709
FXUS64 KMRX 281718
AFDMRX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MORRISTOWN TN
118 PM EDT TUE JUL 28 2026
..NEW DISCUSSION, AVIATION
KEY MESSAGES
UPDATED AT 117 PM EDT TUE JUL 28 2026
- POTENTIAL FOR ISOLATED TO SCATTERED STRONG TO POSSIBLY SEVERE
SHOWERS AND THUNDERSTORMS THROUGH THIS EVENING, PRIMARILY IMPACTING
NORTHEAST TENNESSEE INTO SOUTHWEST VIRGINIA. DAMAGING WINDS ARE THE
PRIMARY THREAT WITH ISOLATED FLASH FLOODING. LOW-END THREAT FOR
SEVERE HAIL OR TORNADIC ACTIVITY.
- HEAT ADVISORY CONTINUES FOR THE SOUTHERN TN VALLEY THIS AFTERNOON
WITH HEAT INDEX VALUES AROUND 105.
- DRY WEATHER WITH MORE MODERATE TEMPS/HUMIDITY FROM WEDNESDAY
THROUGH FRIDAY.
- A WET PATTERN RETURNS FOR THE WEEKEND INTO NEXT WEEK.
DISCUSSION
ISSUED AT 117 PM EDT TUE JUL 28 2026
A COMPLEX SITUATION OF VARIOUS BOUNDARIES, STABLE LAYERS, AND UPPER
LEVEL FORCING LEAD TO LOW CONFIDENCE IN THE DETAILS OF HOW
CONVECTION WILL EVOLVE THROUGH THE REST OF THE AFTERNOON AND
EVENING. A LINEAR BOUNDARY IS EVIDENT IN SATELLITE, STRETCHING FROM
NEAR NASHVILLE TO OUR KY/VA BORDER COUNTIES, WITH ANOTHER BOUNDARY
LOCATED FARTHER NORTH ACROSS SOUTH CENTRAL AND EASTERN KY.
CONVECTIVE TOWERS ARE NOTED IN THE KY/VA BORDER AREA WITH THESE
BOUNDARIES. MORNING CONVECTION IN NE TN HAS CREATED A THERMAL
BOUNDARY BETWEEN KNOXVILLE AND MORRISTOWN FROM STORM OUTFLOW AND
DIFFERENTIAL HEATING FROM CLOUD COVER. SATELLITE SHOWS CLEARING
NORTHEAST OF THIS BOUNDARY, SO THE AIR MASS IN NE TN AND SW VA
SHOULD RECOVER MOST ITS INSTABILITY. SOUTH AND WEST OF THIS
BOUNDARY, THE AIR MASS APPEARS TO BE CAPPED. ALOFT, AN UPPER JET
NOSE IS OVER OUR NE SECTIONS, WITH 500 MB VORTICITY IN THAT AREA AS
WELL.
THE BOTTOM LINE OF THESE FEATURES IS THAT A SECOND ROUND OF
SHOWERS/STORMS IS EXPECTED IN OUR NE SECTIONS WHERE THE UPPER
FORCING AND SURFACE BOUNDARIES CAN INTERACT. BULK EFFECTIVE SHEAR OF
35-40 KT AND MLCAPE OF 2000-3000 J/KG THIS AFTERNOON WILL MEAN A
THREAT OF SEVERE STORMS, WITH DAMAGING WINDS AS THE PRIMARY THREAT,
AND A LESSER BUT NON-ZERO THREAT OF LARGE HAIL AND AN ISOLATED
TORNADO. SOME OF THIS ACTIVITY COULD MAKE IT INTO THE CENTRAL TN
VALLEY, IF MESOSCALE FORCING FROM OUTFLOW BOUNDARIES CAN OVERCOME
MIDLEVEL CAPPING - THE SOUTHERN AND WESTERN EXTENT OF CONVECTION IS
A BIG QUESTION MARK. AGAIN, THE MAIN THREAT AREA IS LIKELY EAST OF I-
75 AND NORTH OF I-40. FLASH FLOODING WILL BE A CONCERN WHERE
TRAINING OF STORMS OCCURRS, ESPECIALLY IN NE TN/SW VA WHERE 1-HR FFG
IS ONLY 1.3-1.5 INCHES. STORM MOTION FROM NW TO SE MAY ALIGN WITH
RESIDUAL BOUNDARIES FROM THE MORNING CONVECTION, LEADING TO TRAINING
CELLS WITH HIGH RAINFALL RATES.
WEDNESDAY THROUGH FRIDAY WILL FEATURE SOME VERY PLEASANT CONDITIONS
FOR THE START OF AUGUST. WITH A TROUGH OVER THE ATLANTIC COAST AND A
NORTHERLY FLOW ACROSS OUR AREA, TEMPERATURES WILL DROP SLIGHTLY
BELOW NORMAL. HUMIDITY WILL ALSO TREND LOWER INTO THURSDAY BEFORE A
TREND UPWARD BEGINS FRIDAY - AFTERNOON DEWPOINTS WILL BE IN THE 60S,
AND SOME LOW TEMPS IN THE 50S WILL BE POSSIBLE IN NORTHERN SECTIONS.
A WET PATTERN MAY DEVELOP AGAIN OVER THE WEEKEND AS A CLOSED UPPER
LOW DROPS SW FROM THE UPPER PLAINS INTO THE MID MS-OH VALLEY REGION
AND STAYS PARKED TO OUR WEST THROUGH THE REST OF THE FORECAST
PERIOD. A DEEP SOUTHERLY FLOW FROM THE GULF WILL PROVIDE RAIN
CHANCES EACH DAY FROM SATURDAY THROUGH TUESDAY.
AVIATION
(18Z TAFS)
ISSUED AT 117 PM EDT TUE JUL 28 2026
SHOWERS/STORMS ARE EXPECTED AT TRI THIS AFTERNOON, WITH LESSER RAIN
CHANCES AT TYS. CHA IS EXPECTED TO REMAIN DRY IN A MORE STABLE
ENVIRONMENT. CONFDIENCE IS LOW REGARDING TIMING OF STORMS, SO WILL
CARRY TEMPO/PROB30 FOR MUCH OF THE AFTERNOON AND EVENING AT
TRI/TYS. WITH TRI HAVING THE BEST CHANCE OF SEEING RAIN TODAY,
WILL HAVE LOW CIGS DEVELOPING THERE LATER TONIGHT. THIS COULD ALSO
HAPPEN AT TYS IF RAIN OCCURS THERE. A DRIER AIR MASS BUILDS IN
TOMORROW WITH A N-NE WIND, AND SHOULD DISSIPATE ANY MORNING CLOUD
COVER BY 18Z.
PRELIMINARY POINT TEMPS/POPS
CHATTANOOGA AIRPORT, TN 73 90 67 88 / 20 0 0 0
KNOXVILLE MCGHEE TYSON AIRPORT, TN 71 87 64 85 / 40 0 0 0
OAK RIDGE, TN 69 87 64 86 / 20 0 0 0
TRI CITIES AIRPORT, TN 66 82 59 82 / 40 0 0 0
MRX WATCHES/WARNINGS/ADVISORIES
NC...NONE.
TN...NONE.
VA...NONE.
DISCUSSION...DGS
AVIATION...DGS
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