Public Information Statement
Issued by NWS Pendleton, OR

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NOUS46 KPDT 170055
PNSPDT

PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE PENDLETON OREGON
455 PM PDT MON JANUARY 16 2017

...Month In Review for Northeast Oregon and Southeast Washington for
the month of December 2016...

...Top 5 Coldest and Snowiest December on Record for Many Locations...

I.  Temperature and Precipitation Overview

December temperatures were well below average over much of the region
for the calendar month, ranging from approximately 2.5 to 7.5 degrees
below average. Most locations saw cold daytime highs, between 1 to 6
degrees below average. Overnight lows were also very cold for the
month, and average mainly between 5 to 9 degrees below normal.

Total monthly precipitation was below average for the month, in
Washington and above average for the month across much of Oregon.
Precipitation totals ranged from about 50 to 90 percent of normal in
our Washington locations. Precipitation totals for the month ranged
from 75 to 200 percent of normal for much of eastern Oregon. Snowfall
for the month was generally above to well above average for most
locations. Many locations had top 10 snowiest Decembers on record. For
the main reporting stations, only Yakima was slightly below average for
snow, coming up 2.3 inches short of their normal.

These very cold temperatures and abundant snowfall lead many locations
to set records for the month. Please see the selected record section
below for more details.

December 2016 Data and Departure From Normal For Selected Cities:

            Max   Dep   Min   Dep   Ave   Dep   Pcpn   Dep   Snow  Dep
            Temp  Norm  Temp  Norm  Temp  Norm  Totl   Norm  Totl  Norm

Yakima       35.5  -0.3  16.5  -4.8  26.0  -2.5  0.87  -0.66  7.4  -2.3
Kennewick    37.5  -2.4  23.8  -5.0  30.7  -3.7  0.74  -0.39  9.0   6.8
Walla Walla  36.4  -2.1  22.8  -5.6  29.6  -3.8  2.06  -0.41  16.9 12.5
The Dalles   37.8  -2.5  25.4  -4.8  31.6  -3.6  2.43  -0.30   M     M
Redmond      35.8  -4.7  12.5  -8.2  24.2  -6.5  1.74   0.58  15.5 10.4
Pendleton    35.4  -4.1  20.8  -6.2  28.1  -5.1  2.29   0.82  18.5 12.5
La Grande    31.9  -5.7  14.8  -8.9  23.4  -7.4  2.73   1.07  9.0   5.8

II.  Selected Records

The first several days of December started off with dry conditions and
above normal temperatures. Snow and colder weather then moved into the
area for much of the rest of the month. Temperatures were well below
average for the second and third week of the month. For the last week
of the month temperatures did moderate some, and a wintry mixture of
precipitation impacted the area. Some plain rain fell at times and much
of the snow melted in the lower elevations. Toward the last few days of
December most of the area remained generally dry. With the deep cold
air impacting the area during the middle of the month and several
significant snow storms, many records were set. The mean synoptic pattern
for the month of December 2016 was characterized by a deep trough of abnormally
low pressure over southwestern and south central Canada. A piece of
this upper level trough also extended to the south over the Pacific
Northwest and the northern tier of the US. A large ridge of high
pressure was also evident across the Aleutian Islands and western
Alaska. This is the classic setup for cold weather in the Northwest,
as a north or northeasterly flow of air develops. December ended
very cold, with much below normal temperatures in eastern Washington
and Oregon. Precipitation amounts were near to above normal for much
of Oregon, while ending mainly below normal in Washington. Snowfall
was near to above average for much of the area. A deep snowpack has
been established for many of the area mountains.

The persistently cold temperatures through much of the month allowed
many temperature records to be set across the entire area. Snowfall
totals were also well above average and allowed several locations to
set records.

Listed below are the locations, rank, December 2016 daily low
temperature, and the current or previous December daily record Low:

City            Rank    December 2016    Current or Previous December
                        Daily Low       Record Daily Low Temperature

Pasco, WA        #1      -9 on 12/17     -6 on 12/16/2008
Hermiston, OR    #2     -13 on 12/17    -16 on 12/16/2008
Sunriver, OR     #5(T)  -14 on 12/17    -27 on 12/08/2013
La Grande, OR    #8(T)   -7 on 12/19    -18 on 12/23/1983
Meacham, OR      #10    -15 on 12/17    -28 on 12/21/1998

Listed below are the locations, rank, December 2016 average high
temperature and the current or previous coldest December average high
temperature:

City            Rank    December 2016    Current or Previous
                        Avg Max T          Dec Avg Max T

Sisters, OR     #1      33.5 Degrees     33.8 Degrees in 2009
John Day, OR    #2      33.6 Degrees     31.1 Degrees in 1983
Cle Elum, WA    #3      29.6 Degrees     27.5 Degrees in 1983
Grizzly, OR     #3      35.1 Degrees     30.6 Degrees in 1983
La Grande, OR   #3      31.9 Degrees     30.1 Degrees in 1983
Long Creek, OR  #3      33.5 Degrees     31.9 Degrees in 1990
Meacham, OR     #4      29.2 Degrees     26.8 Degrees in 1972
Pasco, WA       #4      36.6 Degrees     34.1 Degrees in 2009
Redmond, OR     #4      35.8 Degrees     30.1 Degrees in 1983
Goldendale, WA  #4      33.1 Degrees     29.4 Degrees in 1919
Hermiston, OR   #5      36.9 Degrees     33.6 Degrees in 2009

