Allendale, SC Weather

What Has Changed

Key Message 2 was updated to cancel the Coastal Flood Advisory this morning as tide levels in the Charleston Harbor have dropped below minor flood stage. The Aviation section was updated for the 23/12z TAFs.

Key Messages

- 1) Dry conditions and below normal temperatures will continue into early next week.

- 2) Multi-day coastal flooding event expected this weekend into next week.

- 3) Strong northeast flow this weekend and into early next week will result in several coastal hazards including rip currents, high surf, and beach erosion.

Discussion

KEY MESSAGE 1: Dry conditions and below normal temperatures will continue into early next week.

Through Daybreak: Conditions early this morning are the same as the past several. Clear skies, calm winds within a decoupled boundary layer and a resident dry airmass are promoting strong radiational cooling. Hourly temperatures are running a few degrees colder than the 23/01z NBM, which is not surprising given its classic warm bias in strong radiational regimes. Lows were adjusted down from the NBM given current trends and are on track to bottom out in the lower-mid 40s inland to the upper 50s at the beaches. The pressure gradient is forecast to slightly tighten as daybreak approaches which should curtail the radiative processes in some areas, especially east of I-95.

Today and Tonight: There is no change in the surface pattern with strong high pressure prevailing. High temperatures today will run just a bit cooler than Thursday with temperatures aloft forecast to cool slightly as a strong shortwave drops south along the Southeast U.S. coast. Even with the cooler temperatures aloft, full insolation is expected with highs poised to warm into the lower-mid 70s away from the beaches. The pressure gradient will begin to quickly tighten tonight as low pressure begins to organize east of the Southern Bahamas and strong high pressure centered over New England steadily wedges south across the Carolinas and Georgia. This will result in a uptick in winds through the night with breezy conditions developing at the beaches and around the Santee-Cooper lakes. Despite clear skies, it will be an overall warmer night with lows ranging from the upper 40/lower 50s inland to around 60 at the beaches. Some mid 40s could occur, mainly in the Jenkins- Allendale corridor where winds will be the lightest.

Saturday through Thursday: Surface high pressure will extend across the region through late week. Over the weekend, the high will strengthen inland while a coastal trough develops offshore. The air mass will remain quite dry. The pattern will support a rain-free forecast through at least early next week. Despite plenty of sunshine, temperatures will lean on the cooler side of normal. Highs will top out in the lower to mid 70s for the weekend and early next week. Low temperatures will fall into the 40s across many interior locations.

KEY MESSAGE 2: Multi-day coastal flooding event expected this weekend into next week.

Astronomical tides will continue to rise through the weekend and into next week with the upcoming lunar perigee (10/28) and full moon (10/26). With another period of strong northeast flow on the way this weekend into next week, large tidal departures will start to overlap with increasing astronomical tides, providing increased probabilities of seeing a multi-day coastal flooding event for the entire coast.

Aviation

23/12z TAFs: KCHS/KJZI/KSAV: VFR through 24/12z.

Extended Aviation Outlook: Breezy northerly winds anticipated through Monday morning. Gusts could reach 25-30 kt, especially during the afternoon hours Saturday and Sunday.