Water Supply Precipitation Summary

Weekly Divisional Precipitation Summary

Click on date to display a different weekly forecast:

04/28/2009 04/22/2009 04/14/2009 03/31/2009 03/24/2009 03/17/2009 03/11/2009 02/24/2009 02/19/2009 02/10/2009 01/27/2009 01/20/2009 01/13/2009 12/31/2008 12/24/2008 12/16/2008 12/09/2008 11/25/2008 11/18/2008 11/12/2008 10/28/2008 10/21/2008 10/14/2008 10/07/2008 09/23/2008 09/16/2008 09/09/2008 08/26/2008 08/19/2008 08/12/2008 07/29/2008 07/22/2008 07/15/2008 06/24/2008 06/17/2008 06/10/2008 05/27/2008 05/20/2008 05/13/2008 04/29/2008 04/22/2008 04/15/2008 04/08/2008 03/25/2008 03/18/2008 03/12/2008 03/11/2008 02/26/2008 02/20/2008 02/19/2008 02/13/2008 02/12/2008 01/30/2008 01/29/2008 01/23/2008 01/22/2008 01/16/2008 01/08/2008 12/26/2007 12/18/2007 12/11/2007 11/27/2007 11/20/2007 11/13/2007 10/23/2007 10/16/2007 10/09/2007 09/25/2007 09/21/2007 09/11/2007 08/28/2007 08/21/2007 08/14/2007 07/24/2007 07/18/2007 07/17/2007 07/10/2007 06/26/2007 06/19/2007 06/12/2007 05/29/2007 05/23/2007 05/15/2007 05/08/2007 04/24/2007 04/17/2007 04/10/2007 03/27/2007 03/20/2007 03/13/2007 02/27/2007 02/20/2007 02/13/2007 01/23/2007 01/16/2007 01/09/2007 12/26/2006 12/19/2006 12/12/2006 11/28/2006 11/21/2006 11/14/2006 11/07/2006 10/24/2006 10/17/2006 10/12/2006 09/26/2006 09/19/2006 09/12/2006 08/29/2006 08/22/2006 08/16/2006 08/09/2006 07/25/2006 07/18/2006 07/11/2006 06/27/2006 06/20/2006 06/13/2006 05/30/2006 05/23/2006 05/16/2006 05/09/2006 04/18/2006 04/11/2006 03/28/2006 03/21/2006 03/14/2006 03/07/2006 02/21/2006 02/14/2006 02/08/2006 01/24/2006 12/13/2005 12/06/2005 11/29/2005 11/28/2005 11/22/2005 11/15/2005 08/09/2005 07/26/2005 07/19/2005 07/12/2005 06/14/2005 06/07/2005 05/24/2005 05/17/2005 05/11/2005 04/26/2005 04/19/2005 04/12/2005 03/29/2005 03/22/2005 03/15/2005 03/09/2005 02/23/2005 02/15/2005 02/08/2005 01/26/2005 01/19/2005 01/12/2005 12/28/2004 12/22/2004 12/16/2004 12/15/2004 12/08/2004 11/24/2004 11/17/2004 11/09/2004 10/27/2004 10/20/2004 10/13/2004 09/28/2004 09/21/2004 09/15/2004 09/08/2004 08/24/2004 08/17/2004 08/10/2004 07/27/2004 07/20/2004 07/15/2004 07/13/2004 06/29/2004 06/22/2004

 Columbia Basin Seasonal Precipitation Division Averages  
 Northwest River Forecast Center 


 (Weekly Summary: 12Z apr 1 - 27, 2009) 

  DIVISION               ..APR TO DAY 27..   ....OCT - APR.... 
                          OBSD  DEP  PCT AV    OBSD   DEP  PCT AV 

