780
FXUS64 KJAN 201125 AAA
AFDJAN
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE JACKSON MS
625 AM CDT THU AUG 20 2026
..NEW AVIATION
KEY MESSAGES
- DANGEROUS HEAT STRESS CONDITIONS ARE EXPECTED ACROSS AT LEAST
PORTIONS OF THE FORECAST AREA THROUGH THE END OF THIS WEEK.
- ISOLATED SEVERE STORMS CAPABLE OF DAMAGING WIND GUSTS ARE
POSSIBLE ACROSS PORTIONS OF THE AREA AGAIN TODAY.
DISCUSSION
ISSUED AT 352 AM CDT THU AUG 20 2026
THROUGH TONIGHT: IT WILL BE A LITTLE LESS OPPRESSIVE WITH A GREATER
COVERAGE OF CONVECTION THROUGH THIS EVENING. HOWEVER, HEAT AND
HUMIDITY WILL REMAIN THE MAIN CONCERN IN THE SHORT TERM. IN
ADDITION, THERE WILL ALSO BE THE POTENTIAL FOR ISOLATED STRONG TO
SEVERE STORMS GENERALLY NORTH OF HIGHWAY 84 THIS AFTERNOON INTO THIS
EVENING.
EARLY MORNING SATELLITE IMAGERY/RAP ANALYSIS STILL SHOWED OUR CWA ON
THE EASTERN PERIPHERY OF A WEAKENED 592DAM RIDGE BUT ALSO AT THE
BASE OF A DEEPENING UPPER LEVEL TROUGH THAT WILL CONTINUE TO PROVIDE
NORTHWEST FLOW ALOFT THROUGH TONIGHT AND LEAD TO A GREATER COVERAGE
OF CONVECTION. AT THE SURFACE THERE WAS STILL A NEARLY DIFFUSE
STALLED FRONTAL BOUNDARY THAT WAS NOTED ACROSS OUR NORTHERN MOST
COUNTIES SIMILAR TO WEDNESDAY, CONVECTION IS EXPECTED TO INITIATE
ALONG THIS STALLED BOUNDARY AND SPREAD TO THE SOUTHEAST ACROSS OUR
CWA INTO THIS EVENING. LATEST GUIDANCE SUGGESTS THE ENVIRONMENT WILL
SUPPORT ISOLATED STRONG TO SEVERE STORMS CAPABLE OF DAMAGING WIND
GUSTS. THIS WILL BRING SOME RELIEF TO THE HEAT STRESS TODAY BUT
OTHERWISE, TEMPERATURES IN THE UPPER 90S TO LOWER 100S WILL COMBINE
WITH RELATIVELY HIGH HUMIDITY TO RESULT IN HEAT INDICES BETWEEN 105-
110F AGAIN. THUS, A HEAT ADVISORY REMAINS IN EFFECT FOR THE WHOLE
CWA TODAY. THE CONVECTION WILL TAPER OFF BY MIDNIGHT BUT THE WARM
AND HUMID CONDITIONS WILL CONTINUE THROUGH TONIGHT. /22/
FRIDAY THROUGH NEXT THURSDAY...
DANGEROUS HEAT AND HUMID CONDITIONS WILL CONTINUE TO BE THE PRIMARY
FOCUS FOR OUR AREA OVER THE NEXT SEVERAL DAYS AND INTO THE NEW WORK
WEEK. SEVERAL SITES WILL CONTINUE TO SEE AFTERNOON HIGHS PEAK AROUND
100 DEGREES, WITH PEAK HEAT INDEX READING VALUES AROUND THE 105-110
DEGREE RANGE. A FEW SITES ACROSS PORTIONS OF WEST MS COULD SEE HEAT
INDEX VALUES BRIEFLY REACH 115 DEGREES. AN "ELEVATED" THREAT FOR
DANGEROUS HEAT WILL CONTINUE TO BE ADVERTISED ACROSS OUR ENTIRE
FORECAST AREA FOR FRIDAY. LIKEWISE, AN AREAWIDE HEAT ADVISORY WILL
LIKELY BE NEEDED FOR FRIDAY AS WELL.
