[SWODY1] SWODY1

[Severe Weather Outlook Day 1]

ACUS01 KWNS 050528
SWODY1
SPC AC 050527

DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
1227 AM CDT SAT AUG 05 2006

VALID 051200Z - 061200Z

...THERE IS A MDT RISK OF SVR TSTMS FROM ERN NORTH DAKOTA AND NERN
SOUTH DAKOTA ACROSS MUCH OF MINNESOTA...

...THERE IS A SLGT RISK OF SVR TSTMS SURROUNDING THE MDT RISK AREA
FROM THE CNTRL DAKOTAS AND NRN NEB...EAST ACROSS NRN IA AND THE
UPPER MS VALLEY/WRN GREAT LAKES...

...THERE IS A SLGT RISK OF SVR TSTMS OVER THE NORTHEAST GULF COAST
AND PARTS OF THE SOUTHEAST...

...WIDESPREAD SEVERE THUNDERSTORMS WITH DAMAGING WINDS AND LARGE
HAIL ARE EXPECTED TO DEVELOP EAST ACROSS PARTS OF THE DAKOTAS AND
MINNESOTA THIS AFTERNOON AND TONIGHT...

...SYNOPSIS...
BROAD MID-UPPER LEVEL SUBTROPICAL RIDGE AXIS WILL REMAIN SITUATED
ACROSS THE SCNTRL U.S. FROM THE FOUR CORNERS REGION EWD TO THE MID
ATLANTIC AND SOUTHEAST. BELT OF ZONAL NRN STREAM FLOW WILL CONTAIN A
POTENT...PROGRESSIVE...AND COMPACT SHORT WAVE DISTURBANCE WHICH WILL
TRANSLATE EWD FROM NERN MT TO SRN ONTARIO AND THE UPPER MS VALLEY
DURING THE PERIOD. WHILE ASSOCIATED SURFACE CYCLOGENESIS WITH THIS
NRN STREAM IMPULSE WILL OCCUR OVER THE CANADIAN PRAIRIES THROUGH THE
DAY TODAY...MODEST HEIGHT FALLS AND INCREASINGLY DIFFLUENT FLOW ON
THE NOSE 0F 50-70 KT MID LEVEL JET WILL SPREAD EAST ATOP STRONGLY
UNSTABLE WARM SECTOR FROM THE ERN DAKOTAS TO MN. SEVERE STORMS ARE
EXPECTED TO FORM AHEAD OF ASSOCIATED COLD FRONT WHICH WILL SWEEP
ESEWD ACROSS THE NRN PLAINS TO THE WRN GREAT LAKES REGION FROM LATE
THIS AFTERNOON THROUGH EARLY SUNDAY.

...NRN PLAINS TO UPPER MS VALLEY...
INGREDIENTS APPEAR TO BE COMING TOGETHER FOR POTENTIALLY SIGNIFICANT
SEVERE WEATHER EPISODE ACROSS ERN ND...NERN SD...AND MN LATER THIS
AFTERNOON AND TONIGHT. A LEADING LOW-AMPLITUDE SHORT WAVE TROUGH AND
MODEST LOW LEVEL JET DIRECTED INTO MN WERE AIDING LOW LEVEL MOISTURE
RETURN AND MAINTAINING WEAK CONVECTIVE ACTIVITY ACROSS THE AREA
ATTM. EARLY ELEVATED CONVECTION IS EXPECTED TO DISSIPATE RAPIDLY
AFTER SUNRISE AS LOW LEVEL FLOW FIELDS ADJUST TO INFLUENCE OF
STRONGER UPSTREAM IMPULSE MOVING ESEWD FROM NERN MT.

