 |
| Water vapour satellite photo for 15:30 UTC (07:30 PST) 19 Nov 2012. A nice dry slot is evident behind the baroclinic wave that has been devloping overnight. This image also reveals a strong upper-level moisture plume associated with this storm. The system has a decent tropical tap. Image courtesy of the US National Weather Service. |
08:05 PST: (All times in this narrative are PST, unless otherwise indicated.) A frontal wave is
developing nicely, with the tip of a noticeable dry slot reaching 48ºN 129ºW
currently, and the enhanced clouds of a nice comma-head sweeping over Vancouver
Island. The 12:00 UTC HPC surface analysis only indicates a triple-point in the
vicinity of where I would expect the low center t be (near the dry slot tip),
with a widening of the isobars indicating a developing wave. No closed isobars
as of yet. The parent 97.6 kPa stacked-low is just west of Haida Gwaii.
 |
| The Hydrometeorological Prediction Center (HPC) surface analysis overlain on enhanced satellite imagery for 12:00 UTC (04:00 PST) 19 Nov 2012. The most intense pressure gradient was situated over the Oregon coast at this time. |
Environment Canada
has a wind warning up for Vancouver Metro. SE winds are expected to increase
rapidly around midday, reaching 70 to 90 km/h (40-50 kt) at times. Apparently, they are
expecting the triple-point, or perhaps a fully-developed closed low, to pass
across the southern Georgia Strait. However, the National Weather Service,
Seattle, does not appear to be expecting winds of this magnitude in the
Northwest Interior. The current forecast for Bellingham is for breezy
conditions with wind speeds up to 40 km/h (20 kt). In my own experience, this setup
does not appear to have a great probability of significant winds in Vancouver Metro, but things
could change rapidly, so I plan to keep an eye on things as I am working away
on my research.
Coastal areas,
especially Oregon, are getting slammed pretty hard by the developing wave.
Newport reported a S gust to 94 km/h (51 kt) at 23:55 and 05:35. Tillamook
reported winds of S 65 km/h gusting 93 (S 35 kt G 50) at 00:35 and more
recently a gust of S 87 km/h (47 kt) at 07:15. Astoria had a SSW gust of 94
km/h (51 kt) at 05:55. Apparently a spotter measured a 157 km/h (85 kt) wind
gust at Yaquina Head around 00:30, according to the NWS, Portland.
Further north,
Hoquiam at 08:25 reported winds NNE 20 km/h (11 kt), with the temperature
falling from 11ºC (52ºF) at 06:04 to 9ºC (48ºF) at 08:25. The temp at Astoria,
for contrast, is 13ºC (55ºF). The difference in wind direction between the two
stations is classic for a compact low inside 130ºW that is situated north of
Astoria's latitude and south or very close to Hoquiam's latitude. Heavy rain is
falling at Hoquiam, with 10.7 mm (0.42") in the hour ending 07:53.
Periodic heavy rain has also been falling in the north Willamette Valley, with
Hillsboro reporting up to 5.8 mm (0.23") in the hour ending 02:53 and 37.1
mm (1.46") in the 24-h ending 03:53. Strong south winds have been
buffeting the station, with gusts to 63 km/h (34 kt) at 05:53. Interestingly,
winds at Portland have not been as strong, with gusts to 37 km/h (20 kt) at
20:53 last night being the highest so far. Hourly rain totals have been a
little behind Hillsboro, too, with a 26.9 mm (1.06") 24-h total as of
03:53. Apparently, 50-100 mm (2-4") of rain are expected in the Willamette
Valley today, with possible wind gusts in excess of 80 km/h (43 kt) as the wave
moves ashore.
Currently at Vancouver
International: Light rain showers with a temp of 8ºC (46ºF), dew point 7ºC
(45ºF), wind E 20 km/h (11 kt) and pressure 99.75 kPa (29.46" Hg), up 0.5
hPa from a recent minimum during the last hourly observation. 08:43 PST. A wet, gloomy day outside of my window right now.
