702
FXUS62 KILM 120634
AFDILM
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON NC
234 AM EDT SAT SEP 12 2026
WHAT HAS CHANGED
UPDATED TODAY'S FORECAST BASED ON THE LATEST GUIDANCE FOR TIMING
OF SHOWERS AND STORMS. MODELS CONTINUE TO BE CONSISTENT ON THE
STRENGTH AND TIMING OF A COLD FRONT ON MONDAY. THE ONLY CHANGE
TO THE FORECAST DURING THIS UPDATE WAS TO INCREASE WIND SPEEDS
BEHIND THE COLD FRONT ON MONDAY EVENING. WIND GUSTS HAVE ALSO
BEEN INCREASED OVER THE MARINE FORECAST ZONES WITH WARM SSTS.
DRY HIGH PRESSURE WILL FOLLOW, SO FORECAST CHANGES WERE MINIMAL
THROUGH NEXT WEEK.
KEY MESSAGES
1) DEEP GULF MOISTURE AND A BREAK IN THE RIDGE ALOFT WILL
MAINTAIN GOOD CHANCES FOR SHOWERS AND THUNDERSTORMS THROUGH
SUNDAY.
2) WELL-ABOVE NORMAL TEMPERATURES AND HIGH HUMIDITY WILL
MAINTAIN DAYTIME HEAT INDICES AT OR ABOVE 100 DEGREES THROUGH
MONDAY.
3) A MODIFIED CANADIAN AIRMASS SHOULD BRING NEAR-NORMAL
TEMPERATURES BEGINNING TUESDAY.
DISCUSSION
KEY MESSAGE 1... DEEP GULF MOISTURE AND A BREAK IN THE RIDGE
ALOFT WILL MAINTAIN GOOD CHANCES FOR SHOWERS AND THUNDERSTORMS
THROUGH SUNDAY.
DEEP GULF MOISTURE IN PLACE OVER THE CAROLINAS AND ABOVE-NORMAL
TEMPERATURES WILL PRODUCE WIDESPREAD SHOWERS AND THUNDERSTORMS
THIS AFTERNOON. HIGH RESOLUTION MODELS HAVE MAINTAINED POOR
CONSISTENCY EACH HOUR. SURFACE CONVERGENCE ALONG THE SEA BREEZE
IS LIKELY TO BE THE MAIN INITIATOR OF CONVECTION AFTER NOON. A
FEW ISOLATED SHOWERS ARE POSSIBLE IN COASTAL SOUTHEAST NC THIS
MORNING DUE TO ONSHORE FLOW. WEAK SHORTWAVE ENERGY LIFTING
NORTHWARD THROUGH THE CAROLINAS SUGGESTS THAT SOME DEVELOPMENT
IS POSSIBLE DURING THE AFTERNOON FOR INLAND AREAS IN ADDITIONAL
TO SURFACE CONVERGENCE ALONG THE SEA BREEZE. THIS LIFT IS WEAK
AND WOULD FAVOR THE NC/SC BORDER AND POINTS NORTHWARD INTO THE
SANDHILLS.
WEAK SHEAR SHOULD KEEP THE POTENTIAL FOR SEVERE WEATHER LOW.
SOME HEAVY RAIN IS POSSIBLE GIVEN THE NEAR RECORD PW AND
SLOW STORM MOTIONS.
DRIER AIR MOVES INTO THE MOUNTAINS AND WESTERN PIEDMONT ON
SUNDAY, BUT THE MOISTURE-LADEN ATMOSPHERE WILL LARGELY REMAIN IN
TACT NEAR THE COAST. THE UPPER TROUGH PRODUCING THE BREAK IN
THE RIDGE SHOULD SLIDE EASTWARD ACROSS THE CAROLINAS, PERHAPS
ENHANCING BULK SHEAR TO AROUND 20 KNOTS. MULTICELLS SHOULD
BECOME POSSIBLE, PERHAPS BRINGING BETTER POTENTIAL FOR GUSTY
WINDS. THE UPPER TROUGH SHOULD SHIFT OFFSHORE SUNDAY NIGHT AHEAD
OF RISING MID AND UPPER LEVEL HEIGHTS SPREADING EASTWARD FROM
THE MID SOUTH.
