SWODY1
SPC AC 221252
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0752 AM CDT SUN MAR 22 2009
VALID 221300Z - 231200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
JET STREAK NOW MOVING SSE OFF THE NRN CA CST EXPECTED TO FURTHER
AMPLIFY ALREADY-POTENT CNTRL CA TROUGH. THE TROUGH SHOULD MOVE E
ACROSS THE SRN GRT BASIN TODAY...BEFORE TURNING NEWD INTO ERN CO
EARLY MON AS A CLOSED LOW. AHEAD OF THE MAIN TROUGH...A MORE
LOOSELY ORGANIZED BAND OF ASCENT...NOW EXTENDING FROM CNTRL MT
THROUGH CNTRL WY INTO WRN CO...SHOULD CONTINUE ENE INTO THE PLNS
LATER TODAY...AND INTO THE UPR MS/LWR MO VLYS TONIGHT/EARLY MON.
AT THE SFC...EXPECT SFC LOW NOW OVER SE MT WILL REFORM SWD INTO NE
CO BY THIS EVE AS LEE TROUGH BECOMES BETTER DEFINED OVER THE
CNTRL/SRN HI PLNS. COLD FRONT DIRECTLY ASSOCIATED WITH CA TROUGH
WILL MOVE E ACROSS THE GRT BASIN TODAY AND OVERTAKE NRN PART OF THE
LEE TROUGH EARLY MON...WHILE SHALLOWER COLD SURGE NOSES SSE ACROSS
THE NRN HI PLNS. FARTHER E...WARM/STNRY FRONT SHOULD EVOLVE WITH
TIME FROM ERN SD SE INTO THE LWR MO/MID MS VLYS.
...GRT PLNS...
CURRENT SATELLITE AND SFC DATA CONTINUE TO SHOW THAT MOISTURE WILL
REMAIN RELATIVELY LIMITED OVER THE PLNS STATES THIS PERIOD...DESPITE
EXPECTED STRENGTHENING/BROADENING OF SSWLY LOW LVL FLOW E OF LEE
TROUGH/DRY LINE. SFC DEWPOINTS SHOULD REMAIN MOSTLY AOB 50 F OVER
NRN PORTIONS OF THE PLNS...WITH POCKETS OF LOW TO MID 50S POSSIBLE
OVER CNTRL/SRN SECTIONS. AT THE SAME TIME...CLDS ASSOCIATED WITH
LEAD UPR IMPULSE WILL DIMINISH SFC HEATING IN MANY AREAS. AS A
RESULT...OVERALL DESTABILIZATION SHOULD REMAIN MODEST...WITH MLCAPE
REMAINING AOB 500-1000 J/KG.
DESPITE THE ABOVE LIMITATIONS...SEVERAL AREAS/SCENARIOS WILL REQUIRE
MONITORING FOR LOCALIZED/LIMITED SVR POTENTIAL. THESE INCLUDE:
1. CNTRL/SRN NEB AND WRN/CNTRL KS SW INTO WRN OK/TX PANHANDLE THIS
AFTN/EVE...WHERE FORCING ASSOCIATED WITH LEAD UPR IMPULSE...AND SFC
HEATING...MAY SUPPORT WDLY SCTD LATE AFTN/EVE STORMS ALONG LEE
TROUGH/DRY LINE SEGMENTS. DEEP WSWLY SHEAR WILL INCREASE WITH TIME
AS GRT BASIN UPR SYSTEM...AND DIRECTIONAL COMPONENT WILL BE
FAVORABLE FOR SUSTAINED ROTATING STORMS /ESPECIALLY OVER SRN
SECTIONS/. SVR HAIL AND LOCALLY DMG WIND GUSTS MAY OCCUR. BUT
COMBINATION EML CAP AND MODEST MOISTURE SUPPLY SHOULD LIMIT OVERALL
SVR INTENSITY/DURATION. SOME OF THIS ACTIVITY MAY EVOLVE INTO SMALL
CLUSTERS OR BANDS THAT CONTINUE E ACROSS KS AND NRN OK TNGT.
2. NE OF DEVELOPING WARM FRONT...CLUSTERS OF ELEVATED STORMS
EXPECTED TO PERSIST OVER ND TODAY...AND EXPAND SSE INTO ERN
SD/MN/IA/ERN NEB AND NRN MO LATER TODAY THROUGH EARLY MON. WITH
MUCAPE INCREASING TO 750 OR PERHAPS 1000 J/KG IN EXIT REGION OF
40-50 KT LLJ...SOME STORMS ROOTED ABOVE FRONTAL SURFACE MAY YIELD
SVR HAIL. CLOUD-LYR SHEAR SHOULD...HOWEVER...REMAIN COMPARATIVELY
WEAK AND LIMIT STORM LONGEVITY/ORGANIZATION. ON THE SW EDGE OF THIS
ACTIVITY IN ERN NEB...A SMALL WINDOW OF OPPORTUNITY WILL EXIST FOR
SFC-BASED STORMS LATE THIS AFTN/EARLY TNGT...IF HEATING AND LOW LVL
CONVERGENCE VERIFY STRONGER THAN NOW EXPECTED. WIND PROFILES IN THE
REGION COULD SUPPORT SUPERCELLS GIVEN A SUSTAINED UPDRAFT...AND AN
ATTENDANT THREAT FOR SVR HAIL/WIND.
3 OVER THE CNTRL HI PLNS EARLY MON...EXPECT STORMS TO FORM ON
LEADING EDGE OF STRONG ASCENT/DPVA ASSOCIATED WITH GRT BASIN TROUGH.
COMBINATION OF ASSOCIATED DESTABILIZATION ALOFT...LOW LVL
CONVERGENCE N-NE OF DEEPENING NE CO SFC LOW...AND FRONTOGENETIC
FORCING MAY SUPPORT A LINE OF STRONG TO POSSIBLY SVR STORMS LATE IN
THE PERIOD OVER SW SD AND WRN/NRN NEB SE INTO NW KS. STEEPENING MID
LVL LAPSE RATES WILL BOOST MUCAPE TO AOA
1000 J/KG...ALTHOUGH TEMPORAL BACKING OF LOW TO MID TROPOSPHERIC
FLOW SUGGESTS STORMS WILL QUICKLY ASSUME A LINEAR ORGANIZATION.
ATTM IT APPEARS THAT GREATEST BLOSSOMING OF STORMS WILL OCCUR JUST
AFTER 12Z. BUT IF IT APPEARS THAT GRT BASIN VORT WILL PROGRESS MORE
RAPIDLY THAN NOW EXPECTED...A CATEGORICAL SLIGHT RISK MAY BE
REQUIRED IN LATER OUTLOOK.
..CORFIDI/SMITH.. 03/22/2009
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