Alert archive / Montana / Severe Thunderstorm Warnings in 1989

Severe Thunderstorm Warning 13, NWS Missoula, MT

July 23, 1989Lewis and Clark County, Montana

NWS Missoula, MT issued this severe thunderstorm warning at Jul 23, 1989, 5:00 PM MDT for Lewis and Clark County, Montana. It was in force for 30 min.

The area

The counties it named.

The facts

Issued
Jul 23, 1989, 5:00 PM MDT (23:00 UTC)
Expired
Jul 23, 1989, 5:30 PM MDT
In force
30 min
Issued by
NWS Missoula, MT
Area
Whole counties

County Lewis and Clark County, MT

The radar

The WSR-88D network and its archive begin in 1991, so there is no radar volume for this alert.

The nearest sounding before it

Great Falls, MT (KGTF), launched 12:00Z, 11.0 hours before the alert went out and 91 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 1989-07-23Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 238 joules per kilogram.LCLLFCEL10008507005003002001001 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 1989-07-23The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 27 square meters per square second.19395878Sfc1 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
238 J/kg
Mixed-layer CIN
-317 J/kg
Mixed-layer LCL
1802 m above ground
0-6 km bulk shear
14 kt
0-1 km storm-relative helicity
27 m²/s²
0-3 km storm-relative helicity
76 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 KHLN 232300
SVRHLN
MTC049-240000-

BULLETIN - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WARNING 
NATIONAL WEATHER SERVICE HELENA MT
500 PM MDT SUN JUL 23 1989

THE NATIONAL WEATHER SERVICE HAS ISSUED A SEVERE THUNDERSTORM 
WARNING EFFECTIVE UNTIL 600 PM MDT FOR PEOPLE IN THE FOLLOWING 
COUNTY

   IN THE SOUTHWEST PART OF MONTANA
      LEWIS AND CLARK

AT 4 55 PM MDT A SEVERE THUNDERSTORM WAS OCCURING AT THE HELENA
AIRPORT.  THE NATIONAL WEATHER SERVICE OFFICE WAS REPORTING WINDS
IN EXCESS OF 60 MILES AN HOUR.  HEAVY RAIN...SMALL HAIL AND
FREQUENT AND DANGEROUS LIGHTNING STRIKES WERE ALSO OCCURING WITH
THIS THUNDERSTORM.  THE THUNDERSTORM WAS MOVING EAST NORTHEAST
AT 20 MILES AN HOUR.

THUNDERSTORMS KILL MORE PEOPLE EACH YEAR THAT ANY OTHER TYPE STORM.
WHEN THUNDERSTORMS ARE OCCURRING...PEOPLE SHOULD MOVE INSIDE A
BUILDING AND NOT STAND NEAR WINDOWS.   DO NOT USE TELEPHONES OR
ELECTRICAL APPLIANCES UNTIL THE STORM HAS PASSED.

Nearby

Severe Thunderstorm Warnings in Montana, 1989Every severe thunderstorm warning in 1989

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.