The Short-Lived Windstorm of January 19, 1986

January 19, 1986 Level 1.6 Windstorm Data Gust Velocity # Times Occurred Gust Level 42 mph 1 42 41 mph 2 82 40 mph 0 0 39 mph 2 78 38 mph 4 152 37 mph 3 111 36 mph 2 72 35 mph 2 70 34 mph 4 136 33 mph 5 165 32 mph 9 288 31 mph 15 465 30 mph 13 390 Totals 62 2,051 Other Stats at a Glance (For Study Site) Lowest Pressure Avg Peak Above 29 mph # Trees W/Major Damage 29.71" 33.08 mph 0 Notes The January 19, 1986 windstorm, though short-lived, still kicked up some fairly mean wind gusts at some locations: Astoria 73 mph, Bangor 71 mph, Hood Canal Floating Bridge 64 mph, Evergreen Pt. Floating Bridge 58 mph, Olympia 55 mph, Navy Whidby 47 mph, and Bellingham 46 mph. At my location, wind gusts above 29 mph began at 00:17 HRS on the morning of the 19th, and continued until 01:22 HRS, so lasting about an hour, and the peak gust happened before 00:34 HRS. Olympia recorded sustained winds of 23 mph or greater from 21:55 to 23:20 HRS on the 18th, with gusts of 45 mph or greater from 21:55 to 22:05 HRS, and the peak gust of 55 mph occurred at 21:56 HRS. The lowest barometer in my records was Forks, WA, with 29.60".

The storm of January 19, 1986, is more noteworthy for the rains that it produced on the 18th, ahead of the winds. The NWS office at Sand Point Way in Seattle had a 24-hr total on the 18th of 4.42", a new all-time short duration pcpn record that still stands, I believe. Storm totals, from January 17 to 19, include 5.93" at Olympia, 4.59" at Sand Point Way, 3.37" at SeaTac, and 3.88" at Hoquiam. These rains contributed to much low-level flooding around the area, and several mudslides, a small one which occurred in my study site at the Mine Forest. Like with the previous storms, I kept extensive records on this one. Here's some of the data:

The Role of Drought. As described on my web page dedicated to the drought of 1985, the year before the January 1986 windstorms was among of the driest on record for many Western Washington locations. Trees get stressed under such dry conditions. And trees under stress aren't as capable of defending against attacks from bark beetle, fungi, and a variety of other maladies. Over the hot, arid, summer season of 1985, many trees could have been weakened. The January 1986 windstorms struck during a storm series that signalled the end of the drought. Thus, it is possible that many of the trees that fell in the January 1986 windstorms may have been weakened by the previous dry period. Currently, with my small sample size, I have no way of ruling this idea out. And, indeed, with the number of windfalls after the Storm 4 limited to one, the data may support this concept. The first four storms, it appears, removed about 99% of the weak trees in the study site--trees that may have originally been victims of drought. There is a slight kink. That bump is October 22, 1985, when a squall line struck the Puget Lowlands, and threw wind gusts as high as 30 mph at my site, and up to 35 mph at other locations. These winds did little, except snap some branches off of the cottonwoods in The Forest, and break a couple of small, dead alders. Apparently, if the drought idea is true, then most of the weakened trees weathered this squall, which, in considering my January data, is quite possible, for the band of thunderstorms amounted to a meager level 1.0 windstorm. The gradually-weakening-tree idea intrigues me because of a broader application. If it is true that the drought had a significant role in setting up trees to fall in winter gales, then I wonder how much a typical summer contributes? Spring and summer are a tree's active time. I'd expect many of the dramas that can potentially weaken a tree to play out then. And since gale-force winds are rare in the tranquil growing season, weakening trees can accumulate up until the time of the first significant wind event in the fall-winter, creating a different concept for the Fall Season--it being not only of discarded leaves, but also of falling trees. And consider that interior locations can go through a whole winter of storms without being struck by a significant wind event, which would allow weakened trees to carry over into the next year's count, adding even more to the potential windfall total of any windstorm that may arise.

Table 6: Windfalls Broken Down By Species For All Five Storms Combined Species Count Percent of Total [1] Alnus rubra 11 37.9% Betula papyrifera 9 31.0% Acer macrophyllum 7 24.1% Cornus nutallii 1 3.4% Salix scouleriana 1 3.4%       [1] Totals exclude trees smashed by windfalls, and those not formally catalogued. Table 7: Percent Of Windfalls By Species For Each Windstorm Species Jan 1 Jan 5-6 Jan 10 Jan 16-17 Jan 19 Alnus rubra 9.1% 54.5% 0.0% 36.7% 0.0% Betula papyrifera 22.2% 44.4% 0.0% 33.3% 0.0% Acer macrophyllum 0.0% 14.3% 0.0% 85.7% 0.0% Cornus nutallii 0.0% 0.0% 0.0% 100% [1] 0.0% Salix scouleriana 0.0% 0.0% 100.0% [2] 0.0% 0.0%             [1] and [2] Only a single member of this species fell in all the storms.

Last Modified: February 26, 2003 Page Created: September 22, 2001 You can reach Wolf via e-mail by clicking here. | Forward to Appendix | Back to Jan 16, 1986 | Back to Jan 1986 Intro |