The Windstorm of January 10, 1986

January 10, 1986 Level 2.8 Windstorm Data

Gust Velocity

# Times Occurred

Gust Level

44 mph



43 mph



42 mph



41 mph



40 mph



39 mph



38 mph



37 mph



36 mph



35 mph



34 mph



33 mph



32 mph



31 mph



30 mph






Other Stats at a Glance (For Study Site)

Lowest Pressure

Avg Peak Above 29 mph

# Trees W/Major Damage


33.006 mph



The January 10, 1986 storm was completely monitored. This was another high wind event generated with shallow low pressure, and is an example of how little it can take to kick up a gale. The winds were the product of rapidly infilling high pressure behind a fairly strong cold front, as a small low dove inland across the north end of Vancouver Island. The highest winds occurred as the barometer climbed from 30.07" to 30.28" between 18:30 and 22:00 HRS PST (with a rapid rise of pressure from 30.11" to 30.21" between 20:00 and 21:00 HRS). There was a brief period of wind between 14:30 HRS and 16:15 HRS that resulted in a peak gust of 36 mph at my location. At least 15 brownouts occurred during the primary wind period. In looking at the peak gust comparison chart in Table 8 of the Appendix, it might seem like the peak gust of 44 mph recorded at my site was a little on the high side. However, when the peak gusts from locations not in Table One are considered, such as 66 mph at Bangor, 55 mph at Chehalis, 53 mph at Bellingham, and 47 mph at Everett's Paine Field, then a peak of 44 mph doesn't seem all that strong at all.

The January 10, 1986 windstorm didn't catch me as off guard as January 5-6, but it was a bit of an eye opener to see such a weak low produce high winds in places. My expected model for a windstorm included sharp and fairly deep drops in pressure. The January 5-6 and 10 events didn't press the barometers too hard beforehand. All the spunk was the infilling behind their associated fronts and the rapid development of high pressure up the Pacific Coast. Because of my increasing preparedness for these storms, I had even better regional record of this event than the first two. My weather log notes from this storm went as follows:

January 10, 1986: Friday

6:31 AM: 30.04" steady. Cloudy. 0 mph. 42º F steady. [Entries after this time format (hours and minutes) are my own observations from Renton, WA.]

6AM Local Reports:
Sea-Tac--Cloudy, 47º F, SE7, 30.02" falling, LO 43º, rain 0.18"

7AM Local Reports:
Bellingham--Cloudy, 44º F, N6 knots
Everett--Cloudy, 47º F, SE10 knots
Tacoma--Cloudy, 40º F, S3, Fog 1.25 mi vis
Olympia--37º F, S6 knots, sky obscured
Sea-Tac--Cloudy, 43º F, SE5 knots, 30.02" steady

8AM Local Reports:
Bellingham--Cloudy, 44º F, N7 knots
Everett--Cloudy, 48º F, SE9 knots
Tacoma--Cloudy, 42º F, S2, shallow ground fog
Olympia--38º F, SW5 knots, 1.5 mi vis in fog
Sea-Tac--Cloudy, 46º F, SE8 knots, 30.03" rising

8AM Pressure Readings:
SeaTac--1017 mb, Bellingham--1015 mb, Forks--1014 mb,
Astoria--1017 mb, North Bend--1019 mb

9AM Local Reports:
Bellingham--N4 knots
Everett--Cloudy, 48º F, S11 knots
Bremorton--Cloudy, 42º F, SW5
Tacoma--Cloudy, 43º F, 0, ground fog
Olympia--Cloudy, 40º F, SW5 knots, ground fog
Sea-Tac--Cloudy, 46º F, SE6 knots, 30.04" rising

11AM Local Reports:
Bellingham--Cloudy, 62º F, S18-42 knots!
Everett--Cloudy, 48º F, SE11 knots
Bremorton--Cloudy, 43º F, SW5
Tacoma--Cloudy, 45º F, 0, ground fog
Olympia--Cloudy, 42º F, SW3 knots, fog
Sea-Tac--Cloudy, 50º F, SE6 knots, 29.98" falling

2:10 PM: The eastern horizon to 1º up is clear. Otherwise the whole sky is covered. A light rain just started.

2:15 PM: The sky is just about covered. Wind is picking up--to 10 mph.