SIMILAR TO YESTERDAY, LATE AFTERNOON/EARLY EVENING SHOWERS AND T-
STORMS SHOULD KEEP HEAT INDEX VALUES JUST BELOW EXTREME HEAT WARNING
CRITERIA. WILL REASSESS DURING THE MORNING SHIFT LATER THIS MORNING
TO SEE IF AN UPGRADE TO AN EXTREME HEAT WARNING MAY BE NEEDED. IF AN
HEAT WARNING IS INTRODUCED FOR FRIDAY, ORIGINAL THINKING IS TO HAVE
THE WARNING COVER PORTIONS OF WEST MS, SOUTHWEST MS, AND PORTIONS OF
NORTHEAST LA.
REGARDING THE RAIN CHANCES FOR FRIDAY, GUIDANCE CONTINUES TO SHOW
THE FRONTAL BOUNDARY REMAINING LOCKED IN PLACE OVER THE SOUTHEAST
CONUS. THIS STALLED BOUNDARY COMBINED WITH STEADY MOISTURE CONTENT
(AS SEEN WITH DEWPOINTS REMAINING IN THE LOW TO MID 70S FRIDAY
AFTERNOON), WILL HELP INCREASE THE RISK FOR SOME SCATTERED STRONG TO
MARGINALLY SEVERE T-STORMS ALONG AND SOUTH OF I-20. THE SLIGHTLY
HIGHER STORM COVERAGE (POPS BETWEEN 35-40%) DOES APPEAR TO BE
ACROSS PORTIONS OF SOUTHEAST MS.
GRADUAL EASING IS EXPECTED AS THIS FRONTAL BOUNDARY AND DRIER AIR
EDGE SOUTHWARD INTO THE WEEKEND, BUT AFTERNOON HEAT INDEX VALUES ARE
STILL EXPECTED TO PEAK NEAR OR ABOVE 105 DEGREES INTO EARLY NEXT
WEEK ESPECIALLY IN THE SOUTHWESTERN HALF OF OUR FORECAST AREA. LATE
AFTERNOON/EARLY EVENING RAIN COVERAGE WILL BEGIN TO INCREASE ACROSS
MUCH OF OUR FORECAST BY EARLY NEXT WEEK MONDAY AND CONTINUE THROUGH
THURSDAY. /CR/
AVIATION
(12Z TAFS)
ISSUED AT 624 AM CDT THU AUG 20 2026
ISOLATED TO SCATTERED TSRA ARE PSBL AGAIN THIS AFTN OVER MOST OF
THE TAF SITES WITH THE EXCEPTION OF GLH AND HEZ. ANY TSRA WILL
LIKELY BRING LOWER FLYING CONDITIONS AND GUSTS IN EXCESS OF
30KTS. OTHERWISE, VFR CONDITIONS WILL PREVAIL AREAWIDE THROUGH THE
END OF THE TAF PERIOD. /22/
PRELIMINARY POINT TEMPS/POPS
JACKSON 99 74 99 72 / 20 40 30 10
MERIDIAN 99 73 97 71 / 20 30 30 10
VICKSBURG 99 75 99 73 / 10 40 20 10
HATTIESBURG 99 74 98 72 / 40 30 40 20
NATCHEZ 100 75 100 74 / 10 30 30 10
GREENVILLE 102 75 100 73 / 20 40 10 10
GREENWOOD 100 73 98 70 / 30 30 10 0
JAN WATCHES/WARNINGS/ADVISORIES
MS...HEAT ADVISORY FROM 11 AM THIS MORNING TO 8 PM CDT THIS EVENING
FOR MSZ018-019-025>066-072>074.
LA...HEAT ADVISORY FROM 11 AM THIS MORNING TO 8 PM CDT THIS EVENING
FOR LAZ007>009-015-016-023>026.
AR...HEAT ADVISORY FROM 11 AM THIS MORNING TO 8 PM CDT THIS EVENING
FOR ARZ074-075.
22/CR/22
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