A strong winter storm with a significant Pacific moisture tap moved into the Intermountain West spreading heavy, wet snow across parts of Southeast Oregon and Southwest Idaho on the 15th and 16th of December.
Every event with a place to put it; 5 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.
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 BOI wrote it up.
A strong winter storm with a significant Pacific moisture tap moved into the Intermountain West spreading heavy, wet snow across parts of Southeast Oregon and Southwest Idaho on the 15th and 16th of December.
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 Boise, ID wrote its last area forecast discussion before the first event at Dec 14, 8:34 PM MST, 6 hours 26 minutes earlier.
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
834 PM MST MON DEC 14 2009
.DISCUSSION...NEW MODEL RUNS CONFIRM EARLIER THINKING ON WINTER
STORM POISED TO MOVE INTO THE AREA. WINTER STORM CONDITIONS WILL
BEGIN SHORTLY AFTER MIDNIGHT IN NORTHERN HARNEY COUNTY AND IN
BAKER COUNTY OREGON AND SPREAD INTO THE WEST CENTRAL AND BOISE
MOUNTAINS OF IDAHO AROUND DAWN ON TUESDAY. HEAVY SNOW WILL OCCUR
IN THESE AREAS. THE FORECAST FOR THE TREASURE VALLEY IS A LITTLE
MORE UNCERTAIN. SOUTHEAST WINDS HAVE HELPED KEEP TEMPERATURES
ABOVE FREEZING IN BOISE SO FAR THIS EVENING. HOWEVER...EVAPORATIVE
COOLING SHOULD ALLOW TEMPERATURES TO FALL INTO THE UPPER 20S AT
THE ONSET OF PRECIPITATION. SNOW IS EXPECTED TO BEGIN AROUND 7 AM
IN THE TREASURE VALLEY AND CONTINUE INTO THE EARLY AFTERNOON. THE
ONSET OF PRECIPITATION IN THE TREASURE VALLEY IS A LITTLE SLOWER
THAN EARLIER INDICATED BUT STILL EARLY ENOUGH TO AFFECT RUSH HOUR
TRAFFIC. FORECAST TEMPERATURE PROFILES FROM THE 00Z NAM MODEL
CONTINUE TO INDICATE A CHANGE OVER TO RAIN IN THE AFTERNOON IN
BOISE WHICH WILL LIMIT SNOW ACCUMULATIONS IN THE UPPER TREASURE
VALLEY. HOWEVER...COLD AIR WHICH HAS POOLED IN THE LOWER TREASURE
VALLEY IN THE VICINITY OF ONTARIO WILL ALLOW SNOW TO CONTINUE ALL
DAY RESULTING IN HEAVIER ACCUMULATIONS THERE. SNOW CHANGING TO
RAIN IS ALSO LIKELY TOMORROW IN THE MAGIC VALLEY INCLUDING THE
TWIN FALLS AREA. MINOR UPDATES TO WATCHES AND ADVISORIES HAVE BEEN
MADE TO ADJUST TIMING AND SNOW AMOUNTS.
&&
.AVIATION...VFR CONDITIONS WILL CONTINUE ON THE IDAHO SIDE OF THE
BORDER THIS EVENING WITH SCT-BKN DECKS ABOVE 15K FT MSL. CONDITIONS
WILL DETERIORATE ON THE OREGON SIDE WITH MVFR CEILINGS AND
VISIBILITIES IN SNOW AT KBKE AND KBNO BY 06Z-08Z. MOUNTAIN
OBSCURATION WITH AREAS OF MVFR CONDITIONS IN THE VALLEYS...AND LOCAL
IFR/LIFR... WILL SPREAD EAST ACROSS THE WEST CENTRAL IDAHO AND BOISE
MOUNTAINS AFTER 06Z REACHING KBOI BY 12Z AND KTWF/KJER BY 18Z.
SURFACE WINDS WILL BE LIGHT. WINDS ALOFT WILL BE MODERATE WESTERLY.
&&
.PREV DISCUSSION...
SHORT TERM...A LARGE PACIFIC STORM SYSTEM IS POISED TO MOVE INTO
THE AREA. THIS SYSTEM HAS A LONG PLUME OF HIGH PWAT STREAMING FAR TO
THE SOUTHWEST TO JUST NORTH OF HAWAII. UNLIKE THE LAST SYSTEM THIS
WEEKEND...THIS ONE IS AIMED DIRECTLY AT OUR CENTRAL MOUNTAINS AND
AREAS ON THE WEST COAST DUE WEST OF BOISE. STORM HAS WARMER AIR
ENTRAINED INTO IT AND THEREIN LIES THE DIFFICULTY IN THE FORECAST.
