Summer rain

 East of the Rockies, summer rain is a common occurrence.  But in the Northwest, it's definitely a rarity.  (I might do a blog on historical summer rain to see if there is any sort of trend).

We do have a pattern setting up that is more typical of May than mid-August, and it may bring us some rain starting Saturday through the middle of next week.  This will be due to 2 different storm systems: the first will come from our south, the second from the west.

The satellite image from this morning shows a weather system to our south and east, centered over Wyoming.  If you recall the summer outlook I did back in early June, this pattern brought significant rain to eastern Montana in the spring and was expected to continue through the summer.

This moisture in the intermountain West will move into eastern Montana and the Dakotas over the next couple of days.  But a small piece of this system is actually forecast to move into eastern Washington by this weekend.  This is a pretty odd pattern, so it's been treated with some skepticism.  But the computers have been pretty consistent with their forecasts so confidence is growing.

Just how much rain we'll get is tough to tell.  The rain will be showery (typical for summer) so some will get more and others less.  But the usual rules of who gets more don't always apply in this situation.  Spokane could get more than Newport.  Colville may get more than Sandpoint.  I'll show you what I mean with a few computer forecasts.

First, here's the European model forecast for rainfall through 5pm Sunday.  This has the heaviest rainfall along the Highway 2 corridor from Wenatchee to Spokane.

Next is the U.S. GFS model.  This forecast gives very little to the Basin and has the heaviest rain in the Panhandle with a small finger of rain north of Spokane. 

The UK model is considerably wetter than the GFS, dropping more than an inch of rain on Spokane northward to Chewelah and Cusick.

Lastly the Canadian model is very wet for southeast Washington, not so much north of that.

So what are we to make of all of this?  The current modeling centers are relying more on ensembles of forecasts rather than just one deterministic forecast.  The Europeans run 50 different forecasts, the Americans run 30, the Canadians 20.  They then average these forecasts together to come up with the most likely amount.  But as we've seen, any one location may get nothing or may get a lot more than expected.

Moving from north to south, here's the forecast for Colville.  About a tenth of an inch by Sunday afternoon.

For Newport, the average forecast is for about a quarter of an inch of rain.

Similar for Deer Park

And lastly, Spokane's best forecast would be about 0.15" by Sunday afternoon.

They also generate some additional statistics from these forecasts.  For example, Deer Park has a 55% chance of getting at least 0.01", a 25% chance of getting more than 1/4 inch, and a 3% chance of getting more than 1" of rainfall.

Some of you may have noticed that there is additional rainfall forecast all the way through Tuesday of next week.  This is the second weather system we were talking about earlier.  This will come from the west.  It doesn't bring much moisture with it, but there will be plenty of moisture in our Inland NW atmosphere for this weather system to work with.  Again, this isn't a great pattern for widespread heavy rain, but there's still a decent chance of some showers on Monday and Tuesday.

On a different topic, the votes are in and July 2023 was the hottest July on record in a number of locations.  (Some records go back into the late 1800s, while others only go back to the 1940s).

We've seen this chart before.  It shows the rankings for temperatures in July for a number of locations.  Note all of the dark red "1"s in the desert SW, Gulf Coast and Florida.  This past July was the hottest July on record for these locations. 

The average high temperature in Phoenix for July 2023 was an amazing 114.7F.  That not only made it the hottest July on record (records in Phoenix go back to 1895), but the hottest of any month.  It bested the hottest August on record by a full 4 degrees.  The low temperature stayed above 90F on 19 of the July days.   Lastly, the record for consecutive number of days of 110F or hotter was shattered.