December 3, 2012: Monday
15:34 PST: My new
weather radio works. Environment Canada issued a wind warning for Metro
Vancouver at 10:40 this morning. When I came home, I found the red warning light on, and a
high wind warning message scrolling across the screen. Looking at the warning message online, the strongest wind are expected after
midnight. This appears to be one of those difficult-to-follow overnight storms.
The latest
satellite loops reveal a developing cyclone currently centered approximately 41ºN and 136ºW.
The system has a subtropical moisture tap and a well-developed baroclinic leaf.
The dry slot is not as enhanced as in some previous storms. Upper-level
moisture from the leading warm front is already overriding Southwest British
Columbia. Here is the latest visible satellite photo, for 23:00:
The storm is well to
our southwest. Looking at the latest WRF-GFS and MM5-NAM runs from the University of Washington, neither model
brings in a full-fledged cyclone, but instead an open wave. It looks like the
triple-point is expected to moved across central or southern Vancouver Island.
A fairly tight E to SE pressure slope is present over the Strait of Georgia
between 01:00 and 13:00 tomorrow. Looks good for 50-60 km/h (30-35 kt) over the
water and about half that over land areas. This is not 70-90 km/h as is
forecast by Environment Canada. This lowers my confidence in the high-wind
forecast for Vancouver. However, EC forecasters seem to expect the strongest winds in the SW part of the warning area, near the water. Also, a cyclone does appear to be "trying" to take shape
over the Pacific, and this frontal system certainly bears watching. The
National Weather Service, Seattle, has issued a wind advisory for the Northwest
Interior. Wind speeds of 20 to 35 mph with gusts to 50 (30 to 55 km/h with
gusts to 80). This is not too far off the EC forecast. 16:00 PST.
16:42 PST: Darkness
has largely settled over the land, with just the barest blue hint of dusk-light
visible. The heavy overcast is probably not helping. The patio thermometer reads a
rather mild 9.3ºC, with an 82% RH and a pressure of 29.86" and falling. The
wind appears light. Time to look at the 16:00 roundup:
Location | WX | Temp (ºC) | Dew Point (ºC) | Wind Spd (km/h) | SL Pres (kPa) | 1-h tendency (hPa) |
Nth Bend | OVC | 12.8 | 8.9 | 14 | 101.59 | -0.7 |
Astoria | OVC | 11.1 | 9.4 | 24 | 101.26 | -0.5 |
Hoquiam | RABR- | 11.1 | 9.4 | 24 | 101.25 | -0.4 |
Quillayute | RABR- | 8.9 | 8.3 | 8 | 101.00 | -0.9 |
Estevan Pt | RA- | 8.3 | 7.2 | 26 | 100.65 | -1.1 |
Salem | OVC | 12.8 | 6.1 | 21 | 101.54 | -0.3 |
Portland | OVC | 11.1 | 7.8 | 16 | 101.59 | -0.3 |
Olympia | RABR- | 9.4 | 8.9 | 10 | 101.38 | -0.2 |
Sea-Tac | RABR- | 8.3 | 6.7 | 14 | 101.47 | -0.4 |
Bellingham | BKN | 10.0 | 3.9 | 13 | 101.33 | -0.6 |
Abbotsford | OVC | 7.8 | 5.0 | 11 | 101.34 | 0.0 |
Vancouver | SHRA- | 7.8 | 6.1 | 24 | 101.26 | -0.9 |
Victoria | OVC | 8.9 | 7.2 | 26 | 101.19 | -0.8 |
Comox | SHRA- | 7.8 | 6.1 | 34 | 100.96 | -1.3 |
Port Hardy | SHRA- | 7.2 | 3.9 | 26 | 100.42 | -1.4 |
Average | 9.6 | 7.0 | 19.4 | 101.22 | -0.65 | |
3-hr Chg | ||||||
High | 12.8 | 9.4 | 33.8 | 101.59 | 0.0 | |
Low | 7.2 | 3.9 | 8.1 | 100.42 | -1.4 | |
Spread | 5.6 | 5.6 | 25.8 | 1.17 | 1.4 |
Rather mild
conditions exist over Oregon, with temperatures up to 13ºC (55ºF) at Salem.