14:27 PST: The coast
received a serious lashing right after I closed the previous entry. Here are
some peak wind and peak gust reports from key airport stations:
Peak Wind 19 Nov 2012 Coastal Gale
|
|||
Location
|
Time (PST)
|
Direction (º)
|
Speed (km/h) (kt)
|
Newport
|
10:15
|
190
|
78 (42)
|
Tillamook
|
12:35
|
180
|
72 (39)
|
Astoria
|
10:26
|
190
|
65 (35)
|
Hoquiam
|
19:28
|
170
|
67 (36)
|
Quillayute
|
03:53
|
190
|
20 (11)
|
Peak Gust 19 Nov 2012 Coastal Gale
|
|||
Location
|
Time (PST)
|
Direction (º)
|
Speed (km/h) (kt)
|
Newport
|
12:55
|
200
|
107 (58)
|
Tillamook
|
12:35
|
180
|
102 (55)
|
Astoria
|
09:35
|
210
|
119 (64)
|
Hoquiam
|
11:04
|
170
|
98 (53)
|
Quillayute
|
06:53
|
VRB
|
35 (19)
|
Wind speeds have not
been particularly strong at Quillayute. The temperature has not been as high as
places south, either, indicating that this station is on the north side of the
baroclinic band. The cooler air north of the band has sheltered the north
Washington Coast from the warmer, more unstable and much windier air south of
the boundary. The 21:00 UTC HPC surface analysis places a not-very-well-defined
99.2 kPa low pressure center just north of Hoquiam, and south of Quillayute.
Hoquiam just fell under the gun—a few tens of kilometers placement of the
boundary, and low, further south would have resulted in slower winds at the
site. Winds shifted dramatically from NNE 17 km/h (9 kt) at 08:33 to variable
and gusty from 08:40 to 08:53 then accelerating out of the SSE by 08:58. By
09:09, winds were S 37 km/h gusting 52 (20 kt G 28), and the temperature had
risen 3ºC (6ºF) to 12ºC (54ºF) in 35 minutes. The warm sector had arrived,
setting the stage for much faster winds over the next couple of hours.
 |
| The 21:00 UTC (13:00 PST) HPC surface analysis places a weakly-defined low right on the coast of Washington, with a strong southeast pressure slope (gradient) south of the depression. |
Though this coastal
storm proved quite strong, with wind gusts approaching hurricane force at some
official stations, this event is far short of the Great Coastal Gale of
02-03 Dec 2007. However, these two storms do seem similar
in many respects—they rhyme—including a strong tropical tap, a persistent baroclinic band with a train of waves enhancing local wind speeds, much rainfall, and generally higher wind speeds on the western side of the Willamette Valley (see below).
Here in Vancouver,
winds are quite light, with a report of SE 11 km/h (6 kt) at 14:21. The
pressure has become quite low, down to 99.35 kPa (29.34" Hg) at 14:00. At
one point, the pressure fell 2.0 hPa in a single hour between 11:00 and 12:00.
The pressure at Victoria has begun to rise from a low of 99.24 kPa (29.31"
Hg) at 13:00. Winds have been ENE at 13 km/h (7 kt) for the past two
observations, including the most recent one at 14:00. For comparison, low
pressure at Quillayute occurred at 11:53 with a reading of 99.20 kPa
(29.30" alt). At Vancouver, the thermometer at 14:00 indicated 8ºC (46ºF)
and at Victoria 9ºC (48ºF). With offshore winds, cool temps and a barometer
beginning to rise at least in Victoria, it seems that the threat of strong
southeast winds in the region is diminishing. Seems like the triple-point and
weakly-defined low, are likely to pass south of Greater Victoria and Metro
Vancouver.
Moderate to heavy
rain moved through both Victoria and Vancouver between 09:00 and 12:00, this
embedded in a large field of light precipitation.
Generally speaking,
SSE to SSW wind gusts in the Willamette Valley have been in the 50-65 km/h
(25-35 kt) range. However, the west side of the valley seems to have been hit a
bit more strongly than the east side, with McMinnville reporting a peak gust of
81 km/h (44 kt) at both 09:37, out of 190º, and 06:47, out of 170º. Hillsboro reported
78 km/h (42 kt) out of 160º at 12:48. Rainfall in some areas has been very
heavy. Aurora, for example, reported 10.7 mm (0.42") in the hour ending
14:53.
On the coast, Hoquiam
reported 13.7 mm (0.54") in the hour ending 08:53, followed by 13.0 mm
(0.51") in the hour ending 10:53. Astoria had a whopping 16.0 mm
(0.63") in the hour ending 19:55 yesterday. This has definitely been a
juicy storm. 15:28 PST.
The peak gust at Crescent City fell short of the 98 km/h (53 kt) maximum during the 2007 event. Even a gust of 89 km/h (48 kt) at 19:05 on 19 Nov, during an earlier wave, did not quite reach the magnitude of the Great Coastal Gale. Arcata, on the other hand, did receive a higher gust during the 2012 storm, or at least matched the speed—there is some uncertainty about the maximum speed in 2007 for this station. Winds at Ukiah were not much during yesterday's event. Nor were they particularly strong at Redding an Red Bluff (not shown). 17:57 PST.
