[SWODY2] SWODY2

[Severe Weather Outlook - Day 2]

ACUS02 KWNS 261714
SWODY2
SPC AC 261713

DAY 2 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
1213 PM CDT SAT AUG 26 2006

VALID 271200Z - 281200Z

...THERE IS A SLGT RISK OF SVR TSTMS OVER THE UPPER OH VALLEY...

...THERE IS A SLGT RISK OF SVR TSTMS OVER SERN CO...SWRN KS...AND
THE OK/NRN TX PNHDLS...

...SYNOPSIS...

PROGRESSIVE WAVE TRAIN OF POLAR WESTERLIES WILL CONTINUE ACROSS
CANADA THIS FORECAST PERIOD.  A LOWER LATITUDE TROUGH OVER THE
INTERMOUNTAIN W WILL GRADUALLY SHIFT EWD INTO THE CNTRL PLAINS IN
RESPONSE TO THE APPROACH OF A STRONG UPSTREAM SYSTEM FROM THE GULF
OF AK. IN THE LOW-LEVELS...SURFACE LOW PRESSURE OVER LOWER MI
SUNDAY MORNING WILL DEVELOP EWD INTO N-CNTRL PA BY SUNDAY NIGHT WITH
A TRAILING BAROCLINIC ZONE STRETCHING WWD THROUGH THE OH VALLEY TO
SECONDARY LOW PRESSURE DEVELOPING NEWD FROM OK INTO SWRN MO.  THE
WRN EXTENSION OF THIS BOUNDARY WILL GRADUALLY SHIFT SWD THROUGH THE
SRN HIGH PLAINS.

...UPPER OH VALLEY...

AIR MASS DESTABILIZATION IS EXPECTED TO BE TEMPERED BY CONSIDERABLE
CLOUDS AND PRECIPITATION SUNDAY IN ADVANCE OF SURFACE LOW AND
ATTENDANT FRONT SHIFTING EWD THROUGH THE REGION.  HOWEVER...THE
PRESENCE OF A MOIST LOW-LEVEL AIR MASS CHARACTERIZED BY DEWPOINTS IN
THE UPPER 60S TO LOW 70S COUPLED WITH SOME DIABATIC HEATING WILL
LIKELY RESULT IN POCKETS OF MODERATE INSTABILITY WITH MLCAPES
APPROACHING 1000-1500 J/KG.  TSTMS ARE FORECAST TO INCREASE IN
COVERAGE AND INTENSITY BY EARLY AFTERNOON FROM WRN PARTS OF NY/PA
SWWD INTO CNTRL OH AS SURFACE FRONT ENCOUNTERS DESTABILIZING AIR
MASS...AND DEEPER LAYER FORCING FOR ASCENT IS ENHANCED BY WEAK
IMPULSES MOVING THROUGH THE OH VALLEY.

MODEST LOW-LEVEL VEERING WIND PROFILES WITH 30-40 KTS OF WNWLY
MID-LEVEL FLOW WILL RESULT IN SUFFICIENT VERTICAL SHEAR FOR A FEW
ORGANIZED SEVERE STORMS INCLUDING SUPERCELLS CAPABLE OF SEVERE
HAIL...DAMAGING WINDS AND PERHAPS A COUPLE OF TORNADOES.  ERN EXTENT
OF SEVERE THREAT WILL BE LIMITED BY STABLE LOW-LEVEL TRAJECTORIES
ORIGINATING FROM SURFACE HIGH OVER THE CANADIAN MARITIMES.

...SERN CO/SWRN KS/OK AND TX PNHDLS...

LOW-LEVEL AIR MASS IS NOT EXPECTED TO BECOME PARTICULARLY WARM OWING
TO SOURCE REGION BEING CONVECTIVELY PROCESSED AIR ORIGINATING OVER
OK AND THE ERN OK/TX PNHDLS.  HOWEVER...DAYTIME HEATING COUPLED WITH
HEIGHT FALLS/DYNAMIC COOLING AHEAD OF UPPER SYSTEM MOVING THROUGH
THE CNTRL ROCKIES WILL CONTRIBUTE TO MODIFICATION VIA STEEPENING LOW
TO MID LEVEL LAPSE RATES WITH RESULTANT MLCAPES APPROACHING 500-1500
J/KG.  WEAK LEE CYCLOGENESIS OCCURRING OVER SERN CO WILL LIKELY
RESULT IN SUFFICIENT LOW-LEVEL CONVERGENCE TO INITIATE TSTMS BY MID
TO LATE AFTERNOON WITH ACTIVITY MOVING/DEVELOPING EWD OR SEWD INTO
SWRN KS/OK AND TX PNHDLS SUNDAY NIGHT.

DESPITE THE MODEST INSTABILITY...THE INCREASED LARGE-SCALE FORCING
FOR ASCENT AND 40-50 KTS OF EFFECTIVE BULK SHEAR SHOULD SUPPORT
ORGANIZED...ROTATING UPDRAFTS WITH THE PRIMARY THREAT BEING SEVERE
HAIL.  A TORNADO OR TWO ALSO WILL BE POSSIBLE IN ADDITION TO LOCALLY
DAMAGING WINDS.

...OK/NRN TX INTO THE MID MS VALLEY...

CONSIDERABLE UNCERTAINTY EXISTS WITH REGARD TO CONVECTIVE INITIATION
AND EVOLUTION THROUGH THE FORECAST OWING TO COMPLICATING EFFECTS
ANTECEDENT CONVECTION AND RESULTANT LOCATION OF SURFACE BOUNDARIES. 
AS SUCH...A HOT AND MOIST LOW-LEVEL AIR MASS WILL ONCE AGAIN DEVELOP
ACROSS WARM SECTOR...SUPPORTING MLCAPES OF 2000-3000 J/KG.  IT
APPEARS THAT THE STRONGER VERTICAL SHEAR WILL LIKELY EXIST N OF
PRIMARY LOW-LEVEL BAROCLINIC ZONE WITH GENERALLY 20-30 KTS OF DEEP
LAYER SHEAR ANTICIPATED ACROSS AREA OF STRONGEST AIR MASS
DESTABILIZATION.  THIS ENVIRONMENT SHOULD SUPPORT ORGANIZED
MULTICELL CLUSTERS CAPABLE OF SOME HAIL AND DAMAGING WINDS THROUGH
THE AFTERNOON AND EVENING HOURS.

ONCE FINER SCALE DETAILS BECOME MORE CLEAR...PARTS OF AREA MAY NEED
TO BE UPGRADED TO A SLIGHT RISK.

..MEAD.. 08/26/2006