DAY3SVR: Nws Storm Prediction Center Norman Ok

ACUS03 KWNS 070731
SWODY3
SPC AC 070729

DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0229 AM CDT SUN APR 07 2013

VALID 091200Z - 101200Z

...THERE IS A SLGT RISK OF SVR TSTMS FROM THE LOWER MO VALLEY TO THE
SRN PLAINS...

...SYNOPSIS...
HIGHLY AMPLIFIED UPPER-LEVEL TROUGH OVER THE WEST SHOULD EVOLVE INTO
TWO DISTINCT SHORTWAVE IMPULSES...ONE MOVING NEWD TOWARDS THE
NRN/CNTRL PLAINS AND THE OTHER REMAINING IN THE BASE OF THE TROUGH
OVER NWRN MEXICO. MID-LEVEL SWLYS WILL INCREASE ACROSS THE
WARM/MOIST SECTOR IN RESPONSE TO THE LEAD IMPULSE. AT THE
SURFACE...CYCLONE IN THE LEE OF THE SRN ROCKIES SHOULD DEVELOP NEWD
AND REACH THE LOWER MO VALLEY BY TUE NIGHT. THE SRN PLAINS DRYLINE
WILL BE PROGRESSIVELY OVERTAKEN BY A COLD FRONT WHICH SHOULD REACH
CNTRL TX BY EARLY WED.

...LOWER MO VALLEY TO THE SRN PLAINS...
A BROAD CORRIDOR OF ORGANIZED SEVERE POTENTIAL WITH ALL HAZARD TYPES
IS ANTICIPATED TUE AFTERNOON INTO WED MORNING. AN UPGRADE TO
MODERATE RISK WILL CONTINUE TO BE CONSIDERED IN LATER OUTLOOKS.

LOW CONFIDENCE EXISTS IN THE SYNOPTIC PATTERN GIVEN RELATIVELY LARGE
SPREAD IN GUIDANCE WITH THE HANDLING OF THE LEAD SHORTWAVE IMPULSE
EJECTING FROM THE WRN CONUS TROUGH. NCEP GUIDANCE REMAINS FASTER
THAN THE ECMWF/UKMET WITH THE PROGRESSION OF THE IMPULSE WHICH
AFFECTS POSITIONING OF THE DRYLINE/COLD FRONT...AND MORE BULLISH
WITH THE AMPLITUDE OF KINEMATICS OVER THE WARM/MOIST SECTOR. THIS
BREEDS SUBSTANTIAL UNCERTAINTY OVER WHERE TO PLACE HIGHER SEVERE
PROBABILITIES OR EVEN WHETHER THEY ARE NEEDED BEYOND AN ENHANCED
SLIGHT RISK.

REGARDLESS OF THE PATTERN DIFFERENCES...GIVEN STRENGTHENING RETURN
FLOW IN THE WRN GULF...A MODERATELY UNSTABLE AIR MASS WILL BECOME
MORE WIDESPREAD IN THE S-CNTRL CONUS. WITH STEEP MID-LEVEL LAPSE
RATES AND FORCING FOR ASCENT INCREASING THROUGH THE
PERIOD...SUPERCELLS AND ORGANIZED CLUSTERS SHOULD COMMENCE TUE
AFTERNOON IN PARTS OF KS AND DEVELOP S/EWD INTO THE SRN PLAINS AND
TOWARDS THE MID-MS VALLEY DURING THE EVENING/OVERNIGHT. LARGE HAIL
/SOME SIGNIFICANT/ AND TORNADOES WILL LIKELY BE THE PRIMARY HAZARDS.
WHILE THE THREAT FOR DAMAGING WINDS SHOULD INCREASE DURING THE
LATTER HALF OF THE PERIOD AS LOWER-LEVEL FLOW STRENGTHENS AND
CONVECTIVE MODE BECOMES MORE CLUSTER/LINEAR.

..GRAMS.. 04/07/2013

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