Record rainfall on the 13th of March resulted in several small mud and rock slides near Riverside, WA. The most significant debris flow occurred along Tunk Valley Road.
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Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS OTX wrote it up.
Record rainfall on the 13th of March resulted in several small mud and rock slides near Riverside, WA. The most significant debris flow occurred along Tunk Valley Road. Omak received a record twenty-four hour rainfall of 0.78 the evening of the 13th.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Spokane, WA wrote its last area forecast discussion before the first event at Mar 13, 3:04 PM PST, 4 hours 56 minutes earlier.
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPOKANE WA
404 PM PDT SUN MAR 13 2011
.SYNOPSIS...
A VERY WET STORM WILL CROSS THE INLAND NORTHWEST THIS EVENING AND
RESULT IN MODERATE TO LOCALLY HEAVY PRECIPITATION OVER MUCH OF
THE AREA THROUGH TONIGHT. WHILE MOST OF THE PRECIPITATION WILL
FALL AS RAIN...HEAVY SNOW WILL FALL OVER THE NORTHERN CASCADES.
THE THREAT OF PRECIPITATION WILL DECREASE MONDAY...BUT MORE WET
WEATHER IS EXPECTED THROUGH MOST OF NEXT WEEK.
&&
.DISCUSSION...
TONIGHT...HOURLY PCPN RATES OF 2-4 HUNDREDTHS WILL SPREAD QUICKLY
NE ACROSS ERN WA AND INTO N ID LATE AFTERNOON AND EVENING. TEMPERATURES
HAVE BEEN SLOW TO WARM IN THE CASCADES...NOT MUCH HIGHER THAN THE
MID 30S FOR MOST VALLEY TOWNS...WITH PASSES SUCH AS BLEWETT AND
LOUP LOUP IN THE UPPER 20S TO LOWER 30S. THE WINTER STORM WARNING
FOR ELEVATIONS ABOVE 3000 FT IN THE CASCADES IS STILL ON
TRACK...WITH 5-9 INCHES EXPECTED ABOVE 3000 FT (SLIGHTLY LESS THAN
THE CURRENT WARNING WORDING). FOR CASCADE VALLEYS BELOW 2000 FT
MUCH OF THE SNOW WILL ONLY ACCUMULATE ON GRASSY SURFACES.
ACCUMULATING SNOWS WILL END IN THE CASCADES ONCE THE FLOW VEERS
SUFFICIENTLY TO THE W/SW WITH COLD FROPA AND PRODUCES A
STRENGTHENING PCPN SHADOW. SNOW LEVELS WILL FALL ACROSS N ID
OVERNIGHT...WITH ACCUMULATING SNOWS GENERALLY ABOVE ALL PASS
LEVELS. FOR WINDS...COLD FROPA AND DEEPENING COLD ADVECTION WILL
ACCOMPANY AN INCREASE IN WINDS LATER THIS EVENING...REMAINING
GUSTY MUCH OF THE NIGHT AS THE WIND PROFILE REMAINS NEARLY
UNIDIRECTIONAL W/SW. MARGINAL WIND ADVSY STRENGTH WINDS ARE IN THE
FCST. A WIND ADVSY MAY NEED TO BE ISSUED IN THE EVENING. BZ
MONDAY THROUGH TUESDAY NIGHT...WEATHER ACROSS THE INLAND
NORTHWEST REMAINS ACTIVE AS THE SERIES OF SYSTEMS COMING OFF THE
ASIAN CONTINENT CONTINUE TO ADVANCE IN. THE SYSTEM THAT ENTERS
SUNDAY NIGHT WILL CONTINUE TO MOVE THROUGH MONDAY. THE COLD FRONT
WILL BE EAST OF THE AREA...LEAVING THE REGION UNDER A COOLER AND
MARGINALLY UNSTABLE UPPER TROUGH. A PASSING MID-LEVEL SHORTWAVE
AND WESTERLY FLOW WILL PROVIDE THE BEST LIFT OVER THE CASCADES AND
EASTERN THIRD OF WASHINGTON. MOISTURE REMAINS GOOD TO FAIR WITH
PWATS NEAR 100 PERCENT OF NORMAL. THESE INGREDIENTS TRANSLATE TO A
THREAT OF SHOWERS ACROSS THE AREA. THE HIGHEST PRECIPITATION RISK
WILL BE IN THE AFTERNOON WHEN THE SHORTWAVE PASSES AND INTERACTS
WITH THE BEST INSTABILITY. IN A RELATIVE SENSE HOWEVER THE LOWEST
THREAT WILL BE IN LEE OF THE CASCADES AND DEEPER BASIN. IN
ADDITION LOOK FOR BREEZY/GUSTY WINDS AS THE ATMOSPHERE MIXES INTO
SOME 25-35KT WINDS AROUND 850 MB...BEFORE THEY BEGIN TO WANE LATER
IN THE DAY INTO THE EVENING.