2 PM Local Reports:
Bellingham--Cloudy, 60º F, S25-35 knots
Everett--Light Rain, 52º F, SE15 knots
Bremorton--Light Rain, 46º F, W6 knots
Olympia--Light Rain, 50º F, SW11 knots
Sea-Tac-- Cloudy, 47º F, S7 knots, 29.93" falling

1 PM Marine Reports:
Astoria--Mostly Cloudy, 50º F, 20-34 knots
Hoquiam--Moderate Rain, 50º F, SW21-26 knots
Forks--Moderate Rain, SE13-28 knots
Hood Canal--S35-43 knots
Port Angeles--SW15-25 knots
Bangor--S16-34 knots
Navy Whidby--SE14-30 knots

1 PM Pressure Readings
SeaTac--1015 mb, Bellingham--1010 mb, Forks--1011 mb,
Astoria--1016 mb, North Bend--1021 mb

3:39 PM: Pressure 30.10" rising rapidly.

3PM Local Reports:
Bellingham--Light Rain, 53º F, S25-46 knots
Everett--Moderate Rain, 50º F, SW22-36 knots
Bremorton--Rain, 45º F, S9 knots
Tacoma--Rain, SW4 knots
Olympia--Rain, 48º F, S9 knots
Sea-Tac--Light Rain, 48º F, S12-22 knots, 29.98" rising rapidly

Revised inland [waters forecast]: 25-40 knots this evening and tonight.

4:18 PM Here: 30.10" and steady. Gusting to 20-35 mph. 48º F. Clearing to west. Light rain.

4:26 PM: 30.08" falling slowly. Wind up to 22 mph now.

4:38 PM: New Warning: Winds 20-35 mph WGT 45 mph here. 55 mph [gust] at Centralia, sustained. NW Interior 20-35 mph WGT 50 mph. Winds will decrease at midnight. Winds should start in the evening.

4PM Local Reports:
Bellingham--Light Rain, 51º F, S18-28 knots
Everett--Light Rain, 48º F, S15-25 knots
Bremorton--Light Rain and Fog, 46º F, SW15-25 knots
Tacoma--Rain, S16 knots
Olympia--Cloudy, 48º F, S12 knots
Sea-Tac--Light Rain, 49º F, S15 knots, 30.06" rising rapidly

4PM Marine Reports:
Hood Canal--S30-48 knots
Forks--SW16-28 knots
Astoria--SW23-38 knots
Bangor--SE40 knots

4 PM Pressure Readings:
SeaTac--1018 mb, Bellingham--1014 mb, Forks--1012 mb,
Astoria--1019 mb, North Bend--1025 mb

5PM Local Reports:
Bellingham--Light Rain, 50º F, S15-26 knots
Everett--Cloudy, 48º F, S14-20 knots
Bremorton--Light Rain, 47º F, S18-28 knots
Tacoma--Partly Cloudy, 48º F, SE14-20 knots
Olympia--Cloudy, 48º F, S14 knots
Sea-Tac--Cloudy, 48º F, S14-20 knots, 30.05" falling, 0.06" rain today

6PM Local Reports:
Bellingham--Cloudy, 52º F, S25-40 knots
Everett--Cloudy, 48º F, SE15 knots
Bremorton--Light Rain, 46º F, S18 knots
Tacoma--Cloudy, 50º F, S14-23 knots
Olympia--Light Rain Showers, 48º F, S16-25 knots
Sea-Tac-- Cloudy, 50º F, S17-27 knots, 30.07" rising

7PM Local Reports:
Bellingham--Partly Cloudy, 52º F, S24-39 knots
Everett--Light Rain, 49º F, SE13 knots
Tacoma--Partly Cloudy, 49º F, S17-30 knots
Olympia--Light Rain, 48º F, S15-23 knots
Sea-Tac--Light Rain, 50º F, S18-25 knots, 30.09" rising

7PM Marine Reports:
Bangor--25-51 knots
Hood Canal--25-40 knots
Point No Point--41 knots
Point Wilson--24 knots
Navy Whidby--36 knots
Smith Island--41 knots
Forks--SW9 knots
Hoquiam--SW20-35 knots

7PM Pressure Readings:
SeaTac--1019 mb, Bellingham--1015 mb, Forks--1019 mb,
Astoria--1024 mb, North Bend--1028 mb

