textproduct: Charleston

SYNOPSIS

High pressure builds across the area through Tuesday, followed by a cold front Wednesday night. High pressure then returns heading into the weekend.

NEAR TERM /THROUGH TONIGHT/

A positively tilted upper level trough will progress this afternoon across the eastern CONUS. At the surface a cold front has pushed through the region, now positioned off the southeastern coast. Cold air advection will dominate the rest of the afternoon as 850 hPa temperatures drop roughly 10 degrees from sunrise this morning to sunset this evening. Additionally the pressure gradient in the low levels will be pinched as high pressure builds in behind the departing cold front. Between the tight pressure gradient and the CAA regime, gusty winds are expected across the region, generally around 25 mph, with some gusts to 30 mph possible across the Charleston Tri- County. A Lake Wind Advisory remains in effect for Lake Moultrie through this afternoon. In addition to the gusty winds, drier air will infiltrate the region, with RH values dropping to between 25 and 30%. A Fire Danger Statement has been issued for southeast SC and southeast GA. See the Fire Weather section for more details. Temperatures this afternoon have likely reached their maximum as of the early afternoon, with CAA ushering in a cooler airmass.

High pressure will continue to build into the region tonight. Gusts should wane with nightfall, however given strong CAA through the overnight period winds should remain around 10 mph through the night. Low temperatures are expected to be in the upper 20s far inland, with low to mid 30s along the coastline. These temperatures combined with a little bit of wind will likely yield wind chill values in the mid to upper 20s. While not cold enough for a Cold Weather Advisory, these temperatures are significantly colder than anything observed the last several days.

SHORT TERM /MONDAY THROUGH WEDNESDAY/

Dry and seasonally cool temperatures prevail heading into the new week as sfc high pressure builds overhead. With the aid of northerly winds and CAA, only have highs rising into the lower 50s across the area. Overnight lows will also feel quite chilly, as temperatures range from the upper 20s inland to mid 30s along the coast. Winds shift to the southwest by Wednesday, allowing temperatures to moderate back into the upper 50s to lower 60s.

Upper level ridging digs across the Ohio River Valley Wednesday, with an attendant sfc cold front also pushing eastward during this time. As noted in the previous discussion, this boundary is progged to impact the area Wednesday. While rain chances could begin as early as Wednesday morning, expect the better probabilities (20-30%) to occur during the afternoon/evening. Nonetheless, given the lack of upper level moisture, not expecting to see much in the way of meaningful rainfall. Rather, the more notable impacts look to occur Thursday - more on this in the section below.

LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/

Will see a resurgence of CAA Thursday in the wake of FROPA, limiting highs into the upper 40s to lower 50s, which is certainly well below seasonal norms. In addition to this, expect west-northwesterly winds to become fairly breezy. Currently have gusts between 25 to 30 MPH possible for much of the area Thursday afternoon.

Breezy conditions then subside by Friday as sfc high pressure builds across the southeast. Otherwise, look for dry conditions to prevail into Saturday, with temperatures slowly moderating back into the 50s.

AVIATION /18Z SUNDAY THROUGH FRIDAY/

VFR conditions will prevail through the 18Z TAF period at KCHS/KJZI/KSAV. Gusty NW winds will dominate this afternoon, gusting around 30 knots at all terminals. Gustiness will wane with nightfall, however winds will remain slightly elevated overnight, generally 5 to 10 knots. Winds will shift from the NW to the NE around daybreak Monday.

Extended Aviation Outlook: VFR.

MARINE

Rest of Today and Tonight: High pressure will build into the region at the surface in the wake of a cold front. As the pressure gradient tightens between the two features, NW winds will gust 25 to 30 knots across all marine zones. Small Craft Advisories remain in effect through this afternoon. While the SCA for the Charleston Harbor expires this evening, the SC/GA Atlantic waters should see SCA conditions last into early Monday morning. In addition, seas will build through this evening, ranging between 3-6 ft.

Monday Onward: Winds continue to weaken Monday as sfc high pressure builds overhead, allowing tranquil marine conditions to prevail through mid-week. The next chance for Small Craft Advisories will be Thursday and Thursday night as winds increase behind another cold front.

FIRE WEATHER

In the wake of a cold frontal passage this morning drier air and gusty winds have been ushered into the region. As of the early afternoon RH values have dropped to around 30% across a large portion of southeastern SC and southeastern GA accompanied by NW wind gusts 20 to 25 mph. After coordination with local partners a Fire Danger Statement has been issued for the entire forecast area, valid through 7 PM this evening.

CHS WATCHES/WARNINGS/ADVISORIES

GA...None. SC...Lake Wind Advisory until 7 PM EST this evening for SCZ045. MARINE...Small Craft Advisory until 8 PM EST this evening for AMZ330. Small Craft Advisory until 7 AM EST Monday for AMZ350-352-354- 374.