Alert archive / Montana / Flash Flood Warnings in 2001

Flash Flood Warning 21, NWS Glasgow, MT

July 20, 2001Dawson County, Prairie County, Montana

NWS Glasgow, MT issued this flash flood warning at Jul 20, 2001, 8:35 PM MDT for Dawson County, Prairie County, Montana. It was in force for 6 hr. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued: Jul 20, 2001, 8:35 PM MDT (02:35 UTC)
Expired: Jul 21, 2001, 2:30 AM MDT
In force: 6 hr
Issued by: NWS Glasgow, MT
Area: Whole counties

Counties Dawson County, MT, Prairie County, MT

The radar

The Glasgow radar (KGGW), 169 km from the middle of the area, began a volume at 02:38 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

Glasgow Intl Airport, MT (KGGW), launched 00:00Z, 2.6 hours before the alert went out and 169 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: 996 J/kg
Mixed-layer CIN: -183 J/kg
Mixed-layer LCL: 1651 m above ground
0-6 km bulk shear: 52 kt
0-1 km storm-relative helicity: 331 m²/s²
0-3 km storm-relative helicity: 373 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 3.6

Open this sounding in Storm Lab

The text

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

000 
WGUS55 KGGW 210236
FFWGGW
MTC021-079-210830-

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE GLASGOW MT
835 PM MDT FRI JUL 20 2001

THE NATIONAL WEATHER SERVICE IN GLASGOW HAS ISSUED A

* FLASH FLOOD WARNING FOR...
  DAWSON COUNTY IN NORTHEAST MONTANA
  PRAIRIE COUNTY IN NORTHEAST MONTANA

* UNTIL 230 AM MDT

* AT 828 PM MDT...LAW ENFORCEMENT REPORTED THUNDERSTORMS WITH 
  VERY HEAVY RAINFALL IN DAWSON AND PRAIRIE COUNTY

* SLOW MOVING THUNDERSTORMS ARE PRODUCING TORRENTIAL RAINFALL IN THE
  WARNED AREA. RUNOFF FROM THIS EXCESSIVE RAINFALL WILL CAUSE FLASH
  FLOODING TO OCCUR. SOME LOCATIONS THAT WILL EXPERIENCE FLASH
  FLOODING INCLUDE...FALLON AND MILDRED

LAW ENFORCEMENT REPORTED WATER RUNNING ACROSS GRAVEL ROADS IN BOTH 
COUNTIES.

BE ESPECIALLY CAUTIOUS AT NIGHT WHEN IT IS HARDER TO RECOGNIZE THE
DANGERS OF FLOODS AND FLASH FLOODS. IF FLASH FLOODING IS OBSERVED ACT
QUICKLY. MOVE UP TO0 HIGHER GROUND TO ESCAPE FLOOD WATERS. DO NOT STAY
IN AREAS SUBJECT TO FLOODING WHEN WATER BEGINS RISING.

.END
88

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 20, 6:15 PM MDT	Tornado Warning	GGW	McCone	60 min
Jul 20, 6:28 PM MDT	Flash Flood Warning	GGW	Garfield, McCone	3 hr
Jul 20, 6:41 PM MDT	Severe Thunderstorm Warning	GGW	Sheridan	64 min
Jul 20, 6:56 PM MDT	Tornado Warning	GGW	Dawson	64 min
Jul 20, 7:09 PM MDT	Severe Thunderstorm Warning	GGW	Richland	66 min
Jul 20, 7:15 PM MDT	Severe Thunderstorm Warning	GGW	McCone	60 min
Jul 20, 7:24 PM MDT	Severe Thunderstorm Warning	GGW	Roosevelt	66 min
Jul 20, 7:25 PM MDT	Severe Thunderstorm Warning	GGW	Prairie	65 min
Jul 20, 7:57 PM MDT	Tornado Warning	GGW	Dawson	63 min
Jul 20, 8:14 PM MDT	Tornado Warning	GGW	Richland	61 min
Jul 20, 8:30 PM MDT	Severe Thunderstorm Warning	GGW	Prairie	60 min
Jul 20, 8:43 PM MDT	Tornado Warning	GGW	Wibaux	62 min
Jul 20, 9:27 PM MDT	Severe Thunderstorm Warning	GGW	Dawson	63 min
Jul 20, 10:15 PM MDT	Severe Thunderstorm Warning	GGW	Wibaux	60 min
Jul 21, 5:23 PM MDT	Severe Thunderstorm Warning	GGW	Phillips	67 min

Nearby

Flash Flood Warnings in Montana, 2001 Every flash flood warning in 2001

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.