Climate and Weather of the Okanogan Highlands

CLIMATE...

Big White Summit - Beaverdell Range, Okanagan Highlands

When considering the climate of the Okanogan Highlands it’s important to note the topographic features of the Pacific Northwest as well as the regional features.  Washington State is between latitude, 46° to 49° north. East of the Cascades throughout the Pacific NW the climate possesses both marine and continental characteristics. Considering its northerly location of this area it’s climate is relatively mild.

Sunset through a Thundercell over the Kettle River Range

Large terrain features, proximity to the Pacific Ocean, and semi-permanent high and low pressure regions located over the North Pacific Ocean are climate controls that combine to produce entirely different conditions within short distances.

Warming and drying of air as it descends along the eastern slopes of the Cascade Range results in near desert conditions of the Okanogan Highlands near the confluence of the Okanogan and Columbia rivers.  As air moves inland, it becomes warmer and drier which results in a dry season beginning in the late spring and reaching a peak in mid-summer. Temperatures can reach 100+ degrees on the hottest days of summer with relative humidity dropping below 10% in the lower elevations.

River flooding through cottonwood grove

Ranges of mountains in the Okanogan Highlands are separated by narrow north-south valleys.  Base elevation is roughly 1,000 and to 6,000+ feet along the higher ridges.  The average annual precipitation of the area increases in a northeasterly direction from under 10 inches in the Brewster area to 30 inches in the northeastern corner of the Highlands.

Mount Bonaparte in January

Winter season snowfall in the Highlands valleys varies from 10 to 100 inches with precipitation increasing in the mountains.  Snow generally occurs in the higher elevations in October with the valleys following by the last of November usually lasting until March.  Its not uncommon at elevations above 5,000 feet to have six to eight feet of snow on the ground the first of April.

Cold air moving southward through Canada, locally referred to as “Northerlies” occasionally cross the higher mountains and follow the north-south valleys into the Columbia Basin substantially cooling the Okanogan Highlands.  Average winter temperatures in the Highlands can be characterized at about 30* day time / 15* night with local variations of 10 to 15*.

Due to the inter-action of the climate control features of topography, the Pacific Ocean and it’s pressure systems and the latitude of the Okanogan Highlands with standard weather of the region is often clear and sunny with four distinct seasons and all the variables that are associated with them. 

WEATHER...
What's the old saying, that probably most everyplace in North America uses, "If you don't like the weather just wait a half an hour, it'll change," and so it does. Change, that is. The weather is constantly changing. Each and every component of the weather is in a continuous state of flux. There are no statics. That said, the Wx of the Okanogan Highlands is, by a large comparison on a fairly even keel. Here is a photographic look as some results of various weather systems that impact the Highlands and their aftermath.
2012 Ferry County Wind Event...

Tree top in a power pole - a common sight for several weeks

This unusual wind event destroyed 700 out of 1,000 miles of electrical power-lines belonging to Ferry County Public Utility District. The storm hit with gusts nearing 100 miles per hour breaking and knocking down tens of thousands of trees, temporarily closing two state highways and numerous county roads.

WA State Highway 21 north of Curlew Lake State Park

 Disaster Declarations started at the local level with the Ferry County Commissioners and within 48 hours, Christine Gregoire, Washington State Governor followed with a state declaration for 16 affected counties. After preliminary FEMA crews surveyed the damage President Obama declared the affected area under a Federal Disaster. 

Once a forested front lawn, now a patch of 20 foot tall Ponderosa pine stumps

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Fire Weather of the Okanogan Highland

Lightning over the Okanogan Highlands

As previously mentioned, the Okanogan Highland is prone to a wildfire ecology a significant contributor to that regime is the climate. Temperate weather combined with landscape and soils create a good environment for growing fuels (flora). Especially important are the hot and often dry summers of the region. With local temperatures reaching 100* for multiple summer days and relative humidity below 20% those fuels become fire receptive. The ignition statistics of wildfires indicate that lightning, in the Highlands, is still the #1 cause of forest fires. And due to weather factors mentioned above dry lightning is not uncommon in this geographic area.

Wildfire Smoke Column with darker Plume

Each year there are hundreds of fire starts in the Okanogan Highland. Over 95% of those fires are controlled during the initial attack phase of the suppression operation, but those fires that continue to grow and develop into complicated forest fires also play a contributing factor in the weather of the area. A smoke column from a Highlands wildfire, as seen in this image can consume thousands of acres and burn for many days before fire suppression forces or a change in the weather bring the fire under control (oft times a combination of both). 

Red Sun Month - August in the Highlands

When dry conditions persist and multiple, large fires occur the area is plagued with a persistent smoke pall which can last for several weeks, as can be attested to during the recent 2012 fire season. Highlands firefighters oft times refer to August as ‘The Red Sun Month’ as this image of an August sunset in the Highlands illustrates.

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1998 Declaration of Disaster – Flooding in Ferry and Stevens Counties

WA State Hwy North of Republic, WA

The floods that struck both Ferry and Stevens counties during a large storm system in June of 1998 did several million dollars in damage washing out roads, shutting down highways, knocking out electrical power as well as damaging homes, farms and infrastructure. What the 1998 floods did not do was to impact the normal flood plains of either county. What I mean by that is there was no river flooding. All of the damages occurred on creeks and streams before reaching the rivers. In fact, other than normal high water run-off for that time of year the river levels were not exceptionally high.

Volunteers Sandbagging in Curlew 

The Federal Emergency Management Agency (FEMA), and the Washington Emergency Management Division (WEMD) reports agreed, the primary flood damage was the result of under-sized and poorly maintained culverts. 

FEMA funding resulted in $1 million to complete long-term disaster recovery projects identified after flooding including efforts to disaster-proof the Ferry County Fairgrounds, to purchase two flood prone properties in Ferry County, and to fund road and culvert projects in both counties. The City of Republic has was also awarded a portion of the funds to improve local drainage.

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More to come - check back soon...