Overnight low temperatures were often quite cold through the month.
This resulted in numerous top 5 coldest average monthly minimum
temperatures for the month. Listed below are the locations, rank,
December 2016 average min temperatures, and the current or previous
coldest December average min temperature:

City             Rank     December 2016        Current or Previous
                          Average Min T        Coldest Dec Avg Min T

Redmond, OR      #1       12.5 Degrees       14.0 Degrees in 2008
Sunriver, OR     #1        9.5 Degrees       13.2 Degrees in 2008
Meacham, OR      #2       13.5 Degrees       13.1 Degrees in 2009
John Day, OR     #2       14.9 Degrees       13.7 Degrees in 1990
La Grande, OR    #2       14.8 Degrees       13.7 Degrees in 1985
Sisters, OR      #2       10.3 Degrees        6.8 Degrees in 1985
Pelton Dam, OR   #3       18.7 Degrees       17.0 Degrees in 1985
Ellensburg, WA   #4       16.7 Degrees       10.1 Degrees in 1948
Hermiston, OR    #4       19.9 Degrees       18.1 Degrees in 2009
Pasco, WA        #4       19.1 Degrees       18.1 Degrees in 2013
Antelope, OR     #4       15.6 Degrees       13.6 Degrees in 1985
Grizzly, OR      #4       13.9 Degrees       11.3 Degrees in 1990
Madras, OR       #4       11.1 Degrees        6.2 Degrees in 1909
Long Creek, OR   #4       14.3 Degrees       10.8 Degrees in 1990
Walla Walla, WA  #5(T)    22.8 Degrees       17.2 Degrees in 1985

The combined overnight lows and daytime highs were much below normal
across the entire area. This lead to many locations recording their top
five coldest Decembers on record. Listed below are the locations, rank,
December 2016 average temperatures, and the current or previous coldest
December average temperature:

City              Rank    December 2016      Current or previous
                          Average T          Coldest Dec Avg T

Meacham, OR       #2      21.3 Degrees       21.2 Degrees in 1972
Redmond, OR       #2      24.1 Degrees       23.0 Degrees in 1983
John Day, OR      #2      24.7 Degrees       23.8 Degrees in 1983
La Grande, OR     #2      23.3 Degrees       21.3 Degrees in 1985
Monument, OR      #2      25.2 Degrees       21.9 Degrees in 1985
Sisters, OR       #2      21.9 Degrees       20.5 Degrees in 1985
Pasco, WA         #3      27.9 Degrees       26.3 Degrees in 2009
Grizzly, OR       #3      25.0 Degrees       23.4 Degrees in 1948
Hermiston, OR     #4      28.4 Degrees       25.9 Degrees in 2009
Madras, OR        #4      23.6 Degrees       21.0 Degrees in 1985
Prineville, OR    #4      26.0 Degrees       23.3 Degrees in 1985
Long Creek, OR    #4      23.9 Degrees       21.3 Degrees in 1990
Pelton Dam, OR    #4      28.3 Degrees       24.5 Degrees in 1985
Ellensburg, WA    #5      24.5 Degrees       18.9 Degrees in 1948
Bend, OR          #5      25.2 Degrees       22.6 Degrees in 1909

Several storm systems moved through the area during the month of
December bringing periods of snow to the entire area. More details on
these storms can be found in the significant weather section below.
Listed below are the city, rank, December 2016 Monthly Snowfall, and
the current or previous highest December, monthly snowfall:

City             Rank    December 2016    Current or Previous
                           Snowfall       Highest Dec Snowfall

Pelton Dam, OR    #1     16.0 Inches      11.0 Inches in 1985
Walla Walla, WA   #2     16.9 Inches      23.4 Inches in 1983
Sunriver, OR      #2     29.8 Inches      30.9 Inches in 2008
Spray, OR         #2     13.8 Inches      22.3 Inches in 2008
Pendleton, OR     #3     18.5 Inches      32.5 Inches in 2008
Dayton, WA        #3     19.0 Inches      24.2 Inches in 2008
Antelope, OR      #3     18.0 Inches      29.0 Inches in 1968
Whitman Mission   #3     14.2 Inches      24.2 Inches in 2008
Meacham, OR       #4     52.0 Inches      68.8 Inches in 1948
Kennewick, WA     #4      9.0 Inches      16.3 Inches in 1955
Madras, OR        #4     16.5 Inches      21.0 Inches in 1909
Condon, OR        #5     17.3 Inches      44.3 Inches in 2008
Arlington, OR     #5      9.0 Inches      13.5 Inches in 1983
Heppner, OR       #5     13.0 Inches      31.0 Inches in 2008

III. Significant Weather

There were several significant weather events across the area during
the month of December, including two significant snow storms, cold air
outbreaks and a system that brought a wintry mix just before the
holidays.

