Alert archive / Iowa / Mesoscale Discussions in 2004

Mesoscale Discussion 971

May 29, 20044 states

The Storm Prediction Center issued this mesoscale discussion at May 29, 2004, 12:42 PM CDT for 4 states. It was in force for 93 min.

The area

The outline as issued.

The facts

Issued
May 29, 2004, 12:42 PM CDT (17:42 UTC)
Expired
May 29, 2004, 2:15 PM CDT
In force
93 min
Issued by
the Storm Prediction Center
All 73 counties

Adair County, IA, Appanoose County, IA, Audubon County, IA, Boone County, IA, Buena Vista County, IA, Calhoun County, IA, Carroll County, IA, Cass County, IA, Cherokee County, IA, Clarke County, IA, Clay County, IA, Crawford County, IA, Dallas County, IA, Davis County, IA, Greene County, IA, Guthrie County, IA, Hamilton County, IA, Hardin County, IA, Henry County, IA, Humboldt County, IA, Ida County, IA, Iowa County, IA, Jasper County, IA, Jefferson County, IA, Keokuk County, IA, Lucas County, IA, Lyon County, IA, Madison County, IA, Mahaska County, IA, Marion County, IA, Marshall County, IA, Monona County, IA, Monroe County, IA, O'Brien County, IA, Osceola County, IA, Palo Alto County, IA, Plymouth County, IA, Pocahontas County, IA, Polk County, IA, Poweshiek County, IA, Sac County, IA, Shelby County, IA, Sioux County, IA, Story County, IA, Union County, IA, Van Buren County, IA, Wapello County, IA, Warren County, IA, Washington County, IA, Webster County, IA, Woodbury County, IA, Rock County, MN, Cedar County, NE, Dakota County, NE, Dixon County, NE, Thurston County, NE, Bon Homme County, SD, Clay County, SD, Davison County, SD, Douglas County, SD, Hanson County, SD, Hutchinson County, SD, Kingsbury County, SD, Lake County, SD, Lincoln County, SD, McCook County, SD, Miner County, SD, Minnehaha County, SD, Moody County, SD, Sanborn County, SD, Turner County, SD, Union County, SD, Yankton County, SD

The radar

The Des Moines radar (KDMX), 51 km from the middle of the area, began a volume at 17:44 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 12:00Z, 5.7 hours before the alert went out and 184 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 12:00Z on 2004-05-29Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1045 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 12:00Z on 2004-05-29The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 235 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
1045 J/kg
Mixed-layer CIN
-319 J/kg
Mixed-layer LCL
1057 m above ground
0-6 km bulk shear
36 kt
0-1 km storm-relative helicity
235 m²/s²
0-3 km storm-relative helicity
190 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 291743
SWOMCD
SPC MCD 291742 
IAZ000-MNZ000-NEZ000-SDZ000-291915-

MESOSCALE DISCUSSION 0971
NWS STORM PREDICTION CENTER NORMAN OK
1242 PM CDT SAT MAY 29 2004

AREAS AFFECTED...MUCH OF IA...SERN SD...NERN NEB...SWRN MN

CONCERNING...SEVERE THUNDERSTORM POTENTIAL 

VALID 291742Z - 291915Z

SCATTERED THUNDERSTORMS ARE EXPECTED TO DEVELOP ALONG OUTFLOW
BOUNDARY AND WARM FRONT.  A WW COULD BE REQUIRED NEXT HOUR OR SO.

LATEST VISIBLE IMAGERY SHOWS MODERATE TO STRONG INSOLATION VICINITY
OF OLD OUTFLOW BOUNDARY DRAPED NW-SE OVER CENTRAL IA WITH BOUNDARY
LAYER CU INCREASING.  DEWPOINTS CONTINUE TO INCREASE INTO THE MID TO
UPPER 60S F THROUGH ADVECTION WHICH IS PROVIDING AN UNSTABLE AND
HIGH RH BOUNDARY LAYER.  CAP IS EXPECTED TO BREAK AS TEMPERATURES
APPROACH 80 F AS INDICATED BY RUC FORECAST SOUNDINGS.  AMPLE LOW
LEVEL HELICITY ALONG OUTFLOW BOUNDARY COULD ALLOW FOR THE
DEVELOPMENT OF TORNADOES.

COMPLICATING FACTOR AT THIS TIME IS MID LEVEL WIND FIELD WHICH WILL
HAVE AN IMPACT ON STORM MODE AND EVOLUTION.  SLA AND FBY PROFILERS
SHOWS ONLY 10-15 KTS BETWEEN 4 AND 5 KM AGL.  HOWEVER...THESE WINDS
ARE EXPECTED TO INCREASE LATER THIS AFTERNOON WITH APPROACHING
SHORTWAVE.  STORMS SHOULD THUS BECOME BETTER ORGANIZED WITH TIME.

..JEWELL.. 05/29/2004

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

ATTN...WFO...DVN...DMX...FSD...OAX...ABR...

40649231 40789351 41149458 41409515 43149838 43639840
44619789 42629367 41989244 41579166 40669130

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
May 28, 7:31 PM CDTMesoscale DiscussionSPCCherokee, Crawford, Harrison, Ida, Lyon, Monona and 6 more89 min
May 28, 9:03 PM CDTMesoscale DiscussionSPCAudubon, Buena Vista, Calhoun, Carroll, Cherokee, Clay and 24 more57 min
May 28, 9:50 PM CDTSevere Thunderstorm WatchSPCBuena Vista, Calhoun, Cherokee, Clay, Dickinson, Emmet and 15 more5 hr
May 28, 11:41 PM CDTMesoscale DiscussionSPCBuena Vista, Calhoun, Cherokee, Clay, Dickinson, Emmet and 16 more94 min
May 29, 2:05 PM CDTTornado WatchSPCBuena Vista, Calhoun, Cherokee, Clay, Dickinson, Emmet and 13 more8 hr
May 29, 3:05 PM CDTTornado WatchSPCCarroll, Crawford, Fremont, Harrison, Mills, Monona and 4 more7 hr
May 29, 4:35 PM CDTTornado WatchSPCAdair, Adams, Boone, Cass, Clarke, Dallas and 15 more5 hr
May 29, 5:01 PM CDTMesoscale DiscussionSPCBuena Vista, Calhoun, Cherokee, Clay, Dickinson, Emmet and 13 more119 min
May 29, 3:25 PM CDTSevere Thunderstorm WatchSPCBecker, Clay, Douglas, Grant, Norman, Otter Tail and 2 more6 hr
May 29, 1:02 PM CDTMesoscale DiscussionSPCAdams, Clay, Fillmore, Franklin, Gage, Hall and 10 more118 min
May 29, 1:54 PM CDTMesoscale DiscussionSPCChase, Dundy, Frontier, Hayes, Hitchcock, Perkins and 1 more3 hr
May 29, 3:55 PM CDTSevere Thunderstorm WatchSPCDundy, Furnas, Hitchcock, Red Willow6 hr
May 29, 5:16 PM CDTMesoscale DiscussionSPCAdams, Boone, Buffalo, Clay, Custer, Dawson and 20 more59 min
May 29, 5:53 PM CDTMesoscale DiscussionSPCHayes, Hitchcock, Red Willow67 min

Nearby

Mesoscale Discussions in Iowa, 2004Mesoscale Discussions in South Dakota, 2004Mesoscale Discussions in Nebraska, 2004Every 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.