Alert archive / Montana / Mesoscale Discussions in 2012
Mesoscale Discussion 284
The Storm Prediction Center issued this mesoscale discussion at Mar 19, 2012, 1:57 AM MDT for 14 counties in Montana. It was in force for 5 hr.
The area
The outline as issued.
The facts
- Issued
- Mar 19, 2012, 1:57 AM MDT (07:57 UTC)
- Expired
- Mar 19, 2012, 7:00 AM MDT
- In force
- 5 hr
- Issued by
- the Storm Prediction Center
Counties Blaine County, MT, Carbon County, MT, Chouteau County, MT, Fergus County, MT, Golden Valley County, MT, Hill County, MT, Judith Basin County, MT, Musselshell County, MT, Petroleum County, MT, Phillips County, MT, Stillwater County, MT, Sweet Grass County, MT, Wheatland County, MT, Yellowstone County, MT
The radar
The Billings radar (KBLX), 154 km from the middle of the area, began a volume at 08:00 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, 8.0 hours before the alert went out and 116 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
- 670 m above ground
- 0-6 km bulk shear
- 50 kt
- 0-1 km storm-relative helicity
- 193 m²/s²
- 0-3 km storm-relative helicity
- 466 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted, in the capitals the NWS used until 2016.
220
ACUS11 KWNS 190757
SWOMCD
SPC MCD 190757
MTZ000-191300-
MESOSCALE DISCUSSION 0284
NWS STORM PREDICTION CENTER NORMAN OK
0257 AM CDT MON MAR 19 2012
AREAS AFFECTED...CNTRL MT
CONCERNING...HEAVY SNOW
VALID 190757Z - 191300Z
SNOWFALL RATES FROM 1-2 IN/HR ARE FORECAST TO DEVELOP OVER CNTRL MT
BETWEEN 09-12Z. HEAVY SNOW WILL THEN SPREAD NWD INTO N-CNTRL MT BY
12-15Z...AND THEN DIMINISH IN INTENSITY TOWARD MID-DAY.
EARLY MORNING WV IMAGERY SHOWS AN UPPER-LEVEL DISTURBANCE LIFTING
NWD ACROSS WY. AS THIS FEATURE ENTERS MT TOWARD 12Z...SHORT TERM
MODEL GUIDANCE INDICATES RAPID LOW TO MIDLEVEL CYCLOGENESIS WILL
TAKE PLACE OVER THE ERN HALF OF THE STATE. THIS WILL LEAD TO THE
DEVELOPMENT OF A STRENGTHENING 700 MB DEFORMATION ZONE OVER CNTRL
MT...WHERE INCREASING FRONTOGENESIS COUPLED WITH LARGE-SCALE UVV/S
WILL FAVOR INTENSE ASCENT FAVORABLE FOR HEAVY SNOWFALL.
MEANWHILE...FREEZING LINE NEAR THE SURFACE WILL INITIALLY BE LOCATED
FROM 30 NNW OF HVR SWD TO LWT TO 45 NNW OF COD. HOWEVER...AS THE
LOW-LEVEL CYCLONE INTENSIFIES...AND STRONG ASCENT OVERSPREADS THE
REGION...SUB-FREEZING BOUNDARY LAYER TEMPERATURES ARE FORECAST TO
SPREAD/DEVELOP EWD TOWARD A LINE FROM 65 NW OF GGW SWD TO 15 N OF
SHR DURING THE 09Z TO 15Z TIME PERIOD. THUS...HEAVY SNOWFALL...WITH
RATES FROM 1-2 IN/HR...WILL BECOME INCREASINGLY PROBABLE DURING THE
MORNING...BEGINNING OVER S-CNTRL/CNTRL MT BY 09-12Z AND SPREADING
NWD INTO N-CNTRL MT BY 12-15Z.
IN ADDITION...N-NWLY WINDS OVER THE LOWEST 1 KM AGL ARE FORECAST TO
STRENGTHEN TO 35 KT DURING THE MORNING...WHICH MAY LEAD TO GUSTY
SURFACE CONDITIONS RESULTING IN BLOWING SNOW AND VISIBILITY REDUCED
TO A HALF MILE.
..GARNER.. 03/19/2012
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...BYZ...GGW...TFX...
LAT...LON 48960781 45600774 45110909 45831033 46951064 48971035
48960781Nearby
Mesoscale Discussions in Montana, 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.