Kennewick, Washington

... Month in review for northeast Oregon and southeast Washington for
the month of October 2009...

I. Temperature and precipitation overview

     October 2009 average temperatures were well below normal for
the region. Total precipitation was near to above normal with some
locations in the Blue Mountains and near the Cascade crest around
200 percent of normal.


October 2009 data and departure from normal for selected cities:

                   Max dep min dep Ave dep pcpn dep
                  temp norm temp norm temp norm totl norm
Yakima 59.0 -5.3 33.9 +1.0 46.5 -2.1 0.89 +0.36
Kennewick 61.5 -4.8 40.8 -1.1 51.1 -3.0 1.16 +0.56
Walla Walla 59.3 -6.5 41.6 -2.0 50.5 -4.2 1.55 -0.22
The Dalles 62.3 -4.4 41.9 -0.5 52.1 -2.5 0.66 -0.34
Redmond 57.2 -8.7 30.2 -3.2 43.7 -6.0 1.22 +0.66
Pendleton Airport 58.5 -5.3 37.2 -3.5 47.9 -4.4 1.56 +0.57
La Grande 55.9 -6.7 34.1 -1.3 45.0 -4.0 2.11 +0.85


Ii. Selected records

     temperatures for the month of October 2009 were colder than
normal across the region. The Pendleton Airport reported an average
monthly temperature of 47.9 degrees. This was the second lowest
average monthly temperature for the month of October on record. The
lowest average monthly temperature for the month of October is 47.4
degrees set in October of 1970. The Redmond Airport reported an
average monthly temperature of 43.7 degrees. This was the third
lowest average monthly temperature for the month of October on
record. The lowest average monthly temperature for the month of
October for Redmond is 42.9 degrees set in 2002. The Yakima Airport
reported an average monthly temperature of 46.5 degrees. This was
the third lowest average monthly temperature for the month of
October for Yakima. The lowest average monthly temperature for the
month of October is 45.8 degrees set in 1946.
     The Yakima Airport reported an average maximum temperature of
59 degrees in October 2009. This is the lowest average maximum
temperature for the month of October on record. This beat out the
previous lowest average maximum temperature for the month of October
of 59.2 degrees set in 1950. The Redmond Airport reported an average
maximum temperature of 57.2 degrees in October 2009. This is the
third lowest average maximum temperature for the month of October on
record. The lowest average maximum temperature for the month of
October for Redmond is 55.3 degrees set in 1957.
     A cold front moved southward across the area on October 10th.
Behind the front, skies cleared and winds became light. With colder
air aloft and good radiational cooling, low temperatures dropped
across the region the morning of October 11th. Several locations
broke record low temperatures.

City previous record new record
Joseph, or 19 in 1899 19 (tied)
Meacham, or 15 in 2008 14
Moro, or 28 in 1990 22
Pendleton Airport, or 25 in 2008 19
city of Pendleton, or 22 in 2008 21
Redmond, or 23 in 2006 15
The Dalles, or 32 in 1990 32 (tied)
Goldendale, WA 24 in 2002 22
Kennewick, WA 29 in 1931 28
Sunnyside, WA 23 in 1924 21
Walla Walla, WA 33 in 2008 26
Whitman mission, WA 24 in 1987 18
Yakima, WA 24 in 1990 18

The low temperature of 19 degrees at the Pendleton Airport is the
coldest low temperature on record reported so early in the season
for that station. The previous earliest coldest low temperature for
Pendleton was 23 degrees on October 13, 1969. The low temperature of
18 degrees for Whitman mission is the coldest low temperature on
record reported so early in the season for that station. The
previous earliest coldest low temperature for Whitman mission was 18
degrees on October 22, 1984.

     Cold air remained over the region the following night, with a
few stations breaking record low temperatures again the morning of
October 12th.

City previous record new record
city of Pendleton, or 21 in 2008 21 (tied)
Sisters, or 18 in 2002 17
Bickleton, WA 28 in 2002 25
Dayton, WA 22 in 1899 18
Whitman mission, WA 19 in 2008 18

     a weather disturbance moved across the Pacific northwest
bringing rain to the region on October 13th. Several stations broke
their record 24-hour precipitation totals.

City previous record new record
Pelton dam, or 0.15 in 1993 0.46
Pendleton Airport, or 0.26 in 1980 0.28
Prineville, or 0.25 in 2003 0.28
Redmond, or 0.21 in 1972 0.31
Seneca, or 0.60 in 1980 0.93
Glenwood, WA 0.28 in 1984 0.90
Satus Pass, WA 0.10 in 2003 0.38


Iii. Significant weather

      a strong low pressure system moved across Oregon October 2nd
through the 4th. The cold front with the system brought an
unseasonably cold air mass out of Canada and into the Pacific
northwest. Many locations reported heavy rain, and several locations
above 4000 feet reported the first significant snowfall of the
season. The following table lists snowfall amounts from weather
spotters, community collaborative rain, hail and snow (cocorahs)
observers, and Weather Service snotel sites.

Location snowfall
Tollgate, or 5 inches
Fox, or 6 inches
Long Creek, or 4 inches
Enterprise, or 6 inches
13 SW Mitchell, or 11 inches
Bend, or 7.5 inches

This system also brought damaging winds to portions of eastern
Washington. Several fires were caused by trees falling across power
lines in the Yakima Valley the night of October 3rd. Blowing dust
caused traffic problems as visibilities dropped on Interstate 90.
Further south, in central Oregon, residents reported "dirty snow" in
Bend and dirt on surfaces after the rain evaporated in Redmond. This
unusual weather occurred because the system took the blowing dust in
eastern Washington and transported it into central Oregon where it
was then carried to the ground by falling precipitation. This
mixture of snow and dust created the "dirty snow".

     In the early morning hours of October 11th, a landslide
occurred near Naches, Washington. The slide buried Highway 410,
destroyed two homes and blocked the Naches River. Several other
homes were damaged by the water from the Naches River as it moved
around the blockage. To date, the cause of the slide is still
unknown.