textproduct: Charleston

WHAT HAS CHANGED

New Aviation section. Removed key message #1.

KEY MESSAGES

- 1) Hazardous conditions are likely on Lake Moultrie late tonight into Saturday.

- 2) Dangerous fire weather conditions Saturday for much of Southeast South Carolina and Southeast Georgia with windy conditions at the coast. Red Flag Warnings are in effect with Wind Advisories along the coast.

- 3) Dry with above normal temperatures next week.

DISCUSSION

KEY MESSAGE 1: Hazardous conditions are likely on Lake Moultrie late tonight into Saturday.

Conditions will change quickly on Lake Moultrie tonight in the wake of a strong cold front. The front should reach the lake just after midnight with winds quickly increasing with its passage. North winds are expected to increase to 20-25 kt with gusts to 30 kt with waves building 2-3 ft. The highest winds and most significant wave action should occur over the central and southern portions of the lake. There may even be some minor lakeshore erosion and over splash along the lake's south side, including around Pinopolis, Lions Beach and Short Stay. Winds will begin to diminish by late morning then drop below Lake Wind Advisory thresholds (sustained 20 kt or frequent gusts to 25 kt) by early afternoon. A Lake Wind Advisory remains in effect for Lake Moultrie from midnight through 2 PM Saturday.

KEY MESSAGE 2: Dangerous fire weather conditions Saturday for much of Southeast South Carolina and Southeast Georgia with windy conditions at the coast. Red Flag Warnings are in effect with Wind Advisories along the coast.

Fire Weather: A dangerous and potentially high-impact fire weather event is becoming increasingly likely across the South Carolina Lowcountry and Southeast Georgia for Saturday. A strong cold front will push through the area late tonight and will be located over northern/central Florida by daybreak. Much drier/cooler air will advect in behind the front and dewpoints should mix out in the upper teens/lower 20s inland with mid- upper 30s along parts of the Georgia coast where a bit more of an onshore flow there due to the orientation of the coastline. As temperatures max out in the 60s (possibly around 70 in spots across Southeast Georgia), RH will reach critical thresholds by late morning and bottom out in the 15-25% range during the afternoon hours, a tad higher along the immediate Georgia coast. North winds 15-25 mph inland/20-30 mph coast with gusts 30-35 mph inland/30-40 mph coast will occur during the morning hours then diminish during the afternoon as cold air advection wanes and the pressure gradient begins to relax some. Although the highest winds and lowest RH will not be perfectly aligned there will be about a 4-6 hour period where the fire danger will be especially high for the region with conditions supportive for the rapid spread of wildfires.

State, federal and military land managers continue to report extremely dry fuels owing to severe to extreme drought conditions. Erratic and volatile fire behavior has been observed with controlled burns and wildfires over the past several days which will persist into Saturday. Given the expected RH, winds and the ongoing fuels/fire behavior situation, a Red Flag Warning has been issued for all but coastal portions of Liberty and McIntosh Counties, valid from 8 AM until 8 PM Saturday.

Coastal Winds: Coastal winds will be heavily influenced by the developing gales across the adjacent coastal waters induced by a tightening of the pressure gradient between high pressure wedging in from the north and the departing cold front. Winds of 20-30 mph with gusts 35-40 mph will be possible with some areas along the beaches possibly gusting 40-45 mph at times. A Wind Advisory has been posted for all coastal zones from 8 AM until 2 PM Saturday. Winds of this magnitude can down trees and large branches. Isolated power outages could occur.

KEY MESSAGE 3: Dry with above normal temperatures next week.

Mid-level ridging will prevail over the Southeast U.S. most of next week while surface High pressure is in the western Atlantic. This pattern will continue to bring dry conditions to our area. High temperatures will be slightly below normal on Sunday, then rise above normal on Monday. The warming trend continues Tuesday through Thursday.

AVIATION /00Z SATURDAY THROUGH WEDNESDAY/

A strong cold front will drop through the area late tonight. LAMP MOS indicates low chance for brief MVFR ceilings at KCHS and KZJI for 1-2 hrs around daybreak Saturday, but we did not include any flight restrictions at this time.

The main story continues to be the strong winds developing late tonight behind the front. Sustained winds close to 20 kt expected at all three terminals for much of the day Saturday, with gusts approaching 30 kt at times. Wind speeds should start to slowly decrease by late Saturday afternoon.

Extended Aviation Outlook: VFR.

MARINE

The main concern through Wednesday continues to center on the potential for gales over the all waters late tonight into Saturday. Models are similar in showing a strong cold front working south across the coastal waters overnight, likely pushing into northern/central Florida by daybreak Saturday. Behind the front, winds will quickly increase owing to a tightening of the pressure gradient between the front and high pressure wedging in from the north and some post frontal cold air advection. Frequent gusts to gale force should develop over the waters a few hours prior to daybreak with sustained gales possible over the Georgia offshore waters. The forecast will show 25-30 kt with gusts to 35-40 kt nearshore waters with 30-35 kt with gusts to 40-45 kt over the Georgia offshore waters. Even in the Charleston Harbor, gusts to 35 kt gales look likely, especially near the Harbor Entrance. The Gale Watch has been upgraded to a Gale Warning to reflect these conditions. The risk for gales should end across the Harbor and nearshore waters by early Saturday afternoon and the Georgia offshore waters by late Saturday evening. Seas will peak 6-9 ft nearshore waters and 9-12 ft over the Georgia offshore waters late Saturday night into Sunday. Small Craft Advisories will replace the Gale Warnings once they expire.

High Surf: Breaking wave heights could reach 5-6 ft along parts of the Georgia coast Sunday. A High Surf Advisory may be needed.

CLIMATE

Record High Temperatures:

March 27: KCHS: 87/2021 -- Reached 89 today KCXM: 81/2021 -- Reached 82 today KSAV: 89/2021 -- Reached 89 today

CHS WATCHES/WARNINGS/ADVISORIES

GA...Red Flag Warning from 8 AM to 8 PM EDT Saturday for GAZ087-088- 099>101-114>119-137-138-140. Wind Advisory from 8 AM to 2 PM EDT Saturday for GAZ117-119- 139-141. SC...Red Flag Warning from 8 AM to 8 PM EDT Saturday for SCZ040- 042>045-047>052. Wind Advisory from 8 AM to 2 PM EDT Saturday for SCZ048>051. Lake Wind Advisory from midnight tonight to 2 PM EDT Saturday for SCZ045. MARINE...Gale Warning from 3 AM to 2 PM EDT Saturday for AMZ330. Gale Warning from 3 AM to 6 PM EDT Saturday for AMZ350. Gale Warning from 5 AM to 6 PM EDT Saturday for AMZ352-354. Gale Warning from 5 AM Saturday to 2 AM EDT Sunday for AMZ374.