An Intense Cyclone Over the Northeast Pacific Promises Some Bluster

An intense extratropical cyclone had developed over the Northeast Pacific and is now nearly stationary off the west shore of Haida Gwaii. The cyclone exhibits a dramatical-looking doubly-wound spiral, or occluded front, near the centre. The tightly wound nature of the low is an indication of a mature system. Occlusions can become quite long as they are stretched around a cyclonic centre in this manner. Water Vapour satellite mage taken at 0700 PDT 02 Apr 2012 and is courtesy of the US National Weather Service.

We had a beautiful, mostly sunny afternoon yesterday. A few showers popped up in the vicinity but nothing moved right over my neighbourhood. Under all that sunshine, the temp climbed to a relatively warm 10.9ºC (51.6ºF) at Vancouver International.

Now, a very intense low has developed in the Northeast Pacific. As of the 1200 UTC Hydrometeorological Prediction Center (HPC) surface analysis, the low center had reached 53ºN 138ºW, nearly due west of Haida Gwaii. An intense pressure gradient surrounded the core, with a central pressure of 95.6 kPa (28.23" Hg). A strong pressure gradient is also associated with the leading warm and cold frontal systems, both of which are nearing the coast of Vancouver Island. An intensifying southeast pressure slope is already over Southwest British Columbia. The frontal boundaries are moving rather slowly, and the low center even more so. In fact, the doubly-wound spiral at the storm's core is nearly stationary. The low is also vertically stacked, or mature, and has almost certainly passed peak intensity.

The deep low is the kind of extratropical cyclone that generates our big windstorms, when they track closer to the coast than the current system. Given the more distant track, the winds are not expected to reach historical proportions. Environment Canada is forecasting southeast winds climbing toward 50 to 70 km/h (27 to 38 knots) by tonight in Vancouver Metro. The US National Weather Service has a wind advisory out in the Northwest Interior, with wind gusts up to 80 km/h (43 kt) expected at places like Bellingham.

With the incoming fronts, Solander Island is reporting extreme wind speeds, but this is rather typical for the station. At 0700, winds were ESE 113 km/h (61 kt) mph gusting 143 (77). The pressure had dropped to 99.77 kPa (29.46" Hg). The Estevan Point lighthouse reported winds E 48 km/h (26 kt) gusting 80 (43) at 07:00, with a pressure of 101.16 kPa (29.87" Hg). Note the steep pressure differential between the two stations: 13.9 hPa. This reflects the strong pressure gradients around the massive low, reaching far out from the centre.

Here in Vancouver, we have low, gray skies, a gentle breeze and a somewhat mild on-patio temperature of 8.6ºC (47.5ºF) indicative of 7ºC (44.6ºF) out in the park across the street. The relative humidity is 72%, with a pressure of 30.15"—rather high and not particularly threatening. The Davis reads 102.21 kPa, actually up 0.1 hPa in the hour ending 07:45. This despite and incoming front. The sky promises rain, and the barometer sunshine. Not atypical for the area.

At the airport:

Vancouver International Observation 0700 PDT
WX/Sky	BKN028 OVC090	Vis	15.00
Wind	ESE 28 (15)	T/Td	7.7/2.2
SLP	102.19	Tdcy	-0.1
Vis mi, T/Td ºC, And km/h (kt), SLP kPa, Tdcy hPa/hr.

Even though winds in my neighborhood are somewhat light—with the mild shaking of the tree limbs, I estimate 10-15 km/h (6-8 kt) in gusts at times—wind speeds at the airport have been stronger. At 0500, SE winds reached 28 km/h (15 kt) gusting 37 (20). The temperature has been mild all night, with a low around 7.2ºC (45ºF). The thermometer at Estevan Point, by the way, indicated 8.3ºC (47ºF) at 0700, and at Solander 6.7ºC (44ºF). Both locations also showed little temperature change overnight.

Even further south, at Quillayute, the temp at 0753 is 8.3ºC (47ºF) and somewhat warmer than earlier this morning. Winds, however, are SSE and had reached 28 km/h (15 kt) gusting 48 (26) by the 0753 observation. This appears to be a response associated with warm frontal passage, which appears to have occurred around 0412 at this station based on a wind shift from SE to SSE and an acceleration of speed, accompanied by a slight warming of the temp. The cyclone's warm sector is not particularly toasty, with a temp of 8.9ºC (48ºF) being indicated by Buoy 46206 at 0700, and 46005 reporting 10ºC (50ºF) at 0150 before the cold front brought the temp down to 6.7ºC (44ºF) by 0550.

Given the relatively mild temp at Estevan Point, it appears that the warm front is at, or very near, this location. Cooler Solander is perhaps north of the triple-point.

SE to SSE winds have been fairly strong at the two above-mentioned buoys, but not at a major windstorm level. Buoy 46206 reported winds SE 55 km/h (29.5 kt) gusting 72 (39) at 0600, the highest so far, and 46005 reported 61 km/h (33 kt) gusting 76 (41) at 0150, in association with the cold front. Direction is not being reported. The sea surface temperature, by the way, is 7.7ºC (46ºF), and had likely contributed to cooling the warm sector, reducing its intensity.

