textproduct: Charleston

SYNOPSIS

High pressure will persist today, then a cold front will move through on Sunday. High pressure will rebuild through the middle of the week, then another cold front will move through Thursday.

NEAR TERM /THROUGH TONIGHT/

Early this morning, GOES Nighttime microphysics and sfc-based observations indicated patchy to widespread fog and low clouds generally east of I-95. The fog and low clouds should persist across the coastal counties of the SC Lowcountry through daybreak this morning. It is possible that patchy dense fog may develop along the coast, possibly highlighted with a Special Weather Statement. The fog should rapidly dissipate during the early daylight hours as southwest winds strengthen.

Today, the forecast area will remain between a cold front approaching from the west as high pressure remains centered over the western Atlantic. As the front approaches, the pressure gradient across the region will gradually steepen. Gusty southwest winds should develop by mid-morning, peaking during the early afternoon hours. Thicknesses between 1000-850 mb is expected to gradually increase. The mild thicknesses combined with some breaks in the cloud cover should yield another very warm and dry afternoon across the region today. In fact, the high temperature at KSAV may peak within a degree or two of the record, 81 set in 1972.

Tonight, the cold front is timed to reach the inland counties of the forecast area after midnight, pushing offshore before daybreak on Sunday. Guidance has trended drier with the passage of the front, with isolated to scattered showers possible inland and isolated east of I-95. Little to no measurable rainfall is forecast east of I-95. The passage of the front will yield gusty northwest winds across the region by late tonight. A Lake Wind Advisory has been posted to highlight gusts of 25 kts or more across Lake Moultrie late tonight.

SHORT TERM /SUNDAY THROUGH TUESDAY/

The cold front is expected to be offshore by noon Sunday, with only isolated rain showers accompanying it. High temperatures will likely occur by 11am, followed by a steady drop through the afternoon. Gusty winds expected from late morning through mid to late afternoon as low- level winds increase and good mixing occurs in the cold advection. A Lake Wind Advisory is in effect until 7pm Sunday for Lake Moultrie for frequent 25 kt gusts.

Dry, cool weather expected Sunday night through Tuesday.

LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/

A deep upper trough will approach mid-week with surface low pressure developing over the Mid-Atlantic. A cold front will move through Wednesday night or Thursday, potentially bringing a few showers to the area.

AVIATION /06Z SATURDAY THROUGH WEDNESDAY/

Prior to the 6Z TAFs, observations and satellite have indicated some degree of fog and stratus at the terminals, especially KCHS and KJZI. Based on HRRR sfc condensation pressure deficits and MOS, IFR and LIFR ceilings may develop early this morning, occurring with rounds of IFR fog. Ceilings should reach the lowest levels around dawn. As a cold front approaches from the west today, southwest winds should begin to strengthen during the early daylight hours, peaking early this afternoon. Momentum transfer should yield gusts into the teens to low 20s through this afternoon. The strengthen winds should mix out low ceilings this morning, with VFR by 14Z. Southwest winds should continue through this evening, with gusts decreasing into the teens by late this afternoon.

Extended Aviation Outlook: A band of showers with a cold front may bring reduced vsbys Saturday night into early Sunday morning. Gusty northwest winds are expected during the day Sunday.

MARINE

Today, the marine zones will remain between a cold front approaching from the west as high pressure remains centered over the western Atlantic. As the front approaches, the pressure gradient across the region will gradually steepen. Gusty southwest winds should become common during the daylight hours, but remaining less than 25 kts. As a result, wave heights are forecast to gradually build, reaching 2-3 ft this afternoon.

Tonight, the cold front is timed to push offshore before daybreak on Sunday. Gusty southwest winds will remain ahead of the front, then veering with FROPA from the northwest. Gusts are forecast to increase into the 20s, with 25 kts across the nearshore waters of Charleston County after midnight, highlighted with a Small Craft Advisory. Winds and seas will increase across the coastal waters through daybreak on Sunday.

Winds turn W behind the cold front Sunday morning, then NW by afternoon. Deep mixing and strong low-level wind fields will likely produce 25 kt gusts across all waters for much of the day Sunday into Sunday night, necessitating Small Craft Advisories. Improving conditions early next week as high pressure builds over the area.

CLIMATE

January 10: KCHS: 79/2008 KSAV: 81/1972

Record High Minimum Temperatures: January 10: KCHS: 60/1974 KCXM: 62/1974 KSAV: 63/1937

CHS WATCHES/WARNINGS/ADVISORIES

GA...None. SC...Lake Wind Advisory from 11 PM this evening to 7 PM EST Sunday for SCZ045. MARINE...Small Craft Advisory from 9 AM to 8 PM EST Sunday for AMZ330. Small Craft Advisory from 2 AM Sunday to 6 AM EST Monday for AMZ350. Small Craft Advisory from 9 AM Sunday to 6 AM EST Monday for AMZ352-354-374.