Severe Thunderstorm Warning 48, NWS Nashville, TN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NASHVILLE TN
845 PM CDT THU APR 21 2005

.DISCUSSION...SURFACE BOUNDARY DRAPED WEST TO EAST ACROSS CENTRAL
KENTUCKY THIS EVENING...THEN RUNS BACK UP NORTH OF SAINT LOUIS.
OTHER BOUNDARIES EXIST ACROSS SOUTHERN MISSOURI. LARGE TEMP
DIFFERENCE ACROSS KY BOUNDARY WITH 70 DEGS AT RUSSELL SPRINGS
KENTUCKY AND 57 DEGS AT LEXINGTON. OHX DOPPLER SHOWING
ISOLATED CONVECTION IN MID STATE THIS EVENING. MEMPHIS DOPPLER
RADAR SHOWING MORE ORGAINIZED CONVECTION WORKING GENERALLY EAST
THROUGH WESTERN TN AT 01Z WITH MORE STORMS BACK IN EASTERN ARKANSAS.
LOOKS LIKE CONVECTION MOVING THROUGH WESTERN TN WILL TRY AND GET
INTO BENTON COUNTY BY 900 PM CDT AND STEWART BY 930 PM. ALSO
ISOLATED STORMS ARE BEGINNING TO DEVELOP IN SOUTHWEST MIDDLE TN. A
FEW STORMS COULD BECOME STRONG AND POSSIBLY SEVERE...ESPECIALLY
THE ONES CURRENTLY HEADED FOR BENTON AND STEWART COUNTIES.

00Z BNA RAOB SHOWS A RATHER STEEP MID-LEVEL LAPSE RATE BUT A WEAK
WIND FIELD AND WEAK WIND SHEAR. THE STEEP MID-LEVEL LAPSE RATES
COULD STILL CONTRIBUTE TO GENERATING STRONG TO POSSIBLY SEVERE STORMS
IN ISOLATED CELLS. OF SOME CONCERN IS THE AMOUNT OF CONVECTION REFIRING
ACROSS MISSOURI BETWEEN SAINT LOUIS AND KANSAS CITY. THIS ACTIVITY
COULD MAKE A RUN TOWARD THE MID STATE LATER TONIGHT. IF THIS HAPPENS
MID-WATCH COULD GET BUSY IN A HURRY.

WILL UPDATE ZONES AROUND 9 PM TO REMOVE EVENING WORDING AND MAKE
TWEAKS BASED ON LATEST RADAR TRENDS. WILL ALSO MENTION ISOLATED
SEVERE STORMS POSSIBLE WITH DAMAGING WINDS AND LARGE HAIL BEING THE
MAIN THREAT.

THE FOLLOWING DATA WAS PROCESSED FROM THE OHX SOUNDING 00Z 04/22/05

                      BNA
STABILITY
VIL OF THE DAY        37
500 MB TEMP:         -14.1
400 MB TEMP:         -26.3

SHOWALTER-INDEX        00
TROPOPAUSE (MB)       191

JJ GEORGES K-INDEX    32

LAPSE RATE (DEGC/KM)
700 TO 500 MB         6.4

MILLERS TOTAL TOTALS  50
     VERTICAL TOTALS  28
        CROSS TOTALS  22

THICKNESSES (METERS)
1000 TO 925            681
1000 TO 850 (1300)    1405
1000 TO 700 (2840)    3010
1000 TO 500 (5400)    5646
 850 TO 700 (1540)    1605

          700MB TEMP  2.8
          700MB WIND  325/17

MEAN WIND (DEGS/KTS)
SURFACE TO  5000 FT   280/06
5000 FT TO 10000 FT   310/09

HEIGHT (KFT MSL)
-20 ISOTHERM          21.4

&&

.OHX WATCHES/WARNINGS/ADVISORIES...NONE.

