[SWODY1] SWODY1

[Severe Weather Outlook Day 1]

ACUS01 KWNS 201948
SWODY1
SPC AC 201946

DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
0246 PM CDT THU APR 20 2006

VALID 202000Z - 211200Z

...THERE IS A SLGT RISK OF SVR TSTMS FROM SWRN TX INTO ERN TN...

...TX...

A LARGE CLUSTER OF THUNDERSTORMS HAS EVOLVED FROM THE HILL COUNTRY
OF CNTRL TX INTO THE TX SOUTH PLAINS NEAR LBB. THIS ACTIVITY IS
DRIVEN IN LARGE PART DUE TO LOW LEVEL WARM ADVECTION ATOP ENTRENCHED
COOLER LOW LEVEL BOUNDARY LAYER WHERE ENELY SFC WINDS PERSIST. LLJ
WILL REMAIN FOCUSED INTO SWRN TX FOR THE NEXT FEW HOURS BEFORE
GRADUALLY VEERING INTO CNTRL TX LATER THIS EVENING.  IN THE SHORT
TERM...CONTINUED HEATING WILL BE REQUIRED OVER NRN MEXICO...EWD
ALONG THE WARM FRONT BEFORE MORE ROBUST WARM SECTOR CONVECTION WILL
EVOLVE.  UPDRAFT CLUSTERS ARE GRADUALLY LOWERING JUST NORTH OF THE
WIND SHIFT OVER GILLESPIE COUNTY TX...WITH A NOTABLE EWD PROPAGATION
ALIGNED ALONG FRONTAL ORIENTATION.  SHEAR PROFILES REMAIN FAVORABLE
FOR SUPERCELL DEVELOPMENT AND WITH TIME POTENTIALLY
TORNADIC...ALTHOUGH LARGE HAIL SHOULD BE THE PRIMARY SEVERE THREAT. 
LATER TONIGHT...CLUSTER MERGERS AND GRADUALLY VEERING WINDS WITH
HEIGHT SHOULD ENHANCE FORWARD PROPAGATION COMPONENT AND DAMAGING
WINDS MAY BECOME MORE OF AN ISSUE AS MCS EVOLVES AND SPREADS TOWARD
THE MIDDLE/UPPER TX COAST.

...SERN AR TO NRN AL...

ISOLATED SEVERE THUNDERSTORMS ARE EVOLVING OVER SERN AR...WITH
MOVEMENT EXPECTED INTO NWRN MS SHORTLY.  THIS ACTIVITY IS DEVELOPING
WITHIN A FAIRLY UNSTABLE AIRMASS...SBCAPES ON THE ORDER OF
2000-3000J/KG...WHERE BOUNDARY LAYER INSTABILITY/LAPSE RATES HAVE
INCREASED MARKEDLY OVER THE LAST FEW HOURS.  SCATTERED SUPERCELLS
SHOULD CONTINUE TO DEVELOP AND SPREAD NEWD ACROSS NRN MS INTO NRN AL
ALONG OUTFLOW REMNANTS FROM EARLIER CONVECTIVE ACTIVITY.  ADDITIONAL
STORMS ARE DEVELOPING WELL EAST INTO NRN AL AT THIS TIME...ALONG
MOST PROGRESSIVE PORTION OF WIND SHIFT.  THIS BOUNDARY SHOULD
ENHANCE THE SUPERCELL THREAT WHILE STEEP LAPSE RATE ENVIRONMENT/CAPE
WILL CONTRIBUTE TO THE POTENTIAL FOR VERY LARGE HAIL.  UPSTREAM
CONVECTION THAT DEVELOPS ACROSS THE ARKLATEX REGION THIS EVENING MAY
SPREAD EAST OF THE MS RIVER INTO NRN MS/WRN TN TOWARD THE END OF THE
PERIOD...HOWEVER MORE SIGNIFICANT CONVECTION SHOULD OCCUR WITH THE
MORE DIURNALLY DRIVEN STORMS THIS AFTERNOON INTO EARLY EVENING.

..DARROW.. 04/20/2006