Washington and Banks Lake Rain fall

Thunder Storm near Banks Lake

The State of Washington is usually know for its high levels of precipitation and more specifically, its rain.  The immense amount of rainfall and the low levels of sunshine that the western part of the state receives is no doubt the leading cause of one of the highest suicide rates in the US, however  what most people fail to realize is that the Eastern part of Washington is very arid and averages much higher temps then the east.  Banks lake State park only averages 16 inches or precipitation per year compared to Seattle's nearly 38 inches.

Puget sound during Thunder Storm

These 16'' are yet still greater than its surrounding areas, like Spokane, due to the large scale evaporation from the lake an the ensuing down poor from thunder storms.  Banks Lake has numerous amounts of thunderstorms because its climate  has the perfect ingredients: large amounts of water and evaporation coupled with warm weather and rising warm air fronts that come off of either the Puget Sound or Mt. Saint Helens. 

Notice the mountain ranges and the Puget Sound to the west of Banks Lake State Park

Since Washington has both an ocean and a mountain range its is usually substitutable to thunderstorms.  When water precipitates into the atmosphere it starts the up-drafting phase of cumulus type clouds, but little rain fall actually occurs in this stage, rather in the mature stage when  the moisture turns to liquid and falls creating a down draft which in turn has the potential of making  a gust front.

Weathering and its effects on Nature and People

 Banks Lake state park, located in northwestern Washington, has a very unique climate in which its geographical features undergo large amounts physical weathering.  Due the extreme heat and cold that Banks Lake experiences in its virtually 2-sided climate, Summer and Winter, most of the large rock forms on display there are littered with fissures and joints.  These sizable cracks in the rock face allow for great Rock Climbing and help boost tourism in the off-season.

 With the high levels of rain fall that this Whashington state park experances 9 out of the 12 months, it is not uncommon to see many cracks in large rocks, especially waterfront rocks, due to a mechanical weathering process called Frost weathering.  When water from the lake or from rain seeps into small exicting cracks, caused by pressure release,  and freezes it brakes the rock.  Because of the potential of rocks freezing and braking of into the water, once the lake unfreezes each year the park rangers have to drive out and mark off parts of rocks that have fallen into the water so that boaters don’t hit them while driving.
 

Banks Lake Rocks

The extraordinary rock formations that are littered throughout Banks Lake National park and its surrounding cities provide for quite a breathtaking sight.  The rock formations on display there are mostly mafic with felsic rocks being sprinkled in here and there. Basalt rocks make up the majority of the national park and were created by series lava flows and millions of years ago, from a Composite Volcano.

Steamboat rock lies at the center of Banks Lake and is by far the most famous rock there. It has a very unique look, the rock appears to have several almost equal layers all the way to the top.  This was most likely cause by erosion of a pluton after years of separate but compiled lava flows that hardened; and with help from weather and the Columbian River this puton was exposed.  The lava flows that formed Steamboat rock also help explain the existence of numerous solidified horizontals fractures; also know as sills, in other rocks nearby.  These sills and other rock formations such as free standing dikes  are what helps draw people from all over the world and fuel Banks Lakes tourist based economy, especially in the winter when the lake is frozen over.