Alert archive / Nebraska / Mesoscale Discussions in 2012

Mesoscale Discussion 1679

August 1, 201223 counties in Nebraska; 4 counties in South Dakota

The Storm Prediction Center issued this mesoscale discussion at Aug 1, 2012, 8:19 PM CDT for 23 counties in Nebraska; 4 counties in South Dakota. It was in force for 56 min.

The area

The outline as issued.

The facts

Issued: Aug 1, 2012, 8:19 PM CDT (01:19 UTC)
Expired: Aug 1, 2012, 9:15 PM CDT
In force: 56 min
Issued by: the Storm Prediction Center
Chance of a watch: 20%

All 27 counties

Antelope County, NE, Boone County, NE, Boyd County, NE, Cedar County, NE, Colfax County, NE, Cuming County, NE, Dakota County, NE, Dixon County, NE, Garfield County, NE, Greeley County, NE, Holt County, NE, Knox County, NE, Loup County, NE, Madison County, NE, Nance County, NE, Pierce County, NE, Platte County, NE, Rock County, NE, Stanton County, NE, Thurston County, NE, Valley County, NE, Wayne County, NE, Wheeler County, NE, Bon Homme County, SD, Clay County, SD, Union County, SD, Yankton County, SD

The radar

The Sioux Falls radar (KFSD), 172 km from the middle of the area, began a volume at 01:21 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 00:00Z, 1.3 hours before the alert went out and 193 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: 7 J/kg
Mixed-layer CIN: -190 J/kg
Mixed-layer LCL: 2779 m above ground
0-6 km bulk shear: 29 kt
0-1 km storm-relative helicity: -6 m²/s²
0-3 km storm-relative helicity: 17 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.

069 
ACUS11 KWNS 020119
SWOMCD
SPC MCD 020119 
IAZ000-NEZ000-SDZ000-020215-

MESOSCALE DISCUSSION 1679
NWS STORM PREDICTION CENTER NORMAN OK
0819 PM CDT WED AUG 01 2012

AREAS AFFECTED...SERN SD...NERN NEB

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY 

VALID 020119Z - 020215Z

PROBABILITY OF WATCH ISSUANCE...20 PERCENT

SUMMARY...CLUSTERS OF STG/SVR TSTMS MAY CONTINUE A THREAT OF
DAMAGING WINDS THROUGH 02Z. THE POTENTIAL FOR A LONGER-LIVED SVR
POTENTIAL IS UNCERTAIN HOWEVER TRENDS WILL CONTINUE TO BE MONITORED.

DISCUSSION...CLUSTERS OF STG/SVR TSTMS NORTH AND SW OF KONL HAVE
DEVELOPED PRONOUNCED BOWING SEGMENTS OVER THE PAST HOUR...HOWEVER
RADAR TRENDS FROM KLNX AND KFSD SUGGEST THE OUTFLOW HAS SURGED
QUICKLY EWD. THIS...COMBINED WITH INCREASING CINH AS RELATIVELY
DRIER AIR IN ADVANCE OF THESE TSTMS COOLS WITH THE LOSS OF DAYTIME
HEATING...SUGGESTS THAT THESE CLUSTERS WILL NOT POSE A LONGER-TERM
SVR THREAT AND THEREFORE A WW IS NOT LIKELY ATTM. HOWEVER...TRENDS
WILL CONTINUE TO BE MONITORED.

..BUNTING/HART.. 08/02/2012

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

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

LAT...LON   42849927 43009905 43199875 43199813 43129704 42979669
            42669647 42189633 41819658 41399733 41329841 41349968
            41850004 42909916 42849927

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Aug 1, 11:08 PM CDT	Mesoscale Discussion	SPC	Adams, Buffalo, Clay, Fillmore, Franklin, Furnas and 13 more	2 hr
Aug 2, 5:37 PM CDT	Mesoscale Discussion	SPC	Arthur, Buffalo, Custer, Dawson, Deuel, Garden and 12 more	83 min
Aug 1, 7:35 PM CDT	Mesoscale Discussion	SPC	Brookings, Codington, Deuel, Grant, Hamlin, Kingsbury and 3 more	55 min
Aug 2, 2:44 PM CDT	Mesoscale Discussion	SPC	Butte, Harding, Lawrence, Meade, Perkins	31 min
Aug 2, 3:03 PM CDT	Severe Thunderstorm Watch	SPC	Butte, Harding, Lawrence, Meade, Perkins	7 hr

Nearby

Mesoscale Discussions in Nebraska, 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.