textproduct: Charleston

WHAT HAS CHANGED

Aviation section updated to represent 12Z forecast.

KEY MESSAGES

- 1) Increased showers and storms will possible through today capable of producing locally heavy rainfall.

DISCUSSION

KEY MESSAGE 1: Increased showers and storms will possible through today capable of producing locally heavy rainfall.

A rather large upper trough centered over the Great Lakes will continue its slow drift east today into Sunday as several embedded shortwaves pivot through the broader flow. At the surface our slow moving front will encroach on the coastal areas by this afternoon and likely be the focus for afternoon showers and thunderstorms. The first shortwave is currently moving across the area right now will some scattered showers and storms occurring across the coastal areas and offshore waters. This shortwave should move out of the area by daybreak setting the stage for the afternoon. The final shortwave should swing into the area by mid-afternoon resulting in scattered to numerous showers and thunderstorms likely beginning east of I-95 and closer to the coastline than yesterday. Overall severe threat looks minimal with these storms with rather poor surface heating (high temperatures in the upper 80s to low 90s) coupled with rather deep moist profiles with PWATs approaching 2.1 to 2.2 inches. While a strong wind gust cannot be ruled out the overall potential should be rather muted compared to say yesterday. The bigger issue may become heavy rainfall. Given the aforementioned moisture profiles, coupled with weak deep layer flow, storms will be rather efficient rain producers and some localized heavy rainfall certainly cannot be ruled out. This is backed by some of the high-res ensemble guidance which supports some 3 hourly totals in the 2 to 4 inch range. For most of the area these totals won't be too much of an issue, there could be a focus along and near the coastal cities that tend to not handle heavy rain rates as well as interior areas. We will certainly have to see how things go this afternoon, but would not be surprised if a few spots might see some localized minor flooding.

Sunday Onward: The aforementioned upper trough will finally move far enough east to usher in some drier air into the area by Sunday into Monday. With drier air in place and the surface boundary pushed offshore, rain chances should remain low through Monday. However, moisture should begin to recover starting Tuesday and into the middle of the week with a return to more typical summertime pattern setting up.

AVIATION /12Z SATURDAY THROUGH WEDNESDAY/

22/06z TAFs: A narrow band of IFR to LIFR ceilings have developed along the immediate coastline and will impact JZI for the next hour or two before VFR conditions return area wide. Winds will be light out of the southwest throughout the day. Scattered to numerous thunderstorms should develop along the coastline this afternoon possibly resulting in temporary reductions at all area terminals. Storms look most likely near CHS/JZI before subsiding during the early evening. VFR conditions should return overnight with light southwesterly winds.

Extended Aviation Outlook: Thunderstorms will again be a concern Saturday afternoon and evening. Otherwise, VFR conditions will prevail.

MARINE

Today through Thursday: Marine conditions are expected to remain below Small Craft Advisory criteria through the period. A fairly typical summertime pattern on tap. Generally expect south to southwest winds averaging in the 10-15 knot range with gusts to 20 kt at times and seas 2 to 3 feet. Any showers or thunderstorms that move over the waters have the potential to bring higher wind gusts and frequent lightning.

CLIMATE

Record High Minimum Temperatures:

August 24: KCHS: 76/2010 KCXM: 80/1975

August 25: KCHS: 77/1982

August 27: KCHS: 78/2011

August 28: KCHS: 77/2020

CHS WATCHES/WARNINGS/ADVISORIES

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