Squall Line!

Taking a look at the radar this morning was sort of like listening to shark theme from JAWS---you knew something intense was about to happen and it was time to take cover. Take a look at the radar graphic from the Camano Island radar at 7:26 AM:

Wow . An intense line of convective cells....sometime known as a squall line... was moving towards us. Green indicate moderate rain and yellow is heavy rain. This line was accompanied by lightning, a shift in wind direction, a burst in wind speed, a drop in temperature, a rapid increase in humidity and a jump in pressure.

Many locations had gusts to 30- 40 mph and at Paine Field in Everett the winds gusted to 58 mph! Several thousand people lost their power as trees hit power lines. Seeing what was happening the National Weather Service put out a severe thunderstorm warning at 8:15 AM.

Here is what happened at the UW today (click on the image to expand)--look at just after 15 at the bottom (that is 7 AM our time). The graph shows changes in wind speed (top), wind direction (second row), then temperature, relative humidity, pressure and precipitation.

A number of locations got .25 to .35 inches of rain as this line passed. Considerable street flooding occurred here in Seattle. The satellite imagery showed the line approaching the coastline a few hours earlier.

The eastern Pacific is full of convective clouds (cumulonimbus) associated with an unstable atmosphere. This complex array of lines and convective areas are not well forecast by current computer models. When the radar is installed on the coast at least we will be able to see them coming.


Talking about convective lines, several of you sent me this cartoon today, which is amazingly appropriate!

Image courtesy of http://xkcd.com/831/

Here is the precipitation map for much of western Washington from the Rainwatch Web site. A swath of 1-1.5 inches was found over Puget Sound. But what has been really exceptional has been the rain stretching from the north Olympic Peninsula into the San Juans. Strong radar echos were locked over that region for hours and rainfall totals of 2-3 inches have occurred in some locations (the pink colors).Talking about rain... a LOT is coming starting Sunday, with the establishment of a significant pineapple express event. And a super warm front. More on that later.