784
FXUS64 KMRX 211738
AFDMRX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MORRISTOWN TN
138 PM EDT SAT MAR 21 2026
..NEW AVIATION
KEY MESSAGES
UPDATED AT 131 PM EDT SAT MAR 21 2026
- SCATTERED SHOWERS AND STORMS ARE POSSIBLE LATE THIS AFTERNOON
AND EVENING. THE MAIN THREAT WITH THESE STORMS WILL BE HAIL.
- WARM AND BREEZY ON SUNDAY WITH A LOW CHANCE OF RAIN RETURNING
SUNDAY NIGHT/MONDAY MORNING.
- DRY AND SEASONALLY COOLER CONDITIONS ARE EXPECTED MONDAY UNTIL A
WARMING TREND AND RETURNING RAIN CHANCES LATE IN THE WEEK.
UPDATE
ISSUED AT 1103 AM EDT SAT MAR 21 2026
DUE TO AREA PRESCRIBE BURNS ACROSS THE MISSISSIPPI AND TENNESSEE
VALLEYS AND SOUTHERN APPALACHIANS, A GOOD DEAL OF SMOKE REMAINS
TODAY. HRRR SMOKE PRODUCT SHOWS INCREASING POTENTIAL OF SMOKE
LATER TODAY SO HAVE INCLUDED SMOKE/HAZE INTO THE FORECAST THROUGH
THIS EVENING. ONE OF THE MAIN PROBLEMS WILL BE POOR AIR QUALITY.
HREF AND LATEST DETERMINISTIC MODELS CONTINUE TO SHOW A WEAK WAVE
WITHIN NORTHWEST FLOW ALOFT MOVING ACROSS THE REGION LATE THIS
AFTERNOON AND EVENING. BOUNDARY LAYER REMAINS FAIRLY DRY WITH
DEWPOINTS ONLY IN THE 40S/50S. ENOUGH FORCING AND MLCAPE OF
500-1000 J/KG TO PRODUCE WIDELY SCATTERED TO SCATTERED CONVECTION.
MODEL SOUNDING FORECAST SHOWS DECENT CAPE WITHIN THE HAIL GROWTH
REGION ALONG WITH LOW WBZ HEIGHTS. SHEAR IS QUITE MARGINAL SO
LIMITED STORM SCALE ORGANIZATION WITH MULTI-CELL DEVELOPMENT
ANTICIPATED. MAIN CONCERNS WITH THE LATE DAY CONVECTION WILL BE
MARGINAL SEVERE HAIL UP TO QUARTER SIZE AND GUSTY WINDS UP TO 45
MPH.
OVERALL, LIMITED CHANGES TO ONGOING FORECAST.
DISCUSSION
ISSUED AT 241 AM EDT SAT MAR 21 2026
A SURFACE FRONT WILL BE PUSHING SOUTHWARD ACROSS THE OH VALLEY
TODAY, WHILE A WEAK SHORTWAVE TROUGH WILL APPROACH IN THE NW FLOW
ALOFT. THE FRONT IS EXPECTED TO BE POSITIONED NEAR THE TN/KY
BORDER BY THE AFTERNOON WHEN THE TROUGH CROSSES THE MS RIVER.
CAMS ARE COMING INTO BETTER AGREEMENT ON THE DEVELOPMENT OF
CONVECTION SOUTH OF THE FRONT IN THE CUMBERLAND PLATEAU AREA,
MAINLY AROUND 4-6 PM. THE CONVECTION TRACKS SE INTO THE CENTRAL TN
VALLEY THROUGH THE EVENING. GIVEN THE MIDLEVEL LAPSE RATES OF
AROUND 7-8 C/KM, LOW WBZ HEIGHT BELOW 10K FT, AND MLCAPE AROUND
1000-1200 J/KG, HAIL APPEARS TO BE THE MAIN THREAT FROM STORMS.
WINDS ALOFT ARE NOT PARTICULARLY STRONG (20-30 KT UP TO 500 MB)
FOR DAMAGING WINDS, BUT AN INVERTED V PROFILE IN NAM SOUNDINGS
SUGGEST EVAPORATIVE COOLING COULD ENHANCE WIND GUSTS. MOST OF THIS
ACTIVITY SHOULD BE OVER BY 10 PM.
