448
FXUS62 KCHS 221023
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
623 AM EDT MON JUN 22 2026
WHAT HAS CHANGED
THE AVIATION SECTION WAS UPDATE TO REFLECT THE 12Z TAFS.
KEY MESSAGES
- 1) A FAIRLY TYPICAL SUMMERTIME PATTERN IS FORECAST WITH DAILY
SHOWER AND THUNDERSTORM CHANCES THROUGH THE WEEKEND.
DISCUSSION
KEY MESSAGE 1: A FAIRLY TYPICAL SUMMERTIME PATTERN IS FORECAST
WITH DAILY SHOWER AND THUNDERSTORM CHANCES THROUGH THE WEEKEND.
THROUGH TONIGHT, THE SYNOPTIC PATTERN HAS CHANGED LITTLE SINCE
SUNDAY WITH THE REGION STILL POSITIONED ALONG THE WESTERN FLANKS OF
ATLANTIC HIGH PRESSURE CENTERED WELL OFFSHORE. THE FLOW ALOFT WILL
BE BIT MORE WESTERLY COMPARED TO 24 HOURS AGO WHICH WILL TEND TO
KEEP THE SEA BREEZE PINNED TO THE IMMEDIATE COAST FOR MUCH OF THE
DAY WITH IT POSSIBLY BEGINNING A EXTREMELY SLOW INLAND TREK CLOSER
TO LATE AFTERNOON, ESPECIALLY ALONG THE LOWER SOUTH CAROLINA COAST.
WARM AND MOIST CONDITIONS WILL REMAIN PLACE TODAY WITH DEWPOINTS
LIKELY TO HOLD IN THE LOWER-MID 70S EXCEPT OVER PARTS OF THE
CHARLESTON TRI-COUNTY INTO COLLETON COUNTY WHERE THE MOISTURE DEPTH
IS A BIT MORE SHALLOW AND MORE VIGOROUS VERTICAL MIXING COULD ALLOW
DEWPOINTS TO MIX OUT IN THE UPPER 60S IN SPOTS. HIGHS ARE POISED TO
WARM INTO THE LOWER-MID 90S FOR MANY SPOTS WITH HEAT INDICES PEAKING
IN THE 100-106F RANGE WHICH IS BELOW THE LOCAL HEAT ADVISORY
CRITERIA OF 108F. SIMILAR TO YESTERDAY, THE AIRMASS WILL REMAIN
SUPPORTIVE OF PULSE CONVECTION IN THE ABSENCE OF ANY MEANINGFUL
SYNOPTIC FORCING MECHANISMS. THE CONVECTIVE PATTERN WILL LIKELY BE
AUGMENTED ON THE MESOSCALE AT TIMES WITH AN ISOLATED STRONG OR
SEVERE TSTM BECOMING POSSIBLE WHERE UPDRAFTS CAN BE LOCALLY ENHANCED
BY BOUNDARY COLLISIONS NEAR THE SEA BREEZE OR OTHER CONVECTIVE
OUTFLOWS. WIND GUSTS 40-60 MPH, FREQUENT CLOUD-TO-GROUND LIGHTNING
AND LOCALLY HEAVY RAINFALL WILL BE THE PRIMARY HAZARDS. POPS 20-30%
LOOK REASONABLE FOR MOST AREAS THIS AFTERNOON WITH CONVECTION
WINDING DOWN DURING THE EVENING HOURS. WILL HAVE TO WATCH FOR SOME
NOCTURNAL CONVECTION APPROACHING INTERIOR SOUTHEAST GEORGIA FROM THE
WEST CLOSER TO THE MIDNIGHT, BUT MOST OF THIS SHOULD DISSIPATE PRIOR
TO REACHING THIS FAR EAST AS DIURNAL INSTABILITY WANES.
A SOUTHWESTERLY FLOW AHEAD OF APPROACHING COLD FRONT WILL
LIKELY KEEP THE BOUNDARY WELL MIXED FOR MANY AREAS OVERNIGHT.
THIS WILL TEND TO KEEP TEMPERATURES UP THROUGH SUNRISE WITH LOWS
LIKELY ONLY BOTTOMING OUT IN THE LOWER-MID 70S WEST OF I-95
WITH UPPER 70S/NEAR 80 ELSEWHERE. THE RECORD HIGH MINIMUMS AT
ALL THREE CLIMATE SITES COULD BE CHALLENGED, ASSUMING CONVECTION
DURING THE DAY TUESDAY DOES NOT DRIVE TEMPERATURES BELOW RECORD
LEVELS PRIOR TO 1 AM WEDNESDAY. SEE THE CLIMATE SECTION BELOW
FOR ADDITIONAL DETAILS.
GUIDANCE SUGGESTS A WEAK COLD FRONT WILL MOVE TOWARD THE CAROLINA
COAST AND ACROSS CENTRAL GEORGIA TUESDAY AND THEN STALL, REMAINING
NEARLY THROUGH THE END OF THE WEEK. ISOLATED TO SCATTERED SHOWERS
AND THUNDERSTORMS ARE POSSIBLE TUESDAY, OWING TO THE FRONT IN THE
VICINITY. BUT DEEP WESTERLY FLOW ADVECTING DRIER AIR INTO THE AREA
WILL LIMIT CONVECTION. THEN A SEASONABLE COMBINATION OF OFFSHORE
RIDGING/INLAND TROUGHING REESTABLISHES THROUGH THE DAY WEDNESDAY AND
PERSISTS INTO THE WEEKEND, WITH WEAK SUBSIDENCE ALOFT MAINTAINING
MAINLY ISOLATED TO SCATTERED DIURNAL DAILY CONVECTION. A FEW
STRONGER STORMS ARE POSSIBLE EACH AFTERNOON, BUT THERE IS NO
APPARENT SIGNIFICANT SEVERE THREAT AT THIS TIME.