WHAT HAPPENS EARLY TONIGHT TEMPERATURE WISE WILL HAVE A BIG EFFECT
ON WHAT TRANSPIRES DURING TUESDAY MORNING WHEN THE FIRST PART OF THE
STORM IS UNDERWAY ACROSS THE AREA. CURRENTLY...MODEL SOUNDINGS
INDICATING AN ALL SNOW EVENT THROUGH MID DAY TUESDAY EVEN FOR THE
TREASURE VALLEY. BY AFTERNOON SNOW LEVELS AND WARMER AIR BEGIN TO
WORK IN PRODUCING A MIXTURE OF SNOW AND RAIN AT LOWER ELEVATIONS BUT
STILL ALL SNOW IN THE MOUNTAINS AND HIGHLANDS. HAVE GONE OUT WITH
MULTIPLE HIGHLIGHTS FOR THIS ONE WITH POSSIBLE CHANGES OR
ADJUSTMENTS ON THE EVENING SHIFT AS THE EVENT NEARS. AT ANY
RATE...THE MOUNTAINS OF BAKER COUNTY...WEST CENTRAL MOUNTAINS AND
OWYHEES LOOK TO GET JUST WHAT SANTA HAS PROMISED...A GOOD DUMPING OF
SNOW EVEN IN THE LOWER ELEVATIONS AND HIGHLANDS OF SOUTHEAST OREGON
AND SOUTHWEST IDAHO...A GOOD AMOUNT OF SNOW IS EXPECTED TO FALL
BEFORE WARMER AIR GETS HERE. THE REAL TRICK IS THE TREASURE VALLEY
WHERE TEMPERATURE PROFILES OVERNIGHT ARE CRITICAL TO WHAT TYPE
PRECIP AND HOW MUCH QPF FALLS. SEE SPECIFIC WSWBOI PRODUCTS FOR
DETAILS ON SNOW AMOUNTS AND TIMING.
LONG TERM...WEDNESDAY NIGHT THROUGH MONDAY...A WEAK SHORTWAVE WILL
TRANSITION ACROSS NORTH IDAHO EARLY THURSDAY - CONTINUING CHANCES
FOR PRECIPITATION ACROSS NORTHERN TERRAIN. ON FRIDAY...MODELS AGREE
UPON AN AMPLIFIED UPPER RIDGE OVER THE PAC NW BUT LOCATION OF RIDGE
AXIS REMAINS UNCERTAIN. THIS PROVES PROBLEMATIC IN FORECASTING THE
LOCATION /AND THUS TIMING/ OF THE NEXT PACIFIC SYSTEM. FOR
NOW...HAVE MAINTAINED SLIGHT CHANCE TO CHANCE POPS ACROSS SE OREGON
AND HIGHER TERRAIN OF SW ID ON FRIDAY/SATURDAY. ID VALLEYS MORE
LIKELY TO REMAIN DRY AND STABLE AND HAVE MINIMIZED POPS EAST OF
BOISE. BY SUNDAY...CONFIDENCE DECREASES AS ECMWF MAINTAINS WRN CONUS
RIDGE AND GFS DIGS PACIFIC TROUGH INLAND. THEREFORE...HAVE TRENDED
SUNDAY/MONDAY TEMPERATURES AND POPS TOWARD CLIMO.
AVIATION...PREDOMINANTLY VFR THROUGH 00Z WITH SCT-BKN CLOUD DECKS
AROUND 10K TO 12K FT MSL. LIGHT SURFACE WINDS WITH MODERATE WESTERLY
WINDS ALOFT. THIS EVENING...CEILINGS WILL THICKEN AND LOWER /FROM
THE NW/ IN ADVANCE OF THE NEXT STORM SYSTEM. EXPECT WIDESPREAD IFR
IN SNOW AND FOG...MOUNTAIN OBSCURATION...AND GUSTY SE-SW SURFACE
WINDS AFTER 04Z /9 PM MST/ TONIGHT.
&&
.BOI WATCHES/WARNINGS/ADVISORIES...
ID...WINTER STORM WARNING FROM 5 AM TO 5 PM MST TUESDAY FOR IDZ011-
IDZ013-IDZ029-IDZ033.
