The Upcoming Northwest Heatwave

 Question

On Friday afternoon at 4 PM, where would be the better place to put on your sunglasses and go outside for a warm St. Patrick's Day stroll?

Seattle or Los Angeles?

The surprising answer:  SEATTLE!

To illustrate the stunning situation, here is the latest European Center surface air temperature forecast at that time.    59F in Seattle and even higher over Chehalis and Portland.


In contrast, about 55-56F in LA on Friday afternoon.


A stroll is enhanced by dry weather.  The total precipitation forecast through Saturday at 5 PM, shown below, indicates that Seattle will be dry, with light precipitation in the mountains.

 
In contrast, during the same period, Los Angeles will be inundated by heavy precipitation, with 1-2 inches through Saturday afternoon from San Diego through Santa Barbara.


Let's take a closer look at the upcoming warmth, with Friday being the warmest day.  Here is the predicted surface air temperature at 4 PM Friday,  the warmest hour of that day.

Western Washington will be quite warm, with temperatures ranging from the upper 50s to lower 60s.  Temperatures will be cooler in eastern Washington.


And this blessedly warm day should also have a lot of sun.  Here is the forecast cloud pattern at 2 pm Friday.  Relatively clear over Washington, but with a veil of high clouds moving into Oregon.  You don't want to know about LA.


Why are we enjoying this warm/dry bounty?   On Friday afternoon there will be high-pressure inland and lower pressure offshore, resulting in easterly (from the east) flow over the Cascades (see below for 2 PM Friday).  Thus, air will be compressed (and warmed) as the air descends the western slopes of the barrier.


I asked the machine learning app, Dalle-E, to show me how the nice weather will change Seattle.  Its answer is below.


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