Area Forecast Discussion
Issued by NWS Greer, SC

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000 FXUS62 KGSP 070656 AFDGSP Area Forecast Discussion National Weather Service Greenville-Spartanburg SC 256 AM EDT Fri May 7 2021 .SYNOPSIS... A cold front will cross the region from the west today. Drier high pressure will return over the weekend. Another cold front will approach from the west Sunday night and then move slowly across the region Monday into early Tuesday. High pressure will set up by mid- week, but with a moist low pressure system returning from the west Wednesday night into Thursday. && .NEAR TERM /THROUGH TONIGHT/... An upper level trof will continue to cross the area thru the period. The associated low freezing levels is helping to produce small hail in a cell across Cabarrus Co and there could be periodic weak storms developing overnight as upper energy remains quite strong, altho moisture is limited. With continued upslope flow, expect -shra across the wrn NC mtns this morning lingering into the early afternoon. Also, a few -snsh are possible across elevations abv 5 Kft with limited or no accum. Expect a dry and breezy day today as an area of hipres builds across the Deep South and produces a fairly tight p/grad across the FA during max mixing. Soundings continue to indicate deep mxing up 8 Kft and winds at the top of the mixed layer will be arnd 35 kts. Don/t expect winds of that magnitude mixing to the sfc as winds decrease abt 10-15 kts toward the sfc, but with good monentum transfer due to uniform flow, winds should gust into the 25-30 mph range across most areas. Gusts approaching 40 kts over the higher NC mtn elevations are also likely and will mention winds and possible trees down in the HWO. With the deep mixing will also come low sfc td/s. Went on the low side of guidance and vertically mixed lower values thru the afternoon. Max temps will struggle a cat or so below normal in CAA flow, so afternoon RH values will be tricky. For now, believe RH levels will lower into the 25-30 percent range. A FDS is in effect for the non/mtns of NC and will likely expend this to include the SC zones and portions of NE GA. Mins tonight will drop to arnd 10 degrees below normal as colder Canadian air continues to advect into the region. && .SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... As of 300 AM EDT Friday: By the start of the short-term on Saturday morning, a broad 500mb trough is lifting out of the Mid-Atlantic as it pushes offshore, and heights over the Carolinas are rapidly rising. A stout ridge is positioned over the Central Plains and building into the eastern CONUS. At the surface, high pressure creeps into the Southeast, with the center of the high passing well south of our CWA...through south/central MS/AL/GA, from the looks of things. So, we`ll maintain steady westerly surface flow throughout Saturday, remaining mostly dry except on the northern and western fringes of the high, especially the Appalachians where upslope flow will produce some light, scattered showers as NW flow interacts with moisture associated with a developing low to the west. So, PoPs should move from west to east into the forecast area. Expecting a high a few degrees below normal owing to deep CAA associated with the continued NW flow. Saturday night, flow becomes more southerly as the high passes east of us, and so moisture advection will pick up and moisten the environment ahead of an advancing cold front Sunday night. This front looks to be on our doorstep by Sunday at daybreak, with PoPs already ramping up by then. Little chance of thunder with this system; with poor fropa timing and limited moisture, we won`t see much instability so the likely scenario is just some showers. Thanks to the reversed surface flow and decent insolation for much of the day, Sunday`s high will jump to barely above-normal. && .LONG TERM /MONDAY THROUGH THURSDAY/... As of 230 am EDT Friday: A northern stream trough will move from the Great Lakes to the East Coast Monday through Tuesday. This system will push a cold front through the region, but with somewhat limited deeper moisture along the passing frontal zone. PoPs will be fairly high in western sections Monday, but with some drying crossing the mountains and points east through Monday night. Additional downslope drying will occur on Tuesday, with PoPs limited mainly to southern tier sections as the boundary departs. Near climo temperatures on Monday will cool at least a category under cold advection on Tuesday. A flat upper ridge will transit the Appalachians Wednesday, with surface high pressure crossing the central Appalachians and building southward across the forecast area. Cool thicknesses will lead to well below climo temperatures. There is reasonably good consensus on the next digging upper wave approaching from the Mississippi Valley starting Wednesday night. Abundant deeper moisture ahead of this system will return Wednesday night and likely cross the area on Thursday. Moist upglide will keep temperatures on the cool side due to in situ cold air damming from the departing offshore surface high. Heavy rainfall will be possible for our area, depending on the position of a surface wave wrapping toward the southeast coast along the stalled wedge boundary. Instability could get uncovered from the southern tier during the afternoon hours, with elevated instability possible throughout. Will shade to higher PoPs and lower max temps given the wedge like setup Thursday. && .AVIATION /07Z FRIDAY THROUGH TUESDAY/... At KCLT and elsewhere: An upper level trof crossing the area will generate a few brief -shra and possibly some thunder this morning possibly at KAVL and east toward KCLT. Otherwise, VFR conds and expect the atmos to remain mixed overnight. Deeper mixing will develop by mid-morning and nw/ly gusts are likely in the 20-25 kt range thru the afternoon before tapering off arnd 00z, except at KAVL where low-end to moderate gusts will continue thru the period. Outlook: Predominately VFR conditions are expected thru the weekend. The next system to bring restrictions is looking like it will arrive on Monday of next week. Confidence Table... 07-13Z 13-19Z 19-01Z 01-06Z KCLT High 100% High 100% High 100% High 100% KGSP High 100% High 100% High 100% High 100% KAVL High 100% High 97% 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 && .FIRE WEATHER... Steep lapse rates underneath a passing shortwave trough will allow very good mixing this afternoon and dewpoints could drop more than most model guidance suggests. Modest flow in the mid-levels will be brought down to the surface as gusts potentially range between 25-30 mph. While fuels remain moist following recent heavy rains, the meteorological conditions are marginally conducive to elevated fire danger. Thus, in coordination with land managers a Fire Danger Statement will be issued for most areas outside the mtns. && .GSP WATCHES/WARNINGS/ADVISORIES...
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GA...None. NC...Fire Danger Statement from noon EDT today through this evening for NCZ035>037-056-057-068>072-082-501>510. SC...None.
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&& $$ SYNOPSIS...HG NEAR TERM...SBK SHORT TERM...MPR LONG TERM...HG AVIATION...SBK FIRE WEATHER...GSP

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