Area Forecast Discussion
Issued by NWS Greer, SC

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000 FXUS62 KGSP 160158 AFDGSP Area Forecast Discussion National Weather Service Greenville-Spartanburg SC 958 PM EDT Sat May 15 2021 .SYNOPSIS... It will continue to warm up through Sunday with a gradual increase in daily shower chances through Wednesday. Sprawling Bermuda high pressure will aid in the onset of summerlike conditions by the end of the upcoming work week. && .NEAR TERM /THROUGH SUNDAY/... As of 955 PM: Fcst on track. Cirrus are beginning to spread across the Appalachians, in the northwest upper flow and ahead of an approaching shortwave; some diurnally generated cu remain trapped under subsidence inversion. Even though heights rise through the period, northwest flow remains with additional weak short waves moving across the area through the flow. The center of high pressure settles over the area but a weak warm front approaches the northern mountains from the west. This could be enough for highly isolated showers across the northern mountains by morning, but based on current guidance saw fit to reduce PoP slightly there; there just isn`t much forcing to work with. The upstream radar echoes associated with the aforementioned shortwave don`t appear to be producing much at the ground, if at all, and with the wave dampening as it moves in our direction, looking unlikely we will see anything aside from perhaps a stray sprinkle tonight. Think decent radiative conditions will develop despite the high cloud cover; brought mins down another degree or two in the typically cooler areas. But with dewpoints looking a little lower, Little TN Valley fog is looking a little more patchy. Lows will be a few degrees below normal. Weak instability develops across the mountains and northern tier of the CWFA Sunday. This combined with the lingering moisture, short wave activity, warm frontal advance, and even some upper divergence will produce scattered showers over the much of the NC mountains and northern foothills. Isolated showers may develop to the south and over the NW Piedmont. Can`t rule out a rumble of thunder or two during the afternoon. Conditions are less favorable over the NC southern Piedmont, NE GA, and the bulk of the Upstate, so a dry forecast continues there. Despite the lingering clouds, rising heights and thickness values suggest highs near normal for all but the mountains where they will continue a few degrees below normal. && .SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/... As of 1210 PM EDT Saturday: It is still looking like isolated diurnally fired tstms remain possible along the I-40 corridor Monday afternoon, within the developing weak instability axis and in proximity to retreating weak wedge boundary. Across the southern half of the cwfa, further into the warm sector and higher heights, the atmosphere should remain capped as max temperatures creep to just above the mid-May climo. Despite the trend of upper ridge axis sharpening up atop the region on Tuesday, llvl baroclinic zone along with a weak llvl pattern waa exists and should be the focus for scattered diurnal deep convection, especially in the piedmont where the better llvl convergence is progged. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... As of 100 PM EDT Saturday: Upper level ridging strengthens atop the eastern seaboard to start off the period. Sensible wx should be limited to diurnally fired storms over the high terrain as the llvl flow around mid-atlantic hipres ascends the Blue Ridge. Deeper layered ridging is expected to keep the atmosphere supressed regionwide Thursday thru Saturday with a warming trend on tap, featuring solid upper 80s for piedmont max temps by the end of the period. && .AVIATION /02Z SUNDAY THROUGH THURSDAY/... At KCLT and elsewhere: VFR expected at the terminals this period. A few stratocu may be seen this evening, but the primary cloud cover will be cirrus associated with a dampening shortwave moving from KY/TN into NC. A sprinkle can`t be ruled out at KAVL or KHKY, but likely of no impact. Cirrus likely will peak in coverage in the early morning, but diurnal cu will be a bit more plentiful and lower Sunday with replenished moisture, and they predominate. Winds are a little trickier, expected to be mainly light/variable tonight though tending SW for the Piedmont sites and NW at KAVL. A shift to NW and eventually NE is suggested for KHKY/KCLT/KGSP/KGMU Sunday afternoon, with a weak boundary setting up and high pressure over the Mid-Atlantic. Outlook: VFR conditions should generally prevail into early next week, although brief restrictions in morning low stratus and/or fog will remain possible, mainly in the mountain valleys. Diurnal shower chances will increase early next week, although coverage is expected to be widely scattered at most. Confidence Table... 02-08Z 08-14Z 14-20Z 20-00Z KCLT High 100% High 100% High 100% High 100% KGSP High 100% High 100% High 100% High 100% KAVL High 100% High 100% High 100% High 100% KHKY High 100% High 100% High 100% High 100% KGMU High 100% High 100% High 100% High 100% KAND High 100% 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...CSH NEAR TERM...RWH/Wimberley SHORT TERM...CSH LONG TERM...CSH AVIATION...Wimberley

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