Inland Northwest

Temperature

Precipitation

Fire Weather

Significant Events

National

The mild, wet, and windy pattern that dominated much of December 2005 continued throughout the month of January. Storm after storm from the Pacific brought rain and occasional snow to the lowlands, while the mountains continued to pile up the snow.

• The 30-day period from December 19, 2005 through January 17, 2006 was the wettest 30-day period ever in Spokane, for any time of the year! A record 6.58” of precipitation fell, surpassing the old mark of 6.56” set way back in November/December of 1897. This is an impressive amount of precipitation, especially when considering the fact that this is 40% of the annual average of 16.66”.
• The month of January 2006 will go down as one of the warmest and wettest January's on record, not only for Spokane but for much of the country!
• In Spokane, it was the 5th wettest and 7 th warmest out of 126 years of records.
• Lewiston had its 3rd warmest January in 126 years.
• In Ritzville, the 4.15” of precipitation was the wettest January in 108 years of records.
• In Coeur d'Alene, the average temperature of 36.7° made it the warmest January in 91 years of record keeping.

Obviously with all of the warm temperatures, lowland snowfall was hard to come by. Most valley locations received less than half their normal snow in January. The exception to this were the valleys of the eastern Cascades. Holden Village received an incredible 136” of snow for the month, while Mazama picked up 66.2” of snow.

This wet pattern came to a close in the first week of February as one last strong storm moved through the area. Winter #3 started just after Groundhog's Day. Once again, the storm door was shut, leaving our area under dry high pressure for most of the month. Overall though, temperatures were near normal. The exception to this was when a cold arctic air mass pushed into the area on the 16th

While temperatures weren't record breaking for this time of year, they sure felt rather bitter after the nearly two months of mild winter weather. As February drew to a close, the weather had become decidedly more spring-like. Aside from the Cascade valleys, most all of the other lowland locations had little if any snow on the ground.

Taken as a whole, the Spring of 2006 was climatologically fairly close to a normal spring. But as most folks know, spring is best defined as the average of two extremes. It’s those rapid changes in the weather that make spring an interesting season.

March started off in normal fashion, but a cold storm on the 8th changed all that. While most snowfall in March is confined to the late night/early morning hours, this storm was impressive because the snow started at noon and continued until midnight. While the Spokane area picked up 2 to 4 inches, 6 to 8 inches of snow fell in the valleys north and east of the Spokane area.  High temperatures on both the 8th and 9th struggled to make it above freezing. Another cold storm in the middle of the month again brought snow to the valleys of northeast Washington and the Panhandle, but amounts were generally only around 1 to 2 inches.  Kellogg did manage to pick up 4.5 inches. That was essentially winter’s last gasp as temperatures warmed into the 50s for the remainder of the month.

April was somewhat lacking in exciting weather.  Throughout most of the month temperatures generally stayed in the 50s and 60s, which is pretty close to normal.  A cool and wet storm during the middle of the month brought an impressive 10.8” of snow to the town of Winchester, located southeast of Lewiston at an elevation of 4000 feet. After this event the weather was a bit warmer and drier.  The warmth continued right up until the 29th when the mercury reached around 80° for the warmest day of the month. Strong thunderstorms rumbled through the area that evening.

Aside from that final day of April, the weather would continue to be uncharacteristically dry for this time of year.  The first half of May saw very little if any rain. Temperatures continued to be slightly on the cool side of normal, so it didn’t really feel like things were abnormally dry. This changed in a hurry. A strong ridge of high pressure developed over the western U.S. sending temperatures well above normal.  Highs on the 15th through the 18th rose well into the 90s, with the mercury hitting the triple digits at Priest Rapids Dam near Hanford. While it’s not unusual to have one hot day in May before a cold front arrives, the longevity of this hot spell was very unusual for the month of May. Many high temperature records were broken during this period, and some were smashed by nearly 10 degrees!

The heat wave came to an end in a big way. A low pressure trough approached the area very slowly from the west, putting out area in moist southerly flow. This produced showers and severe thunderstorms for 4 days from the 19th through the 22nd. The strongest thunderstorms were generally found in southeast Washington and the Idaho Panhandle. Strong winds and 1 inch hail produced damage in several areas, while heavy rain flooded Lewiston. Temperatures which had been in the 90s on the 18th were only in the 60s and lower 70s two days later. As luck would have it, after a warm middle of May, the weather turned markedly cooler for the Memorial Day weekend. From Friday through Monday, temperatures were  in the 50s and lower 60s with widespread showers and some thunderstorms, making for less than desirable camping conditions.

