Overview

February was dry in most of Oregon, with the exception of northeastern counties. Temperatures overall were near normal.

Table 1 is a summary of monthly averages and totals at selected stations throughout the state. Table 2 lists daily temperatures and precipitation for most of the locations listed in Table 1. In Table 3, monthly and seasonal precipitation totals throughout the state are listed. Figure 1 shows the percentage of normal precipitation for the Water Year.

Basin Summary

Here is a summary of precipitation, water supply, and snow pack as of the end of the month, by river basin:

	Precipitation			Snow	Stream Flow		SWSI
BASIN	(1)	(2)	(3)	(4)	(5)	(6)	(7)
OWYHEE	53	73	65	50	37	41	-1.4
MALHEUR	53	77	71	45	11	22	-2.0
GRAND RONDE, POWDER, BURNT	84	82	78	64	103	79	-2.0
UMATILLA, WALLA WALLA, WILLOW	115	106	80	57	111	83	-1.3
UPPER JOHN DAY	119	88	75	57	77	57	-1.2
UPPER DESCHUTES, CROOKED	73	79	74	55	91	60	-0.9
LOWER DESCHUTES, HOOD RIVER	69	86	67	32	81	63	-1.4
WILLAMETTE	67	88	71	40	98	68	-0.1
ROGUE, UMPQUA	55	102	81	56	72	83	+0.1
KLAMATH	47	82	72	53	81	76	-1.6
LAKE COUNTY, GOOSE LAKE	48	85	72	57	60	58	-1.1
HARNEY	77	72	67	38	53	59	-1.6
NORTH COAST	52	83	n.a.	n.a.	89	73	-1.5
SOUTH COAST	53	88	n.a.	n.a.	60	98	-0.3

n.a. Not available

(1) Percent of normal October precipitation, from NOAA Cooperative sites
(2) Percent of normal October precipitation, from Natural Resources Conservation Service (NRCS) SNOTEL sites
(3) Percent of normal October stream flow, from U.S. Geological Survey (USGS)
(4) Surface Water Supply Index, from NRCS (-4 = very dry, 0 = normal, +4 = very wet)

Forecast

The Climate Prediction Center (CPC) predicts above-average temperatures for March as well as for the three-month period ending in May. There are increased chances of below normal precipitation in western Oregon and normal precipitation in eastern Oregon. Oregon Climate Service predicts average temperatures and above-average precipitation for March as well as for the three months.

NRCS Water Supply Narrative
(www.wcc.nrcs.usda.gov)

Water shortages are expected in all basins of Oregon this spring and summer. The storms of February didn''t bring any substantial increase to the mountain snowpack, in fact all basins except the Umatilla, Hood River and Willamette showed a decrease in the snowpack percentages from last month. As of March 1, the snowpack in the mountains of Oregon ranged between 35 percent of average in the Willamette and 69 percent of average in the northeast corner of the state. February precipitation was below average in every basin ranging from 44 percent of average in the Klamath Basin to 88 percent of average in the Umatilla Basin. These February precipitation amounts bring the total precipitation amount since the start of the water year to between 67 percent of average in the Owyhee and Malheur basins and 92 percent of average in the Rogue/Umpqua Basin. There were 1,446,900 acre-feet of water stored in the 27 major irrigation reservoirs of the state, representing 67 percent of average and 44 percent of the capacity. Streamflow forecasts for the spring and summer months dropped from last month and now are between 17 percent of average on the Malheur River near Drewsey and 92 percent of average on the East Fork of the Wallowa River.

KLAMATH BASIN as of March 1, 2003

Water shortages will exist for water users in the basin this season. The snowpack in the mountains of the basin was 58 percent of average, as of March 1, a drop of 9 percent from last month. Last year at this time the snowpack was 112 percent of average. February precipitation was 44 percent of average, the lowest percentage in the state. This meager amount brings the total for the water year to 75 percent of average. At the end of February, the water stored in the irrigation reservoirs of the basin was 80 percent of average. Reflecting the drop in snowpack and the low precipitation amounts the streamflow forecast for the coming spring and summer are between 19 percent of average for the inflow into Clear Lake and 58 percent of average on the Williamson River.

RESERVOIRS

The major irrigation reservoirs of Oregon stored some water during the month of February. As of the end of February, 27 major irrigation reservoirs held 1,446,900 acre-feet of water, an increase of 227,900 acre-feet from last month. The current amount of water stored represents 67 percent of average and 44 percent of the capacity. Last year at this time there was 1,400,600 acre-feet of water stored in the same 27 reservoirs.

STREAMFLOW

Observed streamflows for the month of February were quite variable across the state, with generally below average flows being observed in the Owyhee and Malheur Basin, and near average flows being observed in the Willamette Valley. The streamflow forecasts have dropped from last month, ranging between 17 percent of average on the Malheur River near Drewsey and 92 percent of average on the East Fork of the Wallowa River. The following table summarizes the spring and summer streamflows at selected sites in the state.

		Percent of average
Stream	Period
Owyhee Net Inflow	Mar-Jul	29
Grande Ronde at La Grande	Apr-Sep	47
Umatilla at Pendleton	Apr-Sep	46
Deschutes at Benham Falls	Apr-Sep	72
Willamette MF near Oakridge	Apr-Sep	62
Rogue at Raygold	Apr-Sep	66
Upper Klamath L. Net Inflow	Apr-Sep	54
Silvies nr Burns	Apr-Sep	20

Oregon Climate Service

George H. Taylor, Oregon State Climatologist

Wayne P. Gibson, Programmer/GIS mngr.

Mandy Matzke, Research Assistant/Manager of Data Services

Kelly Jenson, Undergraduate Assistant

Melanie Mitchell, Student Assistant

Sandra Terra, Undergraduate Assistant

Oregon Climate Service, Strand 316,                                 Phone: (541) 737-5705  
Oregon State University                                                      Fax: (541) 737-5710   
Corvallis, Oregon  97331                                                     E-mail: oregon@oce.orst.edu   
                                                                             Web: http://www.ocs.orst.edu