273
FXUS64 KMEG 191713
AFDMEG
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEMPHIS TN
1213 PM CDT WED AUG 19 2026
..NEW DISCUSSION, AVIATION, FIRE WEATHER
KEY MESSAGES
ISSUED AT 12013 PM CDT WED AUG 19 2026
- AN EXTREME HEAT WARNING AND HEAT ADVISORY REMAIN IN EFFECT
THROUGH 8 PM TONIGHT, WITH HEAT INDEX VALUES EXPECTED TO PEAK
BETWEEN 105°F AND 112°F.
- A MARGINAL TO SLIGHT RISK FOR STRONG-TO-SEVERE THUNDERSTORM
THREAT EXISTS TONIGHT, PRIMARILY FOR DAMAGING WINDS AND A
TORNADO OR TWO. ENSURE YOUR WEATHER ALERT NOTIFICATIONS ARE
ENABLED THROUGH THE OVERNIGHT PERIOD.
- A TRANSITION TO A ZONAL/NORTHWEST FLOW REGIME LATE THIS WEEK
WILL BRING DRIER AIR AND COOLER TEMPERATURES FOR THE WEEKEND,
PROVIDING RELIEF FROM THE OPPRESSIVE HEAT.
DISCUSSION
(THIS EVENING THROUGH NEXT TUESDAY)
ISSUED AT 1213 PM CDT WED AUG 19 2026
A LARGE CLUSTER OF SHOWERS AND THUNDERSTORMS IS ONGOING ACROSS
SOUTHERN KENTUCKY AS OF 11 AM WITH A FEW SHOWERS AND STORMS
DIPPING INTO WEST TENNESSEE. THIS CLUSTER WILL CONTINUE ITS E/SE
PROPAGATION THROUGH THE EARLY AFTERNOON AHEAD OF ANOTHER ROUND OF
CONVECTION THIS EVENING. THIS CLUSTER HAS PROHIBITED A WARM FRONT
FROM SURGING TOO FAR NORTH WHICH HAS ALLOWED TEMPERATURES TO NOT
WARM AS RAPIDLY AS PREVIOUS DAYS WITH TEMPERATURES GENERALLY IN
THE 80S AND APPROACHING 90 DEGREES. AREAS BEING AFFECTED BY
CONVECTION ARE STILL MUCH COOLER WITH READINGS IN THE 70S. ONCE
CONVECTION ENDS AND THE WARM FRONT CLEARS THE AREA, EXPECT AN
INFLUX OF MOISTURE AND HEAT INDEX VALUES TO RISE ABOVE 105F, AND
110F IN SOME PLACES. THE EXTREME HEAT WARNING AND HEAT ADVISORY
WILL REMAIN IN EFFECT UNTIL 8 PM.
A SHORTWAVE CURRENTLY OVER NORTHEAST KANSAS AND NORTHWEST
MISSOURI WILL SLOWLY MOVE TOWARDS THE MID-SOUTH AND THREATEN
STRONG TO SEVERE THUNDERSTORMS THIS EVENING INTO THE OVERNIGHT
HOURS. DESPITE THIS THREAT BEING IN THE SHORT TERM, DETAILS ARE
STILL NOT CONCRETE. EACH SUBSEQUENT CAM RUN DELAYS THE ARRIVAL OF
THE SHORTWAVE INTO THE HOURS AFTER SUNSET WHICH DECREASES SURFACE
BASED INSTABILITY. HRRR SOUNDINGS INDICATE THE DEVELOPMENT OF A
STOUT CAP AROUND 850MB, WHICH WOULD PROHIBIT INTENSE SURFACE
BASED CONVECTION. MOST NOCTURNAL EVENTS THIS SUMMER HAVE BEEN A
BUST, DUE TO THE NOCTURNAL EML, BUT THIS EVENT IS A BIT DIFFERENT
IN THAT SHEAR WILL ACTUALLY BE PRESENT. THE LLJ WILL RAMP UP AND
BRING A 60 KT MAXIMA ACROSS SOUTHERN KENTUCKY. THE HRRR AND NAM
SUGGESTS THIS MAXIMUM DIPPING INTO OUR NORTHERN ZONES, WHICH
COULD EASILY THREATEN DAMAGING WINDS, DESPITE THE CAP. DUE TO THE
INTENSITY OF THE LLJ, THIS ALSO INCREASES HELICITY AT OR ABOVE
200 M2/S2. THE CAP DOES BRING LCL VALUES A BIT HIGHER THAN
TYPICALLY DESIRED FOR TORNADOGENESIS, BUT IS VERY DEPENDENT ON
WHERE THE LLJ SETS UP. IF THE LLJ DOES SWING INTO THE NORTHERN
ZONES, DAMAGING WINDS AND A TORNADO OR TWO ARE THE PRIMARY
CONCERNS. RESIDENTS ARE STRONGLY URGED TO ENSURE THEIR PREFERRED
WEATHER ALERT METHOD IS ACTIVE AND AUDIBLE OVERNIGHT, GIVEN THE
PRIMARY THREAT OCCURRING DURING SLEEPING HOURS. RAIN RATES WILL
BE INTENSE DUE TO GREATER THAN 2" PW VALUES, BUT THE
PROGRESSIVENESS OF THIS SYSTEM (AND DAYS OF CONSECUTIVE DRYNESS)
SHOULD ALLEVIATE MAJOR FLOODING CONCERNS.
