textproduct: Columbia

WHAT HAS CHANGED

The forecast remains on track for showers and thunderstorms overnight and again Friday morning. Aviation discussion updated for the 00z TAF issuance.

KEY MESSAGES

- 1. Thunderstorms expected Friday morning, damaging winds are possible but overall the severe weather threat is low.

DISCUSSION

Key Message 1: Thunderstorms expected Friday morning, damaging winds are possible but overall the severe weather threat is low.

An upper level trough is digging into the central US and will move across the Southeast on Friday. At the surface, a slow moving cold front is draped across the Deep South, west of the forecast area. The upper trough will help push the front further east tonight eventually moving through the forecast area on Friday. Divergence aloft and convergence ahead of the front will increase convective activity late tonight through early Friday.

We expect a few thunderstorms tonight with weak elevated instability in place but thunderstorm chances will pick up before sunrise Friday as the upper trough approaches, enhancing convection. The threat of severe weather is low due to poor low level lapse rates but early Friday morning the wind field strengthens helping to erode the nocturnal inversion. If convection can become surface based then there is potential for a couple of stronger storms to produce damaging winds or possibly a weak tornado. REFS mean SBCAPE values range from 250 to 750 J/kg Friday morning with 0 to 6 km shear around 30 kts, and 0 to 1 km SRH around 50 m2/s2. While not overly favorable for severe weather, some organized convection could develop. The greater threat will likely be in the Pee Dee and northeast of the forecast area where daytime heating will improve low level lapse rates prior to the frontal passage. Mean QPF from the NBM and REFS still generally show 0.25 to 0.5 inches with localized higher amounts of around 1 inch in the PMM where thunderstorms develop.

Convection will push east of the area by midday or so as the front moves through. Dry, cool air then filters into the area Friday afternoon and remains in place through the weekend. Beyond that dry weather and seasonable temperatures are favored.

AVIATION /00Z FRIDAY THROUGH TUESDAY/

VFR to start off this evening, then restrictions expected to develop later tonight and through Friday morning.

Regional radars indicate a few showers are moving through the region this evening, and should at least near several taf sites over the next few hours. Initial rainfall will be light, and vfr conditions still expected with this leading batch of isolated showers. Better chance for rainfall will occur after 06z when even more moisture/forcing will approach the area. Guidance continues to show scattered to more widespread showers developing across eastern Georgia and moving through the sites as Friday morning goes along. Majority of the activity should remain showers, but a few rumbles of thunder can not be ruled out overnight. Generally continued with a VCTS group with a TEMPO for moderate rain across all sites tonight. As this occurs, the increasing low-level moisture across the area is likely to yield at least MVFR ceilings. IFR cigs are possible but this isn't really a setup that yields persistent IFR cigs across a broad area. The front is likely to push through between 12z and 18z tomorrow, yielding a return to VFR by tomorrow afternoon and evening.

EXTENDED AVIATION OUTLOOK...Aviation Conditions should improve over the weekend as dry air filters into the area.

CAE WATCHES/WARNINGS/ADVISORIES

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