&&

BOYD
01

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE NASHVILLE TN
1108 PM CDT THU APR 21 2005

TNZ005>011-022>034-056>066-075-077>080-093>095-221030-
BEDFORD-BENTON-CANNON-CHEATHAM-CLAY-COFFEE-CUMBERLAND-DAVIDSON-
DEKALB-DICKSON-FENTRESS-GILES-GRUNDY-HICKMAN-HOUSTON-HUMPHREYS-
JACKSON-LAWRENCE-LEWIS-MACON-MARSHALL-MAURY-MONTGOMERY-OVERTON-PERRY-
PICKETT-PUTNAM-ROBERTSON-RUTHERFORD-SMITH-STEWART-SUMNER-TROUSDALE-
VAN BUREN-WARREN-WAYNE-WHITE-WILLIAMSON-WILSON-
1108 PM CDT THU APR 21 2005

THIS HAZARDOUS WEATHER OUTLOOK IS FOR MIDDLE TENNESSEE.

.DAY ONE...TONIGHT...
THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS MUCH OF
MIDDLE TENNESSEE. THE AIR MASS WILL REMAIN UNSTABLE ACROSS MIDDLE
AND WESTERN TENNESSEE AND WESTERN KENTUCKY OVERNIGHT. ISOLATED SEVERE
THUNDERSTORMS ARE POSSIBLE OVERNIGHT...WITH THE PRIMARY THREAT BEING
LARGE HAIL AND DAMAGING WINDS.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY...
THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS FRIDAY.
A COLD FRONT IS EXPECTED TO MOVE INTO MIDDLE TENNESSEE FRIDAY
AFTERNOON. THUNDERSTORMS WILL DEVELOP AS THE FRONT APPROACHES...
AND A FEW STORMS COULD BECOME SEVERE WITH LARGE HAIL AND DAMAGING
WINDS FRIDAY AND FRIDAY EVENING.

A SURGE OF SHARPLY COLDER AIR WILL PUSH INTO MIDDLE TENNESSEE
DURING THE DAY SATURDAY. WELL BELOW NORMAL TEMPERATURES ARE FORECAST
FOR SATURDAY NIGHT AND EARLY SUNDAY MORNING...WITH TEMPERATURES
IN THE LOW TO MID 30S EXPECTED. PROTECTION OF OUTDOOR PLANTS FROM
POSSIBLE FROST AND COLD TEMPERATURES WILL LIKELY BE NEEDED.

.SPOTTER INFORMATION STATEMENT...
ACTIVATION OF SPOTTERS AND EMERGENCY MANAGERS MAY BE NEEDED
ON FRIDAY.

BOYD
01

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE NASHVILLE TN
919 PM CDT THU APR 21 2005

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0907 PM     HAIL             8 WSW WAYNESBORO        35.28N 87.89W
04/21/2005  0.75 INCH        WAYNE              TN   LAW ENFORCEMENT

            DIME TO PENNY SIZE HAIL

&&

31

TNZ028-063-064-220300-

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE NASHVILLE TN
937 PM CDT THU APR 21 2005

STRONG THUNDERSTORMS ARE MOVING THROUGH SOUTHEAST WILSON...NORTHERN
CANNON AND NORTHWEST DE KALB COUNTIES AT 935 PM. SMALL HAIL AND
GUSTY WINDS CAN BE EXPECTED AS THE STRONG STORMS PASS THROUGH THE
AREA.

BOYD
01

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE NASHVILLE TN
1000 PM CDT THU APR 21 2005

TNZ056-058-093-094-220400-
LAWRENCE-LEWIS-PERRY-WAYNE-
1000 PM CDT THU APR 21 2005

...STRONG THUNDERSTORMS WILL CONTINUE TO MOVE THROUGH THE SOUTHWEST
CORNER OF MIDDLE TENNESSEE...

SMALL HAIL AND DANGEROUS LIGHTNING WILL CONTINUE TO BE A HAZARD
IN AN AREA OF STRONG THUNDERSTORMS LOCATED IN THE SOUTHWEST
CORNER OF THE MID STATE.  EARLIER THIS EVENING WESTERN WAYNE COUNTY
REPORTED DIME TO PENNY SIZE HAIL ASSOCIATED WITH THESE STORMS.
NATIONAL WEATHER SERVICE RADAR INDICATES THESE STORM HAVE DECREASE
IN INTENSITY DURING THE PAST FIFTEEN MINUTES.  HOWEVER...PERSONS
IN THE PATH OF THESE STORMS SHOULD STAY ALERT FOR THREATENING WEATHER
AS THESE STORMS APPROACH THEIR AREA.

31