textproduct: Charleston

WHAT HAS CHANGED

Key Message 1 was updated for overnight shower trends. The Aviation Section has been updated for the 00Z TAF issuance. The Marine Section has been updated for trends in the Charleston Harbor.

KEY MESSAGES

- 1) Mild temperatures expected through midweek, then a cold front should bring at least scattered showers on Thursday.

DISCUSSION

KEY MESSAGE 1: Mild temperatures expected through midweek, then a cold front should bring at least scattered showers on Thursday.

Tonight: Water vapor imagery indicates substantial dry air residing across the local area, and likely responsible for rain-free conditions across Southeast South Carolina and any precip activity remaining rather sparse across Southeast Georgia post sunset this evening. However, a weak coastal continues to spawn shower activity across the nearby Atlantic which could make a run toward the coast during overnight hours at times within a northeast flow occurring along the eastern periphery of high pressure over land and north. Given the amount of dry air aloft, precip should struggle to make significant inland progress. Low temperatures are forecast to range from 55 to 60 inland to the low 60s along the coast.

High pressure will be centered over the north Atlantic on Tuesday which will allow for the northeast gradient along the coast to gradually break down into Wednesday as a front begins to approach from the west. The front should arrive into the area Friday morning and then move offshore Friday night. For Tuesday and Wednesday, shower activity should continue offshore over the coastal waters but could try to push onshore at times. But overall, mostly dry. As the front gets closer Thursday and into Friday, the potential is higher for increased shower coverage though model guidance continues to be rather underwhelming regarding the rainfall potential. The forecast continues to feature 20-30 percent chances Thursday and Friday. Temperatures will remain mild, with highs in the low 80s through the week followed by mid to upper 70s over the weekend.

AVIATION /00Z TUESDAY THROUGH SATURDAY/

VFR conditions should prevail through 00Z Wednesday at CHS/JZI/SAV terminals. However, latest radar/satellite trends suggest TEMPO MVFR cigs and light rain could impact the SAV terminal into late evening hours. Otherwise, east-northeast winds should become gusty at all terminals by around 15Z Tuesday (15-20 kt), before trending weaker by 22-23Z.

Extended Aviation Outlook: Northeast winds could produce wind gusts up to around 20 knots Tuesday afternoon and evening. Increased shower coverage is expected with a front Thursday and Friday.

MARINE

Tonight: The surface pattern should generally support NE winds between 15 to 20 kts and gusts around 25 kts through the near term. As a result, wave heights should remain between 5 to 7 ft. Small Craft Advisories will remain in effect for all nearshore waters out 20 nm and the 20 to 60 nm offshore GA waters. However, winds continue a weaker trend across the Charleston Harbor post sunset, and therefore support ending a Small Craft Advisory across the harbor for the night.

Tuesday through Saturday: High pressure situated to the north will drift further over the north Atlantic on Tuesday. This will keep the tight pressure gradient and enhanced northeast flow across the local waters going with speeds mostly in the 15-20 knot range. By Wednesday, the gradient will relax and winds will turn more easterly with speeds no more than 10-15 knots. Then for Thursday, a front will approach from the west and winds will turn more southerly and light (5-10 knots). The front is expected to pass through Friday and Friday night with no significant surge behind it. Ongoing Small Craft Advisories will come to an end across the nearshore waters on Tuesday with decreasing winds and seas. The advisory for the outer GA waters will extend into Wednesday to account for lingering 6 ft seas.

CHS WATCHES/WARNINGS/ADVISORIES

GA...None. SC...None. MARINE...Small Craft Advisory until 7 PM EST Tuesday for AMZ360-362-364. Small Craft Advisory until 1 PM EST Wednesday for AMZ384.