789
FXUS62 KCAE 271017
AFDCAE
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
617 AM EDT SAT JUN 27 2026
WHAT HAS CHANGED
A LOW END SEVERE THREAT IS POSSIBLE BOTH TODAY AND SUNDAY WITH
SCATTERED CONVECTION. AVIATION DISCUSSION UPDATED FOR 12Z TAFS.
MINIMUM CHANGE TO HEAT OUTLOOK THE COMING WEEK.
KEY MESSAGES
- 1. SCATTERED AFTERNOON SHOWERS AND STORMS EACH DAY THROUGH
MONDAY. ISOLATED SEVERE STORMS POSSIBLE TODAY AND SUNDAY.
- 2. PROLONGED HOT PATTERN EXPECTED WITH DANGEROUS HEAT POSSIBLE
THIS WEEKEND AND A SIGNAL FOR A MORE IMPACTFUL, INTENSE HEAT
EVENT BY THE END OF NEXT WEEK.
DISCUSSION
KEY MESSAGE 1: SCATTERED AFTERNOON SHOWERS AND STORMS EACH DAY
THROUGH MONDAY. ISOLATED SEVERE STORMS POSSIBLE TODAY AND
SUNDAY.
THERE HAS NOT BEEN A SIGNIFICANT CHANGE TO THE OUTLOOK THIS
WEEKEND AS SURFACE DEW POINTS IN THE LOW TO MID 70S, PWAT'S NEAR
2.0", AND SOLID SURFACE HEATING CONTRIBUTE TO ISOLATED TO
SCATTERED CONVECTION EACH AFTERNOON THIS WEEKEND AND POSSIBLY
AGAIN MONDAY. PRIOR TO THE UPPER RIDGE FULLY BUILDING IN NEXT
WEEK, A COUPLE WEAK SHORTWAVES ARE PROGGED TO MOVE NEAR REGION
ON ITS EASTERN PERIPHERY TODAY AND AGAIN ON SUNDAY. THIS SUBTLE
FORCING IS ALL THAT WILL BE NEEDED IN THIS MOISTURE RICH
ENVIRONMENT (MLCAPE BETWEEN 1500-2000 J/KG) TO GET SCATTERED
SHOWERS AND STORMS GOING. ONE CHANGE TODAY AND SUNDAY IS DEEPER
MIXING IS EXPECTED DURING THE AFTERNOON AND INTO THE EVENING,
AIDING IN CREATING INVERTED "V" PROFILES WHICH CONTRIBUTE TO
DCAPE VALUES BETWEEN 700-1000 J/KG. THIS DEEPER MIXING ALSO
CONTRIBUTES TO TEI VALUES BETWEEN 20-30, INDICATING THE
INCREASED RISK FOR DOWNBURSTS. 00Z CAM'S SUPPORT THE POTENTIAL
FOR ISOLATED STRONG TO SEVERE STORMS/CLUSTERS LATE THIS
AFTERNOON INTO THE EVENING AND AGAIN SUNDAY AFTERNOON AS WELL
WITH MULTIPLE INCLUDING THE HRRR, HRW-ARW, HRW-NSSL, AND RRFS
EXPLICITLY DEPICTING CELLS WITH 40-55 MPH WIND GUSTS. DUE TO
THIS FAVORABLE ENVIRONMENT, AND SUFFICIENT FORCING, A MARGINAL
RISK (LEVEL 1 OUT OF 5) IS SEEN FOR MUCH OF THE FA NORTH OF A
LINE FROM ORANGEBURG TO AIKEN TO LINCOLNTON GA TODAY.
THE UPPER RIDGE BEGINS TO SLOWLY BUILD IN A BIT MORE MONDAY,
BUT LINGERING MOISTURE IS EXPECTED TO BRING ANOTHER
AFTERNOON/EVENING WITH SCATTERED SHOWERS AND STORMS. THERE IS
LESS CONFIDENCE IN POTENTIAL FOR ANY ISOLATED STRONG TO SEVERE
STORMS MONDAY, WHICH IS ALSO DISPLAYED IN RECENT AI/ML GUIDANCE
WHERE A WEAKER SIGNAL IS SHOWN THAN THAT FOR THIS WEEKEND.
KEY MESSAGE 2: PROLONGED HOT PATTERN EXPECTED WITH DANGEROUS
HEAT POSSIBLE THIS WEEKEND AND A SIGNAL FOR A MORE IMPACTFUL,
INTENSE HEAT EVENT BY THE END OF NEXT WEEK.
