Why can't we forecast these thunderstorms?

Picture Courtesy of Adam Foster During the Early AM on July 9

Although meteorology has come a long way in the last few decades...there is at least one phenomenon that represents guaranteed employment for atmospheric researchers for many years: thunderstorms and convection. This is a very difficult problem and last night's unforecast western WA lightning display proves the point.

To be fair, my colleagues in the NWS did talk about thunderstorms over the Cascade crest and eastern Washington, and the models did suggest a northward propagating feature that forced them--- but lets be honest here, we simply did not expect the extraordinary lightning show, heavy rain, and hail that struck many around western WA. And this kind of failure has happened many times in the past. And there will be more in the future.

Let me show you a sequence of radar images during the period of biggest action over Puget Sound--for 11 PM, 1 AM, and 2 AM. The reds are pouring rain or hail (or both!). A really strong cell moved from the foothills near Enumclaw and moved over Bainbridge Island before heading northward.

The rainfall totals varied wildly, with some folks getting over half an inch (see map)

But it was not the precipitation that impressed the late night or insomniac crowd: it was the unusual amount of lightning and thunder.

Some of the early signs of potential convection were obvious last night...did you notice the development of mid-level shallow convection before and around sunset? Click on the picture below to see a wonderful video of this phenomenon (again provided by Adam Foster):

http://www.flickr.com/photos/twosevenoneonenineeightthreesevenatenzerosix/7536443214/

This was telling us that there was a layer of air that was relatively unstable....and probably that some organized upward motion was releasing this instability.

In fact, the infrared satellite image at 8:45 PM shows an east-west line of convection to the south...and if you looked at an animation you could see it was moving northward. East of the Cascade crest was surely going to get in, but what about the west?

8:45 PM satellite image

That is where the failure mode was found. Here is the 8 hr forecast (1 AM) from the most sophisticated real-time forecasting system run by the National Weather Service--the High Resolution Rapid Refresh Model (HRRR). Lots of action east of the crest, but virtually nothing on the west side.

The UW high-resolution WRF model (1.33 km resolution) starting at 5 PM in fact did a bit better, but not good enough:

Now it is time for a real treat: Greg Johnson on Hansville on Kitsap has a wonderful HD cam and it caught the lightning very well last night. Take a look:

http://www.youtube.com/watch?v=jGOFI8u2wCo&feature=youtu.be&hd=1

Forecasting convection is very difficult for many reasons. Thunderstorm initiation is complex and highly sensitive to the 3D conditions of the atmosphere. Our models generally lack the resolution to simulate them directly and our kludgy methodology for attempting to do so (cumulus parameterization) is relatively crude. And many more...

SUBMIT YOUR WEATHER PHOTO FOR THE 2013 WASHINGTON WEATHER CALENDAR

The UW AMS Student Chapter is partnering with KING 5 News to create the 2013 Washington Weather Calendar. A photo contest is OPEN and I would like to encourage everyone to submit your best weather or nature photos of Washington State. There is a *$200 cash prize for the winning cover photo* and winning monthly photo entries will receive a free calendar. The deadline to submit photos is July 31st. As the charitable partner of the project, the UW AMS Student Chapter will receive a portion of the proceeds from the calendar sales.

*To submit photos and for more information, please visit this website*:
http://www.king5.com/community/Submit-a-photo-for-the-KING-5-Weather-Calendar-160272225.html

The Weather