Sunrise 6:13 AM   Sunset 8:25 PM Moonrise 4:51 PM   Moonset 3:24 AM

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FXUS62 KGSP 201054 AFDGSP

Area Forecast Discussion National Weather Service Greenville-Spartanburg SC 654 AM EDT Mon May 20 2024

SYNOPSIS
Warm high pressure will persist across the region through the middle of the week. A cold front approaches from the northwest on Thursday, bringing a chance of showers and storms mainly to the mountains. The front will stall over the area Friday, keeping rain chances through weekend.

NEAR TERM /THROUGH TONIGHT/
As of 645 AM: Weak sfc high beginning to shift into NC from the north, supported by positively tilted upper ridge. Dense mountain valley fog and low stratus expected to linger thru 9-10 AM, with less impactful and variable fog occurring near the Piedmont rivers likely dissipating somewhat sooner. Touched up temp trends this morning, and sky cover thru the day. Beyond that, fcst appears on track.

Flow will veer to SE as sfc high builds slightly further south and east. Max temps will rebound back to normal or even a couple degrees above. Some cumulus will break out beneath the weak inversion across the area. Despite that, most prog soundings over the mountains depict some skinny CAPE developing, perhaps a few hundred J/kg. With upslope flow some convection is expected to fire there. Tame PWATs of generally an inch or less, mostly via low to midlevel moisture. Profiles are quite dry above 700 mb. Dry air entrainment will keep coverage isolated or widely scattered at best. Not particularly concerned for severe wx or for flash flood threat, but will point out any cells will be slow-moving and fairly healthy accums still may be seen. This activity will wane diurnally. SE flow will result in some areas of cloud cover persisting near the Blue Ridge Escarpment, similar to what we're seeing this morning, and with dewpoints not expected to mix out much this aftn. Mins near normal.

SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/
As of 300 AM EDT Monday: An upper ridge axis extending from the Gulf of Mexico northeast along the Appalachians will keep the atmosphere rather suppressed atop the forecast area thru the short term. Isolated showers and perhaps a couple of garden-variety tstms may develop along the ridgetops with strong daytime heating. But otherwise, just some fair wx cu and temps continuing a warming trend. Highs will be in the mid 80s on Tuesday and mid to upper 80s Wednesday across the lower mountain valleys and the Piedmont. Lows will be mainly in the 50s in the mountains and lower to mid 60s elsewhere.

LONG TERM /THURSDAY THROUGH SUNDAY/
As of 315 AM EDT Monday: Thursday has the potential to be the hottest day of the week with highs approaching 90 degrees in parts of the lower Piedmont. However, convective debris clouds may spill over the area from the west, as upper flow begins to flatten out, and this may limit insolation. While shortwave energy works to flatten the eastern CONUS ridge, guidance still is in disagreement on how far east an approaching cold front will get to our area. The ECMWF continues to keep Thursday dry, while the NBM PoPs suggest at least scattered diurnal convection returns to the mountains and possibly the I-40 corridor east. The front should sag into the area Friday, as a more pronounced wave rides thru the upper flow across the region. This should provide for better diurnal convective coverage Friday, with more shear and instability for a few strong storms. Then the front basically stalls out across the Southeast, as it becomes oriented parallel to the upper flow. So above climo PoPs looks on tap for the weekend with temps remaining a few degrees above normal.

AVIATION /12Z MONDAY THROUGH FRIDAY/
At KCLT and elsewhere: Mountain valley fog/stratus will last thru 13-14z at KAVL. Patchy/variable fog also being reported in parts of the Piedmont, mainly near rivers, but this likely will lift/dissipate in the first hr of the TAF period. NE winds will continue until early afternoon owing to weak high pressure to our north, with diurnal cu forming at MVFR to low VFR level but probably not causing cigs. Winds go SE with aftn mixing and southward migration of sfc high. Ridgetop SHRA or even TSRA are possible but too isolated to mention at KAVL. SE flow tonight will produce VFR to MVFR stratus in the foothills. KAVL likely to see valley fog develop again hence prevailing IFR mention after 07z. River valley fog appears possible, most likely affecting KHKY which gets MVFR late.

Outlook: High pressure remains dominant over our area thru Wed, but isolated mountaintop convection still expected each afternoon. Precip and restrictions possible with next front arriving late Thu or Fri.

GSP WATCHES/WARNINGS/ADVISORIES
GA...None.
NC...None.
SC...None.

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