Further north, where light rain and showers are occurring, the temp is a bit
depressed, with the reading of Sea-Tac, 8.5ºC (47ºF), representative. The
temperature spread between these stations is a rather modest 5.6ºC (10ºF). Precipitation
is currently confined to British Columbia and Washington stations in the list.
The barometric pressure is falling most rapidly over the British Columbia
section, supporting a track over Vancouver Island. The maximum gradient between
any one of the listed locations is 1.17 kPa (11.7 mb), not super-steep. The
average wind speed for all these stations, 19.4 km/h (10 kt) is a reflection of
this. Interestingly, winds in the Georgia Strait are already blowing rather
briskly, with gusts to 50 km/h (27 kt) at Comox, a reflection of a fairly
strong SE pressure slope already in place over SW British Columbia. (Note that there is no info in the 3-hr change row because this is the first 3-hr roundup I have taken for this event.) 17:34 PST. The temp spread
compared to 16:00 has diminished, in part because Salem has cooled off a tad.
Over
the past 3-hr, the average barometric pressure for the above stations has
dropped by 0.26 kPa (2.6 mb) and the steepest gradient between any of the
stations—in this case North Bend to Port Hardy—has now reached 1.31 kPa (13.1
mb). The 1-hr downward tendency in pressure has increased by 0.4 hPa. The
average wind speed among the locations in the table has risen slightly to 20
km/h (11 kt). Indications are pointing toward a deepening and fast-moving
system—this is supported by satellite interpretation. Just look at that large
area of enhanced clouds (beautiful):
19:00 PST: A steady
light rain falls outside, with the temperature on the patio at 9.2ºC. The
pressure is now down to 29.82" (101.00 kPa). The satellite loop reveals
quite a fast-moving storm on a steady northeast track. The 00:00 UTC HPC
surface analysis placed the then 99.7 kPa low at about 42ºN and 135ºW.
Now for the 19:00
roundup:
Location | WX | Temp (ºC) | Dew Point (ºC) | Wind Dir | Wind Spd (km/h) | SL Pres (kPa) | 1-h tendency (hPa) |
Nth Bend | MM | 11.1 | 8.9 | SSE | 10 | 101.22 | -3.7 |
Astoria | OVC | 10.6 | 8.9 | SSE | 13 | 101.04 | -0.9 |
Hoquiam | RABR- | 10.6 | 9.4 | SSE | 24 | 101.02 | -0.8 |
Quillayute | BR | 10.6 | 10.0 | SSE | 19 | 100.71 | -1.3 |
Estevan Pt | RA- | 9.4 | 9.4 | ESE | 32 | 100.23 | -1.5 |
Salem | OVC | 11.1 | 6.1 | SE | 8 | 101.19 | -1.6 |
Portland | BKN | 10.0 | 7.2 | ESE | 21 | 101.31 | -1.1 |
Olympia | RA- | 9.4 | 7.8 | S | 16 | 101.17 | -0.7 |
Sea-Tac | OVC | 8.9 | 6.1 | ESE | 16 | 101.25 | -0.9 |
Bellingham | OVC | 11.1 | 5.0 | SE | 24 | 101.33 | -0.6 |
Abbotsford | RA- | 7.2 | 5.0 | E | 10 | 101.12 | -0.5 |
Vancouver | SHRA- | 7.2 | 5.0 | E | 19 | 101.07 | 0.0 |
Victoria | RA- | 8.9 | 7.8 | SSE | 13 | 100.98 | -0.8 |
Comox | RA- | 7.8 | 7.2 | SE | 48 | 100.65 | -1.0 |
Port Hardy | OVC | 7.2 | 3.9 | ESE | 27 | 100.02 | -1.2 |
Average | 9.4 | 7.2 | 20.1 | 100.95 | -1.11 | ||
3-hr Chg | -0.27 | 0.33 | 0.4 | -0.26 | -0.41 | ||
High | 11.1 | 10.0 | 48.3 | 101.33 | 0.0 | ||
Low | 7.2 | 3.9 | 8.1 | 100.02 | -3.7 | ||
Spread | 3.9 | 6.1 | 40.3 | 1.31 | 3.7 |
The barometric
pressure has begun to plunge at North Bend, perhaps a reflection of an
intensifying wave and the approaching leading warm front. Pressure tendencies
over much of the area have picked up considerably, save for around Vancouver. South
winds arrived at Quillayute around 17:44, accompanied by intensifying rain and
a rise in temperature to 11ºC (52ºF) by 18:27. Estevan Point has also seen an
increase in temperature over the past three hours, by 1ºC (~2ºF). Winds appear
to be escalating there, with gusts to 56 km/h (30 kt). Some of that warmer air
to the south is heading northward. ESE to SE winds have picked up at Bellingham
just recently, with gusts up to 44 km/h (24 kt) around 18:51. The temperature is
rising in response to this, likely from some downsloping off of the Cascades
(look at the T-Td spread). Winds continue to escalate at Comox, marked by an
observation at 18:40 of SE 52 km/h gusting 61 (28 kt G 33).