8PM Local Reports:
Bellingham--Rain Showers, 50º F, S21-35 knots
Everett--Partly Clear, 50º F, SW20-41 knots
Tacoma--Cloudy, 51º F, S16 knots
Olympia--Cloudy, 49º F, SW12 knots
Sea-Tac--Light Rain, 50º F, S25-32 knots, 30.11" rising, HI 51º LO 43º

9PM Local Reports:
Bellingham--Cloudy, 50º F, S15-27 knots
Everett--Cloudy, 43º F, SW22-32 knots
Tacoma--Cloudy, 50º F, S16-25 knots
Olympia--Cloudy, 49º F, SW13-20 knots
Sea-Tac--49º F, S17-23 knots, 30.21" rising rapidly

10:00 PM: Winds on coast starting to die down at 9PM PST. Indland S25-40 knots WHG.

10:25 PM: 30.28" rising rapidly.

Looking at the pressure gradients for the January 10, 1986 storm, note that at 13:00 HRS, when the winds began to pick up along the Washington Coast and Northwest Interior, the pressure was 1011 mb at Forks, and 1021 mb at North Bend, making for a S to N gradient of 10 mb. Winds were fairly light in the Puget Lowlands at this time. By 16:00 HRS, the pressure had risen slightly to 1012 mb at Forks and jumped to 1025 mb at North Bend, steepending the gradient to 13 mb. Winds had picked up in the Puget Lowlands, but were still mostly gusting in the 15-20 mph range, with gusts to 28 mph at Everett. At 19:00 HRS the pressure gradient had lessened again, with Forks at 1019 mb and North Bend at 1028, making for a somewhat lax 9 mb gradient. Winds began blowing at a good clip in the Puget Lowlands, however, because of rapid infill (a result of a fairly progressive storm)--note the rapidly rising barometer for Sea-Tac between 20:00 and 21:00 HRS, when the strongest winds were striking many parts of the lowlands (gusts of 25-45 mph in many places).

Examination of the January 10, 1986 Tree Damage

The January 10, 1986 windstorm blew over a dead scouler willow (Salix scouleriana). Save for a new flurry of Douglas-fir (Pseudotsuga menzesii) twigs, that's it. However, it is the lack of major tree damage that is interesting here. The presence of this storm immediately after two others begs the question: Would this storm, had it been the first in the series, have severely damaged more trees than it did? After all, the January 1, 1986 storm was weaker, both in duration and in peak gust. A 44 mph gust hits with 1.6 times the force of a 35 mph gust, assuming each gust has had an equivalent opportunity to approach stable dynamical forces around the striken objects (achievement of stable airflow around an object, such as a tree, yields the maximim potential force from the gust; see the peak gust discussion in How Strong Was That Windstorm?). It is not too unreasonable to assume that every occasion of major tree damage that happened in the January 1 storm would have also happened in the January 10 storm, which would quadruple the visible damage, making for a much more impressive January 10 storm than what actually occurred. It is also concievable that some of the trees that fell in the much larger January 5-6 windstorm, would have succumbed to the January 10 storm if it had been the first of the bunch, making for even a larger mess. Indeed, it seems that the strong January 5-6 storm so thoroughly cleaned out the forests of weak trees that it put the moderate January 10 storm in a category below the marginal January 1 storm in terms of physical damage. This is a significant point. Literally all the most memorable big blows in the Pacific Northwest have also been the first strong wind producers of the season: October 21, 1934, Columbus Day 1962 (though a low did kick up the winds to 60 mph briefly on parts of the Oregon coast on October 11, 1962, winds did not blow incredibly strong in most of the region affected by the following day's much bigger blow), November 14-15, 1981, and December 12, 1995 are in this list. Consider this: Had a windstorm like the November 14, 1981 event happened some weeks before the Columbus Day Storm, would the second blow have produced as much tree damage?

In any event, the January 10, 1986 storm was not the last of the series. Indeed it was right in the middle. The next two blows, which includes the biggest windstorm for the 1985-1986 season (and indeed for the period December 1983 up until I moved), add even more complexity to the very basic questions that I am asking.

Table 3: January 10, 1986 Windfalls Broken Down By Species



Percent of Total

Salix scouleriana



Last Modified: February 26, 2003
Page Created: September 22, 2001

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