847
FXUS62 KCAE 092341
AFDCAE
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
741 PM EDT FRI OCT 9 2026
WHAT HAS CHANGED
HURRICANE ISAIAS ABOUT TO MAKE LANDFALL ALONG THE FLORIDA
PANHANDLE THIS EVENING. FLOOD WATCH ISSUED FOR SAME COUNTIES AS
WIND ADVISORY FOR SATURDAY AND SATURDAY NIGHT. AVIATION
DISCUSSION UPDATED FOR 00Z TAFS.
KEY MESSAGES
- 1. AN ACTIVE WEEKEND AHEAD AS HURRICANE ISAIAS MOVES INLAND TO
OUR WEST. CONFIDENCE IN THE EXTENT OF IMPACTS INCREASING WITH
PERIODS OF HEAVY RAIN BRINGING AN ISOLATED FLOODING THREAT.
ISOLATED TORNADOES ARE POSSIBLE ON SATURDAY NIGHT AS WELL.
DISCUSSION
KEY MESSAGE 1: AN ACTIVE WEEKEND AHEAD AS HURRICANE ISAIAS
MOVES INLAND TO OUR WEST. CONFIDENCE IN THE EXTENT OF IMPACTS
INCREASING WITH PERIODS OF HEAVY RAIN BRINGING AN ISOLATED
FLOODING THREAT. ISOLATED TORNADOES ARE POSSIBLE ON SATURDAY
NIGHT AS WELL.
OVERVIEW: MODERATE TO HEAVY RAINFALL IS LIKELY AS HURRICANE
ISAIAS PASSES TO OUR WEST ON SATURDAY AND INTO SATURDAY NIGHT.
OVERALL, THE FORECAST HAS NOT CHANGED SIGNIFICANTLY SINCE
YESTERDAY AFTERNOON WITH THE 00Z AND 12Z SUITE OF GUIDANCE BEING
FAIRLY SIMILAR AND IN LINE WITH FORECAST THINKING. WIDESPREAD
CLOUDS WILL CONTINUE TO THICKEN AND LOWER AS ISAIAS LANDFALLS
AND MOVES INLAND OVERNIGHT. MOISTURE ADVECTION WILL BE
RELATIVELY QUICK THIS EVENING WITH PWS RISING FROM WHERE THEY
ARE CURRENTLY WHICH IS AROUND 0.8" TO WELL OVER 2" BY SATURDAY
MORNING.
RAINFALL IS EXPECTED TO ACCOMPANY THIS SYSTEM & SHOULD BECOME
MORE WIDESPREAD SOMETIME AFTER MIDNIGHT TONIGHT. FORCING THIS
RAINFALL WILL BE A COMBINATION OF STRONG MOISTURE TRANSPORT &
ISENTROPIC ASCENT ATOP AN IN-SITU WEDGE ACROSS THE AREA. IT
DOESN'T HURT THAT SYNOPTIC SCALE LIFT SHOULD BE PRETTY GOOD AS
WELL AS THE RIGHT-ENTRANCE REGION OF AN UPPER LEVEL JET STREAK
PUSHES NORTHWARD INTO THE MID-ATLANTIC. GUIDANCE IS EFFECTIVELY
IN TWO CAMPS: NARROW BANDS OF HEAVY CONVECTIVE PRECIP VS
WIDESPREAD ISENTROPICALLY FORCED PRECIP. AS EXPECTED, AND WHAT
IS LIKELY MORE PHYSICALLY LIKELY, THE HI-RES GUIDANCE FOCUSES
TWO BANDS OF TRAINING CONVECTION. ONE ACROSS CENTRAL GA AND
ANOTHER ALONG A SECONDARY TROUGH AND HEAVY RAINFALL AXIS ALONG
THE COAST WITH RAINFALL TOTALS 3-5", BUT OUTSIDE OF OUR FORECAST
AREA FOR NOW. THE 18Z GUIDANCE IS TRENDING A BIT MORE EASTWARD
WITH THE BAND OF TRAINING CONVECTION INTO THE CSRA AND WESTERN
MIDLANDS WITH POTENTIAL FOR 3-6 INCHES OF RAIN AND POSSIBLE
LOCALLY HIGHER AMOUNTS. THE HRRR, HREF, AND REFS ALL PAINT A
SIMILAR PICTURE WITH THIS BANDING SETUP, LEAVING THE EASTERN
MIDLANDS AS A RELATIVE MINIMUM IN THE REGION. THE GLOBAL AND AI
GUIDANCE DO NOT CAPTURE THIS BANDING, WITH A BROAD BRUSH 2-4"
ACROSS THE REGION BUT IS LIKELY NOT A PHYSICALLY REALISTIC
SOLUTION. THE HI-RES LPMM GENERALLY DOES A NICE JOB PORTRAYING
THE FOOTPRINT WELL FOR HEAVY RAIN EVENTS AS THIS TIME RANGE,
BUT USUALLY STRUGGLES SPATIALLY. SO SHIFTS OF 25-50 MILES WITH
THIS BANDING IS HIGHLY PLAUSIBLE, BRINGING A BOOM OR BUST
POTENTIAL TO MUCH OF THE AREA. TRUSTING THE ENTIRE HI-RES
ENSEMBLE A BIT MORE, AND WITH LREF-HREF-REFS PROBS OF OVER 4"
ARE ABOUT 30% IN THESE AREAS, DECIDED TO GO AHEAD AND ISSUE A
FLOOD WATCH FOR POTENTIAL FLASH FLOODING IN THE CSRA INCLUDING
EDGEFIELD COUNTY WHERE CONFIDENCE IS HIGHEST. CONFIDENCE IS
INCREASING THAT THE PEE DEE WILL LIKELY BE THE DRIEST SPOT,
SANDWICHED BETWEEN AREAS OF STRONG CONVECTION AND LIFTING
DYNAMICS BY THE TIME THE DEEPEST MOISTURE ARRIVES.