Update 1507 PDT:

The beautifully wound up cyclone continues to very slowly move northward along 139ºW, and is now near 54ºN. The leading cold front has slowly progressed eastward over Vancouver Island, with the boundary now past Solander Island, and a decent stream of moisture passing over the central portion of the island. Moderate to heavy rain has been soaking Estevan Point for a number of hours now:

Time (PDT)	Rain Total (mm/hr)	Rain Total (in/hr)
1000	3.0	0.12
1100	6.6	0.26
1200	7.4	0.29
1300	5.3	0.21
1400	4.3	0.17

Wind speeds at Estevan Point have also increased markedly, with a report at 1400 of ESE 69 km/h (37 kt) gusting 93 (50), high-wind criteria speeds.

The near hurricane-force winds at Solander Island slowed dramatically after noon, when the frontal boundary arrived. Winds SSE 104 km/h (56 kt) gusting 120 (65) at 1200 became SSE 56 km/h (30 kt) by 1300, then shifted to due S at 56 km/h (30 kt) gusting 70 (38) by the end of the next hour. The pressure jumped from 99.71 kPa (29.44" Hg) at 1100 to 100.04 kPa (29.54" Hg) at noon, an hourly change of 3.3 hPa. The temp fell from 7.8ºC (46ºF) at 1100 to 6.1ºC (43ºF) by 1300.

Here in Vancouver, we have not seen any rain yet, and indeed had some sunbreaks earlier this afternoon. The temp has warmed dramatically to 13ºC (55.4ºF) as of the most recent observation at 1400. Winds, however, have slacked off from a maximum of ESE 41 km/h (22 kt) gusting 52 (28) at 1100. The latest report indicated ESE 24 km/h (13 kt). However, the pressure in the same observation indicated a 1.1 hPa fall in the past hour, down to 101.85 kPa (30.08" Hg). The barometric trend reflects the slowly approaching cold front.

Bellingham has reported a maximum gust, so far, of 54 km/h (29 kt) out of 130º at 1255, plus on two other occasions before this observation.

Some maximum gusts on the Washington coast (so far):

Location	Direction (º)	Gust (km/h & knots)	Time (PDT)
Tatoosh I	170	80 (43)	1323
Quillayute	150	67 (36)	1248
Destruction I	140	91 (49)	1015
Hoquiam	60	37 (20)	1034

Not much happening at Hoquiam, but places north are reporting gale-force gusts. 

Update 1945 PDT:

The Pacific front is crawling eastward and now has passed Estevan Point, based on recent METAR information. SE winds 65 km/h (35 kt) gusting 76 (41) at 1700 dropped to SE 24 km/h (13 kt) during the following hour, with the temperature falling from 8.3ºC (47ºF) to 7.2ºC (45ºF), changes that likely mark the passage of the front. Moderate rain also tapered off to light by 1900.

Tofino is now under the baroclinic hose, with steady moderate rain, along with mist, since noon. Winds have been strong, too, with speeds climbing to SSE 56 km/h (30 kt) gusting 70 (38) at 0900, and a SE gust to 80 km/h (43 kt) at 1100.

East winds finally shifted to south and southeast by 1453 at Hoquiam. Though speeds are not particularly strong, with a maximum gust of 25 mph out of 170º at 1653. The temp, however, climbed to a rather warm 13.9ºC (57.0ºF) at 1553. Partly sunny skies likely enhanced this warm sector temperature.

New gust maxima for the Washington coast:

Location	Dir (º)	Gust (km/h)	Gust (knots)	Time (PDT)
Tatoosh I	170º	100	54	1707
Quillayute	160º	74	40	1542
Destruction I	170º	89	48	1407

 Wind speeds appear to be tapering off in recent observations from all three of these locations, so the above values may be the peaks for this storm. The front may be weakening, along with the low. As of 1700 (0000 UTC), the HPC analyzed the cyclone's central pressure at 96.4 kPa (28.47" Hg), up nearly 1 kPa from the minimum.

Light rain recently reached Quillayute at 1853. Partly cloudy to sometimes clear skies visited the area for much of the day, with the front just offshore, carrying significant moisture into Vancouver Island.

Here in Vancouver, low, gray overcast skies dominate, with a light breeze rustling the trees. The temperature on the patio is 12.5ºC (54.5ºF), with the shade temperature away from the building likely around 11ºC (52ºF). At the airport:

Vancouver International Observation 1900 PDT
WX/Sky	BKN078 OVC085	Vis	15.00
Wind	E 20 (11) G 30 (16)	T/Td	11.1/2.8
SLP	101.28	Tdcy	-1.2
Vis mi, T/Td ºC, And km/h (kt), SLP kPa, Tdcy hPa/hr.

Winds have been easterly since 1600, and appear to be on a slow wane, with some oscillations upward, like 28 km/h (15 kt) at 1800. The temperature is also slowly dropping from 12.8ºC (55ºF) at 16:00. Looking at the satellite loop and the progress of the front, I suspect rain may reach here within a few more hours.