SWODY1
SPC AC 130529
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1129 PM CST SAT MAR 12 2011
VALID 131200Z - 141200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
WHILE AN UPPER TROUGH IS PROGGED TO SHIFT SLOWLY EWD ACROSS THE
GREAT LAKES/NERN CONUS...TWO OTHER TROUGHS -- ONE CROSSING THE
CENTRAL U.S. AND THE OTHER/LARGER ONE SHIFTING ONSHORE OVER THE PAC
NW -- WILL BE ASSOCIATED WITH TWO AREAS OF CONVECTIVE POTENTIAL THIS
PERIOD.
A COLD FRONT IS FORECAST TO MOVE ONSHORE AND CROSS WA/OREGON AND
MUCH OF CA...AS THE LARGE UPPER TROUGH SHIFTS ONSHORE.
MEANWHILE...A WEAKER/BROAD LOW PRESSURE AREA WILL AFFECT THE SRN
PLAINS -- EVOLVING ALONG THE WRN FRINGE OF THE ERN US FRONT STILL
TRAILING WWD ACROSS THE CAROLINAS/MID SOUTH/LOWER MS VALLEY AND INTO
TX DURING THE AFTERNOON.
...CENTRAL TX/ERN OK/SERN KS EWD INTO THE MID MS/TN VALLEYS...
STRENGTHENING LOW-LEVEL WARM ADVECTION BENEATH FALLING MID-LEVEL
HEIGHTS ASSOCIATED WITH THE APPROACHING SHORT-WAVE TROUGH WILL
PROVIDE INCREASING LARGE-SCALE ASCENT FOR S CENTRAL PORTIONS OF THE
U.S. THIS PERIOD. WHILE INSTABILITY WILL REMAIN GENERALLY
WEAK...COOLING MID-LEVEL TEMPERATURES/STEEPENING LAPSE RATES ATOP
LOW-LEVEL WARMING/MOISTENING WILL BE SUFFICIENT FOR SHOWER/SCATTERED
THUNDERSTORM DEVELOPMENT -- MAINLY DURING THE SECOND HALF OF THE
PERIOD. ATTM...IT APPEARS THAT RELATIVELY MEAGER INSTABILITY AND
ONLY MODERATE FLOW FIELD SHOULD PRECLUDE ANY APPRECIABLE SEVERE
THREAT.
...COASTAL WA AND OREGON AND COASTAL NW CA...
CONVECTION WILL INCREASE -- PARTICULARLY IN THE POST-FRONTAL UPSLOPE
FLOW REGIME...AS THE UPPER TROUGH SHIFTS ONSHORE YIELDING STEEPENING
MID-LEVEL LAPSE RATES. WHILE INSTABILITY WILL REMAIN LIMITED...A
FEW LIGHTNING STRIKES APPEAR POSSIBLE AT TIMES THROUGH THE
PERIOD...WITHIN A LARGER AREA OF SHOWER ACTIVITY FOCUSED ALONG
WINDWARD SIDES OF THE HIGHER TERRAIN.
..GOSS.. 03/13/2011
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