INTENSE SURFACE HEATING BENEATH PRONOUNCED ELEVATED MIXED LAYER AND
ADIABATIC COOLING ALOFT ASSOCIATED WITH THE APPROACHING TROUGH WILL
LEAD TO THE DEVELOPMENT OF STRONG INSTABILITY AHEAD OF DRYLINE/COLD
FRONT BY AFTERNOON. MLCAPE ACROSS THE CNTRL/ERN DAKOTAS SHOULD
EASILY CLIMB TO 2000 J/KG WITH INITIALLY STRONG CAPPING ALLOWING LOW
LEVEL MOISTURE AND INSTABILITY TO CONTINUE TO BUILD THROUGH THE
AFTERNOON. AS TEMPERATURES CLIMB THROUGH THE 90S F...AND STRONGER QG
FORCING ARRIVES ATOP THE VERY UNSTABLE WARM SECTOR...REMAINING
INHIBITION WILL FIRST BE OVERCOME ACROSS ERN/NERN ND WHERE RAPID TO
EXPLOSIVE TSTM DEVELOPMENT SHOULD ENSUE BEFORE LATE AFTERNOON.
ADDITIONAL SCATTERED DEVELOPMENT SWD/SWWD ACROSS THE WARM SECTOR MAY
OCCUR FROM LATE AFTERNOON THROUGH EARLY EVENING AS STRONG DYNAMIC
FORCING ASSOCIATED WITH THE TROUGH AND DRYLINE/FRONT ACT TO OVERCOME
THE CAP FROM NERN SD SWWD INTO THE NCNTRL PLAINS.

VERTICAL SHEAR AND FORCING WILL BE MORE THAN ADEQUATE FOR ORGANIZED
SEVERE STORMS WITH INITIAL ACTIVITY RAPIDLY BECOMING SUPERCELLULAR
AND PRODUCING VERY LARGE HAIL. FORECAST SOUNDINGS ALSO DEPICT
SUFFICIENT DIRECTIONAL SHEAR AND LOW LEVEL CAPE IN THE STORM UPDRAFT
LAYER FOR POTENTIALLY STRONG LOW-LEVEL MESOCYCLONES.  TORNADOES MAY
DEVELOP FROM DISCRETE STORMS PERSISTING NEAR RESIDUAL
OUTFLOW/DIFFERENTIAL HEATING BOUNDARIES...AS WELL AS FROM STRONG
UPDRAFT/DOWNDRAFT COUPLETS OCCURRING NEAR BREAKS IN ANY LINE
SEGMENTS. CONVECTION SHOULD TREND TOWARD SQUALL-LINEAR MODE INTO THE
EVENING WITH WIDESPREAD DAMAGING WINDS POSSIBLE AS STORM COVERAGE
INCREASES AND RESULTANT COLD POOLS STRENGTHEN AND MERGE. STRONG MID
LEVEL DRY PUNCH AND ENHANCED MESOSCALE ASCENT ON THE EDGE OF THE
PLAINS CAPPING INVERSION SHOULD MAINTAIN THE THREAT OF BOWING LINE
SEGMENTS...HAIL...AND ISOLATED/BRIEF TORNADOES ACROSS MN/NRN
IA...INTO WI...AND PERHAPS THE U.P. OF MI...INTO LATE SATURDAY
NIGHT/EARLY SUNDAY.

...NERN GULF COAST/SOUTHEAST...
VERY MOIST AND INCREASINGLY UNSTABLE AIR MASS WILL AGAIN SUPPORT THE
DEVELOPMENT OF NUMEROUS PULSE/MULTICELL STORMS ACROSS THESE AREAS
TODAY. WHILE WEAK SHEAR WILL LIMIT OVERALL ORGANIZATION... ACTIVITY
PERSISTING ALONG RESIDUAL FRONTAL BOUNDARY...AND ALSO AIDED BY LARGE
SCALE INFLUENCE OF WWD MOVING TROUGH OVER THE ERN GULF...WILL POSE
SOME THREAT FOR LOCALLY DAMAGING WINDS AND MARGINALLY SEVERE HAIL.

..CARBIN/GUYER.. 08/05/2006