Alert archive / Nebraska / Mesoscale Discussions in 2003

Mesoscale Discussion 1663

July 6, 200341 counties in Iowa; 50 counties in Nebraska

The Storm Prediction Center issued this mesoscale discussion at Jul 6, 2003, 8:57 PM CDT for 41 counties in Iowa; 50 counties in Nebraska. It was in force for 3 hr.

The area

The outline as issued.

The facts

Issued
Jul 6, 2003, 8:57 PM CDT (01:57 UTC)
Expired
Jul 7, 2003, 12:00 AM CDT
In force
3 hr
Issued by
the Storm Prediction Center
All 91 counties

Adair County, IA, Adams 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, Crawford County, IA, Dallas County, IA, Greene County, IA, Grundy County, IA, Guthrie County, IA, Hamilton County, IA, Hardin County, IA, Harrison County, IA, Ida County, IA, Jasper County, IA, Lucas County, IA, Madison County, IA, Mahaska County, IA, Marion County, IA, Marshall County, IA, Mills County, IA, Monona County, IA, Montgomery 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, Union County, IA, Warren County, IA, Webster County, IA, Woodbury County, IA, Adams County, NE, Antelope County, NE, Boone County, NE, Buffalo County, NE, Burt County, NE, Butler County, NE, Cass County, NE, Cedar County, NE, Clay 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, Fillmore County, NE, Franklin 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, Knox County, NE, Madison County, NE, Merrick County, NE, Nance County, NE, Phelps County, NE, Pierce County, NE, Platte County, NE, Polk County, NE, Red Willow County, NE, Sarpy County, NE, Saunders County, NE, Seward County, NE, Sherman County, NE, Stanton County, NE, Thurston County, NE, Valley County, NE, Washington County, NE, Wayne County, NE, Webster County, NE, Wheeler County, NE, York County, NE

The radar

The Omaha radar (KOAX), 54 km from the middle of the area, began a volume at 02:01 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 54 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 2003-07-07Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 4152 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 2003-07-07The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 143 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
4152 J/kg
Mixed-layer CIN
-41 J/kg
Mixed-layer LCL
1702 m above ground
0-6 km bulk shear
43 kt
0-1 km storm-relative helicity
143 m²/s²
0-3 km storm-relative helicity
274 m²/s²
Significant tornado parameter
1.8
Supercell composite
103.4

Open this sounding in Storm Lab

The text

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

038 
ACUS11 KWNS 070158
SWOMCD
SPC MCD 070157 
IAZ000-NEZ000-SDZ000-KSZ000-070500-

MESOSCALE DISCUSSION 1663
NWS STORM PREDICTION CENTER NORMAN OK
0857 PM CDT SUN JUL 06 2003

AREAS AFFECTED...S-CENTRAL THROUGH NERN NEB...WRN IA

CONCERNING...SEVERE TSTM POTENTIAL...SEVERE THUNDERSTORM WATCH
659...

VALID 070157Z - 070500Z

SEVERE TSTM POTENTIAL INCREASING OVER PORTIONS S-CENTRAL/ERN NEB AND
WRN IA...WITH POTENTIAL FOR DAMAGING HAIL AND WIND.  A FEW TORNADOES
POSSIBLE AS WELL WHILE TSTMS ARE RELATIVELY DISCRETE AND NEARLY
SFC-BASED.  SUBSEQUENTLY WIND DAMAGE THREAT MAY BECOME BETTER
ORGANIZED WITH MCS DEVELOPING RAPIDLY AND MOVING ESEWD TOWARD
CENTRAL IA. WW LIKELY. 

TWO PRIMARY REGIMES RESPONSIBLE FOR INCREASED RISK NEXT FEW HOURS
ARE...
1. INCREASED LOW LEVEL MOISTENING...ASCENT AND FAVORABLE SHEAR
ACROSS MO VALLEY
2. CLUSTER OF TSTMS NOW OVER SWRN NEB -- IN WW 659 -- POSSIBLY
PROPAGATING NEWD TOWARD ERN NEB.  

