Severe Thunderstorm Warning 221, NWS Nashville, TN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NASHVILLE TN
130 AM CDT WED AUG 22 2001

CURRENTLY, VERY LITTLE OCCURRING ACROSS THE MID STATE, DESPITE A
HUMID AND UNSTABLE ENVIRONMENT. SURFACE BOUNDARY REMAINS NORTH OF THE
OHIO RIVER, WHERE CONVECTION IS JUST BEGINNING TO FIRE.

MODELS ARE IN A BIT OF DISARRAY THIS CYCLE, WITH ETA MOST AGGRESSIVE,
AND AVN/NGM SOMEWHAT WEAKER. FRONTAL MOVEMENT THE NEXT 24-48 HOURS
PRESENTS THE GREATEST QUANDARY, BUT DO EXPECT THE BOUNDARY TO SAG
SOUTHWARD INTO MIDDLE TENNESSEE BY TOMORROW. ALTHOUGH THE ASSOCIATED
CLOUDINESS WILL TEMPER AFTERNOON TEMPERATURES, EXPECT LITTLE CHANGE
IN AIR MASS CHARACTERISTICS UNTIL SUNDAY OR MONDAY, WHEN NEXT COLD
FRONT IS EXPECTED TO PASS.

ANYWAY, SCATTERED CONVECTION IS EXPECTED TO DEVELOP ACROSS NORTHERN
MIDDLE TENNESSEE LATER TONIGHT. MOST RECENT 24HR PRECIPITATION
FORECAST FROM HPC GIVES GREATEST AMOUNTS (0.25 TO 0.50) ACROSS OUR
NORTH THROUGH 12Z TOMORROW, WITH MUCH LIGHTER AMOUNTS ACROSS THE
SOUTH. STILL, BELIEVE SOME AREAS NEAR THE KY BORDER COULD SEE HEAVY
RAINFALL TONIGHT. WILL BREAK OFF A SEPARATE GROUP FOR THESE NORTHERN
COUNTIES AND GO LIKELY THERE.

WITH MODEL SOUNDINGS SHOWING MOIST AND UNSTABLE ENVIRONMENT REMAINING
IN PLACE THE NEXT 3 DAYS OR SO, WILL LEAVE IN SCATTERED AFTERNOON AND
EVENING CONVECTION THROUGH SUNDAY, BEFORE COLD FRONT IS FORECAST TO
MOVE ACROSS THE REGION LATE SUNDAY OR EARLY MONDAY, USHERING IN
COOLER AND DRIER AIR.

BNA 72/89/70/88/69 54333
CSV 66/84/64/83/63 54333

.BNA...NONE.

08

TNZ005>011-022>034-056>066-075>080-093>097-241030-

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE NASHVILLE TN
230 PM CDT THU AUG 23 2001

...THUNDERSTORMS WITH POTENTIALLY HEAVY RAINFALL AND DAMAGING WINDS
ARE POSSIBLE OVERNIGHT ACROSS NORTHERN MIDDLE TENNESSEE...

A SURFACE FRONT CURRENTLY LOCATED ALONG THE OHIO VALLEY WILL CONTINUE
TO MOVE SOUTHWARD, AND INTO THE MID STATE DURING THE NEXT 24 HOURS.
WITH THE FRONT MOVING INTO MORE HUMID AND UNSTABLE AIR, THE CHANCE
FOR SHOWERS AND THUNDERSTORMS WILL INCREASE.

THESE THUNDERSTORMS WILL HAVE THE POTENTIAL TO PRODUCE HEAVY RAINFALL
IN SOME AREAS. THE BEST CHANCE FOR HEAVY RAINFALL WILL BE ACROSS THE
NORTHERN COUNTIES OF MIDDLE TENNESSEE AND THE CUMBERLAND PLATEAU,
PRIMARILY NORTH OF INTERSTATE 40. THESE AREAS CAN GENERALLY EXPECT
BETWEEN ONE QUARTER AND ONE HALF INCH OF RAINFALL BY FRIDAY MORNING,
ALTHOUGH ISOLATED AMOUNTS OF AN INCH OR MORE ARE POSSIBLE.

A SECOND THREAT FROM THE THUNDERSTORMS WILL BE FOR DAMAGING DOWNBURST
WINDS. ALTHOUGH WIDESPREAD SEVERE WEATHER IS NOT FORECAST, ISOLATED
EVENTS OF SEVERE THUNDERSTORM WINDS ARE QUITE POSSIBLE.

MEANWHILE, AREAS ALONG AND NEAR THE ALABAMA STATE LINE WILL HAVE THE
LEAST CHANCE OF GETTING RAIN OVERNIGHT.

ACTIVATION OF EMERGENCY MANAGERS AND SPOTTER GROUPS MAY BE NEEDED
TONIGHT, PRIMARILY FOR LOCALLY HEAVY RAINFALL AND STRONG DAMAGING
WINDS ACROSS THE NORTHERN COUNTIES OF MIDDLE TENNESSEE.

08