[SWODY1] SWODY1

[Severe Weather Outlook Day 1]

ACUS01 KWNS 280557
SWODY1
SPC AC 280555

DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
1255 AM CDT SUN MAY 28 2006

VALID 281200Z - 291200Z

...THERE IS A SLGT RISK OF SVR TSTMS FROM WRN/NRN NEB ACROSS THE ERN
DAKOTAS AND WRN MN...

...SYNOPSIS...
STRONGLY AMPLIFIED MID/UPPER LEVEL FLOW PATTERN WILL FEATURE A LARGE
SUMMER-LIKE RIDGE ACROSS MUCH OF THE EAST...AND A RELATIVELY DEEP
TROUGH ACROSS THE WEST AND ROCKIES. SHORT WAVE IMPULSES EMANATING
FROM THE WRN TROUGH AND ENCOUNTERING STRONG DOWNSTREAM RIDGING HAVE
BEEN LIFTING NNEWD/NEWD ACROSS THE HIGH PLAINS AND UPPER MS VALLEY
OVER THE WEEKEND AND DRIVING MCS DEVELOPMENT ACROSS THESE AREAS...AS
WELL AS ACROSS SCNTRL CANADA. EXTENSIVE PLUME OF WARM AIR ALOFT
COVERING MUCH OF THE GREAT PLAINS AND PARTS OF THE MIDWEST HAS
LIMITED MORE WIDESPREAD TSTM DEVELOPMENT OVER THESE REGIONS DESPITE
PRONOUNCED DIURNAL DESTABILIZATION. SIMILAR CONDITIONS WILL PERSIST
TODAY.

A STRONG IMPULSE/SPEED MAX CURRENTLY CROSSING THE SRN GREAT BASIN IS
FORECAST TO PIVOT NEWD AROUND THE ERN FLANK OF THE LARGE SCALE WRN
TROUGH AND PRODUCE MODEST HEIGHT FALLS FROM CO TO THE WRN DAKOTAS
THROUGH SUNDAY NIGHT. SHARP BAROCLINIC ZONE...ALIGNED WITH
DEEP-LAYER MERIDIONAL FLOW FROM CO TO ND...WILL PROVIDE FOCUS FOR
TRIPLE POINT LOW FORMATION ON COLD FRONT/DRYLINE/STATIONARY FRONT
INTERSECTION NERN CO TO WRN/CNTRL NEB PNHDL DURING LATE AFTERNOON AS
WRN IMPULSE APPROACHES. ANOTHER SURFACE LOW WILL BE SITUATED ON THE
BOUNDARY OVER ERN ND...ASSOCIATED WITH A LEADING IMPULSE LIFTING
INTO SRN CANADA. THE ND LOW IS FORECAST TO TRACK INTO SRN MANITOBA
THROUGH THE EVENING WHILE CO/NEB SURFACE LOW MOVES NEWD ACROSS TO
NRN NEB...AND THEN TO ERN SD/WRN MN THROUGH MONDAY MORNING. COLD
FRONT ASSOCIATED WITH THE NEB LOW WILL SURGE SWD ACROSS THE CNTRL
HIGH PLAINS TO SWRN KS BY THE END OF THE FORECAST PERIOD.

...NEB/DAKOTAS...
VERY STRONG TO EXTREME WARM SECTOR INSTABILITY WILL AGAIN DEVELOP
FROM CNTRL/ERN NEB NWD ACROSS ND/MN THIS AFTERNOON WITH MLCAPE
VALUES IN THIS CORRIDOR AOA 2500 J/KG. DESPITE TEMPERATURES CLIMBING
INTO THE 90S ACROSS THE WARM SECTOR...CONVECTIVE INHIBITION WILL
AGAIN LIMIT SURFACE-BASED STORM DEVELOPMENT TO THOSE AREAS WHERE
EITHER EXCESSIVE HEATING/MIXING...AND/OR PERSISTENT STRONG FORCING
CAN OVERCOME THE CAP. MOST LIKELY AREAS TO EXPERIENCE THESE
CONDITIONS...LEADING TO SURFACE-BASED TSTM INITIATION...APPEAR TO BE
NEAR THE LEADING SURFACE LOW OVER NERN ND...AND NEAR TRIPLE POINT
LOW MOVING TOWARD NCNTRL NEB DURING THE EVENING. STORMS DEVELOPING
NEAR THESE FEATURES WILL ENCOUNTER SUFFICIENT SHEAR AND INSTABILITY
FOR ORGANIZATION/PERSISTENCE WITH VERY LARGE HAIL/HIGH WINDS...AND
PERHAPS AN ISOLATED TORNADO OR TWO.

