Changes next week and new fall/winter outlooks

Enjoying day after day of sunshine?  How much longer will it last?  In this blog we will address this important question, but also take a brief look ahead into November and briefly touch on the winter outlook.  A more detailed winter outlook blog is coming on or near November 1st. 

So why the abundant sunshine and stretch of dry weather?  A persistent ridge of high pressure is the answer.   Here is one model forecast for this Sunday (Oct 21st) showing high pressure deflecting the jet stream well north of our area.

18z GFS forecast of 500mb heights and 250mb winds valid 5 PM PDT Sunday October 21st

This will be a great weekend for yard work.  Especially raking all those leaves!

There is good model agreement that dry weather will last through at least Tuesday morning.  A weak system tracks through late Tuesday and Wednesday but probably won't produce much rain if any.  Models agree of a wetter pattern developing around Thursday (Oct 25th) of next week.  A low pressure system sets up off the coast resulting a mild but potentially wet southwest flow.  Here is one model depiction of what the pattern should look like next Friday. 

18z GFS forecast of 500mb heights and 250mb winds valid 5 PM PDT Friday October 21st

The jet stream (noted by the green and orange shaded colors) becomes aimed at Washington and north Idaho.  The latest 6-10 day Climate Prediction Center outlooks support a wetter pattern as well.

CPC 6-10 Day Precipitation Outlook issued Oct 18 valid Oct 24-28th, 2018 

It's still too far out to talk about rain amounts and will ultimately depend on the exact placement of the jet stream. 

What about November?  The new outlooks issued today (Oct 18th) favor elevated odds of warmer and drier than normal.

CPC November 2018 Temperature Outlook issued Oct 18 

CPC November 2018 Precipitation Outlook issued Oct 18

And what about the winter you ask?  Well an El Nino winter is forecast which has historically brought mild winters to the Inland NW with precipitation more of a wild card.  The new CPC outlooks issued today (Oct 18) mimic this idea as shown below.

CPC Dec 2018-Feb 2019 Temperature Outlook issued Oct 18 

CPC Dec 2018-Feb 2019 Precipitation Outlook issued Oct 18 

But don't think that a mild winter means no significant weather.  Short term significant weather events can and do occur.  In the next blog we will go into more detail with the past three weak El Nino events (2004-05, 2006-07, 2014-15) and look at what happened.

Record dry summer for some, relief in site?

Now that it's October, let's reflect back on the past three months.  Has this summer seemed dry to you?  Summer is after all the driest time of the year and many of our recent summers have been very dry.  Let's take a closer look.

July through September finished much drier than normal over much of the region as the image below shows.

As you can see, just about everyone finished in the bottom 10% (orange shading) in terms of total precipitation.  And several locations in and near the Columbia Basin reported their driest (red shading) July through September on record.  Here is the data below to prove it

You can see from the table above that Wenatchee, Ephrata, Grand Coulee, Lind, and Davenport reported a new record (or record tie) for the lowest July through September precipitation.  Ritzville and Omak came in 2nd, with Spokane and Pullman 3rd place.

And we still have that dry steak going in Ephrata.  After today it will be 109 consecutive days without measurable precipitation.

We are watching a weather system that will spread rain into portions of the area Friday afternoon into Friday night.  Right now the brunt of it should pass south of Interstate 90.  Ephrata will be on the edge.  Here is one model run from late this evening (Oct 3rd) showing rain amounts for Friday.

00z (Oct 4th) GFS Model 12 hour precipitation forecast valid 11 AM - 11 PM PDT Friday, October 5th.

Looking ahead to next week models are advertising a cold trough settling into the region with a possible increased threat of precipitation.   The long range outlooks from the Climate Prediction Center valid Oct 9-13th show high confidence of colder than normal temperatures with slightly elevated odds of wetter than normal. 

Wondering about the winter outlook?  We plan on updating the blog later this month talking about El Nino and its potential impacts for the Inland Northwest.

Weekend of Smoke: Aug 18-19

Washington and north Idaho experienced the worst smoke of the summer (so far) during the weekend of August 18-19. The smoke reduced visibility to a mile or less in many areas and drove air quality into the "unhealty" or "hazardous" range across the Pacific Northwest. By Sunday, the smoke forced many residents indoors. Reduced visibility from the smoke even caused delays at Seatac airport.

The smoke produced an eerie feeling of darkness during the middle of a summer day. Motorists used headlights throughout the day due to the poor visibility. Check out the picture of Coeur d'Alene at 4 PM on Sunday the 19th.

August 19 at 4 PM: Vehicles Using Headlights. Idaho Transportation Department Camera in Couer D'Alene ID

At times, it was tough to see the sun through the thick veil of smoke. The sun is the little bright dot to the left of the radar tower. This picture was taken at the National Weather Service Office just west of Spokane at 6 PM on the 19th. The nearby Spokane International Airport reported 1 mile of horizontal visibility at the time of this photo. 

August 19 at 6 PM: NWS Spokane.

Where are the fires producing all of this smoke? The map below shows the "hot spots" detected by satellites. The red and orange dots indicate active fires across British Columbia, Washington, and Oregon. Other large fires are burning over northern portions of Vancouver Island.

