[SWODY2] SWODY2

[Severe Weather Outlook - Day 2]

ACUS02 KWNS 160550
SWODY2
SPC AC 160549

DAY 2 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
1249 AM CDT FRI JUN 16 2006

VALID 171200Z - 181200Z

...THERE IS A SLGT RISK OF SVR TSTMS SAT/SAT NIGHT ACROSS PARTS OF
THE CNTRL/SRN PLAINS....

MODELS INDICATE THAT A TRANSITION TOWARD A LESS AMPLIFIED UPPER FLOW
REGIME WILL BEGIN DURING THIS FORECAST PERIOD...WITH STRONGER
WESTERLIES GRADUALLY DEVELOPING NORTHWARD THROUGH THE NORTHWESTERN/
NORTH CENTRAL U.S. INTO SOUTHEASTERN CANADA.  WITHIN THIS REGIME...A
CLOSED LOW WILL ACCELERATE EASTWARD ALONG THE CENTRAL CANADIAN/U.S.
BORDER TODAY...IN RESPONSE TO A RAPIDLY APPROACHING UPSTREAM SHORT
WAVE TROUGH.  A SIGNIFICANT IMPULSE EMBEDDED WITHIN THE BROADER
SCALE CIRCULATION IS PROGGED TO LIFT AWAY FROM THE INTERNATIONAL
BORDER TOWARD HUDSON/JAMES BAY EARLY SATURDAY. HOWEVER...MODELS
SUGGEST REMNANTS OF CLOSED LOW AND UPSTREAM IMPULSE WILL CONSOLIDATE
INTO ANOTHER BROADER SCALE TROUGH...WHICH WILL CONTINUE EASTWARD
TOWARD CONFLUENT REGIME OVER THE UPPER GREAT LAKES REGION LATER
SATURDAY INTO EARLY SUNDAY.

FARTHER SOUTH...MID-LEVEL HEIGHT RISES ARE PROGGED THROUGH MUCH OF
THE CENTRAL/SOUTHERN TIER OF THE U.S...AS SUBTROPICAL RIDGING BEGINS
TO DEVELOP NORTHWARD.  A SHORT WAVE TROUGH WILL PROGRESS EAST OF THE
SOUTHERN ROCKIES THROUGH MUCH OF THE SOUTHERN PLAINS BY LATE
SATURDAY/EARLY SUNDAY. THIS SYSTEM WILL WEAKEN BETWEEN UPPER HIGH
CENTERS DEVELOPING INTO THE EASTERN AND SOUTHWESTERN STATES. 
HOWEVER...FORCING ASSOCIATED WITH THIS FEATURE...AND REMNANTS OF A
DOWNSTREAM WAVE SLOWLY LIFTING OUT OF THE WESTERN GULF COAST
REGION...ARE EXPECTED TO CONTRIBUTED TO CONSIDERABLE CONVECTIVE
DEVELOPMENT OVER A BROAD AREA OF THE CENTRAL U.S. DURING THIS
FORECAST PERIOD.  THE MOST VIGOROUS THUNDERSTORMS ARE EXPECTED TO
GENERALLY BE FOCUSED NEAR A LEE SURFACE TROUGH ACROSS PARTS OF THE
CENTRAL/SOUTHERN PLAINS. 

...CENTRAL/SOUTHERN PLAINS...
VARIABILITY EXISTS AMONG THE MODELS CONCERNING THE TRACK OF THE
MID-LEVEL COLD CORE...BUT A LARGE CONVECTIVE CLUSTER COULD BE
ONGOING EARLY SATURDAY IN ASSOCIATION WITH THIS FEATURE ACROSS THE
CENTRAL/SOUTHERN HIGH PLAINS.  THIS SEEMS MOST LIKELY ACROSS PARTS
OF CENTRAL KANSAS/WESTERN OKLAHOMA INTO NORTHWEST TEXAS. 
ALONG/AHEAD OF ASSOCIATED SURFACE COLD POOL...AND SOUTHWARD ALONG
SURFACE TROUGH/DRY LINE THROUGH WESTERN TEXAS...LAPSE RATES SHOULD
BECOME QUITE STEEP IN CONJUNCTION WITH DIFFERENTIAL THERMAL
ADVECTION AND DAYTIME HEATING. THIS WILL SUPPORT MODERATE TO STRONG
INSTABILITY BY LATE AFTERNOON...WITH MIXED LAYER CAPE PEAKING IN THE
2000 TO 4000 J/KG RANGE.  

DESTABILIZATION AND LARGE-SCALE FORCING ARE EXPECTED TO GENERATE
SUBSTANTIAL VIGOROUS LATE AFTERNOON/EVENING THUNDERSTORMS...WITHIN A
THERMODYNAMIC ENVIRONMENT FAVORABLE FOR DAMAGING DOWNBURSTS AND
LARGE HAIL.  BEFORE INSTABILITY WANES WITH LOSS OF DAYTIME HEATING
...ACTIVITY FROM PARTS OF CENTRAL/SOUTHERN OKLAHOMA INTO WEST
CENTRAL TEXAS COULD BE AUGMENTED BY MODERATELY STRONG SHEAR...AS A
SOUTHERLY LOW-LEVEL JET STRENGTHENS DURING THE EVENING BENEATH
WESTERLY MID-LEVEL FLOW.

...UPPER MISSISSIPPI VALLEY/GREAT LAKES REGION...
INSTABILITY IS MORE UNCERTAIN ACROSS THIS AREA DUE TO THE LIKELIHOOD
OF WEAKER LAPSE RATES. COLDER MID-LEVEL AIR MASS IS PROGGED TO LAG
TO THE WEST OF A PRE-FRONTAL LOW-LEVEL CONFLUENT BAND...WHICH IS
EXPECTED TO BECOME THE FOCUS FOR THE PRIMARY THUNDERSTORM ACTIVITY
FROM PARTS OF NORTHEAST IOWA/SOUTHWEST MINNESOTA THROUGH CENTRAL
WISCONSIN/UPPER MICHIGAN LATE SATURDAY AFTERNOON AND EVENING. 
SURFACE HEATING IN THE VICINITY OF THIS FEATURE MAY ALSO BE
RESTRICTED BY CONSIDERABLE CLOUD COVER.  HOWEVER...MODERATELY STRONG
/30-35+ KT/ SOUTHWESTERLY MEAN FLOW REGIME WILL ENHANCE STORM
MOTIONS AND POTENTIAL FOR GUSTY WINDS...WHICH COULD BRIEFLY APPROACH
OR EXCEED SEVERE LIMITS.

..KERR.. 06/16/2006