DAY2SVR: Nws Storm Prediction Center Norman Ok

ACUS02 KWNS 120554
SWODY2
SPC AC 120553

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1253 AM CDT SAT MAY 12 2012

VALID 131200Z - 141200Z

...THERE IS A SLGT RISK OF SVR TSTMS FOR CNTRL/ERN NM AND FAR W TX
ON SAT AFTERNOON/EVENING...

...SYNOPSIS...
A DAMPENING MID-LEVEL IMPULSE OVER THE SRN PLAINS SHOULD WEAKEN
FURTHER AS IT EVOLVES TOWARDS THE OH/TN VALLEYS THROUGH EARLY MON.
ASSOCIATED WEAK SURFACE REFLECTION SHOULD TRACK FROM THE WRN GULF
COAST INTO PARTS OF THE DEEP SOUTH ALONG A SLOWLY ADVANCING WARM
FRONT. IN THE WEST...A SHORT WAVE IMPULSE OVER THE NRN ROCKIES
SHOULD AMPLIFY INTO THE ERN GREAT BASIN BY EARLY SUN AS A RIDGE
BUILDS IN THE WEST. THE IMPULSE WILL THEN TRACK MORE SLOWLY S/SEWD
ACROSS THE FOUR CORNERS INTO THE SOUTHWEST BY EARLY MON.

...CNTRL/ERN NM...FAR W TX...
A BELT OF ENHANCED MID-LEVEL W/NWLYS WILL ACCOMPANY THE SHORT WAVE
TROUGH APPROACHING FROM THE ERN GREAT BASIN...WITHIN A CONTINUED
UPSLOPE FLOW REGIME. THIS WILL RESULT IN FAVORABLE LARGE-SCALE
ASCENT AND WITH 40S TO LOWER 50S SURFACE DEW POINTS ACROSS THE SRN
HIGH PLAINS...MODEST BUOYANCY WILL BE SUFFICIENT FOR SCATTERED TSTMS
FORMING OFF THE HIGHER TERRAIN IN THE AFTERNOON. WITH THE REGION
LYING ON THE FRINGE OF STEEP MID-LEVEL LAPSE RATES...30-40 KT
EFFECTIVE SHEAR SHOULD BE SUFFICIENT FOR ROTATING UPDRAFTS PRIMARILY
PRODUCING LARGE HAIL AND ISOLATED SEVERE WIND DURING THE
AFTERNOON/EVENING. A FEW CLUSTERS SHOULD EVOLVE SEWD AND MAY YIELD
MARGINAL SEVERE PERSISTING INTO SAT NIGHT.

...DEEP SOUTH/TN VALLEY...
LOW CONFIDENCE REMAINS WITH REGARDS TO THE PHASING OF
THERMODYNAMIC/KINEMATIC PARAMETERS WITH SUBSTANTIAL VARIATION AMONG
SREF GUIDANCE. ETA-BASED KF AND WRF-ARW MEMBERS OF THE SREF ARE MORE
AGGRESSIVE WITH STRONGER LOW-LEVEL SLYS/MID-LEVEL SWLYS WHERE
SUFFICIENT BUOYANCY DEVELOPS FOR ORGANIZED CONVECTION. THIS REMAINS
IN CONTRAST TO THE MORE SUBDUED ETA-BASED BMJ AND WRF-NMM MEMBERS OF
THE SREF AND NAM/GFS GUIDANCE. GIVEN EXPECTED DAMPENING OF THE SRN
PLAINS SHORT WAVE IMPULSE...THE DEEPENING OF THE LOW-LEVEL WIND
FIELD APPEARS TO BE IN RESPONSE TO CONVECTIVE FEEDBACK ON D1. WITH
POTENTIAL ANTECEDENT CONVECTION BREEDING UNCERTAINTY IN FRONTAL
LOCATION/CHARACTER AS WELL...WILL DEFER ON ANY POTENTIAL UPGRADE TO
SLIGHT RISK.

..GRAMS.. 05/12/2012

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