Mesoscale Discussion 1644

Issued

Jul 29, 2012, 3:25 PM CDT (20:25 UTC)

Expired

Jul 29, 2012, 5:30 PM CDT

In force

2 hr

Issued by

the Storm Prediction Center

Chance of a watch

40%

The Quad Cities radar (KDVN), 160 km from the middle of the area, began a volume at 20:26 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

392 
ACUS11 KWNS 292026
SWOMCD
SPC MCD 292025
ILZ000-MOZ000-IAZ000-292230-

MESOSCALE DISCUSSION 1644
NWS STORM PREDICTION CENTER NORMAN OK
0325 PM CDT SUN JUL 29 2012

AREAS AFFECTED...PORTIONS CENTRAL-SERN IA...WRN IL...NERN MO.

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 292025Z - 292230Z

PROBABILITY OF WATCH ISSUANCE...40 PERCENT

SUMMARY...CONVECTIVE POTENTIAL IS INCREASING OVER PORTIONS
CENTRAL/SERN IA...WITH RISK FOR ANY SUSTAINED TSTMS TO PRODUCE
DAMAGING GUSTS AND LARGE HAIL.  RESULTING ACTIVITY MAY GROW UPSCALE
INTO ORGANIZED TSTM CLUSTER WITH LOCALLY ENHANCED WIND
POTENTIAL...AND MOVE SEWD OVER PORTIONS NERN MO AND WRN IL INVOF SFC
BOUNDARY.

DISCUSSION...SFC MESOANALYSIS SHOWS DIFFUSE CYCLONE OVER WRN
IA...WITH TROUGH EXTENDING SSWWD TO WEAK LOW IN NERN KS.  WARM
FRONT...DEMARCATING NRN PORTION OF VERY HOT/WELL-MIXED BOUNDARY
LAYERS IN CENTRAL/SRN PLAINS...WAS DRAWN FROM KS LOW SEWD ACROSS MKC
AREA AND SWRN MO.  QUASISTATIONARY DIFFERENTIAL-HEATING AND
CONVERGENCE BOUNDARY...MARKING WRN RIM OF EARLIER CLOUD COVER AND
PRECIP...WAS EVIDENT FROM BRL AREA NWWD ACROSS CENTRAL IA TO NEAR
SPW.  VIS IMAGERY SHOWS DEEPENING CU ALONG AND WITHIN ABOUT 60 NM SW
OF THAT BOUNDARY.  AIR MASS BETWEEN BOUNDARY AND WARM FRONT...AND E
OF SFC TROUGH...IS CHARACTERIZED BY STG SFC HEATING AND DEW POINTS
MID-UPPER 60S F...OFFSETTING MEAGER LOW-MIDDLE LEVEL LAPSE RATES
ENOUGH TO YIELD MLCAPE 1500-2500 J/KG IN FCST SOUNDINGS...BY 21-22Z
TIME FRAME.  BACKED/ELY SFC FLOW COMPONENT WILL CONTINUE TO ENHANCE
BOUNDARY-LAYER HODOGRAPHS AND STORM-RELATIVE INFLOW FOR ANY TSTMS
THAT FORM ALONG AND E OF BOUNDARY.  RESULTANT EFFECTIVE SRH 150-200
J/KG AND EFFECTIVE SHEAR MAGNITUDES 55-65 KT AND MAY SUPPORT AT
LEAST TRANSIENT SUPERCELL STRUCTURES...AS WELL AS POTENTIAL FOR
BOWS.

..EDWARDS/CORFIDI.. 07/29/2012

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

ATTN...WFO...ILX...LSX...DVN...DMX...EAX...

LAT...LON   40119256 41789364 42709426 42149210 40578942 39469044
            39129192 40119256

Mesoscale Discussions in Iowa, 2012Mesoscale Discussions in Illinois, 2012Mesoscale Discussions in Missouri, 2012Every mesoscale discussion in 2012

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.