20:30 PST: The warm
sector of our recent baroclinic wave just skirted south of Victoria and
Vancouver. The warmer air did not quite reach White Rock, where the temperature
just bumped up a degree or so with the arrival of light WSW to SW winds around
19:00. Abbotsford saw the temp climb from 7ºC (45ºF) to 9ºC (48ºF) between
18:00 and 19:00 with the arrival of a light SSW to SW breeze, before falling
back to 8ºC (46ºF) by 20:00. The warm sector just barely caressed Bellingham,
with the temp jumping from 8ºC (46ºF) at 14:53 to 12ºC (54ºF) by 15:20 (27 min), accompanied by a brief period of S winds at 19 km/h gusting
35 (9 kt G 20). The temp has since fallen to about 9.5ºC (49ºF) in the most
recent observation, 19:53, accompanied by light and variable wind. Navy,
Whidbey also only received a mild shot of warm-sector air, with the temp rising
to approximately 11.5ºC (53ºF) at 14:56, accompanied by SSE winds of 31 km/h
gusting 46 (17 kt G 25). The winds had faded to WSW 19 km/h (11 kt) by 15:21,
with the temp down to 10ºC (50ºF). Gusts were stronger earlier in the storm's
history, reaching 81 km/h (44 kt) in gusts out of 140º at 00:39.
Everett, however,
received a more serious warm-sector dose. Between 12:53 and 13:32, winds leaped
from S 15 km/h (8 kt) to S 56 km/h gusting 74 (26 kt G 40) and the temperature
jumped from around 10.5ºC (51ºF) to 12ºC (54ºF). The pressure also began rising
at a good clip, from a minimum of 99.42 kPa (29.36" alt) at 12:53 to an
altimeter of 29.39" by 13:32, only to fall again, briefly, to 99.44 kPa
(29.37" alt) by 13:53, then jumping to 99.60 kPa (29.43" alt at
14:53. This double-dip likely marks the passage of the warm front first, followed
closely by the cold front.
The warm sector air
had even stronger presence south of Everett, with temperatures above 10ºC
(50ºF) persisting for many hours. In the blustery conditions that prevailed in
the warm, unstable air, Sea-Tac reported a peak gust of 57 km/h (31 kt) out of
180º at 13:53. Boeing Field in Seattle reported a gust of 65 km/h (35 kt) out of 210º at 13:19 and West Point reported a burst to 80 km/h (43 kt) out of 190º at 14:00. Olympia reported 87 km/h (47 kt) out of 180º at 10:29; likely,
some trees fell down in the vicinity.
During the heavy rain
episode, ahead of the warm front, that seemed to reach many locations in the
region, White Rock reported 5.1 mm (0.20") in the hour ending 12:00,
Bellingham 4.8 mm (0.19") in the hour ending 11:53, Everett 8.4 mm (0.33")
at 12:53, Bremerton 12.4 mm (0.49") at 06:55 and 11.9 mm (0.47") at
11:55, Sea-Tac 7.6 mm (0.30") at 13:53 and Olympia 6.1 mm (0.24") at
12:54.
My sister mentioned that her basement in Bremerton started to flood today, and that they had set up a sump pump.
Those quite intense hourly totals point toward how the flood happened.
The HPC at 00:00 UTC
placed the 99.2 kPa low over the southern interior of BC. Seems like the low
center passed right over Vancouver, clearly occluded this far north, based on
the warm-sector response described above. 21:07 PST.
 |
| Storm slowly exiting Cascadia. As of 04:30 UTC (20:30 PST), the frontal system had moved well inland over British Columbia and Washington, with the tail still lagging over Oregon. Image courtesy of the National Weather Service. |
07:47 PST: (Vancouver, BC) The
baroclinic band is still draped over Oregon, with periods of moderate to heavy
rain afflicting parts of the Willamette Valley and surrounding uplands, and
heavy snow in places at elevations above approximately 1,200 meters (4,000 ft).
Cyclogenesis is taking place along the tail end of the band, off of Southwest
Oregon. An enhanced dry slot clearly defines the area. It appears that this
developing low will likely track northeast across the Beaver State, skirting
south of the Willamette Valley. In the cooler, more unstable air behind the
band, convective showers are expected, some of which could bring strong winds
to the surface. Gusts of 80-100 km/h (40-50 kt) could occur on the coast and
55-70 km/h (30-40 kt) in the interior. Lightning strikes are being detected
offshore, in a large mass of clouds rotating around a cold upper low centered
about 46ºN 135ºW.
