Mesoscale Discussion 440

Issued

Apr 27, 2021, 6:16 PM MDT (00:16 UTC)

Expired

Apr 27, 2021, 8:15 PM MDT

In force

119 min

Issued by

the Storm Prediction Center

Concerning

Severe thunderstorm watch 112...114

Counties Kit Carson County, CO, Phillips County, CO, Yuma County, CO, Cheyenne County, KS, Decatur County, KS, Rawlins County, KS, Sherman County, KS, Thomas County, KS, Chase County, NE, Dundy County, NE, Frontier County, NE, Furnas County, NE, Gosper County, NE, Hayes County, NE, Hitchcock County, NE, Lincoln County, NE, Perkins County, NE, Red Willow County, NE

The Goodland radar (KGLD), 79 km from the middle of the area, began a volume at 00:15 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.

531 
ACUS11 KWNS 280016
SWOMCD
SPC MCD 280016 
NEZ000-KSZ000-COZ000-280215-

Mesoscale Discussion 0440
NWS Storm Prediction Center Norman OK
0716 PM CDT Tue Apr 27 2021

Areas affected...Northeast Colorado...Southwest Nebraska...and
Northwest Kansas

Concerning...Severe Thunderstorm Watch 112...114...

Valid 280016Z - 280215Z

The severe weather threat for Severe Thunderstorm Watch 112, 114
continues.

SUMMARY...The threat for severe wind and hail will continue across
far northeast Colorado and into adjacent areas of southwest Nebraska
and northwest Kansas through the evening hours.

DISCUSSION...Satellite and radar trends over the past hour have
shown gradual upscale growth from discrete/semi-discrete storms into
a more linear storm mode due to destructive storm interactions and
conglomeration of cold pools. Velocity data from KGLD supports this
idea with a more unified outflow boundary associated with the main
convective cluster becoming apparent. Satellite imagery continues to
show robust updraft pulses within the evolving line, and flash rates
have maintained intensity as storms move into a more favorable
thermodynamic environment. The continued organization of the cold
pool within a strongly sheared environment (50-60 knots of effective
bulk shear and 40 knots of 0-3 km shear) will support the potential
for an organized wind threat, and possibly a bowing segment, as
storms continue to move to the east/northeast through 04 UTC. While
damaging winds will become the main threat, stronger updraft pulses
will be capable of producing severe hail within the line. A brief
tornado remains possible given increasing low-level helicity and
strong low-level bulk shear (per RAP mesoanalysis and the KGLD VWP),
but increasing SBCIN and a linear storm mode cast some uncertainty
into the tornado potential heading into the late evening hours.

..Moore.. 04/28/2021

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

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

LAT...LON   39000273 39730290 40370287 40940181 41290089 41150040
            40839993 40259970 39590003 39260069 38990172 39000273

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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.