Area Forecast Discussion
Issued by NWS Greer, SC

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557 FXUS62 KGSP 290629 AFDGSP Area Forecast Discussion National Weather Service Greenville-Spartanburg SC 229 AM EDT SUN MAY 29 2016 .SYNOPSIS...
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Moisture will spread across the region today as tropical system Bonnie stalls near the South Carolina coast. Bonnie will then drift northeast along the coast of the Carolinas through the week.
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&& .NEAR TERM /THROUGH TONIGHT/...
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As of 200 AM EDT: Although the circulation center of Tropical Storm Bonnie remains just off the southeast South Carolina coast early this morning, bands of mostly light rainfall have already worked west across the piedmont and into the foothills. It is quite possible that the best convection and deeper moisture with the system could continue wrap to the northwest side of the circulation as it meanders into coastal SC today. Although this setup has the potential to produce heavy rainfall across parts of our forecast area, particularly the piedmont, the axis of any heavy rainfall remains difficult to pin down. The more eastern solution of the NAM and SREF members appears reasonable given the expected coastal track of Bonnie, but the more western GFS and its members have verified better thus far this morning. Will lean heavily on WPC QPF guidance mixed with a model blend to put the heaviest 1 to 1.5 inch stripe through tonight mainly from Chester to Monroe. In addition, the better instability will generally remain east of our area. No flood watches appear needed at this point, but the gradient in QPF could be quite sharp and it bears watching. In addition to the tropical system rainfall, upper level divergence over the mountains today should produce some scattered convection over the high terrain this afternoon. Otherwise, Bonnie should meander slowly NE along coastal SC through tonight with PoPs slowly diminishing from the southwest. Anticipate a small diurnal range on temperatures with mostly 70s this afternoon and 60s tonight except 50s in the mountains.
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&& .SHORT TERM /MONDAY THROUGH TUESDAY/... At 230 PM Saturday: On Sunday evening an upper ridge will extend from the vicinity of Bermuda to New England, while a low amplitude upper ridge will extend from the Great Lakes to the Southern Appalachians. The pattern deamplifies over the eastern USA, resulting in zonal upper level flow by Monday. By Tuesday very weak upper troughing sets up over FL, while week upper ridging sets up over the western Great Lakes, with the Southern Appalachians in between. At the surface, on Sunday evening a tropical system is expected to be near the SC coast, with substantial associated moisture spreading inland over the NC piedmont and northern SC piedmont. More limited moisture will be present over the foothills and mountains. The system moves slowly to the NC coast by Monday, with abundant moisture remaining over the piedmont until late in the day. Although the bulk of the moisture moves east of the piedmont by Tuesday, the models show enough moisture remaining over our area to support modest precipitation. At this time, precipitation amounts are expected to be limited over our area, however the Interstate 77 corridor may be subject to substantial rainfall if greater moisture associated with the tropical system spreads slightly farther inland. Instability both Sunday and Monday appears sufficient to support modest convection. Temperatures are expected to run slightly above normal. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... At 230 PM Saturday: On Tuesday night the models close off an upper low near the NC coast, associated with the tropical system moving slowly up the NC coast. Meanwhile, week upper ridging will be present over the gulf states, and an upper trough will extend from the northern plains to northwest Mexico. The upper low fills and moves northeast by Thursday, while the upper trough upstream slowly progresses. By Friday the upper trough reached the MS River Valley, and by Saturday it reaches the OH River Valley and the Gulf States. At the surface, a cold front will cross our area on Tuesday night, stalling near the coast by Wednesday, where it remains into Thursday. Moisture associated with the front may extend far enough inland to support lingering precipitation into our eastern zones. Another cold front approaches from the west on Thursday night, moving slowly over our area on Friday ands Saturday. Temperatures will fall from slightly above normal to near normal. && .AVIATION /07Z SUNDAY THROUGH THURSDAY/...
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At KCLT: tropical shower bands continue to work northwest across the piedmont early this morning, but precipitation rates have been fairly light and upstream observations show little chance of impending restrictions. Moistening from the top down should eventually lead to developing MVFR restrictions after 10Z along with steadier rain showers. Slow recovery from MVFR to lower end VFR is possible through the afternoon hours. Northerly winds will increase through the day with low end gusts likely as T.S. Bonnie moves into the SC coastline. Scattered showers from additional weak tropical bands are expected through tonight. Elsewhere: Moisture from T.S. Bonnie remains a bit more uncertain across the mountain and foothill TAF sites, but occasional showers will be likely across the foothills through at least mid afternoon before drier air starts to work back in from the southwest. MVFR restrictions look most likely later this morning at KHKY. Expect occasional northerly gusts across the foothills through the day as the Bonnie circulation reaches the SC coastline. Outlook: Bonnie is expected to move very slowly up the coastal Carolinas over the next several days. This could keep the weather somewhat unsettled across the terminal locations depending on any additional moisture wrapping westward. Lingering shower chances into early week would be greatest at KCLT. Otherwise, patchy fog chances continue at KAVL each morning, with scattered afternoon/evening SHRA/TSRA increasing throughout during the week. Confidence Table... 06-12Z 12-18Z 18-24Z 00-06Z KCLT High 92% Med 76% High 100% High 96% KGSP High 100% High 100% High 100% High 100% KAVL High 100% High 92% High 94% High 100% KHKY High 100% High 100% High 100% High 100% KGMU High 100% High 100% High 100% High 100% KAND High 100% High 82% High 100% High 100% The percentage reflects the number of guidance members agreeing with the schedule TAF issuance flight rule category. Complete hourly experimental aviation forecast consistency tables and ensemble forecasts are available at the following link: www.weather.gov/gsp/aviation
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&& .GSP WATCHES/WARNINGS/ADVISORIES... GA...None. NC...None. SC...None. && $$ SYNOPSIS...HG NEAR TERM...HG SHORT TERM...JAT LONG TERM...JAT AVIATION...HG

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