Alert archive / Iowa / Mesoscale Discussions in 2007

Mesoscale Discussion 2000

September 21, 200730 counties in Iowa; Houston County, Minnesota; Crawford County, Grant County, Vernon County, Wisconsin

The Storm Prediction Center issued this mesoscale discussion at Sep 21, 2007, 3:17 PM CDT for 30 counties in Iowa; Houston County, Minnesota; Crawford County, Grant County, Vernon County, Wisconsin. It was in force for 88 min.

The area

The outline as issued.

The facts

Issued
Sep 21, 2007, 3:17 PM CDT (20:17 UTC)
Expired
Sep 21, 2007, 4:45 PM CDT
In force
88 min
Issued by
the Storm Prediction Center
All 34 counties

Allamakee County, IA, Benton County, IA, Black Hawk County, IA, Bremer County, IA, Buchanan County, IA, Butler County, IA, Chickasaw County, IA, Clayton County, IA, Dallas County, IA, Delaware County, IA, Dubuque County, IA, Fayette County, IA, Floyd County, IA, Grundy County, IA, Hardin County, IA, Howard County, IA, Iowa County, IA, Jasper County, IA, Linn County, IA, Lucas County, IA, Madison County, IA, Mahaska County, IA, Marion County, IA, Marshall County, IA, Polk County, IA, Poweshiek County, IA, Story County, IA, Tama County, IA, Warren County, IA, Winneshiek County, IA, Houston County, MN, Crawford County, WI, Grant County, WI, Vernon County, WI

The radar

The La Crosse radar (KARX), 136 km from the middle of the area, began a volume at 20:18 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

Davenport, (KDVN), launched 12:00Z, 8.3 hours before the alert went out and 189 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, Davenport, at 12:00Z on 2007-09-21Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 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, Davenport, at 12:00Z on 2007-09-21The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 37 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
1379 m above ground
0-6 km bulk shear
21 kt
0-1 km storm-relative helicity
37 m²/s²
0-3 km storm-relative helicity
67 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.

000 
ACUS11 KWNS 212018
SWOMCD
SPC MCD 212017 
WIZ000-IAZ000-MNZ000-212145-

MESOSCALE DISCUSSION 2000
NWS STORM PREDICTION CENTER NORMAN OK
0317 PM CDT FRI SEP 21 2007

AREAS AFFECTED...FAR SOUTHEAST MN/SOUTHWEST WI AND EASTERN/CENTRAL
IA

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 

VALID 212017Z - 212145Z

CLOSELY MONITORING FOR THE POSSIBILITY OF A SEVERE THUNDERSTORM
WATCH FROM SOUTHEAST MN/SOUTHWEST WI INTO MUCH OF CENTRAL/EASTERN
IA...A WATCH COULD BE NEEDED FOR PORTIONS OF THE REGION WITHIN THE
HOUR. THE STRONGEST STORMS WILL POSE A RISK OF DAMAGING WIND GUSTS
AND LARGE HAIL.

SOUTH OF TORNADO WATCH 670 ACROSS WI/U.P. OF MI...STORMS ARE RAPIDLY
INCREASING ALONG/JUST AHEAD OF SURFACE FRONTAL ZONE FROM SOUTHEAST
MN INTO EAST CENTRAL IA. AMPLE INSOLATION/MOISTURE HAS LEAD TO THE
DEVELOPMENT OF MODERATE INSTABILITY...WITH QUICKLY WEAKENING
INHIBITION AND A CORRIDOR OF MLCAPE GREATER THAN 1000 J/KG JUST
AHEAD OF THE COLD FRONT. WHILE MID LEVEL TEMPERATURES WARM AND LOW
TO MID TROPOSPHERIC WIND FIELDS ACROSS THE WARM SECTOR WEAKEN WITH
SOUTH EXTENT...THE STRONGEST STORMS WILL NEVERTHELESS BE CAPABLE OF
DAMAGING WIND GUSTS/LARGE HAIL THROUGH EARLY EVENING.

..GUYER.. 09/21/2007

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

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

43849186 43719068 42949013 40839325 41499426 43029290

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Sep 20, 8:40 PM CDTMesoscale DiscussionSPCLyon95 min
Sep 21, 3:53 PM CDTSevere Thunderstorm WatchSPCAdair, Allamakee, Benton, Black Hawk, Boone, Bremer and 26 more4 hr
Sep 21, 6:17 PM CDTMesoscale DiscussionSPCBenton, Cedar, Clinton, Delaware, Des Moines, Dubuque and 16 more88 min
Sep 20, 11:13 PM CDTSevere Thunderstorm WatchSPCAitkin, Carlton, Cass, Cook, Crow Wing, Itasca and 4 more7 hr
Sep 21, 12:00 AM CDTTornado WatchSPCBecker, Beltrami, Benton, Big Stone, Chippewa, Clay and 28 more6 hr
Sep 21, 3:08 AM CDTMesoscale DiscussionSPCAitkin, Carlton, Cook, Itasca, Koochiching, Lake and 2 more2 hr
Sep 21, 3:29 AM CDTMesoscale DiscussionSPCBecker, Beltrami, Benton, Big Stone, Chippewa, Clay and 27 more2 hr
Sep 21, 6:04 AM CDTSevere Thunderstorm WatchSPCAitkin, Anoka, Benton, Carlton, Carver, Cass and 24 more5 hr
Sep 21, 1:34 PM CDTMesoscale DiscussionSPCChisago, Cook, Dakota, Dodge, Fillmore, Freeborn and 10 more116 min
Sep 20, 11:09 PM CDTMesoscale DiscussionSPCBarron, Burnett, Chippewa, Clark, Dunn, Eau Claire and 9 more81 min
Sep 21, 10:24 AM CDTMesoscale DiscussionSPCAdams, Brown, Calumet, Clark, Columbia, Dodge and 27 more66 min
Sep 21, 2:46 PM CDTTornado WatchSPCAdams, Ashland, Bayfield, Chippewa, Clark, Eau Claire and 25 more8 hr
Sep 21, 6:49 PM CDTMesoscale DiscussionSPCBrown, Door, Kewaunee, Manitowoc, Sheboygan86 min

Nearby

Mesoscale Discussions in Iowa, 2007Mesoscale Discussions in Wisconsin, 2007Mesoscale Discussions in Minnesota, 2007Every mesoscale discussion in 2007

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.