655
FXUS62 KCAE 280006
AFDCAE
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
806 PM EDT SAT JUN 27 2026
WHAT HAS CHANGED
REMOVED TODAY VERBIAGE FROM KEY MESSAGE 1. AVIATION DISCUSSION
UPDATED FOR 00Z TAFS.
KEY MESSAGES
- 1. SCATTERED AFTERNOON SHOWERS AND THUNDERSTORMS POSSIBLE ON
SUNDAY AND MONDAY. A FEW STRONG THUNDERSTORMS ARE POSSIBLE ON
SUNDAY.
- 2. DANGEROUS HEAT POSSIBLE AGAIN ON SUNDAY, WITH A SIGNAL FOR
A MORE IMPACTFUL, INTENSE HEAT EVENT BY THE END OF NEXT WEEK.
DISCUSSION
KEY MESSAGE 1: SCATTERED AFTERNOON SHOWERS AND THUNDERSTORMS
POSSIBLE ON SUNDAY AND MONDAY. A FEW STRONG THUNDERSTORMS ARE
POSSIBLE ON SUNDAY.
AS UPPER-LEVEL RIDGING BEGINS TO BUILD INTO THE REGION, ANOTHER
WEAK SHORTWAVE IS EXPECTED TO MOVE THROUGH THE FA ON SUNDAY.
DEW POINTS INTO THE LOWER TO MID 70S, PWATS AROUND 2.0", AND
STRONG SURFACE HEATING WILL PROMOTE ROBUST DESTABILIZATION IN
THE AFTERNOON, WITH SIMILAR CONDITIONS POSSIBLE AGAIN ON
MONDAY. IN THIS MOISTURE RICH ENVIRONMENT WITH MLCAPE VALUES
BETWEEN 1500-2000 J/KG, ONLY SUBTLE FORCING WILL BE NEEDED TO
INITIATE SHOWERS AND THUNDERSTORMS.
A FEW THUNDERSTORMS MAY BECOME STRONG ON SUNDAY AS STEEP LOW-
LEVEL LAPSE RATES AND MODEST LOW-LEVEL SHEAR SUPPORT STORM
CLUSTERING CAPABLE OF PRODUCING DAMAGING WIND GUSTS. DEEPER
BOUNDAY LAYER MIXING IS EXPECTED TOMORROW AFTERNOON, RESULTING
IN INVERTED-V SOUNDINGS AND DCAPE VALUES BETWEEN 700-1000 J/KG,
WHICH WOULD FAVOR STRONG DOWNDRAFT AND DAMAGING WINDS. THE
EXTENT OF SUNDAYS CONVECTIVE THREAT WILL DEPEND IN PART ON HOW
TODAYS CONVECTION EVOLVES, WITH THE HIGHEST RISK OF SEVERE
WEATHER EXPECTED NORTH AND EAST OF I-26. THE LATEST CAMS
SUGGEST A WEAKENING MCS MAY MOVE ACROSS NEIGHBORING FAS SUNDAY
MIDDAY. WHILE THE SYSTEM IS EXPECT TO WEAKEN AS IT APPROACHES,
IT COULD STILL PROVIDE SUFFICIENT FORCING FOR A FEW STRONGER
THUNDERSTORMS, PARTICULARLY IF IT ARRIVES DURING PEAK HEATING.
THIS POTENTIAL IS WHY THE SPC HAS HIGHLIGHTED OUR NORTHERN AND
EASTERN CWA IN A MARGINAL (1/5) SEVERE WEATHER RISK ON SUNDAY.
LINGERING MOISTURE IS EXPECTED TO BRING ANOTHER AFTERNOON/EVENING
WITH SCATTERED SHOWERS AND THUNDERSTORMS ON MONDAY. HOWEVER,
THERE IS LESS CONFIDENCE FOR ANY ISOLATED STRONG TO SEVERE
THUNDERSTORMS.
KEY MESSAGE 2: DANGEROUS HEAT POSSIBLE AGAIN ON SUNDAY, WITH A
SIGNAL FOR A MORE IMPACTFUL, INTENSE HEAT EVENT BY THE END OF
NEXT WEEK.
THE PRIMARY STORY OVER THE NEXT 7-10 DAYS WILL BE A PROLONGED
STRETCH OF HOT AND HUMID CONDITIONS. A STRENGTHENING UPPER-LEVEL
RIDGE WILL BECOME ESTABLISHED OVER THE LOWER MS VALLEY THIS
WEEKEND BEFORE GRADUALLY EXPANDING EASTWARD. BY THE MIDDLE OF
NEXT WEEK, MOST DETERMINISTIC AND ENSEMBLE GUIDANCE PLACES THE
CENTER OF THE CLOSED RIDGE OVER THE EASTERN CONUS, SUPPORTING
AFTERNOON HIGHS IN THE MID TO UPPER 90S WITH DEW POINTS IN THE
LOW TO MID 70S. HEAT INDICES ARE ARE EXPECTED TO RANGE BETWEEN
100-105F TODAY AND TOMORROW, ALTHOUGH SCATTERED AFTERNOON
CONVECTION COULD PROVIDE LOCALIZED RELIEF.