22:00 PST: Steady light
rain continues outside. Winds remain rather light here. The patio temp is 9.1ºC
with an 83% RH and the pressure is 29.68" (100.51 kPa), falling at a good clip.
The 03:00 UTC HPC
surface analysis placed the low center near 44ºN 132ºW, still mostly an open
wave but with a hint of an occlusion. The leading warm front had not yet
reached the Pacific coast and indeed remained over 100 km off the California
coast. The water vapor satellite loop shows a strong dry slot just now reaching
130ºW with just the beginnings of a wraparound band evident. Cyclogenesis appears
to be progressing at a steady clip. And the low remains on a NE track.
Now for the 22:00
roundup:
Location | WX | Temp (ºC) | Dew Point (ºC) | Wind Dir | Wind Spd (km/h) | SL Pres (kPa) | 1-h tendency (hPa) |
Nth Bend | RA- | 8.9 | 7.8 | SE | 13 | 100.78 | -4.4 |
Astoria | RA- | 9.4 | 8.3 | ESE | 10 | 100.54 | -1.3 |
Hoquiam | RA- | 9.4 | 8.9 | E | 21 | 100.58 | -1.3 |
Quillayute | RABR | 10.0 | 8.9 | SSE | 24 | 100.23 | -1.8 |
Estevan Pt | RA- | 10.0 | 10.0 | ESE | 58 | 99.68 | -1.9 |
Salem | RA- | 10.6 | 5.6 | SSE | 11 | 100.82 | -1.0 |
Portland | OVC | 10.0 | 7.2 | ESE | 21 | 100.78 | -1.6 |
Olympia | OVC | 8.3 | 7.2 | W | 5 | 100.70 | -1.6 |
Sea-Tac | OVC | 8.9 | 5.0 | E | 10 | 100.80 | -1.9 |
Bellingham | OVC | 11.1 | 5.6 | SE | 24 | 100.65 | -1.9 |
Abbotsford | RA- | 6.1 | 5.0 | NNE | 13 | 100.83 | -1.8 |
Vancouver | SHRA- | 7.2 | 6.1 | E | 27 | 100.60 | -1.7 |
Victoria | OVC | 8.9 | 7.8 | SE | 27 | 100.44 | -2.0 |
Comox | RA- | 7.8 | 7.2 | SE | 42 | 100.16 | -1.6 |
Port Hardy | SHRA- | 6.1 | 5.0 | ESE | 27 | 99.50 | -1.1 |
Average | 8.9 | 7.0 | 22.2 | 100.47 | -1.79 | ||
3-hr Chg | -0.27 | 0.33 | 0.4 | -0.26 | -0.41 | ||
High | 11.1 | 10.0 | 58.0 | 100.83 | -1.0 | ||
Low | 6.1 | 5.0 | 4.8 | 99.50 | -4.4 | ||
Spread | 5.0 | 5.0 | 53.1 | 1.33 | 3.4 |
On the coast, wind
has gone offshore, strongly so at Astoria and Hoquiam, a classic pattern for an
incoming strong extratropical cyclone. E to ENE at Hoquiam is the typical
direction for a storm moving in out of the southwest. Heavy rain has arrived in
Quillayute with 6.9 mm (0.27") in the hour ending 21:53. Pressure is
falling fast up and down the coast, with the largest changes in the north
section and at North Bend. (We just had a brief 1-sec power outage here—and the
storm is just barely getting started—22:22—and now we had another.) The
strongest pressure falls are concentrated from Estevan Point down to Sea-Tac
and then at North Bend. Again, I take the North Bend response to be influenced
by the deepening low just offshore and the approaching frontal bands. Like some
of the coastal stations, winds have swung offshore at Sea-Tac and Portland as
well. SE winds at Bellingham are continuing strong, but show no significant
escalation since 19:00. In stark contrast, Abbotsford has light NNE winds, which
are bringing significantly cooler air into the area—not very far from
Bellingham. East winds at Vancouver have reached their highest level yet this
hour and SE winds at Victoria are up a notch. Comox reported a SE gust to 67
km/h (36 kt) at 21:25.
