SPC MD 890

MD 0890 CONCERNING SEVERE POTENTIAL…WATCH POSSIBLE FOR PORTIONS ERN IA…EXTREME NRN MO…SWRN WI…EXTREME NWRN IL — S OF WW 295.


MESOSCALE DISCUSSION 0890
NWS STORM PREDICTION CENTER NORMAN OK
0306 PM CDT THU MAY 24 2012

AREAS AFFECTED...PORTIONS ERN IA...EXTREME NRN MO...SWRN
WI...EXTREME NWRN IL -- S OF WW 295.

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 242006Z - 242200Z

PROBABILITY OF WATCH ISSUANCE...40 PERCENT

SUMMARY...CONVECTION IS INCREASING INVOF SFC COLD FRONT OVER
CENTRAL/SWRN IA AND OVER NWRN MO.  POTENTIAL EXISTS FOR TSTMS TO
EVOLVE FROM SOME OF THIS ACTIVITY AND MOVE EWD ACROSS PORTIONS IA SW
OF WW 295.  MAIN THREAT WILL BE DAMAGING GUSTS...WITH ISOLATED HAIL
ALSO POSSIBLE. WW APPEARS MORE PROBABLE IN NERN IA/SWRN WI VERSUS
ELSEWHERE IN DISCUSSION AREA.

DISCUSSION...AT 1945Z..SFC COLD FRONT EXTENDED SSWWD FROM SERN MN
LOW...ACROSS BOONE COUNTY IA TO BROWN COUNTY KS.  FRONT SHOULD MOVE
EWD/SEWD ACROSS IA...IMPINGING ON WARM SECTOR THAT SHOULD CONTINUE
TO DESTABILIZE FOR ANOTHER COUPLE OF HOURS.  CONVECTION WILL IMPINGE
ON NARROW CORRIDOR OF AT LEAST MRGLLY FAVORABLE WARM-SECTOR THETAE
OVER CENTRAL/SRN IA AND SWRN WI...SANDWICHED BETWEEN COLD FRONT AND
PLUME OF RELATIVE LOW-LEVEL DRYING FARTHER E THAT HAS BEEN INDICATED
PERSISTENTLY IN RAOB ANALYSES AND SATELLITE-DERIVED TOTAL-PW
IMAGERY.  MODIFIED FCST SOUNDINGS SUGGEST MLCAPE 1000-1500 J/KG WITH
50-100 NM AHEAD OF FRONT...ATOP WELL-MIXED/INVERTED-V THERMODYNAMIC
PROFILE IN BOUNDARY LAYER.  THIS REGIME...SET AMIDST 50-70 KT
EFFECTIVE SHEAR MAGNITUDE AND STG DEEP-LAYER WINDS ALIGNED NEARLY
PARALLEL TO FRONT...INDICATES QUASI-LINEAR CONVECTIVE MODE WITH
DAMAGING WIND POSSIBLE.  STRONGEST MID-UPPER LEVEL SUPPORT AND
LOW-LEVEL FRONTAL ASCENT SHOULD REMAIN N OF MO THROUGH
AFTERNOON...WHILE CINH INCREASES WITH SWD EXTENT.  THIS INDICATES
ANY CONVECTION S OF IA SHOULD REMAIN RELATIVELY SHORT-LIVED AND NOT
AS INTENSE AS FARTHER N.

..EDWARDS/WEISS.. 05/24/2012

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...MKX...DVN...ARX...DMX...EAX...

LAT...LON   43578991 42629016 42349029 41389134 40669271 39929513
            41179413 42489337 43519301 43489122 43578991

via SPC Forecast Products http://www.spc.noaa.gov/products/md/md0890.html