Alert archive / Montana / Tornado Watches in 1998

Tornado Watch 439

May 26, 199820 counties in Montana

The Storm Prediction Center issued this tornado watch at May 26, 1998, 5:00 PM MDT for 20 counties in Montana. It was in force for 6 hr.

The area

The outline as issued.

The facts

Issued
May 26, 1998, 5:00 PM MDT (23:00 UTC)
Expired
May 26, 1998, 11:00 PM MDT
In force
6 hr
Issued by
the Storm Prediction Center

Counties Big Horn County, MT, Blaine County, MT, Carbon County, MT, Chouteau County, MT, Fergus County, MT, Garfield County, MT, Golden Valley County, MT, Hill County, MT, Judith Basin County, MT, Liberty County, MT, Musselshell County, MT, Petroleum County, MT, Phillips County, MT, Powder River County, MT, Rosebud County, MT, Stillwater County, MT, Toole County, MT, Treasure County, MT, Wheatland County, MT, Yellowstone County, MT

The radar

The Glasgow radar (KGGW), 162 km from the middle of the area, began a volume at 23:03 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.

The nearest sounding before it

Great_falls, MT (KTFX), launched 12:00Z, 11.0 hours before the alert went out and 164 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, Great_falls, MT at 12:00Z on 1998-05-26Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 6 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, Great_falls, MT at 12:00Z on 1998-05-26The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 10 square meters per square second.1939Sfc1 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
6 J/kg
Mixed-layer CIN
-328 J/kg
Mixed-layer LCL
1671 m above ground
0-6 km bulk shear
29 kt
0-1 km storm-relative helicity
10 m²/s²
0-3 km storm-relative helicity
37 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.

093 
WWUS9 KMKC 262238
SEL9  
MKC WW 262238
MTZ000-270500-

BULLETIN - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 439
STORM PREDICTION CENTER NORMAN OK
438 PM MDT TUE MAY 26 1998

THE STORM PREDICTION CENTER HAS ISSUED A
TORNADO WATCH FOR PORTIONS OF

   CENTRAL AND EASTERN MONTANA                            

EFFECTIVE THIS TUESDAY AFTERNOON AND EVENING FROM 500 PM UNTIL 1100
PM MDT.

TORNADOES...HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS
TO 80 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.

THE TORNADO WATCH AREA IS ALONG AND 105 STATUTE MILES EAST AND WEST
OF A LINE FROM 35 MILES NORTH NORTHWEST OF HAVRE MONTANA TO 90
MILES WEST SOUTHWEST OF BROADUS MONTANA.

REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR
TORNADOES AND SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH AREA. 
PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR THREATENING
WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS AND POSSIBLE
WARNINGS.

OTHER WATCH INFORMATION...  CONTINUE...WW 430...WW 431...WW
432...WW 433...WW 434...WW 435...WW 436...WW 437...WW 438...

DISCUSSION...THUNDERSTORMS...INCLUDING SUPERCELLS...LIKELY TO
SPREAD NWD THROUGH WATCH AREA THIS EVENING AHEAD OF STRONG SHORT
WAVE TROF EJECTING NWD FROM ID/WY.  BOUNDARY LAYER MOSITURE CONTENT
SOMEWHAT MARGINAL FOR LONG-LIVED TORNADOES /MIXED LAYER DEWPOINTS
IN THE UPPER 40/...BUT STRENGTH/DEGREE OF LOW-LEVEL VEERING WILL
LIKELY REMAIN QUITE FAVORABLE AS SURFACE LOW MOVES EWD INTO WATCH
REGION.

AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 2 INCHES.  EXTREME TURBULENCE AND SURFACE WIND
GUSTS TO 70 KNOTS.  A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 480. 
MEAN STORM MOTION VECTOR 18030.

...CORFIDI

490,1074 445,1045 445,1091 490,1122

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
May 26, 2:45 PM MDTSevere Thunderstorm WatchSPCBeaverhead, Broadwater, Cascade, Deer Lodge, Flathead, Gallatin and 15 more5 hr

Nearby

Tornado Watches in Montana, 1998Every tornado watch 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.