textproduct: Charleston

WHAT HAS CHANGED

All sections updated. The Aviation section has been updated for the 12Z TAFs.

KEY MESSAGES

- 1) Areas across the South Carolina Lowcountry and southeast Georgia will see gusty northeast winds with relative humidity values around 30 percent today.

- 2) Near-record warmth Friday before a dry cold front brings cooler temperatures this weekend.

DISCUSSION

KEY MESSAGE 1: Areas across the South Carolina Lowcountry and southeast Georgia will see gusty northeast winds with relative humidity values around 30 percent today.

The backdoor cold front is expected to push south of the forecast by daybreak this morning. Isolated showers last evening produced some swaths of rainfall across portions of Berkeley, Charleston, and Colleton Counties up to a tenth of an inch. The pressure gradient across the forecast area will range between 3-4 mbs this morning, then gradually decreasing this afternoon. This pattern should support gust of 20 to 25 mph through mid-day, with occasional gusts to 20 mph this afternoon. The northeast winds and mixing in excess of 3 kft should allow dewpoints to remain around 30 degrees through early this afternoon, with some recovery late this afternoon. As temperatures warm into the low 60s this afternoon, some inland locations may see relative humidity values fall to around 30 percent. Weather conditions are marginal for a Fire Danger Statement across our inland counties this afternoon. However, we will headline the low relative humidity and gusty winds in the FWF.

KEY MESSAGE 2: Near-record warmth Friday before a dry cold front brings cooler temperatures this weekend.

The 500 mb level will consist of a broad 588 dam High over TX Friday, with it's eastern periphery stretching into the Southeast U.S. This will cause a brief rise in heights over our area. At the surface, High pressure will be in the western Atlantic. This pattern will yield near-record high temperatures on Friday. Highs will range from the upper 80s to lower 90s, except cooler at the beaches due to the sea breeze.

A dry cold front is expected to move through Friday night into Saturday, ushering in significantly cooler temperatures. Lows could even drop into the upper 30s across northern interior counties, including Berkeley, Dorchester, and Colleton. High temperatures should be a few degrees below normal for the weekend, ranging from the mid to upper 60s across our SC counties to the lower 70s across our GA counties.

AVIATION /12Z TUESDAY THROUGH SATURDAY/

VFR conditions are expected at CHS/JZI/SAV terminals through 12Z Wednesday. MOS and forecast soundings indicate that northeast winds will favor values of 10-15 kts with gusts around 20 kts through the daylight hours. Gusts are forecast to end around 0Z with northeast winds remaining between 5 to 10 kts through the rest of the TAF period.

Extended Aviation Outlook: VFR. Expect gusty winds behind a dry cold front on Saturday.

MARINE

Today: The pressure gradient is forecast to remain between 4-5 mbs into midday. Winds across the Atlantic waters, outside the Charleston Harbor, are forecast to yield gale gusts through the daylight hours. The Gale Warning will remain in effect for the nearshore waters until 11 PM this evening and until 2 AM for the outer GA waters. In addition, wave heights are forecast to peak this evening , ranging from 6-9 ft within 20 NM and 9-11 ft between 20-60 NM. Small Craft Advisory has been issued for the Charleston Harbor, with NE gusts around 30 knots until 11 PM.

Small Craft Advisories (SCAs) will likely replace the Gale Warnings tonight. Gusts may range near 25 kts through late tonight, SCAs would primarily highlight seas of 6 ft or more tonight.

Extended Marine: High pressure building into the region will cause winds and waves to trend lower Wednesday. Though, elevated waves will persist over the GA waters beyond 20 nm into Wednesday night. A dry cold front is expected to move through Friday night into Saturday, bringing near gale to possibly gale conditions to all of our coastal waters.

CLIMATE

Record High Temperatures:

March 27: KCHS: 87/2021 KCXM: 81/2021 KSAV: 89/2021

CHS WATCHES/WARNINGS/ADVISORIES

GA...None. SC...None. MARINE...Small Craft Advisory until 11 PM EDT this evening for AMZ330. Gale Warning until 11 PM EDT this evening for AMZ350-352-354. Gale Warning until 2 AM EDT Wednesday for AMZ374.