Marine Weather Review – North Pacific Area January to April 2009

By George P. Bancroft NOAA National Center for Environmental Prediction

Introduction

The weather pattern over the North Pacific became increasingly active for extratropical cyclones as the winter season progressed and remained quite active through March. The most active storm track ran from near Japan northeast toward the Aleutians and Bering Sea with the strongest systems staying east of the Kurile Islands and Kamchatka Peninsula. There was occasional movement or redevelopment of cyclones toward the Gulf of Alaska. When the eastern Pacific high pressure area shifted west toward midocean low pressure could develop off California and move east or northeast, with the strongest of these occurring early in March. Unlike early in the winter season and fall 2008 there was a lack of hurricane force activity east of 160W, with most of these occurring in the western North Pacific. The number of hurricane force lows in January was four, up from only three in December 2008. The numbers increased to seven and six in February and March, respectively, and dropped to two in April. In a study done for the period October 2001 to April 2004 hurricane force cyclones were found to have the highest frequency in December in the North Pacific (Reference 1), rather than later in the winter during this past winter season.

There was no tropical activity in the North Pacific during January to April 2008. Concern lies mainly with tropical cyclones coming from the tropical western Pacific and appearing on OPC’s oceanic analysis charts. This period is normally the least active of the three four-month periods covering a year of activity. There was some tropical activity, but well southwest of the area (Reference 2).

Significant Events of the Period

Westerm North Pacific Storm, December 30, 2008 to January 3, 2009: The month of January began with a hurricane force cyclone which originated near Japan in late December and developed as depicted in Figure 1. The storm is shown at maximum intensity in the second part of Figure 1. At 0600 UTC December 31 the buoy 41929 (32N 150E) reported northwest winds of 55 kts. At 0000 UTC January 1 a ship reporting with the callsign SHIP (35N 167E) encountered northwest winds of 45 kts and seas 11.5 m (37 ft). Later, the ship C6UB2 (36N 170E) reported west winds of 40 kts and seas 10.5 m (35 ft) at 1800 UTC on the 3rd. A high resolution QuikSCAT scatterometer pass from 1851 UTC on December 31 showed the west side of the cyclone with winds to 65 kts. The cyclone was one of the deepest (in terms of central pressure) to occur in the North Pacific during the four-month period. The system subsequently turned northwest and began to weaken with its maximum winds lowering to storm force on the morning of January 1, and then to gale force as the cyclone looped back to the southwest and then southeast to a position near 44N 163E by 0600 UTC on the 3rd. The cyclone later dissipated as it merged with a stationary front just south of the central Aleutian Islands early on the 5th.

Western North Pacific Storm, January 9-14: Figure 2 displays the development of this major cyclone from a frontal wave of low pressure over a twenty-four hour period. The central pressure fell 32 hPa in this period, with the cyclone developing winds to 65 kts on the south side (Figure 3) and also in the easterly flow north and northeast of the cyclone. Table 1 lists some ship reports including those with winds approaching hurricane force. The cyclone developed a central pressure of 968 hPa near 42N 149E at 1800 UTC on the 10th near the time of the scatterometer pass in Figure 3. Afterwards the system elongated northeast with its winds dropping to storm force the next day, and the system with an expanded circulation developed a lowest central pressure of 957 hPa near 45N 178E at 1800 UTC on the 12th. The peak intensity of this cyclone (in terms of central pressure) followed the time of maximum winds by about two days. Late on the 13th the cyclone weakened, becoming a large gale near 49N 170W which late on the 15th became absorbed by a developing cyclone on a front to the southeast.

South-central North Pacific Storm, January 10-11: The 1004 hPa frontal wave of low pressure appearing near 32N 173W in Figure 2 developed into a compact hurricane force low by 0000 UTC on the 11th with the center passing near 38N 163W with lowest central pressure of 982 hPa six hours later. There was a drop in pressure of 22 hPa in the twenty-four period ending at 0600 UTC on the 11th. This is a respectable rate of intensification for that southern latitude. The cyclone developed a compact circulation, intensity and winds similar to the January 30-31 event to the north to be described next. Hurricane force winds lasted until early on January 11 after which the cyclone weakened while tracking northeast and became absorbed into the circulation of the larger western Pacific system described above.