The map below is a computer simulation produced by NASA that forecasts smoke in the atmosphere. The oranges, reds, and pinks indicate high concentrations of smoke. Atmospheric winds have created a huge reservoir of smoke over the western United States with some of the highest concentrations of smoke over Washington, north Idaho, and southern British Columbia.

NASA/GMAO - GOES-5 Forecast CO Biomass Burning valid 00 UTC 20 August, 2018

Air quality across the Pacific Northwest was affected by the smoke. The red dots on the map below represent sensors reporting "Unhealthy" air quality. The purple and dark purple dots are indicative of "Very Unhealthy" and "Hazardous" air quality. The map also has active fires plotted with flame icons.

August 19 at 7 PM: Air Quality Sensors and Active Fires. Pacific Northwest Smoke Cooperators

This high resolution MODIS satellite image shows the thick grey smoke over the Pacific Northwest. The image was taken around noon PDT, and it shows how the air in southeast Washington and the southern Idaho Panhandle was "cleaner" than central and northeast Washington.

MODIS Satellite Imagery: August 19 Noon PDT.

Places like Pullman and Lewiston not only experienced more sunshine on Sunday (Aug 19), but also got much hotter than places shrouded in smoke. The Pullman airport had a high temperature of 90 degrees on Sunday, and Lewiston topped out at 97 degrees. Spokane is only 70 miles from Pullman and was 13 degrees cooler with a high of 77 degrees.

By the evening, smoke spread into southeast Washington and the southern Idaho Panhandle. This animation from Pullman WA shows a wall of smoke arriving before sunset.

When will our smoke situation improve? North Idaho and much of eastern Washington should experience improved air quality by mid to late morning on Monday. The arrival of a cold front will produce gusty north/northeast winds. "Cleaner" air from central Canada combined with the mixing from 15 to 25 mph winds should push smoke toward Oregon and western Washington on Monday. The three images below is a smoke forecast model. The initial is the model smoke depiction for 5 PM Sunday, August 19th.

By 11 AM on Monday, increasing northeast winds should push the thickest smoke into Oregon and western Washington.

By 5 PM on Monday, the reds and pinks representing thick surface smoke should be pushed into western and central Oregon.

June 2018

Much of the United States spent June breaking high temperature records and experiencing a heatwave. The Inland Northwest wasn’t so unfortunate and had yet to reach 90°F in many inland stations, such as Spokane and Pullman. Wenatchee, Omak, and Moses Lake reached a monthly high of 91°F or 92°F, which wasn’t until the last half of June. Eastern Washington and the Idaho Panhandle saw many cool mornings with some low temperatures falling below 40° F in mid-June. For most of the area, it was a dry month with below normal total precipitation values. 

June 2018

Table 1. High & low temperatures and total precipitation for June 2018 with dates

People throughout Washington, especially Spokane, were anticipating the day we broke 90°F. Many say in Spokane that summer doesn’t start until after Fourth of July. While June wasn’t as warm as many expected, most temperatures throughout the month were near normal. So, how did these June temperatures compare to normal? 

Figure 1. Pacific Northwest Average Temperature Departure from Normal

What about the past few years? Let’s take a look at the last six years compared to normal (1981-2010) for a some locations in the area. (All temperatures in degrees Fahrenheit.)

Table 2. Average June Temperatures (2013-2018) vs. Normal 

June 2018 was cooler than last year, but near normal. Considering monthly average temperatures are not expected to be the same, many locations had an average June temperature with very little departure, close to one degree less or greater, from normal.

When comparing average June temperatures, don't forget that 2015 was an abnormally warm month, with numerous stations breaking, or near-breaking, records held for decades. Lewiston's previous record June high temperature of 103°F, from 1925, was broken in 2015 with a high of 111°F on June 28th. With an average almost ten degrees above normal June, this was just one of many locations reaching triple digits (100°F+) and/or breaking a record high June temperature.

Figure 2. Pacific Northwest Percent of Normal Precipitation 

Much of the Inland Northwest (Eastern Washington and Idaho Panhandle) had a much drier than normal month, with many locations not even reaching a monthly total precipitation of half an inch. Lewiston and Pullman received more precipitation than most of the region. They saw more on June 1, 2018 than many locations did all month. In June, Spokane barely broke half an inch, with 0.55", which was not even half the normal total of 1.25". 

Severe Thunderstorm Event: June 25, 2018

An early morning cold front brought strong winds and lightning to northeastern Washington's Ferry and Stevens Counties. Wind gusts reaching speeds above 50 mph brought damage to homes and land north of Spokane near locations such as Republic, WA. Many people confirmed this event's damage with pictures of buildings and hundreds of trees lost in small, localized areas.

CPC 8-14 Day Outlook: Temperature and Precipitation

The Climate Prediction Center 8-14 day outlook (valid July 21-27) continues to show a moderate chance of below normal precipitation (approx. 40-50%) for the end of July. The temperature 8-14 day outlook shows a moderate chance of above normal value (approx. 40-50%). 

