SWODY1
SPC AC 141249
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0649 AM CST MON DEC 14 2009
VALID 141300Z - 151200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
A TWO-STREAM...LOW AMPLITUDE PATTERN WILL PREVAIL OVER THE LWR 48
THIS PERIOD...POLEWARD OF PERSISTENT ELONGATED RIDGE OVER THE ERN
GULF OF MEXICO/WRN ATLANTIC. SHORTWAVE TROUGH NOW OVER THE LWR MO
VLY SHOULD SHEAR ENE TO THE LWR GRT LKS LATER TODAY/TONIGHT AS
STRONGER UPSTREAM DISTURBANCE MOVES ESE FROM THE CANADIAN RCKYS.
OVERALL SETUP WILL SERVE TO MAINTAIN/TEMPORARILY STRENGTHEN DEEP WSW
FLOW OVER THE SERN QUARTER OF THE U.S.
AT LWR LVLS...SHALLOW ARCTIC COLD FRONT ASSOCIATED WITH MO VLY
TROUGH WILL CONTINUE STEADILY SE ACROSS THE MS AND OH VLYS...THE
OZARKS...THE SRN PLNS...AND THE NWRN GULF OF MEXICO THROUGH EARLY
TUE. AT THE SAME TIME...OLD FRONTAL ZONE STALLED ALONG THE GULF CST
LIKELY WILL BEGIN TO DRIFT NWD TODAY IN RESPONSE TO FALLING
PRESSURES AHEAD OF ARCTIC COLD FRONT. THE GULF FRONT WILL TEND TO
WEAKEN AS THE LOW LVL FLOW OVER THE REGION BECOMES LARGELY
FRONTOLYTIC. CONVECTIVE OUTFLOW WILL...HOWEVER...LIKELY SERVE TO
REINFORCE PARTS OF THE BOUNDARY AS STORMS FORM ALONG IT LATER
TODAY/TONIGHT.
...CNTRL/ERN GULF CST...
CONTINUED EWD MOTION OF MO VLY SHORTWAVE IMPULSE WILL
MAINTAIN/TEMPORARILY STRENGTHEN WSWLY LLJ OVER THE LWR MS VLY/GULF
CST REGION TODAY/TONIGHT. PERSISTENT WAA AND MOISTURE TRANSPORT
SHOULD SUPPORT DEVELOPMENT OF AN ARC OF DEEP CONVECTION/STORMS ALONG
THE CONFLUENT PART OF JET...FROM THE NWRN GULF OF MEXICO ENE ALONG
THE CNTRL GULF CST INTO SRN AL/GA...BY MIDDAY.
COMBINATION OF DEEP/LARGELY UNIDIRECTIONAL FLOW...AND APPRECIABLE
MOISTURE /PW INCREASING TO A0A 1.75 INCHES/...LIKELY WILL FOSTER
EPISODES OF REGENERATIVE/BACK-BUILDING ACTIVITY THIS AFTN THROUGH
EARLY TUE. WSWLY CLOUD LAYER SHEAR WILL REMAIN FAIRLY MODEST AT
30-40 KTS. BUT THE ENVIRONMENT MAY SUPPORT A FEW CLUSTERS WITH
EMBEDDED SUSTAINED STORMS...ESPECIALLY ALONG THE CNTRL GULF CST THIS
AFTN/EVE...WHERE SBCAPE COULD APPROACH 1000 J/KG. THE STORMS MAY
YIELD ISOLD DMGG WIND GUSTS/WET MICROBURSTS...AND POSSIBLY A
TORNADO. WEAK MID LVL LAPSE RATES AND ABSENCE OF SUBSTANTIAL UPR
DIVERGENCE/ASCENT SHOULD...HOWEVER...KEEP OVERALL SVR THREAT
MARGINAL.
RENEWED/ADDITIONAL STORM DEVELOPMENT MAY OCCUR LATE IN THE PERIOD
OVER THE NWRN GULF/SRN LA AS ARCTIC BOUNDARY ENTERS REGION AND
UNDERCUTS PERSISTENT LOW LVL WSWLY CURRENT OF WARM/MOIST AIR.
..CORFIDI.. 12/14/2009
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