[SWODY1] SWODY1

[Severe Weather Outlook Day 1]

ACUS01 KWNS 271628
SWODY1
SPC AC 271627

DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
1127 AM CDT WED SEP 27 2006

VALID 271630Z - 281200Z

...THERE IS A SLGT RISK OF SVR TSTMS FROM THE MIDWEST SWWD ACROSS
FROM THE LWR OH VLY TO THE OZARKS...

...SYNOPSIS...
WV IMAGERY INDICATES A SERIES OF MID LEVEL IMPULSES WITHIN BROADER
TROUGH OVERSPREADING THE CENTRAL U.S. THIS MORNING.  ONE SYSTEM WILL
CONTINUE EWD ACROSS THE CENTRAL GREAT LAKES...WHILE MORE SUBTLE SRN
STREAM IMPULSE NOW SUSTAINING CONVECTION NEAR THE OZARKS IS ABSORBED
INTO BROADER TROUGH AND SPREADS EWD TOWARDS THE LOWER OH RIVER
VALLEY.  AN EVEN STRONGER SYSTEM NOW MOVING ACROSS THE SD WILL
AMPLIFY LARGER TROUGH AS IT DIGS SEWD INTO THE MID MS RIVER VALLEY
OVERNIGHT.  AT THE SURFACE...PRIMARY/LEADING COLD FRONT ASSOCIATED
WITH THE BROAD MID/UPPER TROUGH EXTENDED FROM A LOW CENTER OVER NRN
LOWER MI SSWWD INTO SWRN MO/NERN OK AT 15Z.  THIS WILL CONTINUE
ADVANCING ESEWD THROUGH THE DAY...AHEAD OF WHICH A GRADUAL INCREASE
IN SURFACE DEW POINTS WILL OCCUR WITH READINGS IN THE MID 50S-LOW
60S EXPECTED FROM SERN MO/NRN AR INTO CENTRAL IND BY LATE IN THE
DAY.

...OZARKS INTO THE SRN GREAT LAKES...
MODELS VERY CONSISTENT IN INCREASING INSTABILITY AND THE POTENTIAL
FOR DEEP MOIST CONVECTION ALONG AND JUST AHEAD OF THE SURFACE FRONT
FROM NWRN AR INTO SRN IL AROUND 21Z...WITH PRIMARY QPF BETWEEN
21Z-00Z.  FORECAST SOUNDINGS FROM THE NAM AND RUC INDICATE MLCAPE
MAY APPROACH 2000 J/KG SHOULD SURFACE DEW POINTS REACH THE LOW 60S F
NEAR PEAK HEATING INTO THE LOWER OH RIVER VALLEY.  WILL MOST LIKELY
SEE AN AXIS OF 1000-1500 J/KG MLCAPE EXTENDING FROM SWRN MO INTO
SWRN/CENTRAL IND BY 21Z...WITH A HIGHER MAX POSSIBLE NEAR THE LOWER
OH RIVER VALLEY.  MLCAPE NEARER 500 J/KG CAN BE EXPECTED INTO THE
NERN IND/NWRN OH.  MODEST TO STRONG WNWLY FLOW ALOFT WILL ALSO
SUPPORT EFFECTIVE SHEAR AROUND 40 KT...SUGGESTING A FEW SUPERCELLS
WILL BE POSSIBLE ALONG WITH AT LEAST A THREAT OF A TORNADO OR TWO. 
HOWEVER...OVERALL EVOLUTION INTO ONE OR MORE SMALL LINES/CLUSTERS IS
THE MORE LIKELY SCENARIO UNDER A NEAR-UNIFORM WLY FLOW THROUGH THE
MID LEVELS.  LARGE HAIL AND DAMAGING WINDS WILL LIKELY BE PRIMARY
SEVERE THREATS.  OVERALL SEVERE THREAT IS EXPECTED TO BECOME MORE
LIMITED WITH NEWD EXTENT TOWARDS THE SRN GREAT LAKES.

...CENTRAL PLAINS...
A SECONDARY REGION OF POSSIBLE SEVERE TSTMS WILL EVOLVE THIS
AFTERNOON FROM PARTS OF SERN SD/NEB SEWD INTO NWRN MO/WRN IA.  CORE
OF STRONGEST DCVA ASSOCD WITH APPROACHING IMPULSE WILL TRACK SEWD
ACROSS THIS REGION BETWEEN 18-00Z.  LAPSE RATES WILL STRONGLY
STEEPEN AS H5 TEMPERATURES AOB MINUS 20 DEG C SURGE SEWD ATOP
RESIDUAL 50S DEW POINTS.  IF BOUNDARY LAYER CAN HEAT...A BAND OF
LOW-TOPPED AND FAST-MOVING TSTMS WILL DEVELOP PRODUCING POSSIBLE
HAIL/STRONG WINDS.

..EVANS/CROSBIE.. 09/27/2006