North Pacific Storm, January 30-31: The development of this relatively compact cyclone over thirty-six hours is depicted in Figure 4. It originated as a "triple point" development, or the point where the occluded front from the parent low, the cold front and warm front meet. The second part of Figure 4 shows the storm at maximum intensity with a compact circulation.

A high resolution scatterometer pass (Figure 5) later indicated this cyclone briefly developed hurricane force winds in a small area southwest of the center. There is a 70 kts wind barb in that area. The cyclone subsequently elongated northeastward toward the Gulf of Alaska and dissipated near the Alaskan coast late on February 2.

Table 1. Selected ship and buoy observations taken during the storm of January 9-13, 2009 in the western North Pacific.
Observation Position Date/Time (UTC) Wind Seas (m/ft)
DBUQ 43N 150E 50N 173E 11/0000 13/1800 NE 60 N 45 8.0/26
WECH 41N 151E 11/0000 SW 35 9.5/31
3FXN9 41N 165E 11/0000 SE 60 13.0/42
DHER 40N 144E 11/0600 NW 55 8.0/27
OZSH2 35N 157E 11/1200 W 35 10.0/32
World Spirit (ELWG7) 43N 168E 12/1200 SE 50 10.0/33
DDYZ2 54N 178E 13/0000 E 60 9.5/31
Buoy 46071 51.2N 178.9E 12/2300 NE 40 8.5/28
OPC North Pacific Surface Analysis charts OPC North Pacific Surface Analysis charts

Figure 1. OPC North Pacific Surface Analysis charts (Part 2 - west) valid 1800 UTC December 30, 2008 and 0600 UTC January 1, 2009. (Click to enlarge)

OPC North Pacific Surface Analysis charts OPC North Pacific Surface Analysis charts

Figure 2. OPC North Pacific Surface Analysis charts (Part 2) valid 0600 UTC January 9 and 10, 2009. (Click to enlarge)

Table 2. Ship and buoy observations taken during the passage of the western North Pacific and Bering Sea storm of January 30 to February 5, 2009.
Observation Position Date/Time (UTC) Wind Seas (m/ft)
DPBJ 38N 135E
39N 136E
45N 149E
46N 152E
31/0800
31/1200
02/0000
02/0800
N 45
N 40
NW 40
NW 45
6.5/22
10.0/33
9.0/30
11.5/37
A8DE2 33N 135E 31/1200 N 65
DBUQ 37N 142E 31/1800 N 50
WDD6040 41N 164E 01/0600 S 45
SHIP 35N 165E 01/1800 W 65
OXQP2 43N 147E 01/1800 N 45 5.0/16
DDYZ2 50N 158E
48N 154E
01/2000
02/0700
NE 55
NW 55
APL Philippines (WCX8884) 43N 147E 01/2300 NW 50 8.0/26
A8OZ4 47N 153E 02/0600 NW 60 14.0/46
PECS 55N 166E 02/1200 E 45
3FFJ7 55N 163E 02/1800 N 40 10.5/35
DEGL 55N 162E 03/0300 N 55 10.5/35
Buoy 46071 51.2N 179E 02/1100
02/1400
SE 40 6.5/21
Maximum 8.0/26
Buoy 46070 55N 175.3E 02/1100 E 40
Buoy 46035 57N 177.7W 02/2300 E 40 4.5/15
Maximum 6.0/20

Table 3. Ship and buoy observations taken during the passage of the storm of February 5-8, 2009 in the western North Pacific.
Observation Position Date/Time (UTC) Wind Seas (m/ft)
V7EI5 31N 168W 06/1200 SE 45 4.0/13
SHIP 35N 156W 07/0000 W 40 8.0/26
A8CN7 35N 159E
34N 162E
07/0000
07/1200
W 45
NW 40
8.0/27
8.0/27
9VDD3 41N 159E 07/0000 N 40 8.0/27
SHIP 38N 168E 07/1200 SW 45 8.5/28
Zim USA (4XFO) 54N 163E 08/0600 NE 50 6.5/21
Buoy 46071 51.2N 179.0E 08/0100
08/0300
E 40 6.0/20
7.0/23
High resolution QuikSCAT scatterometer image of satellite-sensed winds

