641
FXUS62 KCHS 181843
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
243 PM EDT SAT JUL 18 2026
WHAT HAS CHANGED
ALL SECTIONS HAVE BEEN UPDATED.
KEY MESSAGES
- 1) HOT AND HUMID CONDITIONS ARE EXPECTED ACROSS THE AREA THIS
WEEKEND AND THROUGH EARLY NEXT WEEK. HEAT ADVISORIES CONTINUE
FOR THIS AFTERNOON AND ADDITIONAL HEAT ADVISORIES COULD BE
NEEDED.
DISCUSSION
KEY MESSAGE 1: HOT AND HUMID CONDITIONS ARE EXPECTED ACROSS THE
AREA THIS WEEKEND AND THROUGH EARLY NEXT WEEK. HEAT ADVISORIES
CONTINUE FOR THIS AFTERNOON AND ADDITIONAL HEAT ADVISORIES COULD
BE NEEDED.
ISOLATED SHOWERS AND THUNDERSTORMS HAVE BEGUN TO DEVELOP ACROSS
THE AREA, LIMITED ONLY BY THE H5 592 DM RIDGE IN PLACE ALOFT.
THIS HAS HELPED TEMPERATURES ACROSS MOST PLACES CLIMB TO THE MID
90S SO FAR TODAY. DEW POINTS WELL INTO THE 70S HAVE RESULTED IN
HEAT INDICES 100+, WITH SOME SPOTS ALONG THE COAST ALREADY
ABOVE 108F. LITTLE COOLING RELIEF IS EXPECTED THROUGH THE
EVENING WITH NOT MUCH IN THE WAY OF CONVECTIVE COVERAGE THIS
AFTERNOON. CURRENT HEAT ADVISORIES IN EFFECT ACROSS SOUTHEAST
SOUTH CAROLINA AND SOUTHEAST GEORGIA WILL CONTINUE UNTIL 8 PM
TONIGHT.
SUNDAY AND MONDAY WILL SEE LITTLE CHANGE IN THE SYNOPTIC SET UP,
WITH LOW PRESSURE IN THE NORTHERN GULF AND HIGH PRESSURE POSITIONED
OVER THE WESTERN ATLANTIC. THIS CONTINUED SET UP WILL ALLOW
TEMPERATURES TO REACH INTO THE LOW TO MID 90S EACH DAY, WITH HEAT
INDEX VALUES AROUND 100-105. THE CURRENT FORECAST KEEPS HEAT INDEX
VALUES JUST SHY OF HEAT ADVISORY CRITERIA (>108), HOWEVER HEAT
ADVISORIES CANNOT BE RULED OUT, ESPECIALLY ALONG THE COASTAL
CORRIDOR WHERE THE DEW POINTS WILL BE HIGHEST. THE PATTERN WILL
BEGIN TO SHIFT ON TUESDAY AS AN UPPER LEVEL TROUGH SWINGS EASTWARD.
THIS WILL YIELD GREATER COVERAGE OF AFTERNOON SHOWERS/THUNDERSTORMS
AND LIMIT THE HEAT POTENTIAL EACH AFTERNOON.
AVIATION /18Z SATURDAY THROUGH THURSDAY/
18/18Z TAFS: ISOLATED SHOWERS AND THUNDERSTORMS WILL CONTINUE
TO DEVELOP THIS AFTERNOON INTO THE EVENING, INITIATING ALONG THE
SEA BREEZE. THE BEST CHANCE FOR A STORM TO HAVE IMPACTS ON ANY
OF THE TERMINALS LOOKS TO BE ACROSS SOUTHEAST GEORGIA
POTENTIALLY NEAR KSAV PRIOR TO SUNSET. HOWEVER, DUE TO THEIR
ISOLATED NATURE, WE KEEP THE MENTION OF PROB30. GUSTY SOUTHERLY
WINDS WILL ACCOMPANY THE SEA BREEZE THIS AFTERNOON, BEFORE
BECOMING LIGHTER LATE THIS EVENING, AND RAMPING UP AGAIN SUNDAY
AFTERNOON. OTHERWISE, WE ANTICIPATE VFR CONDITIONS TO PREVAIL
THROUGH 18Z SUNDAY.
