Saturday, May 12, 2012

DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 121242
SWODY1
SPC AC 121240

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0740 AM CDT SAT MAY 12 2012

VALID 121300Z - 131200Z

...NO SVR TSTM AREAS FORECAST...

...LOWER MS/TN VALLEY REGION THROUGH EARLY TONIGHT...
A WEAKENING MIDLEVEL LOW NEAR TXK WILL CONTINUE TO EVOLVE INTO AN
OPEN WAVE WHILE MOVING SLOWLY EWD OVER THE LOWER MS VALLEY. ONLY A
WEAK SURFACE REFLECTION OF THE MIDLEVEL WAVE IS PRESENT...AND
LIKEWISE...LOW-LEVEL MASS RESPONSE IN THE WARM SECTOR IS EXPECTED TO
REMAIN RATHER WEAK. MEANWHILE...WIDESPREAD CONVECTION FROM PREVIOUS
DAYS AND ONGOING STORMS FROM THE TX COAST INTO WRN LA WILL CONTINUE
TO LIMIT LAPSE RATE PROFILES AND CONTRIBUTE TO SUBSTANTIAL CLOUD
COVER. THE NET RESULT WILL BE A WEAKLY UNSTABLE WARM SECTOR WITH
ONLY MODEST LOW-MIDLEVEL VERTICAL SHEAR.

THE RICHEST BOUNDARY LAYER MOISTURE /DEWPOINTS IN THE UPPER 60S/
WILL BE CONFINED TO THE I-10 CORRIDOR...WHILE THE SOMEWHAT STRONGER
VERTICAL SHEAR WILL ACCOMPANY A WEAK SURFACE WAVE THAT IS FORECAST
TO DEVELOP NEWD FROM LA TO THE TN VALLEY BY TONIGHT. NEITHER
INSTABILITY NOR VERTICAL SHEAR WILL BE PARTICULARLY STRONG BASED ON
THE AFOREMENTIONED REASONING...AND PHASING OF THE TWO WILL ALSO BE
POOR. AN ENVIRONMENT CHARACTERIZED BY MLCAPE OF 500-1500
J/KG...EFFECTIVE BULK SHEAR NEAR 30 KT...AND EFFECTIVE SRH OF
100-150 M2/S2 COULD SUPPORT A LOW END DAMAGING WIND/TORNADO RISK
ACROSS THE LOWER MS VALLEY...THOUGH THE THREAT SHOULD REMAIN
INSUFFICIENT FOR A CATEGORICAL OUTLOOK AREA.

...SRN ROCKIES THIS AFTERNOON/EVENING...
A WEAK LOW-LEVEL UPSLOPE FLOW REGIME IS EXPECTED THIS AFTERNOON
ACROSS NM/SRN CO...AS A SERIES OF DIFFUSE SHORTWAVE TROUGHS PROGRESS
EWD/ESEWD FROM THE GREAT BASIN TO THE CENTRAL/SRN ROCKIES. DESPITE
BOUNDARY LAYER DEWPOINTS GENERALLY IN THE LOWER 40S THIS
MORNING...DAYTIME HEATING AND THE ERN FRINGE OF THE STEEPER LAPSE
RATE PLUME WILL CONTRIBUTE TO AFTERNOON MLCAPE OF 250-500 J/KG.
DEEP-LAYER VERTICAL SHEAR WILL BE AT LEAST MARGINALLY FAVORABLE FOR
ORGANIZED/SUPERCELL STORMS...WHEREAS THE LOW-MIDLEVEL LAPSE RATES
WILL BE SUFFICIENT FOR SOME RISK OF HAIL AND STRONG WIND GUSTS WITH
A FEW STORMS THIS AFTERNOON/EVENING.

..THOMPSON/HURLBUT.. 05/12/2012

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