SPC AC 040522
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1222 AM CDT MON SEP 04 2006
VALID 041200Z - 051200Z
...THERE IS A SLGT RISK OF SVR TSTMS THIS AFTERNOON AND EVENING OVER
FAR ERN IA...SRN WI AND NRN IL...
...SYNOPSIS...
AMPLIFIED LARGE-SCALE PATTERN WILL CONTINUE THROUGH THE DAY ONE
PERIOD AS MID AND UPPER-LEVEL LOW /NOW OVER IA/ CONTINUES SEWD INTO
THE OH VALLEY AND UPSTREAM RIDGE INTENSIFIES FROM THE SWRN DESERTS
INTO ALBERTA. IN THE LOW-LEVELS...WEAK SURFACE REFLECTION OF UPPER
LOW WILL DEVELOP SEWD ACROSS ERN IA INTO WRN IL DURING THE AFTERNOON
AND EVENING HOURS WITH TRAILING FRONTAL BOUNDARY EXTENDING SWWD INTO
THE ARKLATEX. MEANWHILE TO THE E...A SECONDARY BAROCLINIC ZONE WILL
EXIST FROM THE CNTRL/ERN GULF COAST NEWD TO A WEAK INFLECTION POINT
OVER ERN TN AND THEN EWD ACROSS NC.
...FAR ERN IA/NRN IL/SRN WI...
SIMILAR TO SUNDAY OVER WRN IA...A CONCENTRATED CLUSTER OF TSTMS IS
FORECAST TO DEVELOP INVOF SURFACE AND UPPER LOWS THIS AFTERNOON
WITHIN ENVIRONMENT CHARACTERIZED BY STEEP LOW TO MID-LEVEL LAPSE
RATES AND RESULTANT SBCAPES OF 500-1000 J/KG. PRIMARY BELT OF
STRONGER MID AND UPPER TROPOSPHERIC FLOW ASSOCIATED WITH THIS LOW
ARE EXPECTED TO REMAIN DISPLACED TO THE S ACROSS SRN IL INTO CNTRL
IND...WITH EFFECTIVE BULK SHEARS OF GENERALLY 20-30 KTS ACROSS AXIS
OF STRONGEST INSTABILITY. DESPITE THE MODEST INSTABILITY AND
SHEAR...THE STRONGEST STORMS WILL BE CAPABLE OF SEVERE HAIL GIVEN
THE STEEP LAPSE RATES AND COOL THERMODYNAMIC PROFILES. ACTIVITY
SHOULD TEND TO WEAKEN BY 01-02Z AS BOUNDARY LAYER COOLS AND
STABILIZES.
...CO FRONT RANGE...
INCREASING LOW-LEVEL ELY WIND COMPONENT WILL RESULT IN VERTICAL
SHEAR PROFILES BECOMING SUPPORTIVE OF ORGANIZED/ROTATING STORMS
LATER TODAY. PRIMARY UNCERTAINTY IS WHETHER DEEP...MOIST CONVECTION
WILL INITIATE AND BECOME SUSTAINED. CURRENT WATER VAPOR IMAGERY
INDICATES A SHORT WAVE TROUGH ROTATING SWD AROUND IA UPPER LOW
ACROSS NERN WY...WITH LATEST SHORT TERM MODEL GUIDANCE MOVING THIS
FEATURE GENERALLY SWD ACROSS ERN CO TODAY. THE BOUNDARY LAYER IS
NOT EXPECTED TO BECOME PARTICULARLY WARM...THOUGH THE PRESENCE OF
MODEST LOW-LEVEL MOISTURE /DEWPOINTS IN THE MID 40S TO LOW 50S/
COUPLED WITH STEEP LOW TO MID-LEVEL LAPSE RATES WILL CONTRIBUTE TO
POCKETS OF INSTABILITY WITH SBCAPES OF 500-700 J/KG.
FORCING FOR ASCENT ASSOCIATED WITH THE SHORT WAVE TROUGH ALONG WITH
THE SUSTAINED UPSLOPE FLOW MAY BE SUFFICIENT TO INITIATE A FEW
STORMS THIS AFTERNOON OR EVENING IN THE IMMEDIATE LEE OF THE HIGHER
TERRAIN. THE STRONGEST STORMS WILL BE CAPABLE OF SOME SEVERE HAIL
AND LOCALLY GUSTY WINDS.
...SRN/CNTRL APPALACHIANS...
LATEST MODEL GUIDANCE SUGGESTS THAT A WEAK...LOWER LATITUDE IMPULSE
WILL TRANSLATE NEWD THROUGH THE MID SOUTH TOWARD THE REGION
TODAY...LIKELY FOCUSING CONCENTRATED TSTM DEVELOPMENT ALONG SW-NE
ORIENTED LOW-LEVEL FRONTAL ZONE. LAPSE RATES ARE NOT EXPECTED TO
BECOME PARTICULARLY STEEP...THOUGH THE PRESENCE OF A MOIST BOUNDARY
LAYER WILL CONTRIBUTE TO POCKETS OF INSTABILITY WITH SBCAPES OF
500-1000 J/KG. SOME INCREASE IN MID-LEVEL FLOW WILL ACCOMPANY THIS
TROUGH...WITH VERTICAL SHEAR BECOMING MARGINALLY SUPPORTIVE OF A FEW
ORGANIZED STORMS CAPABLE OF MAINLY WET MICROBURSTS.
..MEAD/GRAMS.. 09/04/2006
CLICK TO GET WUUS01 PTSDY1 PRODUCT
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1300Z
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