322
FXUS64 KMRX 070004
AFDMRX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MORRISTOWN TN
804 PM EDT TUE MAY 6 2025
..NEW AVIATION
SHORT TERM
(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 311 PM EDT TUE MAY 6 2025
KEY MESSAGES:
1. DRY TONIGHT WITH NEAR NORMAL LOWS.
2. PRECIPITATION CHANCES INCREASE BY EARLY WEDNESDAY MORNING.
DISCUSSION:
THE MAIN ITEM UP FOR DISCUSSION IS WEDNESDAY'S RAIN CHANCES. MOST
MODELS HAVE SHIFTED THE PRECIP SLIGHTLY FURTHER NORTH. IT LOOKS
LIKE THE TROUGH BASE TO OUR NORTHEAST WILL BE A LITTLE MORE BROAD
AND FLAT THAN PREVIOUSLY DEPICTED. THIS WILL ALLOW OUR SOUTHERN
STREAM SYSTEM TO PUSH FURTHER NORTH INTO OUR AREA.
THE BEST CHANCES FOR PRECIP ARE STILL ACROSS THE EXTREME SOUTHERN
TN VALLEY AND SOUTHWEST NC. HOWEVER, IT NOW LOOKS LIKE LIGHT RAIN
SHOWERS MAY PUSH AS FAR NORTH AS THE MORRISTOWN AREA. PREVIOUSLY,
IT LOOKED MOSTLY DRY SOUTH OF I-40. MOST LOCATIONS WILL SEE LESS
THAN A TENTH OF AN INCH OF PRECIP. AROUND A QUARTER OF AN INCH IS
EXPECTED ACROSS PARTS OF SEQUATCHIE, MARION, HAMILTON, AND
BRADLEY COUNTIES. A FEW RUMBLES OF THUNDER MAY ACCOMPANY THE RAIN
BUT MOSTLY SHOWERS ARE EXPECTED.
LONG TERM
(WEDNESDAY NIGHT THROUGH NEXT TUESDAY)
ISSUED AT 311 PM EDT TUE MAY 6 2025
KEY MESSAGES:
1. IT SEEMS LIKELY WE'LL TRANSITION FROM ONE BLOCKING PATTERN IN THE
SHORT TERM TO A DIFFERENT TYPE IN THE LONG TERM. AS SUCH, UNCERTAINTY
IS SOMEWHAT HIGH FOR THE PERIOD, MAINLY WITH REGARDS TO RAIN CHANCES.
2. THAT SAID, FAIRLY HIGH CONFIDENCE IN WIDESPREAD RAIN CHANCES ON
THURSDAY INTO FRIDAY.
DISCUSSION:
WEDNESDAY NIGHT INTO THURSDAY, THE WESTERN UPPER LOW AND REMNANT
PIECE OF A DECAYING OMEGA BLOCK BEGINS TO OPEN UP OVER THE OZARKS AS
A TROUGH DROPS SOUTHEAST THROUGH QUEBEC AND INTO THE NORTHEASTERN US
AREA. UPPER RIDGING THEN BUILDS NORTHEAST FROM THE DESERT SOUTHWEST,
INTO THE UPPER MIDWEST AND WESTERN GREAT LAKES REGION BY LATE THU
AFTERNOON. ALL OF THIS PUSHES A FRONT SOUTH THROUGH THE AREA ON THU,
PROVIDING DECENT CHANCES FOR WIDESPREAD RAINFALL ACROSS THE FORECAST
AREA.
HOW THE PATTERN EVOLVES FROM HERE IS A LITTLE UNCERTAIN. MOST ALL
GUIDANCE TRANSITION THE QUEBEC TROUGH INTO A CLOSED LOW OVER NY AND
PA BY FRI AFTERNOON. THE UNCERTAINTY REVOLVES AROUND WHAT HAPPENS
WITH THE AFOREMENTIONED WESTERN LOW. SOME GUIDANCE TAKES THIS BACK
TO A CLOSED UPPER LOW OVER THE ARKLATEX WHILE OTHERS KEEP IS AS A
NEARLY CLOSED LOW OVER THE CENTRAL GULF COAST BY LATE FRI. THE
LATTER IS A MORE PROGRESSIVE PATTERN WHICH WOULD YIELD DRY, OR AT
LEAST DRYING, CONDITIONS LOCALLY FRIDAY INTO THE WEEKEND.
CONVERSELY, THE FORMER WOULD KEEP SOME RAIN CHANCES AROUND THROUGH
THE WEEKEND, FAVORING THE SOUTHERN AREAS. GIVEN HOW EVEN THE
PROGRESSIVE DETERMINISTIC GUIDANCE SHOWS RIDGING EXTENDING FROM THE
DESERT SOUTHEAST INTO THE WESTERN GREAT LAKES, AS WELL AS AN
EVENTUAL CUTOFF LOW FORMING FURTHER SOUTHEAST, I'M NOT INCLINED TO
STRAY FROM THE NBM, WHICH FEATURES CONTINUED CHANCE POPS OVER THE
SOUTHERN TWO THIRDS OF THE FORECAST AREA THROUGH THE WEEKEND. THESE
BLOCKING PATTERNS ARE NOTORIOUS FOR NOT MOVING AS QUICKLY AS
FORECAST SO I DON'T WANT TO DRY THINGS OUT AS QUICKLY AS SOME
GUIDANCE WOULD SUGGEST. OTHERWISE, THE CONTINUED ODDS FOR CLOUDY
AND/OR RAINY CONDITIONS SHOULD KEEP TEMPERATURES WITHIN A COUPLE OF
DEGREES FROM SEASONAL NORMS.
AVIATION
(00Z TAFS)
ISSUED AT 754 PM EDT TUE MAY 6 2025
A WEAK FRONTAL SYSTEM WILL LIFT NORTH BEFORE 12Z TOMORROW,
ESPECIALLY AT CHA. LOWER CIG, POSSIBLY VSBY, AND -SHRA WILL
APPEAR FROM SOUTH TO NORTH AT CHA AND TYS. THUNDER LOOKS LOW, BUT
WOULD BEST BE SEEN AT CHA, BUT IS LEFT OUT OF THE TAF FOR NOW.
SHRA LOOKS TO MOVE OUT/DISSIPATE IN THE AFTERNOON, BUT LOWER CIG
MAY REMAIN. ASIDE FROM THIS SYSTEM, TRI MAY UNDERGO IFR FOG
OVERNIGHT DUE TO HANGING ONTO CLEARER SKIES LONGER AND RECENT
MOISTURE FROM THIS MORNING.
PRELIMINARY POINT TEMPS/POPS
CHATTANOOGA AIRPORT, TN 56 69 59 78 / 30 70 40 50
KNOXVILLE MCGHEE TYSON AIRPORT, TN 52 70 57 77 / 10 50 30 50
OAK RIDGE, TN 51 72 56 77 / 10 40 30 50
TRI CITIES AIRPORT, TN 46 73 53 76 / 0 20 20 50
MRX WATCHES/WARNINGS/ADVISORIES
NC...NONE.
TN...NONE.
VA...NONE.
SHORT TERM...
AVIATION...KS
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