556
ACUS11 KWNS 202213
SWOMCD
SPC MCD 202213
VAZ000-KYZ000-TNZ000-NCZ000-GAZ000-202315-
MESOSCALE DISCUSSION 0910
NWS STORM PREDICTION CENTER NORMAN OK
0513 PM CDT TUE MAY 20 2025
AREAS AFFECTED...SOUTHERN APPALACHIANS
CONCERNING...SEVERE POTENTIAL...WATCH LIKELY
VALID 202213Z - 202315Z
PROBABILITY OF WATCH ISSUANCE...80 PERCENT
SUMMARY...A SEVERE THREAT IS EXPECTED TO DEVELOP ACROSS PARTS OF THE
SOUTHERN APPALACHIANS OVER THE NEXT COUPLE OF HOURS. TORNADOES, WIND
DAMAGE AND ISOLATED LARGE HAIL WILL BE POSSIBLE. WEATHER WATCH
ISSUANCE WILL LIKELY BE NEEDED.
DISCUSSION...LATEST MOSAIC RADAR IMAGERY SHOWS A RELATIVELY LARGE
CLUSTER OF SEVERE STORMS OVER THE TENNESSEE VALLEY. AHEAD OF THE
STORMS, A MODERATELY UNSTABLE AIRMASS IS IN PLACE. FURTHER EAST,
INTO EASTERN TENNESSEE AND EASTERN KENTUCKY, THE AIRMASS WAS
NEGATIVELY IMPACTED BY A LINE OF THUNDERSTORMS EARLIER TODAY. IN THE
WAKE OF THESE STORMS, AIRMASS RECOVERY IS TAKING PLACE, AND SURFACE
TEMPERATURES HAVE ALREADY INCREASED INTO THE MID TO UPPER 70S ALONG
THE I-75 CORRIDOR FROM NEAR LEXINGTON SOUTHWARD TO KNOXVILLE. AS
SURFACE HEATING CONTINUES, MODERATE INSTABILITY IS EXPECTED TO
RE-DEVELOP ALONG MUCH OF THIS CORRIDOR. THIS WILL CONTRIBUTE TO A
SEVERE THREAT THIS EVENING, AS THE STORMS OVER MIDDLE TENNESSEE AND
WESTERN KENTUCKY MOVE EASTWARD.
REGIONAL WSR-88D VWPS AT JACKSON, KY AND MORRISTOWN, TN HAVE 0-6 M
SHEAR IN THE 35 TO 40 KNOT RANGE. THE JACKSON VWP HAS 0-3 KM
STORM-RELATIVE HELICITY NEAR 400 M2/S2. AS CELL COVERAGE STARTS TO
INCREASE, THIS ENVIRONMENT SHOULD SUPPORT A TORNADO, WIND-DAMAGE
THREAT AND ISOLATED LARGE HAIL THREAT. IF A CELL CAN REMAIN DISCRETE
AND BECOME DOMINANT, THEN A LOCALLY GREATER TORNADO THREAT WOULD BE
POSSIBLE. IT ALSO REMAINS POSSIBLE THAT STORMS WILL CONGEAL INTO ONE
OR MORE SHORT-LINE SEGMENTS. IF THAT WERE TO OCCUR, THEN THE
WIND-DAMAGE THREAT WOULD INCREASE AS THE STORMS MOVE INTO THE AREA
FROM THE WEST.
..BROYLES/GLEASON.. 05/20/2025
..PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT
ATTN...WFO...GSP...MRX...JKL...FFC...LMK...OHX...
LAT...LON 35238489 34898465 34878416 35618325 36538293 37418291
37838311 38078355 38208432 38078466 37828490 37428492
36668485 35658489 35238489
MOST PROBABLE PEAK TORNADO INTENSITY...120-150 MPH
MOST PROBABLE PEAK WIND GUST...55-70 MPH
MOST PROBABLE PEAK HAIL SIZE...1.00-1.75 IN
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