MESOSCALE DISCUSSION 2097
NWS STORM PREDICTION CENTER NORMAN OK
0241 PM CDT FRI SEP 02 2011

AREAS AFFECTED…ERN NEB THROUGH CNTRL IA INTO SRN WI/NRN IL

CONCERNING…SEVERE POTENTIAL…WATCH POSSIBLE

VALID 021941Z – 022115Z

THE THREAT FOR SEVERE STORMS CAPABLE OF MAINLY DAMAGING WINDS AND
HAIL IS EXPECTED TO INCREASE ACROSS DISCUSSION AREA THROUGH MID-LATE
AFTERNOON. CONVECTIVE TRENDS ARE BEING MONITORED FOR A WATCH.

CURRENT SURFACE ANALYSIS AND REGIONAL VAD/PROFILER DATA INDICATE
THAT DEEPER-LAYER BAROCLINIC ZONE EXTENDS FROM NERN WI SWWD THROUGH
SWRN MN INTO S-CNTRL NEB…WITH MULTIPLE CONVECTIVE OUTFLOW
BOUNDARIES OBSERVED ACROSS PRE-FRONTAL WARM SECTOR. THOUGH DENSER
CLOUDINESS HAS PERSISTED INVOF SYNOPTIC FRONT…THE CORRIDOR FROM
E-CNTRL NEB EWD THROUGH CNTRL IA INTO NRN IL HAS EXPERIENCED
COMPARABLY STRONGER INSOLATION. HERE…BOUNDARY LAYER DEWPOINTS IN
THE MID 60S TO UPPER 70S AND STEEP MIDLEVEL LAPSE RATES HAVE
COMBINED WITH THE DAYTIME HEATING TO YIELD MLCAPE OF 2000-3500 J/KG
AND A WEAKENING CAP.

LARGE-SCALE FORCING IS FORECAST TO REMAIN RATHER WEAK ACROSS THE
REGION THROUGH THE REMAINDER OF THE DIURNAL HEATING CYCLE…CASTING
UNCERTAINTY ON WHERE AND WHEN SURFACE-BASED STORMS WILL DEVELOP.
ONE POSSIBLE LOCATION IS ALONG AN OUTFLOW BOUNDARY EXTENDING FROM E
OF FOD SWWD TO NEAR OMA WHERE VISIBLE SATELLITE DOES INDICATE SOME
DEEPENING CUMULUS.

SHOULD STORMS DEVELOP AND BECOME SUSTAINED…THE PRESENCE OF 30-35
KT WLY WINDS IN THE MIDLEVELS ATOP WEAK SELY/ELY SURFACE WINDS WILL
RESULT IN A KINEMATIC ENVIRONMENT SUPPORTIVE OF ORGANIZED STORM
MODES /INCLUDING SUPERCELLS/ CAPABLE OF MAINLY DAMAGING WINDS AND
HAIL.