671
FXUS64 KMEG 200516
AFDMEG
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEMPHIS TN
1216 AM CDT MON JUL 20 2026
..NEW AVIATION
KEY MESSAGES
ISSUED AT 1214 AM CDT MON JUL 20 2026
- AN EXTREME HEAT WARNING HAS BEEN ISSUED FOR PORTIONS OF
NORTHWEST MISSISSIPPI AND AREAS WEST OF THE MISSISSIPPI RIVER
ALONGSIDE A HEAT ADVISORY ACROSS THE REST OF THE MID-SOUTH FOR
MONDAY AND TUESDAY.
- EXPECT AFTERNOON HEAT INDICES BETWEEN 105 - 115 UNTIL A COLD
FRONT REACHES THE AREA WEDNESDAY, DROPPING HEAT INDICES BELOW
100 FOR THE REMAINDER OF THE WEEK.
- PORTIONS OF WEST TENNESSEE ARE CURRENTLY PLACED IN A MARGINAL
(LEVEL 1 OUT OF 5) RISK FOR SEVERE WEATHER ON TUESDAY. THE
PRIMARY HAZARDS ARE CURRENTLY EXPECTED TO BE LARGE HAIL AND
DAMAGING WINDS.
DISCUSSION
(TONIGHT THROUGH NEXT SUNDAY)
ISSUED AT 1118 PM CDT SUN JUL 19 2026
SCATTERED SHOWERS AND THUNDERSTORMS WILL CONTINUE TO PRODUCE
LOCALLY HEAVY RAINFALL AND FLASH FLOODING THROUGH EARLY MORNING
MONDAY. STORMS ARE FIRING ALONG REMNANT OUTFLOW BOUNDARIES FROM
ANTECEDENT SUNDAY AFTERNOON CONVECTION. THE MAIN FOCUS OF
THUNDERSTORM GENERATION IN THE NEAR TERM IS ACROSS PORTIONS OF
WEST TENNESSEE WHERE A HIGHER COVERAGE OF CONVECTION HAS BEEN
NOTED ALONG A MULTI-BOUNDARY COLLISION. UPPER WINDS PARALLEL TO
THIS COLLISION CORRIDOR, PWATS BETWEEN 2.0" - 2.3+", AND THE
PRESENCE OF MUCAPE ABOVE 1000 J/KG WILL CONTINUE TO PROVIDE
SUPPORT FOR THIS AXIS OF PRECIPITATION TO PRODUCE VERY HEAVY
RAINFALL THROUGH THE NEXT FEW HOURS. SOME HRRR GUIDANCE HAS SHOWN
SOME SUPPORT FOR THIS AREA OF SHOWERS AND STORMS TO LAST UNTIL 2 -
3 A.M. CDT.
MONDAY WILL MARK YET ANOTHER DAY OF RISING TEMPERATURES AS
RIDGING AMPLIFIES FURTHER ACROSS THE CENTRAL AND EASTERN CONUS IN
THE WAKE OF AN UPPER TROUGH. SURFACE TEMPERATURES ARE ANTICIPATED
TO RISE INTO THE MID TO UPPER 90S THROUGHOUT THE AFTERNOON AMIDST
A VERY TROPICAL AIRMASS. THEREFORE, HEAT INDEX VALUES ARE LIKELY
TO EXCEED 105 F ACROSS THE VAST MAJORITY OF THE MID-SOUTH. SOME
AREAS, ESPECIALLY WEST OF THE MISSISSIPPI RIVER, COULD EXPERIENCE
HEAT INDEX VALUES GREATER THAN 110 F. NEWER GUIDANCE THIS EVENING
HAS PLACED THESE 110 F TEMPERATURES MORE NORTH THAN BEFORE,
PROMPTING THE EXPANSION OF THE EXTREME HEAT WARNING FARTHER NORTH
INTO NORTHEASTERN ARKANSAS AND THE MISSOURI BOOTHEEL. SOME
SHOWERS AND STORMS ARE POSSIBLE THROUGH THE AFTERNOON DUE SOME
RESIDUAL TROUGHING FROM TROPICAL DEPRESSION TWO ACROSS
NORTHEASTERN MISSISSIPPI. HOWEVER, THE COVERAGE OF ANY CONVECTION
IS EXPECTED TO BE LOW AND IS NOT EXPECTED TO MEANINGFULLY COOL
AFTERNOON TEMPERATURES.
