SPC AC 211658
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1058 AM CST WED JAN 21 2009
VALID 221200Z - 231200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
THE CURRENT PATTERN CONSISTING OF A BROAD UPPER TROUGH OVER THE ERN
U.S. WITH A RIDGE CENTERED OVER THE ROCKIES WILL BREAK DOWN INTO A
MORE ZONAL PROGRESSIVE REGIME BY THURSDAY. SHORTWAVE TROUGH OVER THE
ERN PACIFIC WILL DEAMPLIFY AS IT UNDERCUTS UPPER RIDGE AND MOVES
THROUGH CA AND INTO THE SWRN STATES.
...SRN CA THROUGH SRN AZ...
WV IMAGERY SHOWS A PLUME OF SUBTROPICAL MID-UPPER LEVEL MOISTURE
WITHIN GRADIENT ZONE BETWEEN UPPER TROUGH OFF THE CA COAST AND
RETREATING UPPER RIDGE. A SERIES OF WEAK IMPULSES WILL CONTINUE TO
LIFT NWD WITHIN THIS REGIME IN ADVANCE OF PRIMARY UPPER TROUGH
THURSDAY. OWING TO LIMITED BOUNDARY LAYER MOISTURE...INSTABILITY
WILL REMAIN WEAK AND CONFINED TO MAINLY TO THE 700-400 MB LAYER
WHERE MODEST 6.5-7 C/KM LAPSE RATES WILL EXIST. MID LEVEL ASCENT
RESULTING FROM THE NEWD EJECTING IMPULSES WILL CONTRIBUTE TO PERIODS
OF MOSTLY ELEVATED CONVECTION OVER THE AZ. HOWEVER...THE MARGINAL
THERMODYNAMIC PROFILES SUGGEST ANY LIGHTNING ACTIVITY WILL PROBABLY
REMAIN AOB 10% COVERAGE.
OTHER CONVECTION WILL LIKELY DEVELOP ACROSS SRN CA AND EVENTUALLY
INTO SRN AZ WITHIN ZONE OF LIFT AND DPVA ASSOCIATED WITH VORT MAX
EMBEDDED WITHIN BASE OF PRIMARY UPPER TROUGH. WEAK BUOYANCY IN THE
700-400 MB LAYER SHOULD LIMIT LIGHTNING COVERAGE TO AOB 10%.
..DIAL.. 01/21/2009
CLICK TO GET WUUS02 PTSDY2 PRODUCT
NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 0700Z
|