Figure 3. High resolution QuikSCAT scatterometer image of satellite sensed winds around the south side of the storm shown in the second part of Figure 2. The resolution is 12.5 km, versus 25 km in the coarser resolution version of QuikSCAT imagery. The valid time of the pass is 1930 UTC January 10, 2009, or thirteen and one half hours later than the valid time of the second part of Figure 2. The center of the storm was near 42N 149E at that time, just off the upper right corner of the image. Image is courtesy of NOAA/NESDIS/ Office of Research and Applications(Click to enlarge)

Western North Pacific and Bering Sea Storm of January 30-February 5: The development of this most intense cyclone of the January to April period in the North Pacific is depicted in Figure 6. Prior to this time the storm originated as a frontal wave of low pressure just south of Japan early on January 30. The central pressure fell 30 hPa in the twenty-four hour period ending at 1200 UTC on the 1st. The second part of Figure 6 shows the cyclone near maximum intensity with the actual lowest pressure of 943 hPa following six hours later. Figure 7 is a high resolution QuikSCAT image of the storm when it was off the coast of Japan. The strongest winds with this storm occurred near this time when it was more compact and over warmer water, more than two days prior to the time of maximum intensity. There are numerous wind barbs in the 55 to 70 kts range with a possible 80 kts near 40N. The second part of Figure 6 shows ships reporting 50 to 60 kts near the central Kurile Islands. As the cyclone slowed in its rate of strengthening it developed a large circulation with OPC analyzing it as a storm force low by 1200 UTC February 2. The cyclone did briefly redevelop hurricane force winds in the northwest Bering Sea ahead of the occlusion as it approached the Russian coast late on the 3rd. The system otherwise gradually weakened while moving northeast across the Bering Sea before dissipating over southwest mainland Alaska by the 7th. Table 2 below lists selected ship and buoy observations taken in this storm.

Western North Pacific Storm, February 5-8: The next major development is shown in Figure 8 as a low originating from southeast of Japan near 32N late on the 4th underwent rapid intensification. The central pressure dropped 30 hPa in the twenty-four hour period ending at 0600 UTC on the 7th. Figure 9 is a high resolution scatterometer image taken when the cyclone was still relatively far south and intensifying. Storm force winds appear around the low center including a swath of northwest winds 50 to 70 kts southwest and west of the cyclone. What appear to be conflicting wind directions on the immediate west side may indicate the wind retrievals may be unreliable. The storm subsequently turned north and maintained hurricane force winds until early on the 7th, with the lowest central pressure of 960 hPa occurring later, when the center was near the western Aleutians late on the 7th. The cyclone then turned west and weakened, with dissipation occurring near the southern Kamchatka Peninsula late on the 9th. Table 3 lists selected ships reporting higher conditions in this storm. There was only one report of storm force but several reports of seas above 8m (25 ft).

North Pacific and Bering Sea Storm, February 10-14: The movement of the next major system as a hurricane force low is depicted in Figure 10. Initial intensification was over a thirty-six period from when the cyclone originated near Japan as a 1002 hPa low late on the 9th. Scatterometer winds available near the time of the first part of Figure 10 were similar to those in the previous event (Figure 9). A later QuikSCAT high resolution pass from when the system was passing through the central Bering Sea is shown in Figure 11. Hurricane force winds of up to 70 kts appear south of the center near the central Aleutian Islands. The APL Korea (56N 180W) encountered northwest winds of 55 kts and seas 7.5 m (24 ft) at 1000 UTC on the 13th. At 0100 UTC February 13 the buoy 46071 (51.3N 179.2E) reported west winds of 45 kts and seas 12.0 m (39 ft). The Bering Sea buoy 46035 (57.1N 177.8W) reported northwest winds of 35 kts and seas 6.0 m (20 ft). The cyclone subsequently continued on a northeastward track and weakened upon moving inland over western Alaska on the 14th.