THE FRONT LIFTS NORTHWARD ON SUNDAY AS A LOW PRESSURE SYSTEM TRACKS
ACROSS THE CENTRAL PLAINS. THIS WILL KEEP OUR AREA IN A WARM SW FLOW
THROUGH THE LOW LEVELS, AND HIGHS ON SUNDAY WILL BE WELL ABOVE
NORMAL - IN THE LOWER TO MID 80S IN MOST SPOTS. THIS WILL BE WITHIN
A FEW DEGREES OF RECORD HIGHS - THE TRI RECORD OF 81 COULD BE TIED
OR BROKEN. THAT LOW PRESSURE SYSTEM AND ITS ASSOCIATED COLD FRONT
WILL CROSS OUR AREA ON MONDAY, WITH A LOW CHANCE OF SHOWERS/STORMS
AHEAD OF IT LATE SUNDAY NIGHT/MONDAY MORNING. INSTABILITY IN THE
MORNING APPEARS TOO LIMITED FOR ANY STRONG/SEVERE STORMS, AND THE
CHANCE OF SHOWERS WILL MAINLY BE NORTH OF I-40.
DAILY RECORD HIGH MAXIMUM TEMPERATURES
DATE CHATTANOOGA KNOXVILLE TRI-CITIES OAK RIDGE
03-22 89(1907) 87(1907) 81(1938) 83(2011)
A COLDER AIR MASS WILL BUILD INTO THE AREA ON MONDAY BEHIND THE COLD
FRONTAL PASSAGE. HIGH PRESSURE OVER THE GREAT LAKES AND OH VALLEY
REGION WILL PROMOTE DRIER AND SEASONALLY COOLER CONDITIONS THROUGH
TUESDAY. BY WEDNESDAY, BROAD RIDGING WILL EXPAND FROM THE SOUTHWEST
WITH HIGH PRESSURE SHIFTING EASTWARD, LEADING TO A RETURN OF
SOUTHERLY FLOW AND INCREASING MOISTURE AND WAA. LOW-END RAIN CHANCES
RETURN LATE IN THE WEEK AS A FRONT SETTLES SOMEWHERE IN THE TN/OH
VALLEY REGION. THE POSITION OF A LARGE HIGH PRESSURE RIDGE ACROSS
THE GULF COAST REGION WILL MEAN MOISTURE WILL BE LIMITED, BUT WE
COULD HAVE SEVERAL DAYS WITH RAIN CHANCES LATE IN THE WEEK AS THE
FRONT REMAINS NEARLY STATIONARY AND PARALLEL TO THE MIDLEVEL FLOW.
AVIATION
(18Z TAFS)
ISSUED AT 131 PM EDT SAT MAR 21 2026
MAIN QUESTION...WILL WE BREAK THE BOUNDARY LAYER CAP FOR MORE
ROBUST CONVECTION THIS EVENING AT TRI AND TYS. LATEST MESO-
ANALYSIS SHOWS MLCAPES INCREASING TO 500-1000 J/KG WITH A CAPPING
INVERSION NEAR 800-850MB. IF THE ENVIRONMENT DOES BREAK THE CAP,
THERE IS A THREAT OF HAIL AND STRONG/GUSTY WINDS. MID-LEVEL LAPSE
RATES NEAR 7 DEGREES/C AND RELATIVE GOOD CAPE IN THE HAIL GROWTH
REGION TO PRODUCE UP TO QUARTER SIZE HAIL. ALSO, MID-LEVEL AND
BOUNDARY LAYER DRY AIR TO SUPPORT LOCALIZED STRONG DOWNBURSTS.
THIS ACTIVITY WILL END BY AROUND MIDNIGHT OR THEREAFTER.
BESIDES THE WIDELY SCATTERED TO SCATTERED CONVECTION, HREF AND
LATEST DETERMINISTIC MODELS SHOW POTENTIAL OF LOW-CLOUD
DEVELOPMENT PRODUCING IFR/LIFR CONDITIONS AT TRI EARLY SUNDAY
MORNING.
PRELIMINARY POINT TEMPS/POPS
CHATTANOOGA AIRPORT, TN 58 86 62 74 / 10 0 10 0
KNOXVILLE MCGHEE TYSON AIRPORT, TN 60 84 58 67 / 40 0 20 10
OAK RIDGE, TN 58 84 58 68 / 40 0 30 10
TRI CITIES AIRPORT, TN 55 80 54 62 / 20 0 50 20
MRX WATCHES/WARNINGS/ADVISORIES
NC...NONE.
TN...NONE.
VA...NONE.
DISCUSSION...DH
AVIATION...DH
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