Alert archive / Montana / Severe Thunderstorm Warnings in 2002

Severe Thunderstorm Warning 2, NWS Great Falls, MT

May 21, 2002Judith Basin County, Montana

NWS Great Falls, MT issued this severe thunderstorm warning at May 21, 2002, 4:26 PM MDT for Judith Basin County, Montana. It was in force for 34 min. 1 report came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued: May 21, 2002, 4:26 PM MDT (22:26 UTC)
Expired: May 21, 2002, 5:00 PM MDT
In force: 34 min
Issued by: NWS Great Falls, MT
Area: Counties, with a storm outline in the text

County Judith Basin County, MT

The radar

The Great Falls radar (KTFX), 92 km from the middle of the area, began a volume at 22:29 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.

What was reported inside it

Time	Report	Where	Remark
May 21, 4:45 PM MDT	Hail 0.75	Windham, MT	A severe thunderstorm produced 0.75 inch hail near Windham.

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.

The watch it was issued in

The SPC watch in force over the same counties when this warning went out.

Issued	Product	Office	Lasted
May 21, 3:45 PM MDT	Tornado Watch	SPC	5 hr

The nearest sounding before it

Great_falls, MT (KTFX), launched 12:00Z, 10.4 hours before the alert went out and 44 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 1038 m above ground
0-6 km bulk shear: 47 kt
0-1 km storm-relative helicity: 7 m²/s²
0-3 km storm-relative helicity: 189 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.2

Open this sounding in Storm Lab

The text

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

000 
WUUS55 KTFX 212226
SVRGTF
MTC045-212300-

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE GREAT FALLS MT
425 PM MDT TUE MAY 21 2002

THE NATIONAL WEATHER SERVICE IN GREAT FALLS HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  NORTHEASTERN JUDITH BASIN COUNTY IN CENTRAL MONTANA

* UNTIL 500 PM MDT

* AT 425 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED
  A SEVERE THUNDERSTORM 12 MILES WEST OF BENCHLAND MOVING NORTH AT 
  40 MPH.

* THE SEVERE THUNDERSTORM WILL BE NEAR...
GEYSER AND STANFORD BY 445 PM MDT

A TORNADO WATCH REMAINS IN EFFECT UNTIL 900 PM MDT TUESDAY EVENING
FOR NORTH CENTRAL MONTANA.

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

LAT...LON 4703 11042 4689 11004 4709 10979 4740 11036
          4740 11056

The office that day

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

Issued	Product	Office	Counties	Lasted
May 20, 7:17 PM MDT	Severe Thunderstorm Warning	TFX	Teton	28 min

Nearby

Severe Thunderstorm Warnings in Montana, 2002 Every severe thunderstorm warning in 2002

Sources

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; radar from the NEXRAD Level II archive.