907
FXUS64 KMRX 171120
AFDMRX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MORRISTOWN TN
720 AM EDT THU APR 17 2025
..NEW AVIATION
SHORT TERM
(TODAY AND TONIGHT)
ISSUED AT 219 AM EDT THU APR 17 2025
KEY MESSAGES:
1. PERHAPS SOME LIGHT RAIN POSSIBLE IN THE NORTH TODAY?
2. OTHERWISE ANOTHER DRY DAY WITH LOW RH VALUES EXPECTED FOR MOST
AREAS TODAY.
DISCUSSION:
RIDGING BEGINS TO BUILD ACROSS THE OHIO AND TENNESSEE VALLEYS TODAY,
STARTING WHAT WILL BE A SIGNIFICANT WARM UP AS WE HEAD INTO THE
WEEKEND. FURTHER WEST, A SURFACE LOW WILL EJECT NORTHEAST OUT OF
COLORADO TODAY. BROAD SOUTHERLY FLOW DEVELOPS FROM THE CENTRAL
PLAINS ACROSS THE MISSISSIPPI VALLEY AND INTO THE SOUTHEAST IN
RESPONSE, SPURRING A WARM TO MOVE ENE FROM THE OZARKS INTO OHIO
VALLEY THIS AFTERNOON AND EVENING. WHILE MOST OF THE AREA WILL
REMAIN DRY TODAY, THERE'S PLENTY OF SUPPORT FROM VARIOUS SOURCES FOR
SOME LIGHT RAIN TO AFFECT AREAS FROM THE NORTHERN PLATEAU INTO
NORTHEAST TN AND OUR VIRGINIA COUNTIES THIS AFTERNOON AND
EVENING. I DO HAVE SOME LOW-END SLIGHT CHANCES IN THOSE AREAS
TODAY, EXPECTING SOME LIGHT RAIN/SPRINKLES BUT NOTHING MORE. THEN
AGAIN, IT COULD VERY EASILY WIND UP BEING DRY AS WE HAVE A
RETREATING DRY AIR MASS IN PLACE.
SPEAKING OF DRY AIR, ANY RAINFALL WE HAVE WOULD BE WORKING TO
MOISTEN THE DRY AIR MASS IN PLACE. AS SUCH, I THINK WE'LL SEE
ANOTHER DAY WITH AFTERNOON RH VALUES DIPPING BELOW 30 PERCENT
AGAIN, ESPECIALLY FOR AREAS NEAR/SOUTH OF THE I-40 CORRIDOR. THE
RAINFALL, WHATEVER THAT MAY LOOK LIKE, DOESN'T ARRIVE UNTIL AROUND
OR AFTER PEAK HEATING SO LOW RH'S SEEM A GOOD BET. EXPECT MILDER
TEMPERATURES TONIGHT, ESPECIALLY IN THE FOOTHILLS AND MIDSLOPE
AREAS OF THE TN MOUNTAINS.
LONG TERM
(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 219 AM EDT THU APR 17 2025
KEY MESSAGES:
1. AN ISOLATED THUNDERSTORM OR TWO POSSIBLE SUNDAY AFTERNOON, MEDIUM
CHANCES FOR ADDITIONAL SHOWERS AND THUNDERSTORMS LATE SUNDAY NIGHT
THROUGH MONDAY.
2. LOW CHANCES FOR ADDITIONAL DIURNAL RAIN SHOWERS BEYOND MONDAY.
DISCUSSION:
FRIDAY AND SATURDAY LOOK TO BE THE BEST DAYS HEADING INTO THE
WEEKEND, WITH A BUILDING OFFSHORE RIDGE HELPING TO INFLUENCE THE
SOUTHEASTERN U.S. WEATHER PATTERN, INCLUDING BRINGING WARM AIR
ACROSS THE REGION. BY SUNDAY, AN UPPER TROUGH WILL BE DIGGING INTO
THE PLAINS, HELPING POWER SIGNIFICANT WEATHER FAR TO OUR WEST. GFS
SOUNDINGS SHOW AN UNCAPPED ATMOSPHERE SUNDAY AFTERNOON, BUT WITH
ONLY LOW AMOUNTS OF CAPE AVAILABLE IN THE SHEARED ATMOSPHERE. WITH
THE MAIN FRONTAL SYSTEM STILL OFF TO THE WEST, AN ISOLATED
THUNDERSTORM OR TWO BUILDING ON THE HIGHER TERRAIN WOULD BE THE
LIKELY OUTCOME - WHICH THE ENSEMBLES ACTUALLY DEPICT VERY WELL.
HEADING INTO MONDAY THE MATURING AND OCCLUDING LOW WILL BE UP IN THE
GREAT LAKES, AND BOTH THE EURO AND GFS DEPICT A COLD FRONT
STRUGGLING TO MAKE ANY SOUTHERN PROGRESS AS IT MOVES LATERALLY FROM
THE WEST TO THE EAST. GFS STILL CLASSICALLY DEPICTS A QUICKER
ARRIVAL OF THE SHOWERS AND STORMS THAN THE EURO, IN THIS CASE THE
EURO'S LATER ARRIVAL INTO DAYTIME MONDAY WOULD ALLOW FOR A STRONGER
THUNDERSTORM ENVIRONMENT WITH MORE AVAILABLE CAPE THAN THE GFS
NIGHTTIME ARRIVAL. ONCE THE DECAYING FRONTAL SYSTEM CLEARS OUT
SOMETIME ON TUESDAY, GUIDANCE HAS VERY LOW RAIN CHANCES INTO
MIDWEEK, OUTSIDE OF A DIURNAL PULSE. SEEMS INCREASINGLY LIKELY THAT
EVEN AS THE UPPER OFFSHORE RIDGE FLATTENS OUT NEXT WEEK THAT WE WILL
MAINTAIN OUR WARM AIRMASS WITH THE MAIN JET STREAM LOCATED FAR TO
OUR NORTH.
AVIATION
(12Z TAFS)
ISSUED AT 718 AM EDT THU APR 17 2025
VFR AT ALL TAF SITES TODAY AND TONIGHT. LIGHT WINDS. HIGH
AFTERNOON CLOUDS, VERY LOW CHANCE OF A SPRINKLE, BUT NO IMPACTS
EXPECTED.
PRELIMINARY POINT TEMPS/POPS
CHATTANOOGA AIRPORT, TN 77 54 84 60 / 0 0 0 0
KNOXVILLE MCGHEE TYSON AIRPORT, TN 74 52 83 62 / 0 0 0 0
OAK RIDGE, TN 72 51 82 60 / 10 0 0 0
TRI CITIES AIRPORT, TN 69 49 81 54 / 20 10 0 0
MRX WATCHES/WARNINGS/ADVISORIES
NC...NONE.
TN...NONE.
VA...NONE.
SHORT TERM...CD
LONG TERM....WELLINGTON
AVIATION...WELLINGTON
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