textproduct: Charleston

WHAT HAS CHANGED

The Aviation Discussion was updated for the 18z TAFs.

KEY MESSAGES

- 1) Expect cold temperatures tonight into Tuesday morning as wind chills drop into the low to mid 20s.

- 2) A cold front will bring rain showers to the South Carolina Lowcountry and Southeast Georgia late Tuesday night into Wednesday night.

DISCUSSION

KEY MESSAGE 1: Expect cold temperatures tonight into Tuesday morning as wind chills drop into the low to mid 20s.

Surface high pressure will settle along the Eastern Seaboard tonight yielding calm winds and clear skies across the region through Tuesday morning. This combined with a dry low-lvl airmass in-place will support strong radiational cooling overnight. Temperatures are forecast to be well below normal and the ESAT NAEFS highlights this well with a standard deviation of -3.5 for minimum temperatures on Tuesday morning. It's also fairly high model confidence as IQR shows a 1 to 2 degree spread for minimum temperature values. Expect low temperatures to range into the low to mid 20s inland and mid to upper 30s at the beaches overnight. Mixed the NBM/NBM25 into the overnight temperatures as the 02/13Z NBM appeared to be struggling to realize the strength of the radiational cooling regime. 02.12Z HREF probabilities indicate less than 5% chance of temperatures dropping below 20 degrees and therefore a Cold Weather Advisory is not warranted at this time.

KEY MESSAGE 2: A cold front will bring rain showers to the South Carolina Lowcountry and Southeast Georgia late Tuesday night into Wednesday night.

A positive tilt upper trough will dive into the central United States on Wednesday, moving off the Southeast coast on Thursday. An associated cold front will sweep through the local area Wednesday and Wednesday night. A fairly substantial increase in atmospheric moisture ahead of the front (PWs ~1.1" Wed PM) should support numerous to widespread rain showers ahead of the front. Showers could be moving into interior SC/GA late Tuesday night, with the greatest coverage during the day Wednesday. Precipitation should be mostly off the coast by daybreak Thursday. Much colder air will move in late Wednesday night, though the precipitation is expected to outrun the sub-freezing low-level air by about 6 hrs, so we do not anticipate any precipitation-type concerns. Total precipitation with the cold front should range from 0.2"-0.5".

AVIATION /18Z MONDAY THROUGH SATURDAY/

02/18z TAF Discussion: KCHS/KJZI/KSAV: VFR through 03/18z.

Extended Aviation Outlook: A cold front will bring flight restrictions Wednesday through Wednesday evening, mainly due to rain showers. VFR returns on Thursday.

MARINE

Through tonight: Relatively quiet conditions through the evening across the local waters with west-northwesterly winds at 5 to 10 kt persist. Elevated seas above 6 ft will linger through sunset for the Georgia offshore waters where a Small Craft Advisory is in effect until 7PM.

Tuesday and Wednesday: Quiet marine conditions persist into Tuesday as high pressure holds control of the local waters. Southwesterly winds will average less than 15 kt. As a cold front approaches the region on Tuesday night, southwesterly winds will increase to 15 to 20 kt with gusts up to 22-23. Thereafter, expect winds to dial down on Wednesday afternoon. Seas will range 2 to 3 ft the nearshore waters and 4 to 5ft in the outer Georgia waters.

Thursday through Friday: We'll see an increase in W winds on Friday behind the cold front. We may eventually need a Small Craft Advisory for the offshore GA waters Friday and Friday night due to 25 kt winds and 6-7 ft seas.

CLIMATE

February 3: KCHS: 21/1940

EQUIPMENT

The KCLX radar is operational, but could go down at any time. Additional repairs are needed.

CHS WATCHES/WARNINGS/ADVISORIES

GA...None. SC...None. MARINE...Small Craft Advisory until 7 PM EST this evening for AMZ374.