THURSDAY DURING THE DAYTIME HOURS HAS TRENDED DRIER ON THE 12Z
SUITE, BUT THERE IS LIKELY TO BE REMNANT OUTFLOW BOUNDARIES FROM
THE OVERNIGHT STORMS THAT COULD RESULT IN DIURNALLY DRIVEN
THUNDERSTORMS. WET MICROBURSTS WOULD BE THE PRIMARY CONCERN GIVEN
THE ENVIRONMENTAL PARAMETERS, WITH A MARGINAL RISK (LEVEL 1/5)
FOR DAMAGING WINDS GENERALLY ALONG AND SOUTH OF I-40. OUR
SOUTHERN ZONES HAVE ONE MORE THREATENING DAY FOR HEAT, WHICH
COULD BE COOLER THAN GUIDANCE SUGGESTS IF CONVECTION DOES
DEVELOP, AND ANOTHER HEAT ADVISORY WILL GO INTO EFFECT AT 11 AM
THURSDAY FOR HEAT INDEX VALUES UP TO 108F.
AFTER THURSDAY, DRIER AIR WILL FILTER INTO THE REGION BEHIND A
WEAK COLD FRONT AND COULD BE OUR FIRST DAY WITHOUT HEAT HEADLINES
AS HEAT INDEX VALUES ARE EXPECTED TO FALL BELOW 105F. THE WEEKEND
IS ALSO TRENDING COOLER AND DRIER UNDER ZONAL/NORTHWEST FLOW
ALOFT. THERE IS A CHANCE FOR SHOWERS AND THUNDERSTORMS ON
SATURDAY AS A DEPARTING LOW OVER THE GREAT LAKES REGION STRETCHES
A BOUNDARY ACROSS MUCH OF THE SOUTHEAST, BUT THE COLUMN SHOULD BE
DRY ENOUGH TO PROHIBIT COVERAGE AND ACCUMULATION. LONG RANGE
GUIDANCE OFFERS TWO PRIMARY SCENARIOS FOR NEXT WEEK: EITHER
PLACEMENT ON THE EASTERN PERIPHERY OF THE RIDGE (PROMOTING
NORTHWEST FLOW, COOLER TEMPERATURES, AND INCREASED RAIN CHANCES)
OR DIRECT POSITIONING UNDER THE RIDGE, WHICH WOULD RENEW HOT AND
HUMID CONDITIONS. WE WILL CONTINUE TO MONITOR ENSEMBLE TRENDS.
DNM
AVIATION
(18Z TAFS)
ISSUED AT 1213 PM CDT WED AUG 19 2026
OUTFLOW FROM PREVIOUS CONVECTION ACROSS NORTHEAST ARKANSAS AND
THE MISSOURI BOOTHEEL HAS STALLED ALONG THE I-40 CORRIDOR
RESULTING IN VARIABLE WIND AT MEM AND NORTHERLY FLOW AT JBR AND
MKL. THIS FEATURE MAY ACT AS A FOCUS FOR ADDITIONAL DEVELOPMENT
AS TEMPERATURES WARM THIS AFTERNOON, BUT CONFIDENCE IS NOT HIGH
ENOUGH ENOUGH TO INCLUDE ANY MENTION IN THE TAF AT THIS TIME.
CONFIDENCE IS HIGHER IN A ROUND OF STORMS OVERNIGHT AS A LLJ
DEVELOPS OVER THE REGION. THE PRESENCE OF CONVECTION WILL NEGATE
THE NEED FOR LLWS IN THE TAF. VFR CONDITIONS WILL PREVAIL TOMORROW
WITH SOUTH TO SOUTHWEST WINDS GENERALLY 3-6 KTS.
FIRE WEATHER
ISSUED AT 1213 PM CDT WED AUG 19 2026
AN OVERALL LOW FIRE WEATHER RISK WILL HOLD OVER THE NEXT THREE
DAYS. WHILE TEMPERATURES REMAIN HOT, LIGHT WINDS AND ADEQUATE
MOISTURE LEVELS WILL KEEP CRITICAL FIRE WEATHER CONDITIONS WELL
AT BAY. THERE IS A CHANCE FOR FOG ACROSS THE NORTHERN ZONES
TONIGHT AFTER WETTING RAINFALL, BUT ELSEWHERE FOG POTENTIAL
REMAINS LOW.
MEG WATCHES/WARNINGS/ADVISORIES
AR...HEAT ADVISORY UNTIL 8 PM CDT THIS EVENING FOR ARZ009-018.
EXTREME HEAT WARNING UNTIL 8 PM CDT THIS EVENING FOR ARZ026>028-
035-036-048-049-058.
HEAT ADVISORY FROM 11 AM TO 8 PM CDT THURSDAY FOR ARZ048-049-058.
MO...HEAT ADVISORY UNTIL 8 PM CDT THIS EVENING FOR MOZ113-115.
MS...HEAT ADVISORY UNTIL 8 PM CDT THIS EVENING FOR MSZ002>005-009-
013>017-021>024.
EXTREME HEAT WARNING UNTIL 8 PM CDT THIS EVENING FOR MSZ001-007-
008-010>012-020.
HEAT ADVISORY FROM 11 AM TO 8 PM CDT THURSDAY FOR MSZ007-008-
010>017-020>024.
TN...HEAT ADVISORY UNTIL 8 PM CDT THIS EVENING FOR TNZ019-048-050>053-
089>091.
EXTREME HEAT WARNING UNTIL 8 PM CDT THIS EVENING FOR TNZ049-088.
PUBLIC FORECAST...DNM
AVIATION...JDS
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