613
FXUS64 KMRX 080158 AAA
AFDMRX
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE MORRISTOWN TN
958 PM EDT WED MAY 7 2025
..NEW UPDATE
UPDATE
ISSUED AT 949 PM EDT WED MAY 7 2025
CURRENTLY, SCATTERED AREA OF SHOWERS HAVE DEVELOPED ALONG AND
NORTH OF INTERSTATE 40. THIS IS DUE TO ISENTROPIC LIFT AROUND THE
700MB LEVEL WHICH IS DEPICTED BY HREF, HRRR, AND LATEST
DETERMINISTIC MODELS TO CONTINUE THROUGH MUCH OF THE NIGHT.
INSTABILITY IS QUITE LIMITED AND ELEVATED. ISOLATED THUNDER IS
POSSIBLE BUT MAINLY JUST SHOWERS.
OTHERWISE, A GRADUAL MOISTENING OF THE BOUNDARY LAYER OVERNIGHT
WITH PATCHY FOG POSSIBLE AREA-WIDE. CURRENT MIN TEMPERATURE
FORECAST LOOKS GOOD.
SHORT TERM
(THIS EVENING THROUGH THURSDAY)
ISSUED AT 225 PM EDT WED MAY 7 2025
KEY MESSAGES:
1. A FEW TO POSSIBLY SEVERAL STRONG TO SEVERE STORMS ARE EXPECTED
TOMORROW AFTERNOON AND INTO THE EVENING HOURS. MOST OF OUR AREA HAS
BEEN INCLUDED IN THE LATEST DAY 2 SLIGHT RISK AREA FROM SPC. THE
MAIN WINDOW OF CONCERN WILL BE FROM ROUGHLY 4 PM THROUGH 10 PM. HAIL
UP TO 1.5 INCHES AND ISOLATED DAMAGING WINDS UP TO 65 MPH ARE POSSIBLE
WITH THE STRONGEST STORMS.
DISCUSSION:
TONIGHT, WE WILL SEE ON AND OFF SCATTERED SHOWERS MOVE THROUGH THE
AREA. ISOLATED TO PATCHY FOG IS LIKELY ACROSS AREAS THAT SEE RAIN
OVERNIGHT.
THURSDAY, A FEW TO POSSIBLY SEVERAL STRONG TO SEVERE STORMS ARE
EXPECTED. THE MAIN WINDOW OF CONCERN IS FROM ROUGHLY 4 PM THROUGH
10 PM. AN OVERVIEW OF THE SETUP IS AS FOLLOWS. AN UPPER LOW WILL
BE TO OUR WEST-NORTHWEST. A SURFACE LOW WILL BE IN PLACE SOMEWHERE
ACROSS WESTERN TN WITH AN ASSOCIATED WARM FRONT JUST SOUTH OF OUR
AREA. SOUTHWEST FLOW IN THE LOW TO MID LEVELS WILL ALLOW
DEWPOINTS TO CLIMB INTO THE LOW TO MID 60S. A COLD FRONT WILL BE
TO OUR NORTH AND MOVING SOUTH OUT OF KY. DUE TO THE ADVANCING
COLD FRONT, VORTICITY ASSOCIATED WITH THE UPPER LOW TO OUR
WEST, MODERATELY FAVORABLE UPPER JET DYNAMICS, INCREASING
MOISTURE, AND MODERATE 0-6KM EFFECTIVE BULK SHEAR, A FEW STRONG TO
SEVERE STORMS ARE EXPECTED.
ANY ONGOING SHOWERS TOMORROW MORNING SHOULD END BY MID TO LATE
MORNING. THEN, SKIES SHOULD BEGIN TO SLOWLY CLEAR INTO THE AFTERNOON
HOURS. SOUNDINGS SHOW A MID-LEVEL CAP IN PLACE THROUGH MID
AFTERNOON, BUT THEN ERODING. MLCAPE VALUES ARE EXPECTED TO BE AROUND
1500 J/KG ALONG WITH 30 TO 40 KTS OF EFFECTIVE SHEAR. HOWEVER, SHEAR
IN THE LOWER LEVELS OF THE ATMOSPHERE WILL BE ON THE WEAKER SIDE
WITH 0-1KM SHEAR ONLY AROUND 10 KTS.
THE MAIN THREAT WITH TOMORROW'S STORMS WILL BE HAIL AND ISOLATED
DAMAGING WINDS. THOUGH WE WILL LIKELY SEE WEAK, MID-LEVEL,
ROTATION IN SOME OF THE STRONGER STORMS, THE TORNADO THREAT IS
VERY LOW DUE TO THE WEAKER SHEAR IN THE LOWEST LEVELS. HAIL UP TO
1.5 INCHES IS POSSIBLE IN THE STRONGEST STORMS WITH WINDS UP TO
65 MPH. THE LARGER HAIL THREAT IS DUE TO THE FAVORABLE LAPSE
RATES, A GOOD AMOUNT OF CAPE IN THE HAIL GROWTH ZONE, AND THE 30
TO 40 KTS OF SHEAR THAT WILL BE IN PLACE.