A frontal boundary pushed northward through the area on December 8th and
into the 9th bringing a period of steady snow to much of the region.
Snowfall amounts over the 5 day period were mainly between 5 to 10
inches for most locations. In the mountains, 1 to 2 feet of new snow
fell.

Listed below are sample 6 day snowfall amounts and the lowest
temperature recorded during this event:

Location          Total Snow      Lowest Temperature

Pendleton, OR       6.5 Inches      5 Degrees
Meacham, OR        13.5 Inches    -11 Degrees
Redmond, OR         2.8 Inches      0 Degrees
Pasco, WA           2.0 Inches     13 Degrees
Walla Walla, WA     7.7 Inches     13 Degrees
Yakima, WA          5.1 Inches      8 Degrees
Hermiston, OR       4.9 Inches     12 Degrees
Ellensburg, WA      5.9 Inches     10 Degrees
Bend, OR            8.3 Inches      2 Degrees
Easton, WA         21.0 Inches     12 Degrees
Heppner, OR         5.5 Inches     11 Degrees

On December 14th and 15th a strong area of low pressure passed eastward
across southern Oregon. A cold wedge of air remained in place over much
of Northeast Oregon and southern Washington. Periods of moderate to
even heavy snow developed over the area.  Seven day snow totals of 6 to
15 inches were common over much of the forecast area. The hardest hit
areas were Central Oregon and the Blue Mountains. Temperatures dropped
well below zero in many locations after the snowfall.

Listed below are some sample snow totals and lowest temperatures during
the period.

Location             Total Snow   Lowest Temps

Pendleton, OR         8.6 Inches   -5 Degrees
Meacham, OR          15.6 Inches  -15 Degrees
Redmond, OR          12.7 Inches   -7 Degrees
Pasco, WA             6.0 Inches   -9 Degrees
Walla Walla, WA       7.5 Inches    1 Degrees
Yakima, WA            2.0 Inches   -4 Degrees
Hermiston, OR         3.1 Inches  -13 Degrees
Ellensburg, WA        2.3 Inches   -3 Degrees
Heppner, OR           6.5 Inches    2 Degrees
Easton, WA           10.0 Inches    9 Degrees
Madras, OR           11.0 Inches   -6 Degrees
Bend, OR             13.1 Inches   -2 Degrees
Dayville, OR          4.6 Inches   -2 Degrees
Condon, OR            8.9 Inches   -1 Degrees
Mitchell, OR          7.4 Inches    0 Degrees
La Grande, OR         5.6 Inches   -7 Degrees

A storm system moved through the area on December 23rd and 24th bringing
a mixture or snow, sleet, freezing rain and some rain. Snowfall was
very wet and slick. Numerous accidents were reported on area roadways
due to the wintry mix. This storm system impacted holiday travel around
the region. Listed below are some sample snow amounts and whether
freezing rain was reported.

Location          Total Snow     Freezing Rain

Pendleton, OR     3.4 Inches        Yes
Meacham, OR       7.0 Inches        No
Redmond, OR       Trace             No
Pasco, WA         1.0 Inches        No
Walla Walla, WA   1.0 Inches        Yes
Yakima, WA        0.3 Inches        No
Hermiston, OR     0.1 Inches        Yes
Ellensburg, WA    0.8 Inches        No
Easton, WA        Trace             No
Heppner, OR       1.0 Inches        N/A
John Day, OR      4.2 Inches        No

The latest drought monitor shows improvement over much of the region.
Some D0 and even a very small area of D1 drought is lingering over
eastern, and especially southeastern Oregon. The substantial October
rainfall, periods of rain through November, and periods of snow and
rain in December allowed much of the area to be removed from any
drought categories. The monthly drought outlook for January from CPC
indicates drought removal likely across most of eastern Oregon.  A deep
mountain snowpack is beginning to develop.

Currently, cooler than average sea surface temperatures were observed
in all Nino regions. A La Nina Advisory has been issued, which means La
Nina Conditions are now present. La Nina is slightly favored (55%) to
persist through the upcoming winter months. This La Nina is expected to
remain weak, but will still likely have an impact on the atmospheric
weather patterns into the winter months.

Snowpack is now mainly above normal across the state of Oregon as of
January 1st. Much of the state ranged from about 95 to 135 percent of
average snow water equivalent. The snow pack has rapidly increased to
between 105 to 175 percent of normal across the state of Oregon by
January 12th. In Washington, the snowpack was closer to average; mainly
ranging from 90 to 125 percent of normal.

Looking ahead to the rest of January the Climate Prediction Center
(CPC) is calling for most of the Inland Pacific Northwest to have a 60
percent chance for below average temperatures in the month of January.
Temperatures will see a brief warm up toward the middle of the month,
but then should turn colder again toward the end of January.

Much of eastern Washington and eastern Oregon have higher probabilities
for above average precipitation totals in January. A period of heavier
precipitation is expected during the middle of the month. Please
remember that these are probabilities of averages, and that the day-to-
day weather will still vary for the month.

$$

MIR201612



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