Area Forecast Discussion
Issued by NWS Greer, SC

Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS62 KGSP 251913 AFDGSP Area Forecast Discussion National Weather Service Greenville-Spartanburg SC 313 PM EDT Tue Sep 25 2018 .SYNOPSIS... A cold front will move into the mountains Wednesday and stall across the area. This front will help produce showers and thunderstorms as it lingers over the forecast area into the weekend. && .NEAR TERM /THROUGH WEDNESDAY/...
-- Changed Discussion --
As of 255 PM EDT: A weak sfc low pressure system over the Great Lakes continues to drag a neutrally tilted cold front across W portions of the Ohio River Valley S to near New Orleans. Weak southerly upglide has helped to sock in portions of the Upstate into W NC with low clouds this afternoon with highs only into the 70s so far today. Outside of this region highs have reached up to around 80 and will likely continue to climb a few degrees over the next few hours. A few showers have developed over NE Georgia. Some of these showers may push into the W Upstate of SC or W NC later this afternoon or evening despite the stabilizing effects of the remnant cool pool from the CAD. A thunderstorm or two may develop across far SW portions of the FA this afternoon or early evening due to limited instability. Partly cloudy to mostly clear skies tonight along with remnant llvl moisture will likely bring at least patchy fog to some areas east of the mtns, although likely not as widespread or restricting as early today. After a relative lull in precipitation later this evening, an approaches cold front and some increase in mid level forcing will provide increasing cloud cover and the opportunity for rain and thunderstorms from W to E late tonight and through the day Wednesday. Moderate instability and some upper level support will likely support some gusty winds and small hail with the strongest thunderstorms Wednesday afternoon and early evening. The moist environment will continue to support mild overnight lows from the 60s to near 70. High temperatures Wednesday are expected to rebound into the 80s east of the mountains where better insolation is expected to only 70s at best across most mountain locations.
-- End Changed Discussion --
&& .SHORT TERM /WEDNESDAY NIGHT THROUGH THURSDAY NIGHT/...
-- Changed Discussion --
As of 255 PM EDT Tuesday: With an upper longwave trough across much of the mid to eastern CONUS and Atlantic ridge well in place, scattered to numerous showers and thunderstorms are expected throughout the short term forecast period, which begins Wednesday night, as a cold front becomes stationary across the Carolinas. While the more favorable dynamics will stay just north of the FA on Wednesday as the shortwave moves across the Great Lakes (as highlighted in the current SPC Day 2 Convective Outlook), per latest guidance, enough available instability and low yet notable shear in place in the evening could still spark a few isolated strong to severe storms around the beginning of the forecast period. Also, would not entirely rule out heavy rainfall/localized minor flooding with any storm as PW values will near 2 inches. Into Thursday, latest guidance progs environmental conditions not as conducive for a severe threat given persistent cloud cover/slightly lower high temps and thus, less instability than on Wednesday. However, with the front stationary across the FA, a bit of a shear axis with lowered instability could still pose a threat for an isolated stronger/severe storm. Temperatures throughout the forecast period will remain just above normal.
-- End Changed Discussion --
&& .LONG TERM /FRIDAY THROUGH TUESDAY/...
-- Changed Discussion --
As of 220 PM EDT Tuesday: The cold front stalled over the area in the short term finally moves south of the area Saturday as high pressure builds in from the north. However, a moist low level flow southerly flow develops bringing moisture in over the building high pressure. This creates a cold air damming scenario which remains in place through Monday. The flow over the high isn`t that strong and there is dry air which works in from the north. Therefore, PoPs are limited to the slight chance to low chance range through the period. The air mass isn`t especially cool either, so temps remain near nor a little above normal. The center of the high moves off shore Tuesday as a front moves into the Ohio Valley. The moist low level flow continues keeping a chance of rain in the forecast. Temps will a little above normal.
-- End Changed Discussion --
&& .AVIATION /19Z TUESDAY THROUGH SUNDAY/...
-- Changed Discussion --
At KCLT and elsewhere: Low confidence in 18Z TAFs due to uncertainty in ceiling improvements early in the period and timing of TSRA and associated restrictions near the end. Low ceilings across the afternoon expected to continue to improve this afternoon, with terminals nearest the mountains likely being the slowest to improve. Remnant moisture and mainly clear skies will likely lead to mainly MVFR fog with lower restrictions possible in mtn valleys including KAVL. TSRA activity expected to gradually spread from west to east across the region between 10 and 18Z. Timing of shower and thunderstorm activity and assoc restrictions may be off by 3 hours. Outlook: A stalled front will across the region will continue to be a trigger point for showers and thunderstorms through at least Friday and possibly into this weekend. Confidence Table... 19-01Z 01-07Z 07-13Z 13-18Z KCLT High 96% High 96% High 96% High 100% KGSP High 86% High 96% Med 66% High 87% KAVL High 86% Med 74% Med 79% High 83% KHKY High 91% High 91% Med 73% High 87% KGMU High 91% High 100% High 84% High 88% KAND High 91% High 100% High 93% High 85% 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
-- End Changed Discussion --
&& .GSP WATCHES/WARNINGS/ADVISORIES... GA...None. NC...None. SC...None. && $$ SYNOPSIS...RWH NEAR TERM...Munroe SHORT TERM...SGL LONG TERM...RWH AVIATION...Munroe

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.