Volume 56, Number 3 December 2012 Photo by Denice Drass

North pacific Area
December 2012 ~ Mariners Weather Log
38
introduction
OBSERVATION POSITION DATE/TIME (UTC) WIND SEA(m/f)
Overseas Joyce (V7NV4) 37N 147E
38N 149E
The most active storm track during
the period was from the western
North Pacific Northeastward, with
the cyclones passing near or south
of the Aleutian Islands on their way
toward the Gulf of Alaska with some
originating in the central or eastern
waters before tracking northeast
toward the Canadian coast or Southeast
Alaska. A blocking pattern in early
April forced two intense cyclones
near Japan to instead turn north into
the Sea of Okhotsk where they stalled
and weakened. In a continuation
of the active pattern of the previous
two months, ten cyclones developed
hurricane force winds in January. The
three hurricane force events of April
occurred early in the month with one
producing the highest winds seen in
scatterometer data during the six month
period, near Japan. The only hurricane
force low to occur during May and June
had tropical origins (Typhoon Mawar
early in June). Mawar was one of three
tropical systems to re-curve into the
mid latitude westerly’s off Japan before
becoming extratropical during late May
and June.
Tropical Activity
11/1800
12/0000
Typhoon Sanvu. Sanvu moved
northwest to appear on OPC’s
radiofacsimile analysis charts late on
May 22, passing near 17N 140E at 0600
UTC on the 23 rd as an intensifying
tropical storm with maximum sustained
winds of 55 kts. Sanvu became a
typhoon at 1800 UTC on the 23 rd and
reached maximum strength near 22N
139E with sustained 80 kts winds while
beginning a turn to the northeast into
the mid latitude westerly’s. The cyclone
then slowly weakened, becoming a
strong tropical storm at 1800 UTC on
the 26 th while passing near 26N 1144E.
Sanvu then merged with the southwest
end of a trailing frontal zone and
became a post tropical gale force low
near 29N 149E at 1200 UTC on the 27 th .
At that time the Ever Divine (9V7956)
to the north near 32N 149E reported
northeast winds of 40 kts and 9.0 meter
seas (30 feet). The remains of Sanvu
then moved northeast and dissipated
near 35N 165E early on May 30.
Typhoon Mawar: Northeastward
moving Mawar passed south of Japan
near 29N 135E as a weakening typhoon
NW 50
NW 50
MOL Innovation (9VVP) 46N 153E 12/1200 W 50
Hanjin Philadelphia (A8CN8) 53N 174E
55N 178E
Othello (SBLW)
SHIP
SHIP
47N 154E
56N 166E
56N 164E
12/1800
13/0600
12/1800
12/1800
14/0000
Buoy 46070 55.1N 175.3E 13/0100
Buoy 46072 51.7N 172.2W
13/0200
13/2100
14/0100
SE 50
SE 45
S 50
NE 55
SE 39 G49
Peak gust 52
Maximum
SE 35 G45
Peak gust 49
Maximum
Table 1. Selected ship and buoy observations taken during Northwestern Pacific Storm, January 11-14.
9.8/32
8.2/27
7.9/26
8.5/28
6.5/21
6.5/21
9/0/30
10.5/34
7.5/25
8.5/28
with maximum sustained winds of
65 kts 1200 UTC June 5. Mawar
weakened to a tropical storm six hours
later before transitioning into an intense
post tropical low with hurricane force
winds and frontal features as depicted
in Figure 1. The London Express
(DPLE) near 33N 136E reported
northeast winds of 55 kts at 1800 UTC
on the 5 th when Mawar was still a
tropical storm. The infrared satellite
image in Figure 2 shows Mawar near
maximum intensity as a post tropical
low. It displays the cloud features
found in an extratropical low such a
comma head and tail (occlusion and
trailing front) but also a semicircular
central dense cloud feature around the
north side of a partial eye like feature
near 40N 151E as Post tropical Mawar
retains some tropical like features.
Figure 3 is a 25 km OSCAT image of
winds around Mawar about thirteen
hours after it became post tropical. The
strongest winds still appear in close to
the center, a tropical like feature. There
are 70 kts wind appearing among
data that is not rain flagged (white).
Post tropical Mawar then moved east
northeast and began to weaken with its
top winds lowering to storm force 0600