Alert archive / South Dakota / Mesoscale Discussions in 2021

Mesoscale Discussion 149

March 10, 20215 counties in Nebraska; 7 counties in South Dakota; 6 counties in Wyoming

The Storm Prediction Center issued this mesoscale discussion at Mar 10, 2021, 12:12 AM MST for 5 counties in Nebraska; 7 counties in South Dakota; 6 counties in Wyoming. It was in force for 6 hr.

The area

The outline as issued.

The facts

Issued: Mar 10, 2021, 12:12 AM MST (07:12 UTC)
Expired: Mar 10, 2021, 6:15 AM MST
In force: 6 hr
Issued by: the Storm Prediction Center
Concerning: Heavy snow

Counties Box Butte County, NE, Dawes County, NE, Scotts Bluff County, NE, Sheridan County, NE, Sioux County, NE, Bennett County, SD, Custer County, SD, Fall River County, SD, Haakon County, SD, Jackson County, SD, Oglala Lakota County, SD, Pennington County, SD, Albany County, WY, Converse County, WY, Goshen County, WY, Niobrara County, WY, Platte County, WY, Weston County, WY

The radar

The Rapid City radar (KUDX), 173 km from the middle of the area, began a volume at 07:13 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

Rapid City, SD (KUNR), launched 00:00Z, 7.2 hours before the alert went out and 166 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 1903 m above ground
0-6 km bulk shear: 74 kt
0-1 km storm-relative helicity: -21 m²/s²
0-3 km storm-relative helicity: 107 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

757 
ACUS11 KWNS 100713
SWOMCD
SPC MCD 100712 
SDZ000-NEZ000-WYZ000-101315-

Mesoscale Discussion 0149
NWS Storm Prediction Center Norman OK
0112 AM CST Wed Mar 10 2021

Areas affected...East-Central WY...Southwest SD...Northwest NE
Panhandle

Concerning...Heavy snow 

Valid 100712Z - 101315Z

SUMMARY...Heavy snow is possible across east-central WY, southwest
SD, and the northwest NE Panhandle over the next several hours.

DISCUSSION...Regional radar imagery has shown increase organization
within the frontogenetic band currently extending from far southeast
WY across the extreme northwest NE Panhandle and into southwest SD.
Persistent precipitation and resultant wet-bulbing within this band
will likely lead to a transition from light rainfall to
moderate/occasionally heavy snow. Snowfall rates around 1" per hour
are possible. 

In addition to this band, broad ascent attendant to shortwave
trough/developing low-level low will continue to spread over the
region. This will contribute to a broadening precipitation field
across east-central WY, with some instances of moderate to heavy
snow (i.e. 1"/hr) possible.

..Mosier.. 03/10/2021

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

ATTN...WFO...ABR...LBF...UNR...CYS...RIW...

LAT...LON   41560648 43700616 44550253 44190108 42960154 41410413
            41560648

Nearby

Mesoscale Discussions in South Dakota, 2021 Mesoscale Discussions in Wyoming, 2021 Mesoscale Discussions in Nebraska, 2021 Every mesoscale discussion in 2021

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.