KEY MESSAGE 2... WELL-ABOVE NORMAL TEMPERATURES AND HIGH
HUMIDITY WILL MAINTAIN DAYTIME HEAT INDICES AT OR ABOVE 100
DEGREES THROUGH MONDAY.
ABOVE-NORMAL TEMPERATURES CONTINUE TO SIT NEAR THE 90TH
PERCENTILE FOR MID SEPTEMBER. DEEP MOISTURE SHOULD PRODUCE
WIDESPREAD CLOUDINESS IN ADDITION TO CONVECTION THIS WEEKEND.
THESE FACTORS WILL KEEP HEAT INDICES BELOW THE 105 DEGREE
THRESHOLD FOR HEAT ADVISORIES.
ENSEMBLE SPREAD FOR 850 TEMPERATURES REMAINS LOW THROUGH MONDAY,
THE LATEST FORECAST KEEPS FORECAST HIGHS IN THE UPPER 80S TO
AROUND 90 THROUGH MONDAY. WITH DEWPOINTS WELL INTO THE 70S, HEAT
INDICES WILL REMAIN IN THE 100-103 RANGE THROUGH MONDAY. MONDAY
IS EXPECTED TO BE THE WARMEST OF THESE DAYS WITH DECREASED
CLOUDINESS.
NWS ILM HAS NEVER ISSUED A HEAT ADVISORY LATER THAN SEPTEMBER 5
SINCE THE INTRODUCTION OF VTEC PRODUCT CODES TWENTY YEARS AGO.
(AND THAT LATEST ADVISORY WAS EARLIER THIS MONTH)
KEY MESSAGE 3...A MODIFIED CANADIAN AIRMASS SHOULD BRING NEAR-NORMAL
TEMPERATURES BEGINNING TUESDAY.
MODELS HAVE ALL COME INTO LINE OVER THE PAST 24 HOURS SHOWING
THE STRONGEST CANADIAN HIGH WE'VE SEEN SINCE LAST SPRING MOVING
ACROSS NEW ENGLAND TUESDAY INTO WEDNESDAY. THIS SHOULD PUSH A
COLD FRONT SOUTHWARD ACROSS THE EASTERN CAROLINAS MONDAY NIGHT,
ALLOWING A MODIFIED CANADIAN AIRMASS TO SPREAD ACROSS THE AREA
TUESDAY INTO WEDNESDAY. THIS WON'T BE CRISP, DRY CANADIAN AIR BY
ANY MEANS GIVEN ITS LONG PASSAGE ACROSS WATER TEMPS IN THE 70S
AND 80S, BUT IT SHOULD BRING COOLER AIR ACROSS THE AREA KNOCKING
TEMPERATURES BACK DOWN CLOSER TO NORMAL FOR MID SEPTEMBER.
FORECAST LOWS IN PARTICULAR LOOK REFRESHING WITH 60S EXPECTED
FOR ALL BUT EAST-FACING BEACHES TUESDAY NIGHT AND WEDNESDAY
NIGHT. SOME INLAND LOCATIONS COULD CONCEIVABLY DIP TO 60
DEGREES.
AVIATION /06Z SATURDAY THROUGH WEDNESDAY/
REST OF TONIGHT... MIXING SHOULD MAINTAIN VFR FOR COASTAL
TERMINALS, BUT CAN'T RULE OUT SOME BRIEF MVFR CIGS. LIGHT
BOUNDARY LAYER WINDS, WET SOILS, AND ENHANCED LOW LEVEL MOISTURE
SHOULD PRODUCE IFR ACROSS A LARGE PORTION OF INLAND TERMINALS.
