Monday, March 30, 2020

Cold Air Blast and a Few Snowflakes in Western Washington

This is not an April fools prank.

A shot of cold air will push into western Washington late Tuesday and Wednesday, with strong northeasterly winds from the Fraser River Valley extending into northwest Washington, and even a chance some of you will spot some snowflakes.  In April.

The predicted surface weather map for 8 AM April 1st is, well, chilling.  Very cold air (purple/blue colors) is pushing into southern British Columbia, with a low center near the Columbia River bars.  If this was January, I would getting my snow shovel handy.

With cold, dense air and high pressure in southern BC and low pressure over southwest Washington, a large pressure difference (gradient) will develop over the Fraser River Valley,  accelerating cold air into Bellingham and NW Washington.  This is shown by wind gust forecast for 8 AM Wednesday, with winds reaching 35 knots.  The northeasterly flow will then run into the Olympic Peninsula...and as we shall see, bringing low-level snow.

Later in the day, the strong, cold northerly winds will hit Puget Sound.  I will guarantee you one won't feel like April 1st. 

But what about snow you ask?  The accumulated snowfall (not accumulation) through 5 PM Wednesday show lots in the mountains (up to 1-2 feet) and if you look closely you will note a few inches getting close to sea level on the NE side of the Olympics.   Even some sea level or near sea level locations may see a few flakes.

The upside to all this is that our snowpack is getting enhanced, setting us up for plenty of water during the summer and a good omen for the upcoming wildfire season.  If this was a normal year, I would be talking about good skiing--but it isn't.  There is a chance there will be enough snow for some mountain recreation if the quarantines are lifting by the end of the month.  We will see.

So let me give you the online snow experience and view the top of the Crystal Mountain run around 6 PM tonight.

Saturday, March 28, 2020

An Encouraging Weather Forecast

We all need some good news and I will give that to you. 

The weather is going to improve by next weekend here in the Northwest.  Much warmer and even some sun.

But there is also some bad news....we will have to get through a cool/cloudy period first.

Let's face it.  It has been cool and murky this week, a situation that heightened the stress of all the virus news.  Below are the temperatures at SeaTac during the past two weeks, with the normal highs and lows plotted.  Our daily maximum temperatures have been well below normal the last six days.   Like 5-10F below normal.  Plus lots of clouds and light rain.

Tomorrow will be similar and then a much stronger system, with real rain, will hit Monday, associated an unusually energetic upper level trough (see upper level map for 5 PM Monday).   If this was January, we would be worried about lowland snow with such a pattern.

Fortunately, as the week progresses an upper level ridge of high pressure will build along the West Coast and temperatures will rise.   To warm you up, here is the latest forecast for high and low temperatures at SeaTac based on the European Center ensemble forecasting system (running their model many times and taking the average).  High temperatures climb roughly 10 degrees between this weekend/Monday/Tuesday and later in the week.  You will notice that.

The National Weather Service GEFS ensemble of many forecasts shows a cooling trend for a few days, following by warming (see below).  Each forecast is plotted with a line and the black line is the average of all of them.   Warming towards 60F by April 4/5.  

 Southern California will warm into the upper 60s to low 70s....perhaps high enough to slow down the coronavirus there.  Also clearing skies and progression into spring will produce higher ultraviolet

radiation values along the southern tier of the U.S.:  not good news for the virus, which can be degraded or killed by UV.  Below are the forecast UV index for Sunday and Wednesday.  Big improvement over the western U.S.

This is a good time to plant your spring/cool season veggies if you have a garden.  That is my plan this afternoon!