Alert archive / Montana / Mesoscale Discussions in 2012
Mesoscale Discussion 2133
The Storm Prediction Center issued this mesoscale discussion at Dec 8, 2012, 8:24 AM MST for 10 counties in Montana; 8 counties in North Dakota. It was in force for 4 hr.
The area
The outline as issued.
The facts
- Issued
- Dec 8, 2012, 8:24 AM MST (15:24 UTC)
- Expired
- Dec 8, 2012, 12:30 PM MST
- In force
- 4 hr
- Issued by
- the Storm Prediction Center
Counties Custer County, MT, Dawson County, MT, Fallon County, MT, Garfield County, MT, McCone County, MT, Prairie County, MT, Richland County, MT, Rosebud County, MT, Treasure County, MT, Wibaux County, MT, Billings County, ND, Dunn County, ND, Golden Valley County, ND, Hettinger County, ND, McKenzie County, ND, Mercer County, ND, Slope County, ND, Stark County, ND
The radar
The Glasgow radar (KGGW), 196 km from the middle of the area, began a volume at 15:24 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, 3.4 hours before the alert went out and 196 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.
- Mixed-layer CAPE
- 0 J/kg
- Mixed-layer CIN
- No buoyant parcel
- Mixed-layer LCL
- 489 m above ground
- 0-6 km bulk shear
- 38 kt
- 0-1 km storm-relative helicity
- 21 m²/s²
- 0-3 km storm-relative helicity
- 146 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted, in the capitals the NWS used until 2016.
104
ACUS11 KWNS 081525
SWOMCD
SPC MCD 081524
NDZ000-MTZ000-081930-
MESOSCALE DISCUSSION 2133
NWS STORM PREDICTION CENTER NORMAN OK
0924 AM CST SAT DEC 08 2012
AREAS AFFECTED...ERN MT AND WRN ND
CONCERNING...HEAVY SNOW
VALID 081524Z - 081930Z
SUMMARY...A TRANSIENT THREAT OF HEAVY SNOW IS EXPECTED THIS MORNING
AND AFTERNOON AS A SNOW BAND PIVOTS ESEWD THROUGH ERN MT AND WRN ND.
INCH AN HOUR RATES WILL BE POSSIBLE...THOUGH THE DURATION OF HEAVY
SNOW MAY BE LIMITED DUE TO MIGRATORY NATURE OF THE ONGOING BAND.
DISCUSSION...THE APPROACH OF A COMPACT SHORT WAVE TROUGH /NOTED ON
WV IMAGERY OVER CNTRL MT AS OF 15Z/ IS INFLUENCING 850-700 MB
FRONTOGENESIS. AS SUCH...INCREASING UPWARD MOTION OWING TO FAVORABLE
JUXTAPOSITION OF LOW-LEVEL CONVERGENCE AND UPPER-LEVEL DIVERGENCE
WILL LIKELY MAINTAIN AN ONGOING SNOW BAND ACROSS NERN MT. LOW-LEVEL
SATURATION EVIDENCED ON THE 12Z GGW SOUNDING WILL SUPPORT INCH AN
HOUR RATES FOR AREAS BENEATH THE BAND. AS THE UPPER TROUGH
PROGRESSES SEWD WITH A SUBSEQUENT LOW-LEVEL MASS RESPONSE /DEEPENING
SURFACE PRESSURE/...THE BAND IS EXPECTED TO PIVOT SSEWD THROUGH THE
AFTERNOON...BECOMING FOCUSED EAST OF THE MCD AREA THEREAFTER. AS
THIS OCCURS...COLDER/DRIER AIR ADVECTING INTO THE REGION WILL LEAD
TO A CESSATION OF HEAVIER RATES FOR THE MCD AREA LATE THIS AFTERNOON
INTO THE EVENING.
..DISPIGNA.. 12/08/2012
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...BIS...BYZ...GGW...
LAT...LON 47470758 48120589 48200321 47710193 47450164 46850202
46430239 45950427 45610556 45560692 45730760 46590769
47470758SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Dec 8, 12:43 PM MST | Mesoscale Discussion | SPC | McIntosh | 4 hr |
| Dec 8, 4:58 PM MST | Mesoscale Discussion | SPC | Ransom, Richland, Sargent | 4 hr |
Nearby
Mesoscale Discussions in Montana, 2012Mesoscale Discussions in North Dakota, 2012Every mesoscale discussion in 2012
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.