WINTER WEATHER ADVISORY FROM 5 AM TO 2 PM MST TUESDAY FOR IDZ012-
IDZ014-IDZ015-IDZ016-IDZ028-IDZ030.
OR...WINTER WEATHER ADVISORY FROM 5 AM MST /4 AM PST/ TO 2 PM MST /1
PM PST/ TUESDAY FOR ORZ063.
WINTER STORM WARNING FROM 5 AM TO 2 PM MST TUESDAY FOR ORZ064.
WINTER STORM WARNING FROM 10 PM THIS EVENING TO 4 PM PST TUESDAY
FOR ORZ061-ORZ062.
&&
WEATHER.GOV/BOISE
DISCUSSION...JB
AVIATION.....JT
PREV SHORT TERM...GS
PREV LONG TERM....MT/JSHAZARDOUS WEATHER OUTLOOK...UPDATED NATIONAL WEATHER SERVICE BOISE ID 209 PM MST MON DEC 14 2009 IDZ012-014-016-028-151200- LOWER TREASURE VALLEY ID-UPPER TREASURE VALLEY- WESTERN MAGIC VALLEY-CAMAS PRAIRIE- 209 PM MST MON DEC 14 2009 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTH CENTRAL IDAHO AND SOUTHWEST IDAHO. .DAY ONE...THIS AFTERNOON AND TONIGHT NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME. .DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY A WINTER WEATHER ADVISORY IN EFFECT FROM 5 AM MST /4 AM PST/ TO 2 PM MST /1 PM PST/ TUESDAY FOR THE UPPER AND LOWER TREASURE VALLEY OF IDAHO...WESTERN MAGIC VALLEY AND CAMAS PRAIRIE FOR MODERATE SNOW. 2 TO 5 INCHES OF SNOW WITH UPWARDS OF 4 TO 7 INCHES IN THE CAMAS PRAIRIE. THE AREA AROUND BOISE MAY SEE ONLY ABOUT TWO INCHES. FOR THE LATEST UPDATES...LISTEN TO NOAA WEATHER RADIO OR CHECK ONLINE AT WWW.WEATHER.GOV. .SPOTTER INFORMATION STATEMENT... SPOTTERS SHOULD REPORT SIGNIFICANT WEATHER IN ACCORDANCE WITH ESTABLISHED PROCEDURES. IDZ011-013-029-151200- WEST CENTRAL MOUNTAINS-BOISE MOUNTAINS-OWYHEE MOUNTAINS- 209 PM MST MON DEC 14 2009 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTHWEST IDAHO AND WEST CENTRAL IDAHO. .DAY ONE...THIS AFTERNOON AND TONIGHT NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME. .DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY A WINTER STORM WARNING IN EFFECT FROM 5 AM TO 5 PM MST TUESDAY FOR HEAVY SNOW IN THE WEST CENTRAL AND BOISE MOUNTAINS AND THE OWYHEE MOUNTAINS. 5 TO 8 INCHES IN THE VALLEYS WITH 8 TO 14 INCHES IN THE MOUNTAINS IS EXPECTED. FOR THE LATEST UPDATES...LISTEN TO NOAA WEATHER RADIO OR CHECK ONLINE AT WWW.WEATHER.GOV. .SPOTTER INFORMATION STATEMENT... SPOTTERS SHOULD REPORT SIGNIFICANT WEATHER IN ACCORDANCE WITH ESTABLISHED PROCEDURES. IDZ015-030-ORZ063-151200- SOUTHWEST HIGHLANDS-SOUTHERN TWIN FALLS COUNTY-MALHEUR COUNTY- 209 PM MST MON DEC 14 2009 /109 PM PST MON DEC 14 2009/ THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTH CENTRAL IDAHO...SOUTHWEST IDAHO AND SOUTHEAST OREGON. .DAY ONE...THIS AFTERNOON AND TONIGHT NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME. .DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY A WINTER WEATHER ADVISORY FOR MODERATE SNOW IS IN EFFECT FROM 5 AM MST /4 AM PST/ TO 2 PM MST /1 PM PST/ TUESDAY FOR SOUTHWEST HIGHLANDS...SOUTHERN TWIN FALLS COUNTY AND MALHEUR COUNTY. 