textproduct: Greenville-Spartanburg

WHAT HAS CHANGED

Shower and thunderstorm chances have increased for early Friday across the eastern half of our forecast area.

KEY MESSAGES

1. Unseasonably warm and humid conditions are expected for the remainder of the week, with shower and thunderstorm chances increasing Wednesday and lingering through Friday.

DISCUSSION

Key message 1: Unseasonably warm and humid conditions are expected for the remainder of the week, with shower and thunderstorm chances increasing Wednesday and lingering through Friday.

The upper level pattern across the CONUS will remain amplified and not especially progressive through much of the week, with a fairly short-lived omega block persisting over the next few days out west. The center of an upper low is expected to lift from the Southern Plains to the upper MS Valley by Wednesday morning, inducing gradual height falls over the Eastern CONUS. An associated occluding/weakening frontal zone is fcst to approach our CWA from the west on Wednesday. Persistent SLY flow ahead of this feature will result in increasingly warm and humid conditions over the next couple of days, with temps expected to be at least 5 to 10 degrees above normal while sfc dewpts are expected to reach the 60s by Wed aftn. The frontal zone should have more than enough moisture along with some modest instability in place as it moves into our area Wed aftn/evening. Short-term guidance still shows fairly robust forcing, especially in the low levels as the boundary crosses the TN Valley and the Deep South Wed aftn, but this weakens as it moves into our area Wed evening. As a result, a notable gradient in PoPs and especially QPF is anticipated from west to east, with roughly 0.5 to 1.0" amounts currently fcst across our western third (with locally higher amounts on south-facing slopes), and less than 0.25" expected over the I-77 corridor. In addition, the combina- tion of fairly weak shear and modest instability along with the occlu- ding nature of the front are not favorable for an organized severe storm threat. Regardless, a few strong-to-severe storms cannot be ruled out. Locally heavy rain is possible across our western zones, especially on aforementioned south-facing slopes, with a non-zero chance of localized flash flooding Wed/Wed night.

Little temperature contrast is anticipated in the wake of the frontal zone on Thursday, so conditions are expected to remain warm and humid. Broad cyclonic flow aloft combined with terrain effects is likely to result in some sct convection Thursday aftn/evening. By Thursday night, a weakening upper low over the Southern Plains is fcst to move quickly across the SE quadrant of the CONUS, with the associated height falls bringing another cold front to our area, and possibly another round of sct convection on Friday. At this time, most of the guidance has better coverage/higher PoPs over our eastern zones. Saturday should be mostly dry with temperatures remaining above normal and some amount of cooler/ drier air advecting into our area. By Sunday, temperatures and humidity levels should return to near-normal for early Nov.

AVIATION /19Z TUESDAY THROUGH SUNDAY/

At KCLT and elsewhere: Sct to bkn MVFR clouds continue to make their way northward over most of our fcst area early this afternoon. As such, I kept TEMPOs for MVFR cigs at the Upstate terminals and KAVL for the first few hrs of the period. By mid-afternoon, I expect the lower clouds to sct out. A deeper surge of moisture moves into the region tonight ahead of an advancing cold frontal boundary. This is expected to produce a more widespread deck of low stratus with wide- spread MVFR cigs anticipated along with periods of IFR cigs. The IFR cigs were mostly handled with TEMPOs in the 10 to 14z window. Shower chances begin to ramp up towards the end of the TAF period, with VCSH carried at the Upstate sites and a PROB30 for -SHRA at KAVL beginning earlier tomorrow. Otherwise, winds will be generally be out of the E to ENE today and tonight becoming more light and VRB overnight. Winds will eventually pick up out of the SE tomorrow afternoon with speeds of 5 to 10 kts.

Outlook: Showers and associated flight restrictions are expected to continue late Wednesday into Thursday as a front crosses the region. Additional showers and restrictions are possible on Friday, with VFR conditions returning for the weekend.

GSP WATCHES/WARNINGS/ADVISORIES

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