Alert archive / Montana / Mesoscale Discussions in 2003

Mesoscale Discussion 2145

August 11, 200315 counties in Montana; Park County, Wyoming

The Storm Prediction Center issued this mesoscale discussion at Aug 11, 2003, 2:23 PM MDT for 15 counties in Montana; Park County, Wyoming. It was in force for 97 min.

The area

The outline as issued.

The facts

Issued
Aug 11, 2003, 2:23 PM MDT (20:23 UTC)
Expired
Aug 11, 2003, 4:00 PM MDT
In force
97 min
Issued by
the Storm Prediction Center

Counties Beaverhead County, MT, Broadwater County, MT, Carbon County, MT, Deer Lodge County, MT, Gallatin County, MT, Granite County, MT, Jefferson County, MT, Lewis and Clark County, MT, Madison County, MT, Meagher County, MT, Park County, MT, Powell County, MT, Silver Bow County, MT, Stillwater County, MT, Sweet Grass County, MT, Park County, WY

The nearest sounding before it

Great_falls, MT (KTFX), launched 12:00Z, 8.4 hours before the alert went out and 199 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, Great_falls, MT at 12:00Z on 2003-08-11Temperature 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, Great_falls, MT at 12:00Z on 2003-08-11The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -57 square meters per square second.1939587897Sfc1 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
4296 m above ground
0-6 km bulk shear
42 kt
0-1 km storm-relative helicity
-57 m²/s²
0-3 km storm-relative helicity
121 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.

000 
ACUS11 KWNS 112024
SWOMCD
SPC MCD 112023 
MTZ000-WYZ000-IDZ000-112200-

MESOSCALE DISCUSSION 2145
NWS STORM PREDICTION CENTER NORMAN OK
0323 PM CDT MON AUG 11 2003

AREAS AFFECTED...ERN ID...SWRN MT...NWRN WY

CONCERNING...SEVERE THUNDERSTORM POTENTIAL...DRY LIGHTNING 

VALID 112023Z - 112200Z

THUNDERSTORMS WILL CONTINUE TO DEVELOP ACROSS THE HIGHER TERRAIN OF
ERN ID...SWRN MT AND NWRN WY THIS AFTERNOON...WITH THE THREAT FOR
ISOLATED STRONG WIND GUSTS WITHIN AND NE OF THE HIGHER TERRAIN. 
INCREASING DRY LIGHTNING COVERAGE WILL BE A THREAT FOR FIRE WEATHER
CONCERNS FROM PORTIONS OF ERN ID INTO SWRN MT.

VIS IMAGERY/LIGHTNING DATA SHOW STORMS HAVE DEVELOPED OVER THE
HIGHER TERRAIN OF ERN ID/SWRN MT AND NWRN WY WHERE SBCAPE IS AROUND
2000 J/KG.  40 KT OF SWLY MID-LEVEL FLOW ACROSS THIS REGION WITH A
WEAK SHORT WAVE TROUGH MOVING ACROSS ID TO SWRN MT BETWEEN 00-06Z
WILL CONTINUE TO SUPPORT UPDRAFTS FOR ADDITIONAL CONVECTIVE
DEVELOPMENT THROUGH THE AFTERNOON AND EVENING. LARGE SURFACE
DEWPOINT DEPRESSIONS ACROSS THE AREA OF CONCERN WILL FAVOR ISOLATED
DAMAGING WIND GUSTS WITH THE STRONGEST STORMS.

DRY LIGHTNING POTENTIAL WILL BE INCREASING DURING THE NEXT SEVERAL
HOURS FROM ERN ID INTO SWRN MT AS STORMS CONTINUE TO DEVELOP OVER
THIS REGION AND WITHIN AN AIR MASS WHERE SURFACE RELATIVE HUMIDITY
VALUES ARE AOB 20 PERCENT AND PRECIPITABLE WATER VALUES PER 12Z
SOUNDINGS ARE AOB 0.5 INCHES.

..PETERS.. 08/11/2003

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

ATTN...WFO...BYZ...RIW...TFX...PIH...MSO...

46541383 47431275 47121060 44630810 44091004 44711344

Nearby

Mesoscale Discussions in Montana, 2003Mesoscale Discussions in Wyoming, 2003Every mesoscale discussion in 2003

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.