NORTHWEST RIVER FORECAST CENTER PORTLAND OR
PRECIPITATION, TEMPERATURE, SNOW, AND STREAMFLOW SUMMARIES
JAN 12
WEATHER SUMMARY
JANUARY STARTED OUT FAIRLY TRANQUIL AS THE JET STREAM KEPT THE MAIN STORM TRACK
NORTH OVER BRITISH COLUMBIA. MOST OF THE REGION SAW DRY WEATHER THROUGH THE
FIRST 10 DAYS OF THE MONTH...WITH A COUPLE EXCEPTIONS AS WEAK COLD FRONTS
MOVED THROUGH. THROUGH THE END OF THE SECOND WEEK...HIGH PRESSURE BUILT OVER
THE REGION BRINGING CONTINUED DRY AND WARM WEATHER EXCEPT THROUGH MOUNTAIN
VALLEYS WHERE INVERSIONS SET UP.
THE WEATHER PATTERN CHANGED DURING THE THIRD WEEK OF THE MONTH AND A SERIES OF
STRONG STORMS MADE THEIR WAY ONSHORE. THESE SYSTEMS BROUGHT QUITE A BIT OF
PRECIPITATION AND HIGH WATER TO BASINS WEST OF THE CASCADE CREST...AND
WIDESPREAD SNOW COVER THE AREAS EAST. STORMY WEATHER CONTINUED INTO THE FORTH
WEEK OF THE MONTH. TOWARDS THE END OF THE LAST WEEK...THE STORM TRACK SHIFTED
NORTH AGAIN BRINGING ADDITIONAL PRECIPITATION AMOUNTS TO B.C. AND KEEPING MOST
OF THE REST OF THE BASIN DRY THROUGH THE END OF THE JANUARY.
PRECIPITATION SUMMARY
JANUARY PRECIPITATION WAS: 117 PERCENT OF NORMAL (1971-2000) AT COLUMBIA ABOVE
COULEE, 119 PERCENT OF NORMAL AT THE SNAKE RIVER ABOVE ICE HARBOR, AND 122
PERCENT OF NORMAL AT COLUMBIA ABOVE THE DALLES.
SEASONAL (OCTOBER THROUGH JANUARY) PRECIPITATION WAS: 93 PERCENT OF NORMAL
(1971-2000) AT COLUMBIA ABOVE COULEE, 95 PERCENT OF NORMAL AT THE SNAKE RIVER
ABOVE ICE HARBOR, AND 95 PERCENT OF NORMAL AT COLUMBIA ABOVE THE DALLES.
TEMPERATURE SUMMARY
THE 37 STATION TEMPERATURE INDEX FOR THE PACIFIC NORTHWEST DEPARTED
+1.9 DEGREES FROM NORMAL RELATIVE TO THE 1971-2000 NORMALS. MEAN
TEMPERATURE DEPARTURES RANGED FROM -3.5 TO 9.4 DEGREES.
GENERAL SUMMARY
ABOVE AVERAGE JANUARY PRECIPITATION ALONG WITH SOME IMPROVEMENT IN SNOW WATER
EQUIVALENTS (SWE'S) HAVE PRODUCED AN IMPROVEMENT TO THE EXPECTED STREAMFLOW
FORECASTS. MONTHLY PRECIPITATION RANGED FROM 100 TO 150 PERCENT OF AVERAGE
OVER THE COLUMBIA SNAKE BASIN. SWE VALUES IMPROVED TO GENERALLY IN THE 80 TO
100 PERCENT RANGE. AS A RESULT THE JANUARY THROUGH JULY FORECAST FOR THE
COLUMBIA RIVER AT THE DALLES IS AT 85 PERCENT OF THE 30 YEAR AVERAGE.
SNOW SUMMARY
FEBRUARY 1ST SWE'S RANGED FROM 125 PERCENT IN PARTS OF THE UPPER COLUMBIA BASIN
TO 80 PERCENT IN NE OREGON. THE AREA ABOVE GRAND COULEE DAM HAS FEBRUARY 1ST
SWE VALUES IN THE 90 TO 125 PERCENT RANGE. THE SNAKE BASIN REPORTS SWE IN THE 85
TO 90 PERCENT RANGE. WEST OF THE CASCADES SWE VALUES RANGE FROM 100 PERCENT IN NW
WASHINGTON TO 60 PERCENT IN WESTERN OREGON.
STREAMFLOW SUMMARY
STREAMFLOW DURING JANUARY WAS QUITE VARIABLE. THE CLARK FORK AREA IN MONTANA
AND THE UPPER SNAKE AREA HAD STREAMFLOW IN THE 100 TO 120 PERCENT RANGE. THE
LOWEST MONTHLY STREAMFLOW WAS OBSERVED ON THE SPOKANE RIVER...THE LOWER SNAKE
AREA RIVERS AND ON THE YAKIMA RIVER AT 40 TO 70 PERCENT OF AVERAGE. MONTHLY
STREAMFLOW AT THE DALLES WAS 80 PERCENT OF THE 30 YEAR AVERAGE. WEST OF THE
CASCADES RAIN EVENTS PRODUCED HIGH STREAMFLOW RANGING FROM NEAR AVERAGE IN
WESTERN WASHINGTON TO 140 TO 150 PERCENT IN WESTERN OREGON.
