Alert archive / South Dakota / Mesoscale Discussions in 2004
Mesoscale Discussion 1817
The Storm Prediction Center issued this mesoscale discussion at Aug 1, 2004, 1:48 PM CDT for 4 states. It was in force for 117 min.
The area
The outline as issued.
The facts
- Issued
- Aug 1, 2004, 1:48 PM CDT (18:48 UTC)
- Expired
- Aug 1, 2004, 3:45 PM CDT
- In force
- 117 min
- Issued by
- the Storm Prediction Center
All 85 counties
Buena Vista County, IA, Calhoun County, IA, Carroll County, IA, Cherokee County, IA, Clay County, IA, Crawford County, IA, Dickinson County, IA, Emmet County, IA, Greene County, IA, Humboldt County, IA, Ida County, IA, Kossuth County, IA, Lyon County, IA, Monona County, IA, O'Brien County, IA, Osceola County, IA, Palo Alto County, IA, Plymouth County, IA, Pocahontas County, IA, Sac County, IA, Sioux County, IA, Webster County, IA, Woodbury County, IA, Big Stone County, MN, Brown County, MN, Chippewa County, MN, Cottonwood County, MN, Jackson County, MN, Kandiyohi County, MN, Lac qui Parle County, MN, Lincoln County, MN, Lyon County, MN, Martin County, MN, McLeod County, MN, Meeker County, MN, Murray County, MN, Nicollet County, MN, Nobles County, MN, Pipestone County, MN, Pope County, MN, Redwood County, MN, Renville County, MN, Rock County, MN, Sibley County, MN, Stearns County, MN, Stevens County, MN, Swift County, MN, Watonwan County, MN, Yellow Medicine County, MN, Cedar County, NE, Dakota County, NE, Dixon County, NE, Knox County, NE, Pierce County, NE, Thurston County, NE, Wayne County, NE, Beadle County, SD, Bon Homme County, SD, Brookings County, SD, Brown County, SD, Clark County, SD, Clay County, SD, Codington County, SD, Davison County, SD, Day County, SD, Deuel County, SD, Douglas County, SD, Grant County, SD, Hamlin County, SD, Hanson County, SD, Hutchinson County, SD, Kingsbury County, SD, Lake County, SD, Lincoln County, SD, Marshall County, SD, McCook County, SD, Miner County, SD, Minnehaha County, SD, Moody County, SD, Roberts County, SD, Sanborn County, SD, Spink County, SD, Turner County, SD, Union County, SD, Yankton County, SD
The radar
The Sioux Falls radar (KFSD), 63 km from the middle of the area, began a volume at 18:49 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
Aberdeen, SD (KABR), launched 12:00Z, 6.8 hours before the alert went out and 179 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
- 319 J/kg
- Mixed-layer CIN
- -316 J/kg
- Mixed-layer LCL
- 1777 m above ground
- 0-6 km bulk shear
- 30 kt
- 0-1 km storm-relative helicity
- 10 m²/s²
- 0-3 km storm-relative helicity
- 155 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted, in the capitals the NWS used until 2016.
