Alert archive / Montana / Mesoscale Discussions in 2015

Mesoscale Discussion 1663

August 11, 20158 counties in Montana

The Storm Prediction Center issued this mesoscale discussion at Aug 11, 2015, 4:08 PM MDT for 8 counties in Montana. It was in force for 67 min.

The area

The outline as issued.

The facts

Issued
Aug 11, 2015, 4:08 PM MDT (22:08 UTC)
Expired
Aug 11, 2015, 5:15 PM MDT
In force
67 min
Issued by
the Storm Prediction Center
Chance of a watch
5%

Counties Deer Lodge County, MT, Granite County, MT, Lake County, MT, Mineral County, MT, Missoula County, MT, Powell County, MT, Ravalli County, MT, Silver Bow County, MT

The radar

The Missoula radar (KMSX), 49 km from the middle of the area, began a volume at 22:10 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

Spokane, WA (KOTX), launched 12:00Z, 10.1 hours before the alert went out and 218 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, Spokane, WA at 12:00Z on 2015-08-11Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 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, Spokane, WA at 12:00Z on 2015-08-11The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 15 square meters per square second.193958Sfc1 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
2189 m above ground
0-6 km bulk shear
39 kt
0-1 km storm-relative helicity
15 m²/s²
0-3 km storm-relative helicity
83 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

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

050 
ACUS11 KWNS 112209
SWOMCD
SPC MCD 112208 
MTZ000-IDZ000-112315-

MESOSCALE DISCUSSION 1663
NWS STORM PREDICTION CENTER NORMAN OK
0508 PM CDT TUE AUG 11 2015

AREAS AFFECTED...NRN ID / WRN MT

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY 

VALID 112208Z - 112315Z

PROBABILITY OF WATCH ISSUANCE...5 PERCENT

SUMMARY...ISOLATED STRONG TO SEVERE WIND GUSTS ARE POSSIBLE INTO THE
EARLY EVENING.  LOW SPATIAL COVERAGE/MAGNITUDE OF THREAT WILL
PRECLUDE A SEVERE THUNDERSTORM WATCH ISSUANCE.

DISCUSSION...SURFACE CONDITIONS OVER WRN MT HAVE WARMED TO NEAR 90
DEG F AND TEMP-DEWPOINT SPREADS ARE NOW IN THE 40-45 DEG RANGE. 
VERY STEEP MID-LEVEL LAPSE RATES SAMPLED BY THE 12Z BOI AND TFX
RAOBS ARE CONTRIBUTING TO WEAK BUOYANCY.  THE INVERTED-V PROFILES
/NEAR DRY ADIABATIC 0-3 KM LAPSE RATES/ WILL SUPPORT A FEW
MICROBURSTS WITH THE LARGER CORES AS THEY DEVELOP NWD INVOF THE
ID/MT BORDER.  THE STRONGER DOWNDRAFTS MAY OCCASIONALLY YIELD
POCKETS OF HIGHER GUSTS AND POTENTIALLY BE CAPABLE OF 50-65 MPH
WINDS.

..SMITH/THOMPSON.. 08/11/2015

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

ATTN...WFO...TFX...MSO...OTX...

LAT...LON   45491438 46051547 47431538 47801441 47801320 47061236
            45701256 45491438

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Aug 10, 7:12 PM MDTMesoscale DiscussionSPCFlathead, Lake, Lincoln, Mineral, Missoula, Powell and 1 more63 min

Nearby

Mesoscale Discussions in Montana, 2015Every mesoscale discussion in 2015

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.