Alert archive / Montana / Severe Thunderstorm Warnings in 1990

Severe Thunderstorm Warning 5, NWS Missoula, MT

August 20, 1990Flathead County, Montana

NWS Missoula, MT issued this severe thunderstorm warning at Aug 20, 1990, 5:42 PM MDT for Flathead County, Montana. It was in force for 63 min.

The area

The counties it named.

The facts

Issued
Aug 20, 1990, 5:42 PM MDT (23:42 UTC)
Expired
Aug 20, 1990, 6:45 PM MDT
In force
63 min
Issued by
NWS Missoula, MT
Area
Whole counties

County Flathead 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

Spokane, WA (KOTX), launched 12:00Z, 11.7 hours before the alert went out and 187 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 1990-08-20Temperature 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 1990-08-20The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 45 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
3609 m above ground
0-6 km bulk shear
20 kt
0-1 km storm-relative helicity
45 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 KGTF 202342
SVRFCA
MTC029-210045-
 
BULLETIN - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE KALISPELL MT
ISSUED BY GREAT FALLS MT
542 PM MDT MON AUG 20 1990
 
THE NATIONAL WEATHER SERVICE HAS ISSUED A
SEVERE THUNDERSTORM WARNING EFFECTIVE UNTIL  645 PM MDT
FOR PEOPLE IN THE FOLLOWING LOCATION......
 
IN NORTHWEST MONTANA
 
   ...FLATHEAD COUNTY
 
A WEATHER OBSERVER AT BIG FORK REPORTED A WIND GUST TO 65 MPH AND PEA
SIZED HAIL.
 
SEVERE THUNDERSTORMS PRODUCE DAMAGING WIND IN EXCESS OF 55
MPH...DESTRUCTIVE HAIL...DEADLY LIGHTNING...AND VERY HEAVY RAIN.
FOR YOUR PROTECTION MOVE TO AN INTERIOR ROOM ON THE LOWEST FLOOR
OF YOUR HOME OR BUSINESS.  HEAVY RAINS FLOOD tROADS QUICKLY SO
DON'T DRIVE INTO AREAS WHERE WATER COVERS THE ROAD.

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.

In the hours before

Special weather statement, Aug 20, 2:30 PM MDT, 3 hours 12 minutes before
MTZ001-002-200200-

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE MISSOULA MT
230 PM MDT MON AUG 20 1990

...STRONG THUNDERSTORMS MOVING THROUGH WESTERN MONTANA...

AT 220 PM MDT...NUMEROUS THUNDERSTORMS WERE DETECTED ON RADAR IN
PORTIONS OF RAVALLI.. MISSOULA.. AND GRANITE COUNTIES.  THESE
THUNDERSTORMS ARE STILL DEVELOPING AND ARE MOVING TO THE NORTH
AT ABOUT 20 MILES AN HOUR.

THESE THUNDERSTORMS MAY CONTAIN STRONG GUSTY WINDS..BRIEF HEAVHY RAIN..
FREQUENT LIGHTNING AND SMALL HAIL AND WILL CONTINUE THROUGH THIS AFTERNOON.

FURTHER STATEMENTS WILL BE ISSUED IF NECESSARY.

END/DWG
Special weather statement, Aug 20, 3:05 PM MDT, 2 hours 37 minutes before
MTZ001-210400-

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE KALISPELL MONTANA
305 PM MDT MON AUG 20 1990

...STRONG THUNDERSTORMS DEVELOPING IN SOUTHWESTERN MONTANA AND CENTRAL
IDAHO...

AT 300 PM MDT NUMEROUS THUNDERSTORMS WERE BEING PICKED UP BY RADAR OUT
OF MISSOULA. THESE THUNDERSTORMS ARE CURRENTLY IN RAVALLI...MISSOULA
AND GRANITE COUNTIES. THESE THUNDERSTORMS ARE MOVING TO THE NORTH AT
20 MPH.

THE THUNDERSTORMS WILL CONTINUE TO DEVELOPE AND MOVE TOWARDS THE NORTH
ACCOMPANIED BY STRONG GUSTY WINDS..BRIEF HEAVY RAIN..FREQUENT
LIGHTNING AND A RISK OF SMALL HAIL. THIS ACTIVITY WILL CONTINUE
THROUGH EARLY TONIGHT.

PERSONS OUTDOORS...PARTICULARLY BOATERS SHOULD SEEK REFUGE WHEN THESE
STORMS APPROACH. THE NATIONAL WEATHER SERVICE WILL CONTINUE TO MONITOR
THESE STORMS AND ISSUE ADDITIONAL STATEMENTS AS NECESSARY. IF DAMAGING
WEATHER OCCURS CONTACT YOUR NATIONAL WEATHER SERVICE OFFICE AT
755-4829.

/BILODEAU/

NNNN
Special weather statement, Aug 20, 4:41 PM MDT, 1 hour 1 minute before
MTZ001-002-210100-

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE MISSOULA MT
430 PM MDT MON AUG 20 1990

...STRONG THUNDERSTORMS MOVING THROUGH WESTERN MONTANA...

AT 420 PM MDT...NUMEROUS THUNDERSTORMS WERE DETECTED ON RADAR IN
PORTIONS OF MINERAL...SANDERS...LAKE AND NORTHERN MISSOULA COUNTIES
AND ARE MOVING TO THE NORTH AT ABOUT 25 MILES AN HOUR.

THESE THUNDERSTORMS MAY CONTAIN STRONG GUSTY WINDS..BRIEF HEAVY RAIN..
FREQUENT LIGHTNING A8ND SMALL HAIL AND WILL CONTINUE THROUGH THIS AFTERNOON.

FURTHER STATEMENTS WILL BE ISSUED IF NECESSARY.

END/RON
Special weather statement, Aug 20, 5:08 PM MDT, 34 minutes before
MTZ001-210400-

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE KALISPELL MONTANA
500 PM MDT MON AUG 20 1990

...STRONG THUNDERSTORMS MOVING INTO SOUTHERN FLATHEAD COUNTY...

AT 440 PM MDT STRONG THUNDERSTORMS WERE DETECTED ON MISSOULA RADAR IN
NORTHERN PORTIONS OF SANDERS AND LAKE COUNTIES. THESE STORMS WERE
MOVING TO THE NORTH AT 25 MPH AND WILL MOVE ACROSS FLATHEAD COUNTY
FOR THE NEXT FEW HOURS.

THESE THUNDERSTORMS MAY CONTAIN STRONG GUSTY WINDS...BRIEF HEAVY
RAIN...FREQUENT LIGHTNING AND SMALL HAIL.

PERSONS OUTDOORS...PARTICULARLY BOATERS SHOULD SEEK REFUGE WHEN THESE
STORMS APPROACH. THE NATIONAL WEATHER SERVICE WILL CONTINUE TO
MONITOR THESE STRONG STORMS AND ISSUE OTHER STATEMRENTS AS NECESSARY.

END/TJC

The office that day

Everything else NWS Missoula, MT issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Aug 19, 7:55 PM MDTFlash Flood WarningMSOLewis and Clark2 hr

Nearby

Severe Thunderstorm Warnings in Montana, 1990Every severe thunderstorm warning in 1990

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.