Alert archive / Montana / Flash Flood Warnings in 2002

Flash Flood Warning 11, NWS Glasgow, MT

August 21, 2002McCone County, Montana

NWS Glasgow, MT issued this flash flood warning at Aug 21, 2002, 2:44 AM MDT for McCone 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
Aug 21, 2002, 2:44 AM MDT (08:44 UTC)
Expired
Aug 21, 2002, 8:45 AM MDT
In force
6 hr
Issued by
NWS Glasgow, MT
Area
Whole counties

County McCone County, MT

The radar

The Glasgow radar (KGGW), 88 km from the middle of the area, began a volume at 08:43 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, 8.7 hours before the alert went out and 88 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, Glasgow Intl Airport, MT at 00:00Z on 2002-08-21Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 41 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, Glasgow Intl Airport, MT at 00:00Z on 2002-08-21The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 29 square meters per square second.19395878Sfc1 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
41 J/kg
Mixed-layer CIN
-403 J/kg
Mixed-layer LCL
2487 m above ground
0-6 km bulk shear
51 kt
0-1 km storm-relative helicity
29 m²/s²
0-3 km storm-relative helicity
182 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 
WGUS55 KGGW 210844
FFWGGW
MTC055-211445-

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE GLASGOW MT
241 AM MDT WED AUG 21 2002

THE NATIONAL WEATHER SERVICE IN GLASGOW HAS ISSUED A

* FLASH FLOOD WARNING FOR...
  NORTHWESTERN MCCONE COUNTY IN NORTHEAST MONTANA

* UNTIL 845 AM MDT

* AT 240 AM MDT...RADAR INDICTAED THUNDERSTORMS WITH VERY HEAVY
  RAINFALL IN EXTREME NORTHWESTERN MCCONE COUNTY...OR ABOUT 5
  MILES SOUTHEAST OF FORT PECK...MOVING EAST AT 10 MPH.

* 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 THE SPILLWAY OF FORT PECK DAM ON HIGHWAY 24
  AND...RURAL NORTHWESTERN MCCONE COUNTY

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 TO HIGHER GROUND TO ESCAPE FLOOD WATERS. DO NOT STAY
IN AREAS SUBJECT TO FLOODING WHEN WATER BEGINS RISING.

.END

79

What forecasters said that day

The local office's own words before this flash flood warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Glasgow, MT wrote its last area forecast discussion before this flash flood warning went out at Aug 21, 2:30 AM MDT, 14 minutes earlier.

Area forecast discussion, Aug 21, 2:30 AM MDT, 14 minutes before
NORTHEAST MONTANA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
230 AM MDT WED AUG 21 2002

.SHORT TERM...
UPPER LOW HAS CONSIDERABLY SLOWED DOWN...NOW OVER E OREGON...
PUTTING E MT IN A TREMENDOUS UPPER DIVERGENT PATTERN THIS MORNING. AS A
RESULT...SEVERE THUNDERSTORMS WITH HEAVY RAIN HAVE BROKEN OUT. THESE
STORMS HAVE BEEN NEARLY STATIONARY SINCE ABOUT MIDNIGHT...AND
FORTUNATELY OVER A VERY DESOLATE PORTION OF THE CWA. AN AREA ABOUT 20
MILES SOUTH OF GLASGOW...ACCORDING TO RADAR ESTIMATES HAS PICKED UP 11
INCHES OF RAIN.

THE BIGGEST QUESTION IS WHAT HAPPENS IN THE NEXT SEVERAL HOURS. DO THE
CURRENT STORMS LIFT OUT...OR DO THEY CONTINUE IN SCATTERED FASHION OVER
THE CWA?

OVER THE REMAINDER OF THE SHORT-TERM BOTH THE ETA AND AVN ARE IN
AGREEMENT WITH THE GENERAL UPPER PATTERN. THE UPPER LOW IS EXPECTED TO
WOBBLE INTO IDAHO TODAY...THEN WEAKEN AND DRIFT WEST BY THURSDAY.

THETA-E RIDGE IS EXPECTED TO GRADUALLY SHARPEN THROUGH FRIDAY WHILE
THE UPPER LEVEL FLOW IS EXPECTED TO REMAIN FROM THE SW. THEREFORE...
HAVE ADDED MENTION OF THUNDERSTORMS FOR THURSDAY AND FRIDAY ACROSS THE
CWA.

.LONG TERM...
MRF AND ECMWF IN AGREEMENT WITH UPPER LOW THAT IS NEARLY STATIONARY OVER
THE PACIFIC NW FINALLY PULLS OUT EARLY NEXT WEEK. CONFIDENCE IS LOW
THAT SATURDAY WILL REMAIN DRY WHILE A CHANCE OF THUNDERSTORMS FROM
SUNDAY THROUGH TUESDAY LOOKS GOOD AT THE MOMENT.

KGGW TBB /075 055/082 058/081 7643222
     BBBB 051/081 050/084 051/081 052/083 052/ 76223333333
KGDV TBB /082 058/084 058/084 7643222
     BBBB 052/082 050/083 050/082 051/084 051/ 76223333333

.GGW...NONE.

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 20, 11:23 PM MDTSevere Thunderstorm WarningGGWValley52 min
Aug 21, 12:18 AM MDTSevere Thunderstorm WarningGGWValley57 min
Aug 21, 12:35 AM MDTFlash Flood WarningGGWValley6 hr
Aug 21, 1:19 AM MDTSevere Thunderstorm WarningGGWValley56 min
Aug 21, 2:19 AM MDTSevere Thunderstorm WarningGGWMcCone, Valley56 min
Aug 21, 4:53 AM MDTSevere Thunderstorm WarningGGWMcCone67 min
Aug 21, 10:20 AM MDTFlash Flood WarningGGWValley6 hr

Nearby

Flash Flood Warnings in Montana, 2002Every flash flood 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.