Alert archive / Montana / Severe Thunderstorm Warnings in 2002

Severe Thunderstorm Warning 66, NWS Great Falls, MT

July 16, 2002Fergus County, Montana

NWS Great Falls, MT issued this severe thunderstorm warning at Jul 16, 2002, 6:20 PM MDT for Fergus County, Montana. It was in force for 40 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: Jul 16, 2002, 6:20 PM MDT (00:20 UTC)
Expired: Jul 16, 2002, 7:00 PM MDT
In force: 40 min
Issued by: NWS Great Falls, MT
Area: Counties, with a storm outline in the text

County Fergus County, MT

The radar

The Glasgow radar (KGGW), 163 km from the middle of the area, began a volume at 00:21 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
Jul 16, 6:22 PM MDT	Hail 0.75	Valentine, MT	A severe thunderstorm produced 0.75 inch hail at Valentine.

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

Great_falls, MT (KTFX), launched 00:00Z, 0.3 hours before the alert went out and 163 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: 979 J/kg
Mixed-layer CIN: -36 J/kg
Mixed-layer LCL: 2388 m above ground
0-6 km bulk shear: 34 kt
0-1 km storm-relative helicity: 27 m²/s²
0-3 km storm-relative helicity: 80 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 2.4

Open this sounding in Storm Lab

The text

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

717 
WUUS55 KTFX 170020
SVRTFX
MTC027-170045-

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE GREAT FALLS MT
619 PM MDT TUE JUL 16 2002

THE NATIONAL WEATHER SERVICE IN GREAT FALLS HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  EXTREME EAST CENTRAL FERGUS COUNTY IN CENTRAL MONTANA

* UNTIL 700 PM MDT

* AT 615 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  SEVERE THUNDERSTORM OVER EXTREME EAST CENTRAL FERGUS COUNTY...OR
  ABOUT 25 MILES NORTH OF WINNETT...MOVING NORTHEAST AT 15 MPH.

* THE SEVERE THUNDERSTORM WILL REMAIN OVER...
RURAL EASTERN FERGUS COUNTY THROUGH 700 PM MDT

LARGE HAIL AND STRONG WINDS ARE 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.

LAT...LON 4739 10866 4723 10855 4735 10809 4755 10822

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 Jul 16, 3:00 PM MDT, 3 hours 20 minutes earlier.

Area forecast discussion, Jul 16, 3:00 PM MDT, 3 hours 20 minutes before

SOUTHWEST AND NORTH CENTRAL MONTANA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
300 PM MDT TUE JUL 16 2002

.SHORT TERM...ANOTHER EVENING OF SCATTERED CONVECTION IS IN STORE
FOR THE SOUTHERN HALF OF MY CWA. SPC HAS DOWNGRADED THE SLIGHT RISK
AREA FOR THE STATE...BUT STILL EXPECTS ISOLATED SEVERE STORMS TO
DEVELOP...WITH LARGE HAIL BEING THE PRIMARY THREAT. FORECAST
SOUNDINGS INDICATE THAT WET-BULB ZERO HEIGHT MAY BE A BIT HIGH...
WITH WIND SHEAR REMAINING RELATIVELY WEAK...SO ISOLATED SEVERE
THREAT SEEMS TO BE A CORRECT ASSESSMENT. FOR WEDNESDAY THROUGH
THURSDAY NIGHT...THE AIRMASS OVER THE STATE REMAINS UNSTABLE WITH
DEWPOINTS IN THE MID 50S. HOWEVER...A MID AND UPPER LEVEL RIDGE
BUILDS OVER WESTERN MONTANA. BELIEVE THIS RIDGE...AND LACK OF ANY
DECENT UPPER LEVEL DYNAMICS OVER MY CWA...WILL LIMIT CONVECTIVE
ACTIVITY. HAVE BROAD-BRUSHED ISOLATED POPS FOR MY ENTIRE CWA
THROUGH THURSDAY NIGHT. ON FRIDAY...THE AVN BEGINS TO MOVE AN UPPER
LEVEL TROUGH INLAND OVER THE PACIFIC NW...WITH SEVERAL SHORTWAVE
APPROACHING WESTERN MT BY AFTERNOON. WILL INCREASE POPS TO CHANCE
CATEGORY FOR WESTERN HALF OF MY CWA...BUT KEEP ISOLATED POPS IN THE
EAST. TEMPERATURES WILL REMAIN ABOVE NORMAL THROUGH FRIDAY. COULD
SEE A SLIGHT COOL DOWN ON FRIDAY AS THE AFOREMENTIONED UPPER TROUGH
APPROACHES THE CWA...BUT WOULD NOT BE SURPRISED TO SEE THE MODELS
BACK OFF ON THIS TREND IN FUTURE MODEL RUNS. MPJ

.EXTENDED...ONCE AGAIN THERE ARE BIG DIFFERENCES BETWEEN THE ECMWF
AND AVN DURING THE PERIOD. LIKE FOR MON THE 00Z AVN RUN HAS AN UPPER
TROUGH SWEEPING THROUGH WRN CAN WITH ITS SRN PORTION AFFECTING AT
LEAST THE NRN ZONES. HOWEVER THE 00Z TUE RUN OF THE AVN IS NOT AS
STRONG WITH THE UPPER TROUGH AND THE 12Z TUE RUN OF THE AVN DOES
NOT EVEN HAVE THE UPPER TROUGH. ECMWF HAS BEEN CONSISTENT IN
FORECASTING AN UPPER RIDGE OVER THE WRN U.S. DURING THE PERIOD. 12Z
TUE RUN OF THE UKMET APPEARS TO BE MORE LIKE THE ECMWF. NCEP FAVORS
A BLEND OF THE AVN/ECMWF SOLUTIONS BUT STILL PREFER A SOLUTION MORE
LIKE THE ECMWF. WILL GO WITH THE AVN FOR THE EARLY PART OF THE
EXTENDED AND WILL GO WITH CHANCE TO SLIGHT CHANCE POPS FOR FRI NIGHT
INTO SAT. FOR SUN THROUGH MON UPPER RIDGE AXIS COULD BE UPSTREAM OF
AREA WHICH WOULD TEND TO KEEP AREA DRY. HARD TO SAY WHAT GENERAL
PATTERN WILL BE FOR TUE MUCH LESS WHAT THE DETAILS WILL BE. WILL
LEAN TOWARDS CLIMATOLOGY WITH SLIGHT CHANCE POPS. BLANK

.CCF NUMBERS
GTF BB 063/094 061/095 058 14412
    BBBBB 088/056 086/055 088/056 090/056 090 22322111112
CTB BB 059/092 058/091 055 14112
    BBBBB 085/052 083/052 084/052 087/052 087 22221111112
HLN BB 062/094 060/095 058 14423
    BBBBB 088/057 088/056 089/057 090/057 090 22332111222
BZN BB 058/091 055/091 053 14622
    BEBBB 087/055 086/052 086/053 088/053 088 22333111222
WEY BB 051/088 050/087 048 14622
    BEBBB 082/045 080/043 080/044 082/044 082 22333111222
DLN BB 057/090 055/089 054 14522
    BBBBB 086/053 085/051 086/052 087/052 087 22332111222
HVR BB 064/096 063/096 059 14512
    BBBBB 090/059 088/056 089/056 091/056 091 22222111112
LWT BB 061/089 059/090 056 14622
    BEBBB 087/055 085/054 086/055 088/055 088 22233111112=

.TFX...NONE

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 16, 6:27 PM MDT	Severe Thunderstorm Warning	TFX	Fergus	33 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.