June started off on a wet foot. Spokane picked up 3.09” of rain for the month, and all of that fell in the first 14 days.  Thunderstorms were common during this period over much of the Inland Northwest. Heavy rains washed out roads near Spangle on the 10th. Two days later thunderstorm rains caused a flash flood and mudslide in the Entiat River valley in the Cascades.  On the 13th an unusual severe thunderstorm developed near Pullman before 7 am and moved northward to the Spokane metro area.  Along the way the storm produced numerous reports of ¾” to 1” sized hail, as well as a flash flood in Spokane washing out a road. The 3.09” of rain ranked as the 6th wettest June out of 126 years.  The weather dried out for the second half of the month, with temperatures warming considerably after the 24th.  Lewiston, Ephrata, Moses Lake, Omak and Wenatchee reached the century mark on the 26th and 27th.

July saw its share of hot weather. While many of the 4th of July weekends in the Inland Northwest are not very summer-like, this year was one of those exceptions. Most locations reached the 90s over the holiday weekend with a few sites topping out around 100°F. Added to that were some thunderstorms that developed in the late afternoon and evening, providing an additional light show for some residents. The start of the fireworks display at Spokane was actually moved up a half hour after NWS meteorologists warned organizers of the thunderstorms headed toward the city. These storms also produced hail up to 1.25” in Harrington and Washtucna. Over the next two days, thunderstorms dropped 1” hail over a large area between Wenatchee and Omak, resulting in considerable damage to the fruit crops. Flash flooding also washed out roads and caused mudslides between Lake Chelan and the Methow Valley.  Strong thunderstorms on the 12th produced damaging winds in the Columbia Basin and in Spokane. Thunderstorm activity ended as a hot high pressure ridge took hold of the area on the 21st. The region sweltered under near record heat for 5 days.  Lewiston hit 100°F or more 7 days in a row, while Wenatchee did it 4 consecutive days and Spokane 3 days. The heat finally broke by the end of the month with temperatures cooling into the 70s and lower 80s, a welcome relief. 

August turned out to be near-average for temperatures, but continued dry. Three notable hot spells occurred during the month, with Lewiston reaching the triple digits each time.  But these hot spells lasted only about 5 days and were followed by a period of below-average temperatures, bringing some relief to Inland Northwest residents. The last cool spell came at the end of the month.  After temperatures climbed into the 90s and lower 100s on the 28th, a very cool Pacific air mass moved onshore.  Temperatures just 2 days later had dropped 30 degrees in Spokane with a high on the 30th of only 63°.  Lewiston experienced a drop of 37 degrees in 2 days.  Locally freezing morning temperatures were observed in Priest Lake and Deer Park. As for moisture, August 2006 was quite dry. Most of the locations along the east slopes of the Cascades did not even measure a trace of rain for the entire month.  The northern Idaho panhandle did pick up some much needed rain from some severe thunderstorms on the 10th.  Hail up to 1 inch also fell from these storms, along with some damaging wind gusts.

Most long-time residents know that summers in the Inland Northwest are often dry.  So was the summer of 2006 that much drier than other summers?  Well, here’s some comparisons to other years for the period of Jun 21 – Aug 31:

• Wenatchee Water Plant (records back to 1931)
• Had only a Trace of rain.  This ties it with 1970 for the driest year for that period.
• Average temperature was76.5, placing it as the 3rd warmest behind 2004 and 1958.
• Spokane Airport (records back to 1881)
• The average temperature of 71.1 ranks 16th on the list of warmest.  2004 is 7th and 1998 is 3rd. 
• The 0.35” of rainfall in this period ties it for 7th driest all time.
• Lewiston Airport (records back to 1881)
• 0.48” of rain during this period ranks 13th driest since 1881.  Only 0.15” of rain fell in 2000, placing it 5th on the list.
• The average temperature during this period was 76.3, which ranks it as the 12th warmest.  2004  came in at 76.8 placing it 6th on the list.

So this summer was quite dry and warm.  But in most cases there have been several summers that were warmer and/or drier than 2006.

While the days get shorter, the sunny skies and mild temperatures make this autumn, the best times of year. September started off in the usual fashion: hot.  The first week of September is typically summer’s last gasp, and this year was no different.  Most locations saw temperatures reaching the 90s, with Lewiston topping out at 97° on the 5th.  But the warm weather eventually gave way to the first cool Pacific air mass in the middle of the month. Daytime temperatures dropped into the 60s and even the mid 50s. What little precipitation we had during the month fell in this period. High pressure built back into the area for some beautiful weather by the end of September. Temperatures warmed back into the 70s and lower 80s, which is as much as 15°s above average for that time of year.

