Alert archive / Iowa / Mesoscale Discussions in 2012

Mesoscale Discussion 895

May 25, 20124 states

The Storm Prediction Center issued this mesoscale discussion at May 25, 2012, 3:09 PM CDT for 4 states. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: May 25, 2012, 3:09 PM CDT (20:09 UTC)
Expired: May 25, 2012, 5:15 PM CDT
In force: 2 hr
Issued by: the Storm Prediction Center
Chance of a watch: 40%

All 63 counties

Adair County, IA, Adams County, IA, Appanoose County, IA, Audubon County, IA, Benton County, IA, Boone County, IA, Cass County, IA, Cedar County, IA, Clarke County, IA, Dallas County, IA, Davis County, IA, Decatur County, IA, Des Moines County, IA, Fremont County, IA, Guthrie County, IA, Harrison County, IA, Henry County, IA, Iowa County, IA, Jasper County, IA, Jefferson County, IA, Johnson County, IA, Keokuk County, IA, Lee County, IA, Linn County, IA, Louisa County, IA, Lucas County, IA, Madison County, IA, Mahaska County, IA, Marion County, IA, Marshall County, IA, Mills County, IA, Monroe County, IA, Montgomery County, IA, Muscatine County, IA, Page County, IA, Polk County, IA, Pottawattamie County, IA, Poweshiek County, IA, Ringgold County, IA, Shelby County, IA, Story County, IA, Tama County, IA, Taylor County, IA, Union County, IA, Van Buren County, IA, Wapello County, IA, Warren County, IA, Washington County, IA, Wayne County, IA, Henderson County, IL, Mercer County, IL, Atchison County, MO, Gentry County, MO, Harrison County, MO, Mercer County, MO, Nodaway County, MO, Putnam County, MO, Schuyler County, MO, Worth County, MO, Cass County, NE, Douglas County, NE, Sarpy County, NE, Washington County, NE

The radar

The Des Moines radar (KDMX), 86 km from the middle of the area, began a volume at 20:10 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.

The nearest sounding before it

Davenport, (KDVN), launched 12:00Z, 8.2 hours before the alert went out and 232 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

Mixed-layer CAPE: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 1310 m above ground
0-6 km bulk shear: 52 kt
0-1 km storm-relative helicity: -54 m²/s²
0-3 km storm-relative helicity: -60 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

286 
ACUS11 KWNS 252009
SWOMCD
SPC MCD 252009 
IAZ000-ILZ000-MOZ000-NEZ000-252215-

MESOSCALE DISCUSSION 0895
NWS STORM PREDICTION CENTER NORMAN OK
0309 PM CDT FRI MAY 25 2012

AREAS AFFECTED...PORTIONS NRN MO...SRN/ERN IA...EXTREME ERN
NEB...SMALL PART OF NWRN IL.

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 

VALID 252009Z - 252215Z

PROBABILITY OF WATCH ISSUANCE...40 PERCENT

SUMMARY...POTENTIAL FOR LARGE HAIL IS INCREASING WITH GROWING
COVERAGE OF ELEVATED TSTMS OVER MO/IA BORDER REGION.  ACTIVITY
SHOULD SPREAD ENEWD THROUGH REMAINDER AFTERNOON.

DISCUSSION...TSTMS HAVE DEVELOPED OVER WRN PORTIONS OF DISCUSSION
AREA...IN BROAD ZONE OF JUXTAPOSED LOW-LEVEL WAA AND INITIALLY
ELEVATED FRONTOGENETIC FORCING.  THIS ACTIVITY SHOULD CONTINUE TO
INCREASE IN COVERAGE FOR ANOTHER COUPLE HOURS WITH MAIN CONCERN
BEING LARGE HAIL.  SFC MESOANALYSIS SHOWS SYNOPTIC WARM FRONT STILL
WELL S OF REGION...OVER SERN KS AND S-CENTRAL MO...WITH
SECONDARY/DIFFERENTIAL-HEATING BOUNDARY CLOSER TO THIS ACTIVITY
ACROSS NWRN MO AND SWRN IA.  MODIFIED FCST SOUNDINGS SHOW FAVORABLE
BUOYANCY AND SHEAR WITHIN CONSTRAINTS OF CLOUD-BEARING/INFLOW LAYERS
ALOFT -- I.E. ELEVATED MUCAPE 500-1500 J/KG WITH EFFECTIVE SHEAR
MAGNITUDES IN 50-70 KT RANGE.  GIVEN STG SFC HEATING AND FAVORABLE
BOUNDARY-LAYER MOISTURE ON BOTH SIDES OF THIS BOUNDARY...SFC WARM
FRONT MAY TRANSLATE/MIX NWD RAPIDLY DURING NEXT 2-3 HOURS SUCH THAT
SFC-BASED EFFECTIVE INFLOW PARCELS MAY REACH SECONDARY BOUNDARY AND
BECOME ACCESSIBLE TO SOME CELLS ON SRN RIM OF THIS COMPLEX.  IF THIS
OCCURS...DAMAGING WIND THREAT WILL INCREASE...ALONG WITH
MRGL/CONDITIONAL TORNADO THREAT AS DEPICTED IN 20Z DAY-1 OUTLOOK. 
THAT SCENARIO IS VERY CONDITIONAL...HOWEVER...BULK OF CONVECTION
SHOULD REMAIN ELEVATED WITH HAIL THREAT.

..EDWARDS/CARBIN.. 05/25/2012

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

ATTN...WFO...DVN...DMX...EAX...OAX...

LAT...LON   40469224 40079448 40229546 40599597 41459659 41939518
            42189247 42189126 41709068 41049067 40589097 40469224

Nearby

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

Sources

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.