Flash Flood Warning 17, NWS Nashville, TN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NASHVILLE TN
225 PM CST SUN MAR 17 2002

FORECAST QUANDARIES...FLOOD WATCH EXTENSION

CURRENT ASOS/AWOS OBS AND REGIONAL SAT/RADAR MOSIAC IMAGERY SHOWING
TRAINING SHWRS/TS FROM JAMESTOWN...TO BNA...TO N OF MEM..TO LIT...TO
N OF SHV...AND STARTING TO MOVE NWD. TEMPS/DEWPOINTS IN THE MID 50S
TO MID 60S...WITH SWLY SFC WINDS. WARM FRONT MOVING INTO N INTO E KY...
WITH COLD FRONT STRECHING FROM BNA...TO JUST W OF MEM. ALOFT...PROGRESSIVE
SWLY FLOW.

12Z SUN REGIONAL MODEL EVOLUTIONS ARE GENERALLY SIMILAR THRU 12Z WED...
ESPECIALLY IN THE UPPER LEVELS. AVN MODEL VERIFYING BEST AS OF LATE...
AND CONTINUES TO LOOK AS THE MOST REASONABLE SOLUTION. THUS...WILL
LEAN ACCORDINGLY.

SFC FRONTAL SYSTEM SHOULD SLOWLY MOVE TO E REMAINDER OF THIS AFTERNOON
AND MOVE INTO E TN...WITH WEAK HIGH PRESSURE BUILDING IN BEHIND. HOWEVER...
WITH THIS PRONOUNCED OF AN OVERRUNNING EVENT...EFFECTS FROM WEAK HIGH
PRESSURE WILL BE NON SIGNIFICANT. FRONT THEN SHOULD SAG SEWD INTO N MS
..N AL...AND SE E TN...WITH ANOTHER FRONT APPROACHING  MID STATE FROM
THE MS-OHIO VALLEYS AND BE POSITIONED NEAR THE LAND BETWEEN THE LAKES
REGION BY 12Z MON. FRONT TO WILL BECOME A WARM FRONT...AS WELL A FRONT
TO OUR N...AS IT DRIFTS N.

BEST INSTABILITY WILL REMAIN TO OUR SE THRU 12Z MON...THEN REDEVELOP
ACROSS MID STATE BY 00Z TUE...AND BECOMING EVEN MORE PRONOUNCED
AFTER 12Z TUE.  LOOK FOR MOST CONVECTION TO BE ELEVATED IN NATURE.
CAN NOT RULE OUT ISOLATED SVR TS DEVELOPMENT THRU PERIOD...BUT WITH
LITTLE CAPE AND WET-BULB/FREEZING LEVEL HEIGHTS RELATIVELY HIGH...
HAIL PRODUCTION WOULD BE LIMITED...STRONG DAMAGING WINDS WOULD BE
THE MAJOR CONCERN. BELIEVE BEST CHANCE FOR SVR WOULD BE ON TUE...AS
MENTIONED IN DAY THREE CONVECTIVE OUTLOOK. WILL NOT MENTION SVR IN
ZONES.

MAIN FORECAST QUANDARY CENTERS AROUND EXTENSION OF FLOOD WATCH TONIGHT...
AND EVEN INTO MON. HPC PROGGING A 2 INCH BULLS-EYE ACROSS E PORTIONS
OF MID STATE...WITH W PORTIONS 1-1.5 INCHES...AND KEEPING THIS PATTERN
IN TACT THRU 00Z TUE...ALTHOUGH SOME WEAKENING IS EXPECTED BY THE
AVN SOLUTION. 1 INCH MAX EXPECTED ACROSS MID STATE BY 00Z WED.
AVN MOCKS THIS NICELY AS SWLY FLOW CONTINUES UNTIL UPPER LEVEL LOW
PASSAGE AFTER 12Z WED.

AVN SHOWING BEST SWLY LOW LEVEL JET DYNAMICS ON TUE...BUT 30-40KTS EXPECTED
THRU MAJORITY OF PERIOD. MID TO UPPER LEVEL SWLY JET DYNAMICS WILL BE STRONG
THRU MAJORITY OF PERIOD ALSO...MOVING QUICKLY ANY DISTURBANCES ALOFT.

WITH ALL THIS IN MIND...WILL GO WITH CAT POPS TONIGHT AND THRU MON
MORNING ACROSS ENTIRE CWA. CONVECTION MAY BE MORE IN THE LIKELY CAT
MON AFTERNOON BEFORE REDEVELOPING AFTER 00Z TUE. THUS...WILL EXTEND
WATCH THRU 00Z TUE. WILL GO WITH LIKELY POPS THRU WED MORNING.
WILL MENTION SCATTERED TS THRU TUE. WITH BEST CHANCE OF TS AFTER 12Z
TUE...WILL GO NUMEROUS THRU WED MORNING.

REST OF WEEK...FRONT WILL HAVE PUSHED INTO APPALACHIANS BY 12Z WED...
WITH HIGH PRESSURE SYSTEM BUILDING IN FROM CNTRL ROCKIES. HIGH PRESSURE
WILL DOMINATE REGION/S WX PATTERN THRU REMAINDER OF THE PERIOD...
PROVIDING FOR PTCDLY SKIES. A WEAK FRONTAL PASSAGE WILL OCCUR ON FRI.
MORNING...POSSIBLY BRINGING SOME ADDITIONAL CLOUDINESS...BUT AT THIS
TIME WILL NOT MENTION AND LEAVE TO LATER SOLUTIONS.

TEMPS...WILL GO CLOSE TO AVN SOLUTION ON TEMPS...EXCEPT FOR MON WHERE
FAN AND ETA IN HOUSE BOUNDARY TEMP SCHEME VALUES MORE APPROPRIATE.

THANKS FOR COORDINATION MEM...JKL...BHM...MRX...SDF

PRELIMINARY NUMBERS FOR COORDINATION PURPOSES ONLY...

BNA WT 054/065/053/072 9876
CSV WT 052/063/050/068 9876

.BNA...FLOOD WATCH IN EFFECT UNTIL 00Z TUE.
14
JBW