Table 4. Ship observations taken during the passage of the storm of February 20-22, 2009 in the western North Pacific.
Observation Position Date/Time (UTC) Wind Seas (m/ft)
C6WL5 43N 146E
43N 147E
43N 148E
20/2100
21/0100
21/0300
W 50
W 65
NW 70
A8OO9 43N 146E
44N 148E
21/0000
21/0600
NW 55
NW 60
8.0/26
10.5/35
UDKC 49N 154E
48N 154E
21/0000
21/1200
E 50
N 55
A8OK6 49N 156E
47N 153E
21/1200
22/0000
NE 50
NW 50
4.5/15
8.5/28
A8OZ3 53N 164E 22/0600 W 45 10.5/35
OXBA2 50N 157E 22/1200 W 50
APL Thailand 50N 162E 22/1800 W 60

OPC North Pacific Surface Analysis charts OPC North Pacific Surface Analysis charts

Figure 4. OPC North Pacific Surface Analysis charts valid 0600 UTC January 30 (Part 2 - west) and 1800 UTC January 31, 2009 (Part 1 – east). (Click to enlarge)

North Pacific Storm, February 12-15: Figure 10 also shows a 988 hPa storm near 36N 162E moving northeast and following the Bering Sea system. It originated as the 1004 hPa low near Japan in the first part of Figure 10. The cyclone intensified into a hurricane force low near 41N 170E with a 972 hPa central pressure by 0000 UTC on the 14th. High resolution QuikSCAT winds revealed winds to 70 kts in the southwest semicircle of the low and similar to those of the preceding system. The World Spirit (ELWG7) reported northwest winds of 50 kts and seas 13.0 m (43 ft) near 41N 166E at 0000 UTC on the 14th. Six hours later the same ship reported west winds of 50 kts and seas 17.5 m (57 ft), although the author cannot confirm the accuracy of either report, especially the higher value. The vessel C6OT4 (47N 173E) reported north of the low with a northeast wind of 40 kts and seas 8.5 m (28 ft). The cyclone subsequently moved into the southeast Bering Sea where it weakened to a gale early on the 15th before moving into southwest Alaska.

North Pacific/ Bering Sea Storm, February 16-18: A secondary low on the front associated with low pressure near the Kurile Islands formed near 38N 159E early on February 16 and moved rapidly northeast to the western Bering Sea on the 17th, where it developed hurricane force winds ahead of the associated front. The central pressure fell 30 hPa in the twenty-four hour period ending at 0000 UTC on the 18th, when the center developed a central pressure of 962 hPa near 57N 174E. At 0900 UTC on the 17th the ship DPAK (55N 178W) reported southeast winds of 50 kts, while the nearby buoy 46035 (57.1N 177.9W) reported southeast winds of 40 kts and seas 4.5 m (15 ft) at 1200 UTC on the 17th. Six hours later 46035 reported east winds of 50 kts and seas 7.0 m (23 ft) and highest seas 11.0 m (36 ft) at 2300 UTC on the 17th. The 50 kts sustained wind at the buoy is remarkable since the buoy tends to under-report the wind compared to ships. A ship to the southeast near 55N 172W reporting with the SHIP callsign encountered southeast winds of 60 kts at 2100 UTC on the 17th, and nearby buoy 46073 (54.9N 172.0W) reported southeast winds of 40 kts three hours prior. Another vessel, DPBJ, reported southwest winds of 45 kts and seas 9.5 m (31 ft) at 1200 UTC February 18. The cyclone slowed down in the Bering Sea with its winds weakening to gale force on the morning of the 18th, before moving inland over Russia by the 19th.

Table 5. Ship observations taken during the passage of the storm of February 20-22, 2009 in the western North Pacific.
Observation Position Date/Time (UTC) Wind Seas (m/ft)
WDB9986 40N 158E 22/0600 NW 55 10.0/32
A8AW2 49N 159W 25/1200 SW 50
SeaLand Tacoma (KGTY) 55N 157W
55N 158W
26/1800
26/2300
W 55
W 55
13.0/42
6.5/21
WDD6039 57N 146W 26/1800 SW 35 11.5/37
Buoy 46075 54N 160.6W 26/0000
26/0200
NW 35 5.0/16
Maximum 6.5/22
Buoy 46062 59.7N 143.4W 26/0600 E 45 7.5/24
Buoy 46001 56.3N 148.0W 26/1500 SW 35 10.5/34
AMAA2 58.9N 152.0 26/0200 NE 55
Augustine Island (AUGA2) 59.4N 153.3W 26/0400 NE 50
High resolution QuikSCAT scatterometer image of satellite-sensed winds

