Alert archive / Nebraska / Mesoscale Discussions in 2004

Mesoscale Discussion 2201

September 13, 20044 states

The Storm Prediction Center issued this mesoscale discussion at Sep 13, 2004, 3:21 PM CDT for 4 states. It was in force for 84 min.

The area

The outline as issued.

The facts

Issued: Sep 13, 2004, 3:21 PM CDT (20:21 UTC)
Expired: Sep 13, 2004, 4:45 PM CDT
In force: 84 min
Issued by: the Storm Prediction Center

All 28 counties

Lyon County, IA, O'Brien County, IA, Osceola County, IA, Plymouth County, IA, Sioux County, IA, Nobles County, MN, Rock County, MN, Antelope County, NE, Boone County, NE, Cedar County, NE, Dakota County, NE, Dixon County, NE, Greeley County, NE, Howard County, NE, Knox County, NE, Madison County, NE, Pierce County, NE, Sherman County, NE, Stanton County, NE, Valley County, NE, Wayne County, NE, Wheeler County, NE, Clay County, SD, Lincoln County, SD, Minnehaha County, SD, Turner County, SD, Union County, SD, Yankton County, SD

The radar

The Sioux Falls radar (KFSD), 148 km from the middle of the area, began a volume at 20:22 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.

Severe Thunderstorm Watch 816Sep 13, 5:50 PM CDT

The nearest sounding before it

Omaha, NE (KOAX), launched 12:00Z, 8.4 hours before the alert went out and 157 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 12 J/kg
Mixed-layer CIN: -643 J/kg
Mixed-layer LCL: 1472 m above ground
0-6 km bulk shear: 22 kt
0-1 km storm-relative helicity: 253 m²/s²
0-3 km storm-relative helicity: 321 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.4

Open this sounding in Storm Lab

The text

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

342 
ACUS11 KWNS 132025
SWOMCD
SPC MCD 132021 
MNZ000-IAZ000-NEZ000-SDZ000-132145-

MESOSCALE DISCUSSION 2201
NWS STORM PREDICTION CENTER NORMAN OK
0321 PM CDT MON SEP 13 2004

AREAS AFFECTED...SERN SD/NWRN IA SWWD INTO NERN/CNTRL NEB

CONCERNING...SEVERE THUNDERSTORM POTENTIAL 

VALID 132021Z - 132145Z

POTENTIAL FOR SURFACE-BASED TSTM DEVELOPMENT APPEARS TO BE
INCREASING WITH INITIATION POSSIBLE BY 21Z. CONDITIONS ARE BEING
MONITORED FOR A POSSIBLE WW.

LATEST VISIBLE SATELLITE IMAGERY SHOWS A DEEPENING CUMULUS FIELD
FROM NEAR YKN SWWD TO NEAR BUB WITHIN ENVIRONMENT CHARACTERIZED BY
TEMPERATURES IN THE UPPER 80S TO LOWER 90S AND DEWPOINTS IN THE 50S.
THOUGH 12Z OBSERVED SOUNDINGS INDICATED THE PRESENCE OF A
SUBSTANTIAL CAP...IT APPEARS THAT STRONG DIABATIC HEATING COUPLED
WITH SUSTAINED CONVERGENCE ALONG PRE-FRONTAL TROUGH /EXTENDING FROM
ERN SD SWWD INTO SWRN NEB/ HAVE LOCALLY REMOVED MUCH OF THE
CONVECTIVE INHIBITION. 

SHOULD STORMS DEVELOP...THE MODERATELY UNSTABLE AIRMASS /I.E.
MLCAPES 1000-1500 J/KG/ IN CONJUNCTION WITH 30-35 KTS OF 0-6KM SHEAR
AND 150-250 M2/S2 0-3 KM SRH /PER NELIGH NEB PROFILER/ SUGGEST THE
POTENTIAL FOR ORGANIZED TSTMS...INCLUDING SUPERCELLS. DEEPLY-MIXED
CHARACTER OF THE BOUNDARY-LAYER SUGGESTS THAT STORMS SHOULD BE
RELATIVELY HIGH-BASED AND CAPABLE OF MAINLY DAMAGING WINDS AND LARGE
HAIL.

CONVECTIVE TRENDS ARE BEING MONITORED AND A WW MAY BE REQUIRED PRIOR
TO 21 OR 2130Z.

..MEAD.. 09/13/2004

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

ATTN...WFO...FSD...OAX...GID...LBF...

41279946 42159865 42759811 43859700 44039590 43449516
42429620 41889696 41039883

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Sep 13, 5:50 PM CDT	Severe Thunderstorm Watch	SPC	Buena Vista, Cherokee, Clay, Dickinson, Emmet, Ida and 8 more	7 hr
Sep 13, 6:12 PM CDT	Mesoscale Discussion	SPC	Becker, Beltrami, Clay, Clearwater, Hubbard, Kittson and 8 more	63 min
Sep 13, 6:55 PM CDT	Severe Thunderstorm Watch	SPC	Becker, Beltrami, Cass, Clay, Clearwater, Hubbard and 11 more	5 hr

Nearby

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