1. “Strong Squall Line Strikes Western Oregon and SW Washington” Sunday, March 13 th 2011 Steve Pierce, Vice President Oregon Chapter of the American Meteorological Society stevejpierce@comcast.net (503) 504-2075

2. Facts, Stats & Data * Peak gust reaches 55 mph at the Portland International Airport on Sunday, March 13 th 2011 at 3:32pm PDT as strong post frontal squall line moved through metro area! * Portland’s 55 mph gust is the strongest recorded south / southwest wind gust at the airport since January 16 th 2000 (59 mph) = 11 years! * The barometric pressure at Portland jumped nearly 5 mb (WOW!!!) in about 30 minutes between 3:00pm and 3:30pm PDT, ranking with the likes of October 12 th 1962, November 14 th 1981 and December 12 th 1995! * Conditions were nearly calm again within 15 minutes of the initial burst of wind and rain.

3. Saturday (3/12/11) morning’s 12z GFS model output for Newport, Oregon suggested that 850mb (roughly 5,000ft elev) winds would be extremely fast along the coast the following afternoon!

4. Sunday (3/13/11) morning’s 1.33km view of the U of W 12z WRF model forecasted the developing squall line with uncanny accuracy, hours ahead of time. This image is valid at 3pm PDT 3/13/11!

5. This image is valid at 4pm PDT on Sunday 3/13/11 and suggested that the squall line would move through the valley shortly before 4pm PDT. This image shows the potential for 45-50 knot (roughly 50-58mph) gusts from Vancouver to Salem.

6. This image is valid at 5pm PDT and clearly shows the squall line dissipating as it moves into the Cascades.

7. Portland composite radar imagery valid at 2:09pm Sunday 3/13/11

8. Portland composite radar imagery valid at 2:42pm Sunday 3/13/11

9. Portland composite radar imagery valid at 3:13pm Sunday 3/13/11

10. Portland composite radar imagery valid at 3:44pm Sunday 3/13/11

11. Infrared satellite picture valid at 3:45pm PDT Sunday 3/13/11

12. Classic “V” shaped barometric signature, indicating rapid pressure change!

13. 4.6mb pressure rise in about 30 minutes! WOW!

14. Top Airport Wind Gusts Eugene 58 mph Portland 55 mph Vancouver 55 mph Salem 54 mph Troutdale 44 mph Aurora 41 mph Hillsboro 39 mph Corvallis 39 mph Scappoose 35 mph McMinnville 32 mph Kelso-Longview 32 mph

15. Damage in Vancouver, WA. Photo Courtesy: Tyler Mode