textproduct: Greenville-Spartanburg

WHAT HAS CHANGED

Hotter and more humid conditions on Monday.

KEY MESSAGES

1. Showers and thunderstorms through this evening, some with heavy rainfall. 2. Mainly diurnal convection expected into early next week. Warming through Friday then slowly back to near normal.

DISCUSSION

Key message 1: Showers and thunderstorms through this evening, some with heavy rainfall.

A sharp trough will move into the area today and east of the area tonight. At the surface, a weak backdoor front stalls over the area then washes out. Copious amounts of deep moisture and weak instability will create the conditions for increasing chances of showers and thunderstorms across most of the forecast area. Guidance has backed off on the early onset of storms, but they do show showers generally west of I-26 through the morning. Better storm chances begin early in the afternoon then diminish through the evening. High PW values and slow moving storms will lead to some heavy rainfall, mainly over the western portions of the forecast area. Isolated flooding will be possible where training of cells occur or upslope flow is maximized. Severe storm chances look minimal but not zero. Morning clouds and showers will keep highs up to 5 degrees below normal for most and near normal for the CLT Metro. Convection tapers off early in the evening.

Key message 2: Mainly diurnal convection expected into early next week. Warming through Friday then slowly back to near normal.

Weak ridging returns Wednesday into Friday. A series of shortwaves bring nearly zonal flow for the weekend and maybe a weak trough by Monday. At the surface, high pressure to our east keeps an moist, unstable airmass over the area through Friday. This leads to continued chances of mainly diurnal convection. The guidance shows a cold front moving toward the area Saturday. They differ on whether the front stalls to our west or moves into or through the area. The guidance blend does show diminishing convective chances for the weekend, but chances ramp back up early next week as a moist southerly flow returns.

A warming trend takes place through Friday with the model blend now showing hot and humid conditions on Friday. Highs in the mid 90s for many outside of the mountains, leading to heat index values around 100 for many outside of the mountains. Would like to see some continuity in the guidance to increase confidence in this as the guidance a few days ago showed this then recently backed off on the potential. A slow cooling trend then takes place with highs dropping back to near normal by Monday.

AVIATION /07Z TUESDAY THROUGH SATURDAY/

At KCLT and elsewhere: Tricky forecast this evening as guidance has been too aggressive with cig restrictions. Guidance generally suggests cigs will drop to MVFR or even IFR by daybreak, but some have backed off completely. Have followed the slower trend, but still have all but KAVL, KGSP, and KGMU falling to IFR, with MVFR there. MVFR fog at some locations as well. Cigs lift to low VFR by noon or so. CAM guidance also has slowed the onset of convection this morning. Some do still show morning showers, so have VCSH then, but have backed off on TSRA until early to mid afternoon in PROB30s. VFR expected into the evening. MVFR cigs and vsby may redevelop overnight. Light S to SE wind overnight picks up from the S to SW during the day, going back to light overnight. KHKY the exception with NE wind through much of the day with SW for late afternoon into the evening.

Outlook: Diurnal convection and associated restrictions are expected into the weekend. Mtn valley fog and low stratus are possible each morning.

GSP WATCHES/WARNINGS/ADVISORIES

GA...None. NC...None. SC...None.