379
ACUS11 KWNS 181155
SWOMCD
SPC MCD 181154
KYZ000-TNZ000-ALZ000-MSZ000-ARZ000-181430-
MESOSCALE DISCUSSION 2272
NWS STORM PREDICTION CENTER NORMAN OK
0554 AM CST WED DEC 18 2024
AREAS AFFECTED...TENNESSEE VALLEY AREA
CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY
VALID 181154Z - 181430Z
PROBABILITY OF WATCH ISSUANCE...20 PERCENT
SUMMARY...A STRONG WIND GUST OR TWO, OR EVEN A VERY BRIEF/WEAK
TORNADO, WILL BE POSSIBLE ACROSS THE TENNESSEE VALLEY AREA THIS
MORNING AS A LINE OF STORMS PROGRESSES ACROSS THE REGION. WW
ISSUANCE IS UNLIKELY TO BE NEEDED.
DISCUSSION...LATEST RADAR LOOP SHOWS A SEMI-CONTINUOUS BAND OF
THUNDERSTORMS ADVANCING ACROSS WESTERN KENTUCKY/WESTERN TENNESSEE
AND THE ARKLATEX REGION EARLY THIS MORNING, NEAR AN ADVANCING COLD
FRONT. THE PRE-FRONTAL BOUNDARY LAYER IS CHARACTERIZED BY
TEMPERATURES IN THE LOW 60S, AND DEWPOINTS IN THE MID TO UPPER 50S
(KENTUCKY AND MOST OF TENNESSEE) TO THE LOW 60S/NORTHERN
MISSISSIPPI). HOWEVER, THIS DEGREE OF BOUNDARY-LAYER THETA-E
REMAINS INSUFFICIENT TO ALLOW TRULY SURFACE-BASED CONVECTION, WITH A
WEAK STABLE LAYER INDICATED IN THE 900 TO 950MM LAYER.
ABOVE THE WEAK STABLE LAYER, MODEST ELEVATED CAPE (AROUND 500 J/KG)
IS INDICATED -- SUFFICIENT FOR WIDESPREAD LIGHTNING AND EVEN
VIGOROUS/BOWING SEGMENTS WITHIN THE LINE LOCALLY. WHILE THE
SLIGHTLY ELEVATED NATURE OF THE CONVECTION SHOULD CONTINUE TO LIMIT
OVERALL SEVERE POTENTIAL, THE MOST ORGANIZED SEGMENTS WITHIN THE
LINE WILL BE CAPABLE OF PRODUCING GUSTY WINDS -- PERHAPS NEAR SEVERE
LEVELS LOCALLY. EVEN A VERY BRIEF/WEAK TORNADO CANNOT BE RULED OUT,
NEAR ONE OF THE EMBEDDED BOWING STRUCTURES. STILL, WITH STORMS
MOVING QUICKLY THROUGH THE TENNESSEE VALLEY AREA -- TOO SOON TO
ALLOW ANY APPRECIABLE PRE-CONVECTIVE DIURNAL HEATING TO OCCUR -- IT
APPEARS AT THIS TIME THAT RISK SHOULD REMAIN TOO LOW TO WARRANT WW
CONSIDERATION.
..GOSS/EDWARDS.. 12/18/2024
..PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT
ATTN...WFO...LMK...OHX...HUN...MEG...
LAT...LON 34799045 35888833 36718690 36808596 35998599 35508618
34808817 34538948 34539050 34799045
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