Alert archive / Montana / Severe Thunderstorm Warnings in 1997

Severe Thunderstorm Warning 56, NWS Missoula, MT

August 20, 1997Missoula County, Montana

NWS Missoula, MT issued this severe thunderstorm warning at Aug 20, 1997, 7:23 PM MDT for Missoula County, Montana. It was in force for 67 min. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued: Aug 20, 1997, 7:23 PM MDT (01:23 UTC)
Expired: Aug 20, 1997, 8:30 PM MDT
In force: 67 min
Issued by: NWS Missoula, MT
Area: Whole counties

County Missoula County, MT

The nearest sounding before it

Spokane, WA (KOTX), launched 00:00Z, 1.4 hours before the alert went out and 201 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: 255 J/kg
Mixed-layer CIN: -161 J/kg
Mixed-layer LCL: 2579 m above ground
0-6 km bulk shear: 33 kt
0-1 km storm-relative helicity: 21 m²/s²
0-3 km storm-relative helicity: 51 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 
TTAA00 KMSO 210124 RRA
SVRMSO
MTC063-210230-
 
BULLETIN - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE MISSOULA MT
723 PM MDT WED AUG 20 1997
 
THE NATIONAL WEATHER SERVICE IN MISSOULA HAS ISSUED A
SEVERE THUNDERSTORM WARNING EFFECTIVE UNTIL  830 PM MDT
FOR PEOPLE IN THE FOLLOWING LOCATION...
 
IN WEST CENTRAL MONTANA
 
   ...MISSOULA COUNTY
 
AT 720 PM MDT WEATHER RADAR INDICATED A LINE OF SEVERE THUNDERSTORMS
MOVING INTO THE SOUTHWEST CORNER OF MISSOULA COUNTY. THIS LINE WAS
MOVING TO THE NORTHEAST AT 20 MPH. THESE STORMS MAY PRODUCE VERY STRONG
WINDS GREATER THAN 60 MPH AND HAIL. THIS LINE WILL MOVE INTO THE LOLO
AREA AROUND 745 PM AND MISSOULA BY 8 PM.
 
WHEN THUNDERSTORMS ARE OCCURRING...PEOPLE SHOULD MOVE INSIDE A
STRONG BUILDING.  DO NOT STAND BY WINDOWS.  DON'T USE TELEPHONES
OR ELECTRICAL APPLIANCES UNLESS IN AN EMERGENCY UNTIL THE STORM
HAS PASSED.  MOTORISTS SHOULD NOT DRIVE INTO LOW WATER CROSSINGS.

What forecasters said that day

The local office's own words before this severe thunderstorm warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Missoula, MT wrote its last area forecast discussion before this severe thunderstorm warning went out at Aug 20, 1:55 PM MDT, 5 hours 28 minutes earlier.

Area forecast discussion, Aug 20, 1:55 PM MDT, 5 hours 28 minutes before

WESTERN MONTANA AND NORTH CENTRAL IDAHO FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
155 PM MDT WED AUG 20 1997

NGM ALREADY LOOKS BETTER THAN ETA OVER FASTER PROGRESSION OF LOW
LEVEL MOISTURE AND SHORTWAVE IN OREGON...BUT EVEN IT IS TOO SLOW.
CONVECTIVE CLOUDS ARE BEGINNING IN CENTRAL ID MOUNTAINS WHERE SUN
HAS BEEN STRONG FOR AWHILE THOUGH NOTHING ON RADAR YET. VORT LOBE
EXTENDING SOUTHEAST FROM LOW CENTER TOWARD SOUTHEAST OREGON CORNER
IS MOVING NORTHEAST AND EXTRAPOLATION PLACES THE VORT AXIS NEAR MSO
BY 00Z. NOT SURE ABOUT MUCH CONVECTION AFTER IT PASSES SO AM NOT KEEN
ON HIGH POPS ANYWHERE TONIGHT EXCEPT NORTHWEST MT. DRY SOUTHWEST FLOW
EXPECTED AFTER FIRST PERIOD AND WILL STICK WITH THE NIL MOS POPS. MID
AND HIGH LEVEL CIRCULATION ASSOCIATED WITH THE EXTRATROPICAL LOW IS
PERSISTENTLY STRONG AND WILL CONCEDE LIMITED COOL ADVECTION FROM IT
FOR THU. WARMING UP AFTERWARD IN SOUTHWEST FLOW ON FRI BUT 93 FOR MSO
LOOKS OVERDONE...AND 90 AT P69 UNDERDONE. GV

...FORECASTS BELOW ARE PRELIMINARY AND SUBJECT TO CHANGE...

LIB .. 056/082 046/090 ... 356100
FCA UU 056/080 045/087 047 356000
POL .. 060/083 051/088 ... 356000
MSO UU 056/084 049/090 051 354000
HMM .. 057/086 048/092 ... 354000
BTM .. 046/083 042/087 ... 354000
S80 .. 054/084 050/088 ... 352000
P69 .. 059/088 054/093 ... 352000
SMN .. 057/085 051/090 ... 352000

Nearby

Severe Thunderstorm Warnings in Montana, 1997 Every severe thunderstorm warning in 1997

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.