Alert archive / Nebraska / Mesoscale Discussions in 2012

Mesoscale Discussion 695

May 4, 20124 states

The Storm Prediction Center issued this mesoscale discussion at May 4, 2012, 1:50 PM CDT for 4 states. It was in force for 25 min.

The area

The outline as issued.

The facts

Issued: May 4, 2012, 1:50 PM CDT (18:50 UTC)
Expired: May 4, 2012, 2:15 PM CDT
In force: 25 min
Issued by: the Storm Prediction Center
Chance of a watch: 95%

All 42 counties

Buena Vista County, IA, Cherokee County, IA, Clay County, IA, Dickinson County, IA, Emmet County, IA, Ida County, IA, Lyon County, IA, O'Brien County, IA, Osceola County, IA, Palo Alto County, IA, Plymouth County, IA, Sioux County, IA, Woodbury County, IA, Cottonwood County, MN, Jackson County, MN, Martin County, MN, Murray County, MN, Nobles County, MN, Rock County, MN, Antelope County, NE, Boyd County, NE, Cedar County, NE, Dakota County, NE, Dixon County, NE, Garfield County, NE, Holt County, NE, Knox County, NE, Madison County, NE, Pierce County, NE, Rock County, NE, Stanton County, NE, Thurston County, NE, Wayne County, NE, Wheeler County, NE, Bon Homme County, SD, Clay County, SD, Hutchinson County, SD, Lincoln County, SD, Minnehaha County, SD, Turner County, SD, Union County, SD, Yankton County, SD

The radar

The Sioux Falls radar (KFSD), 103 km from the middle of the area, began a volume at 18:53 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, 6.8 hours before the alert went out and 187 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: 2705 J/kg
Mixed-layer CIN: -17 J/kg
Mixed-layer LCL: 584 m above ground
0-6 km bulk shear: 17 kt
0-1 km storm-relative helicity: 10 m²/s²
0-3 km storm-relative helicity: 98 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.

068 
ACUS11 KWNS 041851
SWOMCD
SPC MCD 041850
IAZ000-MNZ000-NEZ000-SDZ000-041915-

MESOSCALE DISCUSSION 0695
NWS STORM PREDICTION CENTER NORMAN OK
0150 PM CDT FRI MAY 04 2012

AREAS AFFECTED...SERN SD...NERN NEB...SWRN MN...NWRN IA

CONCERNING...SEVERE POTENTIAL...WATCH NEEDED SOON

VALID 041850Z - 041915Z

PROBABILITY OF WATCH ISSUANCE...95 PERCENT

SUMMARY...A SEVERE THUNDERSTORM WATCH WILL BE ISSUED SOON FROM NERN
NEB INTO SWRN MN...INCLUDING PARTS OF SERN SD AND NWRN IA.

DISCUSSION...ENVIRONMENTAL CONDITIONS HAVE BECOME FAVORABLE FOR
SEVERE STORMS AND A WATCH ISSUANCE WILL BE COORDINATED BETWEEN THE
SPC AND THE AFFECTED LOCAL NATIONAL WEATHER SERVICE OFFICES SHORTLY.


STRONG BOUNDARY LAYER HEATING HAS CONTRIBUTED TO STEEPENING LOW
LEVEL LAPSE RATES ALONG AN AXIS FROM NERN NEB INTO SWRN MN.  THIS
AXIS OF HIGHER INSTABILITY WILL PROVE FAVORABLE FOR UPWARD GROWTH OF
ONGOING TSTM ACTIVITY AND LARGE HAIL AND DAMAGING WINDS ARE POSSIBLE
WITH THIS CONVECTION.

..DARROW/MEAD.. 05/04/2012

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

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

LAT...LON   42740000 44169562 43539373 42079596 41629926 42740000

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 3, 7:09 PM CDT	Tornado Watch	SPC	Adair, Adams, Appanoose, Cass, Cedar, Clarke and 23 more	6 hr
May 3, 11:18 PM CDT	Mesoscale Discussion	SPC	Adair, Adams, Appanoose, Cass, Cedar, Clarke and 23 more	27 min
May 4, 12:53 AM CDT	Severe Thunderstorm Watch	SPC	Des Moines, Henry, Jefferson, Lee, Van Buren	4 hr
May 4, 2:16 AM CDT	Mesoscale Discussion	SPC	Appanoose, Davis, Decatur, Des Moines, Henry, Jefferson and 9 more	119 min
May 4, 2:00 PM CDT	Severe Thunderstorm Watch	SPC	Buena Vista, Calhoun, Carroll, Cerro Gordo, Cherokee, Clay and 23 more	9 hr
May 4, 3:52 PM CDT	Mesoscale Discussion	SPC	Buena Vista, Cerro Gordo, Cherokee, Clay, Dickinson, Emmet and 17 more	53 min
May 4, 5:31 PM CDT	Mesoscale Discussion	SPC	Audubon, Benton, Black Hawk, Boone, Bremer, Buchanan and 66 more	29 min
May 4, 5:52 PM CDT	Severe Thunderstorm Watch	SPC	Fremont, Harrison, Mills, Monona, Montgomery, Page and 2 more	5 hr
May 4, 6:01 PM CDT	Severe Thunderstorm Watch	SPC	Benton, Black Hawk, Boone, Bremer, Buchanan, Butler and 22 more	3 hr
May 4, 6:49 AM CDT	Mesoscale Discussion	SPC	Antelope, Boyd, Cedar, Dixon, Holt, Keya Paha and 5 more	116 min

Nearby

Mesoscale Discussions in Nebraska, 2012 Mesoscale Discussions in Iowa, 2012 Mesoscale Discussions in South Dakota, 2012 Every mesoscale discussion in 2012

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.