Alert archive / Iowa / Mesoscale Discussions in 2004
Mesoscale Discussion 2021
The Storm Prediction Center issued this mesoscale discussion at Aug 16, 2004, 6:49 PM CDT for 25 counties in Iowa. It was in force for 116 min.
The area
The outline as issued.
The facts
- Issued
- Aug 16, 2004, 6:49 PM CDT (23:49 UTC)
- Expired
- Aug 16, 2004, 8:45 PM CDT
- In force
- 116 min
- Issued by
- the Storm Prediction Center
All 25 counties
Boone County, IA, Buena Vista County, IA, Butler County, IA, Calhoun County, IA, Carroll County, IA, Dallas County, IA, Franklin County, IA, Greene County, IA, Grundy County, IA, Guthrie County, IA, Hamilton County, IA, Hardin County, IA, Humboldt County, IA, Ida County, IA, Jasper County, IA, Marshall County, IA, Pocahontas County, IA, Polk County, IA, Poweshiek County, IA, Sac County, IA, Story County, IA, Tama County, IA, Warren County, IA, Webster County, IA, Wright County, IA
The radar
The Des Moines radar (KDMX), 64 km from the middle of the area, began a volume at 23:51 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 nearest sounding before it
Omaha, NE (KOAX), launched 12:00Z, 11.8 hours before the alert went out and 212 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.
- Mixed-layer CAPE
- 24 J/kg
- Mixed-layer CIN
- -295 J/kg
- Mixed-layer LCL
- 981 m above ground
- 0-6 km bulk shear
- 30 kt
- 0-1 km storm-relative helicity
- 85 m²/s²
- 0-3 km storm-relative helicity
- 189 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.1
The text
As transmitted, in the capitals the NWS used until 2016.
737 ACUS11 KWNS 162349 SWOMCD SPC MCD 162349 IAZ000-170145- MESOSCALE DISCUSSION 2021 NWS STORM PREDICTION CENTER NORMAN OK 0649 PM CDT MON AUG 16 2004 AREAS AFFECTED...IA CONCERNING...SEVERE THUNDERSTORM WATCH 755... VALID 162349Z - 170145Z CONTINUE WW. VIGOROUS THUNDERSTORM ACTIVITY IS ONGOING. MOST INTENSE STORMS HAVE BEEN SOUTH OF MASON CITY...WHERE LOW-LEVEL WARM ADVECTION WAS MAXIMIZED ALONG THERMAL GRADIENT TO THE EAST SOUTHEAST OF SURFACE LOW...NOW NORTH OF SIOUX CITY. HOWEVER...MORE RECENT CONVECTIVE DEVELOPMENT HAS TAKEN PLACE UPSTREAM TOWARD SURFACE LOW...SUPPORTED BY FORCED ASCENT OF BOUNDARY LAYER WITH MEAN MIXED LAYER CAPE AROUND 2000 J/KG. FURTHER INCREASE/INTENSIFICATION OF THUNDERSTORMS APPEARS LIKELY IN THIS ENVIRONMENT ACROSS NORTHWEST/CENTRAL IOWA DURING THE NEXT COUPLE OF HOURS. NORTHWESTERLY MID-LEVEL FLOW REGIME AND ASSOCIATED SHEAR ARE RATHER WEAK...BUT THERMODYNAMIC ENVIRONMENT WILL REMAIN SUPPORTIVE OF LARGE HAIL/DAMAGING WIND GUSTS INTO THE EVENING HOURS. ..KERR.. 08/16/2004 ...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT... ATTN...WFO...DMX...FSD... 42879538 43149436 42869282 42249258 41739233 41399288 41269381 41579464 42049525 42529588
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 15, 7:14 PM CDT | Mesoscale Discussion | SPC | Dickinson, Lyon, Osceola, Sioux | 2 hr |
| Aug 16, 4:03 PM CDT | Mesoscale Discussion | SPC | Buena Vista, Cherokee, Clay, Crawford, Dickinson, Harrison and 9 more | 57 min |
| Aug 16, 5:30 PM CDT | Severe Thunderstorm Watch | SPC | Audubon, Boone, Buena Vista, Calhoun, Carroll, Cerro Gordo and 34 more | 6 hr |
Nearby
Mesoscale Discussions in Iowa, 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.