TUESDAY IS MORE OF THE SAME: ADDITIONAL WARMING UNDER AN
AMPLIFYING RIDGE. HEAT INDEX VALUES WILL CLIMB IN CONCERT WITH
VALUES SOARING WELL ABOVE 105 F AT MOST LOCATIONS IN THE REGION.
NOTABLY, THE EASTERN EXTENT OF 110 F HEAT INDICES HAS SHIFTED
EAST TONIGHT, MEANING THAT CONFIDENCE IS RISING IN AREAS JUST
EAST OF THE MISSISSIPPI RIVER NEEDING AN EXTREME HEAT WARNING
TUESDAY. HOWEVER, FOR NOW WE WILL DEFER TO TOMORROW'S FORECAST IN
LIEU OF REMAINING FORECAST UNCERTAINTIES IN MODEL GUIDANCE.
ON TOP OF THE EXTREME HEAT TUESDAY, ANOTHER WAVE IN THE BROADER
UPPER FLOW WILL EJECT SOUTHWARD INTO THE MID-SOUTH THROUGHOUT THE
DAY. BY LATE AFTERNOON, A ZONE OF UPPER DIFFLUENCE WILL
OVERSPREAD THE OHIO RIVER VALLEY AND MID-SOUTH AHEAD OF A 50 -
70 KNOT MID-LEVEL JET STREAK. HIGH SURFACE THETA E, RESPONSIBLE
FOR THE DANGEROUS HEAT, WILL ALSO YIELD AFTERNOON MLCAPE VALUES
ABOVE 3500 J/KG OVER MUCH OF THE REGION. DEPENDING ON THE AMOUNT
OF HEIGHT FALLS AND/OR UPPER DIVERGENCE, ENOUGH CAPPING MAY ERODE
TO ALLOW FOR THUNDERSTORM DEVELOPMENT INTO THE LATE AFTERNOON AND
EVENING. THIS IS MOST LIKELY TO OCCUR ON A COLD FRONT SITUATED
ACROSS MISSOURI AND SOUTHERN ILLINOIS THAT WILL TRAVEL SOUTHWARD
THROUGH THE DAY. TIMING MAY PRECLUDE A LARGER RISK OF SEVERE
WEATHER AS MOST GUIDANCE PREVENTS THE BOUNDARY FROM MAKING IT
INTO THE REGION UNTIL AFTER SUNSET AND THE FACT THAT OUR AREA
WILL BE UNDER THE SUBSIDENT REGION WITHIN THE RIGHT EXIT REGION
OF THE JET STREAK. NONETHELESS, 30 - 40 KNOTS OF SHEAR WILL BE
PRESENT FOR STORMS TO WORK WITH WELL INTO THE NIGHT WITH ENOUGH
OF A NORTHERLY COMPONENT TO ORGANIZE A WEST-TO-EAST LINE OF
CONVECTION CAPABLE OF DAMAGING WINDS AND LARGE HAIL. THEREFORE,
PORTIONS OF WEST TENNESSEE ARE IN A MARGINAL (LEVEL 1/5) RISK FOR
SEVERE WEATHER WITH THE POTENTIAL FOR EITHER AN EXPANSION OR AN
UPGRADE TO THE SEVERE RISK IN THE NEXT 48 HOURS. FLASH FLOODING
IS ALSO POSSIBLE, BUT STORM MOTIONS ARE ANTICIPATED TO BE TOO
FAST FOR A MORE APPRECIABLE THREAT.