EXTENDED AVIATION OUTLOOK: PREDOMINATELY VFR CONDITIONS THROUGH
THE PERIOD, HOWEVER THERE IS A LOW CHANCE OF BRIEF FLIGHT
RESTRICTIONS EACH AFTERNOON FROM SHOWERS AND THUNDERSTORMS
DEVELOPING ALONG THE SEABREEZE.
MARINE
TODAY AND TONIGHT: AS THE LOCAL WATERS SITUATE BETWEEN AN
INLAND TROUGH AND A SUBTROPICAL HIGH TO THE EAST, THIS WILL
ALLOW FOR THE PRESSURE GRADIENT TO STRENGTHEN THROUGHOUT THE
DAY. EXPECT WIND SPEEDS TO RANGE FROM 15 TO 20 KTS WITH GUSTS UP
TO 25 KTS (ESPECIALLY ACROSS THE CHARLESTON COUNTY NEARSHORE
WATERS). THUS, SMALL CRAFT ADVISORIES HAS BEEN ISSUED FOR THE
NEARSHORE SOUTH CAROLINA WATERS FROM 0-20 NM (NOT INCLUDING THE
CHARLESTON HARBOR) STARTING AT 8 PM AND INTO TONIGHT. SHOULD
SEE A SLIGHT DOWNTREND IN WIND SPEEDS LATE TONIGHT, WITH WINDS
RAMPING DOWN JUST PRIOR TO SUNRISE SUNDAY. EXPECT SEAS TO RANGE
FROM 2 TO 3 FT, BEFORE INCREASING TO 3 TO 5 FT TONIGHT.
SUNDAY THROUGH WEDNESDAY: THE MARINE WATERS WILL REMAIN POSITIONED
BETWEEN HIGH PRESSURE TO THE EAST AND LOW PRESSURE IN THE NORTHERN
GULF INTO EARLY NEXT WEEK. THIS WILL YIELD A PINCHED PRESSURE
GRADIENT AND SW WINDS GUSTING AROUND 20 KNOTS. SUNDAY WILL SEE GUSTS
AS HIGH AS 25 KNOTS ACROSS THE CHARLESTON NEARSHORE WATERS. A SMALL
CRAFT ADVISORY IS IN EFFECT FOR THIS MARINE ZONE THROUGH SUNDAY
EVENING. MID WEEK A TROUGH INLAND WILL SHIFT OFFSHORE AND AGAIN
ENHANCE THE WIND GUSTS. SMALL CRAFT ADVISORIES COULD BE NEEDED MID-
WEEK, ESPECIALLY IN THE CHARLESTON NEARSHORE WATERS AND THE
CHARLESTON HARBOR. THE NATIONAL HURRICANE CENTER IS MONITORING A
SYSTEM IN THE NORTHERN GULF FOR POSSIBLE TROPICAL DEVELOPMENT, WITH
A 40% CHANCE OF DEVELOPMENT IN THE NEXT 7 DAYS. IF THIS SYSTEM WERE
TO DEVELOP AND TRACK UP THE SE COASTLINE THERE WOULD BE ADDITIONAL
WIND AND WAVE CONCERNS ACROSS THE MARINE WATERS.
RIP CURRENTS: THE PINCHED GRADIENT ACROSS THE MARINE ZONES WILL
YIELD SW WIND GUSTS AROUND 20 KNOTS. DUE TO THE ENHANCED WINDS ALONG
THE COASTLINE THERE IS A MODERATE RISK OF RIP CURRENTS AT ALL AREA
BEACHES TOMORROW (SUNDAY).
CLIMATE
RECORD HIGH MINIMUM TEMPERATURES:
JULY 18:
KCHS: 79/2007
KCXM: 81/2007
JULY 19:
KCHS: 79/1986
KCXM: 83/1986
JULY 20:
KCHS: 79/2025
KCXM: 83/2000
KSAV: 79/1942
JULY 21:
KCHS: 80/1986
KCXM: 83/1998
JULY 22:
KCHS: 81/2011
KCXM: 83/2011
CHS WATCHES/WARNINGS/ADVISORIES
GA...HEAT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR GAZ087-088-
099>101-114-115-137-216>219-238>241.
SC...HEAT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR SCZ040-042>045-
147>152.
MARINE...SMALL CRAFT ADVISORY FROM 8 PM THIS EVENING TO 8 PM EDT SUNDAY
FOR AMZ360.
SMALL CRAFT ADVISORY FROM 8 PM THIS EVENING TO 6 AM EDT SUNDAY
FOR AMZ362.
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