Alert archive / Montana / Flash Flood Warnings in 1990

Flash Flood Warning 2, NWS Missoula, MT

August 19, 1990Lewis and Clark County, Montana

NWS Missoula, MT issued this flash flood warning at Aug 19, 1990, 7:55 PM MDT for Lewis and Clark County, Montana. It was in force for 2 hr.

The area

The counties it named.

The facts

Issued
Aug 19, 1990, 7:55 PM MDT (01:55 UTC)
Expired
Aug 19, 1990, 10:00 PM MDT
In force
2 hr
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 00:00Z, 1.9 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 00:00Z on 1990-08-20Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 592 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 00:00Z on 1990-08-20The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 142 square meters per square second.193958Sfc1 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
592 J/kg
Mixed-layer CIN
-5 J/kg
Mixed-layer LCL
937 m above ground
0-6 km bulk shear
40 kt
0-1 km storm-relative helicity
142 m²/s²
0-3 km storm-relative helicity
203 m²/s²
Significant tornado parameter
0.6
Supercell composite
4.8

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

000 
TTAA00 KGTF 200159
FFWGTF
MTC049-200400-
 
BULLETIN - EBS ACTIVATION REQUESTED
FLASH FLOOD WATCH
NATIONAL WEATHER SERVICE GREAT FALLS MT
755 PM MDT SUN AUG 19 1990
 
THE NATIONAL WEATHER SERVICE IN GREAT FALLS HAS ISSUED A
FLASH FLOOD WATCH EFFECTIVE UNTIL 1000 PM MDT
FOR PEOPLE IN THE FOLLOWING LOCATION......
 
IN WEST CENTRAL MONTANA
 
   ...CENTRAL AND SOUTHERN LEWIS AND CLARK COUNTY...INCLUDING THE CITY
OF HELENA...
 
AT 745 PM MDT RADAR AND SATELLITE PICTURES INDICATED STRONG
THUNDERSTORMS IN CENTRAL AND SOUTHERN LEWIS AND CLARK COUNTIES. THESE
STORMS LIKELY CONTAIN HEAVY RAIN...WHICH COULD CAUSE LOCAL FLASH
FLOODING IN AND NEAR THE MOUNTAINS.
 
AT 745 PM CANYON FERRY ROAD WAS REPORTED AS FLOODED.
 
BE ESPECIALLY CAUTIOUS AT NIGHT WHEN IT IS HARDER TO RECOGNIZE
THE DANGERS OF FLOODS AND FLASH FLOODS.  IF FLASH FLOODING IS
OBSERVED...ACT QUICKLY.  MOVE UP TO ESCAPE FLOOD WATERS.  DO
NOT STAY IN AREAS SUBJECT TO FLOODING WHEN WATER BEGINS RISING.
 
A FLASH FLOOD WATCH MEANS THAT FLOODING IS POSSIBLE.
 
MOST FLASH FLOOD DEATHS OCCUR IN AUTOMOBILES.  DO NOT
ATTEMPT TO CROSS BRIDGES...DIPS...OR LOW SPOTS IF WATER COVERS
THE ROADWAY.  NEVER TRY TO CROSS A FLOWING STREAM...EVEN A SMALL
ONE...ON FOOT.  TO ESCAPE RISING WATER MOVE UP TO HIGHER GROUND.

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 20, 5:42 PM MDTSevere Thunderstorm WarningMSOFlathead63 min

Nearby

Flash Flood Warnings in Montana, 1990Every flash flood 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.