Alert archive / Wisconsin / Mesoscale Discussions in 2004

Mesoscale Discussion 621

May 9, 20044 states

The Storm Prediction Center issued this mesoscale discussion at May 9, 2004, 4:46 PM CDT for 4 states. It was in force for 59 min.

The area

The outline as issued.

The facts

Issued: May 9, 2004, 4:46 PM CDT (21:46 UTC)
Expired: May 9, 2004, 5:45 PM CDT
In force: 59 min
Issued by: the Storm Prediction Center

All 51 counties

Allamakee County, IA, Buchanan County, IA, Clayton County, IA, Clinton County, IA, Delaware County, IA, Dubuque County, IA, Fayette County, IA, Jackson County, IA, Jones County, IA, Scott County, IA, Boone County, IL, Bureau County, IL, Carroll County, IL, DeKalb County, IL, Grundy County, IL, Henry County, IL, Jo Daviess County, IL, Kane County, IL, Kendall County, IL, LaSalle County, IL, Lee County, IL, McHenry County, IL, Ogle County, IL, Stephenson County, IL, Whiteside County, IL, Winnebago County, IL, Houston County, MN, Adams County, WI, Columbia County, WI, Crawford County, WI, Dane County, WI, Dodge County, WI, Fond du Lac County, WI, Grant County, WI, Green County, WI, Green Lake County, WI, Iowa County, WI, Jefferson County, WI, Juneau County, WI, La Crosse County, WI, Lafayette County, WI, Marquette County, WI, Monroe County, WI, Richland County, WI, Rock County, WI, Sauk County, WI, Vernon County, WI, Walworth County, WI, Washington County, WI, Waukesha County, WI, Waushara County, WI

The radar

The Milwaukee radar (KMKX), 117 km from the middle of the area, began a volume at 21:47 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, 9.8 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-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: 69 J/kg
Mixed-layer CIN: -248 J/kg
Mixed-layer LCL: 1608 m above ground
0-6 km bulk shear: 18 kt
0-1 km storm-relative helicity: -5 m²/s²
0-3 km storm-relative helicity: 10 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 092146
SWOMCD
SPC MCD 092146 
ILZ000-WIZ000-IAZ000-MNZ000-092245-

MESOSCALE DISCUSSION 0621
NWS STORM PREDICTION CENTER NORMAN OK
0446 PM CDT SUN MAY 09 2004

AREAS AFFECTED...NRN IL...EXTREME NERN I AND SRN WI

CONCERNING...SEVERE THUNDERSTORM POTENTIAL 

VALID 092146Z - 092245Z

MONITORING EXTREME NERN IA....NRN IL AND SRN WI FOR A POSSIBLE
WATCH.

ALTHOUGH CONVERGENCE IS WEAK...CONVECTION HAS DEVELOPED RECENTLY
FROM 30 W OF DBQ TO 20 W MMO. THE CONVECTION IS MOVING NEWD THROUGH
AN AIR MASS THAT IS MODERATELY UNSTABLE WITH TEMPERATURES IN THE MID
80S. DEEP UNIDIRECTIONAL WSWLY FLOW IS FAVORABLE FOR STORMS TO
CONTINUE DEVELOP/SPREAD NEWD INTO THE EVENING HOURS AND MAY
INTENSIFY AS THEY INTERACT WITH WARM FRONT LOCATED ACROSS SRN WI.
POTENTIAL FOR WIND DAMAGE AND SOME SEVERE HAIL ARE POSSIBLE WITH
THESE STORMS.

..IMY.. 05/09/2004

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

ATTN...WFO...GRB...LOT...MKX...DVN...ARX...

41248824 41349032 42349198 43359182 44159127 44248967
43778795

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 8, 9:55 PM CDT	Mesoscale Discussion	SPC	Boone, Cook, Lake, McHenry, Stephenson, Winnebago	2 hr
May 9, 1:22 AM CDT	Mesoscale Discussion	SPC	Hancock	23 min
May 9, 11:48 AM CDT	Mesoscale Discussion	SPC	Boone, Cook, DeKalb, DuPage, Kane, Lake and 4 more	2 hr
May 9, 12:55 PM CDT	Severe Thunderstorm Watch	SPC	Cook, DuPage, Lake, Will	6 hr
May 9, 2:46 PM CDT	Mesoscale Discussion	SPC	Cook, Lake	89 min
May 9, 5:17 PM CDT	Mesoscale Discussion	SPC	Cook, DuPage, Lake, Will	88 min
May 9, 6:50 PM CDT	Severe Thunderstorm Watch	SPC	Cook, DuPage, Grundy, Kankakee, Kendall, LaSalle and 3 more	4 hr
May 8, 7:54 PM CDT	Mesoscale Discussion	SPC	Adair, Adams, Audubon, Carroll, Cass, Clarke and 19 more	2 hr
May 8, 8:25 PM CDT	Severe Thunderstorm Watch	SPC	Adair, Adams, Allamakee, Appanoose, Audubon, Benton and 58 more	6 hr
May 8, 10:44 PM CDT	Mesoscale Discussion	SPC	Adair, Adams, Cass, Clarke, Decatur, Fremont and 12 more	2 hr
May 9, 2:30 PM CDT	Severe Thunderstorm Watch	SPC	Lyon, Sioux	6 hr
May 9, 5:38 PM CDT	Mesoscale Discussion	SPC	Dickinson, Emmet, Lyon, Osceola, Sioux	2 hr
May 9, 2:00 PM CDT	Mesoscale Discussion	SPC	Big Stone, Blue Earth, Brown, Carver, Chippewa, Kandiyohi and 19 more	3 hr
May 9, 3:29 PM CDT	Mesoscale Discussion	SPC	Chisago, Dakota, Goodhue, Hennepin, Le Sueur, Ramsey and 4 more	91 min
May 9, 3:55 PM CDT	Tornado Watch	SPC	Anoka, Blue Earth, Brown, Carver, Dakota, Dodge and 24 more	5 hr
May 9, 6:15 PM CDT	Severe Thunderstorm Watch	SPC	Ashland, Barron, Bayfield, Douglas, Forest, Iron and 6 more	8 hr

Nearby

Mesoscale Discussions in Wisconsin, 2004 Mesoscale Discussions in Illinois, 2004 Mesoscale Discussions in Iowa, 2004 Every mesoscale discussion in 2004

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.