textproduct: Charleston

WHAT HAS CHANGED

Aviation section updated for the 12Z TAFs.

KEY MESSAGES

- 1) Patchy fog will be possible across the area early this morning.

- 2) Scattered to numerous showers with a few embedded thunderstorms should develop ahead of a cold front this afternoon.

- 3) Near-normal seasonal temperatures with dry conditions this weekend.

DISCUSSION

KEY MESSAGE 1: Patchy fog will be possible across the area early this morning.

Surface dewpoints across southeast GA and the SC Lowcountry will remain in the mid to upper 60s early this morning. IR satellite showed a large patch of high clouds and contrails across the region. Given thin cloud cover and light to calm surface winds, patchy fog or ground fog will remain possible through sunrise. Any fog that does develop should dissipate shortly after daybreak.

KEY MESSAGE 2: Scattered to numerous showers with a few embedded thunderstorms should develop ahead of a cold front this afternoon.

Temperatures this afternoon are forecast to peak in the low to mid 80s ahead of an approaching cold front. In addition, return flow show keep dewpoints in the low 70s along the coast to the mid to upper 60s inland.

A cold front is timed to sweep across southeast GA and the SC Lowcountry today, likely pushing over the adjacent Atlantic waters by 0Z. The timing of the front during the heat of the afternoon, should result in a field of SBCAPE between 1000 to 1500 J/kg with little to no CIN. The 0Z GFS indicates that an H5 trough will ripple across the southern Appalachians this afternoon. As the trough approaches the cold front, a frontal wave is expected to develop over the Midlands of SC, then tracking northeast along the cold front to the SC Grand Strand and eastern NC. Showers and thunderstorms coverage should concentrate within the frontal wave, tracking just inland and north of the forecast area. However, as the cold front slides over the forecast area, scattered to numerous showers with embedded thunderstorms should develop along and ahead of the cold front. Instability is expected to remain the greatest over the CHS Tri-county late this afternoon, likely supporting scattered thunderstorms. Rainfall amounts is forecast to range from 0.25-.5 inches near the northern Charleston and Berkeley County line, with 0.1-0.25 across the coastal counties, slightly less inland.

The front should push offshore in the evening hours. In the wake of the front, drier and cooler air will make a return with a rain-free forecast in place through early next week.

KEY MESSAGE 3: Near-normal seasonal temperatures with dry conditions this weekend.

Behind the cold front that pushed through, surface high pressure will be building into the southeast region on Saturday and into Sunday. Aloft, the trough axis will move through during the morning hours, with h500 heights starting to increase as a ridge of high pressure builds across the central US into Sunday. This will result in dry conditions throughout the weekend, with cooler near-normal temperatures expected across the region. With h850 temperatures ranging from 12 to 16 deg C, Saturday will see afternoon highs in the lower to mid 70s. Overnight, clear skies and light winds will result in cool temperatures as radiational cooling takes place. Lows away from the coast are expected to drop into the lower to mid 40s, with upper 40s to mid 50s for areas near to along the coast. While winds are expected to be light, any puff of wind may create wind chills down into the upper 30s to lower 40s.

The aforementioned surface high pressure expands into Sunday, with h850 temperatures topping out into the 10 to 12 deg C range. This will likely result in afternoon highs in the upper 60s to lower 70s, coolest across southeast South Carolina. Upper level ridging increases Monday into Tuesday, with afternoon highs back up into the mid 70s across the region.

AVIATION /12Z FRIDAY THROUGH TUESDAY/

Prior to the 12Z TAFs, patchy fog was observed across the region, with KJZI occasionally reporting dense fog. IR satellite showed a large patch LIFR SW of KSAV. Based on satellite trends, restrictive ceilings may reach KSAV between 12 to 15Z, highlighted with a TEMPO. Any fog that does develop should dissipate shortly after daybreak.

A cold front is timed to sweep across southeast GA and the SC Lowcountry today, likely pushing over the adjacent Atlantic waters by 0Z. The KCHS and KJZI TAFs will feature TEMPOs between 19-22Z for showers, with TSRA at KCHS. At KSAV, PROB30 at 19 to 21Z for showers. By 23Z, the cold front is expected to push east of the terminals, resulting in light winds veering from the NW.

Extended Aviation Outlook: Can't rule out an MVFR stratus deck developing behind the cold frontal passage overnight into Saturday morning. VFR conditions expected for the rest of the weekend into early next week.

MARINE

Ahead of a weak cold front, southerly winds will become southwesterly throughout the morning hours, with a few gusts possible into the upper teens. Can't rule out an isolated shower or two this morning, though the better chances for isolated to scattered showers and thunderstorms arrive later this afternoon into the evening hours. There is a chance we could see a thunderstorm or two that could produce gusty winds, so a special marine warning or two is possible later today.

The cold front pushes through this evening into the overnight period, bringing a switch to northeasterly winds overnight becoming northerly by Saturday morning. Wind gusts to near 20 knots are possible across the local waters, especially in the offshore (20- 60nm off the coast) zones, with waves building to 4 to 5 foot throughout the day. Unless things drastically change, not expecting a Small Craft Advisory at this time. Northeasterly winds continue into Sunday before decreasing into Monday, with no marine hazards expected.

CLIMATE

Record High Temperatures:

November 6: KCXM: 81/2003 KSAV: 86/2018

CHS WATCHES/WARNINGS/ADVISORIES

GA...None. SC...None. MARINE...None.