1 / 20

The phenomenon

Mike Warner Professor Cliff Mass University of Washington Department of Atmospheric Sciences March 3, 2007 WESTERLY WIND SURGES THROUGH THE STRAIT OF JUAN DE FUCA. The phenomenon.

melia
Download Presentation

The phenomenon

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Mike WarnerProfessor Cliff MassUniversity of WashingtonDepartment of Atmospheric SciencesMarch 3, 2007WESTERLY WIND SURGES THROUGH THE STRAIT OF JUAN DE FUCA

  2. The phenomenon • Extremely strong west or northwesterly winds will surge through the Strait of Juan de Fuca, with the greatest speeds occurring near the eastern mouth of the Strait. • A high amplitude upper level ridge extending into Alaska and a shortwave trough over southwest BC causes upper level westerly winds over the Strait. • A strong pressure gradient from the western to eastern mouth of the Strait causes westerly winds at the surface.

  3. The result • Falling trees • Huge power outages • Dangerous seas • Extensive property damage • Loss of life

  4. December 17, 1990 – The Elwha Storm • Winds gusting over 60 mph from Edmonds to Whidbey Island • Several fallen trees damaged cars and homes • The ferry Elwha sustained $3 million in damage after being repeatedly slammed against the pier at the Port of Everett. The pier was also badly damaged. • 25,000 homes lost power • Local marinas sustained millions of dollars in damage

  5. December 17, 1990 Seattle Times and The Snohomish County Daily Herald

  6. December 17, 1990 ◄ NCEP 500 hPa reanalysis at 06Z on Dec 18. A high amplitude ridge extends into Alaska and a shortwave trough passes over southwest BC causing upper level westerly winds. ► Surface observation chart at 02Z on Dec 18 (during the hour of maximum winds). Smith Island is recording a 39 knot wind. A pressure difference of 4.6 hPa can be seen between the west entrance of the Strait and Smith Island.

  7. December 17, 1990

  8. …and when you have a ferry graphic, why not use it…

  9. October 28, 2003 – The Ivar’s Storm • Strong winds surged eastward through the Strait behind a strong Pacific front, producing wind gusts exceeding 60 mph from Edmonds to Whidbey Island. • Nearly 100,000 people lost power • One death on Whidbey Island from a tree falling onto a parked car • Partial destruction of Ivar’s restaurant at Mukilteo Landing

  10. October 28, 2003 Seattle Times

  11. Ivar’s “rogue wave” mural …and the carp…

  12. October 28, 2003 500 mb heights overlaying an infrared satellite image from 4 PM PST on Oct. 28. A high amplitude ridge extends into Alaska and a short wave trough over southwest British Columbia causes upper level westerly winds in the Strait. NCEP surface pressure reanalysis at 4 PM PST on Oct. 28. A 4-5 mb pressure difference from the western mouth to the eastern mouth of the Strait, causing a westerly wind at the surface.

  13. October 28, 2003 The MM5 predicted winds near 40 knots (20 m/s) at the eastern mouth of the Strait 24 hours in advance of the storm.

  14. October 28, 2003

  15. Stations Paine Field – KPAE Point Wilson – K53S Race Rocks – CWQK Smith Is. – SISW1 Whidbey Is. – KNUW

  16. Climatology – How often? • Examine data from these stations. • Consider winds in the direction of 250° to 300° and exceeding 30 knots. • Count the number of days in which this occurred over a 10 year period. • How do the different stations compare? • Do we need to modify our parameters? • Do we have any problems with our data? • Which station(s) are a good gauge?

  17. Answers? January 1994 – December 2003 UCAR 30+ knots 250° - 300°

  18. Answers… • The different stations show varying numbers of days • This could be due to using the same parameters on stations that are in very different places • The data sets for some of these stations are incomplete. We are working to fill those time gaps with our own archived data. • Smith Island appears to be a good gauge due to its location and data quality.

  19. What’s next? • Organize a list of several dates where high winds were observed at multiple stations • Look at synoptic patterns and categorize storms • Run composites on similar storms • Dissect our case studies, rerun models • We want to know how many different ways these high winds can occur, what causes them. • Which stations miss out and why? • Publish our results

  20. Acknowledgments • UW Department of Atmospheric Sciences • Professor Cliff Mass • NOAA/NWS • Neal Johnson • UCAR/NCAR • NDBC • NCDC Contact information: mdwarner@atmos.washington.edu cliff@atmos.washington.edu

More Related