REGARDLESS OF THE MAGNITUDE OF CONVECTION TUESDAY EVENING, THE
FRONT WILL PASS INTO THE REGION BY WEDNESDAY MORNING, MAKING ITS
WAY THROUGH MUCH OF THE AREA THROUGHOUT THE DAY. THE PASSAGE OF
THE FRONT WILL BRING AFTERNOON TEMPERATURES DOWN ENOUGH TO BRING
AFTERNOON HEAT INDICES BELOW 105 F FOR MANY AREAS. THERE IS STILL
SOME UNCERTAINTY REGARDING HOW FAR SOUTH THE FRONT MAKES IT,
WHICH WILL BE DEPENDENT ON THE COVERAGE OF STORMS TUESDAY EVENING
AND WEDNESDAY MORNING. SO, A FEW AREAS ACROSS NORTHERN
MISSISSIPPI COULD STILL SEE HEAT ADVISORY LEVEL HEAT INDEX VALUES
(105 - 109 F) AND MAY NEED ANOTHER HEAT ADVISORY IN THE COMING
FORECASTS.
THE UPPER PATTERN TAKES A NOTABLE NORTHWESTERLY SHIFT AFTER THE
PASSAGE OF THE FRONT AND THE INITIAL UPPER JET STREAK WITH THE
UPPER RIDGE RETROGRADING WEST. COOLER TEMPERATURES WILL PREVAIL
THROUGH THE END OF THE WEEK WITH HIGHS IN THE MID 80S AND LOW 90S
THURSDAY AND WEDNESDAY. UPPER SUBSIDENCE AND SURFACE DRY AIR
ADVECTION SHOULD BE STRONG ENOUGH TO KEEP INSTABILITY AT BAY BOTH
DAYS, KEEPING THE FORECAST MOSTLY DRY APART FROM A FEW AFTERNOON
RENEGADE SHOWERS. MODELS INDICATE THAT THE UPPER TROUGHING LATE
THIS WEEK WILL DEGRADE IN AMPLITUDE INTO NEXT WEEKEND WITH WARMER
TEMPERATURES RETURNING TO THE FORECAST, BUT AT THIS TIME
TEMPERATURES DO NOT APPEAR TO GET AS HOT AS THEY WILL BE EARLY
THIS WEEK.
AVIATION
(06Z TAFS)
ISSUED AT 1214 AM CDT MON JUL 20 2026
VFR CONDITIONS ARE EXPECTED THROUGHOUT THE PERIOD. LINGERING
SHOWERS AND THUNDERSTORMS NEAR MEM AND JBR WILL DISSIPATE WITHIN
THE NEXT FEW HOURS. WINDS WILL REMAIN LIGHT AND VARIABLE (6 KNOTS
OR LESS) WITH A WESTERLY TO SOUTHERLY COMPONENT. MKL HAS A LOW-TO-
MODERATE PROBABILITY OF MVFR FOG OVERNIGHT. DESPITE UPPER-LEVEL
HIGH PRESSURE LIMITING CONVECTION, A SIGNAL FOR POTENTIAL
ACTIVITY REMAINS NEAR TUP TOMORROW EVENING.
FIRE WEATHER
ISSUED AT 1118 PM CDT SUN JUL 19 2026
FIRE WEATHER CONCERNS ARE NOT ANTICIPATED AS AMPLE MOISTURE
REMAINS OVER THE MID-SOUTH AND 20FT WINDS STAY BELOW 10 MPH.
MEG WATCHES/WARNINGS/ADVISORIES
AR...EXTREME HEAT WARNING FROM 10 AM THIS MORNING TO 9 PM CDT TUESDAY
FOR ARZ009-018-026>028-035-036-048-049-058.
MO...EXTREME HEAT WARNING FROM 10 AM THIS MORNING TO 9 PM CDT TUESDAY
FOR MOZ113-115.
MS...EXTREME HEAT WARNING FROM 10 AM THIS MORNING TO 9 PM CDT TUESDAY
FOR MSZ007-010-011-020.
HEAT ADVISORY FROM 10 AM THIS MORNING TO 9 PM CDT TUESDAY FOR
MSZ001>006-008-009-012>017-021>024.
TN...HEAT ADVISORY FROM 10 AM THIS MORNING TO 9 PM CDT TUESDAY FOR
TNZ001>004-019>022-048>055-088>092.
PUBLIC FORECAST...JAB
AVIATION...AC3
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