With Rapidly Strengthening Sunshine: High Temperatures are Possible in March

 If the sun feels stronger to you right now, it is not your imagination.   

And this stronger sun and longer days can result in spikes of warmth during the month of March in our region.

First, let's consider the average solar radiation in Seattle over the year (below).  Late February, March, and April are times of rapidly increasing solar radiation at our latitude.

Of course, there are clouds, which reduce surface warming, but even so, March is a time of rapidly increasing solar radiation reaching the surface, as shown by the observed solar energy in 2019 (below).   

As a result of the increased sun (and generally decreasing cloudiness), we can get some amazingly warm days in March.  The plot below shows this year's temperatures (blue bars) and record highs (red) and lows (light blue).

Some March days have gotten as high as 80F, with many in the 70s.    You will also note that the chances of getting really cold (below 20F) end by March 10th.

So, will you get a taste of this welcome warmth this week?   Monday will be the warmest day, with rain and cooler conditions by midweek.

The European Center model is going for 58F on Monday, similar to the UW system.

But the warmth will vary over the region, as shown by the temperature forecast for 4 PM on Monday over Washington State (see below).  Temperatures will exceed 55F over central and southern Puget Sound country and in the lower elevations of the Columbia Basin.

Some isolated lucky folks (e.g., near Olympia) will get to 60F.    

I am planning a nice long run late Monday afternoon...which should be wonderful

Rainshadow on the Wrong Side of the Olympics

As shown below, the Olympic rainshadow is normally on the northeast side of the Olympics, while heavy precipitation is found on the south and southwest side of the barrier.

This configuration is due to the typical southwesterly (from the southwest) winds approaching the barrier during the cool season, resulting in upward motion (and precipitation) on the windward (SW) side and sinking motion (and little precipitation) on the leeward (NE) side.

But something unexpected happened on Tuesday morning.   

The weather radar indicated precipitation in the rainshadow area, with nothing apparent on the southwest side (see below, there is some ground clutter on the SW side from the radar beam hitting some peaks).

A cloud band was quite evident to the north of the Olympics that morning.

Rain gauges picked up modest rainfall north of the Olympics, with precipitation on the dry-sky lovers in Sequim and vicinity.  Surely unwelcome for those hitting the links that morning.

The origin of this backwards situation?   The low-level winds had reversed, with northerly wind approaching the Olympics from the north (see surface wind below).

This situation was associated with high pressure to the north and low pressure to the south (see below), with the wind blowing from high to low pressure.

We will be dry until the middle of next week, after which the atmospheric spigot turns on in a major way.