At -1.79 hPa/hr, the
average hourly pressure declension (for the 15 stations) is very close to that
achieved by the powerful March 12, 2012 windstorm (-2.03 hPa/hr at its most
extreme). But the pressure changes have been so uniform over the region that
the maximum pressure gradient between the stations is only up slightly at 1.33
kPa (13.3 mb). The average wind speed, however, has climbed to 22 km/h (12 kt),
mainly due to increases at the northern stations. Temperatures overall are
cooling, largely a reflection of strengthening offshore winds. 22:46 PST.
December 4, 2012: Tuesday
06:45 PST: (Vancouver, BC) The wave
occluded and largely shot due north, with the 97.9 kPa low center near Haida Gwaii at 04:00 PST. The cyclone did not become that well-defined on isobaric maps
and seemed stuck in an open-wave arrangement. The cloud mass, dry slot and all
moved well inland overnight. The end result: Fizzle. At least for the high wind
potential in Vancouver Metro. Looking at the last two 3-hourly roundups, with 01:00 PST first:
Location | WX | Temp (ºC) | Dew Point (ºC) | Wind Dir | Wind Spd (km/h) | SL Pres (kPa) | 1-h tendency (hPa) |
Nth Bend | MM | 12.8 | 11.1 | S | 35 | 100.58 | -2.7 |
Astoria | RABR- | 8.3 | 6.7 | ESE | 16 | 99.88 | -0.9 |
Hoquiam | RABR- | 8.9 | 7.2 | E | 29 | 99.87 | -3.1 |
Quillayute | RABR | 7.8 | 6.1 | SE | 26 | 99.61 | -2.7 |
Estevan Pt | RA | 9.4 | 8.9 | ESE | 58 | 99.05 | -2.0 |
Salem | RA | 8.9 | 7.8 | S | 24 | 100.23 | -1.9 |
Portland | RA | 8.9 | 7.8 | ESE | 21 | 100.34 | -1.9 |
Olympia | RABR | 8.3 | 6.7 | S | 13 | 100.14 | -2.4 |
Sea-Tac | RA | 8.3 | 5.6 | E | 13 | 100.33 | -1.2 |
Bellingham | RA- | 11.7 | 5.0 | SE | 24 | 100.17 | -1.3 |
Abbotsford | RA- | 6.1 | 5.0 | NNE | 8 | 100.20 | -1.6 |
Vancouver | RA- | 7.2 | 6.1 | E | 34 | 100.06 | -1.6 |
Victoria | RA- | 8.9 | 7.2 | SE | 34 | 99.93 | -1.9 |
Comox | RA- | 7.8 | 7.8 | SE | 47 | 99.57 | -2.1 |
Port Hardy | SHRA- | 7.2 | 5.0 | ESE | 19 | 98.83 | -2.6 |
Average | 8.7 | 6.9 | 26.7 | 99.92 | -1.99 | ||
3-hr Chg | -0.27 | 0.33 | 0.4 | -0.26 | -0.41 | ||
High | 12.8 | 11.1 | 58.0 | 100.58 | -0.9 | ||
Low | 6.1 | 5.0 | 8.1 | 98.83 | -3.1 | ||
Spread | 6.7 | 6.1 | 49.9 | 1.75 | 2.2 |
North
Bend data stopped transmitting at 00:15: This is the observation in the above
table. Looks like the warm front had just reached this location, with the temp
well up and a strong S breeze. Hoquiam and Astoria still had a good offshore
breeze going. Downward pressure tendencies on the coast were quite strong at
this time, just head of the incoming front and passing wave. Estevan Point
reported a gust to 81 km/h (44 kt) at 23:00. The apparent warm front neared
Salem by this time, with winds becoming strong from the S and the temp
beginning to rise. Plus, moderate rain to the tune of 5.6 mm (0.22") fell in
the hour ending 00:56. Portland also had a decent soaker with 4.6 mm
(0.18") in the same hour and Olympia had the same amount. Sea-Tac would
end up with 4.8 mm (0.19") in the hour ending 01:53. With strong SE winds
blowing up the Georgia Strait, Comox reported a gust to 70 km/h (38 kt) at
midnight. Winds were beginning to slow at Port Hardy by 01:00.
