SWOD48
SPC AC 170856
DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0256 AM CST SAT DEC 17 2011
VALID 201200Z - 251200Z
...DISCUSSION...
COMPLEX SPLIT UPPER PATTERN WILL LIKELY PERSIST INTO MUCH OF THE 4-8
PERIOD WITH A SERIES OF UPPER LOWS DROPPING INTO THE SWRN STATES
BEFORE EJECTING EWD AND REJOINING NRN STREAM. DETERMINISTIC MODELS
AND ENSEMBLE MEMBERS APPEAR IN REASONABLE AGREEMENT INTO DAY 4...BUT
BECOME INCREASINGLY DISPERSIVE BEYOND THIS TIME.
DAYS 4-5...UPPER TROUGH THAT WILL LIKELY BE OVER THE SRN PLAINS
EARLY DAY 4 WILL CONTINUE ENEWD INTO THE LOWER MS VALLEY TUESDAY AND
EVENTUALLY INTO THE TN/OH VALLEYS TUESDAY NIGHT INTO WEDNESDAY.
HOWEVER...MODELS DIFFER ON SPEED AND RATE OF DEAMPLIFICATION OF THIS
FEATURE. IN EITHER CASE...AXIS OF PARTIALLY MODIFIED GULF AIR WILL
ADVECT INTO PRE-FRONTAL WARM SECTOR ALONG STRONG SLY LLJ WITH
DEWPOINTS IN THE 50S TO LOW 60S LIKELY INTO PORTIONS OF GULF COAST
STATES. THIS WILL CONTRIBUTE TO DESTABILIZATION...BUT INSTABILITY
WILL REMAIN LIMITED BY WIDESPREAD CLOUDS AND POOR LAPSE RATES. WHILE
STRONG VERTICAL SHEAR WILL CONTRIBUTE TO A THREAT OF SEVERE STORMS
ALONG AND AHEAD OF THE ATTENDANT COLD FRONT...LIKELIHOOD OF A
MARGINAL THERMODYNAMIC ENVIRONMENT LOWERS CONFIDENCE IN A 30% SEVERE
COVERAGE AREA AT THIS TIME.
..DIAL.. 12/17/2011
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