2 TO 5 INCHES OF SNOW WITH UPWARDS OF 4 TO 7 INCHES. FOR THE LATEST UPDATES...LISTEN TO NOAA WEATHER RADIO OR CHECK ONLINE AT WWW.WEATHER.GOV. .SPOTTER INFORMATION STATEMENT... SPOTTERS SHOULD REPORT SIGNIFICANT WEATHER IN ACCORDANCE WITH ESTABLISHED PROCEDURES. IDZ033-ORZ064-151200- UPPER WEISER RIVER-LOWER TREASURE VALLEY OR- 209 PM MST MON DEC 14 2009 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF WEST CENTRAL IDAHO AND SOUTHEAST OREGON. .DAY ONE...THIS AFTERNOON AND TONIGHT NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME. .DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY WINTER STORM WARNING FOR HEAVY SNOW IN EFFECT FROM 5 AM TO 5 PM MST TUESDAY FOR THE UPPER WEISER RIVER AND IN EFFECT FOR THE LOWER TREASURE VALLEY OF OREGON TO 2 PM MST. 5 TO 7 INCHES OF SNOW IS EXPECTED IN THE UPPER WEISER RIVER WITH UP TO 4 INCHES OF SNOW EXPECTED IN THE LOWER TREASURE VALLEY. FOR THE LATEST UPDATES...LISTEN TO NOAA WEATHER RADIO OR CHECK ONLINE AT WWW.WEATHER.GOV. .SPOTTER INFORMATION STATEMENT... SPOTTERS SHOULD REPORT SIGNIFICANT WEATHER IN ACCORDANCE WITH ESTABLISHED PROCEDURES. ORZ061-062-151200- HARNEY COUNTY-BAKER COUNTY- 109 PM PST MON DEC 14 2009 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTHEAST OREGON AND SOUTHEAST OREGON. .DAY ONE...THIS AFTERNOON AND TONIGHT A WINTER STORM WARNING FOR HEAVY SNOW IN BAKER COUNTY AND HARNEY COUNTY OREGON IS IN EFFECT FROM 10 PM PST THIS EVENING TO 4 PM PST TUESDAY. 3 TO 5 INCHES IN THE BAKER VALLEY WITH 8 TO 14 INCHES IN THE BLUES AND WALLOWA MOUNTAINS. 2 TO 5 INCHES OF SNOW IN THE HIGHLANDS WITH 6 TO 10 INCHES IN THE STEENS AND 8 TO 12 INCHES IN THE SOUTHERN BLUES OF NORTHERN HARNEY COUNTY. FOR THE LATEST UPDATES...LISTEN TO NOAA WEATHER RADIO OR CHECK ONLINE AT WWW.WEATHER.GOV. .DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY A WINTER STORM WARNING CONTINUES FOR HEAVY SNOW IN BAKER COUNTY AND HARNEY COUNTY OREGON TO 4 PM PST TUESDAY. FOR THE LATEST UPDATES...LISTEN TO NOAA WEATHER RADIO OR CHECK ONLINE AT WWW.WEATHER.GOV. .SPOTTER INFORMATION STATEMENT... SPOTTERS SHOULD REPORT SIGNIFICANT WEATHER IN ACCORDANCE WITH ESTABLISHED PROCEDURES.
The national radar mosaic for the moment the first event began.
4 heavy snow, 1 avalanche. Local standard time, as filed.
Trained spotters and cooperative observers near Midvale, Cambridge and Council, Idaho reported from 5 to 12 inches of snow.
Trained spotters and cooperative observers in Boise and Elmore counties reported from 7 to 13 inches of snow. Most of the heavy snowfall occured during the day on the 15th.
Trained spotters near Payette reported from 4 to 8 inches of snow.
Trained spotters and cooperative observers around the McCall and New Meadows areas reported 6 to 8 inches of snow and locally 12 inches in southwest Adams County.
Idaho Mountain Express reported that a young man died in an avalanche while snowmobiling at Rock Lake in the French Creek drainage outside of Cascade, Idaho.
As the offices recorded each death: direct deaths were caused by the weather itself, indirect ones by something it set in motion.
| Event | Date | Age | Sex | Where | Kind |
|---|---|---|---|---|---|
| Avalanche, West Central Mountains | 2009-12-17 | Male | Outside/Open Areas | Direct |
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Idaho in 2009Every state in 2009This day in weather historyWarnings in Idaho, December 2009
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: 206479, 206475, 206484, 206471, 206493.