The SPC is forecasting ...severe thunderstorms expected over parts of the lower mississippi valley today.... Please read the latest public statement about this event.
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SPC AC 021243
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0743 AM CDT FRI MAY 02 2008
VALID 021300Z - 031200Z
...THERE IS A MDT RISK OF SVR TSTMS TODAY FOR ERN AR...THE MO
BOOTHEEL...WRN TN...NW MS...AND EXTREME NRN LA...
...THERE IS A SLGT RISK OF SVR TSTMS SURROUNDING THE MDT RISK...FROM
THE LOWER MS VALLEY TO THE MID MS VALLEY AREA...
...SYNOPSIS...
A DEEP MID LEVEL LOW WILL MOVE SLOWLY EWD FROM THE CENTRAL PLAINS TO
THE MS VALLEY BY TONIGHT. OVERNIGHT CONVECTION HAS COMPLICATED THE
SURFACE PATTERN...WITH THE SOON-TO-BE PRIMARY SURFACE LOW DEVELOPING
NNEWD FROM WRN MO TO CENTRAL IA TODAY AND WI/WRN UPPER MI BY EARLY
TONIGHT. A COLD FRONT TRAILING THIS LOW WILL MOVE EWD ACROSS THE
MID MS VALLEY TODAY AND SEWD INTO THE LOWER MS VALLEY BY TONIGHT.
THE OVERALL SYNOPTIC SYSTEM WILL REACH PEAK INTENSITY EARLY
TODAY...AND THEN BEGIN TO WEAKEN SLOWLY INTO TONIGHT.
...LOWER MS VALLEY AREA...
REMNANTS OF AN ONGOING LINE OF STORMS JUST E OF THE COLD FRONT WILL
LIKELY PERSIST TODAY ACROSS AR/ERN MO/IL. THIS CONVECTION WILL TEND
TO STABILIZE THE LOW LEVELS THROUGH MIDDAY ACROSS SRN MO AND NW AR.
MEANWHILE...THE RICHEST BOUNDARY LAYER MOISTURE /MID-UPPER 60S
DEWPOINTS/ SHOULD BE CONFINED PRIMARILY TO AREAS S OF THE CONFLUENCE
OF THE MS/OH RIVERS. THESE FACTORS SUGGEST THAT THE MORE
SUBSTANTIAL SEVERE STORM THREAT WILL COINCIDE WITH THE MORE UNSTABLE
WARM SECTOR ACROSS ERN AR/NW MS/WRN TN. HERE...THE POTENTIAL FOR
SUPERCELLS WILL EXIST WITHIN THE REMNANT SQUALL LINE...AS WELL AS
WITH SCATTERED PRE-FRONTAL CONVECTION ALONG THE MOIST AXIS.
LOW-LEVEL SHEAR IS EXPECTED TO REMAIN RELATIVELY STRONG OVER THIS
CORRIDOR IN CONJUNCTION WITH A 45-55 KT LLJ...WHILE DEEP LAYER SHEAR
WILL INCREASE WITH THE APPROACH OF THE MID LEVEL WAVE FROM THE WEST.
IF SUFFICIENT SURFACE HEATING CAN OCCUR WITHIN CLOUD BREAKS...A
STRONG TORNADO OR TWO COULD OCCUR THIS AFTERNOON...IN ADDITION TO
DAMAGING WINDS AND LARGE HAIL.
...MID MS VALLEY AREA...
THE SEVERE STORM THREAT FROM MO/IL NWD IS MORE QUESTIONABLE GIVEN
THE STABILIZING INFLUENCE OF THE ONGOING CONVECTION AND WIDESPREAD
CLOUDS. THE 12Z ILX/DVN SOUNDINGS SHOW SUFFICIENT ELEVATED
INSTABILITY FOR AT LEAST ISOLATED LARGE HAIL THIS MORNING ACROSS
IL/WI AND PERHAPS INDIANA. THE SEVERE STORM THREAT BECOMES MORE
UNCERTAIN LATER TODAY...IN THE WAKE OF THE ONGOING MORNING SQUALL
LINE. BOUNDARY LAYER DEWPOINTS SHOULD REMAIN IN THE MID-UPPER 50S
WITHIN THE OVERTURNED AIR MASS...AND RESIDUAL CLOUDS SHOULD LIMITED
SURFACE HEATING AND SUPPORT ONLY WEAK SURFACE-BASED INSTABILITY THIS
AFTERNOON/EVENING AHEAD OF THE COLD FRONT AND SURFACE LOW.
ADDITIONAL THUNDERSTORM DEVELOPMENT MAY OCCUR IN A NARROW BAND ALONG
THE COLD FRONT THIS AFTERNOON FROM ERN MO NWD ACROSS IL INTO EXTREME
ERN IA AND SRN WI...POSING A THREAT FOR ISOLATED DAMAGING WINDS AND
MARGINALLY SEVERE HAIL...AS WELL AS AN ISOLATED TORNADO OR TWO.
..THOMPSON/CROSBIE.. 05/02/2008
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NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1630Z