Wednesday, September 28, 2011

Virgin Pacific Front

The fronts we experience in the interior of western Washington and Oregon, or east of the Cascades are generally pretty wimpy affairs, having been highly modified and weakened by the coastal mountains (including the Olympics) and then the higher Cascades.   Wind shifts are generally weak, precipitation intensity moderate, and the structures torn apart by the terrain.

But out over the Pacific, men are men, women are women, and fronts can be well-defined and far stronger.  Until the Langley Hill radar was installed, our knowledge of Pacific frontal features were mainly based on research work done by aircraft and coastal radars completed over relatively short periods during field experiments--Peter Hobb's group at the UW did the classic work on such systems.

Well now we have a wonderful operational radar looking offshore and we had a view of a beauty of a front.

Now we start with a visible satellite picture at 12:45 PM on Monday as the front approached the coast:


Nice looking frontal band, but exactly where is the front? How strong is it?   Well, we don't have to worry anymore folks...we have the Langley Hill radar.  You can see it offshore (below) --a band extending SSW to NNE crossing the NW tip of the Olympic Peninsula.  Notice the corrugations in the front?   Classic...there are cores of heavy precipitation and gaps between them.


Take a look at the observations at Destruction Island (just off the central WA coast) for the last few days--and take a special look on the 26th (times are in UTC-- 12 is 5 AM, 0 is 5 PM).  You can see the trough of low pressure with the front and winds gusting to 60 knots.


Impressive....and stronger than any of the winds that hit Long Island during Irene. 

The strength of such Pacific fronts are not uniform...they are much stronger in the core areas of heavy precipitation than the gaps in between.  Sometimes the frontal characteristics are INTENSE in the cores.  During the 90s we have field experiment called COAST in which we flew the NOAA P3 Hurricane Hunter aircraft into a Pacific front.  The scientists wanted to go out and cross one of the cores to see what it was like.  The NOAA P3 pilots agreed...they had been through many hurricanes, so they were not concerned.   Well, the passage through the core was very, very intense--with several g's up and down and even the coffee pot broke off in the rear of the aircraft.   Several scientist thought they were going to die. The pilots were shaken...no more flights through cores at low levels--this was a lot worse than going through hurricane eyewalls!

DOG Alert

We had a solid spotter report of my lost cockapoo in Mountlake Terrace near Terrace Creek Park...if any of you live or work up there can you keep an eye out?  For a picture of her, check the link on the right.  Thank you so much. 
http://misscockapoo.blogspot.com/2011/09/missing-black-female-cockapoo.html
Here is where she was seen:


Reminder:
Friday, September 30th 6-8pm
West Seattle Meet & Greet Happy Hour with Candidates Marty McLaren & Sharon Peaslee (and I will be there too!).   Refreshments, of course.
TOPIC: Improving Math, Science and STEM in SPS
7020 18th SW (north of SW Myrtle)
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5 comments:

Mike DeMarco said...

The visible satellite picture shows the "Sequim hole" very well. Yes it is real.

JewelyaZ said...

The new radar continues to "wow" me with what we can observe and thereby learn. It seems like the best use of $9 million US Govt (OUR) dollars that I've heard of in a long time!!

I'm also thrilled that someone saw your dog. I hope she's home soon. :-)

Tom Kanady said...

Speaking of fronts... I snapped this picture last Saturday while sailing. This was just before the weak front was moved into the Puget Sound area. Cliff - I thought you might like this cloud. It is a Mother of a Mammatus maker! She was spinning off little clusters of Mammato-Cumulous right overhead. Not the first thing a sailor wants to see but she was harmless. http://www.kanady.com/weather/MammatusMother.jpg

John McBride said...

Cliff, that these fronts form along the jets seems somewhat straight forward. What is less comprehensible to me is why sometimes "cyclones" form.

Are the mechanisms necessary to such formation understood, or somewhat understood? Regardless of whether or not they are explained could you discuss, when you have a moment, perhaps in terms of the formation of well recognized examples of such storms, why and when these mid latitude cyclones form?

Thanks

Big Wave said...

I remember that COAST flight like it was yesterday. CDR Phil was in the left seat & I was in the right. It was night, inky dark and we were heading for that front down low at 500 feet. It showed up as a line of solid red with some purple in it, right across our flightpath, sort of like a line daring to be crossed. And of course we were going to cross it - that's what we were there for. About a minute from impact Phil and I looked at each other and I knew what he was thinking: "We're gonna grab a tiger's tail"... and it was a dinosaur's tail! Down first, then one huge shake up... very sharp, very hard and all I could think of is that we were only 500 ft off that dark cold water... We wrestled Miss Piggy through, got into calmer air, then dusted ourselves off, and the whole crew said "NOOOOOO, we aren't doing that again.." The cockpit G meter said +5 & -2Gs for the penetration...