And at 04:00 PST:
Location | WX | Temp (ºC) | Dew Point (ºC) | Wind Dir | Wind Spd (km/h) | SL Pres (kPa) | 1-h tendency (hPa) |
Nth Bend | MM | 13.3 | M | S | 71 | 100.67 | 0.9 |
Astoria | RABR- | 12.2 | 11.7 | SW | 37 | 100.21 | 2.0 |
Hoquiam | BR | 11.7 | 10.6 | SSW | 39 | 100.17 | 1.3 |
Quillayute | RABR- | 9.4 | 8.9 | S | 26 | 99.50 | 1.9 |
Estevan Pt | RA+ | 8.3 | 7.8 | SSE | 50 | 99.02 | 2.0 |
Salem | BR | 11.1 | 10.6 | S | 27 | 100.52 | 0.8 |
Portland | OVC | 11.7 | 10.0 | SSE | 11 | 100.51 | 1.1 |
Olympia | OVC | 8.9 | 7.2 | SSW | 21 | 100.07 | -0.2 |
Sea-Tac | RABR- | 7.8 | 6.1 | SE | 13 | 100.07 | -0.2 |
Bellingham | OVC | 6.7 | 5.6 | NNE | 8 | 99.83 | -1.1 |
Abbotsford | RA- | 6.1 | 5.0 | ESE | 5 | 99.84 | -1.1 |
Vancouver | RA- | 7.2 | 6.1 | ESE | 34 | 99.73 | -0.8 |
Victoria | RA- | 7.8 | 6.1 | SE | 34 | 99.63 | -0.3 |
Comox | RA- | 7.8 | 7.8 | SE | 52 | 99.19 | -0.8 |
Port Hardy | SHRA- | 5.0 | 3.9 | W | 11 | 98.73 | 1.3 |
Average | 9.0 | 7.7 | 29.2 | 99.85 | 0.45 | ||
3-hr Chg | -0.27 | 0.33 | 0.4 | -0.26 | -0.41 | ||
High | 13.3 | 11.7 | 70.9 | 100.67 | 2.0 | ||
Low | 5.0 | 3.9 | 4.8 | 98.73 | -1.1 | ||
Spread | 8.3 | 7.8 | 66.0 | 1.94 | 3.1 |
North Bend data is
from Cape Arago, a spot favored for high wind readings. Gusts reached 128 km/h
(69 kt) at 02:57. A warm front appears to have reached Astoria by 01:55, with
the temp jumping from 8ºC (46ºF) at 01:21 to 11ºC (52ºF) by 01:55 and 12ºC
(54ºF) by 02:06, accompanied by strong S winds. These winds then shifted to SSW
by 02:23 and SW by 03:47. Peak gust 83 km/h (45 kt) out of 210º at 02:28. The
warm front reached Hoquiam by 03:23, with winds shifting from E 19 km/h (10 kt)
at 03:23 to S 35 km/h gusting 48 (19 kt G 26). The temp jumped from 8.5ºC
(47ºF) to 12ºC (54ºF) in that timeframe. Hoquiam's peak gust: 65 km/h (35 kt)
out of 200º at 03:52. The warm-frontal arrival at Quillayute occurred just
after 04:00, with winds shifting from SSE to S, then SSW and the temp climbing
to 11ºC (52ºF) by 04:33. Low pressure occurred at 02:55 with a reading of 99.31
kPa (29.32" alt). The frontal boundary, possibly occluded this far north,
had reached Estevan Point by about 04:00, marked by a wind shift to SSE—SW at
05:00—and diminishing winds. Plus a round of heavy rain with 6.6 mm
(0.26") in the hour ending 04:00. Peak gust: ESE 91 km/h (59 kt) at 03:00,
just shy of high wind criteria; however a maximum wind of SE 67 km/h (36 kt) at
23:00 just edged into high-wind category.
