Area Forecast Discussion
Issued by NWS Greer, SC

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000 FXUS62 KGSP 261757 AFDGSP Area Forecast Discussion National Weather Service Greenville-Spartanburg SC 1257 PM EST Fri Feb 26 2021 .SYNOPSIS...
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A front will remain stalled south of the region into Saturday as high pressure remains to the north. Gulf moisture will continue flowing north over the front through tonight. The boundary will retreat northward as a warm front through Sunday, with warmer temperatures gradually returning. Another cold front will cross the area from the northwest Sunday night through Monday with abundant moisture. Brief drying is expected Monday night into Tuesday before unsettled weather likely returns to the region through the middle of the week.
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&& .NEAR TERM /THROUGH TONIGHT/... As of 935 AM Friday...sct to numerous light showers have spread over roughly the western third of our CWFA over the past few hours with the heavier showers still to our west. Still expecting the sfc ridge to build in as the day progresses and keep temps from warming little from what they currently are. Otherwise, the increasing dynamical lift will combine with mech lift over the srn NC mtns and produce decent rainfall rates with rainfall amts adding up to arnd 2.0 inches in localized areas by late this evening...and this could create some minor hydro issues in this area. The WPC still has the area in a marginal risk for excessive rainfall, which seems okay at least for the srn NC mtns and srn BR. Elsewhere, rainfall amts will generally remain under an inch thru tonight, with the srn most zones likely only receiving a half inch or less of rainfall. Temps will fall during the day as a cold cP airmass works in from the NE and high temps will be reached arnd daybreak, then drop into the upper 30s to lower 40s by the afternoon. The latest NAM is still more certain of an ice event across the far nrn NC mtns, mainly Avery county this afternoon, as noted by it/s quite cold partial thicknesses. The GFS on the other hand has a cold partial thickness trof in the same area as well, yet sigfnt/ly warmer. Thus, have blended the thermal profiles of these two models and ran a top down approach for wintry precip. This gave a couple tenths of ice accum across the higher elevs of Avery arnd Beech Mtn, which makes sense given the amt of precip expected in that area between 18z-00z. So, the winter weather advisory will be continued for more of a -fzra concern with this package. Temps tonight will also be non/diurnal as the wedge breaks down and a strong warm nose aloft lowers to the sfc. Temps shud start rising after midnight, but only a couple degrees leading to readings arnd 40 F most areas by daybreak Sat. && .SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... As of 230 am EST Friday: Deep-layer southwesterly flow will set up over the region by Saturday between a trough digging through the Rockies to the west and a shallow ridge axis over the Atlantic to the east. The lingering surface wedge boundary should retreat northward through the day on Saturday, with modest rain shower chances the best over the NC mountains and north of I-40. The southwesterly upper flow will persist through weekend, and the deeper moisture and forcing will continue to wrap mainly west and north of the forecast area through much of the weekend ahead of an approaching cold front. Lingering low-level moisture and occasional upglide will likely lead to more cloudiness than not through the weekend, but with thicknesses steadily climbing and maxes reaching the upper 60s in the mountain valleys to lower or even middle 70s east of the mountains Sunday afternoon. Much deeper moisture along the frontal boundary sagging southeast will arrive on Sunday night. Heavy rainfall could occur at times, especially in the southern NC mountains, where a few nighttime rumbles of thunder will be possible as well. && .LONG TERM /MONDAY THROUGH FRIDAY/... As of 230 am EST Friday: Progressive northern tier energy will brush the region Monday through Monday night, while a closed southern stream system remains much slower to move east from the Four Corners region to north Texas. Ahead of the northern stream forcing, a cold front and associated moisture will cross the region early Monday and settle southeast of the area Monday night. Mainly morning PoPs will pare away from the northwest by late Monday, but with uncertain clearing of the southern tier Monday night depending on the boundary`s progress. 1030+ mb surface high pressure will then build from the Midwest to the mid-Atlantic coast Monday night through Tuesday, spilling chilly thicknesses down across the region and producing temperatures a couple of categories below climo in most areas by Tuesday afternoon. The southern stream system should open up and then reach the southern Appalachians by Tuesday night, with a return of briefly deeper moisture. The main question centers around how quickly upglide moisture returns ahead of this wave, with PoPs increasing through Tuesday, but with maximum PoP values more likely Tuesday night. Brief ptype issues will be possible in the NC mountains depending on the precipitation timing. Model solutions then become out of phase Wednesday through Thursday, with the ECMWF featuring a central CONUS trough while the GFS indicates a shallow ridge axis moving east. However, sensible weather differences are actually not that stark despite these differences given a westerly component to the low-level flow and somewhat limited moisture. So, will feature mainly low end chance PoPs for now on Wednesday and Thursday with temperatures rebounding to near, or slightly above, climatology. && .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
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At KCLT and elsewhere: High pressure ridging in from the NE will interact with a moist frontal boundary and bring sct to numerous showers across the fcst area thru Saturday morning. Still expect cigs to deteriorate to IFR and possibly LIFR later this evening and persist thru the morning. Periods of heavier rain and lower visby associated with passing upper energy will cross the fcst area from the west, however confidence is lower wrt timing and duration of the lower visby at most sites. Conditions should improve to MVFR by late morning/early aftn tomorrow as showers fizzle out. As is typical in a wedge pattern, winds outside the mtn valleys will remain NELY thru early tomorrow and eventually revert back to a SWLY direction by the end of the period 18z tomorrow. At KAVL, winds will favor a SLY to SELY direction thru the taf period, with a period of low-level wind shear (on the order of 35 kts or so) expected early tomorrow morning. Outlook: Sct to numerous showers and associated flight restrictions are expected to persist thru the weekend and into early next week, with drying expected on Tuesday. Confidence Table... 18-24Z 00-06Z 06-12Z 12-18Z KCLT Med 74% Med 76% Low 59% Med 75% KGSP Med 65% Med 65% Med 66% High 83% KAVL High 81% High 90% Med 69% Med 73% KHKY High 85% Med 64% Low 58% Med 77% KGMU Med 60% Med 65% Low 54% Med 79% KAND Med 65% Med 60% Med 66% High 84% 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:
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&& .GSP WATCHES/WARNINGS/ADVISORIES... GA...None. NC...Winter Weather Advisory until 10 PM EST this evening for NCZ033. SC...None. && $$ SYNOPSIS...HG NEAR TERM...JPT/SBK SHORT TERM...HG LONG TERM...HG AVIATION...JPT is the U.S. government's official web portal to all federal, state and local government web resources and services.