October is typically the month where the Pacific “storm door” starts to open for our region. While the weather systems are typically not very wet, they are more frequent, which was the case in 2006. Aside from a few warm days to start the month, temperatures generally remained near normal for the month, with daytime readings typically in the 50s and 60s. A fairly strong storm on the 15th and 16th brought the bulk of the month’s precipitation.  Deer Park (near Spokane) picked up 1.58” of rain while Sandpoint received 0.92”. The 0.48” of rain at Spokane Airport tied a daily rainfall record for the 15th of October. Temperatures remained near normal through the rest of the month until Halloween approached.  Once again, a cold weather system moved into the region dropping our temperatures significantly below normal. Mountain sites picked up their first significant snowfall of the season. While the past 2 years have seen fairly mild Halloween’s, 2002 and 2003 both saw a pattern similar to 2006, with temperatures at the end of October dropping into the 30s with overnight lows in the teens and single digits. Less than a week later, early morning temperatures were in the 40s and 50s on November 6th. Here is a guide on how to decode a surface observation?

The weather pattern became much more active during November.  A persistent and  strong jet stream from the southwest brought abundant moisture into the Pacific Northwest.  Record flooding occurred west of the Cascades. The strong winds resulted in a significant rain shadow for much of eastern Washington and north Idaho, while the mountainous Cascades and Panhandle regions saw copious rainfall. [ An extended radar loop is available (warning: very large file, click with caution)]. In the Cascades, the lack of a snow pack allowed nearly all of the rain to runoff into the streams and rivers. Typically with a winter snow pack, much of the rainfall would have been absorbed by the snow and retained within the pack. The heaviest rainfall occurred in the central Cascades of Washington, causing the Stehekin and Wenatchee rivers to flood.  An NWS observer in Plain, Washington recorded 3.78” of rainfall in 24 hours on the 6th of November.  This broke the all-time 24-hour precipitation record in Plain of 3.36” set on October 29th of 1967.  The 3-day total rainfall for the event was 5.96” at Plain.

In the Idaho Panhandle, flooding also occurred in a few locations of Bonner County.  Lightning Creek flooded and washed out a road, cutting off several residents.  A mountain sensor at 5400 feet elevation measured 8.4” of rain on the 6th, with a 2 day total of 14.2 inches. The total precipitation for the month was 37”, which compares to an average of 14” for this site.

Even after this event wound down, the parade of storms continued.  Spokane Airport had measurable rain on 20 of the 30 days in November. Only 2 other years (1973 and 1983) had more days of rain during this month.  In addition to precipitation, many of these storms brought a great deal of wind. For Spokane, this was the windiest November since 1990.  The strongest winds occurred on the 13th. Several locations experienced wind gusts greater than 60 mph. Some of the strongest wind gusts included 71 mph near Moscow, 62 mph in western Whitman County, and 59 mph at the Spokane Airport.

By the end of the month, the somewhat mild and windy weather had definitely taken a turn towards more colder and snowy. A very strong Pacific storm moved across the area on the 26th, interrupting travelers attempting to return home at the end of the Thanksgiving weekend.  It brought heavy snow to much of the area, with as much as 5 to 10” of snowfall to valley locations.  In it’s wake, cold arctic air came howling down the Okanogan Valley. Wind gusts up to 59 mph were observed. Temperatures on the morning of the 29th were the coldest of the year thus far.  Priest Lake reported a low temperature of -7 while Mazama and the Waterville Plateau dropped to -11.

 When it was all over, November 2006 will go down in the books as one of the stormier months in the Inland Northwest.  The 4.38” of precipitation at Spokane made it the wettest November since 1983!

The active storm pattern that was evident in November continued into December. The month started dry and cold. Nighttime temperatures dropped into the single digits with some below-zero readings, while daytime readings stayed in the teens and 20s. Gradually the cold air gave way to milder temperatures. Many of the sites that had a few inches of snow on the ground to start the month lost that snow pack as rain and warmer temperatures arrived. But the cold air remained in place along the Cascade east slopes where additional snow continued to fall.

A major storm impacted the Pacific Northwest in the middle of the month. A strong Pacific storm developed off the coast and tracked across southern British Columbia. Initially, the effects of the storm were felt along the Cascades. Light rain on the morning of the 14 th quickly changed to heavy snow. Snowfall rates of 2-4 inches per hour were reported causing numerous traffic problems on both the main thoroughfares and county roads. One to 2 feet of snow fell over the Waterville Plateau and Okanogan Valley, as well as the Cascade valleys. Holden Village received 27.5” of snow in 24 hours while other spotters in the Entiat and Methow valleys picked up 16” of snow.

As the storm moved onshore, the threat changed from snow to wind. High winds were felt from the Columbia Basin and Palouse into the northern mountains and the Idaho Panhandle. Some of the strongest wind gusts included an 81 mph report southwest of Moses Lake and an 88 mph reading south of Moscow. Numerous power outages and downed trees occurred throughout the Inland Northwest.

Following this event, the storm track remained fairly constant, with storms moving into the area from the southwest. While this meant rain for some locations, cold-air damming along the Cascades and northern mountains kept the precipitation in the form of snow, providing for a white Christmas for many folks. A spotter near Cashmere picked up 8.5” of snow on the 23 rd while a spotter near Manson received 15” of snow on the 26 th .