Alert archive / Montana / Areal Flood Warnings in 2012

Areal Flood Warning 8, NWS Missoula, MT

April 26, 2012Ravalli County, Montana

NWS Missoula, MT issued this areal flood warning at Apr 26, 2012, 11:11 AM MDT for Ravalli County, Montana. It was in force for 48 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: Apr 26, 2012, 11:11 AM MDT (17:11 UTC)
Expired: Apr 28, 2012, 10:41 AM MDT
In force: 48 hr
Issued by: NWS Missoula, MT
Area: Storm-based polygon
Flood severity: None

County Ravalli County, MT

The radar

The Missoula radar (KMSX), 107 km from the middle of the area, began a volume at 17:10 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

Spokane, WA (KOTX), launched 12:00Z, 5.2 hours before the alert went out and 250 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: 18 J/kg
Mixed-layer CIN: -40 J/kg
Mixed-layer LCL: 753 m above ground
0-6 km bulk shear: 51 kt
0-1 km storm-relative helicity: 214 m²/s²
0-3 km storm-relative helicity: 230 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this areal flood 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 areal flood warning went out at Apr 26, 10:13 AM MDT, 58 minutes earlier.

Area forecast discussion, Apr 26, 10:13 AM MDT, 58 minutes before

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE MISSOULA MT
1013 AM MDT THU APR 26 2012

.UPDATE...ISSUED A SNOW ADVISORY FOR THE WEST GLACIER REGION FOR FRIDAY
MORNING THROUGH SATURDAY MORNING.

.DISCUSSION...SNOW LEVELS WILL QUICKLY DROP OVERNIGHT TONIGHT AND
SLUSHY SNOW ACCUMULATIONS ARE EXPECTED ON HIGHWAY 2 THROUGH
FRIDAY.

&&

.AVIATION...SHOWERS WITH FREQUENT REDUCTIONS IN VISIBILITY AND
PERSISTENTLY LOWERED CLOUDS WILL PREVAIL THROUGH THE NEXT 24 HOURS
AS A LARGE WEATHER SYSTEM AFFECTS THE NORTHERN ROCKIES. A STRONG
FROPA IS ANTICIPATED THIS AFTERNOON WHICH WILL BRING A BURST OF
HEAVY PRECIPITATION ALONG WITH A FEW HOURS OF VERY GUSTY WINDS.
FROPA WILL BE LEAST FELT AT KGPI BETWEEN 22Z AND 23Z BUT MORE
SIGNIFICANTLY EXPERIENCED AT KMSO NEAR 23Z...KBTM BETWEEN 01Z AND
02Z AND KSMN 03Z.

&&

.PREV DISCUSSION... /ISSUED 825 AM MDT THU APR 26 2012/

UPDATE...ISSUED WIND ADVISORIES FOR THE
FLATHEAD/MISSION...MISSOULA/BITTERROOT VALLEYS AND THE I-90
CORRIDOR FROM GARRISON JUNCTION TO BUTTE.

DISCUSSION...MODELS ARE INDICATING STRONG PRESSURE RISES BEHIND
THE COLD FRONT LATE THIS AFTERNOON AND EVENING...AND HAVE BEEN
TRENDING UPWARD. A BRIEF PERIOD OF STRONG WINDS GUSTING OVER 40
MPH IS LIKELY WITH FRONTAL PASSAGE...HOWEVER WINDS CONTINUING AT
ADVISORY LEVEL THROUGH THE NIGHT IS BORDERLINE CONSIDERING THAT
THE PRECIPITATION USUALLY REDUCES THE EXPECTED WINDS.

AVIATION...SHOWERS WITH FREQUENT REDUCTIONS IN VISIBILITY AND
PERSISTENTLY LOWERED CLOUDS WILL PREVAIL THROUGH THE NEXT 24 HOURS
AS A LARGE WEATHER SYSTEM AFFECTS THE NORTHERN ROCKIES. A STRONG
FROPA IS ANTICIPATED THIS AFTERNOON WHICH WILL BRING A BURST OF
HEAVY PRECIPITATION ALONG WITH A FEW HOURS OF VERY GUSTY WINDS.
FROPA WILL BE LEAST FELT AT KGPI BETWEEN 22Z AND 23Z BUT MORE
SIGNIFICANTLY EXPERIENCED AT KMSO NEAR 23Z...KBTM BETWEEN 01Z AND
02Z AND KSMN 03Z.

&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...WIND ADVISORY FROM 4 PM THIS AFTERNOON TO 4 AM MDT FRIDAY
     BUTTE/BLACKFOOT REGION.

     WIND ADVISORY FROM 4 PM THIS AFTERNOON TO 4 AM MDT FRIDAY
     MISSOULA/BITTERROOT VALLEYS.

     WIND ADVISORY FROM 4 PM THIS AFTERNOON TO 4 AM MDT FRIDAY
     FLATHEAD/MISSION VALLEYS.

     WINTER WEATHER ADVISORY FROM 6 AM FRIDAY TO 6 AM MDT SATURDAY
     WEST GLACIER REGION.

ID...NONE.
&&

SHORT TERM...KITSMILLER/LEACH
AVIATION...KITSMILLER

The office that day

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

Issued	Product	Office	Counties	Lasted
Apr 26, 8:12 AM MDT	Wind Advisory	MSO	Deer Lodge, Flathead, Granite, Lake, Missoula, Powell and 3 more	10 hr
Apr 26, 9:56 AM MDT	Winter Weather Advisory	MSO	Flathead, Lake	32 hr
Apr 26, 11:17 AM MDT	Areal Flood Warning	MSO	Ravalli	47 hr
Apr 26, 11:23 AM MDT	Areal Flood Warning	MSO	Missoula	55 hr
Apr 26, 2:11 PM MDT	Special Weather Statement	MSO	Ravalli	64 min
Apr 26, 3:00 PM MDT	Special Weather Statement	MSO	Ravalli	60 min
Apr 26, 4:15 PM MDT	Special Weather Statement	MSO	Lake, Powell	45 min

Nearby

Areal Flood Warnings in Montana, 2012 Every areal flood warning in 2012

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.