The Sou'wester of January 15-16, 2000

compiled by

Wolf Read

The sou'wester of January 15-16, 2000 followed a path similar to the powerful storms of October 26-27, 1950, October 12, 1962, March 25-26, 1971, November 13-14, 1981 and December 12, 1995. The closest track match appears to be March 24-26, 1971, though the 2000 low didn't make a landfall on the Washington Coast like the 1971 cyclone did. The January 16, 2000 storm possibly had slightly less punch than the fairly strong 1971 event, but differences in wind measure between the two time periods confuse the issue. This is discussed more in the peak wind and gust section below.

Figure 1, below, shows the track of this storm based on examination of satellite photos and, for the north section, pressure and wind reports in and offshore of Washington and Northwest Oregon. This cyclone moved quite slowly, which may have been a contributing factor for lower wind speeds in the interior sections of the Pacific Northwest. Forward speed was especially slow off of Southwest Oregon, at a time when the cyclone abrubtly turned from a northward course right on 130º W to more of a north-northeast track that eventually took the storm's center just west of Tatoosh Island and into British Columbia.

Sources: Satellite photos were obtained from the National Weather Service, Spokane, from an online report by Don Moore entitled, "Snow, Sleet, Freezing Rain and then Gusty Thunderstorms Sweep across Eastern Washington and North Idaho on 1/16/00." Weather data are from the University of Washington archived surface observations, and National Data Buoy Center, historical meteorological data.

The water vapor satellite picture below, Figure 2, shows the cyclone at 01:30 PST, about the time the storm's leading front had reached Eugene, OR. A strong dry slot, the dark area behind the front, would move in right behind the front, clearing out the precipitation--for awhile, at least. The cyclone's center is just east of the 130º W longitude line, putting it in position for a high wind event even among inland areas such as the Willamette Valley and Puget Lowlands. This image is courtesy of the National Weather Service, Spokane, from a report by Don Moore entitled, "Snow, Sleet, Freezing Rain and then Gusty Thunderstorms Sweep across Eastern Washington and North Idaho on 1/16/00."

Personal Experience

January 15, 2000: Saturday

08:30 HRS: (Salem, OR) It's a cold morning: 27º to 33º F throughout the Portland region. Looks like a storm system may bomb off of Norcal over the next 24 hours and then shoot north up the coast. That's windstorm material--for tomorrow, if so. If we don't head back to Eureka today, then we could be driving back in this potential storm.

January 16, 2000: Sunday

08:04 HRS: (Eugene, OR, Motel 6 northside) The wind's blowing out of the south, gusting to 20-30 mph or so, with a mostly solid, though shallow, low overcast racing northward. From time to time a patch of blue drifts by. It rained from yesterday afternoon into the night, getting moderate at times, the product of a warm air advection field ahead of the developing storm. With the winds out of the south right now, I suspect the cold front has not arrived yet [note the position of the front in Figure 1, above], and the main part of the storm is yet to come. But I'm not sure, for getting weather info on a Sunday in a hotel with few channels (no weather channel) is hard to do. The rising sun just popped out briefly and lit up the I-5 overpass right out my window. It faded just as quickly.

Figure 3, below, is an enhanced infrared satellite photo of the storm taken at 08:45 PST, about the time I made the above journal entry from a hotel room in Eugene. Note that a secondary enhancement of cold cloud tops had developed over the Willamette Valley by this time, bringing more rain along the leading frontal boundary which had slowed considerably in its trek across Western Oregon as the low bombed offshore. The storm's center had moved to about 45º N and 128º W by this time--north of Eugene's latitude, and quite close to the coast. South winds had become fairly strong in the Eugene area by this time, though they wouldn't reach the devastating proportions of other storms that had followed a similar track. The tertiary band of enhanced clouds in extreme southwest Oregon, next to the southeast shoulder of the bent-back occlusion, appears to be the heavy rain and hail maker that I encountered as I crossed the Coast Range west of Eugene, and took to be the storm's primary cold front. This image is courtesy of the National Weather Service, Spokane, from a report by Don Moore.

January 17, 2000: Monday

15:58 HRS: (Freshwater, CA) We left Eugene at about 09:00 yesterday, fighting a strong south wind as we headed west on 126 and into the coastal range. The cold front hit us there, high in the mountains, bringing in a dark squall, brief bursts of heavy rain and hail, and gusty west winds that certainly reached storm force at times--especially down near the coast at the mouth of the Siuslaw River. The wind blew so hard that ocean-like swells were rolling up-river. The estuary was swollen from all the rain and melted snow: we saw the remnants of what had been quite a deep fall of snow in the coastal hills, say down to about 500 feet, and maybe over 1 foot deep in places. There were many fallen bigleaf maples on the steep hillsides, and a few conifers, probably due to snow loading. Getting back to the wind, it had been a long time since the car was shaken so violently--I was fighting the gale with two hands tight on the steering wheel. Though we missed the brunt of the south winds, which reached 70-mph-plus at Port Orford according to some locals. We had a weaker secondary squall just before reaching 101, and then the sun broke out between heavy showers, some with full thunderheads blossoming over the pacific, many trundling by and stacking up in the mountains. This pattern held all the way down to home, with decreasing wind. We missed most of the showers, to my disappointment.