Figure 5. High resolution QuikSCAT scatterometer image of satellite sensed winds around the storm shown in the second part of Figure 4. The valid time of the pass is 1705 UTC January 31, 2009, or about one hour prior to the valid time of the second part of Figure 4. The cyclone appears as a well-defined circulation with a center at 49N 163W near the upper left corner of the image, with the strongest winds on the south and west sides. Image is courtesy of NOAA/NESDIS/ Office of Research and Applications. (Click to enlarge)

Western North Pacific/ Bering Sea Storm, February 19-21: Two hurricane force cyclones formed in the western North Pacific almost simultaneously in late February (Figure 12). The first of these is shown fully developed and at maximum intensity well south of the western Aleutians in the first part of Figure 12. It originated as a frontal wave of low pressure near 30N 163E twenty-four hours prior with its central pressure dropping 40 hPa during this period, quite impressive at that lower latitude. High resolution QuikSCAT imagery near the valid time of the first part of Figure 12 showed winds to 65 kts in the south semicircle of the cyclone but a much larger area of storm force winds extending south and southwest of the center. The Star Gran (LADR4) reported west winds of 40 kts and seas 13.0 m (43 ft) near 31N 169E at 1800 UTC on the 19th. The Dresden Express (DHDE) reported southwest winds of 55 kts near 34N 173E one hour later, followed eleven hours later by a report of west winds of 50 kts near 33N 169E. The buoy 46071 (51.2N 179.1E) reported east winds of 45 kts and seas 8.0 m (26 ft) at 1600 UTC on the 20th, and maximum seas 10.0 m (32 ft) five hours later. The cyclone subsequently formed a new center to the north which took over as the main storm center in the Bering Sea as depicted in the second part of Figure 12. Top winds weakened to gale force as the system passed inland over Russia late on the 21st.

OPC North Pacific Surface Analysis charts OPC North Pacific Surface Analysis charts

Figure 6. OPC North Pacific Surface Analysis charts (Part 2) valid 1200 UTC January 31 and 1200 UTC February 2, 2009.

North Pacific/ Bering Sea Storm, February 24-25: This cyclone intensified while tracking northeast from Japan on February 22, to the western Aleutian Islands on the 24th and through the Bering Sea on the 25th. The low developed hurricane force winds and a lowest central pressure of 980 hPa, near 58N 172W at 1200 UTC on the 25th. High resolution QuikSCAT imagery revealed 65 kts west to northwest winds on the south side near 0600 UTC on the 25th. The ship 3FMQ6 (53N 178E) reported northwest winds of 50 kts and seas 7.0 m (23 ft) at 0400 UTC on the 25th. A vessel with the SHIP callsign (58N 174W) encountered northwest winds of 60 kts and 6.0 m seas (20 ft) at 1500 UTC on the 25th. Buoy 46073 (54.9N 172W) at 1100 UTC on the 25th reported southwest winds of 55 kts and seas 7.0 m (23 ft) followed by maximum seas of 10.0 m at 1600 UTC on the 25th . The cyclone moved inland over mainland Alaska late on the 25th and then redeveloped as a gale in the Gulf of Alaska the next day, with the new center dropping southeast and finally dissipating off Vancouver Island on the 28th.

High resolution QuikSCAT scatterometer image of satellite-sensed winds

Figure 7. High resolution QuikSCAT scatterometer image of satellite sensed winds around the storm depicted in the first part of Figure 6. The valid time of the pass is 0906 UTC January 31, 2009, or about three hours prior to the valid time of the first part of Figure 6. The storm center appears near 37N 143E off the central coast of Japan’s main island. Image is courtesy of NOAA/NESDIS/ Office of Research and Applications. (Click to enlarge)


OPC North Pacific Surface Analysis charts OPC North Pacific Surface Analysis charts

Figure 8. OPC North Pacific Surface Analysis charts (Part 2) valid 0600 UTC February 6 and 7, 2009. (Click to enlarge)

