Area Forecast Discussion
Issued by NWS Greer, SC

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000 FXUS62 KGSP 241011 AFDGSP Area Forecast Discussion National Weather Service Greenville-Spartanburg SC 611 AM EDT Sun Sep 24 2017 .SYNOPSIS... Broad, dry high pressure will persist across the region through the middle of next week. Tropical Cyclone Maria is expected to remain off the East Coast through mid-week. A cold front will sweep across the region on Thursday, bringing drier and much cooler air to the area for week`s end. && .NEAR TERM /THROUGH TONIGHT/... As of 600 AM EDT...No sigfnt changes needed to the fcst grids. Mtn valley fg and low cigs will reamain steady state before burining off rather quickly aft 13z. A dry pattern will become even drier today as high pressure continues to ridge in from the north. This high will be stacked thru a deep layer while a strong h5 high centers across the ern Glakes. Model soundings are showing limited moisture to work with as well as deep layered sbCIN...thus supporting only fair-wx Cu and perhaps some Ci moving in from TC Maria as she advances north. PoPs have been left nil for the entire FA as weak e/ly mech lift over the higher terrain will not have enuf moisture to overcome a strong subs inversion. Max temps will again reach a few degree warmer than climo...and with a normal diurnal drop-off min temps will also be held a few degrees above normal. Some low-end gusts as possible in good momentum transfer especially across the ern zones...but overall winds will remain below 10 kts or so. Dewpoints will mix out into the L60s non/mtns as well...making for a very nice day on tap all locales. && .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... As of 330 AM Sunday: The dry and unseasonably warm weather will persist through early week, as mean, high amplitude upper ridging persists over the area. A combination of surface high pressure centered over the northeast Conus and Tropical Cyclone Maria moving N/NW toward the NC coast will support a sharp surface ridge over the area, with N->N/NE surface winds, which could become somewhat breezy by the end of the period. Although moisture may increase to some extent within the circulation around Maria, especially over the Piedmont, showers would be very unlikely considering the official forecast track during the late short term, which would suggest a subsident regime over our area. Pops will therefore be kept below slight chance through the period, while temps will remain a solid 5-ish degrees above climo. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... As of 340 AM Sunday: It still appears that a pattern change is in the offing by the end of the week, as a series of potent short wave troughs traversing the northeast quadrant of the Conus act to break down the upper ridge. An attendant frontal boundary is expected to cross the forecast area during the Thu/Thu night time frame. Persistent, mostly dry N/NE flow in advance of the frontal zone will yield very limited moisture, and fropa will most likely be of the dry variety. Only token slight chance pops will be carried across portions of the high terrain during the aforementioned time. The front will sweep Tropical Cyclone Maria away from the East Coast, before any impacts of note would occur across our area. The primary impact of the front will be to give the area the first taste of fall, as temps are forecast to be at least 5 degrees below normal and dewpoints considerably drier by Day 7. Global model guidance is depicting some degree of cyclogenesis along the remnant baroclinic zone in the vicinity of the Southeast coast next weekend (although timing/location/intensity of the cyclogenesis remains highly uncertain), so small pops are carried by the end of Saturday, mainly across the southeast third of the CWA. && .AVIATION /10Z SUNDAY THROUGH THURSDAY/... At KCLT and Elsewhere: No flight restrictions all sites except KAVL this morning. Recent precip and lingering mtn valley moisture will allow for LIFR cigs and vsby before daybreak which will dissipate thru 14z. Stacked high pressure will preclude any convec concerns with sbCIN remaining high thru a deep layer per the latest model soundings. Cu will be hard to form within drying LCLs. Winds will remain aligned generally in a ne/ly direction with some low-end gusts possible this afternoon, generally across the ern zones including KCLT. Outlook: Dry conditions expected for the first half of the week. Under mostly clear skies and calm conditions, fog and/or low stratus are likely in the mtn valleys each of the next few mornings. Confidence Table... 10-16Z 16-22Z 22-04Z 04-06Z KCLT High 100% High 100% High 100% High 100% KGSP High 100% High 100% High 100% High 100% KAVL High 80% 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 and ensemble forecasts are available at the following link: www.weather.gov/gsp/aviation && .GSP WATCHES/WARNINGS/ADVISORIES... GA...None. NC...None. SC...None. && $$ SYNOPSIS...JDL NEAR TERM...SBK SHORT TERM...JDL LONG TERM...JDL AVIATION...SBK

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