536
FXUS64 KMRX 111647
AFDMRX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MORRISTOWN TN
1247 PM EDT MON AUG 11 2025
..NEW DISCUSSION, AVIATION
DISCUSSION
ISSUED AT 1221 PM EDT MON AUG 11 2025
KEY MESSAGES:
1. RAIN SHOWERS THIS AFTERNOON/EVENING MAINLY TOWARDS THE
MOUNTAINS. DRIER, WITH A FEW SPRINKLES/LIGHT SHOWERS, FURTHER
NORTH AND WEST ACROSS THE FORECAST AREA.
2. MORE WIDESPREAD SCATTERED CONVECTION, LIMITED THUNDERSTORM
CHANCES, ON TUESDAY. TROPICAL-LIKE HEAVY RAIN RATES POSSIBLE,
ESPECIALLY ACROSS SOUTHEAST TENNESSEE NEAR CHATTANOOGA.
3. SHORTWAVE TROUGH AND SURFACE FRONT CONTINUE SCATTERED
PRECIPITATION CHANCES ON WEDNESDAY WITH SOME HEAVY RAIN RATES.
4. MOSTLY DIURNAL PRECIPITATION CHANCES THROUGH LATE WEEK WITH
WEAK FORCING AND UPPER-LEVEL RIDGE RETROGRADING WESTWARD TOWARDS
THE LOWER MISSISSIPPI VALLEY. HIGHEST PRECIPITATION CHANCES WILL
BE OVER THE HIGHER ELEVATIONS EACH AFTERNOON.
DISCUSSION:
A LOW PRESSURE SYSTEM WITH TROPICAL MOISTURE NEAR THE FLORIDA
PANHANDLE IS PRODUCING WIDESPREAD PRECIPITATION ACROSS THE
SOUTHEAST CONUS. DOWNSLOPE FLOW ACROSS THE MOUNTAINS IS LIMITING
THE PRECIPITATION COVERAGE ACROSS OUR AREA. RAIN IS LIKELY TO
CONTINUE ACROSS THE FAR EASTERN MOUNTAINS THIS EVENING AND TONIGHT
WITH INCREASING CHANCES LATE TONIGHT INTO TUESDAY MORNING NEAR
CHATTANOOGA.
THIS LOW PRESSURE SYSTEM WILL APPROACH OUR SOUTHEASTERN COUNTIES
ON TUESDAY AFTERNOON WITH WINDS BECOMING MORE SOUTH AND INCREASING
MOISTURE ADVECTING ACROSS THE AREA. PW VALUES INCREASE SUBSTANTIALLY.
RAP FORECAST SOUNDINGS SHOW PW VALUES AROUND 2.2 INCHES NEAR
CHATTANOOGA WITH A SATURATED ATMOSPHERE AND DEEP WARM CLOUD LAYER
DEPTH AROUND 14K FT. MLCAPE IS LIMITED NEAR 1000 J/KG WITH A VERY
SKINNY SOUNDING PROFILE SUPPORTIVE OF WEAK, DEEP UPDRAFTS. THIS
WILL SUPPORT TROPICAL WARM CLOUD RAIN PROCESSES WITH HEAVY RAIN
RATES AND THE POTENTIAL FOR URBAN AND SMALL STREAM FLOODING NEAR
THE SOUTHERN VALLEY, SOUTHERN PLATEAU, SOUTHWEST NORTH CAROLINA,
AND THE SOUTHERN EAST TENNESSEE MOUNTAINS.
SIMILAR SETUP ON WEDNESDAY AS A SHORTWAVE QUICKLY MOVES ACROSS THE
REGION WITH AN ALREADY SATURATED ENVIRONMENT. THIS WILL RESULT IN
SCATTERED SHOWERS, AND A FEW THUNDERSTORMS, WITH THE POTENTIAL FOR
HEAVY RAIN RATES AND LOCALIZED FLASH FLOODING AREA-WIDE AS PW
VALUES REMAIN 2.0 TO 2.2 INCHES ACROSS THE AREA.
PRECIPITATION CHANCES REMAIN THROUGH LATE WEEK AND INTO THE
WEEKEND, BUT UNCERTAINTY IS HIGHER DURING THE LATE WEEK TIME-
FRAME. LESS SYNOPTIC SUPPORT IS EXPECTED WITH PRIMARILY DIURNAL
TREND CONVECTION WITHIN AN ENVIRONMENT SUPPORTIVE OF HEAVY RAIN
RATES. MOST LIKELY PRECIPITATION CHANCES EACH DAY WILL BE ACROSS
THE HIGHER ELEVATIONS.
AVIATION
(18Z TAFS)
ISSUED AT 1221 PM EDT MON AUG 11 2025
VFR CIGS EXPECTED TO PREVAIL AND TYS AND TRI WITH DOWNSLOPE FLOW
ACROSS THE MOUNTAINS WITH MVFR CIGS SETTING UP AT CHA. TEMPO
MVFR/IFR VIS IS POSSIBLE DURING RAIN SHOWERS AT ALL SITES, BUT
PRIMARILY IMPACTING CHA TONIGHT. UPSLOPE SSE FLOW NEAR CHA WILL
RESULT IN LOW CIGS BY LATE TONIGHT AND TUESDAY MORNING WITH IFR
CONDITIONS PROBABLE NEAR THE TERMINAL. IN ADDITION, FOG MAY
DEVELOP LATE TONIGHT WITH THE POTENTIAL FOR IFR CIGS/VIS IN THE
VICINITY OF TRI. WINDS REMAIN LIGHT AND FROM THE SOUTHEAST.
PRELIMINARY POINT TEMPS/POPS
CHATTANOOGA AIRPORT, TN 73 85 72 89 / 30 80 50 80
KNOXVILLE MCGHEE TYSON AIRPORT, TN 72 86 72 87 / 30 70 50 60
OAK RIDGE, TN 72 87 72 87 / 20 70 50 70
TRI CITIES AIRPORT, TN 67 85 69 84 / 20 70 50 70
MRX WATCHES/WARNINGS/ADVISORIES
NC...NONE.
TN...NONE.
VA...NONE.
SHORT TERM...JB
LONG TERM....JB
AVIATION...JB
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