[SWODY1] SWODY1

[Severe Weather Outlook Day 1]

ACUS01 KWNS 021635
SWODY1
SPC AC 021634

DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
1134 AM CDT SUN APR 02 2006

VALID 021630Z - 031200Z

...THERE IS A MDT RISK OF SVR TSTMS PORTIONS CENTRAL/ERN
MO...SRN/WRN IL...EXTREME SERN IA...EXTREME NERN AR...EXTREME NWRN
TN...WRN KY....

...THERE IS A SLGT RISK OF SVR TSTMS ELSEWHERE FROM E TX TO WRN NC
TO OH/SRN LOWER MI TO SERN NEB....

...SYNOPSIS...
PROGRESSIVE SHORTWAVE PATTERN ALOFT WILL FEATURE TWO-WAVE SYSTEM NOW
CAUSING HEIGHT FALLS ACROSS MID/UPPER MS VALLEY REGION.  INITIAL
TROUGH OVER CENTRAL KS AND OK IS EXPECTED TO ACCELERATE EWD THEN
NEWD ACROSS MO/IL/IA THROUGH 3/00Z...THEN WEAKEN THEREAFTER ACROSS
PORTIONS INDIANA/LM/LOWER MI.  MEANWHILE UPSTREAM SHORTWAVE TROUGH
-- NOW EVIDENT IN MOISTURE CHANNEL IMAGERY OVER WRN NEB/NERN CO/SERN
WY -- WILL DIG SEWD ACROSS KS. EXPECT THIS FEATURE TO BECOME
DOMINANT PERTURBATION AS IT PIVOTS EWD OVER MID MS VALLEY
OVERNIGHT...REACHING FROM SRN LOWER MI TO WRN TN BY END OF PERIOD.

AT SFC..CYCLONE OVER SERN NEB SHOULD MOVE ENEWD ACROSS ERN
IA..DEEPENING/OCCLUDING TONIGHT AS IT APCHS/CROSSES SRN LM. 
ASSOCIATED COLD FRONT WILL MOVE SWD/SEWD ACROSS MUCH OF MO...OK AND
SRN HIGH PLAINS...CATCHING UP WITH DRYLINE INITIALLY ANALYZED FROM
SERN KS INTO SWRN OK.  WARM FRONT -- ANALYZED AT 15Z FROM SERN NEB
EWD ACROSS NERN MO...THEN SEWD OVER EXTREME SRN IL AND EXTREME WRN
KY -- IS FCST TO LIFT NEWD ACROSS REMAINDER MO...MOST OF IL/KY AND
PORTIONS SRN INDIANA THROUGH 3/00Z.  ILL-DEFINED OUTFLOW BOUNDARY IS
EVIDENT FROM E-CENTRAL AND CENTRAL AR NWWD ACROSS SWRN MO AND SWRN
KS...AND SHOULD WEAKEN WITH TIME.

...E-CENTRAL PLAINS TO SRN GREAT LAKES AND OH VALLEY...
SOME SEVERE POTENTIAL EXISTS AS INITIALLY ELEVATED TSTMS OVER
N-CENTRAL/NERN KS AND SERN NEB MOVE EWD INTO DESTABILIZING LOW LEVEL
ENVIRONMENT.  OPTIMALLY STEEP MIDLEVEL LAPSE RATES ARE EVIDENT ATTM
OVER PORTIONS NERN KS/SERN NEB...IN ZONE OF STRONGEST MIDLEVEL
DPVA...AHEAD OF COLD-CORE LOW. REF SPC MESOSCALE DISCUSSION 400 FOR
NEAR-TERM FCST DETAILS.

THIS ACTIVITY AND/OR ADDITIONAL DEVELOPMENT OVER MO VALLEY REGION
SHOULD MOVE EWD ACROSS MO INTO IL...AMIDST INCREASINGLY FAVORABLE
DEEP-LAYER INSTABILITY.  CONVECTIVELY STABILIZED BOUNDARY LAYER AIR
MASS IS EVIDENT BETWEEN DIFFUSE OUTFLOW BOUNDARY AND WARM
FRONT...WHICH WILL TEMPORARILY SUPPRESS SFC-BASED SEVERE POTENTIAL. 
EXPECT MOIST ADVECTION TO OFFSET VERTICAL MIXING WITHIN BOUNDARY
LAYER AS MOISTURE RECOVERS OVER THIS REGION THROUGH MID-AFTERNOON. 
THIS SHOULD RESULT IN LOW-MID 60S F SFC DEW POINTS SPREADING NEWD
FROM NERN OK/SERN KS/NRN AR REGION...ACROSS MORE OF MO THROUGH
MID-LATE AFTERNOON.  AS THIS OCCURS...SFC AIR MASS WILL DESTABILIZE
CONSIDERABLY IN TUNE WITH STEEPENING MIDLEVEL LAPSE RATES.

SHEAR PROFILES BY MID/LATE AFTERNOON AND EARLY EVENING WILL SUPPORT
BOTH SUPERCELL AND BOW ECHO STRUCTURES...AND MIXED CONVECTIVE MODE
IS EXPECTED.  STRONG PRIMARY ARC OF ASCENT -- EXPECTED TO MOVE EWD
ACROSS MO/SRN IA/IL -- SHOULD LEAD TO SOME LINEAR SEGMENTS WITH
TIME.  HOWEVER...DISCRETE SUPERCELLS ALSO ARE POSSIBLE BOTH EARLY IN
EVOLUTION OF MAIN BAND AND FARTHER E IN WARM SECTOR.  DAMAGING
HAIL/GUSTS AND TORNADOES ALL ARE POSSIBLE...WITH SIGNIFICANT-TORNADO
PROBABILITIES GREATEST INVOF WARM FRONT WHERE LOW LEVEL HODOGRAPHS
AND DEEP-LAYER BULK SHEAR SHOULD BE MAXIMIZED.

ACTIVITY SHOULD CONSOLIDATE INTO ONE OR MORE QUASI-LINEAR MCS
OVERNIGHT...MOVING ENEWD ACROSS OH VALLEY AND SRN GREAT LAKES
REGIONS.  MAIN THREAT SHOULD BE DAMAGING WIND AND OCCASIONAL
HAIL...THOUGH VERTICAL SHEAR PROFILES STILL WILL BE FAVORABLE FOR A
FEW TORNADOES.

...ARKLATEX REGION...E TX...LOWER MS VALLEY...
REF WW 129 AND RELATED MESOSCALE DISCUSSIONS FOR NOWCAST SITUATION
OVER PORTIONS CENTRAL/E TX.

LATER THIS AFTERNOON...DECREASING CONVERGENCE IS EXPECTED WITH SWD
EXTENT ACROSS OZARKS INTO ARKLATEX REGION AND NRN MS...AND WITH TIME
OVER SAME REGION.  THIS IS RELATED TO WEAKENING SFC WINDS AND SWLY
FLOW IN MOIST LAYER.  HOWEVER...WEAK CAPPING HAS ALLOWED DEVELOPMENT
OVER PORTIONS CENTRAL TX...WITH MORE ACTIVITY POSSIBLY ENEWD TOWARD
SRN AR/NRN LA AND EVENTUALLY NRN MS.  SEVERE POTENTIAL FROM ANY
ACTIVITY THAT DEVELOPS STILL WARRANTS CATEGORICAL SLGT RISK BECAUSE
OF FAVORABLE DEEP-LAYER SHEAR AND BOUNDARY LAYER THETAE THAT WILL BE
AVAILABLE.

..EDWARDS.. 04/02/2006