textproduct: Charleston

WHAT HAS CHANGED

The aviation section has been updated for the 18Z TAF issuance.

KEY MESSAGES

- 1) A period of unsettled and warm conditions for the end of the week into the weekend.

DISCUSSION

KEY MESSAGE 1: A period of unsettled and warm conditions expected for the end of the week and into the weekend.

A ridge of high pressure centered over the Gulf of America builds overnight into Thursday, with warm and moist southwesterly surface flow setting up over the region into the weekend. Temperatures throughout the atmospheric column consistently reach and/or exceed the 90th percentile wrt climatology, as the latest ensemble situational awareness tables continue to show, which will result in daily maximum surface temperatures in the mid 70s to lower 80s Thursday through Saturday, peaking on Friday. Overnight low temperatures will be similarly warm in the upper 50s to lower 60s, which will be closer to our normal daily highs for this time of year. The forecast does not currently contain any new records, though we'll get closest to the record temperatures set for February 20 as we'll be warmest that day with inland areas in the lower to mid 80s.

While isolated showers will be possible Thursday (10-20%), rain chances ramp up Friday into Saturday with scattered to numerous diurnally driven showers forecast. Isentropic lift from positive theta-e advection will add to the unsettled conditions. Instability will rise ahead of an incoming cold front from the northwest, which looks to push across the area Saturday night. Saturday's peak SBCAPE values in excess of 500 J/kg and bulk shear around 20 kt are worth watching for this time of year. While details are unclear, some of the various AI/ML output would suggest monitoring for strong to severe thunderstorms Saturday.

AVIATION /18Z WEDNESDAY THROUGH MONDAY/

VFR conditions are expected at CHS/JZI/SAV terminals through 18Z Thursday. Prevailing southwest winds with gusts around 20 kt will continue until sunset before quickly subsiding. Southwest winds will once again become gusty Thursday afternoon. Patchy ground fog should be limited overnight to areas far inland, well away from the terminals, as mid and high clouds pass over; thus no mention in the TAF.

Extended Aviation Outlook: The potential for flight restrictions will increase late week into the weekend with possible fog development during the pre-dawn hours, as well as increasing rain chances especially Friday and Saturday.

MARINE

High pressure will prevail over the western Atlantic through the end of the week, bringing southwest winds. There could be a bit of a wind surge on Friday, which may bring Small Craft Advisories for portions of our waters during that time period, especially the Charleston waters. A cold front is expected to move through the waters late Saturday into early Sunday. Expect winds to clock around to the northwest on Sunday and increase, bringing near gale to gale conditions to all of our ocean zones.

Sea Fog: South to southwest winds will usher higher dew points over the cooler shelf waters into this weekend. This pattern generally makes it easier for sea fog to form. However, there will be periods of stronger winds closer to the coast and this tends to make it more difficult for sea fog to form and/or maintain itself. Additionally, periods of showers Friday and Saturday could have similar impacts. Therefore, we have patchy fog in the forecast at times. However, this portion of the forecast will need to be adjusted, especially based on near term observational trends.

CLIMATE

Record High Temperatures:

February 20: KCHS: 82/2018 KCXM: 78/1918 KSAV: 84/1991

CHS WATCHES/WARNINGS/ADVISORIES

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