Severe Thunderstorm Warning 21, NWS Great Falls, MT

Issued

Jun 21, 1999, 4:56 PM MDT (22:56 UTC)

Expired

Jun 21, 1999, 6:00 PM MDT

In force

64 min

Issued by

NWS Great Falls, MT

Area

Whole counties; the outline is the Mesonet’s reconstruction

Counties Fergus County, MT, Judith Basin County, MT

NCEI Storm Data entries that began inside the alert's area while it was in force. Before 2003 the local storm report archive is thin, so this is the record of what happened rather than what was phoned in.

567 
WUUS1 KGTF 212302 RRA
SVRGTF
MTC027-045-220000-

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE GREAT FALLS MT
456 PM MDT MON JUN 21 1999

THE NATIONAL WEATHER SERVICE IN GREAT FALLS HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  SOUTHWESTERN FERGUS COUNTY IN MONTANA
  THIS INCLUDES THE CITY OF LEWISTOWN
  NORTHEASTERN JUDITH BASIN COUNTY IN MONTANA

* UNTIL 600 PM MDT

* AT 453 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  SEVERE THUNDERSTORM ALONG A LINE EXTENDING FROM 10 MILES SOUTHWEST
  OF DENTON TO 10 MILES NORTHWEST OF HOBSON TO 7 MILES SOUTHWEST OF
  MOORE...OR ALONG A LINE EXTENDING FROM 8 MILES NORTHEAST OF
  STANFORD TO 11 MILES EAST OF STANFORD TO 21 MILES SOUTHWEST OF
  LEWISTOWN...MOVING EAST AT 20 MPH.

SEVERE THUNDERSTORMS CAN PRODUCE TORNADOES WITH LITTLE OR NO ADVANCE 
WARNING. PREPARE TO MOVE TO A PLACE OF SAFETY IN A STURDY STRUCTURE 
SUCH AS A BASEMENT OR SMALL INTERIOR ROOM IF A TORNADO IS SPOTTED.

THIS IS A DANGEROUS STORM. IF YOU ARE IN ITS PATH YOU SHOULD PREPARE
FOR DAMAGING WINDS IN EXCESS OF 55 MPH...LARGE HAIL...AND DEADLY
LIGHTNING. PEOPLE OUTSIDE SHOULD MOVE TO A SHELTER...PREFERABLY
INSIDE A STRONG BUILDING BUT AWAY FROM WINDOWS.

REPORT SEVERE WEATHER TO THE NEAREST LAW ENFORCEMENT AGENCY. THEY
WILL RELAY YOUR REPORT TO THE NATIONAL WEATHER SERVICE FORECAST
OFFICE IN GREAT FALLS.

A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT UNTIL 900 PM MDT MONDAY
EVENING FOR MONTANA.


LAT...LON 4731 11033 4711 11009 4679 10982 4696 10904           4727 
10930 4747 10954

NWS Great Falls, MT wrote its last area forecast discussion before this severe thunderstorm warning went out at Jun 21, 3:00 PM MDT, 1 hour 56 minutes earlier.

SOUTHWEST AND NORTH CENTRAL MONTANA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
300 PM MDT MON JUN 21 1999

MODELS IN AGREEMENT IN FORECASTING UPPER TROUGH TO MOVE SLOWLY THROUGH
WRN MT TONIGHT AND THROUGH ERN MT TUE. AT 18Z MODELS LOOKED PRETTY GOOD
WITH THEIR FORECAST POSITION OF THE SOUTHERN PORTION OF THIS UPPER
TROUGH BUT APPEARED TO BE TOO FAST WITH THE NORTHERN PORTION. THREAT OF
SEVERE WEATHER STILL LOOKS GOOD OVER EASTERN PLAINS OF MT WITH CAPES
NEAR 4000 JOULES/KILOGRAM AND LIFTED INDICES ON THE ORDER OF MINUS 10
TOWARDS ERN BORDER. DOES NOT APPEAR TO BE MUCH THREAT FOR SEVERE WEATHER
OVER LOCAL COUNTY WARNING AREA EXCEPT POSSIBLY ERN PORTIONS OF HVR AND
LWT ZONES. WILL GO WITH SCATTERED SHOWERS/THUNDERSTORMS THROUGH EARLY
EVENING OVER FORECAST AREA AHEAD OF UPPER TROUGH. DUE TO DOWNSLOPE WINDS
WILL GO DRY OVER NW PORTION BUT WILL LEAVE SOME SHOWERS IN THE
MOUNTAINS. AFTER TROUGH PASSAGE NW FLOW ALOFT SETS UP OVER STATE AND
MODELS IN AGREEMENT IN FORECASTING STABLE AIRMASS. ALTHOUGH A FEW MINOR
SHORTWAVES ARE FORECAST TO RIPPLE THROUGH NW FLOW ALOFT...MODELS DO NOT
FORECAST MUCH RH WITH THEM. SO WILL BE GOING DRY 2ND THROUGH 4TH
PERIODS. MODELS ALSO FORECAST MODERATE DOWNSLOPE GRADIENTS OVER PLAINS
SO WILL BE MENTIONING WEST WINDS IN APPROPRIATE ZONES. NGM/AVN MOS
TEMPERATURE GUIDANCE IN CLOSE AGREEMENT WITH ONE ANOTHER THROUGH FIRST
THREE PERIODS. GUIDANCE LOOKS PRETTY GOOD SO WILL NOT DEVIATE MUCH FROM
SAME. AVN WARMUP ON WED LOOKS OVERDONE CONSIDERING ITS FORECAST
THICKNESS CHANGES SO WILL STICK TO MORE CONSERVATIVE NGM GUIDANCE. BLANK
GTF 3000 HLN 3111 HVR 4000

Severe Thunderstorm Warnings in Montana, 1999Every severe thunderstorm warning in 1999

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; verification from NCEI's Storm Data; the sounding from the Mesonet's radiosonde archive.