Alert archive / Montana / Mesoscale Discussions in 2011

Mesoscale Discussion 1981

August 14, 201112 counties in Montana; 4 counties in North Dakota; Harding County, South Dakota

The Storm Prediction Center issued this mesoscale discussion at Aug 14, 2011, 5:56 PM MDT for 12 counties in Montana; 4 counties in North Dakota; Harding County, South Dakota. It was in force for 94 min.

The area

The outline as issued.

The facts

Issued
Aug 14, 2011, 5:56 PM MDT (23:56 UTC)
Expired
Aug 14, 2011, 7:30 PM MDT
In force
94 min
Issued by
the Storm Prediction Center

Counties Carter County, MT, Custer County, MT, Daniels County, MT, Dawson County, MT, Fallon County, MT, McCone County, MT, Powder River County, MT, Prairie County, MT, Richland County, MT, Roosevelt County, MT, Sheridan County, MT, Wibaux County, MT, Billings County, ND, Bowman County, ND, Golden Valley County, ND, Slope County, ND, Harding County, SD

The radar

The Glasgow radar (KGGW), 169 km from the middle of the area, began a volume at 23:56 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

Glasgow Intl Airport, MT (KGGW), launched 12:00Z, 11.9 hours before the alert went out and 169 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-pSkew-T log-p diagram, Glasgow Intl Airport, MT at 12:00Z on 2011-08-14Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 16 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Glasgow Intl Airport, MT at 12:00Z on 2011-08-14The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 122 square meters per square second.19395878Sfc1 km3 km6 km9 kmRMLM
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
16 J/kg
Mixed-layer CIN
-468 J/kg
Mixed-layer LCL
2489 m above ground
0-6 km bulk shear
40 kt
0-1 km storm-relative helicity
122 m²/s²
0-3 km storm-relative helicity
150 m²/s²
Significant tornado parameter
0.0
Supercell composite
-0.1

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

722 
ACUS11 KWNS 142357
SWOMCD
SPC MCD 142356
NDZ000-SDZ000-MTZ000-WYZ000-150130-

MESOSCALE DISCUSSION 1981
NWS STORM PREDICTION CENTER NORMAN OK
0656 PM CDT SUN AUG 14 2011

AREAS AFFECTED...ERN MT INTO FAR WRN ND/NWRN SD

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 142356Z - 150130Z

ISOLATED STORMS WILL CONTINUE INTO THE EVENING. STRONG WIND GUSTS
AND HAIL WILL BE POSSIBLE WITH THE STRONGEST STORMS. GIVEN THE
ISOLATED NATURE OF CONVECTION HOWEVER...A WW IS NOT ANTICIPATED AT
THIS TIME.

ISOLATED STORMS WERE IN PROGRESS NEAR THE MT/SK BORDER...FORCED IN
PART BY AN EXITING VORTICITY MAX ACROSS SRN SK. FURTHER S ACROSS
SERN MT...ANOTHER STORM OR TWO HAD DEVELOPED ALONG A SFC TROUGH
AHEAD OF ANOTHER APPROACHING VORTICITY MAX ACROSS NERN WY. LATEST
VIS SAT IMAGERY SHOWED SOME DEVELOPMENT OF THE CUMULUS FIELD ALONG
THE SURFACE TROUGH ACROSS ERN MT LATE THIS AFTERNOON. WHILE THE
ENVIRONMENT WAS MODERATELY UNSTABLE /MLCAPE AROUND 1500-2000
J/KG/...A STRONG CAP IS LIKELY PROHIBITING MORE WIDESPREAD/ROBUST
CONVECTIVE DEVELOPMENT. ANY STORMS THAT DO DEVELOP WILL REMAIN
ELEVATED AND STRUGGLE TO OVERCOME THE STRONG CAP. HOWEVER...GIVEN
THE MODERATE INSTABILITY...ADEQUATE DEEP LAYER SHEAR /EFFECTIVE BULK
SHEAR 30-45 KT/ AND STEEP LAPSE RATES...ANY STRONGER CELL THAT CAN
OVERCOME THE CAP WILL HAVE THE POTENTIAL TO PRODUCE STRONG WINDS AND
POTENTIALLY SEVERE HAIL.

..LEITMAN.. 08/14/2011

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

ATTN...WFO...BIS...UNR...BYZ...GGW...

LAT...LON   49170622 49130542 48920447 48290385 47550343 46330323
            45500336 45230348 45020385 44920455 44960568 45140597
            45410597 45960571 46670556 47530579 48290643 48920685
            49120662 49170622

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Aug 14, 11:46 AM MDTMesoscale DiscussionSPCDickey, Emmons, LaMoure, Logan, McIntosh59 min
Aug 14, 1:59 PM MDTMesoscale DiscussionSPCBennett, Custer, Fall River, Jackson, Lawrence, Meade and 2 more91 min

Nearby

Mesoscale Discussions in Montana, 2011Mesoscale Discussions in North Dakota, 2011Mesoscale Discussions in South Dakota, 2011Every mesoscale discussion in 2011

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.