Alert archive / Iowa / Mesoscale Discussions in 2004

Mesoscale Discussion 593

May 8, 200443 counties in Iowa; 39 counties in Nebraska; Union County, South Dakota

The Storm Prediction Center issued this mesoscale discussion at May 8, 2004, 2:27 PM CDT for 43 counties in Iowa; 39 counties in Nebraska; Union County, South Dakota. It was in force for 3 hr.

The area

The outline as issued.

The facts

Issued
May 8, 2004, 2:27 PM CDT (19:27 UTC)
Expired
May 8, 2004, 5:00 PM CDT
In force
3 hr
Issued by
the Storm Prediction Center
All 83 counties

Adair County, IA, Audubon County, IA, Black Hawk County, IA, Boone County, IA, Bremer County, IA, Buena Vista County, IA, Butler County, IA, Calhoun County, IA, Carroll County, IA, Cass County, IA, Cerro Gordo County, IA, Cherokee County, IA, Clay County, IA, Crawford County, IA, Dallas County, IA, Franklin County, IA, Greene County, IA, Grundy County, IA, Guthrie County, IA, Hamilton County, IA, Hancock County, IA, Hardin County, IA, Harrison County, IA, Humboldt County, IA, Ida County, IA, Jasper County, IA, Kossuth County, IA, Madison County, IA, Marshall County, IA, Monona County, IA, Palo Alto County, IA, Plymouth County, IA, Pocahontas County, IA, Polk County, IA, Pottawattamie County, IA, Poweshiek County, IA, Sac County, IA, Shelby County, IA, Story County, IA, Tama County, IA, Webster County, IA, Woodbury County, IA, Wright County, IA, Antelope County, NE, Boone County, NE, Buffalo County, NE, Burt County, NE, Butler County, NE, Cedar County, NE, Colfax County, NE, Cuming County, NE, Custer County, NE, Dakota County, NE, Dawson County, NE, Dixon County, NE, Dodge County, NE, Douglas County, NE, Frontier County, NE, Furnas County, NE, Garfield County, NE, Gosper County, NE, Greeley County, NE, Hall County, NE, Hamilton County, NE, Harlan County, NE, Howard County, NE, Kearney County, NE, Madison County, NE, Merrick County, NE, Nance County, NE, Phelps County, NE, Pierce County, NE, Platte County, NE, Polk County, NE, Saunders County, NE, Sherman County, NE, Stanton County, NE, Thurston County, NE, Valley County, NE, Washington County, NE, Wayne County, NE, Wheeler County, NE, Union County, SD

The radar

The Omaha radar (KOAX), 58 km from the middle of the area, began a volume at 19:29 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, 7.5 hours before the alert went out and 58 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 2004-05-08Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 902 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 2004-05-08The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 248 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
902 J/kg
Mixed-layer CIN
-426 J/kg
Mixed-layer LCL
1108 m above ground
0-6 km bulk shear
19 kt
0-1 km storm-relative helicity
248 m²/s²
0-3 km storm-relative helicity
227 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.

629 
ACUS11 KWNS 081927
SWOMCD
SPC MCD 081927 
IAZ000-NEZ000-SDZ000-082200-

MESOSCALE DISCUSSION 0593
NWS STORM PREDICTION CENTER NORMAN OK
0227 PM CDT SAT MAY 08 2004

AREAS AFFECTED...SW THROUGH ERN NEB AND CNTRL IA

CONCERNING...SEVERE THUNDERSTORM POTENTIAL 

VALID 081927Z - 082200Z

SWRN THROUGH CNTRL AND ERN NEB AND CNTRL IA ARE BEING MONITORED FOR
THUNDERSTORM INITIATION BY 22Z-23Z. ONCE STORMS DEVELOP...THEY
SHOULD RAPIDLY BECOME SEVERE WITH ISOLATED LARGE HAIL AND DAMAGING
WIND GUSTS THE PRIMARY THREATS. ONCE INITIATION APPEARS IMMINENT...A
WW WILL BE ISSUED.