Figure 4, below, is a Doppler radar pass taken close to the time of the satellite image in Figure 3. A nice rain band, right under the enhanced cloud tops in the above satellite image, resides over the Willamette Valley and Cascade Mountiains. A cluster of showers also shows up nicely in the Klamath Mountains of Southwest Oregon. The showers would soon develop into thunderstorms with hail as they progressed northeastward across the region. This image is courtesy of the National Weather Service, Spokane, from a report by Don Moore.

General Storm Data

Minimum Pressures and Peak Gradients

Table 1, below, lists the lowet barometric pressures achieved during the January 16, 2000 storm for 11 Pacific Northwest locations. This storm had a strong double-dip signature at most of these stations. For many inland stations, the first dip, which appears to have been from the cyclone's leading front, was the strongest. For most of the coastal stations, the second dip, which appears to be the time of the low center's closest approach, was the sharpest, leading to apparent time disparities in the data. For Bellingham, the two dips had the same magnitude, and the earliest occurrence is noted below--the station also reported 29.49" in the hours 12:00 to 14:00. The pressure minimum times for Arcata -> North Bend -> Medford -> Eugene -> Salem -> Portland -> Seattle -> Bellingham mark the arrival times of the leading front fairly well, and the pressure minimum times for Astoria -> Olympia -> Quillayute mark the closest-approach times for the low center. Note the 01:00 minimum pressure at Eugene, and the position of the leading front in the satellite picture shown in Figure 2, above.

Some of the lowest pressures on or near land occurred along the Western Washington coast, with Buoy 46029 near the Columbia River Bar reporting 29.10" (985.5 mb), Buoy 46041 near Cape Elizabeth 29.08" (984.8 mb) at 12:00 HRS PST, DESW1 Destruction Island 29.13" (986.3 mb) at 12:00 and TTIW1 Tatoosh Island 29.15" (987.2 mb) at 14:00.

Source: Pressure data is from the National Climatic Data Center, Unedited Surface Observation Forms (Arcata), University of Washington archived surface observations (most stations), and the National Data Buoy Center historical meteorological data (North Bend CARO3 C-MAN station used in place of OTH).

Location

Lowest
Pressure

Approx Time
of Lowest Pressure

California:    
Arcata

29.51"

22:00 HRS, 15th

Oregon:    
North Bend

29.38"

00:00 HRS, 16th

Astoria

29.32"

07:00 HRS, 16th

Medford

29.45"

00:00 HRS, 16th

Eugene

29.41"

01:00 HRS, 16th

Salem

29.42"

02:00 HRS, 16th

Portland

29.44"

03:00 HRS, 16th

Washington:    
Quillayute

29.20"

13:00 HRS, 16th

Olympia

29.43"

11:00 HRS, 16th

Seattle (Sea-Tac)

29.43"

05:00 HRS, 16th

Bellingham

29.49"

06:00 HRS, 16th

     
AVERAGE

29.41"

 

Table 2, below, lists the maximum pressure gradients achieved during the January 16, 2000 storm for 10 Pacific Northwest measures. In a long-standing ASOS tradition, reporting of sea-level pressure became spotty right at the critical maximum gradient times for a number of measures. Astoria stopped reporting all data after 11:00 in what appears to be a system failure (maybe due to power outage) that reached beyond the station, for the Columbia River Buoy also quit reporting during the same hour. Quillayute's weather robot decided that reporting barometric pressure wasn't necessary during the first two hours of critical pressure rise as the storm passed to the north. Thus, maximum gradients using these stations are the highest from the available data--they may have been higher, for pressure "blackouts" occurred right near peak gradients times. It is no small thing that sea-level pressure was rarely missed back in the good old days when weather monitoring was done by humans and surface observation forms were filled by hand. The ASOS situation has shown no signs of improvement as of the writing of this paragraph (01-2003).

Some of the coastal gradients are decent, but none are records. Many windstorms have exceeded the +23.8 mb (+0.70") OTH-UIL reading. Inland, he EUG-PDX value of +6.5 mb (+0.19") was short of the +8.0 to +10.0 mb (+0.23" to +0.30") that is usually required for destructive winds in the Willamette Valley. The PDX-SEA value of +7.4 mb (+0.22") is similarly short, as is the SEA-BLI reading of +6.3 mb (+0.19"). The PDX-BLI gradient was +12.5 mb (+0.37") at 16:00 HRS, again a bit short for a truly damaging gale.