At Salem, brief heavy rain along with
the strongest S winds occurred right around 02:00, clearly marking frontal
passage. Peak gust 61 km/h (33 kt) out of 190º at 01:51. Only a modest breeze
hit Portland at the time of frontal passage. The front had just reached Olympia
at this time and the reported pressure for this station is the storm minimum.
The same is true of Sea-Tac, and both stations had the same pressure reading
for both hours. Quite interestingly at Bellingham, after a period of light rain
that ended after 02:53, the wind shifted to light NNE to NE for a time,
bringing with it much cooler air from out of the Fraser Valley and the temp
plunged to 6.5ºC (44ºF) by 03:53, from 12.5ºC (53ºF) at 00:53. After this,
pressure minimum occurred at 04:53 with a reading of 99.77 kPa (29.44"
alt) and strong SSE winds arrived, bringing back the warmer air. All this
information points to a passing warm occluded front. Peak gust at Bellingham 63
km/h (39 kt) out of 140º at 05:50. Abbotsford has remained under the influence
of NNE to NE winds and a shielding (from strong south winds) cold surface
layer.
Unlike Bellingham, Vancouver had a decent period of steady light rain
from this front, lasting from 23:00 to 05:00. Low pressure occurred at 05:00
with a reading of 99.69 kPa (29.44" Hg). Winds have shifted to SE as of
07:00, with gusts to 41 km/h (22 kt), accompanied by a temperature rise to 9ºC
(48ºF)—with the wind shift and temp increase post-rainfall, this also suggests
a warm occlusion. A strong SE breeze blew all night at Victoria. A maximum gust
of SSE 61 km/h (33 kt) occurred at 05:00, just after pressure minimum. Winds
became SW, with a speed of 33 km/h gusting 46 (18 kt G 25) by 07:16 and the
temp climbed to 11ºC (52ºF). The front had moved through. At Comox, pressure
minimum of 99.11 kPa (29.26") occurred at 05:00, and maximum winds
followed shortly thereafter with a speed of SE 59 km/h gusting 89 (32 kt G 42)
at 06:00. By 07:28, the precipitation had stopped and winds had slowed to S 17
km/h (9 kt). The front passed through Port Hardy between 03:00 and 04:00, with
the ESE winds shutting down and becoming light westerly. Pressure minimum of
98.60 kPa (29.15" Hg) occurred at 03:00. Pressure is now rising rapidly,
with a jump from 99.17 kPa to 07:00 to 99.41 kPa at 08:00. Pressure tendencies
at Comox are similar.
The storm has clearly
moved through much of the region, and it appears any high wind threat for
Vancouver and surrounds is now over. With a peak gust of E 46 km/h (25 kt) at
Vancouver International around 05:40, winds did not come close to the forecast.
It looks like the Oregon coast received the brunt of the winds.
The satellite photo
loops reveal that another wave has developed on the baroclinic band. This
feature appears to be targeting Oregon. 08:24 PST.
08:35 PST: We are now
getting some strong WSW winds, whistling around the window frames and producing
some readings on the patio-locked anemometer: 1.8 km/h. Onshore flow has arrived in earnest. The sun paints a
beautiful yellow light on Tisdall Park. The sky is a clean powder blue. The storm has passed. 08:36
PST.
Very nice analysis!
ReplyDeleteThank you much. This kind of reporting takes much effort. Good to get some positive feedback.
Delete