Alert archive / Montana / Mesoscale Discussions in 2012
Mesoscale Discussion 1752
The Storm Prediction Center issued this mesoscale discussion at Aug 13, 2012, 11:53 AM MDT for 15 counties in Montana. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- Aug 13, 2012, 11:53 AM MDT (17:53 UTC)
- Expired
- Aug 13, 2012, 2:00 PM MDT
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
- Chance of a watch
- 20%
Counties Carter County, MT, Custer County, MT, Dawson County, MT, Fallon County, MT, Garfield County, MT, McCone County, MT, Petroleum County, MT, Phillips County, MT, Powder River County, MT, Prairie County, MT, Richland County, MT, Rosebud County, MT, Treasure County, MT, Valley County, MT, Wibaux County, MT
The radar
The Glasgow radar (KGGW), 101 km from the middle of the area, began a volume at 17:54 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, 5.9 hours before the alert went out and 102 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
- 2281 m above ground
- 0-6 km bulk shear
- 48 kt
- 0-1 km storm-relative helicity
- 172 m²/s²
- 0-3 km storm-relative helicity
- 276 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.2
The text
As transmitted, in the capitals the NWS used until 2016.
239
ACUS11 KWNS 131753
SWOMCD
SPC MCD 131753
MTZ000-WYZ000-132000-
MESOSCALE DISCUSSION 1752
NWS STORM PREDICTION CENTER NORMAN OK
1253 PM CDT MON AUG 13 2012
AREAS AFFECTED...ERN MT
CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY
VALID 131753Z - 132000Z
PROBABILITY OF WATCH ISSUANCE...20 PERCENT
SUMMARY...ISOLATED SEVERE THREAT WILL CONTINUE INTO THE AFTERNOON.
MARGINALLY SEVERE HAIL AND STRONG/LOCALLY DAMAGING WIND GUSTS ARE
POSSIBLE WITH STRONGER STORMS. SEVERE THREAT IS EXPECTED TO REMAIN
SUFFICIENTLY ISOLATED TO NOT WARRANT A WW...BUT TRENDS WILL CONTINUE
TO BE MONITORED.
DISCUSSION...ELEVATED CONVECTION IS EXPECTED TO CONTINUE INTO THE
AFTERNOON ACROSS PORTIONS OF NERN MT WITH ADDITIONAL DEVELOPMENT
EXPECTED ACROSS SE MT LATER TODAY. CURRENT STORMS W/SW OF GGW WERE
TRACKING SEWD IN VICINITY OF SFC WARM FRONT EXTENDING S/SE INTO WRN
SD AND ARE LIKELY DUE TO WAA OVER THE FRONT...LEADING TO ELEVATED
CONVECTION IN LOW CAPE/HIGH SHEAR ENVIRONMENT. AS AIRMASS CONTINUES
TO DESTABILIZE AHEAD OF THESE STORMS...SOME ORGANIZATION IS POSSIBLE
GIVEN BULK SHEAR VALUES AROUND 40-50 KT. STEEP LAPSE RATES AND COOL
TEMPERATURES ALOFT MAY SUPPORT SPORADIC...MARGINALLY SEVERE
HAIL...THOUGH INSTABILITY WILL CONTINUE TO BE A LIMITING FACTOR FOR
MORE ROBUST STORM UPDRAFTS. WITH MEAGER SFC MOISTURE TO WORK WITH
AND DRY SUB-CLOUD LAYERS INDICATED BY FORECAST SOUNDINGS/MODIFIED
12Z GGW RAOB...STRONG/LOCALLY DAMAGING WIND GUSTS WILL ALSO BE
POSSIBLE. CONVECTIVE TRENDS WILL BE MONITORED BUT A WW IS NOT
CURRENTLY ANTICIPATED DUE TO EXPECTED ISOLATED NATURE OF SEVERE
THREAT.
..LEITMAN/CARBIN.. 08/13/2012
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...UNR...BYZ...GGW...TFX...
LAT...LON 48990707 47540405 45030407 44980602 45700705 47370852
48210864 48910804 48990707SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 13, 4:10 PM MDT | Mesoscale Discussion | SPC | Big Horn, Carter, Custer, Fallon, Powder River, Prairie and 2 more | 2 hr |
Nearby
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.