[SWODY1] SWODY1

[Severe Weather Outlook Day 1]

ACUS01 KWNS 181623
SWODY1
SPC AC 181621

DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
1021 AM CST SAT MAR 18 2006

VALID 181630Z - 191200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS WRN INTO CENTRAL TX...

...SRN PLAINS...
STRONG UPPER LOW NOW OVER THE LOWER CO RIVER VALLEY WILL MOVE LITTLE
DURING THE PERIOD...MAINTAINING BROAD ZONE OF MODERATE TO STRONG
SWLY FLOW ALOFT ACROSS THE SRN PLAINS. MUCH OF THE SRN PLAINS
REMAINS WITHIN COOL/STABLE BOUNDARY LAYER BEHIND QUASI-STATIONARY
SURFACE FRONT NOW EXTENDING FROM THE UPPER TX COAST INTO THE BIG
BEND REGION/FAR SWRN TX.  MODELS ARE CONSISTENT ON MAINTAINING A
SIMILAR FRONTAL POSITION FOR MUCH OF THE PERIOD.  THIS WILL LIMIT
SURFACE MOISTURE RETURN TO THE HILL COUNTRY INTO THE TRANS-PECOS
REGION TODAY...WHERE LOWER TO MID 60F SURFACE DEW POINTS SHOULD BE
IN PLACE THROUGH THE AFTERNOON.

DEEP CONVECTION HAS BEEN INCREASING ACROSS THE TX PANHANDLE AND
SOUTH OF THE RED RIVER THIS MORNING WITHIN ZONE OF STRONG
SLOPED/ISENTROPIC ASCENT...WITH A LARGE MCS IN NCNTRL TX. ACTIVITY
IS EXPECTED TO BE SUSTAINED BY MORE FAVORABLE LARGE SCALE FORCING
THAN YESTERDAY. LATEST ENSEMBLE MEAN FCST INDICATES THAT MASS INFLOW
ON MODEST LLJ WILL PERSIST FROM NWRN TX TO THE RED RIVER THROUGH THE
DAY AS MID LEVEL FLOW AND UPPER DIFFLUENCE STRENGTHEN ACROSS THE SRN
PLAINS. MORNING SOUNDINGS FROM AMA AND MAF DISPLAYED STEEP 3-6KM
LAPSE RATES OF 7.6C/KM IN ELEVATED MIXED LAYER ALONG WITH EFFECTIVE
SHEAR IN EXCESS OF 60KT. GIVEN THE LIKELIHOOD OF INCREASING
CONVECTION WITHIN STRENGTHENING WARM CONVEYOR...COUPLED WITH
UPSTREAM LAPSE RATES AND SHEAR...THE CHANCE FOR ELEVATED AND
EMBEDDED SUPERCELLS PRODUCING SEVERE HAIL SHOULD INCREASE THROUGH
THE DAY.

IN THE WAKE OF ONGOING STORMS...CLOUDS WILL HINDER SURFACE HEATING
MUCH MORE THAN YESTERDAY NEAR THE NWRN EDGE OF SURFACE DEW POINT
AXIS. THIS SUGGESTS AFTERNOON/EVENING DEVELOPMENT WILL BE LESS
DRIVEN BY HEATING...AND MORE SUPPORTED BY WEAK DISTURBANCES EJECTING
AWAY FROM BROAD WRN U.S. UPPER TROUGH. NOTHING IS EVIDENT IN
MORNING SAT IMAGERY.  HOWEVER...MORNING GUIDANCE CONTINUES TO
INDICATE DEVELOPMENT OF ONE OR MORE MCSS THIS EVENING/OVERNIGHT AS A
WEAK IMPULSE LIFTS ENEWD INTO WRN AND CENTRAL TX.  VERY STEEP LAPSE
RATES AND STRONG CLOUD-LAYER SHEAR WILL SUPPORT RENEWED SEVERE
DEVELOPMENT WITH NEXT ROUND OF STORMS LATER TODAY AND TONIGHT WITH
PRIMARY THREAT OF LARGE HAIL.  SHOULD BREAKS IN OVERCAST ALLOW AMPLE
HEATING INTO FAR SWRN TX...A SURFACE-BASED SUPERCELL OR TWO MAY
DEVELOP ENEWD ACROSS THE TRANS PECOS THIS EVENING.

..EVANS/TAYLOR/CARBIN.. 03/18/2006