[SWODY1] SWODY1

[Severe Weather Outlook Day 1]

ACUS01 KWNS 180548
SWODY1
SPC AC 180546

DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
1246 AM CDT SUN JUN 18 2006

VALID 181200Z - 191200Z

...THERE IS A SLGT RISK OF SVR TSTMS FROM THE CNTRL GREAT LAKES SWD
INTO THE PARTS OF THE LOWER MS VALLEY...

...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF NEB AND IA...

...SYNOPSIS...

ACTIVE LARGE-SCALE PATTERN WILL CONTINUE THROUGH THE DAY ONE PERIOD
AS GREAT PLAINS TROUGH WEAKENS AND IS GRADUALLY ABSORBED INTO
INTENSIFYING NRN STREAM TROUGH FROM HUDSON BAY INTO THE GREAT LAKES.
 WITHIN THIS REGIME...VORTICITY MAXIMUM CURRENTLY OVER AR WILL
RAPIDLY LIFT NNEWD INTO THE MIDDLE OH VALLEY/S-CNTRL GREAT LAKES BY
AFTERNOON...WHILE STRONGER IMPULSE NOW OVER ERN NEB/KS SHIFTS ESEWD
TOWARD THE CONFLUENCE OF THE OH AND MS RIVERS BY LATE AFTERNOON. 
MEANWHILE IN THE W...EVOLVING TROUGH OFF THE BRITISH
COLUMBIA/PACIFIC NW COAST WILL AMPLIFY OVER THE PACIFIC NW LATER
TODAY INTO TONIGHT.

IN THE LOW-LEVELS...WEAK FRONTAL SYSTEM CURRENTLY FROM THE WRN GREAT
LAKES INTO MID MO VALLEY WILL SLOWLY SHIFT EWD TODAY...REACHING THE
CNTRL GREAT LAKES SWD INTO MID MS VALLEY LATER TODAY.  ELSEWHERE...A
SECONDARY...WEAK FRONT WILL PUSH SWD THROUGH THE NRN PLAINS /IN
ASSOCIATION WITH A MID-LEVEL JET STREAK MOVING OUT OF THE NRN HIGH
PLAINS/ INTO CNTRL PORTIONS OF NEB AND IA BY EARLY EVENING.

...CNTRL GREAT LAKES INTO THE LOWER MS VALLEY...

CURRENT SURFACE OBSERVATIONS INDICATE A MOIST LOW-LEVEL AIR MASS IN
PLACE FROM THE LOWER MS VALLEY NWD INTO THE LOWER OH VALLEY WITH
DEWPOINTS IN THE MID 60S TO LOWER 70S. SSWLY LLJ WILL BE MAINTAINED
THROUGH THE PERIOD ACROSS THE REGION SUPPORTING NWD ADVECTION OF
THIS RICHER MOISTURE INTO THE CNTRL GREAT LAKES.  WHILE LAPSE RATES
ARE NOT EXPECTED TO BE PARTICULARLY STEEP...DAYTIME HEATING COUPLED
WITH THIS MOISTURE ARE EXPECTED TO CONTRIBUTE TO SBCAPES OF
1000-2000 J/KG OVER THE LOWER MS VALLEY...TO 500-1000 J/KG OVER THE
SRN GREAT LAKES.

WHILE TSTMS ARE EXPECTED TO BE FAIRLY WIDESPREAD TODAY WITHIN THIS
MOIST...DEEP SWLY FLOW...LATEST SHORT TERM MODEL GUIDANCE SUGGESTS
THE POTENTIAL FOR MORE CONCENTRATED SEVERE WEATHER OVER TWO AREAS: 
IND/WRN OH INTO LOWER MI AND FROM THE CONFLUENCE OF THE OH/MS RIVERS
SWD INTO NRN PARTS OF THE LOWER MS VALLEY.

VORTICITY MAXIMUM NOW OVER AR IS FORECAST TO RAPIDLY LIFT
NNEWD...REACHING IND/WRN OH/LOWER MI BY THIS AFTERNOON WITH AN
ASSOCIATED BELT OF 45-55 KTS MID-LEVEL WINDS OVERSPREADING REGION. 
WHILE THERMODYNAMIC PROFILES WILL BE QUITE MOIST WITH MODEST
INSTABILITY...FORCING FOR ASCENT ASSOCIATED WITH THIS IMPULSE WILL
LIKELY FOCUS A CONCENTRATED CLUSTER OF STORMS AHEAD OF EWD-MOVING
FRONTAL ZONE WITH THE POTENTIAL FOR DAMAGING WINDS AND PERHAPS A
TORNADO OR TWO.

FARTHER S...A SECONDARY CLUSTER OF STRONG/SEVERE STORMS IS EXPECTED
TO DEVELOP BY AFTERNOON NEAR THE CONFLUENCE OF THE OH AND MS RIVERS
IN ADVANCE OF STRONGER IMPULSE MOVING THROUGH MO/NRN AR.  WHILE WIND
FIELDS WILL BE WEAKER THAN POINTS TO THE N...INSTABILITY IS FORECAST
TO BE STRONGER...SUPPORTING ORGANIZED STORMS CAPABLE OF SEVERE HAIL
AND DAMAGING WIND GUSTS.

...NEB/IA...

ONLY MARGINAL LOW-LEVEL MOISTURE /I.E. 50-55 F DEWPOINTS/ IS
FORECAST TODAY ACROSS DISCUSSION AREA AHEAD OF WEAK FRONT SHIFTING
SWD OUT OF SD/SRN MN.  HOWEVER...ANTICIPATED STRONG DIABATIC HEATING
WILL RESULT IN THE DEVELOPMENT OF STEEP LOW-LEVEL LAPSE
RATES...CONTRIBUTING TO SBCAPES OF AROUND 1000 J/KG.  SURFACE-BASED
TSTMS WILL BECOME INCREASINGLY LIKELY BY LATE AFTERNOON ALONG NWRN
EDGE OF INSTABILITY AXIS OVER SRN SD OR NRN NEB AS 50 KT MID-LEVEL
JET STREAK AND ASSOCIATED LOW AMPLITUDE SHORT WAVE TROUGH APPROACH
FROM THE NW.  STORMS SHOULD INCREASE IN COVERAGE AND INTENSITY AS
THEY MOVE/DEVELOP SEWD THROUGH ERN NEB INTO WRN AND CNTRL IA THIS
EVENING INTO TONIGHT.

FORECAST WIND PROFILES INDICATE LARGELY UNIDIRECTIONAL 40-50 KT
DEEP-LAYER SHEAR...SUPPORTIVE OF ORGANIZED STORMS INCLUDING
SUPERCELLS.  GIVEN THE ANTICIPATED...WELL-MIXED BOUNDARY LAYER
CONDITIONS...DAMAGING WINDS APPEAR TO BE THE PRIMARY SEVERE WEATHER
HAZARD...THOUGH THE STRONGEST STORMS WILL ALSO BE CAPABLE OF SEVERE
HAIL.  THIS CONVECTIVE ACTIVITY SHOULD CONTINUE INTO CNTRL/SRN IA
TONIGHT PRIOR TO WEAKENING AS THE AIR MASS SLOWLY COOLS AND
STABILIZES.

..MEAD/TAYLOR.. 06/18/2006