More records - this time coldest October

After record September snow for some cities, we have more monthly records to talk about.  This time it's the cold October.   Here is a look at the October temperature anomalies thus far which shows about 6 degrees below normal for the month.

Mean daily temperature anomaly Oct 1-29th, 2019

Just six degrees below normal may not sound record worthy, but typically colder weather in October doesn't last for prolonged stretches making this month noteworthy.

Why the cold?  Let's begin with the weather pattern we've been in this month.

500mb height anomalies Oct 1st-28th, 2019

Strong high pressure in the Gulf of Alaska has resulted in prevailing northerly flow across the area allowing for several rounds of cold, Canadian air to invade the region.

Three noteworthy cold intrusions have occurred during the month as noted by this temperature graphic from Spokane.

Spokane Airport observed temperatures, normals, and extremes 

The blue vertical bars are observed temperatures.  The top brown line is normal high temperature and bottom brown line normal low temperature.  Notice the temperature graphic starts towards the end of September when historic September snow was followed by cold temperatures which lingered into the first part of October.  Next on the Oct 8/9th a cold system brought a band of heavy wet snow and power outages to portions of NE Washington and North Idaho with 6" Rathdrum and Hayden and 3" at the Spokane Airport.  And now the cold snap to finish out the month following the strong arctic front passage on the 28th where the palouse was especially hit hard with snow and wind.

Several October temperature records have already been broken including Sandpoint, Ritzville, Davenport, Nezperce, and Winthrop.  Soon more locations will likely be added to this list given our cold weather to finish out the month including Spokane, Moscow, and Ephrata.

October temperature records already or likely to be broken

Note these temperature aren't final yet for the month and include average temperature for data received thus far.  But nonetheless, more records are expected to be broken.

The graphic above summarizes the records.  If you are interested in seeing the details of the records broken or likely to be soon broken, read on below.  Keep in mind the numbers below are so far.  For example for Spokane the average temperature through Oct 29th was 43.1 degrees.  However the average temperature only needs to drop to 42.8 degrees to tie the record and 42.7 to break the record.  Given the cold temperatures on the 30th and 31st, the record is expected to be broken.

Spokane

Spokane, WA top 5 coldest Octobers

Moscow

Moscow, ID top 5 coldest Octobers

Ephrata

Ephrata, WA top 5 coldest Octobers

Sandpoint, ID

Sandpoint, ID top 5 coldest Octobers

Ritzville, WA

Ritzville, WA top 5 coldest Octobers

Davenport, WA

Davenport, WA top 5 coldest Octobers

Nezperce, ID

Nezperce, ID top 5 coldest Octobers

Winthrop, WA

Winthrop, WA top 5 coldest Octobers

Arctic front passage Monday PM

Yet another cold weather system will impact the Inland NW this week.  A strong arctic front passage Monday evening will drop temperatures significantly for mid week.  We will take a brief look at the weather expected with this front and finish with why this is all happening.

Windy conditions will be the main story.  Here are the forecast sustained winds Monday evening as the front passes through.

NWS Forecast issued Sunday afternoon of sustained winds 8 PM Monday, October 28th

Here are the forecast wind gusts.  Orange shading ranges anywhere from 35-45 MPH.

NWS Forecast issued Sunday afternoon of wind gusts Monday afternoon and evening

We are also expecting the potential for a brief period of light snow with the front across NE Washington into the Idaho Panhandle.

NWS Forecast issued Sunday afternoon of potential snowfall Monday afternoon - Tuesday evening

The main threat of accumulation will be up in the mountains of the Idaho Panhandle where 1-2" is possible.  But a dusting of valley snow is possible across NE Washington and North Idaho as well.

The winds will usher in cold wind chills for Tuesday morning.

Forecast wind chills Monday night into early Tuesday morning

Temperatures will begin to moderate for the middle to end of this week but still remain below normal.

Why all this cold weather? 

Anomalous high pressure off our coast sending cold systems into our region from the north.

500mb height anomaly Oct 1-25th, 2019

The cold weather to end October could result in some cities threatening records for the coldest October.  Stay tuned!