Alert archive / Iowa / Mesoscale Discussions in 2010

Mesoscale Discussion 1621

August 8, 20104 states

The Storm Prediction Center issued this mesoscale discussion at Aug 8, 2010, 8:57 PM CDT for 4 states. It was in force for 63 min.

The area

The outline as issued.

The facts

Issued
Aug 8, 2010, 8:57 PM CDT (01:57 UTC)
Expired
Aug 8, 2010, 10:00 PM CDT
In force
63 min
Issued by
the Storm Prediction Center
All 60 counties

Audubon County, IA, Boone County, IA, Buena Vista County, IA, Calhoun County, IA, Carroll County, IA, Cerro Gordo County, IA, Cherokee County, IA, Clay County, IA, Crawford County, IA, Dallas County, IA, Dickinson County, IA, Emmet County, IA, Franklin County, IA, Greene County, IA, Guthrie County, IA, Hamilton County, IA, Hancock County, IA, Hardin County, IA, Harrison County, IA, Humboldt County, IA, Ida County, IA, Kossuth County, IA, Marshall County, IA, Monona County, IA, O'Brien County, IA, Osceola County, IA, Palo Alto County, IA, Plymouth County, IA, Pocahontas County, IA, Sac County, IA, Shelby County, IA, Sioux County, IA, Story County, IA, Webster County, IA, Winnebago County, IA, Woodbury County, IA, Worth County, IA, Wright County, IA, Faribault County, MN, Freeborn County, MN, Jackson County, MN, Martin County, MN, Boone County, NE, Burt County, NE, Colfax County, NE, Cuming County, NE, Dakota County, NE, Dixon County, NE, Dodge County, NE, Douglas County, NE, Greeley County, NE, Madison County, NE, Pierce County, NE, Platte County, NE, Saunders County, NE, Stanton County, NE, Thurston County, NE, Washington County, NE, Wayne County, NE, Union County, SD

The radar

The Omaha radar (KOAX), 130 km from the middle of the area, began a volume at 01:58 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 watches that followed

Watches SPC issued over any of the same counties within four hours of this discussion.

The nearest sounding before it

Omaha, NE (KOAX), launched 00:00Z, 2.0 hours before the alert went out and 130 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-pSkew-T log-p diagram, Omaha, NE at 00:00Z on 2010-08-09Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 5222 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Omaha, NE at 00:00Z on 2010-08-09The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 152 square meters per square second.193958Sfc1 km3 km6 km9 kmRMLM
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
5222 J/kg
Mixed-layer CIN
-59 J/kg
Mixed-layer LCL
1308 m above ground
0-6 km bulk shear
29 kt
0-1 km storm-relative helicity
152 m²/s²
0-3 km storm-relative helicity
313 m²/s²
Significant tornado parameter
4.7
Supercell composite
43.1

Open this sounding in Storm Lab

The text

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

022 
ACUS11 KWNS 090158
SWOMCD
SPC MCD 090157
IAZ000-MNZ000-NEZ000-SDZ000-090300-

MESOSCALE DISCUSSION 1621
NWS STORM PREDICTION CENTER NORMAN OK
0857 PM CDT SUN AUG 08 2010

AREAS AFFECTED...ECNTRL NEB...CNTRL/NRN IA

CONCERNING...SEVERE THUNDERSTORM WATCH 587...592...

VALID 090157Z - 090300Z

THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH
587...592...CONTINUES.

SEVERE THUNDERSTORM WATCH 587 IS SET TO EXPIRE AT 03Z.
HOWEVER...LOCAL WFO EXTENSION OF THE WATCH /OR TRANSFER OF COUNTIES
INTO NEIGHBORING WW 591/ MAY BE NEEDED OVER PARTS OF SCNTRL MN.