Eastern North Pacific Storm, February 28-March 2: This cyclone developed west of southern California near 135W early on February 27 and moved north, developing into a storm force low by 0000 UTC March 1 near 42N 135W with a 979 hPa central pressure. Strong high pressure which developed to the northwest helped produce northwest winds to 60 kts on the west side as revealed in the morning QuikSCAT pass on March 1. The ship DDYZ2 (39N 130W) reported southeast winds of 55 kts at 0600 UTC February 28. The buoy 46006 (40.1N 137.5W) reported maximum seas 10 m (33 ft) at 1100 UTC March 1. The cyclone developed a lowest central pressure of 971 hPa near 48N 134W early on the 2nd before weakening to a gale that day and turning southeast while continuing to weaken.

High resolution QuikSCAT scatterometer image of satellite-sensed winds

Figure 9. High resolution QuikSCAT scatterometer image of satellite sensed winds around the storm shown in Figure 8. The valid time of the pass is 1928 UTC February 6, 2009, or about ten and one half hours prior to the valid time of the second part of Figure 8. The center of the cyclone appears near 38N 158E in the upper-middle part of the image. Image is courtesy of NOAA/NESDIS/ Office of Research and Applications. (Click to enlarge)

North Pacific Storms, March 2-5: The main development in the western North Pacific was preceded by the formation of a 1014 hPa low to the northwest of the main low, near 39N 145E at 0000 UTC March 2. This low quickly intensified to a compact 992 hPa hurricane force low eighteen hours later as it dropped southeastward in the rear of the larger 986 hPa developing hurricane force low to the east. A ship reported west winds of 65 kts near this small cyclone. The center became absorbed into the larger system by 0600 UTC March 3. The combined system deepened to 972 hPa near 42N 170E at 1200 UTC on the 3rd, when it briefly developed hurricane force winds on the morning of the 3rd. The cyclone then followed a track similar to that of the February 10-14 event, with the cyclone weakening rapidly north of the Bering Strait by the 6th.

OPC North Pacific Surface Analysis charts OPC North Pacific Surface Analysis charts

Figure 10. OPC North Pacific Surface Analysis charts (Part 2) valid 1200 UTC February 11 and 0000 UTC February 13, 2009. (Click to enlarge)

High resolution QuikSCAT scatterometer image of satellite-sensed winds

Figure 11. High resolution QuikSCAT scatterometer image of satellite sensed winds around the south and west sides of the large Bering Sea storm shown in the second part of Figure 10. The valid time of the pass is approximately 0635 UTC February 13, 2009, or about six and one half hours later than the valid time of the second part of Figure 10. The center of the storm was near 58N 174W at this time. Wind barbs are absent in the ice covered northern Bering Sea. The numbered diagonal lines are cross-track time lines of the satellite (UTC), and a color scale for wind barbs (kts) is on the upper right edge of the image. The stronger winds in the upper part of the image may be unreliable due to ice edge contamination. Image is courtesy of NOAA/NESDIS/ Office of Research and Applications, adapted for OPC operational use. (Click to enlarge)

North Pacific Storm, March 4-7: The next storm system organized after moving east off Japan on March 4, just southeast of Japan. The cyclone intensified to storm force on the 4th and to hurricane force by the 5th. The system developed a central pressure of 985 hPa by that time but the circulation was relatively compact with some hurricane force winds even on the north side as well as up to 70 kts on the southwest side, as revealed in QuikSCAT data on the night of the 4th. The ship 3FCA9 (33N 157E) reported south winds of 45 kts and seas 3.5 m (11 ft) at 0000 UTC on the 5th. A vessel with the SHIP identifier (43N 180W) encountered southeast winds of 45 kts and seas 8.0 m (27 ft) at 1200 UTC on the 6th. The cyclone developed a lowest central pressure of 978 hPa near 44N 174E at 1200 UTC on the 6th and then maintained similar central pressures while passing north through the Bering Sea on the 7th and 8th but its winds lowered to gale force in the Bering Sea on the 7th.

