Alert archive / Iowa / Mesoscale Discussions in 2012

Mesoscale Discussion 676

May 3, 201224 counties in Iowa

The Storm Prediction Center issued this mesoscale discussion at May 3, 2012, 2:12 PM CDT for 24 counties in Iowa. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: May 3, 2012, 2:12 PM CDT (19:12 UTC)
Expired: May 3, 2012, 4:15 PM CDT
In force: 2 hr
Issued by: the Storm Prediction Center
Chance of a watch: 40%

All 24 counties

Buena Vista County, IA, Calhoun County, IA, Cerro Gordo County, IA, Cherokee County, IA, Clay County, IA, Dickinson County, IA, Emmet County, IA, Hancock County, IA, Humboldt County, IA, Ida County, IA, Kossuth County, IA, Lyon County, IA, Mitchell County, IA, O'Brien County, IA, Osceola County, IA, Palo Alto County, IA, Plymouth County, IA, Pocahontas County, IA, Sac County, IA, Sioux County, IA, Winnebago County, IA, Woodbury County, IA, Worth County, IA, Wright County, IA

The radar

The Des Moines radar (KDMX), 163 km from the middle of the area, began a volume at 19:11 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

Minneapolis, MN (KMPX), launched 12:00Z, 7.2 hours before the alert went out and 221 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: 1755 J/kg
Mixed-layer CIN: -7 J/kg
Mixed-layer LCL: 521 m above ground
0-6 km bulk shear: 31 kt
0-1 km storm-relative helicity: 27 m²/s²
0-3 km storm-relative helicity: 33 m²/s²
Significant tornado parameter: 0.1
Supercell composite: 0.3

Open this sounding in Storm Lab

The text

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

598 
ACUS11 KWNS 031913
SWOMCD
SPC MCD 031912
IAZ000-MNZ000-NEZ000-SDZ000-032115-

MESOSCALE DISCUSSION 0676
NWS STORM PREDICTION CENTER NORMAN OK
0212 PM CDT THU MAY 03 2012

AREAS AFFECTED...NW/N-CNTRL IA

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 031912Z - 032115Z

PROBABILITY OF WATCH ISSUANCE...40 PERCENT

SUMMARY...ISOLATED THUNDERSTORM DEVELOPMENT IS EXPECTED OVER THE
NEXT FEW HOURS WITH A MARGINAL SEVERE HAIL/WIND THREAT. ISOLATED
COVERAGE SHOULD PRECLUDE THE NEED FOR WW ALTHOUGH TRENDS WILL BE
MONITORED CLOSELY.

DISCUSSION...LATEST VISIBLE SATELLITE IMAGERY REVEALS AN ENHANCED CU
FIELD ACROSS NRN IA INVOF A RESIDUAL OUTFLOW BOUNDARY FROM EARLIER
CONVECTION OVER SRN MN. AIR MASS ACROSS MUCH OF IA IS STILL
RECOVERING IN THE WAKE OF EARLY MORNING CONVECTION BUT ABUNDANT
SUNSHINE HAS ALLOWED THE ATMOSPHERE OVER NW IA TO RECOVER QUICKLY
AND AN AXIS OF MLCAPE VALUE NEAR 1000 J/KG EXISTS ACROSS THE AREA.
COMBINATION OF THE AFOREMENTIONED OUTFLOW BOUNDARY AND A SUBTLE
SHORTWAVE TROUGH NOTED IN WATER VAPOR IMAGERY MAY RESULT IN INCREASE
OF THUNDERSTORMS. MARGINAL EFFECTIVE BULK SHEAR VALUES ON THE ORDER
OF 25-30 KTS COULD SUPPORT SOME UPDRAFT ORGANIZATION WITH HAIL
POSSIBLE.

..MOSIER/BUNTING/CARBIN.. 05/03/2012

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

ATTN...WFO...ARX...MPX...DMX...FSD...

LAT...LON   43079653 43379628 43479591 43489512 43489450 43509381
            43559310 43619276 43639256 43559249 43259264 42969318
            42709355 42499410 42329463 42239537 42259573 42359624
            42479650 42669659 43079653

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 2, 10:43 PM CDT	Mesoscale Discussion	SPC	Harrison, Monona, Plymouth, Sioux, Woodbury	62 min
May 3, 12:50 AM CDT	Severe Thunderstorm Watch	SPC	Adams, Cass, Fremont, Mills, Montgomery, Page and 2 more	4 hr
May 3, 3:05 AM CDT	Mesoscale Discussion	SPC	Adair, Adams, Cass, Clarke, Decatur, Montgomery and 4 more	85 min
May 3, 3:41 PM CDT	Mesoscale Discussion	SPC	Adair, Adams, Cass, Clarke, Fremont, Madison and 7 more	2 hr
May 3, 6:42 PM CDT	Mesoscale Discussion	SPC	Appanoose, Davis, Decatur, Des Moines, Henry, Lee and 5 more	63 min

Nearby

Mesoscale Discussions in Iowa, 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.