THIS AFTERNOON A STATIONARY FRONT PARTIALLY REINFORCED BY CONVECTIVE
OUTFLOW EXTENDS THROUGH CNTRL IA WWD THROUGH E CNTRL NEB THEN SWWD
TO A WEAK SURFACE LOW IN SW NEB. THE ATMOSPHERE S OF THIS BOUNDARY
IS BECOMING QUITE UNSTABLE WITH MLCAPE FROM 2000 TO 2500 J/KG IN
WARM SECTOR ACROSS SERN NEB THROUGH SW IA. THE ATMOSPHERE STILL
APPEARS TO BE CAPPED IN THIS REGION AND THIS IS PROVIDING
UNCERTAINTY WITH REGARD TO WHEN STORMS WILL DEVELOP. LATEST
OBJECTIVE ANALYSIS SHOWS THE CAP WEAKENING AS THE BOUNDARY LAYER
CONTINUES TO WARM...AND THE CAP MAY BECOME SUFFICIENTLY WEAK FOR
STORMS TO INITIATE BY LATE AFTERNOON OR EARLY EVENING. WV IMAGERY
ALSO SUGGESTS AN AREA OF MID/UPPER ASCENT ASSOCIATED WITH A WEAK
SHORTWAVE TROUGH MAY BE SPREADING INTO WRN NEB FROM ERN CO.

ONE AREA OF POSSIBLE INITIATION IS ACROSS ERN NEB THROUGH CNTRL IA
WHERE SSWLY LOW LEVEL FLOW IMPINGING ON THE BOUNDARY IS PROVIDING A
SOURCE OF ENHANCED LIFT. CONVERGENCE AND LIFT WILL INCREASE IN THIS
AREA TOWARD EVENING AS THE LOW LEVEL JET STRENGTHENS. ANOTHER
POSSIBLE AREA FOR INITIATION WILL BE NEAR THE SW PORTIONS OF THE
BOUNDARY ACROSS SW NEB WHERE DEEPER MIXING WILL LIKELY RESULT IN A
WEAKER CAP. THOUGH VERTICAL SHEAR PROFILES ARE MARGINAL...STORMS
THAT MOVE NEWD ALONG OR JUST N OF THE BOUNDARY WOULD ENCOUNTER
SUFFICIENT LOW LEVEL DIRECTIONAL SHEAR TO SUPPORT A THREAT FOR
SUPERCELLS.

..DIAL.. 05/08/2004

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

ATTN...WFO...DVN...ARX...DMX...FSD...OAX...GID...LBF...GLD...

42829212 41719220 41339359 41299483 41109711 40099960
40320055 41360004 42489820 43349442

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
May 7, 8:20 PM CDTMesoscale DiscussionSPCAllamakee, Benton, Buchanan, Clayton, Delaware, Dubuque and 5 more85 min
May 7, 9:53 PM CDTMesoscale DiscussionSPCBuena Vista, Calhoun, Cerro Gordo, Cherokee, Clay, Crawford and 21 more97 min
May 7, 10:20 PM CDTSevere Thunderstorm WatchSPCBlack Hawk, Boone, Bremer, Buena Vista, Butler, Calhoun and 38 more6 hr
May 8, 12:26 AM CDTMesoscale DiscussionSPCAllamakee, Clayton, Winneshiek64 min
May 8, 12:50 AM CDTSevere Thunderstorm WatchSPCAllamakee, Winneshiek6 hr
May 8, 2:27 AM CDTMesoscale DiscussionSPCBlack Hawk, Boone, Bremer, Buena Vista, Butler, Calhoun and 27 more93 min
May 8, 3:36 AM CDTMesoscale DiscussionSPCAllamakee, Winneshiek54 min
May 8, 5:35 AM CDTMesoscale DiscussionSPCAllamakee, Winneshiek55 min
May 8, 3:45 PM CDTSevere Thunderstorm WatchSPCAudubon, Benton, Black Hawk, Boone, Bremer, Buchanan and 38 more5 hr
May 8, 5:45 PM CDTMesoscale DiscussionSPCAdair, Adams, Audubon, Benton, Boone, Buena Vista and 33 more2 hr
May 8, 4:50 PM CDTSevere Thunderstorm WatchSPCAdams, Buffalo, Butler, Clay, Dawson, Franklin and 14 more4 hr
May 8, 6:56 PM CDTMesoscale DiscussionSPCAdams, Buffalo, Clay, Hall, Hamilton, Howard and 5 more2 hr
May 7, 7:34 PM CDTMesoscale DiscussionSPCButte, Lawrence, Meade86 min
May 8, 12:44 PM CDTMesoscale DiscussionSPCButte, Harding, Lawrence, Meade, Pennington, Perkins3 hr
May 8, 2:35 PM CDTSevere Thunderstorm WatchSPCButte, Dewey, Harding, Meade, Perkins, Stanley and 1 more5 hr
May 8, 5:11 PM CDTMesoscale DiscussionSPCButte, Dewey, Harding, Meade, Perkins, Stanley and 1 more64 min

Nearby

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