textproduct: Columbia

WHAT HAS CHANGED

Updates to Key Messages. Aviation discussion updated for 12z TAFs.

KEY MESSAGES

- 1. Some areas of fog this morning. Cooler temps into mid- week. Warming and wetter pattern develops into the weekend.

DISCUSSION

Key Message 1: Some areas of fog this morning. Cooler temps into mid-week. Warming and wetter pattern develops into the weekend.

Clearing skies, light winds, and lingering low-level moisture have allows some areas of fog to form across the Midlands and CSRA this morning. Some visibilities below 1 mile will be encountered, but this should not be widespread enough for any Dense Fog Advisory at this time. Current have a Special Weather Statement out through 13z to cover what is currently out there. Fog should begin to burn off by 13z, which is what the hrrr has been indicating once mixing gets going.

Otherwise, pleasant autumn weather with a drier surface high pressure over the Mid-Atlantic will build into the region today, with PWATs dropping to around 0.50 inches. Persistent northeasterly low level flow into the mid- week should keep temperatures near to just below normal with dry weather expected. Weak surface ridging is expected to continue into the late week along with some building heights and temps returning to near-above average.

Attention turns to a more active weekend as moisture returns across the region with southerly to southeasterly flow aloft. Although guidance has struggled with the timing of 92L, currently in the Bay of Campeche and now at 80% probs of development in the next 7 days per the NHC, confidence is increasing in a tropical connection to this flow, with 18z run of the ECMWF joining the GFS in developing it into a TC and tracking north into the central Gulf Coast by this weekend or early next week. This will be the key component to whether we see appreciable rain with this setup. Without any tropical component, a broad surface ridging with a wedge setup will build and allow for widespread but weak overrunning with weak synoptic forcing (not dissimilar to last weekend...) and therefore a generally low QPF setup. With a tropical-synoptic shortwave to help drive both enhancement of PWATs and omega, a more notable rain event would be possible given the frontal boundary & overrunning favorability in place. Early deterministic and ensemble guidance runs have signaled that enhanced precip totals would be most favored along the GA/SC coast with interaction with a coastal front under this setup. Despite some increasing confidence this evening, solutions remain messy at this point and until a steady state surface low develops in the Gulf, uncertainty will remain high with this setup.

AVIATION /12Z TUESDAY THROUGH SATURDAY/

VFR conditions prevail through the TAF period.

With clearing cirrus moving out, there have been some areas of low stratus and fog formation early this morning. Greatest impacts will be seen in the central Midlands sites of CAE/CUB where ceilings below 400ft and visibilities below 2sm should be moving in at this time. Other sites are currently vfr, but even they could see brief restrictions through sunrise at any time. Once better mixing starts towards 13z, conditions are forecast to begin improving back towards vfr at all locations. Winds will pick up out of the east/northeast around 10 knots by 15z. A few gusts up to 15 knots can not be ruled out through the day before winds diminish prior to sunset once again.

EXTENDED AVIATION OUTLOOK...VFR conditions are expected into the mid to late week with drier air in place. Restrictions may become possible by the weekend.

CAE WATCHES/WARNINGS/ADVISORIES

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