Area Forecast Discussion
Issued by NWS Greer, SC

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000 FXUS62 KGSP 032046 AFDGSP Area Forecast Discussion National Weather Service Greenville-Spartanburg SC 446 PM EDT Fri Apr 3 2020 .SYNOPSIS... High pressure slowly builds into the region through Saturday, then shifts to our east on Sunday. A weak cold front will push in from the northwest by Sunday evening, stalling over the area Monday, before lifting back north as a warm front on Tuesday. A stronger cold front will cross the region on Wednesday. && .NEAR TERM /THROUGH SATURDAY/... As of 440 pm Friday: The current forecast remains on track as a flattening short wave ridge moves east from the Miss Valley/Great Lakes region late this afternoon, and likely across the Appalachians by the end of the period. The only minor adjustment will be to add a touch more clouds earlier in the near term as 700 to 500 mb layer moisture moves southeast across the southern Appalachians, along with weak 500 mb embedded vorticity lobes surviving the ridge axis. Otherwise, slackening winds and a dry boundary layer will allow tonight`s min temps to cool to just a couple of degrees above climo, moderated a bit by the increasing clouds. Tomorrow`s maxes should again be a solid 5 degrees warmer than normal. Dewpoints creeping into the 30s are expected to result in improving RH profiles Saturday. See the Fire Wx discussion below for details. && .SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/... As of 215 PM EDT Friday: The short term will be dominated by a broad 500 mb ridge that will build somewhat across the eastern 2/3rd of the CONUS. At the sfc, a dying cold front will approach the Southern Appalachians from the Ohio Valley Sunday aftn, with the latest guidance not too impressed with QPF response. There may be just enough moisture to support isolated to widely scattered showers in the mountains. If you throw out the GFS, the Piedmont looks dry. The front stalls out across NC in an east-west orientation, as a modest high pressure center enters the Northeast. The front actually gets a little stronger on Monday thanks to some frontogenesis, and should trigger scattered showers across the NC zones, with isolated coverage to the south. Sbcape of 500+ J/kg may be enough for some tstms, but given lack of strong forcing, the severe threat should remain low despite 35-40 kt of 0-6 km bulk shear. Temps will continue a warming trend with the building upper ridge. Highs about 5-10 deg above normal, lows 10-15 deg above normal. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... As of 245 PM EDT Friday: a couple of impulses diving out of southern Canada will work to flatten the eastern CONUS upper ridge Tuesday thru Wednesday, with the second wave becoming a large vortex over the Great Lakes by Thursday. Meanwhile, a large closed low over California will slowly wobble east Wednesday thru Thursday. The medium range guidance are completely all over the place with when this low gets picked up by the northern stream and ejects east of the Rockies. The GFS is the usual fast guidance opening it up by 12z Friday, while the Canadian holds on to it thru the weekend. The first wave that will drop into the Great Lakes will push a cold front across the forecast area Wednesday. But behind that, confidence in the forecast really goes down. I expect temps to trend cooler, back to near normal by next Friday. Precip will be mainly confined to the mountains, highest on Tuesday and Wednesday (mainly chc mountains and slgt chc east), then slgt chc or less Thursday and Friday. && .AVIATION /21Z FRIDAY THROUGH WEDNESDAY/... At KCLT and elsewhere: VFR will persist through the period, with only occasional mid/high level clouds continuing. Winds will generally be NW @ 5-10 kts at the western NC terminals late this afternoon, although a lee trough may cause periods of variable directions at KHKY. Winds may be light SW for partof the late afternoon at the Upstate SC terminals. Winds become light/vrbl at all sites this evening, and light N to NE through Saturday. Outlook: Expect VFR conditions to persist into early next week. Flight restrictions may return on Tuesday as moisture increases ahead of a weak front. Confidence Table... 20-02Z 02-08Z 08-14Z 14-18Z 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: && .FIRE WEATHER... Widespread dewpoints in the 20s to lower 30s is (or eventually will) result in RH bottoming out in the 15-25% range across much of the forecast area this afternoon. After coordination with NWS KFFC, a Fire Danger Statement will be issued for our GA counties into the early evening hours. Winds generally remain in the 5-10 mph range, although some gusts of 15-20 kts are possible, especially across western NC. A Fire Danger Statement remains in effect for Upstate SC (The SCFC has since opted to issue a "Red Flag Fire Alert" for the entire state. We usually let that speak for itself, but since the FDS has already been issued, we`ll let it ride out to avoid confusion.) A FDS also remains in effect for the NC Piedmont this afternoon. Weaker winds as well as increasing dewpoints (yielding min RH in the 25-35% range) are expected Saturday, thus no additional products are expected at this time. && .GSP WATCHES/WARNINGS/ADVISORIES... GA...Fire Danger Statement until 8 PM EDT this evening for GAZ010- 017-018-026-028-029. NC...Fire Danger Statement until 8 PM EDT this evening for NCZ035>037-056-057-068>072-082-501>510. SC...Fire Danger Statement until 8 PM EDT this evening for SCZ001>014-019. Fire Danger Statement from Saturday afternoon through Saturday evening for SCZ001>014-019. && $$ SYNOPSIS...ARK NEAR TERM...HG/JDL SHORT TERM...ARK LONG TERM...ARK AVIATION...HG/JDL FIRE WEATHER...JDL is the U.S. government's official web portal to all federal, state and local government web resources and services.