Area Forecast Discussion
Issued by NWS Greer, SC

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000 FXUS62 KGSP 191454 AFDGSP Area Forecast Discussion National Weather Service Greenville-Spartanburg SC 1054 AM EDT Thu May 19 2022 .SYNOPSIS... Afternoon temperatures will remain well above normal through the weekend. Scattered showers and thunderstorms are expected today and Saturday. A cold front approaching the area Sunday and Monday will bring better chances for showers and storms, with cooler weather returning Tuesday. && .NEAR TERM /THROUGH TONIGHT/...
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As of 1050 AM EDT Thursday: Morning convection has moved east leaving a PPINE radar scope at this time. Big question today remains the potential for diurnal convection. Previous CAMs all had some version of convection forming over the mountains or E TN associated with a shortwave or MCV then tracking E or SE across the forecast area. All of them had at least some convection for much of the area, and all had the least chance over NE GA. The 12z HRRR has gone almost completely dry save for possibly an isolated NW Piedmont cell. The 12Z RAP shows some weak convection over NC early afternoon then dry. 12Z ARW and Fv3 still show mountain convection spreading across NC and far eastern Upstate, but a later start than usual. 12Z RAOBs show quite a bit of elevated instability with steep mid level lapse rates. The soundings and mesoanalysis show CIN needs to be overcome, but given the strong warming taking place, this should occur, but is likely helping with the later start time. Moderate effective shear is also seen in the soundings and analysis. Therefore, storms that do form have the potential for organization and producing large hail and damaging winds, but trends do show more of an NC and eastern Upstate threat. There is some mountain wave cirrus this morning which could keep highs from reaching the full sun potential. Still given the warm start and late convective initiation, hot temps look likely. Therefore, have bumped up highs a degree or so making 90s outside of the mountains likely. Upper-level ridging builds into the Southeast tonight into daybreak Friday leading to drier conditions. Lows tonight should be around 8 to 10 degrees above climo.
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&& .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
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As of 100 AM Thu: Friday does still look like the warmest day of the period, as upper ridge begins to build over the East Coast and exceptionally warm air spreads across our region on southwest flow. 850mb temps invof 20C are near daily records. A capping inversion probably will preclude any diurnal convection. Certainly seems appropriate to expect max temps will at least flirt with the record; our usual first guess, the NBM, has proven to be a little too warm in recent days, but given the strength of the low-level ridge we feel comfortable saying records may be in jeopardy. A shortwave will cross the Rockies and High Plains Saturday, subsequently leading to Great Lakes cyclogenesis. The associated cold front will reach the lower to mid Mississippi Valley Saturday night. However, over our area, the ridge will just continue to build during the same timeframe, although with the axis already being off the Atlantic coast. A plume of mosture should advect northward into the area during the day Saturday, introducing a bit of midlevel cloud cover and increasing dewpoints. Slightly cooler air also arrives in the midlevels, weakening or eroding the inversion. Accordingly a seasonable chance for diurnal convection returns to the forecast Saturday. Most guidance also suggests slightly cooler max temps; records are higher that day anyway. In short, prog soundings look typical for late spring, in terms of CCLs, lapse rates, and fairly weak shear; a seasonable risk thus will exist for isolated wet microbursts with marginally severe wind/hail.
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&& .LONG TERM /SUNDAY THROUGH WEDNESDAY/... As of 200 AM Thu: Western Atlantic ridge will hold strong into early next week. Low pressure and attendant shortwave will be shunted off to the north Sunday into Monday, and accordingly the trailing cold front will pivot or take on a more zonal orientation in that timeframe. Global models have trended later in depicting its arrival into our area, such that the front probably won`t actually arrive Sunday as once suggested. PoPs have been lowered a bit Sunday, although chances still will be higher than Saturday via prefrontal convergence and slightly lower heights. Sfc front will lay over across the Mid-Atlantic region Monday as high centers to our north; front then looks to stall as cyclogenesis occurs in the south-central CONUS. Global models show some spread in the location thereof, and thus also disagree as to where the front actually stalls. Operational GFS and a number of GEFS/GEPS members suggest the front may actually settle as far south as GA/SC, and some of the area may actually have a chance to dry out for a time. Most solutions show the front remains in our general vicinity, such that a small continuing PoP will be warranted, still with diurnal enhancement. Likely PoPs are warranted again Monday with the arrival of the front, but only peak at chance Tuesday and Wednesday. Temps probably will remain above-normal for part of the area into Monday, but most guidance does show below-normal temps Tuesday, probably via weak CAD. && .AVIATION /15Z THURSDAY THROUGH MONDAY/...
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At KCLT and elsewhere: Winds will be mainly W/WNW`ly at KAVL with SW`ly/WSW`ly elsewhere today. Should be mostly VFR through the 12Z TAF period with afternoon cumulus expected. However, we could see another round of showers and thunderstorms develop this afternoon into this evening so have TEMPOs for TSRA at all TAF sites, with the exception of KAND, to account for potential convection. Confidence is low regarding TSRA development today as model guidance is not in good agreement regarding the exact coverage of TSRA or where TSRA will initiate. Convection should wind down early evening leading to drier conditions tonight into Friday. Winds this evening into tonight will be generally SW`ly with some locations seeing light and variable winds. Outlook: Brief drying returns Friday leading to VFR conditions. Summer-like pattern returns Saturday with a chance of diurnal convection and nocturnal fog/stratus possible, especially where rain has fallen. A cold front moves into the area on Sunday with more widespread convection likely.
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&& .CLIMATE... RECORDS FOR 05-19 MAX TEMPERATURE MIN TEMPERATURE STATION HIGH LOW HIGH LOW ------- ---------- ---------- ---------- ---------- KAVL 93 1996 55 1894 65 2017 33 1894 2015 KCLT 95 1962 59 2003 71 1930 40 2009 1896 KGSP 99 1962 55 1932 68 2000 38 1976 1987 1930 RECORDS FOR 05-20 MAX TEMPERATURE MIN TEMPERATURE STATION HIGH LOW HIGH LOW ------- ---------- ---------- ---------- ---------- KAVL 91 1941 50 1894 64 2018 36 2002 1959 KCLT 95 1964 51 1981 71 1938 40 2002 1896 KGSP 96 1962 57 1981 69 1927 41 1894 RECORDS FOR 05-21 MAX TEMPERATURE MIN TEMPERATURE STATION HIGH LOW HIGH LOW ------- ---------- ---------- ---------- ---------- KAVL 93 1941 57 1993 64 2001 36 1993 1894 KCLT 97 1941 57 1888 71 1998 41 1894 KGSP 96 1941 56 1888 68 2001 40 1993 1927 && .GSP WATCHES/WARNINGS/ADVISORIES... GA...None. NC...None. SC...None. && $$ SYNOPSIS...Wimberley NEAR TERM...AP/RWH SHORT TERM...Wimberley LONG TERM...Wimberley AVIATION...AP/RWH CLIMATE...

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