MONDAY AND TUESDAY WILL SERVE AS TRANSITION DAYS AS A DEEP
WESTERN US TROUGH AMPLIFIES THE DOWNSTREAM RIDGE TO NEAR THE
99.5TH PERCENTILE OF THE NAEFS CLIMATOLOGY. TEMPERATURES WILL
REMAIN HOT, GENERALLY IN THE MID TO UPPER 90S, BUT STRENGTHENING
SURFACE HIGH PRESSURE OVER THE NORTHEAST SHOULD ADVECT SLIGHTLY
DRIER AIR MIDWEEK. LOWER DEW POINTS COMBINED WITH DEEPER
AFTERNOON MIXING AND LOW-LEVEL SUBSIDENCE BENEATH THE RIDGE
SHOULD ALLOW HEAT INDICES TO BACK OFF A BIT AND BE CLOSER TO THE
UPPER 90S TO AROUND 100 DEGREES WHILE ALSO SUPPRESSING ANY
CONVECTIVE DEVELOPMENT THROUGH MUCH OF THE WORK WEEK.
BY LATE WEEK, AND INTO THE HOLIDAY WEEKEND, GUIDANCE CONTINUES
TO MAINTAIN A STRONG UPPER RIDGE, WITH 850-MB TEMPERATURES
APPROACHING OR EXCEEDING 20C. THIS PATTERN FAVORS TEMPERATURES
INCREASING AGAIN, WITH HIGHS CLIMBING INTO THE UPPER 90S AND
POTENTIALLY 100 DEGREES, ESPECIALLY ON FRIDAY AND SATURDAY.
HUMIDITY IS ALSO LIKELY TO INCREASE RESULTING IN HEAT INDICES
THAT COULD EXCEED 105 DEGREES AND POTENTIALLY REACH OUR HEAT
ADVISORY CRITERIA. HOWEVER, AFTERNOON CONVECTION COULD LOCALLY
TEMPER MAX VALUES, BUT CONFIDENCE REMAINS TOO LOW IN COVERAGE TO
SIGNIFICANTLY ALTER THE HEAT FORECAST. BE SURE TO TAKE HEAT
SAFETY PRECAUTIONS AND MONITOR CHILDREN, THE ELDERLY, AND PETS.
ONE LAST THING TO NOTE, AS OF THIS MORNING, NHC PUT OUT A 20%
CHANCE FOR CYCLONE FORMATION OVER THE NEXT 7 DAYS JUST OFF THE
SC COAST. CONFIDENCE REMAINS LOW, AS ENSEMBLE GUIDANCE CONTINUES
TO SHOW CONSIDERABLE SPREAD ON DEVELOPMENT AND TRACK. HOWEVER,
ANY SYSTEM COULD ALTER THE EXPECTED HEAT PATTERN HEADING INTO
THE INDEPENDENCE DAY HOLIDAY, MAKING THIS FEATURE WORTH
MONITORING OVER THE COMING DAYS.
AVIATION /00Z SUNDAY THROUGH THURSDAY/
VFR CONDITIONS LIKELY OUTSIDE OF AFTERNOON CONVECTION SUNDAY.
SHOWERS CONTINUE TO DIMINISH THIS EVENING WITH LOW CHANCES OF
ANY IMPACTS TO THE TERMINALS AFTER 00Z. A 20 KT LLJ TONIGHT WILL
KEEP THE LOW LEVELS RELATIVELY MIXED WITH VARIABLE WINDS UP TO 5
KTS. CONVECTIVE DEBRIS CLOUD SHOULD ALSO HELP TO LIMIT THE
THREAT OF FOG. SIMILAR TO THE PREVIOUS NIGHT WE EXPECT
CONDITIONS TO REMAIN GENERALLY VFR WITH A CHANCE OF BRIEF
RESTRICTIONS AT OGB OR AGS.
SUNDAY MORNING INTO MID-DAY, OUTFLOW FROM OVERNIGHT CONVECTION
IN KY/TN IS EXPECTED TO PUSH INTO THE CAROLINAS. MODELS SHOW ANY
REMAINING SHOWERS OR THUNDERSTORMS DECAYING THROUGH THE MORNING
AND ARE UNLIKELY TO CAUSE ANY IMPACT TO THE TERMINALS PRIOR TO
18Z. HOWEVER THERE IS A SMALL CHANCE OF SHOWERS BETWEEN 12Z AND
18Z. AFTER 18Z, NEW THUNDERSTORMS SHOULD DEVELOP ALONG THE OLD
OUTFLOW BOUNDARY AND WILL BRING A THREAT OF GUSTY WINDS AND
HEAVY RAIN. THEREFORE WE HAVE ADDED A PROB30 GROUP FOR SUNDAY
AFTERNOON TO INCLUDE THUNDERSTORMS IN THE FORECAST. WEST WINDS
ARE EXPECTED SUNDAY AFTER 15Z WITH GUSTS TO 20 KTS.
EXTENDED AVIATION OUTLOOK...AFTERNOON CONVECTION WILL DEVELOP
AGAIN MONDAY BUT IS LESS LIKELY FOR THE REMAINDER OF THE WEEK
AS RIDGING BUILDS OVERHEAD. BRIEF EARLY MORNING RESTRICTIONS
ALSO POSSIBLE EARLY NEXT WEEK.
CAE WATCHES/WARNINGS/ADVISORIES
SC...NONE.
GA...NONE.
DISCUSSION...7
AVIATION...CJR
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