Area Forecast Discussion
Issued by NWS Greer, SC

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000 FXUS62 KGSP 081337 AFDGSP Area Forecast Discussion National Weather Service Greenville-Spartanburg SC 937 AM EDT Sat Aug 8 2020 .SYNOPSIS... A return to more typical isolated to scattered summertime thunderstorm activity is expected over the weekend as modest drying arrives from the west. Deeper moisture will gradually return early next week and support a more active pattern from Tuesday onward. && .NEAR TERM /THROUGH TONIGHT/... As of 935 AM: Minor adjustments made to temperatures/sky to coincide with latest trends as the rest of the near term forecast remains on track. Latest satellite imagery continues to show lingering patchy fog (dense in some of the mountain valleys) and low stratus this morning, but overall conditions are improving faster than we`ve seen the past few days. Current temperatures are in the low to mid 70s. Previous discussion: A short wave trough will continue to progress across the northeast quadrant of the country through the morning, and drier low level air will try to filter into the Eastern Seaboard in its wake. As such, guidance is a bit stingier with instability across the forecast area this afternoon in comparison with recent days, but nevertheless still adequate to support deep convection. Meanwhile, short term guidance is in good agreement in migrating a weak short wave trough across the forecast area throughout the day. All told, conditions should be favorable for diurnal convective initiation, although coverage should be a bit less than what one would usually expect for mid-summer, generally 20 to 40% across the mtns, and 20% or less east. With less in the way of low clouds expected across the area this afternoon, max temps are forecast to be right around normal. Convection should diminish quickly this evening, giving way to a seasonably warm and muggy night. && .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... As of 305 AM EDT Saturday: the short-term fcst picks up at 12z on Sunday with weak, WLY flow aloft and broad upper ridging in place across the region. Little change is expected wrt the upper-level pattern thru the period, as broad upper ridging persists across most of the CONUS and weak, embedded upper shortwave energy gradually ripples eastward over the region. At the sfc, the deeper moisture and higher PWAT values are expected to remain displaced off to our east over the weekend as the weak upper trof axis translates east and fills in. On Monday, some degree of moistening is likely as return flow from the gulf gradually increases thru the day and profiles become more conducive for convection. Overall, no significant changes were made to the sensible fcst. Like Saturday, Sunday will see below climo PoPs with values increasing to near climo for Monday aftn/evening. Temps should be a few degrees above climo on Sunday and Monday, but with dewpts expected to mix out (at least to some degree) each day, Heat Indices should remain below 100 degrees for all but our southern-most zones. && .LONG TERM /TUESDAY THROUGH FRIDAY/... As of 245 AM EDT Saturday: the extended fcst picks up at 12z on Tuesday with weak flow aloft and extensive upper ridging spread across most of the CONUS. The upper-lvl pattern is not expected to change much thru the period, with the polar jet remaining well to the north and over Canada while upper ridging persists across most of the CONUS. The sfc pattern will remain fairly messy thru the period as well, with the Bermuda High keeping generally moist, SLY flow over the southeast. On Tuesday, a weak cold front approaches the fcst area from the NW, but appears to stall out as it lays north of the CWFA early Wednesday. As it does, a weak lee trof appears to develop on Wednesday as moisture begins to pool over the region. This pattern will likely continue for the rest of the period as improving SLY flow brings a resurgence of gulf moisture over the region for Thursday and beyond. Overall, there were no significant changes made to the fcst with diurnally-driven, above-climo PoPs each day and temps a few degrees above normal for Tuesday and Wednesday and near normal for for Thursday and Friday. && .AVIATION /14Z SATURDAY THROUGH WEDNESDAY/... At KCLT and Elsewhere: IFR or low MVFR cigs have developed at KCLT and the upstate SC terminals, while LIFR or VLIFR conditions persist at KAVL and KHKY. These conditions are expected to persist until late morning, with all indications pointing toward a quicker improvement in conditions than we`ve seen the past couple of mornings. Otherwise, while convection is forecast to develop across the area again this afternoon/evening, coverage is expected to be somewhat limited...generally widely scattered across the mountains, and isolated across the Piedmont and foothills. As such, Prob30s for TSRA during the late afternoon/evening only appear warranted at KAVL at this time. Overnight/early morning Sunday restrictions should be confined to mountain valley fog/low stratus, with 4SM/SCT004 forecast at KAVL, although conditions could prove to be quite similar to this morning at that site. Outlook: Coverage of diurnal convection is expected to remain somewhat sparse through Monday, but will begin to increase again by mid-week. Morning fog/stratus restrictions will also be possible each morning, especially over the usual mountain valleys. Confidence Table... 13-19Z 19-01Z 01-07Z 07-12Z KCLT High 85% High 100% High 100% High 100% KGSP High 92% High 100% High 100% High 100% KAVL Med 76% High 100% High 95% Low 59% KHKY High 80% High 100% High 95% High 89% KGMU High 90% High 100% High 100% High 100% KAND High 90% High 100% High 100% High 100% The percentage reflects the number of guidance members agreeing with the scheduled TAF issuance flight rule category. Complete hourly experimental aviation forecast consistency tables are available at the following link: www.weather.gov/gsp/aviation && .GSP WATCHES/WARNINGS/ADVISORIES... GA...None. NC...None. SC...None. && $$ SYNOPSIS...JPT NEAR TERM...JDL/12 SHORT TERM...JPT LONG TERM...JPT AVIATION...JDL

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