textproduct: Charleston

WHAT HAS CHANGED

All sections updated.

KEY MESSAGES

- 1) Heavy rainfall remains a threat through the rest of today. Thereafter, rain chances will slowly dwindle into the end of the week.

-2) Hot and humid conditions will return Wednesday and persist into the weekend.

DISCUSSION

KEY MESSAGE 1: Heavy rainfall remains a threat through the rest of today. Thereafter, rain chances will slowly dwindle into the end of the week.

Rest of Today: Little change to the synoptic pattern today from that observed yesterday. Mid-level troughing dominates aloft while a stationary front remains positioned in the vicinity of the local forecast area. With these two features influencing the region scattered thunderstorms are forecast this afternoon. PWATs remain quite high, as shown through the 12Z KCHS RAOB Sounding (2.2" PWAT) and the SPC mesoanalysis analyzing 2.3" as of 17Z. The KCLX radar shows a pronounced sea breeze as of 17Z, extending from southern Berkeley County southwestward into southern Charleston County. Over the next few hours this feature will be the highlight of precipitation. The morning time convection over southeastern Georgia likely overturned the atmosphere, limiting how much additional convection is able to get going. Additionally, the thick cloud cover across the region this afternoon will likely limit convection. However, the threat of heavy rainfall cannot be completely ruled out. Earlier this morning a storm on Tybee Island, GA dropped ~5" in about 3 hours. Any storm that is able to form will likely be a very efficient rainmaker and could pose a heavy rainfall risk.

Rest of this Week: The troughing in the mid levels will begin to break down tomorrow while mid level ridging builds into the area through the remainder of the week. As the ridging slowly builds precipitation chances will slowly dwindle each day, with PoPs only around 15% by Friday afternoon.

KEY MESSAGE 2: Its appearing like summer heat will try to make a final stand by the end of the week as high pressure over the central US flattens out and slowly extends across the Mid- Atlantic. We look to be on the southern Periphery of this ridge and with ample subsidence a loft, drier conditions are expected to return across the area mid to late week. Unfortunately with the drier conditions comes hotter temperatures as highs will likely climb back into the mid to upper 90s. with all the sunshine. Looking at some of the ensemble guidance and the ECMWF extreme forecast index (EFI), this heat does not look to pack the same punch as our heat wave earlier in the summer given our position with respect to the ridge. Overall conditions are leaning a little above normal climatology which is expected from a stout ridge; however, there remains a decent amount of uncertainty within the guidance on the strength of the ride especially Thursday through Saturday. IF the ridge ends up trending a little stronger then we could certainly see things trend a little warmer than we currently have it and the potential for heat products would also increase. Nonetheless, it does appear likely for our heat indices to climb back into the 105 to 110 range with the hottest days likely Friday and Saturday and would not be shocked if a heat advisory or two may be needed late week but plenty of time to monitor.

AVIATION /18Z SUNDAY THROUGH FRIDAY/

Another low confidence forecast for the 18Z TAFs at KCHS/KJZI/KSAV. Showers could impact KCHS/KJZI over the next few hours before drying out for the remainder of the 18Z TAF period. KSAV will likely remain dry through the afternoon and into the evening. A PROB30 group has been introduced to address the threat of shower/storm development early Monday morning along the southeastern GA coastline.

Extended Aviation Outlook: Periodic flight restrictions are expected in showers and thunderstorms through the first half of the week before more IFR conditions prevail late week.

MARINE

Through Tonight: E/NE winds will redevelop again tonight. Speeds look to remain less than 15 kt (outside of convection) with seas 2-3 ft. Another round of convection could develop across the GA waters early Monday morning.

Monday night through Saturday: No marine concerns expected. Light and variable prevailing flow will shift onshore each afternoon as the sea breeze circulation develops along the coast, with 2-3 ft seas.

CHS WATCHES/WARNINGS/ADVISORIES

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