819
FXUS62 KCAE 180647
AFDCAE
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
247 AM EDT FRI SEP 18 2026
WHAT HAS CHANGED
POTENTIAL FOR COLD AIR DAMMING TO DEVELOP BY THE MIDDLE OF NEXT
WEEK. AVIATION DISCUSSION UPDATED FOR 06Z TAFS.
KEY MESSAGES
- 1. ABOVE AVERAGE TEMPERATURES AND INCREASED CHANCES FOR
SHOWERS AND STORMS CONTINUE INTO EARLY NEXT WEEK.
- 2. MORE SEASONABLY COOLER AND DRIER AIR RETURNS BY THE MIDDLE
OF NEXT WEEK.
DISCUSSION
KEY MESSAGE 1: ABOVE AVERAGE TEMPERATURES AND INCREASED CHANCES FOR
SHOWERS AND STORMS CONTINUE INTO EARLY NEXT WEEK.
AN UPPER RIDGE REMAINS IN PLACE, CENTERED TO THE WEST NEAR THE
MISSISSIPPI VALLEY. MEANWHILE, AN UPPER LOW IS VISIBLE IN WATER
VAPOR SATELLITE IMAGERY, JUST OFF THE NORTH FLORIDA COAST. THE
RIDGE IS FORECAST TO RETROGRADE WESTWARD, DRIVEN BY THE UPPER
LOW MOVING WESTWARD OVER FLORIDA AND INTO THE GULF. THIS WILL
LEAVE OUR AREA ON THE PERIPHERY OF THE UPPER RIDGE. MOISTURE
EXPECTED TO INCREASE TODAY, BOTH AROUND THE AXIS OF THE RIDGE
FROM THE NORTH AND FROM ONSHORE FLOW WITH THE LOW TO THE SOUTH
OF THE AREA. TEMPERATURES WILL BE WELL ABOVE AVERAGE WHICH IS
EXPECTED TO PERSIST INTO EARLY NEXT WEEK BEFORE THE RIDGE BREAKS
DOWN BUT TODAY IS EXPECTED TO BE THE HOTTEST DAY WITH THE NAEFS
MEAN INDICATING 850MB TEMPS WILL EXCEED THE 99TH PERCENTILE.
WHILE MOST OF THE DAY WILL LIKELY REMAIN DRY FOR MUCH OF THE
AREA, AS A SHORTWAVE PUSHES IN FROM THE NORTH, SCATTERED SHOWERS
AND STORMS ARE LIKELY TO DEVELOP AND BEGIN TO PUSH INTO THE AREA
LATE AFTERNOON AND EVENING WITH THE HIGHEST CHANCE NORTH OF
I-20. MODERATE DESTABILIZATION AND STRONG LOW LEVEL LAPSE RATES
WILL SUPPORT AN ISOLATED DAMAGING WIND GUST THREAT IN THE
STRONGEST STORMS. WHILE SOME HI-RES MODELS CONTINUE TO SUSTAIN
CONVECTION SOUTHWARD INTO THE OVERNIGHT HOURS, THE SEVERE THREAT
WILL DIMINISH. UNSETTLED PATTERN WILL CONTINUE INTO EARLY NEXT
WEEK WITH LREF PROBABILITY OF PWATS GREATER THAN 1.75 INCH
AROUND 70-80%. WHILE WIDESPREAD FORCING WILL LIKELY BE LIMITED,
THIS DEEP LAYER MOISTURE AND A UNSEASONABLY HOT AND HUMID AIR
MASS WILL SUPPORT SCATTERED SHOWERS AND STORMS EACH AFTERNOON
THROUGH TUESDAY.
KEY MESSAGE 2: MORE SEASONABLY COOLER AND DRIER AIR RETURNS BY
THE MIDDLE OF NEXT WEEK.
THERE REMAINS UNCERTAINTY AS TO THE EXACT PATTERN THAT EVOLVES
TOWARDS THE MIDDLE OF NEXT WEEK. SYNOPTICALLY, WITH
STRENGTHENING UPPER LEVEL CONFLUENCE IN THE NORTHEAST AND A
DEVELOPING AND LIKELY SLOW-MOVING UPPER LOW IN THE MID-
ATLANTIC, THIS WOULD SUPPORT COLD AIR DAMMING DEVELOPING BY THE
MIDDLE OF NEXT WEEK. BLENDED GUIDANCE FAVORS NEAR NORMAL
TEMPERATURES FOR HIGHS, ALTHOUGH THE DISTRIBUTION IS SKEWED
TOWARDS LOWER AMOUNTS. FOR NOW, HIGHS HAVE BEEN ADJUSTED A BIT
BELOW THE BLEND BUT WILL NEED TO CONTINUE TO MONITOR TRENDS OVER
THE COMING DAYS.
AVIATION /06Z FRIDAY THROUGH TUESDAY/
VFR CONDITIONS EXPECTED THROUGH THE FORECAST PERIOD
OUTSIDE OF CONVECTION.
THE UPPER RIDGE WILL RETROGRADE WESTWARD TODAY AND WEAK
SHORTWAVE ENERGY ROTATING AROUND THE RIDGE IS EXPECTED TO HELP
INITIATE CONVECTION OVER THE HIGHER TERRAIN AND PIEDMONT REGION
WHICH THEN SHOULD DRIFT SOUTH THROUGH THE FORECAST AREA. WILL
INCLUDE A PROB30 GROUP FOR POSSIBLE CONVECTION DURING THE
21Z-03Z TIME FRAME BUT CONFIDENCE NOT AS HIGH AT OGB SO LEFT OUT
THERE. SOME HIGHER CLOUDS ON SATELLITE THIS MORNING EXPECTED TO
SINK SOUTH OVER THE AREA BUT MAY DISSIPATE LATER IN THE DAY AND
BECOME REPLACED WITH DIURNAL CUMULUS. CALM TO LIGHT WINDS
THROUGH SUNRISE SHOULD PICK UP TO AROUND 5 KNOTS FROM THE WEST
TO NORTHWEST LATE MORNING AND THEN SHIFT TO A MORE SOUTHERLY
DIRECTION THIS AFTERNOON.
EXTENDED AVIATION OUTLOOK...CHANCES FOR SHOWERS AND STORMS
CONTINUE THROUGH THE WEEKEND. MORNING CIG/VSBY RESTRICTIONS ARE
POSSIBLE THIS WEEKEND AS WELL.
CAE WATCHES/WARNINGS/ADVISORIES
SC...NONE.
GA...NONE.
DISCUSSION...96
AVIATION...23
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