Alert archive / Montana / Severe Thunderstorm Warnings in 2002

Severe Thunderstorm Warning 7, NWS Great Falls, MT

May 30, 2002Gallatin County, Montana

NWS Great Falls, MT issued this severe thunderstorm warning at May 30, 2002, 8:54 PM MDT for Gallatin County, Montana. It was in force for 36 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 30, 2002, 8:54 PM MDT (02:54 UTC)
Expired: May 30, 2002, 9:30 PM MDT
In force: 36 min
Issued by: NWS Great Falls, MT
Area: Counties, with a storm outline in the text

County Gallatin County, MT

What was reported inside it

Time	Report	Where	Remark
May 30, 9:00 PM MDT	Hail 0.75	Big Sky, MT	A severe thunderstorm produced 0.75 inch hail in Big Sky.

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.

Did it verify

Not verified. The Iowa Environmental Mesonet's Cow found no qualifying storm report inside this severe thunderstorm warning while it was in force. That is not proof nothing happened: reports are thin where few people live.

Cow counts a report within 15 km of the polygon while the warning was in force: a tornado for a tornado warning; hail of 1 inch or more, a gust of 58 mph or more or wind damage for a severe thunderstorm warning; a flash flood report for a flash flood warning.

The nearest sounding before it

Riverton, WY (KRIW), launched 00:00Z, 2.9 hours before the alert went out and 332 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: 13 J/kg
Mixed-layer CIN: -8 J/kg
Mixed-layer LCL: 3598 m above ground
0-6 km bulk shear: 31 kt
0-1 km storm-relative helicity: 6 m²/s²
0-3 km storm-relative helicity: 23 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.

954 
WUUS55 KTFX 310254
SVRTFX
MTC031-310330-

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE GREAT FALLS MT
853 PM MDT THU MAY 30 2002

THE NATIONAL WEATHER SERVICE IN GREAT FALLS HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  CENTRAL GALLATIN COUNTY IN SOUTHWEST MONTANA

* UNTIL 930 PM MDT

* AT 850 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A 
SEVERE THUNDERSTORM JUST WEST OF BIG SKY...OR ABOUT 32 MILES 
SOUTHWEST OF BOZEMAN...MOVING EAST AT 25 MPH.

* THE SEVERE THUNDERSTORM WILL BE NEAR...
  BIG SKY AT 900 PM MDT

THIS STORM HAS A HISTORY OF PRODUCING ONE INCH HAIL.

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 4534 11135 4520 11135 4520 11105 4534 11105
          4535 11093

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.

NWS Great Falls, MT wrote its last area forecast discussion before this severe thunderstorm warning went out at May 30, 8:15 PM MDT, 39 minutes earlier.

Area forecast discussion, May 30, 8:15 PM MDT, 39 minutes before

SOUTHWEST AND NORTH CENTRAL MONTANA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
815 PM MDT THU MAY 30 2002

.SHORT TERM...WILL UPDATE AROUND 9 PM TO FRESHEN WORDING. UNTIL
THEN...WILL KEEP AN EYE ON CONVECTIVE ACTION IN THE SOUTHWEST ZONES.
LOCALIZED MOISTURE POOL AND AREA OF SURFACE CONVERGENCE HELPING TO
DRIVE THIS SYSTEM INTO THE EVENING HOURS. CLOUD TOPS HAVE COOLED OVER
THE PAST HOUR...AND A CELL OR TWO HAS BECOME BORDERLINE SEVERE...SO
ACTIVITY MAY WELL LINGER AFTER THE SUN GOES DOWN. WILL FINE TUNE SKY
COVER OVER NORTHERN ZONES FOR TONIGHT...AS CLEAR SKIES ARE EXPECTED
OVER THE NORTHERN ZONES BY MIDNIGHT. TOMORROW SHOULD BE A REPEAT OF
TODAY WITH RESPECT TO TIMING AND LOCATION OF THUNDERSTORMS.
SATURDAY...INGREDIENTS MAY COME TOGETHER FOR SEVERE WEATHER IN THE
SOUTHWEST. MODEL SOUNDINGS INDICATING EXTREME LAPSE RATES...AND A
FAIRLY STRONG SHORTWAVE TO ARRIVE DURING TIME OF MAX HEATING. POMEROY

.EXTENDED...WEAK FLOW AT ALL LEVELS MONDAY...BUT ENOUGH LOW LEVEL
MOISTURE FOR SOME INSTABILITY AND SCATTERED THUNDERSTORMS. TUESDAY
FLOW TURNS NORTHWEST AHEAD OF WEAK RIDGE THAT WILL AFFECT THE REGION
WEDNESDAY AND MOST OF THURSDAY. SHORTWAVE MOVES INTO WESTERN MONTANA
THURSDAY...BUT FOR NOW WILL LEAVE FORECAST DRY. POMEROY

.CCF NUMBERS
GTF BE 049/079 047/076 044 14000
    TEBBB 068/043 068/045 071/046 075/049 071 25333322222
CTB BE 046/076 043/071 041 14000
    TEBBB 066/039 066/041 069/043 073/045 067 25333322222
HLN BT 050/083 048/076 046 14111
    TEBBB 068/043 072/045 074/046 079/049 076 35333332222
BZN BT 050/083 048/076 046 14322
    BEBBB 068/043 065/042 069/042 075/042 075 45233332222
WEY BT 040/075 040/070 035 14322
    BWBBB 060/033 059/032 061/035 065/035 062 45244332222
DLN BT 050/081 048/074 042 14222
    BEBBB 068/043 065/042 069/042 075/044 071 45233332222
HVR BE 050/082 048/079 046 14000
    REBBB 070/045 069/045 075/048 076/049 071 25533322222
LWT BE 047/078 045/074 043 14000
    REBBB 067/043 068/045 071/046 075/049 071 25533322222=

.TFX...NONE.

The office that day

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

Issued	Product	Office	Counties	Lasted
May 30, 8:29 PM MDT	Severe Thunderstorm Warning	TFX	Madison	46 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.