 COLUMBIA ABOVE COULEE   1.16  -0.33  78.    14.80  -0.94  94. 
 SNAKE RV AB ICE HARBOR  1.25  -0.06  95.    12.07   0.46 104. 
 COLUMBIA AB THE DALLES  1.35  -0.13  91.    15.49  -0.28  98. 
 COLUMBIA AB CASTLEGAR   1.57  -0.23  87.    20.03  -2.15  90. 
 KOOTENAI                1.29  -0.29  82.    14.40  -1.76  89. 
 CLARK FORK              0.65  -0.46  58.    11.31   1.20 112. 
 FLATHEAD                1.07  -0.35  75.    12.92  -0.68  95. 
 PEND OREILLE/ SPOKANE   1.50  -0.53  74.    20.62  -1.61  93. 
 NORTHEAST WASHINGTON    0.92  -0.45  67.    10.44  -1.75  86. 
 OKANOGAN                0.66  -0.27  71.     8.50  -1.39  86. 
 EAST SLOPES WASH CASC.  1.50  -0.41  79.    29.78  -3.74  89. 
 CENTRAL WASHINGTON      0.33  -0.25  57.     5.60  -0.89  86. 
 UPPER SNAKE             2.19   0.75 152.    15.08   2.30 118. 
 SNAKE RIVER PLAIN       0.96   0.03 103.     6.65  -0.40  94. 
 OWYHEE/ MALHEUR         0.76  -0.11  87.     7.12  -0.30  96. 
 SALMON/ BOISE/ PAYETTE  0.95  -0.49  66.    12.46  -1.75  88. 
 BURNT/ GRANDE RONDE     0.86  -0.36  70.    10.86   0.02 100. 
 CLEARWATER              1.42  -0.97  59.    23.14   2.14 110. 
 SOUTHEAST WASHINGTON    0.96  -0.54  64.    14.22   0.23 102. 
 UPPER JOHN DAY          1.12  -0.01  99.     9.21  -0.60  94. 
 UMATILLA/ LWR JOHN DAY  1.21  -0.14  89.    12.66   0.96 108. 
 UPR DESCHUTES/ CROOKED  0.77  -0.11  88.    10.21  -0.62  94. 
 HOOD/ LOWER DESCHUTES   1.94   0.01 100.    26.16   2.71 112. 
 NW SLOPE WASH CASCADES  5.70   0.10 102.    62.79  -8.27  88. 
 SW WA CASCADES/COWLITZ  3.90  -0.91  81.    50.82  -7.47  87. 
 WILLAMETTE VALLEY       3.20  -1.15  74.    40.52  -9.10  82. 
 ROGUE/ UMPQUA           1.13  -1.37  45.    25.11  -5.22  83. 
 KLAMATH BASIN           0.73  -0.39  65.    12.37  -2.39  84. 
 LAKE COUNTY-GOOSE LAKE  0.79  -0.26  75.     6.37  -2.33  73. 
 HARNEY/ MALHEUR BASIN   0.70  -0.26  73.     6.25  -1.37  82. 

 This precipitation summary for the Columbia River Basin is based on an 
 analysis using a limited number of reporting stations. Final values 
 depicted in this narrative are prorated by the number of elapsed days  
 in the month. 

 Precipitation normals are based on 1971-2000 historical data. 

 Please contact NWRFC for further information: (503) 326-7291. 
    

Monthly Divisional Precipitation Summary

Click on date to display forecast:

4/2009 3/2009 2/2009 1/2009 1/2009 12/2008 11/2008 10/2008 9/2008 8/2008 7/2008 6/2008 5/2008 4/2008 3/2008 2/2008 1/2008 1/2008 12/2007 11/2007 10/2007 9/2007 8/2007 7/2007 6/2007 5/2007 4/2007 3/2007 2/2007 2/2007 1/2007 12/2006 11/2006 10/2006 9/2006 8/2006 7/2006 6/2006 5/2006 4/2006 3/2006 2/2006 1/2006 11/2005 7/2005 6/2005 5/2005 4/2005 3/2005 2/2005 1/2005 12/2004 11/2004 10/2004 9/2004 8/2004 7/2004 6/2004 13/0606

 Columbia Basin Seasonal Precipitation Division Averages  
 Northwest River Forecast Center 


 (Monthly Summary - apr 2009) 


  DIVISION               ..APR TO DAY 30..   ....OCT - APR.... 
                          OBSD  DEP  PCT AV    OBSD   DEP  PCT AV 

