textproduct: Charleston

WHAT HAS CHANGED

The Aviation Section was updated for the 06z TAFs. A Small Craft Advisory has been issued for all marine waters outside of the Charleston Harbor from Monday morning through Tuesday night.

KEY MESSAGES

- 1) A cold front will advance through the region this afternoon bringing numerous showers and thunderstorms.

- 2) Cooler temperatures expected for the work week.

DISCUSSION

KEY MESSAGE 1: A cold front will advance through the region this afternoon bringing numerous showers and thunderstorms.

A mid-level trough extended southward from the Great Lakes into the Ohio Valley region will swing eastward today, while at the surface a cold front pushes through the southeastern states. Ahead of the approaching cold front moisture is expected to build into the region, with PWATs increasing to 1.5 to 1.6" by the afternoon. Additionally, dew points are forecast to surge into the mid to upper 60s, which combined with daytime highs in the low to mid 80s, will yield a rather muggy feeling day. A band of showers and thunderstorms is expected to arrive with the front this afternoon. Given the pre-frontal environment, with ML CAPE values around 400-700 J/kg and shear around 2-30 knots, a strong to severe thunderstorm is possible, especially across the Charleston Tri-County where instability is forecast to be the strongest. Damaging wind gusts are the main threat. Significant rainfall is not anticipated, with amounts generally topping out around 0.5". After the front pushes through in the evening hours some lingering weak showers are possible along the coastal counties into the overnight.

KEY MESSAGE 2: Cooler temperatures expected for the work week.

Notably cooler temperatures are expected behind the cold front, as a wedge of high pressure sets up off the northeast coast into Wednesday. Afternoon highs in the upper 60s to 70s are expected for Monday, rising slightly into the lower to mid 70s on Tuesday before the high pressure wedge sets in. Wednesday will see temperatures back down into the upper 60s to lower 70s, slowly rising into the 80s by Saturday as the wedge erodes.

Mostly dry conditions are expected Monday through Wednesday, though can't rule out some weak/light showers for areas in/near McIntosh county in southeast Georgia. Areas well west of the I-95 corridor may see an elevated fire danger risk as dry relative humidities near 30% and breezy winds develop during the afternoon hours Monday through Wednesday, further aided by the ongoing drought conditions.

AVIATION /06Z SUNDAY THROUGH THURSDAY/

VFR will initialize at KCHS/KJZI/KSAV and prevail into the afternoon. A cold front is progged to push through the region later this afternoon, with a line of showers and thunderstorms accompanying it. Gusty SW winds will develop this morning at all terminals, gusting to around 20 knots with gusts to 25 knots possible at KCHS/KJZI. Best chances for a shower/tstorm are at KCHS/KJZI where a TEMPO group has been introduced from 21-24Z today for TSRA. Have only included mention of VCSH at KSAV as the line of showers will weaken further southward. Showers could linger across the coastal counties of SC into tonight so VCSH is in place at KCHS/KJZI beginning at 00Z and prevailing through the remainder of the 06Z TAF period.

Extended Aviation Outlook: Improving conditions behind the cold front by Monday morning. VFR expected into the extended.

MARINE

Today and Tonight: A cold front will approach from the west this afternoon, with an associated line of showers and thunderstorms late this afternoon and this evening. Some of these thunderstorms could produce gusts >34 knots and Special Marine Warnings may be required. In the wake of the cold front a surge in wind gusts and building seas are forecast, with Small Craft Advisories in effect by daybreak Monday.

Monday through Thursday: Winds are expected to remain breezy as surface high pressure moves in behind the cold front bringing gusts up to 30 knots, continuing the Small Craft Advisories into at least Wednesday morning. Will likely see wind gusts subside below the 25 knot threshold late Monday afternoon into early Tuesday, though wave heights above 6 feet will continue. Expect winds to increase again on Tuesday as a strong surface high pressure wedge sets up along the northeast coast into Wednesday, which will likely require an upgrade to Gales for all zones with the Charleston Harbor likely needing at least a Small Craft Advisory by Wednesday morning.

Rip Currents: Today: The combination of gusty S to SW winds and a 3 ft SE swell near 8 seconds will result in a Moderate Risk of rip currents at all beaches.

Monday: The combination of gusty NE winds and 3 to 4 ft SE swell near 9 seconds will result in a Moderate Risk of rip currents at the Georgia beaches.

CHS WATCHES/WARNINGS/ADVISORIES

GA...None. SC...None. MARINE...Small Craft Advisory from 5 AM Monday to 2 AM EDT Wednesday for AMZ350-352. Small Craft Advisory from 8 AM Monday to 2 AM EDT Wednesday for AMZ354-374.