THERE ARE OTHER POTENTIAL HAZARDS AT PLAY WITH THIS EVENT.
TORNADOES ARE CERTAINLY POSSIBLE IN THIS EVENT, ESPECIALLY
SATURDAY AFTERNOON AND NIGHT. AS ISAIAS' CIRCULATION LIFTS
NORTHWARD, THE AFORMENTIONED THERMAL GRADIENT IS EXPECTED TO
LIFT NORTHWARD AS WELL. THE TIMING OF THIS SHOULD BE SUCH THAT
IT OCCURS AS THE BEST MOISTURE TRANSPORT APPROACHES BEHIND THE
INITIAL WARM FRONT, WHICH COULD CREATE A SCENARIO ON SATURDAY
NIGHT THAT WE SEE LOW- TOPPED SUPERCELLS DEVELOP IN A HIGHLY
SHEARED ENVIRONMENT. LCLS WILL BE QUITE LOW, AND WE TYPICALLY
DON'T NEED MUCH MORE THAN A SURFACE DEWPOINT OF 70F TO HAVE SOME
TROPICAL TORS DEVELOP. THE RRFS AND HRRR HAVE BOTH SHOWN SIGNS
OF DEVELOPING THE NECESSARY CONVECTION AS WELL AS PUSHING
SUFFICIENT LOW-LEVEL CAPE INTO THE AREA ON SATURDAY NIGHT. SPC
HAS PLACED THE AREA IN A SLIGHT RISK, DRIVEN BY A TORNADO
THREAT. HAVE MULTIPLE WAYS TO RECEIVE WARNINGS ON SATURDAY
NIGHT!
WINDS ARE THE OTHER THREAT BUT LIKELY THE LEAST IMPACTFUL. SOME
GUSTS OVER 40 MPH ARE EXPECTED IN THE WESTERN MIDLANDS AND AS A
RESULT, A WIND ADVISORY HAS BEEN ISSUED TO COVER THIS POTENTIAL
THROUGHOUT SATURDAY. OTHERWISE, IT SHOULD JUST BE BREEZY ACROSS
MUCH OF THE AREA, WITH GUSTS OF 25-35 MPH POSSIBLE ESPECIALLY
SATURDAY MORNING AND EARLY AFTERNOON.
AVIATION /00Z SATURDAY THROUGH WEDNESDAY/
DETERIORATING CONDITIONS TONIGHT INTO SATURDAY.
CEILINGS ARE EXPECTED TO LOWER OVERNIGHT, EVENTUALLY REACHING
IFR CONDITIONS BY ABOUT 12Z AND REMAIN THERE THROUGH THE REST
OF THE TAF PERIOD. THERE IS POTENTIAL FOR CEILINGS TO REACH LIFR
AT TIMES DURING THE DAY SATURDAY AS WELL. RAINFALL SPREADS
ACROSS THE AREA OVERNIGHT FROM SOUTH TO NORTH. VISIBILITIES WITH
THE RAIN ARE GENERALLY FORECAST TO BE IN THE 3-5 SM RANGE WITH
SOME LOWER VIS AT TIMES. NORTHEAST WINDS ARE EXPECTED TO
INCREASE OVERNIGHT INTO SATURDAY MORNING, WITH GUSTS NEARING 30
KTS AT AGS, DNL, AND AIK BEGINNING AROUND 12Z AND LASTING FOR A
FEW HOURS BEFORE GRADUALLY DECREASING. THE STRONGEST WINDS AT
CAE, CUB, AND OGB ARE ANTICIPATED TO BE SLIGHTLY LOWER.
EXTENDED AVIATION OUTLOOK...PERIODS OF RAIN CONTINUES OVERNIGHT
SATURDAY INTO SUNDAY, LEADING TO ONGOING RESTRICTIONS.
CONDITIONS BEGIN IMPROVING LATER ON SUNDAY AND INTO EARLY NEXT
WEEK.
CAE WATCHES/WARNINGS/ADVISORIES
SC...WIND ADVISORY FROM 5 AM TO 11 PM EDT SATURDAY FOR SCZ018-025.
FLOOD WATCH FROM SATURDAY MORNING THROUGH SATURDAY EVENING FOR
SCZ018-025.
LAKE WIND ADVISORY FROM 5 AM TO 11 PM EDT SATURDAY FOR SCZ016-
020>022-026>031-035-037-038-041-115-116-135>137.
GA...WIND ADVISORY FROM 5 AM TO 11 PM EDT SATURDAY FOR GAZ040-
063>065-077.
FLOOD WATCH FROM SATURDAY MORNING THROUGH SATURDAY EVENING FOR
GAZ040-063>065-077.
DISCUSSION...23/42
AVIATION...29
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