Source: Pressure data is from the National Climatic Data Center, Unedited Surface Observation Forms (Arcata), University of Washington archived surface observations (most stations), and the National Data Buoy Center historical meteorological data (North Bend CARO3 C-MAN station used in place of OTH).

Location

Max Gradient, mb

Approx Time
of Max Gradient

Coast:    
ACV-OTH

11.8

06:00 HRS, 16th

OTH-AST [1]

13.7

11:00 HRS, 16th

AST-UIL [2]

11.8

14:00 HRS, 16th

ACV-AST [1]

21.6

10:00 HRS, 16th

OTH-UIL [3]

23.8

14:00 HRS, 16th

Interior:    
MDF-EUG

11.8

14:00 HRS, 16th

EUG-PDX

6.5

11:00 HRS, 16th

PDX-SEA

7.4

13:00 HRS, 16th

SEA-BLI

6.3

19:00 HRS, 16th

AST-DLS

-12.9

10:00 HRS, 16th

Table 2 Notes:

[1] AST pressure data missing near the peak gradient period. The listed value could be low.

[2] AST and UIL pressure data missing near the peak gradient period. The listed value could be low.

[3] UIL pressure data missing near the peak gradient period. The listed value could be low.

Pressure Tendencies

Table 3, below, lists the maximum hourly pressure falls and rises achieved during the January 16, 2000 storm for 11 Pacific Northwest stations. Nothing particularly unusual here. Peak hourly falls of -2.1 to -3.1 mb (-0.06" to -0.09") and climbs of +2.3 to +3.4 mb (+0.07" to +0.10") are fairly standard for big storms in the Pacific Northwest. This cyclone had much weaker tendencies than many windstorms on record for the region.

Welcome to the Information Age, era of twitchy machines. Peak gusts reached 66 mph at Astoria by 10:00 HRS PST, and peak sustained winds 35 mph at 11:00. Then the station stopped reporting, which resulted in the storm's pressure climbout phase being unrecorded. Astoria wouldn't go back online until 14:00 on January 17th. Quillayute stopped reporting pressure from 15:00 to 16:00, a critical time period when the barometer jumped 10.0 mb (0.30") in a three-hour span that could have contained a higher value than the +3.4 mb (+0.10") at 18:00. Olympia didn't report pressure for four consecutive observation periods from 12:00 to 15:00, which is the time period of initial climbout, though, in looking at the late maximum barometric rise at Sea-Tac, the +2.8 mb (+0.08") at 18:00 for Olympia is probably the correct maximum value.

Source: all pressure data is calculated from hourly readings obtained from the National Climatic Data Center, unedited surface observation forms.

Maximum Pressure Tendencies for the January 15-16, 2000 Storm

Location

Max
Hrly
Fall
mb

Time of
Max Fall
PST

Max
Hrly
Rise
mb

Time of
Max Rise
PST

California:        
Arcata

-2.1

14:00 HRS, 15th

+2.8

07:00 HRS, 16th

Oregon:        
North Bend [1]

-2.5

22:00 HRS, 15th

+3.0

07:00 HRS, 16th

Astoria [2]

-3.1

02:00 HRS, 16th

MM

MM

Medford

-3.0

00:00 HRS, 16th

+3.2

08:00 HRS, 16th

Eugene

-3.9

01:00 HRS, 16th

+3.3

11:00 HRS, 16th

Salem

-2.6

01:00 HRS, 16th

+2.7

13:00 HRS, 16th

Portland

-2.5

02:00 HRS, 16th

+2.3

18:00 HRS, 16th

Washington:        
Quillayute [3]

-3.0

01:00 HRS, 16th

+3.4

18:00 HRS, 16th

Olympia [4]

-2.1

01:00 HRS, 16th

+2.8

18:00 HRS, 16th

Seattle (Sea-Tac)

-2.4

02:00 HRS, 16th

+2.7

19:00 HRS, 16th

Bellingham

-2.3

04:00 HRS, 16th

+2.6

20:00 HRS, 16th

         
AVERAGE [5]

-2.7

 

+2.9

 

Table 3 Notes:

Also see the above discussion.

[1] The -2.5 mb hourly fall is the last of two occurrences.

[2] Astoria stopped reporting after 11:00 HRS PST, just after pressures started to climb.

[3] Quillayute didn't report sea-level pressure from 15:00-16:00, the time of initial pressure climb.

[4] Olympia didn't report sea-level pressure from 12:00-15:00, the time of initial pressure climb.

[5] Average rise assumes an estimated maximum climb of +3.0 mb at Astoria.