LONG TERM
(THURSDAY NIGHT THROUGH NEXT WEDNESDAY)
ISSUED AT 225 PM EDT WED MAY 7 2025
KEY MESSAGES:
1. DAILY RAIN CHANCES EXPECTED MAINLY IN THE AFTERNOON AND EVENING
THROUGH SUNDAY.
2. HIGH RAIN CHANCES MONDAY AND TUESDAY AS A CUT-OFF LOW MOVES INTO
THE REGION FROM THE SOUTHWEST.
DISCUSSION:
THROUGH THE WEEKEND...
IN THE UPPER LEVELS, A CUT-OFF LOW WILL BE OVER THE EASTERN GREAT
LAKES THURSDAY NIGHT, SLOWLY DRIFTING SOUTH OVER PA ON FRIDAY. THIS
FEATURE WILL MOVE INTO THE NORTHEAST BY SATURDAY. AT THE SURFACE,
HIGH PRESSURE OVER THE MIDWEST WILL DRIFT TOWARDS THE NORTHEAST BY
SUNDAY. A DISTURBANCE OVER THE GULF COAST IS CAUSED BY A CUT-OFF LOW
THAT IS NEARLY STATIONARY NEAR LA. MOST OF THAT ACTIVITY WILL STAY
TO OUR SOUTH THROUGH THE WEEKEND. POPS OF 40% TO 80% ARE EXPECTED
FRIDAY AS THE GREAT LAKES TROUGH DIPS SOUTH BUT SHOWERS AND STORMS
WILL BE MAINLY DURING MAX HEATING.
ON SATURDAY AND SUNDAY, SHOWERS AND STORMS WILL BE ISOLATED TO
SCATTERED AND MAINLY DURING MAX HEATING. THE SOUTHERN HALF OF THE
REGION WILL HAVE THE HIGHEST CHANCES (AROUND 50%) SINCE IT IS CLOSER
TO THE GULF DISTURBANCE.
MONDAY AND TUESDAY...
THE CUT-OFF LOW OVER THE LOWER MISSISSIPPI VALLEY STARTS TO MOVE
EAST ON MONDAY. THE TROUGH WILL BE OVER THE REGION BY TUESDAY. WITH
HIGH PRESSURE OVER THE ATLANTIC, LOW LEVEL FLOW WILL BE SOUTHERLY.
DEEP LAYER MOISTURE ADVECTION IS LIKELY WITH THE TROUGH PULLING IN
GULF MOISTURE AT HIGHER LEVELS ALSO. THEREFORE, SCATTERED TO
NUMEROUS SHOWERS AND STORMS ARE LIKELY MONDAY AND TUESDAY.
TEMPS WILL BE NEAR NORMAL OR SLIGHTLY BELOW NORMAL WITH HIGHS IN THE
70S AND LOWS IN THE 50S.
AVIATION
(00Z TAFS)
ISSUED AT 729 PM EDT WED MAY 7 2025
MVFR CONDITIONS AT CHA DUE TO CEILING WILL SPREAD NORTH TOWARD TYS
BY LATE THIS EVENING AS MOISTURE AND ISENTROPIC LIFT SPREADS
NORTHEAST. SCATTERED SHOWERS ARE POSSIBLE AT CHA AND TYS DURING
THE NIGHT AND POSSIBLY AT TRI TOWARD MORNING.
FOR THURSDAY, LOW-LEVEL MOISTURE ERODES IN THE MORNING ALLOWING
FOR A RETURN OF VFR CONDITIONS AT ALL TAF SITES. BY LATE IN THE
FORECAST PERIOD, INCREASING INSTABILITY AND JET FORCING WILL
PRODUCE SCATTERED THUNDERSTORMS. SOME OF THESE STORMS COULD BE
SEVERE LATE IN THE FORECAST PERIOD AND INTO THE EVENING HOURS.
PRELIMINARY POINT TEMPS/POPS
CHATTANOOGA AIRPORT, TN 59 80 60 77 / 30 60 50 50
KNOXVILLE MCGHEE TYSON AIRPORT, TN 58 78 58 75 / 40 70 60 60
OAK RIDGE, TN 57 78 58 75 / 40 70 60 50
TRI CITIES AIRPORT, TN 55 77 55 73 / 30 60 60 50
MRX WATCHES/WARNINGS/ADVISORIES
NC...NONE.
TN...NONE.
VA...NONE.
SHORT TERM...DH
LONG TERM....MCD
AVIATION...DH
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