textproduct: Charleston

WHAT HAS CHANGED

All Key Messages and sections were updated.

KEY MESSAGES

- 1) Record high temperatures possible this afternoon.

- 2) Cooler temperatures Tuesday and Wednesday, followed by rising temperatures Thursday into the weekend. Increasing rain chances late this week.

- 3) Minor coastal flooding possible with the Tuesday midday high tide along coastal portions of Charleston and Colleton Counties.

DISCUSSION

KEY MESSAGE 1: Record high temperatures possible this afternoon.

Temperatures are on target to peak near record levels this afternoon. The record high (94) for the date as already been tied at the Charleston International Airport and has a solid chance of falling over the next few hours. The record high at the Savannah International Airport will also be challenged. The record for Downtown Charleston looks safe. Dewpoints pooling into the mid-upper 70s near the late afternoon sea breeze could yield heat indices 104-107 range. A few spots could possibly briefly reach 108-109 before cooler air behind the sea breeze filters in. Spatial limitations and short temporal durations suggest a Heat Advisory is not needed. A isolated shower or tstm could pop just along/ahead of the sea breeze as well, but coverage too limited to include a mentionable pop at this time.

KEY MESSAGE 2: Cooler temperatures Tuesday and Wednesday, followed by rising temperatures Thursday into the weekend. Increasing rain chances late this week.

As a cold front shifts southward across the Carolinas tonight, northeasterly flow will usher in slightly cooler temperatures into the region on Tuesday and Wednesday. Expect afternoon highs on Tuesday to reach into the upper 80s to low 90s, with Wednesday being slightly cooler with afternoon highs in the mid to upper 80s. There is a chance of a couple isolated showers developing in the early afternoon on Tuesday, however activity should dissipate as drier air advects into the area as high pressure builds in from the north. Wednesday will be the driest day of the week with afternoon dewpoints dipping into the upper 50s to low 60s across the inland areas with low to mid 60s near the coastline.

As this aforementioned high starts to shift offshore on Thursday and Friday, afternoon highs will trend upwards through the weekend. Along with this, chances for rain will increase as well through the weekend.

KEY MESSAGE 3: Minor coastal flooding possible with the Tuesday midday high tide along coastal portions of Charleston and Colleton Counties.

Minor coastal flooding is possible with the Tuesday late morning high tide along the Charleston and Colleton County coasts. Strengthening northeast winds are expected on Tuesday, which will increase tidal departures. The tide would need ~1 ft departure to reach minor flooding thresholds of 7 ft MLLW in the Charleston Harbor and most guidance indicates this could be achieved with levels peaking in the 7.0-7.2 ft MLLW range. A Coastal Flood Advisory could be needed. No issues are expected further south along the far southern South Carolina and Georgia coasts.

AVIATION /18Z MONDAY THROUGH SATURDAY/

14/18z TAFs: KCHS/KJZI/KSAV: VFR through 15/18z. A rogue shower or tstm could pop along the sea breeze this afternoon, but impact probabilities to any of the terminals look too low to justify a mention. Gusty northeast winds will impact all terminals beginning as early as sunrise at KCHS and KJZI and mid-morning at KSAV.

Extended Aviation Outlook: Prevailing VFR conditions with the chance of breezy northeasterly winds (gusts up to 20 kts possible) on Wednesday and Thursday afternoons. Otherwise, it will be fairly dry until Friday when rain chances increase again.

MARINE

Tonight: A backdoor cold front will drop south into the waters tonight. Both winds and seas look to remain below Small Craft Advisory levels until closer to daybreak, except possibly the South Santee-Edisto Beach nearshore leg where frequent gusts to 25 kt look increasingly likely after about 5-6 AM.

Tuesday through Friday: A cold front will remain located south of the waters on early Tuesday morning, while high pressure continues to build in from the north. Northeasterly winds will quickly ramp up on Tuesday morning with speeds ranging from 15-20 kts with gusts up to 30-32 kts across all the marine zones. It'll get close to gales across the Georgia waters and we'll continue to monitor this in the forecast. Small Craft Advisories have been issued across the nearshore and offshore Georgia waters for Tuesday morning and lasting well into Thursday evening. This strong onshore flow will drive seas to surge to 4-7 ft throughout much of the period, before decreasing to 3-5 ft overnight on Thursday into Friday morning. More favorable marine conditions are expected on Friday as winds fall to around 5-10 kt and seas continue to lower. Mariners should continue to monitor the latest forecast before heading offshore.

Rip Currents: The combination of breezy northeasterly winds with elevated seas Tuesday into mid-week will lead to an elevated risk of rip currents. There is a High Risk of rip currents for the Georgia beaches tomorrow (9/15) and a Moderate Risk for the South Carolina beaches. Beachgoers should swim near a lifeguard and heed local beach patrol guidance.

A High Risk of rip currents is expected along the Georgia beaches on Wednesday (9/16) with a Moderate Risk along the South Carolina beaches.

CLIMATE

Record High Temperatures:

September 14: KCHS: 94/1991 KCXM: 94/1938 KSAV: 96/1991

CHS WATCHES/WARNINGS/ADVISORIES

GA...High Risk for Rip Currents from Tuesday morning through Tuesday evening for GAZ217-219-239-241. SC...None. MARINE...Small Craft Advisory from 6 AM Tuesday to 8 PM EDT Thursday for AMZ360. Small Craft Advisory from 8 AM Tuesday to 8 PM EDT Thursday for AMZ362. Small Craft Advisory from 11 AM Tuesday to midnight EDT Thursday night for AMZ364-384.