 COLUMBIA ABOVE COULEE   1.00  -0.65  61.    14.65  -1.25  92. 
 SNAKE RV AB ICE HARBOR  1.46   0.00 100.    12.28   0.53 104. 
 COLUMBIA AB THE DALLES  1.41  -0.23  86.    15.55  -0.38  98. 
 COLUMBIA AB CASTLEGAR   1.14  -0.86  57.    19.60  -2.78  88. 
 KOOTENAI                0.99  -0.76  57.    14.11  -2.23  86. 
 CLARK FORK              0.68  -0.56  55.    11.34   1.11 111. 
 FLATHEAD                1.03  -0.55  65.    12.88  -0.88  94. 
 PEND OREILLE/ SPOKANE   1.77  -0.49  78.    20.88  -1.57  93. 
 NORTHEAST WASHINGTON    1.02  -0.50  67.    10.55  -1.79  85. 
 OKANOGAN                0.67  -0.36  65.     8.52  -1.48  85. 
 EAST SLOPES WASH CASC.  1.63  -0.49  77.    29.91  -3.82  89. 
 CENTRAL WASHINGTON      0.45  -0.19  71.     5.73  -0.82  87. 
 UPPER SNAKE             2.42   0.82 151.    15.30   2.36 118. 
 SNAKE RIVER PLAIN       1.12   0.08 108.     6.81  -0.34  95. 
 OWYHEE/ MALHEUR         0.90  -0.07  93.     7.26  -0.26  97. 
 SALMON/ BOISE/ PAYETTE  1.06  -0.54  67.    12.58  -1.79  88. 
 BURNT/ GRANDE RONDE     1.10  -0.26  81.    11.09   0.12 101. 
 CLEARWATER              2.06  -0.60  77.    23.78   2.51 112. 
 SOUTHEAST WASHINGTON    1.43  -0.24  85.    14.68   0.53 104. 
 UPPER JOHN DAY          1.19  -0.06  96.     9.29  -0.65  93. 
 UMATILLA/ LWR JOHN DAY  1.47  -0.03  98.    12.93   1.08 109. 
 UPR DESCHUTES/ CROOKED  0.93  -0.05  95.    10.37  -0.56  95. 
 HOOD/ LOWER DESCHUTES   2.82   0.67 131.    27.04   3.37 114. 
 NW SLOPE WASH CASCADES  6.26   0.04 101.    63.35  -8.33  88. 
 SW WA CASCADES/COWLITZ  5.01  -0.34  94.    51.93  -6.89  88. 
 WILLAMETTE VALLEY       4.08  -0.76  84.    41.40  -8.71  83. 
 ROGUE/ UMPQUA           1.55  -1.23  56.    25.53  -5.07  83. 
 KLAMATH BASIN           0.88  -0.36  71.    12.52  -2.37  84. 
 LAKE COUNTY-GOOSE LAKE  0.87  -0.30  74.     6.44  -2.37  73. 
 HARNEY/ MALHEUR BASIN   0.85  -0.21  80.     6.41  -1.32  83. 

 Columbia River Basin division values are computed by utilizing 
 un-weighted precipitation amounts from key stations in each area. 

 Precipitation normals are based on 1971-2000 historical data. 

 Please contact NWRFC for further information: (503) 326-7291. 
    
NORTHWEST RIVER FORECAST CENTER PORTLAND OR
 
PRECIPITATION, TEMPERATURE, SNOW, AND STREAMFLOW SUMMARIES
 
apr 09 
 

 
WEATHER SUMMARY 
 

 
MOSTLY BENIGN WEATHER WAS EXPERIENCED OVER THE NORTHWEST FOR THE FIRST WEEK OF
 
APRIL. THIS CHANGED BY THE SECOND WEEK AS A STRONG LOW PRESSURE TROUGH INFLUENCED
 
THE REGION THROUGH MID MONTH. HIGH PRESSURE BUILT IN AGAIN BY THE THIRD
 
WEEK...BRINGING IMPROVING WEATHER AND WARM TEMPERATURES. A COLD AIRMASS INTRUDED AT
 
THE BEGINNING OF THE LAST WEEK...BRINGING UNSEASONABLY COLD TEMPERATURES AND
 
UNSETTLED WEATHER. UNSETTLED WEATHER CONTINUED THROUGH THE END OF THE MONTH.
 

 
PRECIPITATION SUMMARY 
 

 
April precipitation was: 61 percent of normal (1971-2000) at Columbia above
 
Coulee, 100 percent of normal at the Snake River above Ice Harbor, and 86 
 
percent of normal at Columbia above the Dalles.
 

 
Seasonal (October through April) precipitation was: 92 percent of normal
 
(1971-2000) at Columbia above Coulee, 104 percent of normal at the Snake River
 
above Ice Harbor, and 98 percent of normal at Columbia above the Dalles.
 

 
TEMPERATURE SUMMARY
 
 
 
The 37 station temperature index for the Pacific Northwest departed
 
-0.9 degrees from normal relative to the 1971-2000 normals.  Mean
 
temperature departures ranged from 0.0 to 2.0 degrees.
 

 
General Summary !
 

 
For the most part forecast streamflows are showing little change from the 
 
April 1st values.  During the month of April lower to mid elevation snow
 
water equivalents (SWE's) have decreased while high elevation sites have   
 
remained the same or increased slightly.  Precipitation for April was
 
slightly below average except in the Upper Snake area where precipitation
 
was above average.  
 

 
Snow Summary !
 

