Alert archive / Montana / Mesoscale Discussions in 2004

Mesoscale Discussion 2154

September 1, 20046 counties in Idaho; 23 counties in Montana; Wallowa County, Oregon

The Storm Prediction Center issued this mesoscale discussion at Sep 1, 2004, 1:28 PM MDT for 6 counties in Idaho; 23 counties in Montana; Wallowa County, Oregon. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: Sep 1, 2004, 1:28 PM MDT (19:28 UTC)
Expired: Sep 1, 2004, 3:30 PM MDT
In force: 2 hr
Issued by: the Storm Prediction Center

All 30 counties

Adams County, ID, Clearwater County, ID, Idaho County, ID, Lewis County, ID, Shoshone County, ID, Valley County, ID, Broadwater County, MT, Cascade County, MT, Chouteau County, MT, Deer Lodge County, MT, Flathead County, MT, Glacier County, MT, Granite County, MT, Hill County, MT, Jefferson County, MT, Judith Basin County, MT, Lake County, MT, Lewis and Clark County, MT, Liberty County, MT, Meagher County, MT, Mineral County, MT, Missoula County, MT, Pondera County, MT, Powell County, MT, Ravalli County, MT, Sanders County, MT, Silver Bow County, MT, Teton County, MT, Toole County, MT, Wallowa County, OR

The radar

The Missoula radar (KMSX), 47 km from the middle of the area, began a volume at 19:29 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, 7.5 hours before the alert went out and 232 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 170 J/kg
Mixed-layer CIN: -203 J/kg
Mixed-layer LCL: 2259 m above ground
0-6 km bulk shear: 42 kt
0-1 km storm-relative helicity: 91 m²/s²
0-3 km storm-relative helicity: 120 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.

634 
ACUS11 KWNS 011931
SWOMCD
SPC MCD 011928 
MTZ000-IDZ000-ORZ000-WAZ000-012130-

MESOSCALE DISCUSSION 2154
NWS STORM PREDICTION CENTER NORMAN OK
0228 PM CDT WED SEP 01 2004

AREAS AFFECTED...FAR NERN ORE NEWD INTO NRN ID AND WRN MT

CONCERNING...SEVERE THUNDERSTORM POTENTIAL...OUTLOOK UPGRADE 

VALID 011928Z - 012130Z

THUNDERSTORM COVERAGE WILL INCREASE OVER THE MTNS OF FAR NERN
ORE...NRN ID INTO WRN MT OVER THE NEXT FEW HOURS WITH ACTIVITY
BEGINNING TO MOVE INTO THE LOWER ELEVATIONS OF CENTRAL MT BY MID
AFTERNOON. SOME OF THE STRONGEST STORMS WILL BE CAPABLE OF PRODUCING
DAMAGING WINDS/LARGE HAIL. AREA WILL BE UPGRADED TO SLIGHT RISK IN
20Z DAY 1 OUTLOOK.

LATEST VISIBLE SAT IMAGERY INDICATES CONVECTION WAS DEVELOPING OVER
THE HIGHER TERRAIN OF NERN ORE...NRN ID AND WRN MT WHERE LOW LEVEL
UPSLOPE FLOW/CONVERGENCE WAS BEING MAXIMIZED ALONG FRONTAL BOUNDARY
AND REGION OF STRONGEST MID LEVEL FRONTOGENETIC FORCING. A NARROW
ZONE OF LOWER 50S DEWPTS STILL REMAIN OVER MUCH OF THE REGION...AND
COMBINED WITH CONTINUED DAYTIME HEATING SHOULD AID IN MLCAPES AROUND
1000 J/KG. 40-50 KT CLOUD BEARING SHEAR ALONG WITH STEEP MID LEVEL
LAPSE RATES WILL SUPPORT LARGE HAIL AS THE PRIMARY THREAT OVER THE
MTNS/HIGHER TERRAIN. AS CONVECTION MOVES EWD INTO THE LOWER
ELEVATIONS OF WRN AND CENTRAL MT...DEWPT DEPRESSIONS ARE 40-50 DEG
F. COMBINED WITH LINEAR FORCING ALONG FRONTAL BOUNDARY THIS WILL AID
IN AN INCREASING TREND TOWARDS DAMAGING WINDS AS THE PRIMARY THREAT
OVER THIS AREA.

..CROSBIE.. 09/01/2004

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

ATTN...WFO...BYZ...TFX...MSO...BOI...OTX...PDT...

44741718 45331770 46491658 47511576 48591465 49111277
48810987 47850929 47020945 46251019 45151281 44821531

Nearby

Mesoscale Discussions in Montana, 2004 Mesoscale Discussions in Idaho, 2004 Mesoscale Discussions in Oregon, 2004 Every mesoscale discussion in 2004

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.