DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1127 AM CST THU DEC 30 2010
VALID 311200Z - 011200Z
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE OZARKS/SRN MO TO E
TX/LOWER MS VALLEY...
...SYNOPSIS...
LATEST MODELS REMAIN CONSISTENT SHOWING THE DAY 1 DEEPENING WRN
LONGWAVE TROUGH MOVING ENEWD INTO THE CENTRAL CONUS ON FRIDAY/NEW
YEARS EVE. STRONGEST FORCING ALOFT/GREATEST HEIGHT FALLS ARE
EXPECTED TO SPREAD NEWD ACROSS NRN OK AND THE CENTRAL PLAINS TO THE
UPPER MIDWEST/WRN GREAT LAKES ATTENDANT TO THE NEWD MOVEMENT OF A
LEAD CLOSED LOW/SHORTWAVE TROUGH. SURFACE LOW WITH THIS LEAD SYSTEM
WILL TRACK FROM SRN KS FRIDAY MORNING AND REACH THE UPPER MS VALLEY
FRIDAY EVENING/NIGHT. A TRAILING COLD FRONT AND PRE- FRONTAL TROUGH
SPREADING EWD ACROSS THE SLIGHT RISK AREA TOWARD THE MID/LOWER MS
VALLEY REGION LATE IN PERIOD ARE EXPECTED TO BE THE PRIMARY FOCI FOR
TSTM DEVELOPMENT/SVR THREAT DURING DAY 2.
...OZARKS/ARKLATEX/E TX TO MIDDLE/LOWER MS VALLEY...
DESPITE WEAKER INSTABILITY EXPECTED ACROSS THE OZARKS INTO SRN/
CENTRAL MO...CLOSER PROXIMITY OF THIS REGION TO THE BRUNT OF GREATER
HEIGHT FALLS AND STRONG SWLY LOW LEVEL JET /40-50 KT/ SUGGESTS A
POTENTIAL FOR DAMAGING WINDS TO PERSIST FROM THE END OF DAY 1 INTO
DAY 2. THIS THREAT SHOULD GENERALLY BE CONFINED TO THE PRE-FRONTAL
TROUGH AS IT SPREADS EWD ACROSS THE NRN EXTENT OF THE SLIGHT RISK
AREA...WITH FORECAST SOUNDINGS ALSO INDICATING A POTENTIAL FOR AN
ISOLATED TORNADO GIVEN THE STRENGTH OF THE LLJ AND LOW LEVEL SHEAR.
THE SRN EXTENT OF THE SLIGHT RISK HAS BEEN EXPANDED ACROSS E TX AND
TO THE LA COAST. A HIGHER THETAE AIR MASS...FORCING FOR ASCENT
ATTENDANT TO MID AND UPPER LEVEL JET STREAKS APPROACHING FROM
MEXICO...AND THE LOW LEVEL WAA SUGGEST A GREATER LIKELIHOOD FOR
SURFACE BASED TSTMS FARTHER S THAN PREVIOUSLY FORECAST. SLY LOW
LEVEL FLOW WILL RESULT IN SURFACE DEWPOINTS IN THE MID 60S BECOMING
ESTABLISHED ACROSS SE TX...MUCH OF LA AND SWRN MS ON FRIDAY. THIS
COMBINED WITH SOME SURFACE HEATING AND MIDLEVEL LAPSE RATES CLOSE TO
7 C/KM SHOULD RESULT IN MLCAPE EXCEEDING 1000 J/KG. HEIGHT FALLS
WILL BE NEUTRAL TO VERY WEAK /10-20 METERS PER 12 HR AT 500 MB/ FROM
E TX INTO LOWER MS VALLEY THIS PERIOD. HOWEVER...THE AFOREMENTIONED
DEEP LAYER FORCING AND CONVERGENCE ALONG A PRE-FRONTAL
TROUGH/CONFLUENCE ZONE SUGGEST A SECOND AREA OF GREATER STORM
COVERAGE IS POSSIBLE FROM E TX INTO LOWER MS VALLEY. DEGREE OF
DESTABILIZATION COMBINED WITH EFFECTIVE BULK SHEAR /40-50 KT/ AND
0-1 KM SRH AROUND 200 M2/S2 WILL SUPPORT MULTI-MODAL POTENTIAL FOR
SEMI-DISCRETE/EMBEDDED SUPERCELLS AND QLCS DEVELOPMENT...WITH
POSSIBILITIES FOR DAMAGING WINDS/SOME TORNADOES...AND SOME SEVERE
HAIL.
..PETERS.. 12/30/2010