THE PRECIPITATION THREAT BRIEFLY WANES AFTER DARK MONDAY EVENING.
HOWEVER THE NEXT FRONTAL WAVE IS PROJECTED TO START IN OVERNIGHT.
AS A RESULT OF THE LEADING WARM FRONT AND OVERRUNNING MOISTURE
(WITH PWATS RISING TO NEAR 150-200 PERCENT OF NORMAL BY THE
MORNING)...PRECIPITATION CHANCES INCREASE AGAIN FROM THE
WEST...BECOMING LIKELY THROUGHOUT MUCH OF THE AREA TUESDAY. THE
PRECIPITATION THREAT WILL BE FURTHER ENHANCED BY AFTERNOON FROM
THE PALOUSE TO NORTHEAST MOUNTAINS AND PANHANDLE...WITH THE
INCOMING OCCLUDED FRONT AND ANOTHER MID-LEVEL SHORTWAVE. IN
ADDITION LOOK FOR SOME LOCALLY BREEZY CONDITIONS AGAIN. THE THREAT
OF PRECIPITATION WILL REMAIN HIGH INTO TUESDAY NIGHT AS A
SECONDARY FRONT AND MID-LEVEL SHORTWAVE PASS. THE PRIMARY AREA
THAT WILL SEE THE THREAT OF PRECIPITATION BEGINNING TO WANE
TUESDAY NIGHT WILL BE IN THE LEE OF THE CASCADES/DEEPER BASIN AS
THE FRONT AND DEEPER MOISTURE PLUME SHIFTING EAST.
IN THE 24-HOUR PERIOD FROM 12Z TUESDAY TO 12Z WEDNESDAY (5AM-5AM)
MODELS DEPICT AN AVERAGE 0.40 TO 0.75 INCHES OF LIQUID PRECIPITATION
OUTSIDE OF THE DEEPER BASIN/LEE OF THE CASCADES...AND LOCAL
AMOUNTS NEAR AN INCH TO AN INCH AND A HALF IN THE HIGHER
MOUNTAINS. AFTERNOON SNOW LEVELS ARE EXPECTED TO AVERAGE NEAR
3-4KFT OVER THE NORTHERN TWO-THIRDS OF THE CWA AND NEAR 4-5KFT
OVER THE SOUTHERN CWA. HOWEVER TUESDAY MORNING AND THEN LATE
TUESDAY NIGHT INTO WEDNESDAY MORNING SNOW LEVELS WILL BE CLOSER TO
1-2KFT AROUND THE PERIPHERY OF THE CWA...FROM THE CASCADES TO THE
NORTHERN MOUNTAINS. THIS WILL MEAN ACCUMULATIONS IN SOME VALLEYS
NEAR THE MOUNTAINS. WE WILL HAVE TO MONITOR FOR POSSIBLE
HIGHLIGHTS IN MOUNTAINS THEMSELVES (LARGELY THOSE AREAS ABOVE
3KFT) AND MORE SO IN THE CASCADES. VALLEY LOCATIONS WILL BE MORE
MARGINAL. /JCOTE
HYDROLOGY...WITH THE ONSLAUGHT OF SYSTEMS AND ACCOMPANYING
PRECIPITATION SOME RISES ARE PROJECTED FOR AREA WATERWAYS. THE
RIVER FORECAST CENTER IN PORTLAND (WHO MODELS AND FORECASTS SUCH
THINGS FOR MUCH OF THE NORTHWEST U.S.) IS SHOWING RISES ON SOME OF
THE MAIN STEM RIVERS INTO MIDDLE TO LATTER PART OF THE WEEK.
