the Mid Atlantic Coast by Sunday night and drifts northward into midweek. Several shortwaves will rotate around the upper low, this will generate mainly afternoon and evening showers with heating under cold pool. An upper ridge will try to build east for the end of the week. Temperatures will remain cooler than normal until this low moves out to sea. As the low pulls away, look for temperatures to moderate towards the end of the week. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/...
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As of 140 pm EDT Thursday... Drier air will continue to work its way into the northern portion of the area, bringing VFR conditions to that area. Flight categories will slowly improve from north to south through the remainder of the afternoon...with most locations at VFR by 22Z/6pm. The light rain and light drizzle that is near the NC/VA border will also slowly erode. The light precipitation will linger the longest across the northern mountains and foothills of NC. Overnight, the low level moisture will condense into IFR/MVFR ceilings with some light fog possible as well in spots under a developing wedge of high pressure. After about 13Z/9am Friday, flight categories will again improve to VFR as the nocturnal inversion breaks. Rain will again start progressing into the area by the late morning across southwest portions of the forecast area. At this time, none of the TAF locations are expected to be impacted by 18Z/2pm. Extended discussion... Rain will overrun the region Friday afternoon into Friday night on the east side of an approaching upper level trough and surface low. This rain will help to strengthen the lee side wedge. Anticipate cloud cover to trend to IFR/MFVR ceilings with MVFR visibilities for rain and light fog. Saturday, the precipitation will trend more showery as the axis of the upper trough draws close and the surface low passes overhead. Flight conditions will improve as the low level winds become northwest and the lee side wedge erodes. Isolated afternoon thunderstorms cannot be ruled out as surface instability increases, especially in the west. Sunday, mainly VFR conditions are expected along with some hit or miss showers as the axis of the upper trough passes across the region. The best potential for MVFR conditions will be across southeast West Virginia where northwest upslope cloud cover is expected. Monday into Tuesday, most areas will experience VFR conditions as an upper level shortwave ridge noses itself into the area.
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&& .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...AMS NEAR TERM...AMS/DS/WP SHORT TERM...KK LONG TERM...KK/RCS AVIATION...DS

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