OPC North Pacific Surface Analysis charts OPC North Pacific Surface Analysis charts

Figure 12. OPC North Pacific Surface Analysis charts (Part 2) valid 0600 UTC February 20 and 21, 2009. (Click to enlarge)

High resolution QuikSCAT scatterometer image of satellite-sensed winds

Figure 13. High resolution QuikSCAT scatterometer image of satellite sensed winds around the hurricane force low near the central Kurile Islands shown in the second part of Figure 12. The valid time of the pass is 0818 UTC February 21, 2009, or about two hours later than the valid time of the second part of Figure 12. The center of the storm is near 47N 155E with the Kurile Islands appearing to the northwest. Image is courtesy of NOAA/NESDIS/ Office of Research and Applications. (Click to enlarge)

Western North Pacific Storm, March 6-8: As the preceding event was reaching its maximum, new development was occurring near the coast of Japan. After moving off the coast it turned north along 150W and became a hurricane force low with an intensity similar to that of the preceding event. The cyclone developed a lowest central pressure of 977 hPa near 51N 149E at 1800 UTC on the 7th. A ship ahead of the storm’s front, UGPK near 53N 153E, reported a southeast wind of 70 kts and seas 10.0 m (32 ft) six hours later. The cyclone then redeveloped eastward to a new center near the central Aleutians late on the 8th which then stalled and weakened in the northern Bering Sea on the 10th.

OPC North Pacific Surface Analysis charts OPC North Pacific Surface Analysis charts

Figure 14. OPC North Pacific Surface Analysis charts (Part 2) valid 0000 UTC March 10 and 11, 2009. (Click to enlarge)

Western North Pacific and Bering Sea Storm, March 9-12: The development of this stronger event is depicted in Figure 14. The central pressure dropped 37 hPa in the twenty-four hour period ending at 0000 UTC on the 11th, with the second part of Figure 14 showing the cyclone at maximum intensity. The wind circulation around the cyclone is impressive with storm force or higher winds almost surrounding the center as seen in QuikSCAT (Figure 15). Hurricane force winds lasted until the morning of the 11th. The APL Philippines (WCX8884) near 38N 144E reported west winds of 55 kts and seas 10.5 m (35 ft) at 1800 UTC on the 10th. Another vessel, LAXP4 (47N 154E) encountered northeast winds of 50 kts and seas 12.5 m (41 ft) at 0000 UTC March 11. The cyclone subsequently weakened while drifting northeast, with dissipation occurring near the western Aleutians late on the 12th.

High resolution QuikSCAT scatterometer image of satellite-sensed winds

Figure 15. High resolution QuikSCAT scatterometer image of satellite sensed winds around another hurricane force low tracking north near the central Kurile Islands shown in the second part of Figure 14. The valid time of the pass is 1901 UTC March 10, 2009, or about five hours prior to the valid time of the second part of Figure 14. The well defined center of the storm appears near 44N 153E with the Kurile Islands appearing to the northwest. Image is courtesy of NOAA/NESDIS/ Office of Research and Applications. (Click to enlarge)

North Pacific Storm, March 21-26: The initial development of this cyclone is depicted in Figure 16 with the rapid intensification of a low pressure wave on a front over a twenty-four hour period. High resolution scatterometer data (Figure 17) reveals a swath of 50 to 75 kts winds south and west of the center. The strongest winds in this event were at this time. The cyclone weakened to a gale near 34N 164E late on March 22 as redevelopment on the front to the north occurred. The new low accelerated northeast and intensified to a hurricane force low near 40N 178W at 0600 UTC on the 24th. The central pressure lowered to 969 hPa as the center passed near 50N 164W at 1200 UTC on the 25th. The winds weakened to storm force as the system passed east of 160W, with the winds weakening further to gale force in the northern Gulf of Alaska late on the 26th. Dissipation followed on March 28. Table 5 is a list of selected ship, buoy and coastal automated C/MAN station observations taken during this event.

