Severe Thunderstorm Warning 91, NWS Nashville, TN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NASHVILLE TN
215 AM CST FRI MAR 28 1997

TSTMS OVER WRN TN HAVE DEVELOPED ALONG A SECONDARY SFC THETA-E RIDGE
THAT APPEARS TO HAVE BEEN SOMEWHAT "UNDER-FORECAST" BY 00Z MODELS.
HOWEVER, THEY ARE ALSO IN AN AREA OF UPPER LVL DIFFLUENCE AND INVOF
OF FCST JET MAXIMUM. THEY ARE PROBABLY ALSO BEING ENHANCED BY
A 50H VORT AXIS THAT IS SWINGING EWD OVER WRN TN TONIGHT AND
AN 80H JET THAT IS EXPANDING INTO THE AREA. CURRENT SVR WX BOX
PROBABLY HAS THE RIGHT IDEA OF ADVANCING SVR WX POTENTIAL
TO NR THE TN RIVER BY 12Z, ALTHOUGH BLV TSTMS WILL BE IN OUR
MOST WRN COUNTIES BTWN 230 AND 4 AM. (WILL HAVE TO KEEP AN EYE OUT
NEXT SEVERAL HRS AND SEE IF WE NEED TO ROUST ANYONE OUT OF BED FOR
AN EARLY DAYSHIFT!)

DEEPEST MOISTURE AND LIFT PASS THROUGH OUR AREA THIS MORNING,
ALTHOUGH LOW LVLS SHOULD REMAIN SUFFICIENTLY MOIST TO ALLOW FOR
TSTMS LATE TDY WHEN SFC FNT MOVES IN. BLV ETA AND NGM ARE
UNREALISTIC WITH TSTM POTENTIAL AND ARE UNDER-PLAYING THE LIKELIHOOD
OF A PRE-FRONTAL SQUALL LINE DEVELOPING LATER TDY IN THE 1000-850MB
THETA-E RIDGE. WE SEEM TO LOSE THE DYNAMIC ENHACEMENT BY UPPER
JET, HOWEVER, BY LATE IN THE DAY AND ALL TSTM POTENTIAL FOCUSES
IN THE MOIST LOW LVLS AND DRY MID LVLS. ANYWAY, WOULD KEEP POPS
PRETTY HIGH UNTIL FNT PASSES THIS EVENING.

FAN AND FWC FCST TEMPS ARE RATHER AGREEABLE AND PROBABLY WOULDN'T
VEER TOO FAR EITHER SIDE.

OVERALL, FCST SHOULD REQUIRE ONLY MINOR CHANGES.

BNA 75/51/66/42 8200