textproduct: Charleston

WHAT HAS CHANGED

The Aviation Section was updated to reflect the 12Z TAFs.

KEY MESSAGES

- 1) Hot and humid conditions are expected across the area this weekend and through early next week.

DISCUSSION

KEY MESSAGE 1: Hot and humid conditions are expected across the area this weekend and through early next week. Very little change in the forecast is expect the next couple of days as the heat and humidity lingers through Wednesday. The overall players remain the same across the area with deep upper troughing across the Northeast, high pressure to our east over the Atlantic and a pesky tropical disturbance over the northern Gulf. Temperatures yesterday did not go entirely as plan and as dewpoints were able to mix and temperatures did not quite increase as high as we were expecting. This was likely due to a tightening gradient across the area leading to increased winds allowing for better mixing. As a result most areas fell short of advisory criteria. Looking ahead to Sunday and Monday, similar conditions are expected given the slowly organizing system over the Gulf and the upper trough slowly drifting eastward. This will likely result in highs topping out more in the low to maybe mid 90s and dewpoints able to mix out into the low 70s. This should be enough to keep heat indices in the 100 to 105 range and while this is still hot, this is more in line with normal summertime for the area. The bigger questions come on Wednesday as dewpoints should gradually increase as better moisture arrives. This will be aided by our disturbance in the Gulf as it slowly tracks westward. The usual trouble areas behind the seabreeze could start to approach advisory criteria come Tuesday into Wednesday as dewpoints climb into the upper 70s to near 80 resulting in heat indices of around 108 to 110.

There is some good news in that by the end of the week the upper trough will finally be able to move into the area leading to increased rain chances and at least a brief end to the heat.

AVIATION /12Z SUNDAY THROUGH THURSDAY/

12Z TAFs: VFR conditions will prevail KCHS/KJZI/KSAV through the period. Light southwesterly flow should strengthen this afternoon as the seabreeze shifts inland between 16-18Z for KCHS/KJZI and ~20Z for KSAV. Winds will become more southerly behind the seabreeze with frequent gusts to around 20 knots mainly along the coast. Gusts should subside shortly after 00z with winds slowly relaxing and turning southwesterly around 06z.

Extended Aviation Outlook: Predominately VFR conditions through the period, however there is a low chance of brief flight restrictions each afternoon from showers and thunderstorms developing along the seabreeze.

MARINE

Today: As the local waters remain situated between an inland trough and a subtropical high to the east, this will yield breezy southwesterly flow through late tonight. Expect wind speeds to range from 15 to 20 kts with gusts up to 25 kts (esp. across the nearshore Charleston waters). Thus, a Small Craft Advisory (SCA) remains in effect for the nearshore Charleston waters through Monday 06Z (2AM). As south-southwesterly swell slowly tapers back, expect seas to range from 3 to 4 ft throughout the day.

Monday through Thursday: This aforementioned inland trough will slowly shift offshore through the mid-week, allowing for another possible round of SCAs (esp. in the South Carolina nearshore waters). The National Hurricane Center (NHC) continues to monitor a system in the northeastern Gulf for possible tropical development, with a 60% chance of development in the next 7 days. If this system were to develop and track up the SE coastline there would be additional wind and wave concerns across the marine waters.

Rip Currents: There is Moderate Risk of rip currents for all beaches, given the 3 to 4 ft swell with wave periods up to 6 seconds. In addition, south-southwesterly winds will likely generate a moderate longshore current, possibly supporting rip currents near piers and jetties.

CLIMATE

Record High Minimum Temperatures:

July 18: KCHS: 79/2007 KCXM: 81/2007

July 19: KCHS: 79/1986 KCXM: 83/1986

July 20: KCHS: 79/2025 KCXM: 83/2000 KSAV: 79/1942

July 21: KCHS: 80/1986 KCXM: 83/1998

July 22: KCHS: 81/2011 KCXM: 83/2011

CHS WATCHES/WARNINGS/ADVISORIES

GA...None. SC...None. MARINE...Small Craft Advisory until 8 PM EDT this evening for AMZ360.