BOWING MCS WAS MOVING E AT 45 KTS ACROSS WCNTRL/NWRN IA AT 0145Z.
EXTRAPOLATION HAS STORMS REACHING THE I-35 CORRIDOR FROM JUST N OF
AMES TO MASON CITY BY 0230-0315Z.  STORMS WERE TRAVERSING THROUGH
EXTREME AMOUNTS OF CAPE...ON THE ORDER OF 5600 J/KG MLCAPE PER OAX
SOUNDING.  MEAN WSW FLOW ABOVE 850 MB /30 KTS AT H5/ AND FAVORABLE
THERMODYNAMICS FOR PRECIPITATION-LOADED DOWNDRAFTS HAVE MAINTAINED
THE BOW ECHO STORM MODE.  EXPECT POSSIBILITY OF PARTICULARLY
DAMAGING WIND GUSTS ESPECIALLY FROM AROUND FORT DODGE/WEBSTER CITY
EWD TO IOWA FALLS ALONG U.S. 20 THROUGH 03Z.

MEANWHILE...STORMS CONTINUE N OF THE SWD MOVING OUTFLOW ACROSS
ECNTRL NEB.  THESE STORMS WERE BEING FED BY STRONG BUOYANCY ALONG 35
KT SWLY LLJ.  INTERESTINGLY...A TORNADO WAS REPORTED WITH THE STORM
OVER MONONA COUNTY IA WELL N OF THE OUTFLOW BOUNDARY.
TYPICALLY...LARGE HAIL CAN BE EXPECTED WITH THESE STORMS ALONG WITH
VERY HEAVY RAINFALL AS STORMS TRAIN EWD ACROSS AREAS NEAR/N OF
OMAHA.

..RACY.. 08/09/2010

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

ATTN...WFO...MPX...DMX...FSD...OAX...GID...LBF...

LAT...LON   41579882 43839526 43879332 42699305 41869277 41489471
            41219672 41579882

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Aug 8, 7:05 PM CDTSevere Thunderstorm WatchSPCAdair, Audubon, Black Hawk, Boone, Bremer, Butler and 33 more7 hr
Aug 8, 9:40 PM CDTMesoscale DiscussionSPCAllamakee, Benton, Buchanan, Cedar, Chickasaw, Clayton and 17 more95 min
Aug 8, 10:08 PM CDTSevere Thunderstorm WatchSPCAdams, Allamakee, Benton, Buchanan, Cedar, Chickasaw and 31 more7 hr
Aug 8, 10:14 PM CDTMesoscale DiscussionSPCAudubon, Benton, Boone, Carroll, Cedar, Crawford and 17 more3 hr
Aug 8, 11:19 PM CDTMesoscale DiscussionSPCAdair, Allamakee, Audubon, Benton, Black Hawk, Boone and 62 more86 min
Aug 9, 2:20 AM CDTMesoscale DiscussionSPCAllamakee, Appanoose, Benton, Black Hawk, Boone, Bremer and 54 more100 min
Aug 9, 4:46 AM CDTMesoscale DiscussionSPCAppanoose, Cedar, Clarke, Davis, Decatur, Des Moines and 22 more3 hr
Aug 8, 8:09 PM CDTMesoscale DiscussionSPCCass, Itasca, Koochiching, Saint Louis96 min
Aug 8, 8:22 PM CDTSevere Thunderstorm WatchSPCCass, Itasca, Koochiching, Saint Louis4 hr
Aug 8, 10:27 PM CDTMesoscale DiscussionSPCCarlton, Cass, Itasca, Koochiching, Saint Louis93 min
Aug 9, 3:48 PM CDTMesoscale DiscussionSPCArthur, Box Butte, Chase, Cheyenne, Dawes, Deuel and 9 more87 min
Aug 9, 5:53 PM CDTMesoscale DiscussionSPCChase, Cheyenne, Dawson, Deuel, Dundy, Frontier and 9 more97 min
Aug 9, 6:26 PM CDTSevere Thunderstorm WatchSPCArthur, Banner, Blaine, Brown, Chase, Cherry and 27 more8 hr

Nearby

Mesoscale Discussions in Iowa, 2010Mesoscale Discussions in Nebraska, 2010Mesoscale Discussions in Minnesota, 2010Every mesoscale discussion in 2010

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.