AVIATION /12Z MONDAY THROUGH FRIDAY/
22/12Z TAF DISCUSSION:
KCHS/KJZI/KSAV: IFR/MVFR CIGS SHOULD MIX OUT TO VFR BY 13-14Z.
VFR WILL THEN PREVAIL FOR THE REMAINDER OF THE 12Z TAF PERIOD.
ISOLATED SHOWER/TSTMS ARE EXPECTED THIS AFTERNOON. IMPACT
PROBABILITIES ARE TOO LOW TO JUSTIFY A MENTION OF TSRA AT ANY OF
THE TERMINALS AT THIS TIME.
EXTENDED AVIATION OUTLOOK: BRIEF FLIGHT RESTRICTIONS ARE POSSIBLE
WITH MAINLY AFTERNOON SHOWERS AND THUNDERSTORMS.
MARINE
TODAY: A BROAD SOUTHERLY FLOW REGIME WILL PERSIST ACROSS THE
WATERS TODAY AS HIGH PRESSURE HOLDS WELL OFFSHORE. A WESTERLY
FLOW ALOFT WILL DELAY THE DEVELOPMENT OF THE SEA BREEZE, BUT
ONE SHOULD EVENTUALLY DEVELOP, BUT REMAINED PINNED TO/NEAR THE
COAST UNTIL LATE. WEST WINDS 10-15 KT WILL BACK TO THE SOUTHWEST
LATER IN THE DAY, BUT INCREASE TO 15-20 KT WITH GUSTS TO 25 KT
ACROSS THE SOUTH SANTEE-EDISTO BEACH NEARSHORE AND OFFSHORE LEGS
LATER THIS AFTERNOON. SEAS WILL BUILD TO 2-4 FT.
TONIGHT: THE PATTERN LOOKS TO FAVOR A CLASSIC SUMMER NOCTURNAL
SURGE TONIGHT AS HIGH PRESSURE REMAINS WELL OFFSHORE AND A COLD
FRONT APPROACHES FROM THE NORTHWEST. THE HIGHEST OVERNIGHT WINDS
LOOK TO CENTER ACROSS THE SOUTH CAROLINA NEARSHORE AND OFFSHORE
WATERS WITH THE RISK FOR REACHING FREQUENT GUSTS 25-30 KT
PEAKING OVER THE SOUTH SANTEE-EDISTO BEACH NEARSHORE AND
OFFSHORE LEGS. HREF PROBABILITIES FOR FREQUENT GUSTS >25 KT
SURGE AS HIGH AS 30-65% BY 4 PM THIS AFTERNOON ACROSS THESE
WATERS AND PEAK 70-100% A FEW HOURS PRIOR TO DAYBREAK TUESDAY.
GIVEN THESE TRENDS AND THE PATTERN SETUP, A SMALL CRAFT ADVISORY
HAS BEEN ISSUED FOR THE SOUTH SANTEE-EDISTO BEACH NEARSHORE LEG
FROM 4 PM UNTIL 6 AM TUESDAY. THE ADVISORY MAY NEED TO BE
EXPANDED SOUTH INTO THE EDISTO BEACH-SAVANNAH NEARSHORE LEG
LATER TODAY, BUT THE SITUATION LOOKS A BIT TOO MARGINAL TO HOIST
AN ADVISORY AT THIS TIME. ALTHOUGH ADVISORY THRESHOLDS WILL BE
MET OVER BOTH SOUTH CAROLINA OFFSHORE ZONES, SMALL CRAFT
ADVISORIES ARE NOT CURRENTLY BEING ISSUED FOR THESE WATERS.
SEAS WILL AVERAGE 2-4 FT, EXCEPT BUILD TO 4-5 FT OVER THE SOUTH
SANTEE-EDISTO BEACH OFFSHORE LEG AFTER MIDNIGHT.
TUESDAY THROUGH SATURDAY: A WEAK COLD FRONT WILL APPROACH THE
CAROLINA COAST TUESDAY AND STALL THROUGH THE END OF THE WEEK. A
PINCHED PRESSURE GRADIENT FROM OFFSHORE HIGH PRESSURE AND LOW
PRESSURE IN THE MID ATLANTIC WILL RESULT IN GUSTS APPROACHING 25
KNOTS AT TIMES TUESDAY, ESPECIALLY ACROSS THE CHARLESTON COUNTY
NEARSHORE WATERS. A BRIEF SMALL CRAFT ADVISORY COULD BE NEEDED,
MAINLY BETWEEN THE AFTERNOON AND EVENING HOURS. THEREAFTER, THE
PRESSURE GRADIENT WILL RELAX AS HIGH PRESSURE GRADUALLY
REBUILDS OVER LAND. THERE ARE NO ADDITIONAL MARINE CONCERNS
THROUGH THE REMAINDER OF THE PERIOD.
CLIMATE
RECORD HIGH MINIMUM TEMPERATURES:
JUNE 23:
KCHS: 78/2024
KCXM: 82/1998
KSAV: 77/2017
CHS WATCHES/WARNINGS/ADVISORIES
GA...NONE.
SC...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 4 PM THIS AFTERNOON TO 6 AM EDT
TUESDAY FOR AMZ360.
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