026
FXUS64 KJAN 210251 AAB
AFDJAN
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE JACKSON MS
951 PM CDT SUN SEP 20 2026
..NEW MESOSCALE UPDATE
KEY MESSAGES
- DANGEROUS LEVELS OF HEAT STRESS WILL CONTINUE TO BE A CONCERN
EARLY THIS WEEK.
- THERE IS A MARGINAL RISK FOR A STRONG TO SEVERE STORMS LATE
MONDAY OVER ESPECIALLY NORTHERN PORTIONS OF THE FORECAST AREA.
MESOSCALE UPDATE
ISSUED AT 935 PM CDT SUN SEP 20 2026
LATEST OBSERVATIONS SUPPORT TREND IN MESOSCALE GUIDANCE HEADING
INTO THE OVERNIGHT HOURS. FOLLOWING FROM EARLIER CONVECTION ACROSS
ALABAMA TO OUR EAST THIS AFTERNOON, AN OUTFLOW BOUNDARY MARKS AN
INCREASE IN HUMIDITY ACROSS OUR EASTERN ZONES. ANALYZED PWAT
VALUES ARE GENERALLY ABOVE 1.7 INCHES EAST OF INTERSTATE 55 LATE
THIS EVENING, AND MUCAPE VALUES ASSOCIATED WITH ELEVATED
INSTABILITY ARE IN THE 2000-3000 J/KG RANGE. WITH A WEAKENING RIDGE
OF HIGH PRESSURE DIRECTLY OVER OUR AREA BEING SQUEEZED BY
TROUGHING FROM THE NORTHWEST AND SOUTHEAST, IT WOULD SEEM THAT
SURFACE/LOW-LEVEL CONVERGENCE WILL BE THE PRIMARY INSTIGATOR OF
NEW CONVECTION OVERNIGHT. HRRR AND OTHER HIGH-RES GUIDANCE
DISAGREE WITH COVERAGE AND INITIATION, BUT A ZONE FROM JACKSON, MS
TO COLUMBUS, MS APPEARS TO BE THE MOST FAVORABLE. SATELLITE
IMAGERY SHOWS ACTIVE MID-LEVEL CLOUD DECK IN A SIMILAR ZONE, AND
SOME WEAK SHOWERS ARE NOTED NEAR THE KGWX RADAR IN NORTHEAST
MS/NORTHWEST AL. SEVERE STORMS ARE NOT EXPECTED, BUT WOULD NOT BE
SURPRISED TO GET SOME ELEVATED THUNDERSTORMS WITH HEAVY DOWNPOURS
AND LOUD THUNDER PLUS OR MINUS THE HOURS AROUND MIDNIGHT TONIGHT.
ALSO LOOKED AT GUIDANCE FOR TOMORROW AFTERNOON AND TOMORROW
EVENING, AND UPDATED WITH LATEST POPS VALUES - FILLING IN AND
ACCOUNTING FOR LOW BIASES UNDER A CHANGING REGIME. THE TROUGH
MOVING IN FROM THE NORTHWEST WILL REPLACE THE LINGERING SHORTWAVE
RIDGE OVERHEAD TOMORROW AFTERNOON. WEAKER INHIBITION ACROSS THE
AREA, AND A NEARBY FRONTAL BOUNDARY TO OUR NORTH WILL HELP TO
TRIGGER AFTERNOON CONVECTION. STILL LOW-TO-MODERATE (20-40%) POPS,
BUT ANY LOCATION IN THE AREA AT LEAST HAS A CHANCE FOR SHOWERS OR
THUNDERSTORMS TOMORROW. THE MARGINAL RISK FOR STRONG TO SEVERE
STORMS REMAINS IN PLACE ACROSS THE NORTHERN HALF OF THE AREA, WITH
DAMAGING WIND GUSTS BEING THE MAIN HAZARD. WITH RAIN CHANCES
INCREASING, AND A REMNANT OF DRIER AIR HANGING ON THROUGH THE
DELTA AREAS, THE LOCAL GRAPHIC FOR HEAT RISK TOMORROW WAS LEVELED
AT "LIMITED" (1 OF 4) FOR TOMORROW. MAX HEAT INDEX VALUES SHOULD
TOP OUT NEAR 105 IN THE HOTTEST AREAS. /NF/
DISCUSSION
ISSUED AT 300 PM CDT SUN SEP 20 2026
ABOVE NORMAL UPPER RIDGING CONTINUES TO PROMOTE WELL ABOVE NORMAL
SURFACE HEAT, AND IN SPITE OF THE LOWER DEWPOINTS AND GREATER
MIXING, WE'RE STILL SEEING LIMITED TO ELEVATED HEAT DANGER IN THE
NEAR TERM AHEAD OF AN APPROACHING COLD FRONT. HOWEVER, RELIEF FROM
THE HEAT IS ON THE WAY. THE COLD FRONT IS EXPECTED TO MOVE
THROUGH THE AREA BY TUESDAY NIGHT/WEDNESDAY, AND THIS WILL BRING
TEMPERATURES AND HUMIDITY LEVELS THAT ARE MUCH MORE TYPICAL OF
SEPTEMBER.
ASIDE FROM THE HEAT, WE WILL BE MONITORING FOR THE POTENTIAL OF A
FEW STRONG/SEVERE STORMS AHEAD OF THE COLD FRONT EARLY THIS WEEK.
FOR MONDAY, PER SPC, THERE IS A MARGINAL SEVERE RISK FOR A FEW
PULSE SEVERE STORMS DURING PEAK HEATING OVER NORTHERN PORTIONS OF
THE AREA. FOR TUESDAY, THERE IS CURRENTLY NO OFFICIAL SPC SEVERE
OUTLOOK IN OUR FORECAST AREA, BUT IT WOULDN'T BE A SURPRISE TO SEE
EASTERN PORTIONS OF THE AREA ENTER THE PICTURE FOR A POSSIBLE
MARGINAL RISK AS WE GET CLOSER IN TIME. LOOKING AHEAD FOR THE LATE
WEEK INTO NEXT WEEKEND, AS MENTIONED, DRIER CONDITIONS CAN BE
EXPECTED WITH "LESS HOT" TEMPERATURES. OVERALL, WEATHER IMPACTS
SHOULD MOSTLY BE TIED TO EARLY WEEK HEAT AND CONVECTIVE POTENTIAL.
/EC/
AVIATION
(00Z TAFS)
ISSUED AT 755 PM CDT SUN SEP 20 2026
VFR CONDITIONS ARE EXPECTED TO PREVAIL AT THE TAF SITES THROUGH
THE PERIOD. THERE IS LOW CONFIDENCE FOR SHRA OR TSRA BEFORE 18Z
MONDAY, AND BUT BETTER CHANCES FOR SHOWERS NEAR KHBG, KPIB, AND
KMEI AFTER 18Z. /NF/
PRELIMINARY POINT TEMPS/POPS
JACKSON 74 96 72 96 / 20 30 20 10
MERIDIAN 72 96 71 96 / 30 30 30 20
VICKSBURG 73 97 72 96 / 10 30 20 10
HATTIESBURG 72 96 72 96 / 20 40 30 20
NATCHEZ 73 96 72 97 / 10 30 20 10
GREENVILLE 76 99 72 96 / 10 20 20 10
GREENWOOD 74 99 71 96 / 10 20 20 10
JAN WATCHES/WARNINGS/ADVISORIES
MS...NONE.
LA...NONE.
AR...NONE.
EC/SAS20/NF
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