Alert archive / Montana / Severe Thunderstorm Warnings in 1998

Severe Thunderstorm Warning 99, NWS Great Falls, MT

September 18, 1998Chouteau County, Teton County, Montana

NWS Great Falls, MT issued this severe thunderstorm warning at Sep 18, 1998, 3:35 PM MDT for Chouteau County, Teton County, Montana. It was in force for 50 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
Sep 18, 1998, 3:35 PM MDT (21:35 UTC)
Expired
Sep 18, 1998, 4:25 PM MDT
In force
50 min
Issued by
NWS Great Falls, MT
Area
Whole counties

Counties Chouteau County, MT, Teton County, MT

The radar

The Great Falls radar (KTFX), 45 km from the middle of the area, began a volume at 21:38 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

The nearest sounding before it

Great_falls, MT (KTFX), launched 12:00Z, 9.6 hours before the alert went out and 71 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 1998-09-18Temperature 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, Great_falls, MT at 12:00Z on 1998-09-18The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 14 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
859 m above ground
0-6 km bulk shear
40 kt
0-1 km storm-relative helicity
14 m²/s²
0-3 km storm-relative helicity
45 m²/s²
Significant tornado parameter
0.0
Supercell composite
-0.1

Open this sounding in Storm Lab

The text

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

000 
TTAA00 KGTF 182135 RRA
SVRGTF
MTC015-099-182225-

BULLETIN - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE GREAT FALLS MT
335 PM MDT FRI SEP 18 1998


THE NATIONAL WEATHER SERVICE HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  WESTERN CHOUTEAU COUNTY IN NORTH CENTRAL MONTANA
  EASTERN TETON COUNTY IN NORTHWESTERN MONTANA

* UNTIL 425 PM MDT

* AT 333 PM MDT... DOPPLER RADAR AT GREAT FALLS INDICATED A SEVERE
  THUNDERSTORM 33 MILES EAST OF CHOTEAU OR 22 MILES NORTHWEST OF
  FLOWEREE MOVING EAST AT 25 MPH.

* SOME LOCATIONS IN OR NEAR THE PATH OF THIS STORM ARE...
  FLOWEREE.

The office that day

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

IssuedProductOfficeCountiesLasted
Sep 18, 2:32 PM MDTSevere Thunderstorm WarningTFXGallatin33 min
Sep 18, 2:49 PM MDTSevere Thunderstorm WarningTFXJudith Basin51 min
Sep 18, 4:37 PM MDTSevere Thunderstorm WarningTFXChouteau, Liberty38 min

Nearby

Severe Thunderstorm Warnings in Montana, 1998Every severe thunderstorm warning in 1998

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; radar from the NEXRAD Level II archive.