DAY2SVR: Nws Storm Prediction Center Norman Ok

ACUS02 KWNS 071732
SWODY2
SPC AC 071731

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1231 PM CDT FRI JUN 07 2013

VALID 081200Z - 091200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE MID-LOWER
MO VALLEY THROUGH THE CENTRAL PLAINS TO SRN HIGH PLAINS...

...SYNOPSIS...
ERN U.S. SYNOPTIC TROUGH IS FORECAST TO DEAMPLIFY SATURDAY WHILE A
SHORTWAVE TROUGH...CURRENTLY MOVING THROUGH THE CENTRAL GULF COAST
STATES TRACKS NEWD THROUGH NC/VA AND OFF THE MID ATLANTIC COAST TO
SRN NEW ENGLAND BY SATURDAY EVENING. AN UPSTREAM SHORTWAVE TROUGH
WILL DIVE SEWD INTO THE NRN/CNTRL PLAINS ALONG NERN PERIPHERY OF WRN
U.S. UPPER RIDGE BUILDING EWD ACROSS THE GREAT BASIN AND SRN
ROCKIES. THIS FEATURE WILL INDUCE A SURFACE LOW OVER THE CNTRL
PLAINS THAT WILL LIFT NEWD INTO THE UPPER MS VALLEY SATURDAY NIGHT.
OCCLUDED FRONT NORTH OF LOW WILL MOVE EWD THROUGH THE NRN PLAINS
WITH A COLD FRONT ADVANCING SEWD/SWD THROUGH THE CNTRL
PLAINS...WHILE A WARM FRONT DEVELOPS NEWD THROUGH THE MID-UPPER MS
VALLEY REGION.

...LOWER-MID MO VALLEY...CENTRAL PLAINS TO SRN HIGH PLAINS...
AN MCS SHOULD BE ONGOING AT 12Z SATURDAY ACROSS THE MID MO VALLEY OF
SERN SD/ERN NEB INTO WRN IA WITHIN A ZONE OF WAA IN THE NOSE OF A
40-45 KT SWLY LLJ AND BENEATH DIFFLUENT FLOW ALOFT. LOW LEVEL MASS
RESPONSE TO THE AMPLIFYING TROUGH/HEIGHT FALLS ACROSS THE
CENTRAL/NRN PLAINS TO UPPER MS VALLEY WILL LIMIT THE DIURNAL
WEAKENING TENDENCY OF THE LLJ...WITH AFOREMENTIONED WIND SPEEDS
EXPECTED TO BE MAINTAINED SATURDAY MORNING/AFTERNOON. THIS LLJ WILL
RESULT IN FURTHER MOISTURE/WARM AIR ADVECTION INTO THE MID-LOWER MO
AND PARTS OF THE UPPER MS VALLEYS...AIDING IN THE SUSTENANCE OF THE
MORNING MCS ACROSS ERN NEB INTO WRN-CENTRAL IA INTO SATURDAY
AFTERNOON.

NEW TSTM DEVELOPMENT IS EXPECTED BY SATURDAY AFTERNOON ALONG THE
SRN-WRN PERIPHERIES OF THE MORNING MCS AND ALONG THE SEWD/SWD
ADVANCING COLD FRONT THROUGH THE CENTRAL PLAINS. THESE NEW STORMS
WILL DEVELOP AS THE WARM SECTOR DESTABILIZES DUE TO MOISTURE
RETURN...WAA ALONG THE LLJ AND SURFACE HEATING BENEATH A PLUME OF
STEEPER MIDLEVEL LAPSE RATES AND FORCING FOR ASCENT IN THE EXIT
REGION OF A 50-60 KT NWLY 500 MB JET. THIS LATTER FEATURE COMBINED
WITH THE LLJ WILL RESULT IN EFFECTIVE BULK SHEAR OF 25-35 KT
SUGGESTING BOTH MULTICELLS AND SUPERCELLS WILL BE POSSIBLE. ALL
FACETS OF SEVERE WEATHER ARE EXPECTED ACROSS CENTRAL/ERN PARTS OF
NEB/KS INTO WRN IA/NWRN MO INCLUDING A FEW TORNADOES...GIVEN
PROXIMITY TO LOWER LCLS AND STRONGER LLJ/LARGER LOW LEVEL HODOGRAPH
CURVATURE.

FARTHER SSW ALONG THE COLD FRONT INTO SWRN KS AND THE DRY LINE SWD
THROUGH THE OK/TX PANHANDLES TO W TX...STRONGER INSTABILITY AND
7.5-8 C/KM MIDLEVEL LAPSE RATES WILL AID IN TSTM DEVELOPMENT ALONG
THESE BOUNDARIES AS THE SRN EXTENT OF THE CENTRAL PLAINS TROUGH
REACHES THESE AREAS BY PEAK HEATING. EFFECTIVE BULK SHEAR IS
FORECAST TO BE STRONGER ACROSS THE CENTRAL/SRN HIGH PLAINS
SUPPORTING SUPERCELLS AS THE PRIMARY STORM MODE WITH HAIL AND
DAMAGING WINDS THE PRIMARY THREATS. SOME MODELS SUGGEST A LITTLE
MORE OF NWRN-WRN OK AND THE REST OF THE TX PANHANDLE COULD HAVE A
THREAT FOR SEVERE STORMS AS AFTERNOON ACTIVITY SPREADS INTO THESE
REGIONS PRIOR TO BOUNDARY LAYER STABILIZATION WITH THE LOSS OF
STRONGER DAY TIME HEATING. THUS...THE SEVERE PROBABILITIES AND
CATEGORICAL SLIGHT RISK HAVE BEEN EXPANDED A LITTLE EWD.

...NRN PLAINS...
TSTMS SHOULD DEVELOP ALONG THE EWD MOVING OCCLUDED FRONT IN ND/SD
WHERE THE ENVIRONMENT WILL BE MARGINALLY UNSTABLE. WEAK BULK SHEAR
SUGGESTS STORMS SHOULD TEND TO REMAIN UNORGANIZED...AND LIMIT THE
THREAT FOR SEVERE STORMS. GIVEN THE WEAK CAPE/SHEAR PARAMETER
SPACE...THIS OUTLOOK WILL NOT INTRODUCE ANY SEVERE PROBABILITIES.

...CAROLINAS INTO SERN VA...
30-40 KT SWLY MIDLEVEL WINDS/SHEAR ACCOMPANYING THE CENTRAL GULF
COAST STATES SHORTWAVE TROUGH AND THE DEVELOPMENT OF MODERATE
INSTABILITY WILL SUPPORT TSTM DEVELOPMENT ACROSS THESE AREAS
SATURDAY. UNCERTAINTY WITH THE DEGREE OF FORCING ALOFT WITH THE
PROGRESSIVE TROUGH PRECLUDES THE INCLUSION OF HIGHER SVR
PROBABILITIES AND A CATEGORICAL SLIGHT RISK AT THIS TIME. A FEW
STRONG DAMAGING WINDS AND/OR HAIL WILL BE POSSIBLE GIVEN THE
PRESENCE OF 30-40 KT OF BULK SHEAR AND MODERATE INSTABILITY.

..PETERS.. 06/07/2013

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