HOWEVER NONE OF THESE ARE CURRENTLY PROJECTED TO RISE ENOUGH TO
CAUSE PROBLEMS. YET WE WILL HAVE TO MONITOR THE SMALL STREAMS/CREEKS
FOR POSSIBLE FLOODING ISSUES (ESPECIALLY NEAR AND AROUND RISING
TERRAIN) AND PONDING OF WATER IN POOR DRAINAGE AREAS. /JCOTE
WEDNESDAY THROUGH SUNDAY...LONGWAVE TROF INFLUENCES THE WEATHER
PATTERN THROUGH THIS TIME INTERVAL WITH JET STREAM POSITIONING
GENERALLY TO THE SOUTH OF EASTERN WASHINGTON AND NORTHERN IDAHO.
THE RESULT IS A CONDITIONALLY UNSTABLE AIRMASS WITH 700-500MB
LAPSE RATES IN THE 7-8 DEG C/KM RANGE A COMMON OCCURRENCE THROUGH
MUCH OF THE TIME INTERVAL DUE TO COLD POOL OF VARYING INTENSITY
PARKED OVERHEAD AS 500MB TEMPS VARY ROUGHLY BETWEEN -34 TO -28.
THE LONGER DAYS OF MARCH TYPICALLY UTILIZE THIS INSTABILITY AND
GENERATE CONVECTIVE SHOWERS WITH SHORTWAVE PASSAGES OR BOUNDARIES
GENERATED DUE TO OROGRAPHIC EFFECTS BECOMING A TRIGGERING
MECHANISM. THE 500MB PATTERN HINTS OF THE POSSIBILITY OF BOTH
MECHANISMS PASSING THROUGH AND POSSIBLY FIRING OFF SHOWERS.
TYPICAL MARCH SNOW LEVELS WHICH ALLOW FOR FROZEN PRECIPITATION TO
REACH THE GROUND AT TIMES BUT WITH VERY SHORT RESIDENCE TIME ON
VALLEY FLOORS DUE TO GROUND AND SURFACE TEMPERATURES EITHER
REMAINING OR RISING ABOVE FREEZING FOR LONGER INTERVALS OF THE
DAY. GRAUPEL MIGHT BE A WORD THAT STARTS TO APPEAR MORE AND MORE
IN THE FORECAST WITH THIS ABOVE SCENARIO AND PERHAPS EVEN THE
OCCASIONAL SIMPLE PULSE THUNDERSTORM THAT THROWS OUT A FEW
LIGHTNING STRIKES AND DECAYS AWAY...ALL IN LESS THAN 30 MINUTES.
GENERAL TROF/COLD POOL IS TYPICAL OF MARCH SO FORECAST
TEMPERATURES REMAIN NEAR NORMAL IN THE FORECAST. /PELATTI
&&
.AVIATION...
RAIN SPREADING FROM WEST TO EAST WITH WET FRONT PASSAGE WILL RESULT
IN PRIMARILY MVFR CEILINGS ASSOCIATED WITH ITS OCCURENCE. COOL AND
CONDITIONALLY UNSTABLE AIRMAS LEFT IN ITS WAKE ALLOWS FOR BOTH RAIN
AND SNOW SHOWERS TYPICAL OF MARCH TO POSSIBLY OCCUR AT LOWLAND AND
VALLEY AVIATION AREA LOCATIONS. WINDS WILL BE GUSTY WITH FRONT
PASSAGE...GENERALLY SOUTHEAST AHEAD OF THE FRONT SHIFTING TO SOUTH
AND SOUTWEST AS THE FRONT EXITS. /PELATTI
&&
.PRELIMINARY POINT TEMPS/POPS...