200 ACUS11 KWNS 011849 SWOMCD SPC MCD 011848 MNZ000-IAZ000-NEZ000-SDZ000-012045- MESOSCALE DISCUSSION 1817 NWS STORM PREDICTION CENTER NORMAN OK 0148 PM CDT SUN AUG 01 2004 AREAS AFFECTED...ERN SD/SWRN MN/NERN NEB/NWRN IA CONCERNING...SEVERE THUNDERSTORM POTENTIAL VALID 011848Z - 012045Z TORNADO WATCH LIKELY WILL BE ISSUED FOR PORTIONS OF ERN SD...SWRN MN ...NERN NEB AND NWRN IA WITHIN THE NEXT 1 TO 2 HOURS. OUTFLOW BOUNDARY FROM EARLIER CONVECTION EXTENDS FROM DSM TO SOUTH OF SUX...AND THEN NWWD INTO CENTRAL SD TO A LOW PRESSURE SYSTEM NEAR PIR. A WEAK COLD FRONT ALSO WAS PUSHING SLOWLY SWD AND EXTENDED FROM THE SURFACE LOW IN CENTRAL SD NEWD INTO NRN MN. THE AIR MASS BETWEEN THESE TWO BOUNDARIES HAS BECOME STRONGLY UNSTABLE WITH MLCAPES APPROACHING 3000 J/KG...AND WILL CONTINUE DESTABILIZING WITH ADDITIONAL HEATING. SATELLITE IMAGERY SUGGESTS A SHORTWAVE TROUGH IS MOVING EWD INTO THE CENTRAL DAKOTAS. THE ABR 18Z SOUNDING SHOWS THE CAP HAS WEAKENED CONSIDERABLY SINCE THE 12 RUN. THE CAPPING INVERSION SHOULD CONTINUE ERODING DURING THE NEXT COUPLE OF HOURS AS THE UPPER TROUGH NEARS THE AREA. GIVEN THE STRONG INSTABILITY AND DEEP LAYER SHEAR AT 45 KT...ONCE STORMS DEVELOP...THEY SHOULD EVOLVE QUICKLY INTO SUPERCELLS. HAIL 3 INCHES OR LARGER WILL BE THE MAIN THREAT...BUT THE BACKED BOUNDARY LAYER WINDS NORTH OF THE OUTFLOW BOUNDARY SHOULD PROVIDE SUFFICIENT LOW LEVEL SHEAR FOR A FEW TORNADOES. ..IMY.. 08/01/2004 ...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT... ATTN...WFO...MPX...DMX...FGF...FSD...OAX...ABR... 43829844 45739847 45789742 45719448 44829424 43349404 41659424 42349817
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 31, 8:19 PM CDT | Mesoscale Discussion | SPC | Dickinson, Emmet, Lyon, Osceola, Winnebago | 56 min |
| Jul 31, 9:45 PM CDT | Severe Thunderstorm Watch | SPC | Buena Vista, Cherokee, Clay, Dickinson, Emmet, Hancock and 10 more | 5 hr |
| Jul 31, 11:41 PM CDT | Mesoscale Discussion | SPC | Buena Vista, Calhoun, Cerro Gordo, Cherokee, Chickasaw, Clay and 19 more | 64 min |
| Aug 1, 1:59 AM CDT | Mesoscale Discussion | SPC | Adair, Adams, Audubon, Boone, Carroll, Cass and 24 more | 91 min |
| Aug 1, 5:56 AM CDT | Mesoscale Discussion | SPC | Adair, Adams, Appanoose, Audubon, Boone, Bremer and 59 more | 94 min |
| Aug 1, 12:11 PM CDT | Mesoscale Discussion | SPC | Buena Vista, Calhoun, Carroll, Cherokee, Crawford, Greene and 3 more | 64 min |
| Aug 1, 2:17 PM CDT | Mesoscale Discussion | SPC | Adair, Adams, Audubon, Cass, Clarke, Dallas and 15 more | 58 min |
| Aug 1, 3:15 PM CDT | Tornado Watch | SPC | Big Stone, Brown, Chippewa, Cottonwood, Douglas, Grant and 21 more | 7 hr |
| Aug 1, 3:41 PM CDT | Mesoscale Discussion | SPC | Kanabec, Mille Lacs, Morrison, Pine | 2 hr |
| Aug 1, 4:00 PM CDT | Severe Thunderstorm Watch | SPC | Aitkin, Benton, Chisago, Crow Wing, Isanti, Kanabec and 3 more | 5 hr |
| Jul 31, 10:27 PM CDT | Mesoscale Discussion | SPC | Antelope, Boyd, Brown, Cedar, Cherry, Holt and 5 more | 93 min |
| Aug 1, 6:35 PM CDT | Severe Thunderstorm Watch | SPC | Brown, Campbell, Corson, Dewey, Edmunds, Faulk and 4 more | 3 hr |
Nearby
Mesoscale Discussions in South Dakota, 2004Mesoscale Discussions in Minnesota, 2004Mesoscale 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.