SFC ANALYSIS SHOWS TRIPLE-POINT LOW SERN SD...COLD FRONT SWWD TOWARD
SWRN NEB...WARM FRONT ESEWD PAST SUX/DSM/DVN AREAS.  WARM FRONT
SHOULD DRIFT SLOWLY NWD THROUGH REMAINDER EVENING WHILE ISALLOBARIC
FORCING INCREASES OVER W-CENTRAL/NWRN IA...JUST AHEAD OF SFC LOW. 
25-35 KT LLJ CURRENTLY OBSERVED IN REGIONAL PROFILER DATA SHOULD
INCREASE TO 35-45 KT -- SUPPLYING RICHLY MOIST LOW LEVEL INFLOW. 
15-18 DEG C 850 MB DEW POINTS AND LOW-MID 70S SFC DEW POINTS WILL BE
JUXTAPOSED WITH 8-9 DEG C/KM MIDLEVEL LAPSE RATES.  OAX RAOB --
MODIFIED TO REMOVE SINGULAR DEW POINT ERROR AROUND 960 MB -- YIELDS
MLCAPE AROUND 3500 J/KG.  MODIFIED RUC SOUNDINGS SHOW MAX MUCAPES
4000-5000 J/KG.  WITH SUCH LARGE INSTABILITY...AND APPROXIMATELY 50
KT 0-6 KM SHEARS...EXPLOSIVE DEVELOPMENT AND INTENSIFICATION
POSSIBLE.  MEANWHILE...CONVECTIVE COMPLEX INVOF WRN PORTION KS/NEB
BORDER MAY MOVE NEWD INTO RICHER MOISTURE OVER S-CENTRAL/SERN
NEB...LARGE HAIL AND SEVERE WIND POSSIBLE.

..EDWARDS.. 07/07/2003

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

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

40660058 42789832 42879514 42329237 41109255 40759477
40849677 40079839 39970047

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Jul 6, 7:45 PM CDTTornado WatchSPCClay, Dickinson, Lyon, O'Brien, Osceola, Sioux6 hr
Jul 6, 9:20 PM CDTTornado WatchSPCAdair, Adams, Appanoose, Audubon, Boone, Buena Vista and 62 more6 hr
Jul 6, 11:06 PM CDTMesoscale DiscussionSPCAdair, Adams, Appanoose, Audubon, Boone, Buena Vista and 62 more114 min
Jul 7, 1:25 AM CDTMesoscale DiscussionSPCAllamakee, Benton, Black Hawk, Bremer, Buchanan, Butler and 16 more95 min
Jul 7, 2:40 AM CDTSevere Thunderstorm WatchSPCAllamakee, Benton, Black Hawk, Bremer, Buchanan, Chickasaw and 12 more4 hr
Jul 7, 4:22 AM CDTMesoscale DiscussionSPCAllamakee, Black Hawk, Bremer, Buchanan, Chickasaw, Clayton and 5 more83 min
Jul 7, 6:23 AM CDTMesoscale DiscussionSPCCedar, Clinton, Delaware, Dubuque, Iowa, Jackson and 5 more97 min
Jul 7, 12:14 PM CDTMesoscale DiscussionSPCClinton, Des Moines, Lee, Louisa, Muscatine, Scott61 min
Jul 7, 2:35 PM CDTMesoscale DiscussionSPCAllamakee, Clayton, Delaware, Dubuque115 min
Jul 7, 3:30 PM CDTMesoscale DiscussionSPCAdair, Adams, Appanoose, Audubon, Benton, Cass and 31 more3 hr
Jul 7, 3:35 PM CDTSevere Thunderstorm WatchSPCAdair, Adams, Audubon, Benton, Cass, Cedar and 29 more5 hr
Jul 7, 3:52 PM CDTMesoscale DiscussionSPCBanner, Chase, Cheyenne, Deuel, Kimball, Perkins and 1 more2 hr
Jul 7, 4:16 PM CDTMesoscale DiscussionSPCAdams, Arthur, Boone, Buffalo, Butler, Cass and 49 more2 hr
Jul 7, 6:00 PM CDTSevere Thunderstorm WatchSPCArthur, Banner, Box Butte, Chase, Cheyenne, Deuel and 17 more6 hr

Nearby

Mesoscale Discussions in Nebraska, 2003Mesoscale Discussions in Iowa, 2003Every mesoscale discussion in 2003

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.