Summer Rain - Winners and Losers

The summer rain event is now over.  A few afternoon showers are still possible for the next few days, but the westerly winds have pushed the high moisture off to the east.  Whether the forecasts were a success or a failure likely depends on where you were located.  

As you'll remember, there was actually 2 stages to this event.  The first on Saturday and Sunday was a low pressure system that moved into the area from the south, bringing with it a lot of monsoon moisture from the desert Southwest.  Stage 2 was are more "traditional" weather system coming at us from the west, which interacted with all of the moisture still in place to create more rain.

For stage 1, here's a map of the estimated rainfall for Saturday and Sunday.  I say estimated because this is based on radar, not on actual rain gauges.  

You can actually see the center of the circulation in the rainfall, down in southeast Yakima county.  This was a little farther south than anticipated.  As a result, the vast majority of the rainfall from state 1 was south of I-90.  Some thunderstorms developed over northeast Washington and the northern Idaho Panhandle as well.  These actually produced some of the heaviest rain, but very localized.

Stage 2 was Sunday night through Monday night.  Again, the estimated rainfall is shown below.

The main energy from this system traveled from the Olympic Peninsula, across the central Cascades, and into southeast Washington.  So there wasn't much of a rain shadow in the Basin which allowed them to pick up a lot of rain.  Many areas of eastern Lincoln county southward to the Tri-Cities received more than 1" of rain.  There was also a large thunderstorm complex that developed near Chewelah on Monday morning and merged with another complex, bringing heavy rain to parts (but not all) of northeast Washington.

The sum of these two images is shown below.  We've already talked about the locations with the heaviest rainfall.  Some of the 'losers' were much of Spokane county, eastern Lincoln and Adams counties (Davenport, Ritzville) and the Palouse (Whitman county), along with southern Bonner county in Idaho.

Another way to look at this is with actual rainfall observations (i.e. not radar estimates) using automated rain gauges.

And lastly, here's a map of manual observations from cocorahs.org

Some notable amounts include:

• Moses Lake - 0.72"
• Priest Lake - 0.54"
• Seven Bays - 0.63"
• Othello - 1.05"
• Almira - 1.06"
• Wenatchee - 0.78"

As you'll notice, many of the highest amounts were in the usually dry Columbia Basin.  This is because the normal Cascade rain shadow only applies when the winds are from the west.  In this case, the wind was from the east.

You might also have noticed that the Deer Park airport only measured a sprinkle from this entire event.  The Agrimet station just south of the airport picked up about 0.07".    It's not often that Deer Park is one of the driest locations in the Inland NW.

As for the upcoming weather, we should see a few light rain showers midday Wednesday, most numerous the farther north and east you go.  But then it should be dry for a week or more. Temperatures will stay in the low to mid 80s through the rest of the week.  Drier air is moving into the region which will allow nighttime temperatures to cool back into the mid 40s to lower 50s.  

Look for a warming trend starting this weekend and continuing into the first half of next week, with temperatures back into the 90s.  It doesn't appear that this will be a long-lived warm spell though.