textproduct: Charleston

WHAT HAS CHANGED

Aviation section has been updated.

KEY MESSAGES

- 1) Periodic showers and thunderstorms expected to continue this week within a persistent summertime pattern.

DISCUSSION

KEY MESSAGE 1: Periodic showers and thunderstorms expected to continue this week within a persistent summertime pattern.

Today and Tonight: A weak cold front will continue to work its way into the region through the morning hours, with broad upper level troughing sending scattered short-waves across the area. With precipitable water values surging to just above 2 inches, the aforementioned forcing will lead to scattered showers and isolated thunderstorms, increasing in areal coverage into the daylight hours. Shower/storm intensity will build into the afternoon as weak instability builds, though storms will continue to remain mostly scattered in nature. While 30-40 knots of shear returns to the region, SBCAPE looks to largely remain below 1000 J/kg, and with 700- 500mb lapse rates looking to be only 5 deg C/km, the risk for severe thunderstorms is low but non-zero. Rainfall amounts will remain on the lighter side due to 500mb winds in the 30-40 knot range, though areas that see multiple rounds of rain have a 30% probability for seeing an inch of rain by early morning Wednesday.

Given the increase in cloud coverage and chances for rain from the aforementioned cold front, temperatures will be much cooler today. Afternoon highs across far inland southeast South Carolina and southeast Georgia may struggle to get into the 80s, while areas along the coast look to still reach up into the mid to upper 80s. In addition, the surface pressure gradient will be increased today, leading to marginally breezy west-southwesterly winds. Chances for showers/storms continue into the overnight period, with overnight lows in the mid 60s inland and up into the mid 70s along the coast.

Wednesday - Friday: Decent convective coverage is possible Wednesday morning as lingering shortwave energy moves through, then shortwave ridging should bring a lull in convection for the afternoon. A surge in low-level moisture combined with potent shortwave energy should result in numerous to widespread showers and tstms Thursday through Friday.

AVIATION /12Z TUESDAY THROUGH SATURDAY/

12Z TAFs: Scattered showers expected to continue moving into the region from the southwest throughout the morning hours, with MVFR- IFR cigs lagging behind but will also be moving into the area this afternoon. Expect mostly showers in the early morning hours, with isolated thunderstorms increasing as instability builds mostly across southeastern Georgia into the evening hours. Have thus not included any mention of thunder at KCHS and KJZI, but did include it for the KSAV terminal. Latest guidance would indicate brief VFR cigs later this afternoon, returning back to MVFR-IFR during the evening/overnight hours.Extended Aviation Outlook: VFR conditions should mostly prevail through the weekend, with brief periods of flight restrictions possible due to afternoon showers and thunderstorms throughout the week.

MARINE

The local waters will sit between Atlantic high pressure to the east and a surface trough inland for much of the week. This will drive moderate southwest flow of 15-20 knots through most of the period, though wind gusts in excess of 25 knots are possible tonight as the surface pressure gradient tightens into the overnight hours. High resolution guidance is not as convinced, so have held off on issuing with this package. After weakening Wednesday morning, the pressure gradient again tightens overnight into Thursday, though it looks to be below advisory criteria at this time. The highest chance of needing Small Craft Advisories will come Friday as the pressure gradient tightens ahead of an approaching front.

CLIMATE

Record High Minimum Temperatures:

June 18 KCHS: 78/2015 KCXM: 81/1998

June 19 KCHS: 79/2025 KCXM: 81/2025 KSAV: 79/1881

June 22: KCHS: 79/2018 KSAV: 78/1937

CHS WATCHES/WARNINGS/ADVISORIES

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