The NWS Spokane website, Facebook, and Twitter will always keep you updated. See

 www.weather.gov/otx for the most current forecast. 

   

Hot temperatures likely next week

After a very warm May, the weather has changed for the first half of June with periods of cooler temperatures, rain showers, and thunderstorms. Computer models have remained fairly consistent over the past several days showing strong high pressure developing next week which could bring an extended period of much above normal temperatures. The latest image showing U.S. risk of hazardous temperatures says it all.

This experimental product from the Climate Prediction Center issued today (Jun 11th) shows a high risk (60%) of excessive heat across the Columbia Basin on June 19th and 20th, with a moderate risk (40%) over this same area June 21st and 22nd.  The remainder of Central and Eastern Washington is in a moderate risk June 19-22nd. 

But before the heat, let's talk about the weather this upcoming weekend and how quickly the weather pattern transitions next week.

Here is the pattern for Saturday and Sunday:

12z/June 11th GFS model forecast of 500mb heights and 700-500mb Relative Humidity (image) valid 5 PM PDT Saturday June 16

12z/June 11th GFS model forecast of 500mb heights and 700-500mb Relative Humidity (image) valid 5 PM PDT Sunday June 17

Not good if you have outdoor plans.  A low pressure system moves little, bringing the potential for showers each day and maybe even a few thunderstorms.  Previous model solutions were quicker to move the low out, but now the weekend looks showery.  Note the images above depict relative humidity with the green colors over our region indicating high values of moisture.

After that, models show a quick transition in the weather pattern. The low over Idaho takes a quick jaunt to the southwest, setting up off the California coast with strong high pressure over the Inland NW. 

12z/June 11th GFS model forecast of 500mb heights and 700-500mb Relative Humidity (image) valid 5 PM PDT WED June 20th.

This results in a hot/dry conditions over our region while the low off the California coast possibly draws in much needed precipitation into the southwest.  A large area of heat expands into much of the west as the image below shows.

12z/June 11th GFS model forecast of 500mb heights and 850 mb temperatures (image) valid 5 PM PDT WED June 20

The European model shows a similar pattern

00z/June 11th ECMWF model forecast of 500mb heights and 850 mb temperatures (image) valid 5 PM PDT WED June 20

How hot will it be?  Well it's too far out to narrow down the numbers, but 90s are a good bet for many valleys, possibly touching close to 100° in the hottest locations.  Note that this event is still 8-10 days out, and the details will probably change.  But, don't be surprised by an extended spell of heat starting around Tuesday, June 19th.

May 2018 Recap & Summer Outlook

May 2018 brought above normal temperatures, with some new records, to much of the eastern half of Washington and the Idaho Panhandle. Wenatchee, WA; Winthrop, WA; Mazama, WA; and Bonners Ferry, ID all experienced their warmest May on record. Spokane, WA and Lewiston, ID also had some of their warmer Mays on record; it was in the top 5 warmest Mays for both cities. It was not the typical wet and cool May that we are used to. Many locations received below normal precipitation, but did not reach any new record low totals. However, due to the above average temperatures and remaining snow pack, some lakes and rivers rose to significant heights. Numerous lakes and rivers experienced flooding. The Kettle River, near Ferry, reached a historic crest of 22.54 ft. on May 11^th. 

Monthly Weather Summary - May 2018

Table 1. Average May temperatures with their rank when looking at the previous/current May records

*It is important to note that due to long periods of record, sites of observations may have changed.

Table 2. May 2018 high and low temperatures with date and total monthly precipitation

Temperature and Precipitation Anomalies

When looking at May mean temperature anomalies above, much of Washington east of the Cascades, the Idaho Panhandle, and northwestern Montana had the biggest warm-anomalies in the western United States.

A closer look at May percentile rankings shows that some record warm mean temperatures occurred in the Eastern slopes of the Cascades, which is where you can find record setting Mazama, Winthrop, and Wenatchee in Washington. Most of the Pacific NW was much above normal.

In the Pacific Northwest, the map of May precipitation anomalies displays the drier than normal conditions in much of the region. 

Looking closely at Spokane

For the entire month of May, there were no days with temperatures below 40°F at Spokane Intl. Airport. 

xmACIS Plot showing number of days in May with min temperatures below 40°F (1947-2018)

There have only been two previous years where Spokane's low temperature has failed to fall below 40° F in the month of May: 1957 & 1980. The last time the temperatures dropped below 40°F this year was April 23^rd with a low of 34°F.  This year had the second warmest May low temperature, just below 1957’s record of 42°. 

Summer Outlook

CPC summer temperature outlook issued May 17, 2018

CPC Summer precipitation outlook issued May 17, 2018

The Climate Prediction Center (CPC) outlook is favoring elevated odds of a warmer than average and drier summer (June-July-August) this year for the Northwest. However, this does not mean there will not be periods of cooler weather and precipitation, like we will be seeing this weekend.

Please monitor our website for all of the latest updates: https://weather.gov/spokane

Spring in Spokane, Washington!

Sunset at Huntington Park - May 2018
Photo by, Bryce Williams