SWODY2
SPC AC 060547
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1147 PM CST SAT JAN 05 2008
VALID 071200Z - 081200Z
..THERE IS A SLGT RISK OF SVR TSTMS FROM THE MID MS VALLEY SWD INTO
THE ARKLATEX...
..SYNOPSIS...
PROGRESSIVE LARGE-SCALE PATTERN WILL EXIST THROUGH THE DAY TWO
PERIOD WITH PRIMARY FEATURE OF INTEREST BEING MIDLEVEL TROUGH WHICH
WILL TRANSLATE FROM THE INTERMOUNTAIN W EWD INTO THE CNTRL PART OF
THE NATION. SEVERAL SMALLER-SCALE PERTURBATIONS ARE FORECAST TO BE
EMBEDDED WITHIN BROADER AIR FLOW PATTERN ATTENDANT TO THIS
TROUGH...THE MOST NOTABLE OF WHICH ARE: 1) VORTICITY MAXIMUM WHICH
WILL LIFT NEWD FROM THE CNTRL HIGH PLAINS INTO THE UPPER MS
VALLEY...AND 2) JET STREAK/VORTICITY MAXIMUM WHICH WILL SHIFT NEWD
FROM THE SRN ROCKIES INTO THE OZARK PLATEAU REGION BY MONDAY NIGHT.
IN THE LOW LEVELS...THE TRACK OF PRIMARY SURFACE LOW WILL BE
COINCIDENT WITH FORMER IMPULSE MENTIONED ABOVE...DEVELOPING NEWD
FROM WRN KS INTO THE LOWER MO VALLEY BY MONDAY EVENING AND
EVENTUALLY INTO THE UPPER GREAT LAKES BY TUESDAY MORNING.
ASSOCIATED WARM FRONT WILL LIFT NWD THROUGH THE UPPER MIDWEST AND
GREAT LAKES REGION WHILE TRAILING COLD FRONT PUSHES EWD/SEWD THROUGH
THE CNTRL PLAINS INTO MID MS VALLEY...AND MORE SWD INTO THE SRN
PLAINS.
..MID MS VALLEY SWD INTO THE ARKLATEX...
06/00Z UPPER-AIR OBSERVATIONS OVER THE TX COAST INTO LOWER MS VALLEY
INDICATE THAT A MODIFIED GULF AIR MASS /SURFACE DEWPOINTS IN THE
UPPER 50S TO LOWER 60S AND LOWEST MEAN MIXING RATIOS OF 9-11 G PER
KG/ HAS ALREADY BECOME ESTABLISHED ONSHORE. PERSISTENT...SLY/SWLY
LOW-LEVEL FLOW WILL SUPPORT THE CONTINUED ADVECTION OF THIS AIR MASS
NWD THROUGH THE MS RIVER VALLEY WITH DEWPOINTS INCREASING INTO THE
50S MONDAY INTO PARTS OF IL/IND AND LOWER 60S AS FAR N AS THE MO
BOOTHEEL. THE STEEPEST MIDLEVEL LAPSE RATES WILL REMAIN LARGELY
DISPLACED TO THE N/NW OF THIS LOW-LEVEL MOISTURE AXIS WITH AIR MASS
EXPECTED TO BECOME ONLY MARGINALLY UNSTABLE WITH MLCAPES OF LESS
THAN 1000 J/KG.
CLUSTERS OF ELEVATED TSTMS MAY BE ONGOING MONDAY MORNING OR DEVELOP
EARLY IN THE DAY INVOF RETREATING WARM FRONT OVER PORTIONS OF
IL/SERN WI INTO LOWER MI AS WAA AND ISENTROPIC ASCENT INCREASE ALONG
AND N OF BOUNDARY. ELEVATED INSTABILITY IS EXPECTED TO REMAIN QUITE
MARGINAL AND NO SEVERE STORMS ARE ANTICIPATED.
POTENTIALLY MORE ORGANIZED STORM DEVELOPMENT IS EXPECTED TO OCCUR
LATER MONDAY AFTERNOON INTO MONDAY NIGHT FROM THE OZARK PLATEAU SWD
INTO THE ARKLATEX AS FORCING FOR ASCENT ASSOCIATED WITH
APPROACHING...MIDLEVEL JET STREAK BEGINS TO OVERSPREAD WRN EDGE OF
PRIMARY INSTABILITY AXIS. LATEST SHORT TERM GUIDANCE INDICATES THAT
THE MAJORITY OF THESE STORMS WILL LIKELY INITIATE TO THE E OF
SURFACE COLD FRONT...ALONG A LOW-LEVEL CONFLUENCE ZONE OR
PRE-FRONTAL TROUGH.
FORECAST SOUNDINGS SUGGEST THAT STORMS DEVELOPING OVER NRN PORTIONS
OF SLIGHT RISK AREA /I.E. CNTRL MO INTO W-CNTRL IL/ MAY REMAIN
SLIGHTLY ELEVATED ABOVE A STABLE NEAR SURFACE LAYER WITH LARGE HAIL
BEING THE PRIMARY SEVERE THREAT. FARTHER S FROM SRN MO INTO THE
ARKLATEX...STORMS SHOULD BE SURFACE-BASED WITHIN A KINEMATIC
ENVIRONMENT CHARACTERIZED BY RELATIVELY STRONG LOW AND DEEP LAYER
SHEAR. AS SUCH...POTENTIAL WILL EXIST FOR SUPERCELLS CAPABLE OF
DAMAGING WINDS AND PERHAPS A FEW TORNADOES. THIS SEVERE THREAT
SHOULD CONTINUE OVERNIGHT EWD TOWARD THE MS RIVER AS STORMS GROW
UPSCALE INTO ONE OR MULTIPLE LINES.
.MEAD.. 01/06/2008
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