Alert archive / Montana / Severe Thunderstorm Warnings in 2002

Severe Thunderstorm Warning 91, NWS Great Falls, MT

August 5, 2002Judith Basin County, Montana

NWS Great Falls, MT issued this severe thunderstorm warning at Aug 5, 2002, 5:52 PM MDT for Judith Basin County, Montana. It was in force for 38 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: Aug 5, 2002, 5:52 PM MDT (23:52 UTC)
Expired: Aug 5, 2002, 6:30 PM MDT
In force: 38 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), 58 km from the middle of the area, began a volume at 23:53 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
Aug 5, 5:57 PM MDT	Hail 4	Raynesford, MT	A severe thunderstorm produced 4.00 inch hail at Raynesford 4E.

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 watch it was issued in

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

Issued	Product	Office	Lasted
Aug 5, 3:55 PM MDT	Severe Thunderstorm Watch	SPC	6 hr

The nearest sounding before it

Great_falls, MT (KTFX), launched 12:00Z, 11.9 hours before the alert went out and 17 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: 992 m above ground
0-6 km bulk shear: 44 kt
0-1 km storm-relative helicity: 135 m²/s²
0-3 km storm-relative helicity: 308 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.5

Open this sounding in Storm Lab

The text

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

134 
WUUS55 KTFX 052352
SVRTFX
MTC045-060030-

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE GREAT FALLS MT
552 PM MDT MON AUG 5 2002

THE NATIONAL WEATHER SERVICE IN GREAT FALLS HAS ISSUED A

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

* UNTIL 630 PM MDT

* AT 548 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  SEVERE THUNDERSTORM 10 MILES SOUTHWEST OF GEYSER...OR ABOUT 23
  MILES WEST OF STANFORD...MOVING NORTHEAST AT 25 MPH.

* THE SEVERE THUNDERSTORM WILL BE NEAR...
  GEYSER AT 605 PM MDT

VERY LARGE HAIL IS POSSIBLE WITH THIS SEVERE THUNDERSTORM. IF YOU ARE
IN THE PATH OF THE STORM...PUT YOUR CAR IN A GARAGE AND MOVE TO A
SUBSTANTIAL SHELTER.

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 1000 PM MDT
MONDAY EVENING FOR WESTERN MONTANA.

LAT...LON 4724 11076 4714 11071 4741 11023 4741 11054
          4741 11064 4735 11064 4735 11075 4727 11077

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 Aug 5, 3:00 PM MDT, 2 hours 52 minutes earlier.

Area forecast discussion, Aug 5, 3:00 PM MDT, 2 hours 52 minutes before

SOUTHWEST AND NORTH CENTRAL MONTANA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
300 PM MDT MON AUG 5 2002

.SHORT TERM...SOUTHWEST PORTION OF CWA HAS SEEN AMPLE SUNSHINE
THIS AFTERNOON AND INITIAL CONVECTION SHOULD BEGIN THERE. THESE
STORMS WILL ADVANCE IN SWIFT SOUTHWEST FLOW ALOFT INTO SHEAR
ENVIRONMENT OVER THE NORTHERN PART OF THE CWA WHICH IS PROGGED TO BE
QUITE HIGH THIS EVENING. HELICITY...CAPE AND LI VALUES INDICATE THE
BEST POTENTIAL FOR SEVERE WEATHER IS EAST OF A LINE FROM NEAR GREAT
FALLS TO CHESTER.  SPC MODERATE RISK CALLS FOR LONG LIVED SUPERCELLS
WITH GREATEST THREAT FROM LARGE HAIL. HELICITY VALUES AND INSTABILITY
SUGGEST ROTATING UPDRAFTS ARE LIKELY. WILL PLAY THIS SCENARIO UP IN
AFTERNOON PACKAGE. SPS ISSUED EARLIER TODAY AS A HAZARDOUS WEATHER
OUTLOOK TO ATTRACT MEDIA ATTENTION FOR POSSIBLE SEVERE WEATHER
OUTBREAK.

MAIN UPPER LOW STILL OVER PACNW AND WILL CONTINUE TO SEND SHORT WAVE
ENERGY THROUGH A MOIST SOUTHWEST FLOW THROUGH WEDNESDAY. MODELS
CONTINUE ADVANCING PARENT LOW EAST AND WILL CONTINUE TO PLAY IT A BIT
SLOWER THAN PROGGED. BOTTOM LINE...WILL KEEP SCATTERED POPS IN FOR
MOST OF CWA THROUGH MOST OF PERIOD. DITTMANN

.EXTENDED...AVN/ECMWF ARE IN PRETTY GOOD AGREEMENT FOR FRI AND SAT
BUT DIVERGE SIGNIFICANTLY BY SUN. 12Z UKMET LEANS TOWARDS THE
00Z/12Z AVN. FOR FRI AND SAT LOOKS LIKE DRY W TO NW FLOW ALOFT WILL
BE OVER THE AREA. SUN AVN BRINGS AN UPPER TROUGH INTO THE AREA
WHILE THE ECMWF HAS AN UPPER RIDGE. ON MON 00Z AVN RUN DUG THE UPPER
TROUGH INTO ERN MT WITH COOL THICKNESSES FOR THE AREA. NCEP
DISCUSSION FAVORS A SLOWER AND LESS AMPLIFIED UPPER TROUGH THAN WHAT
THE 00Z/12Z AVN HAVE. SO WHEREAS THE 00Z AVN BROUGHT A COLD FRONT
THROUGH THE AREA ON SUN WILL HOLD OFF ON COLD FRONTAL PASSAGE UNTIL
MON. HARD TO SAY AT THIS POINT HOW MUCH MOISTURE AND WHETHER
THERE WILL BE MUCH IF ANY UPSLOPE FLOW WITH THE UPPER TROUGH.
WILL GO WITH A SLIGHT CHANCE OF SHOWERS FOR NOW. BLANK

.CCF NUMBERS
GTF BB 052/077 050/074 048 02533
    EBNNB 075/052 077/050 083/053 083/050 078 33321111112
CTB BB 048/070 047/069 045 02433
    BBNNB 071/048 076/048 080/050 077/046 072 22221111122
HLN BB 052/078 050/076 050 02533
    EBBNB 076/050 076/050 085/054 085/053 080 33421111112
BZN BB 048/080 046/078 048 02533
    EBBBB 078/044 074/045 082/048 084/047 080 33431111112
WEY BB 040/072 038/070 040 02333
    EBBBB 070/038 068/036 075/038 077/039 075 34541111112
DLN BB 048/078 046/076 046 02333
    BBBNB 075/044 075/044 080/047 082/049 080 33431111112
HVR BB 056/082 053/078 050 02633
    BBBNB 079/050 078/050 085/054 084/054 077 33311111122
LWT BB 052/080 050/076 047 02633
    EBBNB 074/047 073/045 081/050 081/050 077 33321111112=

.TFX...

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 4, 7:02 PM MDT	Severe Thunderstorm Warning	TFX	Fergus, Judith Basin	58 min
Aug 5, 5:16 PM MDT	Severe Thunderstorm Warning	TFX	Lewis and Clark	44 min
Aug 5, 5:36 PM MDT	Severe Thunderstorm Warning	TFX	Lewis and Clark	54 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.