• Mesodiscussion 0581 for 2013

Mesodiscussion 0581




MESOSCALE DISCUSSION 0581
NWS STORM PREDICTION CENTER NORMAN OK
0900 PM CDT MON APR 29 2013

AREAS AFFECTED...PORTIONS ERN IA...NRN IL...SRN WI.

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 

VALID 300200Z - 300400Z

PROBABILITY OF WATCH ISSUANCE...40 PERCENT

SUMMARY...ISOLATED/QUICKLY DEVELOPING SVR TSTM PRODUCED 2.5-INCH
HAIL REPORT NEAR DBQ AT 130Z.  PER COORD W/AFFECTED WFOS...NO WW IS
BEING ISSUED YET.  HOWEVER...CONVECTIVE TRENDS WILL BE MONITORED FOR
UPSCALE GROWTH THAT COULD COMPEL WW ISSUANCE...IN ENVIRONMENT THAT
SHOULD REMAIN FAVORABLE FOR OCNL LARGE HAIL FROM ANY SUSTAINED
CONVECTION.

DISCUSSION...ACTIVITY NEAR DBQ DEVELOPED NEAR DIFFUSE SFC WARM FRONT
EXTENDING WNWWD ACROSS SRN MN INTO ERN SD...AND ALSO..NEAR NERN END
OF FRONTOLYTIC WARM-FRONTAL CORRIDOR THAT EXTENDS INTO LOW OVER
CENTRAL/SWRN KS.  NEARBY DVN RAOB...IN WARM SECTOR...SAMPLED STEEP
MIDLEVEL LAPSE RATES AND INCREASING LOW-LEVEL MOISTURE...WITH
ROUGHLY 1-INCH PW SUPPORTING MLCAPE 800-900 J/KG.  MUCAPE FOR
INCREASINGLY MOIST PARCELS ROOTED AROUND 800-850 MB IS IN 2000-2500
J/KG RANGE...MORE REPRESENTATIVE OF RAPID INITIAL INTENSIFICATION
RATE OF CONVECTION OBSERVED SO FAR.  WITH NEAR-SFC
COOLING...ACTIVITY SHOULD BE MOSTLY ELEVATED...BUT WITH POTENTIAL TO
SEND ISOLATED STG/DAMAGING GUST THROUGH SHALLOW NEAR-SFC STABLE
LAYER.  MAIN CONCERN WILL BE HAIL.

SIGNALS FOR KINEMATIC SUPPORT ARE MIXED...WITH RELATIVELY WEAK
MID-UPPER WINDS LIMITING CLOUD-LAYER SHEAR.  HOWEVER...LOW-LEVEL WAA
AND RELATED VEERING OF WINDS WITH HEIGHT CONTRIBUTE TO FAVORABLE
EFFECTIVE SRH AROUND 200-250 J/KG.  THOUGH FIXED-LAYER SRH SHOULD
INCREASE BENEATH STRENGTHENING SWLY LLJ...NEAR-SFC DIABATIC
STABILIZATION WILL EFFECTIVELY TRUNCATE SOME OF THAT HELICITY IN
VERTICAL.  EFFECTIVE SHEAR MAGNITUDE 35-40 KT IS EXPECTED TO
CONTINUE.

..EDWARDS/KERR.. 04/30/2013

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

ATTN...WFO...LOT...MKX...DVN...ARX...DMX...

LAT...LON   43169230 43688963 43558777 43188791 42888782 42768775
            42518782 42168779 41978909 41799056 42089194 43169230