Area Forecast Discussion
Issued by NWS Greer, SC

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000 FXUS62 KGSP 280259 AFDGSP Area Forecast Discussion National Weather Service Greenville-Spartanburg SC 959 PM EST Mon Feb 27 2017 .SYNOPSIS... Southerly flow has returned temperatures to above-normal. A warm front will lift north through the area Tuesday warming temperatures further and then a cold front crosses the area Wednesday night with generally light rainfall. Cool high pressure behind a late week reinforcing front returns temperatures to near normal briefly Friday and Saturday but temperatures rebound quickly Sunday and Monday back to above-normal as the high slides offshore. && .NEAR TERM /THROUGH TUESDAY/... As of 945 PM EST: KGSP radar shows that light precip...mainly aloft...has moved to the east of the fcst area. The latest model guidance is not as keen on developing light precip overnight. Although weak isentropic lift is maintained, the moisture is just not there any more, so the lift is not terribly productive. There is still a small chance in the SW upslope areas of the srn mountains of NC, but that is about it. Will use this update to remove the slight chance of precip across most of the area, while leaving the low precip chances in the little TN valley and northeast GA. Temp trends are all mixed up as we have kept the overcast over the east, but opened some holes near the Blue Ridge. Min temps should remain fairly warm as the clouds should return overnight. Upper heights will recover a bit through Tuesday. Low level moisture will persist mainly over the mountains with a continued low level southwesterly upslope flow. Slightly deeper moisture will return again from the west to affect mainly the mountains in the deep layer SW flow through Tuesday afternoon. Upslope triggering there may keep scattered showers going through the day, with an isolated thunderstorm possibly in the far southwest mountains during the afternoon. Piedmont lapse rates should spike around 6.5 deg C/km with SBCAPE values around 400 J/kg during the afternoon, but triggers for convection will be hard to find in the lower piedmont. Will keep PoP generally slight chance east of the mountains. Max temperatures should reach at least 10 degrees above climo. && .SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/... As of 230 PM EST Monday: The forecast area on Tuesday night will will be between high pressure off the east coast and low pressure over the Ohio Valley/cold front trailing into the lower Mississippi Valley. Warm southwest flow and cloudiness will keep overnight lows in the 50s even at the highest elevations. A few showers are possible with the highest probability in the North Carolina mountains. The cold front will advance eastward on Wednesday reaching the western parts of the forecast area late in the day. A very warm day is in store with highs in the middle 70s outside of the highest elevations. Showers and thunderstorms will spread across the northwestern half of the forecast area in the afternoon and then move across the rest of the area Wednesday evening. The wind fields with the storms Wednesday afternoon and evening will be impressive with 40-50 knots of 0-3 km shear expected. However, the thermodynamic environment will be weak with CAPES of only 300- 400 J/kg expected. Thus, any storms that organize may be capable of producing wind damage. Will maintain the mention of severe weather possible in the Hazardous Weather Outlook. The cold front will move east of the area by midnight allowing cooler and drier air to move into the forecast area. Expect a sunny day on Thursday with seasonable highs in the 50s and 60s outside the higher elevations. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... At 200 PM EST Monday...On Friday morning an upper trough will extend from Hudson Bay to the Gulf states. This trough progresses off the East Coast by Saturday, while an upper trough reaches the MS River Valley. The pattern deamplifies by Sunday, with broad low amplitude upper ridging over the Great Plains, and troughs off the East and West Coasts. The ridge progresses to the Great lakes and Gulf States by Monday. At the surface, on Friday morning a surface ridge will be crossing the MS River Valley. Limited NW flow moisture will be over the Southern Appalachians, but does not appear to be sufficient for snowfall production. The surface ridge reaches the Carolinas and Georgia by Saturday. The ridge moves off the East Coast on Sunday, while moisture from the Gulf of Mexico spreads north to the Southern Appalachians. Precipitation chances remain limited over our area until Monday, when better moisture arrives. Temperatures will cool from slightly above normal to slightly below normal as cool high pressure arrives, then will warm to well above normal on the back side of the surface high and rising heights aloft. && .AVIATION /03Z TUESDAY THROUGH SATURDAY/... At KCLT...VFR through the end of operations this evening. Light returns seen on radar will probably not reach the ground. A mid-level cloud ceiling will lower through the evening as moisture deepens on a SW flow aloft. Sfc wind should be light, initially from the SE, but the direction could become variable by late evening. Guidance continues to indicate a lower cloud deck moving up from the S or SW late tonight. Will keep the general idea that an MVFR-level ceiling will develop around the start of morning ops. Some of the guidance suggests that some IFR stratus could be lurking nearby around daybreak, but think that will not develop unless we get more precip than expected during the early morning hours. The ceiling should eventually break up/lift during the middle part of the day, with wind coming up from the SW. Precip chances are not great enough in the afternoon to warrant a mention. Elsewhere: VFR conditions will persist through the evening hours, with gradually lowering mid level clouds becoming lower VFR stratocumulus. Cigs are expected to lower further during the overnight hours with mainly MVFR throughout. As with CLT, cannot rule out a brief IFR ceiling, especially at KAND. Winds will become light N to NE this evening, then return to SE through later Tuesday morning. Outlook: Chances for restrictions diminish somewhat Tue night into early Wed. A cold front will approach from the west late Wednesday and bring additional chances of showers and restrictions, as well as some thunderstorms. Drier conditions end the week following the fropa. Confidence Table... 03-09Z 09-15Z 15-21Z 21-00Z KCLT High 100% High 100% High 81% High 100% KGSP High 100% Med 66% High 94% High 100% KAVL High 100% High 100% High 100% High 84% KHKY High 100% High 91% Med 66% High 98% KGMU High 100% Med 66% High 92% High 96% KAND High 100% Med 73% High 98% High 84% The percentage reflects the number of guidance members agreeing with the scheduled 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 && .GSP WATCHES/WARNINGS/ADVISORIES... GA...None. NC...None. SC...None. && $$ SYNOPSIS...JMP NEAR TERM...HG/PM SHORT TERM...SW LONG TERM...JAT AVIATION...PM

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