textproduct: Charleston

WHAT HAS CHANGED

Key Message 1 has been updated to reflect fog chances tonight. Minor changes to Key Message 2 have been made to reflect the ongoing warm weather pattern into the middle of next week. The Aviation Section has been updated for the 18Z TAF issuance. The Marine Section has been updated for dense fog trends.

KEY MESSAGES

- 1) Areas to widespread fog anticipated across the majority of southeast South Carolina and southeast Georgia tonight into Saturday morning.

- 2) Unseasonably warm temperatures continue into the middle of next week, prior to a cold front arriving Thursday.

DISCUSSION

KEY MESSAGE 1: Areas to widespread fog anticipated across the majority of southeast South Carolina and southeast Georgia tonight into Saturday morning.

Observations across SE GA and the SC Lowcountry indicate the dewpoints ranged in the mid 60s to around 70 degrees. As temperatures warm in the low to mid 80s this afternoon, a sea breeze should develop late this afternoon. The sea breeze will advance inland this evening, maintaining dewpoints in the low to mid 60s. The surface ridge across the region will keep winds light or calm overnight. Forecast soundings from high resolution guidance indicates that the marine layer will extend up 1000 mb. Moisture below the inversion will likely form a layer of stratus, then build down to the sfc late tonight. Fog will be most likely around daybreak Saturday as temperatures cool in the low 60s. HREF indicates probabilities of less than a .5 mile range from 60% along the coast to 40% inland, especially across the SC Lowcountry. Dense Fog Advisory may be needed later for at least a portions of SE GA and SC Lowcountry, along with the adjacent Atlantic waters.

KEY MESSAGE 2: Unseasonably warm temperatures continue into the middle of next week, prior to a cold front arriving Thursday.

Deep-layered high pressure extending across the western Atlantic will prevail across the Southeast United States this weekend into the middle of next week, favoring a warm southerly flow under ample sunshine each day ahead of a stalling/dissipating front upstream Monday, then ahead of a more substantial cold front arriving to the local area during the second half of the week. The bulk of guidance continues to display 1000-850mb thicknesses supportive of afternoon high temps in the mid-upper 70s (coastal areas) to low-mid 80s (inland) this weekend and early next week, although scattered showers and/or an isolated thunderstorm could limit maximum heating. Greater warmth is possible heading into the middle of next week as mid-lvl ridging expands/strengthens across the Southeast United States in advance of a sfc cold front arriving Thursday. Latest guidance is suggestive of afternoon high temps in the mid-upper 80s (inland) Tuesday and Wednesday with mild overnight lows as well, generally in the lower 60s. These temperatures could come within a few degrees of records, particularly at Savannah, GA (KSAV). Chances of showers and thunderstorms increase with fropa on Thursday, limiting highs to the upper 70s/lower 80s, followed by noticeably cooler overnight lows in the upper 40s/lower 50s Thursday night.

AVIATION /18Z FRIDAY THROUGH WEDNESDAY/

Prior to the 18Z, visible satellite indicated sea fog along the coast, especially near the Savannah River. A sea breeze is expected to develop late this afternoon, bringing the marine layer across the terminals. IFR to LIFR ceilings should develop around 5Z, lowering through dawn. Dense fog is possible around dawn, highlighted with TEMPOs from 9-12Z. Fog and stratus will gradually improve during the daylight hours Saturday morning. Conditions should return to VFR by 16Z.

Extended Aviation Outlook: Flight restrictions are possible at CHS/JZI/SAV terminals due to fog and/or low stratus during late night/early morning hours during the weekend. Scattered showers and thunderstorms return Sunday and Monday, which could produce TEMPO flight restrictions at all terminals during afternoon/evening hours.

MARINE

This afternoon, visible satellite indicated sea fog along the coast, especially near the mouth of the Savannah River. Guidance indicates that sea fog will expand this evening, give sfc dewpoints in the 60s over waters in the 50s. The marine Dense Fog Advisory (DFA) for the nearshore waters south of the Edisto River has been extended until 10 AM Saturday. DFAs may be needed for additional marine zones later this evening or tonight. Otherwise, high pressure will provide the region with light winds and 3-4 ft seas.

Saturday through Tuesday: High pressure will remain the dominant weather feature across local waters this weekend, favoring a south/southeast wind in the 10-15 kt range and seas generally between 2-4 ft, well below Small Craft Advisory thresholds. Sfc winds could tip more south/southwest heading into early next week, but will continue to remain well below Small Craft Advisory levels between Atlantic high pressure and a stalling/dissipating front well inland.

CHS WATCHES/WARNINGS/ADVISORIES

GA...None. SC...None. MARINE...Dense Fog Advisory until 10 AM EST Saturday for AMZ352-354.