EXPECT SOME CIGS TO REACH LIFR BY SUNRISE. LIGHT WIND SHOULD
MIX-OUT RESTRICTIONS A COUPLE OF HOURS AFTER SUNRISE.
SATURDAY... ISOLATED SHOWERS NEAR THE NC COAST MAY PRODUCT
BRIEF RESTRICTIONS AT ILM THIS MORNING (AROUND SUNRISE). AS THE
SEA BREEZE DEEPENS DURING THE EARLY AFTERNOON, CONVECTION SHOULD
MATURE NEAR THE COAST AND GRADUALLY PUSH INLAND THROUGH THE
AFTERNOON. ADDITIONAL DEVELOPMENT IS POSSIBLE INLAND DURING THE
EARLY AFTERNOON. MOST AREAS ARE EXPECTED TO SEE IMPACTS FROM
THUNDERSTORMS BY THE END OF THE DAY AS SHOWERS BECOME
WIDESPREAD.
EXTENDED OUTLOOK... SCATTERED SHOWERS AND THUNDERSTORMS
BRINGING BRIEF MVFR/IFR CONDITIONS ARE EXPECTED TO CONTINUE
INTO SATURDAY EVENING. SOME SHOWERS ARE POSSIBLE ON SUNDAY, BUT
COVERAGE SHOULD BE LESS THAN PREVIOUS DAYS. THERE IS ALSO A LOW
POTENTIAL FOR LATE NIGHT/EARLY MORNING STRATUS OR GROUND FOG
AFFECTING KLBT AND KFLO LATE SATURDAY NIGHT AND AGAIN LATE
SUNDAY NIGHT. VFR CONDITIONS SHOULD PREVAIL MONDAY THROUGH
WEDNESDAY AS A MORE STABLE AND DRIER CANADIAN AIRMASS BUILDS IN
FROM THE NORTHEAST.
MARINE
SOUTHERLY FLOW WILL CONTINUE TO SUPPLY A WARM AND HUMID AIR
MASS THROUGH THE WEEKEND. THIS MOISTURE-LADEN AIR MASS WILL
BRING MULTIPLE ROUNDS OF SHOWERS AND THUNDERSTORMS BOTH SATURDAY
AND SUNDAY NIGHT. SOUTHERLY WINDS AROUND 10-15 KNOTS. THE SEA
BREEZE WILL PRODUCE LOCALIZED ENHANCEMENT OF GUSTS TO 20 KNOTS
EACH AFTERNOON.
DRIER WEATHER SHOULD DEVELOP ON MONDAY EVENING AS HIGH PRESSURE
STRENGTHENS ALOFT OVER THE CAROLINAS. THE STRONGEST CANADIAN
HIGH WE'VE SEEN SINCE LAST SPRING SHOULD MOVE ACROSS NEW ENGLAND
TUESDAY AND WEDNESDAY, PUSHING A COLD FRONT SOUTHWARD ACROSS THE
CAROLINA COASTAL WATERS MONDAY NIGHT. NORTHEAST WINDS BEHIND THE
FRONT SHOULD INCREASE TO A SOLID 20 KNOTS OFFSHORE AND 15-20
KNOTS NEARSHORE TUESDAY INTO TUESDAY NIGHT. SEAS WITHIN 20
MILES OF SHORE COULD BUILD TO 4-6 FEET WITH DOMINANT WAVE
PERIODS NEAR 6 SECONDS.
ILM WATCHES/WARNINGS/ADVISORIES
NC...COASTAL FLOOD ADVISORY FROM 10 AM THIS MORNING TO 1 PM EDT
THIS AFTERNOON FOR NCZ107.
SC...NONE.
MARINE...NONE.
WHAT HAS CHANGED...ILM
KEY MESSAGES...TRA/21
DISCUSSION...TRA/21
AVIATION...21
MARINE...TRA/21
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