THE MAJOR MESSAGE HEADING INTO THIS WEEKEND AND FOR THE NEXT
7-10 DAYS FOR THAT MATTER WILL BE THE PROLONGED PERIOD WITH
HOT/HUMID TEMPERATURES. OVERALL, THERE HAS BEEN LITTLE CHANGE
ACROSS CLUSTER AND OTHER ENSEMBLE GUIDANCE. THE GENERAL
EVOLUTION OF THE SYNOPTIC PATTERN IS AS FOLLOWS. WEAK TROUGHING
SHOULD PERSIST ACROSS THE EASTERN CONUS TODAY AND SUNDAY, BUT
WILL INCREASINGLY GIVE WAY TO THE AMPLIFYING RIDGE OVER THE
CENTRAL US INTO EARLY NEXT WEEK. THIS PATTERN WILL AID IN
KEEPING DEW POINTS IN THE LOW TO MID 70S AND BRINGING HIGH
TEMPERATURES INTO THE MID TO UPPER 90S. THESE FACTORS WILL
COMBINE TO BRING HEAT INDICES UP TO AROUND 105F TODAY AND
SUNDAY, THOUGH AFTERNOON CONVECTION MENTIONED IN KEY MESSAGE #2,
MAY AID IN BRINGING SOME REPRIEVE. MONDAY AND TUESDAY ACT A BIT
AS TRANSITION DAYS WITH THE A DEEP TROUGH ACROSS THE WESTERN US
AMPLIFYING THE RIDGE TOWARD THE NAEFS 99.5TH PERCENTILE AS IT
NOW CENTERS OVER THE OHIO VALLEY. FOR THE FA, THIS MEANS HOT
TEMPERATURES IN THE MID TO UPPER 90S PERSIST, BUT BUILDING
SURFACE HIGH PRESSURE IN THE NORTHEAST BEGINS TO AID IN BRINGING
SLIGHTLY "DRIER AIR" THAT LIKELY LINGERS INTO THE MID WEEK
PERIOD. DESPITE THIS, HEAT INDICES NEAR TO JUST ABOVE 100F WILL
REMAIN LIKELY DURING THE EARLY WEEK AND INTO THE MID WEEK.
LATE THIS WEEK AND THE HOLIDAY WEEKEND IS WHERE THE UNUSUALLY
CONSISTENT SIGNAL FOR INTENSE HEAT ACROSS ENSEMBLE AND CLUSTER
GUIDANCE PERSISTS. OF THE FOUR LREF CLUSTERS, NEARLY 70% OF
MEMBERS FALL INTO TWO CLUSTERS FOR THE JULY 2ND-3RD PERIOD,
WHICH IS IMPRESSIVE CONSIDERING THIS IS STILL 6-7 DAYS OUT.
THESE CLUSTERS ALSO DO NOT DIFFER SIGNIFICANTLY IN THE STRENGTH
OF THE ROBUST RIDGE (ALL ARE NEAR THE 99TH PERCENTILE), BUT ONLY
HAVE SLIGHT TIMING DIFFERENCES, ALSO SHOWING THE INCREASED
CONFIDENCE. AS THIS IMPRESSIVE RIDGE BEGINS BUILDING INTO THE
MID ATLANTIC AND 850 MB TEMPERATURES LIKELY NEAR OR EXCEED 20C,
TEMPERATURES PUSHING INTO THE UPPER 90S AND NEAR 100F BECOME
INCREASINGLY LIKELY MAINLY FRIDAY AND SATURDAY. THIS IS SHOWN
WITH AROUND 70% OF INDIVIDUAL MEMBERS ACROSS THE LREF CLUSTERS
SHOWING MAX TEMPERATURES THAT REACH 100F. WITH THE FA NOT BEING
DIRECTLY UNDER THE RIDGE, HUMID CONDITIONS ARE LIKELY AS WELL,
BRINGING HEAT INDICES THAT COULD EXCEED 105F. AS MENTIONED IN
PREVIOUS DISCUSSIONS, POSSIBLE AFTERNOON CONVECTION COULD THROW
A BIT OF A WRENCH IN THIS, BUT CONFIDENCE IN THIS CONVECTION
OCCURRING IS NOT TOO HIGH AT THE MOMENT.
OVERALL, PROLONGED HEAT BUILDS INTO THE FA STARTING THIS
WEEKEND, CONTINUING THROUGH THE WEEK BEFORE POSSIBLY AMPLIFYING
A BIT MORE INTO THE HOLIDAY WEEKEND WHERE HEAT PRODUCTS MAY BE
NEEDED. BE SURE TO TAKE HEAT SAFETY PRECAUTIONS AND MONITOR
CHILDREN, THE ELDERLY, AND PETS.
AVIATION /10Z SATURDAY THROUGH WEDNESDAY/
VFR CONDITIONS LIKELY INTO SATURDAY AFTERNOON WITH TYPICAL
SUMMER CONDITIONS BEFORE SCATTERED STORMS DEVELOP.
THE UNSETTLED, SUMMER PATTERN CONTINUES SATURDAY WITH SOME
SHALLOW LOW IMPACT GROUND FOG IN THE MORNING FOLLOWED BY CU AND
SCATTERED STORMS IN THE AFTERNOON; AS OF 11Z, ONLY STILL VFR
VSBY REDUCTIONS FROM MIFG. LIGHT SOUTHWEST WINDS EXPECTED
THROUGHOUT THE DAY OUTSIDE OF ANY STORMS. CONVECTION SHOULD HOLD
OFF UNTIL AFTER 18Z ACROSS THE AREA, WITH THE BEST CHANCE FOR
STRONGER STORMS AT CAE AND CUB. REGARDLESS, CONFIDENCE IS ONLY
HIGH ENOUGH FOR A PROB30 AT ALL SITES WITH THE EXPECTATION OF A
TEMPO LIKELY IN LATER TAFS.
EXTENDED AVIATION OUTLOOK...DIURNAL CONVECTION AND ASSOCIATED
RESTRICTIONS REMAIN POSSIBLE SUNDAY AND INTO THE EARLY WEEK
BEFORE SLIGHTLY DRIER AIR LIMITS RAIN CHANCES LATER IN THE WEEK.
BRIEF MORNING VSBY/CIG RESTRICTIONS ALSO POSSIBLE INTO EARLY
NEXT WEEK.
CAE WATCHES/WARNINGS/ADVISORIES
SC...NONE.
GA...NONE.
DISCUSSION...DH
AVIATION...42
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