LATEST DETERMINISTIC AND ENSEMBLE GUIDANCE SUGGESTS THAT GREATER
STORM COVERAGE IS MORE LIKELY TO OCCUR ON THE COOLER/DRIER SIDE OF
THE FRONTAL ZONE...FROM NERN CO/WRN NEB ACROSS CNTRL SD THROUGH THE
LATE NIGHT. THIS SCENARIO APPEARS REALISTIC GIVEN STRONGER HEIGHT
FALLS TO THE WEST OF THE DEEP LAYER BAROCLINIC ZONE... MERIDIONAL
CONFIGURATION OF THE LARGER SCALE SYSTEM...AND STRENGTH OF THE CAP.
EVEN THOUGH THIS POST-FRONTAL ACTIVITY MAY BE ROOTED ABOVE A MORE
STABLE BOUNDARY LAYER...EXTREME SHEAR...STRONG FORCING...AND STEEP
LAPSE RATES SHOULD RESULT IN NUMEROUS INTENSE STORMS/SUPERCELLS WITH
LARGE HAIL POTENTIAL. AS THIS CONVECTION EVOLVES INTO AN MCS AND
SPREADS NEWD ACROSS NEB/SD THROUGH LATE TONIGHT...OUTFLOW REINFORCED
FRONTAL SURGE MAY PROVE SUFFICIENT TO PROMOTE ADDITIONAL HIGH-BASED
TSTMS...WITH SOME WIND AND HAIL THREAT SPREADING EAST TO ERN NEB AND
WRN MN THROUGH EARLY MONDAY.

...DRYLINE FROM SRN NEB TO WEST TX...
STRONG HEATING/MIXING WILL AGAIN PRODUCE POCKETS OF MESOSCALE
FORCING SUFFICIENT FOR ISOLATED HIGH-BASED TSTM DEVELOPMENT BY LATE
AFTERNOON THESE AREAS. UNLIKE SATURDAY AFTERNOON...GRADUAL HEIGHT
RISES AND GENERALLY WEAKER MID LEVEL FLOW/SHEAR MAY TEND TO LIMIT
OVERALL STORM COVERAGE/INTENSITY AND ONLY A LOW PROBABILITY
WIND/HAIL THREAT APPEARS WARRANTED FOR THE DRYLINE TODAY.

...TX/LA GULF COAST TO LOWER MS VALLEY...
WEAK IMPULSE/MCV CURRENTLY TRACKING EWD ACROSS SOUTH TX COULD
ENHANCE TSTM POTENTIAL IN VERY MOIST UNSTABLE GULF COAST AIR MASS.
STRONG INFLUX OF GULF MOISTURE AROUND SWRN FLANK OF EAST COAST
ANTICYCLONE WILL FUEL A FEW INTENSE STORM CLUSTERS SPREADING INLAND
SIMILAR TO SATURDAY ACROSS LA. A COUPLE OF HAIL EVENTS AND A FEW WET
MICRO BURSTS APPEAR POSSIBLE.

....FL/AL/GA...
RESIDUAL FRONT SITUATED ACROSS AL/GA BORDER MAY AGAIN PROVIDE A
FOCUS FOR AFTERNOON STORMS IN VERY UNSTABLE AND WEAKLY CAPPED
ENVIRONMENT. ADDITIONALLY...STRONG INSTABILITY AND SEA/GULF BREEZE
COLLISION ACROSS FL WILL RESULT IN NUMEROUS STRONG STORMS OVER THE
PENINSULA. DESPITE LIMITED SHEAR...STORM MERGERS AND BOUNDARY
INTERACTIONS IN VERY MOIST AND UNSTABLE REGIME SHOULD RESULT IN A
FEW SEVERE WIND/HAIL EVENTS.

..CARBIN/GUYER.. 05/28/2006