Monday, April 30, 2012

Tornadoes and Tulips: The Mt. Vernon Connection

Or perhaps funnels and flowers.   What is it with Mt. Vernon and funnel clouds during the annual spring Tulip festival?   Remember last year?  On April 29th several folks spotted and photographed a funnel cloud rotating over the famous blossoms (see picture below which I found in a story in the Skagit County Herald).

 Nice mini wall cloud with the funnel (the wider part hanging from the cloud base).

Today, I received an impressive picture of two funnels caught over the tulip fields on Sunday at around 12 PM.  This photo was taken by Chris Evans.

http://spindriftphoto.photoshelter.com/image/I0000L1WR_zt.Y50
 Here is another picture by Janet Cray (found here).  You have to look carefully...

And one more by Donna Pratt:
Parenthetical remark:  isn't wonderful how we can get such pictures today with so many people having cell/smartphones with cameras!  A wonderful time to be a meteorologist!

To be honest with you, I as a little surprised by these funnels.  Yesterday was not very unstable and there was very little precipitation or convection.  Here is the NWS radar at that 12:29 PM. UNIMPRESSIVE.



And here is a blown up view over the area of interest 10 minutes later...a developing cell near Mt. Vernon (green color)...but nothing significant.


And take a look at the high-resolution satellite imagery at 12:30 PM..the arrow is pointing to the convective cell (white spot).....you would not write home to your mother about this.


So the only explanation of this is that there was enough horizontal shear (change of winds in the horizontal) to produce some rotation (we call it vorticity in the business).  A weak updraft spun this weak rotation up, like an ice skater rotating faster as she pulls her arms in.  In my NW weather book I go into this mechanism in some depth.

Why Mt. Vernon in spring?  Spring is the most unstable time of the year, with the atmosphere still being cool and the ground warming up rapidly from a bulked up sun.  Mt. Vernon is near terrain and a place that often has regional horizontal wind shear (flow though the Strait versus flow up or down the Sound).    Both can produce low-level wind shear that can have rotation..rotation that can be spun up by convection.

As an aside...quite a blustery April day today as a fairly strong low pressure passed to our north, setting up a large north-south pressure difference (see map).


Some folks got gusts to 30-40 mph, particularly near the water--branches and leaves were all over the ground as I biked home today from the UW.  Take a look at the winds on the Evergreen Point Floating Bridge...bet there was some serious spray on the eastbound roadway!




Saturday, April 28, 2012

Iconic Confusion

An interesting aspect of the communication of weather forecasts isthe use of weather icons, those little picture with clouds, raindrops, snowflakes and the like.   You have seen them often:

Weather icons are an attempt to quickly and intuitively communicate the type of weather expected, but as we will see, there are some issues.

The National Weather Service is a big user of icons and you will see them strewn across the top of the pages when you get a forecast at a location:

I asked my colleagues in the NWS where these icons came and I was told one of the offices developed them, without the aid of any social scientists or objective evaluations of efficacy.  Now, I am not saying I could do better, but let's say the distinctions between some of them have me scratching my head.    Now what IS the difference between mostly and partly sunny?   Even in graduate school they don't teach this.

Now the difference between showers likely and chance of showers is perhaps a bit subtle
 As are the rain icons, where 20% to 100% get the same treatment.
And the icon for a slight chance of freezing drizzle is enough to send icicle-size shivers down any spine! 
I can imagine what a good chance of heavy freezing rain would look like:

Now the private sector does not have bragging rights about better weather icons.  Here are the state-of-the-art icons used by the Weather Channel:

Not much of a distinction there!  And my friends on KING-5 weather are not exactly consistent in the use of  weather icons, with showers getting raindrops some times, but not during others.


Some media outlets try to communicate the probability of rain by how many raindrops are falling out of the icon clouds...but people confused that with intensity.

So is anyone examining in a scientific way the best approach to developing and testing weather icons?   I am proud to say that such work has been taking place at the University of Washington, under the leadership of psychology professor Susan Joslyn.  Many of you know about our probcast web page, where we present probabilistic weather predictions in an accessible way.   We wanted to have icons for precipitation and Dr. Joslyn created and tested a large number of  possibilities of what she termed Precipicons (a few shown below)



The winner was a pie chart type of presentation:

The probability of precipitation is shown by the raindrop portion, but the probability of not raining is shown explicitly by the solid color.    More work is necessary in such icon research.   The National Weather Service is also very much aware they need to entrain social scientists into their communication efforts and are putting resources in this direction.

Judge Judy and My Lost Dog

My family are still looking for our lost dog (and we continue to get some reports)--we so much appreciate your expressions of support and suggestions.  Recently, it all took an unexpected and somewhat humorous turn.   We got a letter from the producer of the Judge Judy cable show.  They had heard about our filing for damages in small claims court and wanted to fly us down to LA to have Judge Judy adjudicate the issue between us the the woman who lost our dog (Dede Harris, http://www.pet-nanny.biz/, located in North Seattle). Well, I am not going to miss class to fly down to LA for such a show, and do you know how much they would pay for the effort?  $ 250.00  You will not get rich going on Judge Judy.  But you might get on her DVD.


Yelp has again taken off the complaint I put on its web site about her.   You really can't trust Yelp--it appears that negative information is shifted into their "filtered" list---is this due to complaints from advertisers?   Lots of stories about that.  Example.