[SWODY2] SWODY2

[Severe Weather Outlook - Day 2]

ACUS02 KWNS 250554
SWODY2
SPC AC 250553

DAY 2 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
1253 AM CDT TUE JUL 25 2006

VALID 261200Z - 271200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PORTIONS OF THE CNTRL
GRTLKS AND UPPER MS VLY REGIONS...

...SYNOPSIS...
MID-WEEK UPPER FLOW REGIME WILL MAINTAIN A BROAD UPPER HIGH ACROSS
THE SWRN STATES WITH A CENTER OVER THE GRT BASIN REGION.  A LARGELY
ZONAL PATTERN WILL EXIST ACROSS SRN CANADA AND THE EXTREME NRN PARTS
OF THE UNITED STATES.  THIS JET STREAM WILL CARRY NUMEROUS SHORTWAVE
TROUGHS ACROSS THE NRN TIER OF THE COUNTRY.  TWO FEATURES OF NOTE
WILL LIKELY MODULATE THE POTENTIAL FOR SEVERE WEATHER. ONE WILL BE
A FAIRLY STRONG MID-LEVEL IMPULSE...NOW EVOLVING OVER SRN CANADA. 
THIS FEATURE WILL MOVE ACROSS THE UPPER MS VLY/GRT LKS REGION ON
WED.  A SECOND WEAKER SHORTWAVE TROUGH WILL MOVE SEWD ACROSS MT BY
WED EVE.

AT THE SFC...A COLD FRONT ACCOMPANYING THE LEAD WAVE WILL MOVE SEWD
ACROSS THE UPPER MS VLY AND TO THE CNTRL GRTLKS REGION BY 12Z THU. 
TAIL END OF THIS FRONT WILL REDEVELOP QUICKLY NWD ACROSS THE HIGH
PLAINS DURING THE PERIOD.  A WEAK LEE-TROUGH WILL EXIST ACROSS THE
CNTRL PLAINS AND CORN BELT.

...CNTRL GRTLKS SWWD TO THE CNTRL PLAINS...
CONVECTION...LIKELY SUB-SEVERE...WILL BE ONGOING EARLY WED MORNING
ACROSS PARTS OF THE CNTRL GRTLKS SWWD INTO THE CORN BELT.  THIS
ACTIVITY WILL BE KEPT ALIVE THROUGH THE MORNING BY A WEAKENING SWLY
LLJ AXIS THAT WILL SHIFT NEWD INTO SRN ONT BY MID-DAY.

IN WAKE OF THE MORNING ACTIVITY...THE PRE-FRONTAL AIR MASS IS LIKELY
TO BECOME QUITE UNSTABLE OWING TO THE GRADUAL MOISTENING OF THE
BOUNDARY LAYER AND VERY STEEP MID-TROPOSPHERIC LAPSE RATES.  THE
PRIMARY FORCING FOR ASCENT ASSOCIATED WITH THE UPPER WAVE WILL
LIKELY BE PASSING ACROSS THE INSTABILITY AXIS BY EARLY AFTN...WITH
TSTMS LIKELY DEVELOPING ALONG/AHEAD OF THE COLD FRONT FROM PARTS OF
UPPER MI TO NERN IA.  VERTICAL SHEAR WILL GENERALLY BE LESS THAN
30-35 KTS...BUT EXPECTED MAGNITUDE OF LAPSE RATES AND MODEST VEERING
WINDS WITH HEIGHT SUGGEST THAT SUPERCELLS WILL BE POSSIBLE WITH
LARGE HAIL...DAMAGING WINDS AND POSSIBLY AN ISOLD TORNADO.
ACTIVITY SHOULD MOVE EWD DURING THE EVENING INTO THE CNTRL GRTLKS
REGION AND LIKELY WEAKEN AFTER DARK AS THEY MOVE INTO A MORE STABLE
ENVIRONMENT.

A SEPARATE REGION OF ENHANCED CONVECTION WILL LIKELY FAVOR PORTIONS
OF THE CNTRL PLAINS EWD INTO PARTS OF NRN MO AND CNTRL IL WHERE A
SECONDARY LOW-LEVEL THERMAL RIDGE SHOULD EXIST.  THIS WILL BE JUST S
OF MORNING CONVECTION AND AS THE BOUNDARY LAYER HEATS...LOCAL
CONVERGENCE ALONG THE LEE-TROUGH AND/OR OUTFLOW BOUNDARIES MAY SERVE
AS A FOCUS FOR TSTMS.  THOUGH THE VERTICAL SHEAR THIS FAR S WILL BE
MEAGER...LAPSE RATES WILL BE QUITE STEEP THROUGHOUT THE COLUMN AND
ISOLD STORMS MAY PRODUCE LARGE HAIL OR DAMAGING WIND GUSTS.

...HIGH PLAINS...
HIGH-BASED TSTMS WILL LIKELY DEVELOP ACROSS THE NRN HIGH
PLAINS...DOWNSTREAM FROM THE WEAKER SECONDARY IMPULSE DROPPING ESEWD
FROM THE SRN CANADIAN ROCKIES. A TONGUE OF INSTABILITY WILL LIKELY
ARC NWWD ALONG/N OF THE RETREATING SFC BOUNDARY AND COUPLED WITH
35-40 KTS OF 6KM SHEAR SUGGEST THAT ISOLD ORGANIZED STORMS MAY
EVOLVE FROM ERN MT INTO PARTS OF WRN ND WITH POSSIBLE HAIL AND GUSTY
WINDS.

OTHER STORMS WILL DEVELOP SWD ALONG THE ROCKIES DURING PEAK HEATING
AND MAY POSE AN ISOLD DAMAGING WIND THREAT GIVEN THE TYPICAL STEEP
LOW-LEVEL LAPSE RATES.

...SWRN DESERTS...
HIGHER PWAT VALUES SHOULD BE WELL-ESTABLISHED ACROSS THE LWR DESERTS
OWING TO HRCN EMILIA THAT WILL MOVE OFF THE WRN COAST OF BAJA
THROUGH WED. DEPENDING ON HOW MUCH RESIDUAL CONVECTIVE DEBRIS IS IN
PLACE ON WED...THERE COULD BE ANOTHER ROUND OF ORGANIZED TSTMS WED
AFTN/EVE.  IT APPEARS...THOUGH...THAT THE STRONGER ENELY FLOW WILL
EXIST ACROSS SONORA.  WILL MAINTAIN LOW SEVERE PROBABILITIES ATTM.

...MIDDLE/UPPER TX COAST...
THERE IS A WIDE SPREAD AMONG THE MODELS IN HANDLING THE TROPICAL
WAVE ACROSS THE WRN GULF BASIN.  CONSENSUS SUGGESTS THAT THE
STRONGEST CONVECTION SHOULD BE CONFINED TO THE COASTAL PLAINS AND
OFFSHORE WATERS.  FORECAST SOUNDINGS SHOW A HIGH PWAT AIRMASS WITH
SUFFICIENT LOW-LEVEL SHEAR FOR PERHAPS AN ISOLD TORNADO OR DAMAGING
WIND GUST.

..RACY.. 07/25/2006