SPOKANE 38 48 33 48 36 45 / 100 60 30 90 80 60
COEUR D'ALENE 35 46 32 46 35 44 / 100 60 40 90 90 70
PULLMAN 37 47 35 47 35 45 / 100 60 30 90 90 60
LEWISTON 40 55 37 56 40 51 / 60 50 20 70 80 50
COLVILLE 34 48 33 48 36 45 / 100 60 30 100 70 60
SANDPOINT 35 44 32 43 34 42 / 100 80 50 90 100 80
KELLOGG 33 44 30 44 33 42 / 100 90 60 100 100 90
MOSES LAKE 36 54 33 55 36 53 / 100 40 40 80 50 20
WENATCHEE 34 51 33 51 34 50 / 90 40 40 80 40 20
OMAK 34 49 32 49 35 48 / 100 60 40 100 50 20
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...NONE.
WA...WINTER STORM WARNING UNTIL 11 PM PDT THIS EVENING ABOVE 3000
FEET FOR THE EAST SLOPES NORTHERN CASCADES.
&&HAZARDOUS WEATHER OUTLOOK...UPDATED NATIONAL WEATHER SERVICE SPOKANE WA 438 PM PDT SUN MAR 13 2011 IDZ001>004-026-027-WAZ031>038-041-043-044-142345- NORTHERN PANHANDLE-COEUR D'ALENE AREA-IDAHO PALOUSE- CENTRAL PANHANDLE MOUNTAINS-LEWISTON AREA- LEWIS AND SOUTHERN NEZ PERCE COUNTIES-NORTHEAST BLUE MOUNTAINS- LOWER GARFIELD AND ASOTIN COUNTIES-WASHINGTON PALOUSE- MOSES LAKE AREA-UPPER COLUMBIA BASIN-SPOKANE AREA- NORTHEAST MOUNTAINS-OKANOGAN HIGHLANDS-WENATCHEE AREA- OKANOGAN VALLEY-WATERVILLE PLATEAU- 438 PM PDT SUN MAR 13 2011 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTH IDAHO... NORTH CENTRAL IDAHO...CENTRAL WASHINGTON...EAST CENTRAL WASHINGTON...NORTH CENTRAL WASHINGTON...NORTHEAST WASHINGTON AND SOUTHEAST WASHINGTON. .DAY ONE...THIS AFTERNOON AND TONIGHT NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME. .DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME. WAZ042-142345- EAST SLOPES NORTHERN CASCADES- 438 PM PDT SUN MAR 13 2011 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTH CENTRAL WASHINGTON. .DAY ONE...THIS EVENING AND TONIGHT ADDITIONAL SNOW ACCUMULATIONS ABOVE 3000 FEET WILL BE LIKELY UNTIL COLD FRONTAL PASSAGE THIS EVENING...ESPECIALLY ACROSS MOUNTAIN PASSES SUCH AS LOUP LOUP AND BLEWETT. A WINTER STORM WARNING IS IN EFFECT. THE HEAVY SNOW THREAT FOR THE EAST SLOPES OF THE CASCADES WILL END THIS EVENING. .DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.
The national radar mosaic for the moment the first event began.
1 debris flow. Local standard time, as filed.
A landslide blocked Tunk Valley Road for about three hours at the hairpin turn northeast of Riverside. Another small mudslide impacted Riverside-Eastside Road. All roads were cleared by the afternoon of the 14th.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Washington in 2011Every state in 2011This day in weather historyWarnings in Washington, March 2011
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 284752.