Peak Wind and Gust

Table 4, below, lists the peak wind and gust for eleven key stations in the Pacific Northwest, their direction, and their time of occurrence. "Peak Wind" is a 2-minute average, and "Peak Gust" is a 5-second average. By my own personal methodology, a wind event rates the term "windstorm" when the average peak gust of these eleven stations reaches 39.0 mph (gale force) or higher. This ranking favors those storms that follow a northward path close to the U.S. Pacific Coast, and for good reason--such storms affect the largest land area, and therefore are potentially the most destructive. The January 16, 2000 cyclone followed such a path, with damaging winds striking many points along the way.

With an average peak of 52.5 mph, the January 16, 2000 storm ranked as a high-end moderate windstorm. Moderate windstorms have an average of 45.0 to 54.9, and major windstorms are those that reach or exceed 55.0. Only a handfull of storms have made the majors, including December 12, 1995 with 60.5, November 14, 1981 with 65.9 and October 12, 1962 with 80.5. It should be noted, however, that the peak gust measure for the earlier storms was different. Peak instant gust was noted up to about 1995, with the December 1995 storm's average containing a mixture of intant gusts at some stations and the new ASOS 5-second peak. ASOS hadn't been fully implemented in the Pacific Northwest by December 1995--that took until mid-1996.

Peak gusts recorded during the January 16, 2000 storm are all of the 5-second variety. There's a difference between peak instant gust of the past and the 5-second peak of the modern era. A 5-second average could contain a peak intant reading that is significantly higher--maybe even by a factor of 1.2 (20%), depending on the amount of turbulence at the site. Multiplying the 52.5 average peak gust for the January 16, 2000 storm by 1.2 yileds 63.0, which would put the 2000 storm deeply into the major windstorm category. The disparity probably isn't this strong--an adjustment of 1.05 to 1.10 (5 to 10%) is probably more realistic, as airport-based anemometers tend to be subjected to fairly steady winds due to their typically good exposures. These lower adjustments would put the January 16, 2000 storm in the range of 55.0 to 58.0 for comparison to events like the Columbus Day Storm and November 14, 1981. December 1995 is more tricky, due to the mix of measures--it's probably in the range of 62.0 to 65.0 when adjusted for the difference in peak gust measure.

In the Willamette Valley, the January 16, 2000 windstorm struck the Portland and Salem area fairly hard, while barely reaching gale-force at Eugene. The trend toward higher gusts northward in the Willamette Valley is a fairly typical one for the big sou'westers, but the disparity usually isn't as strong as seen during the 2000 storm. Often the difference between Salem and Eugene is about 5 to 10 mph, not a whopping 21. With Corvallis showing a peak of 44 mph, it seems that much of the South Valley was spared the heavy gusts seen in the north.

The Seattle area stations, including Boeing Field, Renton, the University of Washington, and West Point, showed gusts between 52 and 57 mph, a failry good showing for the region. This puts the January 16, 2000 storm slighty above the 48 to 56 mph gusts recorded during the more recent December 27, 2002 storm.

Sources: National Climatic Data Center, undedited surface observation forms.

Location

Peak
Wind
mph

Direction
Pk Wnd
degrees

Obs Time of
Peak Wind
PST

Peak
Gust
mph

Direction
Pk Gst
degrees

Obs Time of
Peak Gust
PST

California:            
Arcata

29

200º

23:48 HRS, 15th

47

130º

21:20 HRS, 15th

Oregon:            
North Bend

39

180º

05:55 HRS, 16th

51

180º

05:55 HRS, 16th

Astoria [1]

35

180º

10:56 HRS, 16th

66

170º

10:09 HRS, 16th

Medford

21

210º

06:56 HRS, 16th

39

210º

06:56 HRS, 16th

Eugene

29

170º

06:56 HRS, 16th

39

170º

08:14 HRS, 16th

Salem

36

160º

08:56 HRS, 16th

60

160º

08:11 HRS, 16th

Portland

37

180º

09:55 HRS, 16th

59

190º

10:14 HRS, 16th

Washington:            
Quillayute [2]

29

180º

13:49 HRS, 16th

45

210º

17:13 HRS, 16th

Olympia [3]

30

170º

11:56 HRS, 16th

54

160º

10:44 HRS, 16th

Sea-Tac

36

200º

14:56 HRS, 16th

52

200º

14:36 HRS, 16th

Bellingham

47

160º

15:53 HRS, 16th

66

170º

15:54 HRS, 16th

             
AVERAGE

33.4

181º

 

52.5

177º

 

Table 4 Notes:

[1] Highest wind and gust at Astoria before station stopped reporting after 11:00.

[2] No reports from Quillayute from 15:00-16:00.

[3] Apparent power failure killed peak wind (PK WND) reports from 12:00 to 15:00, wind and gust still noted.

Footnotes

2000

References

2000

Last Modified: March 2, 2003
Page Created: January 11, 2003

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