Alert archive / Nebraska / Mesoscale Discussions in 2018

Mesoscale Discussion 656

June 6, 2018Phillips County, Sedgwick County, Yuma County, Colorado; Cheyenne County, Rawlins County, Kansas; 19 counties in Nebraska

The Storm Prediction Center issued this mesoscale discussion at Jun 6, 2018, 6:59 PM MDT for Phillips County, Sedgwick County, Yuma County, Colorado; Cheyenne County, Rawlins County, Kansas; 19 counties in Nebraska. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: Jun 6, 2018, 6:59 PM MDT (00:59 UTC)
Expired: Jun 6, 2018, 9:00 PM MDT
In force: 2 hr
Issued by: the Storm Prediction Center

All 24 counties

Phillips County, CO, Sedgwick County, CO, Yuma County, CO, Cheyenne County, KS, Rawlins County, KS, Arthur County, NE, Chase County, NE, Cheyenne County, NE, Deuel County, NE, Dundy County, NE, Frontier County, NE, Garden County, NE, Grant County, NE, Hayes County, NE, Hitchcock County, NE, Hooker County, NE, Keith County, NE, Lincoln County, NE, Logan County, NE, McPherson County, NE, Morrill County, NE, Perkins County, NE, Red Willow County, NE, Thomas County, NE

The radar

The Goodland radar (KGLD), 162 km from the middle of the area, began a volume at 01:03 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

N. Platte/Lee Bi, NE (KLBF), launched 00:00Z, 1.0 hours before the alert went out and 117 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: 2094 J/kg
Mixed-layer CIN: -90 J/kg
Mixed-layer LCL: 2401 m above ground
0-6 km bulk shear: 19 kt
0-1 km storm-relative helicity: 28 m²/s²
0-3 km storm-relative helicity: 87 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

519 
ACUS11 KWNS 070100
SWOMCD
SPC MCD 070059 
NEZ000-KSZ000-COZ000-070300-

Mesoscale Discussion 0656
NWS Storm Prediction Center Norman OK
0759 PM CDT Wed Jun 06 2018

Areas affected...Parts of southwest Nebraska...northeast
Colorado...southwest Kansas

Concerning...Severe Thunderstorm Watch 158...

Valid 070059Z - 070300Z

The severe weather threat for Severe Thunderstorm Watch 158
continues.

SUMMARY...Risk for severe hail may continue another couple of hours,
with increasing potential for strong wind gusts developing through
late evening.

DISCUSSION...Perhaps the most prominent convective development is
now centered near Sidney NE, in the form of an upscale growing
cluster of storms.   This is being supported by weak low/mid-level
warm advection, which appears generally focused in corridor east of
the formerly tornadic supercell near Laramie, through areas of
Nebraska to the north of Sidney/Ogalalla and North Platte.  Models
suggest that, as the boundary layer increasingly decouples through
02-04Z, the nose of a strengthening southerly low-level jet (30-40+
kt) will become focused across this region.  This appears likely to
promote further upscale convective growth in the presence of steep
lapse rates and moderate to large CAPE, with the evolution of an
increasing organized mesoscale convective system possible.  Embedded
within light southwesterly deep layer mean flow, east/southeastward
progression will initially be slow, at least until sub-cloud
evaporative cooling supports a sufficiently strong surface cold
pool.

..Kerr.. 06/07/2018

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...GID...LBF...GLD...BOU...CYS...

LAT...LON   41680344 42160209 41860050 41210006 40510013 39720067
            39640162 39780223 40010256 40650290 40900347 41680344

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jun 6, 10:58 PM MDT	Mesoscale Discussion	SPC	Kit Carson, Phillips, Washington, Yuma	2 hr
Jun 6, 7:45 PM MDT	Mesoscale Discussion	SPC	Brown, Marshall, Nemaha, Republic, Washington	90 min
Jun 7, 12:58 AM MDT	Mesoscale Discussion	SPC	Barber, Barton, Clark, Cloud, Comanche, Edwards and 31 more	92 min
Jun 7, 1:25 AM MDT	Severe Thunderstorm Watch	SPC	Barber, Barton, Comanche, Edwards, Ellis, Ellsworth and 22 more	5 hr
Jun 7, 3:35 AM MDT	Mesoscale Discussion	SPC	Barber, Cloud, Comanche, Ellsworth, Harper, Harvey and 17 more	85 min

Nearby

Mesoscale Discussions in Nebraska, 2018 Mesoscale Discussions in Colorado, 2018 Mesoscale Discussions in Kansas, 2018 Every mesoscale discussion in 2018

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.