HEAVY RAIN DURING THE LAST HALF OF JANUARY PRODUCED FLOODING FROM THE OLYMPIC
BASINS IN WASHINGTON TO THE COQUILLE BASIN IN SW OREGON. THE MOST SERIOUS
FLOODING HAPPENED IN THE CENTRAL WILLAMETTE VALLEY WHERE 8 TO 12 INCHES OF
RAIN FELL IN A TWO DAY PERIOD. THE MARY'S RIVER NEAR PHILOMATH HAD A RECORD
PEAK AT 21.5 FEET. ALSO SMALL STREAMS IN THE CENTRAL WILLAMETTE VALLEY
SUCH AS MILL CREEK CAUSED SERIOUS LOCAL FLOOD PROBLEMS. THE WILLAMETTE RIVER
AT SALEM CRESTED AT 29.4 FEET ON JANUARY 21ST 1.4 FEET OVER FLOOD STAGE.
ABOVE AVERAGE PRECIPITATION DURING JANUARY COUPLED WITH AN IMPROVEMENT IN SNOW
WATER EQUIVALENTS BROUGHT AN INCREASE IN EXPECTED SEASONAL STREAMFLOWS. FEB
1ST STREAMFLOW FORECASTS RANGE FROM 90 TO 110 PERCENT IN THE UPPER COLUMBIA IN
CANADA ON THE CLARK FORK DRAINAGE IN MONTANA AND IN THE UPPER SNAKE BASINS.
LOWEST FEBRUARY 1ST FORECAST STREAMFLOW IS EXPECTED IN THE MIDDLE SNAKE AREA
AND IN EASTERN OREGON AT 50 TO 70 PERCENT OF THE 30 YEAR AVERAGE. THE
FEBRUARY 1ST FORECAST FOR THE COLUMBIA RIVER AT THE DALLES IS 85 PERCENT OF
AVERAGE UP 5 PERCENT FROM JANUARY 1ST.
SEE HTTP://WWW.NWRFC.NOAA.GOV WEB PAGE FOR DETAILED STREAMFLOW FORECASTS.
MONTHLY PRECIPITATION AND TEMPERATURE RECORDS
PARTIAL LIST OF RECORD HIGH AND LOW TEMPERATURES IN DEGREES (F) ARE LISTED BELOW.
PRECIPITATION IS REPORTED IN INCHES.
PLEASE SEE THE COMPLETE LIST OF RECORDS AT THE NATIONAL WEATHER SERVICE FIELD
OFFICES CLIMATOLOGY WEB PAGES.
01/14 RECORD HIGH TEMPERATURE OF 43 DEGREES WAS SET AT IDAHO FALLS ID.
RECORD HIGH TEMPERATURE OF 52 DEGREES WAS SET AT POCATELLO ID.
01/15 RECORD HIGH TEMPERATURE OF 45 DEGREES WAS SET AT IDAHO FALLS ID.
01/17 RECORD PRECIPITATION OF 1.34 INCHES WAS SET AT MULLAN PASS ID.
01/18 RECORD SNOWFALL OF 6.7 INCHES WAS REPORTED AT MULLAN ID.
RECORD SNOWFALL OF 5.3 INCHES WAS REPORTED AT WENATCHEE WA.
RECORD SNOWFALL OF 6.8 INCHES WAS SET AT SEATAC WA.
RECORD SNOWFALL OF 11.0 INCHES WAS SET AT OLYMPIA WA.
RECORD SNOWFALL OF 6.0 INCHES WAS REPORTED AT RITZVILLE WA.
RECORD SNOWFALL OF 8.4 INCHES WAS REPORTED AT LEWISTON ID.
RECORD SNOWFALL OF 6.0 INCHES WAS REPORTED AT SPOKANE WA.
RECORD SNOWFALL OF 5.0 INCHES WAS REPORTED AT GRAND COULEE DAM WA.
RECORD SNOWFALL OF 8.6 INCHES WAS SET AT MISSOULA MT.
01/19 RECORD PRECIPITATION OF 0.39 INCHES WAS REPORTED AT YAKIMA WA.
RECORD SNOWFALL OF 5.0 INCHES WAS SET AT MISSOULA MT.
RECORD SNOWFALL OF 5.0 INCHES WAS REPORTED AT PULLMAN WA.
RECORD RAINFALL OF 0.69 INCHES WAS SET AT POCATELLO ID.
RECORD RAINFALL OF 1.76 INCHES WAS SET AT MCMINNVILLE OR.
01/21 RECORD RAINFALL OF 0.52 INCHES WAS SET AT POCATELLO ID.
01/22 RECORD SNOWFALL OF 4.2 INCHES WAS REPORTED AT YAKIMA WA.
01/24 RECORD RAINFALL OF 1.46 INCH(ES) WAS SET AT EUGENE OR.
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