[SWODY1] SWODY1

[Severe Weather Outlook Day 1]

ACUS01 KWNS 131959
SWODY1
SPC AC 131958

DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
0258 PM CDT THU APR 13 2006

VALID 132000Z - 141200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE UPPER
MIDWEST...SRN GREAT LAKES AND OH VALLEY...

...UPPER MIDWEST/OH VALLEY...
WATER VAPOR IMAGERY AND RUC ANALYSIS CURRENTLY SHOW A SUBTLE
SHORTWAVE TROUGH EMBEDDED IN WNW FLOW OVER SRN MN EXTENDING SWWD
ACROSS FAR SE SD. THIS FEATURE IS FORECAST TO MOVE QUICKLY ESEWD
ACROSS THE REGION LATE THIS AFTERNOON INTO THIS EVENING. LARGE-SCALE
ASCENT ASSOCIATED WITH THE SHORTWAVE AND A WEAKENING CAPPING
INVERSION WILL PROVIDE SUPPORT FOR CONVECTIVE INITIATION LATE THIS
AFTERNOON ACROSS WRN WI AND ERN IA. STORMS SHOULD GRADUALLY EXPAND
IN COVERAGE WITH AN MCS DEVELOPING AND MOVING QUICKLY ESEWD ACROSS
THE REGION THIS EVENING AND OVERNIGHT.

LATEST SFC ANALYSIS CURRENTLY SHOWS A MOIST AXIS WITH SFC DEWPOINTS
IN THE 60S F EXTENDING NWD ACROSS MO INTO SRN IA. SLY FLOW WILL
CONTINUE MOIST ADVECTION INTO IA AND IL THIS AFTERNOON WITH A STRONG
LOW-LEVEL MOISTURE GRADIENT SETTING UP FROM NEAR THE DES
MOINES/CEDAR RAPIDS AREA EXTENDING ESEWD TO NEAR SPRINGFIELD IL.
ALONG AND SOUTH OF THIS GRADIENT...MODERATE INSTABILITY SHOULD BE IN
PLACE WITH MLCAPE VALUES IN THE 2000 TO 3000 J/KG RANGE BY LATE THIS
AFTERNOON AND EARLY THIS EVENING. IN ADDITION...WNWLY FLOW ALOFT IS
CREATING STRONG VERTICAL SHEAR PROFILES WHICH COMBINED WITH VERY
STEEP LAPSE RATES AND THE MODERATE INSTABILITY SHOULD BE FAVORABLE
FOR SUPERCELLS WITH LARGE HAIL. THE STRONGER SUPERCELLS MAY ALSO BE
CAPABLE OF PRODUCING VERY LARGE HAIL ESPECIALLY ACROSS CNTRL/ERN IA
AND NW IL LATE THIS AFTERNOON WHEN INSTABILITY SHOULD BE MAXIMIZED.
IN ADDITION...MODELS FORECAST A 50 KT LOW-LEVEL JET TO EXPAND NWD
ACROSS THE REGION WHICH WILL CREATE STRONG LOW-LEVEL SHEAR PROFILES
WHICH COMBINED WITH THE MOISTURE ADVECTION SHOULD RESULT IN A
TORNADO/WIND DAMAGE THREAT AS SUPERCELLS MOVE ESEWD ACROSS ERN IA
INTO NRN AND CNTRL IL AND WRN IND THIS EVENING. IF A LARGE-SCALE BOW
ECHO DEVELOPS AS THE NAM CONVECTIVE QPF FIELDS SUGGEST...THEN THE
WIND DAMAGE POTENTIAL WOULD LIKELY BE ENHANCED CONTINUING OVERNIGHT
AS THE LINEAR MCS TRACKS ESEWD ACROSS IND...NRN KY INTO OH.

..BROYLES.. 04/13/2006