textproduct: Charleston

WHAT HAS CHANGED

All Key Messages and sections were updated.

KEY MESSAGES

- 1) Record-setting heat possible today and Saturday as dry weather continues.

- 2) Minor coastal flooding possible along the South Carolina coast with the evening high tides this weekend.

- 3) A cold front will bring low end rain chances Sunday, followed by a brief cooldown early next week.

DISCUSSION

KEY MESSAGE 1: Record-setting heat possible today and Saturday as dry weather continues.

Mid-level ridging continues to prevail across the Tennessee River Valley as sfc high pressure sits tight overhead. As noted in days past, this pattern will continue to favor dry conditions and above normal temperatures, at least through Saturday. Currently have afternoon highs in the low to mid 90s for a vast majority of our area, which may put a few daily records in jeopardy (see climate section below).

Additionally, the latest Drought Monitor indicates D4/Exceptional Drought over a small portion of interior southeast GA, with a recent expansion of the D3/Extreme Drought to encompass much of the remaining area. These persistent, very dry conditions combined with RH values dipping into the mid-20s ahead of the sea breeze this afternoon and Saturday afternoon could result in elevated fire weather concerns, though winds should remain light enough to keep the threat for rapid wildfire spread limited. Nonetheless, we encourage folks to exercise caution with any activity that may cause a spark.

KEY MESSAGE 2: Minor coastal flooding possible along the South Carolina coast with the evening high tides this weekend.

The combination of the new moon (today) and perigee (Sunday) will bring elevated astronomical tidal ranges this weekend into early next week. Minor coastal flooding is possible with the Saturday evening high tide along the South Carolina coast. Tide levels will be elevated again with the Sunday evening high tide, but the coastal flooding threat is uncertain and dependent on the timing of the cold frontal passage during the day and the direction of the post-frontal winds.

KEY MESSAGE 3: A cold front will bring low end rain chances Sunday, followed by a brief cooldown early next week.

Upper level trough and sfc cold front will move in tandem across the central CONUS Saturday, before pushing into the Carolinas by Sunday. While the latest forecast has maintained a 20-30% chance of PoPs for portions of our area, do want to emphasize that there will still be a lot of dry air in the mid to lower levels to contend with. Thus, overall probabilities for seeing >0.10" remain less the 25%. With rain chances remaining minimal throughout the rest of the extended period, will unfortunately continue to see drought conditions persist and likely worsen. Otherwise, look for a brief, but notable cool down to occur in the wake of FROPA Monday and Tuesday as highs dip back into the 70s. Lows in the upper 40s to lower 50s will also be common during this time. Temperatures then moderate back into the 80s by mid-week.

AVIATION /18Z FRIDAY THROUGH WEDNESDAY/

KCHS/KJZI/KSAV: VFR continues across the area. Outside of brief period of breezy winds along the sea breeze this afternoon, should see light winds persist throughout the period.

Extended Aviation Outlook: Elevated wind gusts are possible Sunday night into Monday morning.

MARINE

Outside of some breezy winds this afternoon along the sea breeze, should see light winds prevail across the waters this evening.

Otherwise, quiet marine conditions will persist into Saturday with the region remaining along the western flanks of Atlantic high pressure centered well offshore. Sea breeze enhancements along the land/sea interface and Charleston Harbor are likely each afternoon/evening.

A strong cold front is poised to push through the waters Sunday afternoon with winds quickly ramping up Sunday night into Monday morning in response to post-frontal cold air advection and a rapid tightening of the pressure gradient. North to northeast winds of 20- 30 kt are likely with gusts approaching gale force, especially over the 20-60 NM offshore zones. Seas look to peak Monday, ranging from 4-6 ft nearshore waters to 7-10 ft over the offshore waters (highest offshore Georgia waters). Small Craft Advisories are likely and a Gale Watch/Warning could be needed over the offshore zones.

Rip Currents: A Moderate Risk of rip currents remains in place for all beaches through Saturday due to the combination of 2-3 ft swell around 10 seconds, modest onshore flow, and increasing astronomical influences associated with lunar perigee/new moon. An elevated risk for rip currents will likely persist through the weekend and especially early next week as a pinched gradient associated with a passing cold front supports a gusty northeast wind event along the Southeast Coast.

CLIMATE

Record High Temperatures:

April 17: KCHS: 91/1967 KCXM: 86/2006 KSAV: 95/1967

April 18: KCHS: 92/1967 KSAV: 93/1967

CHS WATCHES/WARNINGS/ADVISORIES

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