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Pacific Northwest Weather Workshop Report – March 5-6, 2010

I traveled up to Seattle this year for the Pacific Northwest Weather Workshop that was sponsored by the NWS, U of W, and the Puget Sound Chapter of the AMS, and was held on the NOAA campus in Seattle.

Friday March 5th:

For me, the highlights of the first session were the description and satellite photos of the Bering Sea Super Storm which resulted in Blizzard Warnings running for about 12 continuous hours in some areas across SE Alaska and the Aleutians. I believe the low peaked at about 955mb which is not unusually strong for the gulf. The record in the Bering Sea/Gulf of Alaska is about 913mb, according to the Alaska NWS staff that were present.

The other area that was interesting from a technical standpoint was the use of Thermal Wind Profiles from rawinsonde and NWS 88D Radar measurements of a developing baroclinic leaf to verify model forecast wind outputs before storm winds reach the shore. Something that should be able to be done with the Washington coastal radar when installed as well!

The second section included a presentation on the UCAR/COMET educational program that offers free online meteorological classes for those that are interested, as well as a variety of other online offerings. This looks like a good place for amateurs and possibly professional mets to improve their weather knowledge and forecast skills.   http://www.comet.ucar.edu/aboutus.htm

Another interesting presentation was on the Tumblebug fire and the effect a thermal trough had on it, first from increased east winds and then from the instability and low dew points induced as the thermal trough passed over it. One item that got a reaction in the room was the -5°F dew point measured at one point. Yes, a -5 dp in September, not during an arctic blast in January! Another area of fire weather that was interesting was the positive correlation between Downdraft CAPE (DCAPE) and fire growth.

Coastal status amounts/periods appear to be increasing over the last several decades in the Northwest.

The World Wide Lightning Location Network looks very cool:  http://www.wwlln.net/

Saturday March 6th:

The Howard Hanson Dam in Washington looks like a major disaster in the making. The Seattle NWS and local media are partnering to increase lead times for getting flood warnings out to cities and municipalities, in addition to the public. They have also modeled rainfall rate scenarios into their warning criteria.  

The Coastal Radar is going to be awesome! It should be the most advanced radar in the country. Cliff Mass would not tell us where it will be sited, but did mention the final three locations. It looks like it will be close to the coast and will be able to scan from 0 degrees up over a very large area off and inland of the coast, which will give us a much better idea of storm structure and coast range precipitation. 0 degrees is basically straight out parallel to the ground, but of course the earth curves so that the beam rises in height as the earth curves away over distance. This is still much better than a 1 or 2 degree angle. Oklahoma NWS, which manages the radar installations, is being a bit difficult, as the local NWS is requesting that the radar be able to not only scan in a circular motion, but also up and down to read storm structure, and they don't think it's necessary. Cliff thinks it will be installed and operational sometime well-prior to January 1, 2012. And a big shoutout to Senator Cantwell for her efforts from Cliff.

An interesting observation from one presenter is that historic rainfall events in central California actually occur most often in La-Niña patterns and not El-Niños. In fact, the maximum event occurred during a La-Niña. One possibility is that the cold air and the corresponding baroclinic zone are pushed farther south into California, where they can be quite stable, resulting in long-term flooding rains.

There was a good presentation on the rain-snow line in mountains documenting and modeling how orographic forces push down the snow level on the windward side of mountains below what would be expected based on the free-air freezing level. This is partially due to adiabatic cooling as the air flow is pushed up over the mountain.

There was an interesting presentation on the challenges of Nowcasting and the instrumentation used for the 2010 winter Olympics by a Canadian met involved in the effort.

Jay Albrecht gave a presentation on his historical weather program. Definitely a very good effort and already used by others here at the Oregon AMS for historical weather research of station readings and weather charts. Jay has obviously put a tremendous amount of time into this and deserves applause from all of us. 

George Miller gave a brief overview of the work he has done documenting Oregon tornados and gave a few examples of historical Oregon tornadoes. It was interesting to note that the word “Tornado” was not favored by professionals until the more recent past.   

Regarding tornados, there were two presentations on recent Northwest tornados, the Northeast Oregon Mini-Supercell/Tornado and the Buckley-Enumclaw Washington Tornado. What was interesting about the NE Oregon event was that instability indexes were marginal at best due to morning cloud cover, but clearing aided by a dry slot moving over the area allowed the sun to heat the air mass into the corresponding dry air in a very brief period of time and generate the supercell. Regarding the Washington tornado, what came across to me was the difficulty in spotting the signature on weather radar. It could easily be missed on the screen. NWS Seattle was suggesting that, during times when there is a possibility of severe weather, one team member should be dedicated to watching the radar at all times.

Finally, the conference finished with a presentation on weather photography with great examples, of course. If you want to get good pictures, be prepared to be up at anytime of the day or night and pay attention to your weather resources, satellite, forecast, etc.

As for the format of the conference, the 15-minute time slots for presentations were right on the money, and the food and snacks were very good.

Phil Welke
AMS Member