 
Low to mid elevation SWE's have decreased during April while high elevation  
 
sites have remained steady or increased slightly, especially is Western
 
Montana.  May 1st SWE's are 70 to 90 percent of the May 1st average in the
 
Upper Columbia, Kootenai and Flathead river areas.  Most SWE's in the Middle 
 
and Lower Snake area and in the Mid-Columbia tributaries fall in the 80 to 95
 
percent range.  The best May 1st SWE's are in the Clark Fork and Bitterroot
 
drainages in Montana and in the Upper Snake area at 100 to 110 percent.  The
 
lowest SWE's are in the North Cascades in Washington and in Southeast Oregon
 
at 60 to 70 percent.  Snow water equivalent values are above the May 1st
 
average in the Willamette and Southwest Oregon areas.
 

 
Streamflow Summary !
 

 
April streamflow was slightly below average for most of the Columbia-Snake
 
basin.  Lowest April streamflow was 50 to 60 percent on the Upper Columbia
 
and Kootenai rivers and 50 to 70 percent of average in Southeast Oregon. 
 
The highest streamflow during April was in a path from the Blue Mountains
 
in Northeast Oregon to the Clark Fork area in Montana at 110 to 180 percent.
 

 
Slightly below average April precipitation and May 1st snow SWE's in the 
 
major water producing areas of the Columbia staying steady or increasing
 
slightly have produced little change in streamflow forecasts from April
 
1st.  Highest streamflow forecasts are on Blue Mountain tributaries in
 
Northeast Oregon, on the Clearwater river in Idaho and on the Clark Fork
 
river in Western Montana at 100 to 110 percent.  Lowest expected flows
 
are expected in Southeast Oregon at 60 to 70 percent.
 

 
http://www.nwrfc.noaa.gov/water_supply/ws_fcst.cgi
 
has detailed water supply 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.
 
  
 
4/08	A RECORD RAINFALL OF 2.08 INCHES WAS SET AT JEROME ID. 
 
	A RECORD RAINFALL OF 0.39 INCHES WAS SET AT STANLEY ID.
 

 
4/12	A RECORD RAINFALL OF 0.83 INCHES WAS SET AT SEATTLE-TACOMA AIRPORT WA.
 
 	A RECORD RAINFALL OF 1.02 INCHES WAS SET AT OLYMPIA WA.
 

 
4/20 	A RECORD HIGH TEMPERATURE OF 74 DEGREES WAS SET AT SEATTLE-TACOMA AIRPORT WA.
 
4/20	A RECORD HIGH TEMPERATURE OF 83 DEGREES WAS SET AT WENATCHEE WA.
 
4/20	A RECORD HIGH TEMPERATURE OF 87 DEGREES WAS SET AT THE DALLES OR.
 
4/20	A RECORD HIGH TEMPERATURE OF 90 DEGREES WAS SET AT MEDFORD OR.
 

 
4/21	A RECORD HIGH TEMPERATURE OF 83 DEGREES WAS SET AT BURNS OR.
 
    	A RECORD HIGH TEMPERATURE OF 92 DEGREES WAS SET AT MEDFORD OR.
 
    	A RECORD HIGH TEMPERATURE OF 84 DEGREES WAS SET AT WENATCHEE WA.
 
 	A RECORD HIGH TEMPERATURE OF 85 DEGREES WAS SET AT THE DALLES OR.
 
   	A RECORD HIGH TEMPERATURE OF 82 DEGREES WAS SET AT PORTLAND OR.
 
    	A RECORD HIGH TEMPERATURE OF 81 DEGREES WAS SET AT SALEM OR.
 
    	A RECORD HIGH TEMPERATURE OF 69 DEGREES WAS SET AT SEATTLE WA.
 

 
4/22 	A RECORD HIGH TEMPERATURE OF 84 DEGREES WAS SET AT BEND OR.
 

 
4/24	A RECORD LOW TEMPERATURE OF 30 DEGREES WAS SET AT QUILLAYUTE WA.
 
	A RECORD LOW TEMPERATURE OF 34 DEGREES WAS SET AT SEATTLE WA.
 

 
4/25 	A RECORD LOW TEMPERATURE OF 10 DEGREES WAS SET AT STANLEY ID.
 
4/25 	A RECORD LOW TEMPERATURE OF 24 DEGREES WAS SET AT POCATELLO ID.
 

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US Dept of Commerce National Oceanic and Atmospheric Administration National Weather Service Northwest River Forecast Center (NWRFC) 5241 NE 122nd Avenue Portland, Oregon 97230-1089 Telephone: 503-326-7401 Last Modified: May 17, 2007

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