SPC AC 160531
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1131 PM CST TUE FEB 15 2011
VALID 161200Z - 171200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
STRONG HEIGHT FALLS WITH A LARGE UPPER TROUGH WILL AFFECT THE W
COAST EARLY WED...AND WILL CONTINUE EWD ACROSS THE GREAT BASIN
THROUGH 00Z. AT THE SURFACE...A PRE-FRONTAL TROUGH WILL EXTEND FROM
THE ID/ORE BORDER SWWD TO THE NRN CA COAST AT 12Z...AND WILL MOVE
RAPIDLY EWD WITH A DEVELOPING COLD FRONT INTO ERN NV/WRN UT BY LATE
AFTERNOON/EVENING. MEANWHILE...ADDITIONAL THUNDERSTORMS ARE LIKELY
ACROSS CNTRL/NRN CA...WITH POCKETS OF DESTABILIZATION AND VERY STEEP
MID LEVEL LAPSE RATES BENEATH AN UPPER THERMAL TROUGH.
...W COAST INTO THE SAN JOAQUIN AND SACRAMENTO VALLEYS...
SCATTERED SHOWERS AND STORMS WILL LIKELY BE ONGOING ALONG A COLD
FRONT FROM NRN CA NWD ALONG THE ORE/WA COAST EARLY WED...AND WILL
SHIFT EWD ACROSS THE SIERRA DURING THE DAY. SEVERE WEATHER APPEARS
UNLIKELY WITH THIS EARLY ACTIVITY AS LOW LEVEL WINDS VEER WITH THE
FRONTAL SURGE...AND BEFORE STEEPER LAPSE RATES ARRIVE.
HOWEVER...AREAS OF DAYTIME HEATING AND PERSISTENTLY COLD AIR ALOFT
WITH 500 MB TEMPERATURES ON THE ORDER OF -30 TO -35 C WILL FAVOR
DEEPENING SHOWERS AND THUNDERSTORMS BY AFTERNOON. ALSO BY
AFTERNOON...LOW LEVEL WINDS WILL TEND TO BACK ACROSS THE
VALLEYS...RESULTING IN LOW MAGNITUDE BUT VEERING PROFILES WHICH MAY
BE FAVORABLE FOR A FEW ROTATION STORMS. AS SUCH...HAVE INTRODUCED A
2% TORNADO PROBABILITY FOR ONE OR TWO BRIEF/WEAK TORNADOES WITH THE
DAYTIME CONVECTION. IN ADDITION...SMALL...SUB-SEVERE HAIL IS LIKELY.
...NV INTO WRN UT...
AS THE COLD FRONT PASSES OVER THE SIERRA...CONVERGENCE WILL INCREASE
OVER CNTRL/ERN NV...RESULTING IN A STRONGLY FORCED LINE OF SHOWERS
AND EMBEDDED THUNDERSTORMS. MOISTURE AND INSTABILITY FOR CONVECTION
WILL BE MEAGER AHEAD OF THE FRONT...BUT STRONG COOLING ALOFT
COMBINED WITH DEEP LAYER FORCING FOR ASCENT MAY RESULT IN A FEW
HIGHER REFLECTIVITY CORES OR LINEAR STRUCTURES ALONG THE
FRONT...WITH POTENTIAL FOR ENHANCED WIND GUSTS VIA DOWNWARD MIXING.
..JEWELL/GARNER.. 02/16/2011
CLICK TO GET WUUS01 PTSDY1 PRODUCT
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1300Z
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