textproduct: Charleston

WHAT HAS CHANGED

Aviation section.

KEY MESSAGES

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

DISCUSSION

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

Through tonight: Aloft, the pattern will continue to feature broadly cyclonic flow with subtle shortwave energy passing through at times. At the surface, analysis shows that a weak boundary still sits inland across central GA and the SC Midlands. There is plenty of moisture across the region, with precipitable water values ranging from around 1.75 inches across northern Berkeley County to 2+ inches along the Altamaha. Plentiful cloud cover will continue to stream across the area within the southwest flow, and this will keep temperatures below normal. In fact, some locations across interior southeast GA/SC might not reach 80. The best chance for some partial clearing and warming into the mid to upper 80s will be south of I-16 and along the GA coast.

This cloud cover and resulting temperatures will also work to keep instability from reaching typical summertime levels. In fact, MLCAPE values will likely only get up to 1,000 J/kg in the aforementioned areas south of I-16 where the best surface heating will be. So while we will likely continue to see showers and areas of light rain just about everywhere, the only real thunderstorm risk is across the southern tier. There is some 30-40 knot mid-level flow noted in model soundings, yielding around 30 knots of effective shear. This combination of instability and shear across the southern tier could produce a low end severe threat for the afternoon and evening hours. Therefore it follows that this area remains within SPC's Day 1 Severe Weather Outlook Marginal Risk area, primarily for damaging wind gusts. The potential for thunderstorms will persist through the evening and possibly even into the early morning hours.

Wednesday - Friday: A lingering shortwave will result in continued chances for showers and storms Wednesday morning and afternoon, with a lull in activity likely heading into the late afternoon. Overall severe threat looks to remain low, so outside of a few rumbles of thunder, expect brief heavy downpours and frequent lightning to be the primary impacts. In regard to temperatures, have afternoon highs remaining near/slightly below normal (mid to upper 80s) under cloudy skies.

Should see largely dry conditions prevail Wednesday night into Thursday morning, before another round of precipitation begins Thursday afternoon. As noted in the previous discussion, will see a decent surge of Gulf moisture surge overhead the region during this time, which will result in numerous to widespread showers and thunderstorms through Friday. While the severe threat remains fairly meager, can't rule out seeing an isolated storm or two becoming strong to severe on Friday as instability increases ahead of an advancing cold front.

Saturday - Sunday: Typical summertime pattern will persist into the weekend, with daily chances for diurnally driven showers and storms. That being said, do want to point out that coverage should be much less than Thursday and Friday. Otherwise, look for highs to gradually warm back into the lower 90s by Sunday.

AVIATION /06Z WEDNESDAY THROUGH SUNDAY/

Occasional light rain will continue overnight, then the best upper forcing will move offshore Wednesday morning. Although there remains a chance for brief MVFR ceilings overnight, the models have backed off on the probability, and we removed mention from the 06Z TAFs. Convective coverage on Wednesday looks fairly low, but the greatest chance will be at KSAV. Gusty SW winds expected to develop by mid-morning.

Extended Aviation Outlook: VFR conditions should largely prevail through the weekend, with brief periods of flight restrictions possible with any shower and thunderstorm throughout the week.

MARINE

Through Tonight: West-southwest to southwest flow will continue across the local waters. The pressure gradient is expected to enhance a bit this evening and overnight. Wind speeds are expected to increase into the 15-20 knot range, with some potential for gusts up to around 25 knots at times across the SC waters and maybe the outer GA waters. Seas will rise in response to the stronger winds, becoming 3-4 feet overnight with potential for up to 5 feet in the SC waters. Current thinking is that overall conditions will remain just below Small Craft Advisory thresholds.

Wednesday Onward: Breezy southeasterly winds look to prevail across our waters through Friday before gradually tapering off over the weekend. As noted in the previous discussion, the next best chance for needed any Small Craft Advisories will be Friday as the pressure gradient tightens ahead of an advancing front. Gusts between 25 to 35 kts and seas between 4 to 8 ft will become common during this time.

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.