textproduct: Charleston

WHAT HAS CHANGED

The Aviation section was updated for the 00z TAF issuance.

KEY MESSAGES

- 1) Below normal rain chances through Friday with increasing rain chances over the weekend.

- 2) Patchy to areas of fog will be possible tonight with some dense fog possible.

- 3) Hot and humid conditions expected into the upcoming weekend.

DISCUSSION

KEY MESSAGE 1: Below normal rain chances through Friday with increasing rain chances over the weekend.

Wednesday: Mostly dry conditions will prevail through Wednesday as the broad upper ridging builds over the area. Based off 12z sounding data, the subsidence inversion has not quite built over the area but it has show up over interior part of south Carolina and Georgia. However, the profile even today remains rather dry and should continue to dry out as subsidence builds eastward. As a result, there should not be much in the way of clouds let along rain tomorrow.

Thursday through Labor Day: High pressure should become centered over the Carolinas by the end of the week. This will keep a fairly hot, dry and subsident environment in place with a progressive resultant sea breeze likely to occur each afternoon. There may be just enough moisture return along southwest flanks of the surface high pressure centered well offshore to allow for isolated to perhaps scattered showers/tstms to develop by Thursday and Friday across southeastern Georgia. However, much will depend on exactly where the center of the upper high becomes situated. Rain chances will increase over the Labor Day holiday weekend as the upper ridge breaks down in response to broad troughing developing across the eastern CONUS. This system should push a cold front into the area and possibly drops southward through the Southeast States with shower and storms focused along this advancing boundary.

KEY MESSAGE 2: Patchy to areas of fog will be possible tonight with some dense fog possible.

With high pressure building over the area and sufficient residual low level moisture we should see another night of potential low stratus and fog. Guidance continues to be a bit mixed with fog coverage and density but with very little airmass change, the forecast is a bit of persistence given the stratus build down we saw this morning. Some locations could even see a short-lived period of dense fog. We could eventually need a Special Weather Statement or even a Dense Fog Advisory.

KEY MESSAGE 3: Hot and humid conditions expected into the upcoming weekend.

Aloft, a ridge of high pressure will extend from the Midwest to the Mid-Atlantic/Southeast regions today, marking the beginning of a warming trend mid to late week. Today, the region will start to slide under the eastern periphery of the ridge, bringing widespread temperatures in the upper 80s to lower 90s, with heat index values in the upper 90s to lower 100s. On Wednesday, the ridge axis remains slightly north of the local area while weak h5 vort energy shifts onshore across the Southeast Coast late Wednesday and Thursday, which should maintain similar heat/humidity conditions with slightly higher chances of precip and clouds across southern areas mid-week. Heading into late week, a notable increase in ridging occurs aloft, supporting warmer temps into the low-mid 90s Friday, then mid 90s Saturday. These temps in combination with mid-upper 70 dewpts could support Heat Advisory conditions across the coastal corridor this weekend (highest chance Saturday), before a cold front arrives early next week.

AVIATION /00Z WEDNESDAY THROUGH SUNDAY/

The 00z TAF period begins with VFR conditions at KCHS, KJZI, and KSAV. The main forecast challenge again revolves around the potential for low stratus and fog at all 3 TAF sites. Model guidance is a bit mixed with the potential coverage and density of fog. But given that we saw a few hours of IFR conditions this morning, it seems likely we will see somewhat of a repeat given that the airmass hasn't really changed. We have maintained IFR conditions roughly in the 10-14z time period. Dense fog is possible, and could need to be added to the TAF's with future issuances.

Extended Aviation Outlook: Showers/thunderstorms could bring brief flight restrictions to the SAV terminal Thursday and Friday. Greater chances for flight restrictions with showers/thunderstorms arrive to all terminals Saturday with a passing cold front.

MARINE

Through tonight: Northeast winds will back more easterly at the coast this afternoon as the sea breeze forms and moves inland. East winds this evening will gradually back to the northeast again near the beaches late. Winds look to remain 10 kt or less through the period with seas 3 ft or less. Some patchy marine fog could be possible after midnight, especially across the immediate nearshore coastal waters and Charleston Harbor.

Wednesday through Sunday: High pressure north/offshore and weak coastal troughing positioned closer the Southeast Coast will support conditions well below Small Craft Advisory levels through mid week, although increasing chances for thunderstorms should occur across Georgia waters on Thursday. Outside this activity, onshore flow should peak between 10-15 kt daily with afternoon sea breeze circulations while seas range between 2-4 ft. Conditions should remain below Small Craft Advisory levels this weekend, but there should be a slight uptick in winds (15-20 kt) as a cold front approaches, then shifts across local waters. Seas remain between 1-3 ft during this timeframe.

Rip Currents: A modest east-northeast wind along with long period swells of 2.5 ft every 12 seconds supports a Moderate Risk of rip currents along Georgia beaches Wednesday.

CHS WATCHES/WARNINGS/ADVISORIES

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