Alert archive / Montana / Severe Thunderstorm Warnings in 1998

Severe Thunderstorm Warning 51, NWS Missoula, MT

August 22, 1998Lake County, Missoula County, Montana

NWS Missoula, MT issued this severe thunderstorm warning at Aug 22, 1998, 1:37 AM MDT for Lake County, Missoula County, Montana. It was in force for 58 min. 2 reports came from inside the area while it was in force.

The area

The counties it named, with what was reported inside it.

The facts

Issued
Aug 22, 1998, 1:37 AM MDT (07:37 UTC)
Expired
Aug 22, 1998, 2:35 AM MDT
In force
58 min
Issued by
NWS Missoula, MT
Area
Whole counties

Counties Lake County, MT, Missoula County, MT

The radar

The Missoula radar (KMSX), 33 km from the middle of the area, began a volume at 07:39 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

TimeReportWhereRemark
Aug 22, 1:40 AM MDTHail 0.75(Mso)Missoula Intl A, MT
Aug 22, 1:45 AM MDTThunderstorm Wind 50Arlee, MT

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 nearest sounding before it

Spokane, WA (KOTX), launched 00:00Z, 7.6 hours before the alert went out and 184 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, Spokane, WA at 00:00Z on 1998-08-22Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 385 joules per kilogram.LCLLFCEL10008507005003002001001 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, Spokane, WA at 00:00Z on 1998-08-22The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -5 square meters per square second.193958Sfc1 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
385 J/kg
Mixed-layer CIN
-104 J/kg
Mixed-layer LCL
2636 m above ground
0-6 km bulk shear
19 kt
0-1 km storm-relative helicity
-5 m²/s²
0-3 km storm-relative helicity
2 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.

000 
TTAA00 KMSO 220736 RRA
SVRMSO
MTC047-063-220835-

BULLETIN - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE MISSOULA MT
137 AM MDT SAT AUG 22 1998

THE NATIONAL WEATHER SERVICE HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  EXTREME SOUTHERN LAKE COUNTY IN WEST CENTRAL MONTANA
  CENTRAL MISSOULA COUNTY IN WEST CENTRAL MONTANA

* UNTIL 235 AM MDT

* AT 130 AM MDT...SEVERE THUNDERSTORM INDICATED 5 MILES WEST OF
  MISSOULA...BY NATIONAL WEATHER SERVICE DOPPLER RADAR...MOVING
  NORTHEAST AT 20 MPH.

* SEVERE THUNDERSTORM WILL BE NEAR...
  DOWNTOWN MISSOULA AT 140 AM MDT
  EVARO AT 145 AM MDT
  ARLEE AT 150 AM MDT

HAIL TO 3/4 INCH OBSERVED AT MISSOULA AIRPORT

DESTRUCTIVE H~AIL...DAMAGING WINDS...DEADLY LIGHTNING...AND VERY
HEAVY RAIN ARE ALL LIKELY WITH THIS STORM. FOR YOUR PROTECTION...
MOVE INSIDE A STRONG BUILDING...AND STAY AWAY FROM WINDOWS. DO NOT
DRIVE INTO AREAS WHERE WATER COVERS THE ROAD.

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 Missoula, MT wrote its last area forecast discussion before this severe thunderstorm warning went out at Aug 21, 8:30 PM MDT, 5 hours 7 minutes earlier.

Area forecast discussion, Aug 21, 8:30 PM MDT, 5 hours 7 minutes before
WESTERN MONTANA AND NORTH CENTRAL IDAHO FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
830 PM MDT FRI AUG 21 1998

UPPER LEVEL TROF OVER THE PACIFIC NORTHWEST ROTATING A FEW VORT MAXES
THROUGH IDAHO AND WESTERN MONTANA THIS EVENING. THERMAL TROF OVER THE
ZONES WILL SHIFT INTO EASTERN MONTANA ON SATURDAY...HOWEVER AIR MASS
REMAINS MOIST AND UNSTABLE THROUGH FORECAST PERIOD FOR MONTANA ZONES.
WOULD NOT BE SURPRISED TO SEE ISOLATED AFTERNOON TSTMS DEVELOP IN
THESE ZONES AGAIN ON SATURDAY. WILL LOWER POPS AT BTM AND SMN AS TSTM
ACTIVITY PUSHES NORTHEAST OVERNIGHT. ON THE OTHER HAND...STILL A WEAK
BOUNDARY ZONE OVER CENTRAL IDAHO SO HAVE BUMP POPS UP SLIGHTLY AT S80
AND P69. PLAN ON UPDATE. HARMER

...FORECASTS BELOW ARE PRELIMINARY AND SUBJECT TO CHANGE...

LIB .. 047/080 047/080 ... 323202
FCA BB 049/083 048/081 051 323202
POL .. 054/082 055/081 ... 323101
MSO AB 051/085 052/082 053 322101
HMM .. 053/086 053/084 ... 322101
BTM .. 046/082 050/081 ... 324101
S80 .. 052/084 052/083 ... 322001
P69 .. 052/088 053/086 ... 322001
SMN .. 049/083 049/082 ... 321001

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; verification from NCEI's Storm Data; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.