Alert archive / Montana / Mesoscale Discussions in 2016
Mesoscale Discussion 671
The Storm Prediction Center issued this mesoscale discussion at May 21, 2016, 6:38 PM MDT for 16 counties in Montana; Campbell County, Wyoming. It was in force for 67 min.
The area
The outline as issued.
The facts
- Issued
- May 21, 2016, 6:38 PM MDT (00:38 UTC)
- Expired
- May 21, 2016, 7:45 PM MDT
- In force
- 67 min
- Issued by
- the Storm Prediction Center
Counties Carter County, MT, Custer County, MT, Daniels County, MT, Dawson County, MT, Fallon County, MT, Garfield County, MT, McCone County, MT, Phillips County, MT, Powder River County, MT, Prairie County, MT, Richland County, MT, Roosevelt County, MT, Rosebud County, MT, Sheridan County, MT, Valley County, MT, Wibaux County, MT, Campbell County, WY
The radar
The Glasgow radar (KGGW), 177 km from the middle of the area, began a volume at 00:39 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 00:00Z, 0.6 hours before the alert went out and 178 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
- 1500 J/kg
- Mixed-layer CIN
- -10 J/kg
- Mixed-layer LCL
- 1883 m above ground
- 0-6 km bulk shear
- 34 kt
- 0-1 km storm-relative helicity
- 57 m²/s²
- 0-3 km storm-relative helicity
- 70 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 3.5
The text
As transmitted.
622
ACUS11 KWNS 220038
SWOMCD
SPC MCD 220038
MTZ000-WYZ000-220145-
MESOSCALE DISCUSSION 0671
NWS STORM PREDICTION CENTER NORMAN OK
0738 PM CDT SAT MAY 21 2016
AREAS AFFECTED...ERN MT....NERN WY
CONCERNING...SEVERE THUNDERSTORM WATCH 188...189...
VALID 220038Z - 220145Z
THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH
188...189...CONTINUES.
SUMMARY...THE THREAT FOR DMGG WINDS AND ISOLATED INSTANCES OF LARGE
HAIL CONTINUES ACROSS SVR TSTM WATCHES 188 AND 189.
DISCUSSION...A BROKEN LINE OF TSTMS HAS EVOLVED ALONG OUTFLOW
BOUNDARY/COLD FRONT ACROSS ERN MT INTO NERN WY. DMGG WINDS HAVE
LIKELY BECOME THE DOMINANT THREAT ACROSS THESE AREAS...MAXIMIZED
NEAR/W OF KGGW WHERE THE NWRN SEGMENT OF CONVECTION IS ORIENTED
PERPENDICULAR TO THE DEEP-LAYER FLOW. RECENT RADAR TRENDS ALSO
SUPPORT THE POTENTIAL FOR VERY STRONG WINDS ACROSS THIS AREA. LARGE
HAIL ALSO REMAINS POSSIBLE WITHIN STRONGER CONVECTIVE
CORES...INCLUDING THE LONGER-LIVED SUPERCELL CLUSTER APPROACHING
KGGW...BUT THIS THREAT HAS BECOME MORE LOCALIZED DUE TO THE
CONVECTIVE MODE EVOLUTION. THE 00Z GGW RAOB SAMPLED AN UNSTABLE AIR
MASS CHARACTERIZED BY STEEP LOW-MIDLEVEL LAPSE RATES AND MODERATELY
STRONG NEARLY UNIDIRECTIONAL DEEP-LAYER FLOW...FAVORABLE FOR
MAINTAINING A SVR THREAT THROUGH 03Z...DESPITE THE IMMINENT LOSS OF
DIURNAL HEATING.
..ROGERS.. 05/22/2016
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...UNR...BYZ...GGW...RIW...TFX...
LAT...LON 49130441 45900404 43570519 43500594 43900657 45530675
47120699 47900793 48270838 48980857 49130441SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 21, 8:16 PM MDT | Mesoscale Discussion | SPC | Carter, Powder River | 89 min |
Nearby
Mesoscale Discussions in Montana, 2016Mesoscale Discussions in Wyoming, 2016Every mesoscale discussion in 2016
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.