Up here, we have
mostly clouds sky with a broken stratus deck. Vancouver International reported
a temp of 7ºC (45ºF), dew point 5ºC (41ºF), wind E 13 km/h (7 kt) and pressure
100.28 kPa (29.61" Hg), falling 0.8 hPa/hr. 08:00 PST.
16:40 PST: A decent
shower pattern has established itself throughout much of the region. Around
14:30, a dark-based cell moved through Vancouver, bringing with it moderate
rain and gusty winds that shoved the trees in a strong sway for a few minutes.
Vancouver International reported SSE 37 km/h gusting 50 (20 kt G 27) at 14:33
along with a light rain shower. Scanning many stations, I see that Hillsboro
had a moderate rain shower that produced a gust to 70 km/h (38 kt) out of 250º
at 12:47. Only 0.5 mm (0.02") of rain fell in that hour, however.
The cyclogenesis
early this morning off of Southwest Oregon did not amount to much. Barometric
indicators barely moved in response to the dry slot moving inland.
Some more peak gusts
from yesterday's baroclinic wave, from a list compiled by Clinton Rockey of
NWS, Portland and posted at 22:30 on 19 Nov 2012:
Peak Gust 19 Nov 2012 Coastal Gale
|
|||
Location
|
Time (PST)
|
Speed (km/h) (kt)
|
|
High Elevation
Sites
|
|||
Naselle Ridge
|
09:45
|
183 (99)
|
|
Megler Tower
|
09:35
|
101 (88)
|
|
Mt Hebo
|
13:08
|
170 (92)
|
|
Well-Exposed
Coastal Sites
|
|||
Cape Disappointment
|
11:15
|
148 (80)
|
|
Columbia River Bar
|
10:00
|
156 (84)
|
|
Clatsop Spit
|
09:00
|
143 (77)
|
|
Garibaldi
|
08:55
|
135 (73)
|
|
Lincoln City
|
08:50
|
137 (74)
|
|
Yaquina Head
|
00:49
|
157 (85)
|
|
Interior Valleys
|
|||
Newberg
|
12:10
|
96 (52)
|
|
Hillsboro Airport
|
12:53
|
78 (42)
|
|
Portland Airport
|
10:00
|
63 (34)
|
|
Forest Grove
|
00:30
|
59 (32)
|
|
This does not show
everything, but is a good representative example. With any weather variable,
context is important. This is why I tend to focus on airport and other weather
stations that have well documented site characteristics and a long period of record, and I am reluctant to use isolated
readings from unknown stations. And it is why the table is broken into sections
based on exposure. Exposed ridgetops at relatively high elevation are often
favored for very high readings. Another aspect of context is comparing readings at
the same station between storms. What is the wind climatology of a given station
like? Are 100 k/h (54 kt) gusts relatively common at the site? Even higher
gusts? Though the readings at places like Naselle Ridge during the 19 Nov tempest are quite high, they are far short of the powerful gusts produced by
the Great Coastal Gale of 2007. In 2007, Naselle experienced a 225 km/h gust (122
kt) and during the great Columbus Day Storm a gust of 258 km/h (139 kt) occurred.
Coastal headlands and beach areas with a long over-water fetch are also prone
to very high readings. During the 2007 event, gusts were higher than
yesterday's storms at places like Clatsop Spit and Cape Disappointment.
Yesterday's storm
struck parts of Northern California fairly decently. Here are a few of the
reports:
Peak Gust 19 Nov 2012 Coastal Gale
California Stations
|
|||
Location
|
Time (PST)
|
Direction (º)
|
Speed (km/h) (kt)
|
Crescent City
|
06:13
|
170
|
78 (42)
|
Arcata
|
07:14
|
250
|
89 (48)
|
Ukiah
|
09:56
|
140
|
33 (18)
|
The peak gust at Crescent City fell short of the 98 km/h (53 kt) maximum during the 2007 event. Even a gust of 89 km/h (48 kt) at 19:05 on 19 Nov, during an earlier wave, did not quite reach the magnitude of the Great Coastal Gale. Arcata, on the other hand, did receive a higher gust during the 2012 storm, or at least matched the speed—there is some uncertainty about the maximum speed in 2007 for this station. Winds at Ukiah were not much during yesterday's event. Nor were they particularly strong at Redding an Red Bluff (not shown). 17:57 PST.
