Alert archive / Montana / Mesoscale Discussions in 2014

Mesoscale Discussion 751

May 28, 201430 counties in Montana; Divide County, North Dakota; Sheridan County, Wyoming

The Storm Prediction Center issued this mesoscale discussion at May 28, 2014, 6:28 PM MDT for 30 counties in Montana; Divide County, North Dakota; Sheridan County, Wyoming. It was in force for 92 min.

The area

The outline as issued.

The facts

Issued: May 28, 2014, 6:28 PM MDT (00:28 UTC)
Expired: May 28, 2014, 8:00 PM MDT
In force: 92 min
Issued by: the Storm Prediction Center

All 32 counties

Big Horn County, MT, Blaine County, MT, Carbon County, MT, Chouteau County, MT, Custer County, MT, Daniels County, MT, Dawson County, MT, Fallon County, MT, Fergus County, MT, Garfield County, MT, Golden Valley County, MT, Judith Basin County, MT, McCone County, MT, Meagher County, MT, Musselshell County, MT, Petroleum County, MT, Phillips County, MT, Powder River County, MT, Prairie County, MT, Richland County, MT, Roosevelt County, MT, Rosebud County, MT, Sheridan County, MT, Stillwater County, MT, Sweet Grass County, MT, Treasure County, MT, Valley County, MT, Wheatland County, MT, Wibaux County, MT, Yellowstone County, MT, Divide County, ND, Sheridan County, WY

The radar

The Billings radar (KBLX), 81 km from the middle of the area, began a volume at 00:31 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

Great_falls, MT (KTFX), launched 00:00Z, 0.5 hours before the alert went out and 209 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: 1475 m above ground
0-6 km bulk shear: 61 kt
0-1 km storm-relative helicity: -92 m²/s²
0-3 km storm-relative helicity: 164 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.

402 
ACUS11 KWNS 290028
SWOMCD
SPC MCD 290028 
NDZ000-MTZ000-WYZ000-290200-

MESOSCALE DISCUSSION 0751
NWS STORM PREDICTION CENTER NORMAN OK
0728 PM CDT WED MAY 28 2014

AREAS AFFECTED...CENTRAL AND ERN MT/NRN WY

CONCERNING...SEVERE THUNDERSTORM WATCH 196...197...

VALID 290028Z - 290200Z

THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH
196...197...CONTINUES.

SUMMARY...RISK FOR DAMAGING WINDS AND HAIL CONTINUES ACROSS CENTRAL
AND ERN MT AND ADJACENT NRN WY...WITH THE GREATEST RISK FOR DAMAGING
WINDS APPARENT ACROSS N CENTRAL MT ATTM.  WIND PROBABILITY WITHIN
THE SPC 01Z OUTLOOK WILL BE INCREASED TO REFLECT THE EVOLVING SEVERE
RISK ACROSS N CENTRAL AND NERN MT.

DISCUSSION...LATEST RADAR LOOP SHOWS TWO MAIN CLUSTERS OF STORMS
ATTM -- ONE ACROSS E CENTRAL MT AND A SECOND OVER N CENTRAL MT
MOVING ENEWD AWAY FROM THE GTF VICINITY ATTM.  BOTH CLUSTERS OF
STORMS ARE MOVING INTO A FAVORABLE THERMODYNAMIC ENVIRONMENT...WHERE
ESELY LOW-LEVEL FLOW CONTINUES TO ADVECT LOW 60S DEWPOINTS INTO ERN
AND NRN MT ATTM.  THUS...SEVERE RISK REMAINS APPARENT ACROSS THIS
REGION.

THE STORMS OVER N CENTRAL MT -- INVOF AN ADVANCING COLD FRONT AND
WITHIN THE ZONE OF STRONGEST DEEP-LAYER SHEAR AHEAD OF THE MAIN
UPPER TROUGH -- HAVE BECOME PARTICULARLY ORGANIZED...SHOWING
TENDENCY FOR BOTH BOWING STRUCTURES AND SUPERCELL CHARACTERISTICS. 
ALONG WITH RISK FOR LARGE HAIL...DAMAGING WIND POTENTIAL MAY
INCREASE FURTHER IN THE NEAR TERM AS SOME POTENTIAL FOR UPSCALE
GROWTH INTO A BOWING MCS IS EVIDENT.  GREATEST LIKELIHOOD FOR THE
MOST SUBSTANTIAL/WIDESPREAD SEVERE WEATHER WILL EXIST OVER THE NEXT
3-4 HOURS...AFTER WHICH THE DIURNALLY STABILIZING BOUNDARY LAYER
WILL YIELD A GRADUAL DECREASE IN CONVECTIVE INTENSITY/SEVERE RISK.

..GOSS.. 05/29/2014

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

ATTN...WFO...BIS...UNR...BYZ...GGW...RIW...TFX...

LAT...LON   44740957 45671059 46581128 48181081 49050896 49040342
            46480415 44290555 44740957

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 28, 8:21 PM MDT	Mesoscale Discussion	SPC	Blaine, Custer, Daniels, Dawson, Fallon, Garfield and 10 more	114 min
May 29, 2:15 PM MDT	Mesoscale Discussion	SPC	Adams, Billings, Bottineau, Bowman, Burke, Dunn and 14 more	60 min
May 29, 2:45 PM MDT	Severe Thunderstorm Watch	SPC	Adams, Billings, Bottineau, Bowman, Burke, Burleigh and 15 more	6 hr
May 29, 5:25 PM MDT	Mesoscale Discussion	SPC	Adams, Billings, Bottineau, Bowman, Burke, Dunn and 12 more	65 min
May 29, 1:54 PM MDT	Mesoscale Discussion	SPC	Campbell, Converse, Fremont, Goshen, Hot Springs, Johnson and 6 more	96 min

Nearby

Mesoscale Discussions in Montana, 2014 Mesoscale Discussions in North Dakota, 2014 Mesoscale Discussions in Wyoming, 2014 Every mesoscale discussion in 2014

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.