[SWODY2] SWODY2

[Severe Weather Outlook - Day 2]

ACUS02 KWNS 111720
SWODY2
SPC AC 111718

DAY 2 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
1118 AM CST MON DEC 11 2006

VALID 121200Z - 131200Z

...NO SVR TSTM AREAS FORECAST...

A COMPLEX SPLIT UPPER FLOW PATTERN PERSISTS ACROSS MUCH OF NORTH
AMERICA.  WITHIN THIS REGIME...AN AMPLIFIED TROUGH...WHICH DEVELOPED
OVER THE WEEKEND IN ONE STRONGER BELT ACROSS CALIFORNIA INTO THE
SOUTH CENTRAL STATES...CONTINUES TO SHIFT EAST OF THE ROCKIES INTO
THE CENTRAL/SOUTHERN PLAINS.  MODELS INDICATE THAT THIS LARGER SCALE
FEATURE WILL LIFT NORTHEASTWARD TOWARD THE MISSISSIPPI VALLEY BY 12Z
TUESDAY...BEFORE PROGRESSING INTO/THROUGH THE GREAT LAKES/OHIO
VALLEY REGION BY 12Z WEDNESDAY.  THIS IS PROGGED TO OCCUR AS A
STRONG HIGH-LEVEL JET STREAK NOSES INTO THE CANADIAN
ROCKIES/NORTHERN U.S. INTERMOUNTAIN REGION...IN A STREAM EMANATING
FROM THE WESTERN/CENTRAL PACIFIC.

ASSOCIATED WITH THE SOUTHERN BRANCH TROUGH...MODELS CONTINUE TO
INDICATE THAT LEE SURFACE CYCLOGENESIS WILL REMAIN WEAK.  THIS WILL
TEND TO MINIMIZE CONVECTIVE POTENTIAL ALONG/AHEAD OF ASSOCIATED
SURFACE FRONT AS IT ADVANCES THROUGH THE CENTRAL U.S. EARLY THIS
WEEK.  ALSO...IN THE WAKE OF A SERIES OF SIGNIFICANT COLD
INTRUSIONS... THE BOUNDARY LAYER OVER THE GULF OF MEXICO IS STILL IN
THE PROCESS OF MODIFYING.  BUT...A WEAK RETURN FLOW OF
MOISTURE...CHARACTERIZED BY MID/UPPER 50S DEW POINTS...IS ONGOING
FROM THE WESTERN GULF OF MEXICO INTO THE SOUTHEASTERN PLAINS.

...MIDDLE MISSISSIPPI VALLEY...
VARIABILITY EXISTS AMONG THE MODELS CONCERNING THE DETAILS...BUT AN
IMPULSE IS GENERALLY FORECAST TO PROGRESS THROUGH THE BASE OF THE
LARGER SCALE TROUGH AS IT LIFTS INTO/THROUGH THE MISSISSIPPI VALLEY
LATER TODAY INTO TUESDAY.  THIS IS PROGGED TO CONTRIBUTE TO A
STRENGTHENING SOUTHWESTERLY MID-LEVEL JET STREAK ACROSS THE MIDDLE
MISSISSIPPI VALLEY BY TUESDAY AFTERNOON...WITH STRONGER MID-LEVEL
COOLING ADVANCING NORTHEAST OF THE OZARK PLATEAU INTO THE LOWER OHIO
VALLEY.  THIS MAY BE PRECEDED BY AT LEAST WEAK SURFACE HEATING IN A
DRY SLOT NOSING THROUGH THE MIDDLE MISSISSIPPI VALLEY...IN THE WAKE
OF EARLY DAY PRE-FRONTAL WARM ADVECTION CONVECTION...WHICH WILL BE
POSSIBLE IN A BAND THROUGH MUCH OF THE MISSISSIPPI VALLEY.

MODEL FORECAST SOUNDINGS ACROSS PARTS OF EASTERN ARKANSAS AND
SOUTHEAST MISSOURI...INTO CENTRAL/SOUTHERN ILLINOIS AND WESTERN
KENTUCKY/TENNESSEE...INDICATE MIXED LAYER CAPE OF AROUND 500 J/KG
DEVELOPING BY 20-21Z TUESDAY.  THIS IS RATHER WEAK...BUT PROFILES
ARE SUGGESTIVE OF SUFFICIENT CONVECTIVE INSTABILITY TO SUPPORT AT
LEAST A LOW RISK OF MARGINALLY SEVERE HAIL/WIND GUSTS IN ANY STORMS
DEVELOPING IN FAVORABLY SHEARED DEEP LAYER FLOW.  AND... INHIBITION
APPEARS LIKELY TO BECOME SUFFICIENTLY WEAK FOR A BROKEN LINE OF
STORMS TO DEVELOP IN RESPONSE TO FRONTAL FORCING ADVANCING EAST OF
THE MIDDLE MISSISSIPPI VALLEY BY EARLY TUESDAY EVENING.  LIMITED
SEVERE THREAT WILL PROBABLY DIMINISH AS THIS FORCING SHIFTS EASTWARD
INTO COOLER AND MORE STABLE/STABILIZING BOUNDARY LAYER.

..KERR.. 12/11/2006