OPC North Pacific Surface Analysis charts OPC North Pacific Surface Analysis charts

Figure 16. OPC North Pacific Surface Analysis charts (Part 2) valid 0600 UTC March 21 and 22, 2009. (Click to enlarge)

High resolution QuikSCAT scatterometer image of satellite-sensed winds

Figure 17. High resolution QuikSCAT scatterometer image of satellite sensed winds around the relatively compact cyclone south of the Kamchatka Peninsula shown in the second part of Figure 16. The valid time of the pass is 1916 UTC March 21, 2009, or about ten and three quarters hours prior to the valid time of the second part of Figure 16. The center of the storm appears near 42N 160E in the lower right side of the image. Image is courtesy of NOAA/ NESDIS/ Office of Research and Applications. (Click to enlarge)

Western North Pacific Storm, April 1-4: The development of this cyclone is depicted in Figure 18. It originated as a frontal wave of low pressure just south of Japan late on March 31 and underwent the most rapid intensification in the twenty-four hour period ending at 1800 UTC April 2, when the central pressure dropped 27 hPa. Figure 19 is a QuikSCAT image of the storm near the time when it developed hurricane force winds. The stronger winds appear ahead of the occluded front where there are wind barbs as high as 70 kts. The lowest central pressure reached was 968 hPa when the center passed near44N 160E at 1200 UTC on the 3rd. A weakening trend began thereafter as the cyclone moved northeast, with the highest winds diminishing to gale force as the center approached the western Aleutians on the 4th. The weakening system then passed north through the Bering Sea on the 5th and 6th. The APL Thailand (WCX8882) near 54N 170W reported east winds of 40 kts and seas 9.5 m seas (31 ft) at 0600 UTC April 4. These were the highest conditions reported by ships.

OPC North Pacific Surface Analysis charts OPC North Pacific Surface Analysis charts

Figure 18. OPC North Pacific Surface Analysis charts (Part 2) valid 1800 UTC April 1 and 2, 2009. (Click to enlarge)

High resolution QuikSCAT scatterometer image of satellite-sensed winds

Figure 19. High resolution QuikSCAT scatterometer image of satellite sensed winds around the hurricane force storm shown in the second part of Figure 18. The valid time of the pass is 1904 UTC April 2, 2009, or about one hour later than the valid time of the second part of Figure 18. The center of the storm appears near 43N 155E in the lower left side of the image. The Kurile Islands appear to the northwest. Image is courtesy of NOAA/NESDIS/ Office of Research and Applications. (Click to enlarge)

North Pacific Storm, April 7-9: This cyclone, similar in intensity to the preceding event, originated as a frontal wave of low pressure near 36N 157E with a 1009 hPa central pressure at 0000 UTC April 7. It headed northeast and deepened by 12 hPa in the next twenty-four hours and then dropped another 24 hPa in the following twenty-four hour period ending at 0000 UTC on the 9th, when OPC analyzed the cyclone as a hurricane force low with a 973 hPa pressure. High resolution scatterometer data showed an area of west winds 50 to as high as 65 kts south of the center as it passed just south of the western Aleutian Islands. The lowest central pressure was 969 hPa when the center passed near 52N 180W six hours later. The ship A8AW2 (45N 173E) reported west winds of 45 kts and seas 6.5 m seas (21 ft) at 1800 UTC on the 8th. Another vessel, OUJI2 (54N 179E), encountered north winds of 45 kts at 1200 UTC April 9. Buoy 46072 (51.6N 172.1W) reported maximum seas of 10.0 m (33 ft) at 1800 UTC on the 9th. Slow weakening began as the storm passed south of the eastern Aleutians on the 9th and the winds lowered to gale force as the center passed near the Alaska Peninsula. The system then stalled in the northern Gulf of Alaska on the 11th and dissipated by the 13th.

References

Von Ahn, Joan. and Sienkiewicz, Joe, Hurricane Force Extratropical Cyclones Observed Using QuikSCAT Near Real Time Winds, Mariners Weather Log, Vol. 49, No. 1, April 2005.

http://en.wikipedia.org/wiki/2009_ Pacific_typhoon_season.html

Bancroft, George, Marine Weather Review – North Atlantic Area September to December 2008, Mariners Weather Log, Vol. 52, No. 4, April 2009.

QuikSCAT in the Ocean Prediction Center, http://www.opc.ncep.noaa. gov/quikscat/index.shtml

Sienkiewicz, Joe and Chesneau, Lee, Mariner’s Guide to the 500 Millibar Chart, Mariners Weather Log, Vol. 52, Number 3, December 2008

Saffir-Simpson Scale of Hurricane Intensity, http://www.nhc.noaa.gov/ aboutsshs.shtml

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