Marine Weather Review – North Atlantic Area
May through August 2010

By George P. Bancroft Ocean Forecast Branch, Ocean Prediction Center, Camp Springs, MD NOAA National Center for Environmental Prediction

Introduction

The period of May to August 2009 includes the late spring and summer months. Although cyclonic activity normally decreases during the period through July, the North Atlantic continued to produce cyclones with storm force winds during this period with May being most active. Although there was some drop off in frequency of such cyclones during the summer months, the first half of July produced two intense cyclones in the northern waters with central pressures below 970 hPa, and a third almost as intense. Unlike the same period of 2009, there were no non tropical lows producing hurricane force winds. The last half of July and first half of August were relatively quiet, followed by increasing activity in late August as fall approached. Most of the lows originated near the Canadian or northeast U.S. coasts and intensified as they moved northeast or east out over the North Atlantic toward the Greenland or northwestern Europe, except in May when blocking high pressure caused then to stall or move erratically off eastern Canada.

Two tropical systems affected OPC’s marine area of responsibility north of 31N. In early August weakening Tropical Storm Colin affected waters southwest of Bermuda. A slowly weakening Hurricane Danielle passed well east of Bermuda and became extratropical at the end of August.

Tropical Activity

Tropical Storm Colin: Tropical Storm Colin passed near 31N 66W at 0900 UTC August 8 with maximum sustained winds of 35 kts with gusts to 45 kts but was downgraded to a depression the same morning, with dissipation following late on the 8th near 33N 66W.

Hurricane Danielle: Formerly a major hurricane south of OPC’s waters, Danielle moved north into OPC’s southwestern waters near 59W as a weakening hurricane on the evening of August 28 with maximum sustained winds of 90 kts with gusts to 110 kts, Category 2 on the Saffir-Simpson scale of intensity (Reference 1). The cyclone made a gradual turn toward the east around the subtropical ridge and weakened to a tropical storm near 41N 49W at 2100 UTC on the 30th with maximum sustained winds of 60 kts with gusts to 75 kts. The cyclone then merged with a nearby frontal zone three hours later and became post tropical (or extratropical) Danielle. Figure 1 depicts this transition of Danielle to an extratropical storm (second part of Figure 1). Figure 2 is a satellite image taken while Danielle was still classified as a hurricane but undergoing extratropical transition. It retains some circular cloud structure around the center (40N 52W) with possible convection to the northwest but is approaching nearby frontal cloud bands. Figure 3 shows winds around post tropical Danielle about thirteen hours after completion of extratropical transition. Given that ASCAT winds have low biases that increase at higher wind speeds, the appearance of southwest winds as high as 45 kts near the center supports classification of the cyclone as a storm force low. Danielle then turned more toward the northeast and weakened to a gale by the end of the month. High pressure over Europe and a larger cyclone to the north then turned Danielle to the north toward Greenland, where it dissipated late on September 3.

OPC North Atlantic Surface Analysis charts OPC North Atlantic Surface Analysis charts

Figure 1. OPC North Atlantic Surface Analysis charts valid 1200 UTC August 29 and 0000 UTC August 31, 2010. (Click to enlarge)

GOES13 infrared satellite image

Figure 2. GOES13 infrared satellite image valid 1045 UTC August 30, 2010. The valid time of the image is about 13 hours prior to the valid time of the second part of Figure 1. The satellite senses temperature on a scale from black (warm) to white (cold) in this type of imagery. (Click to enlarge)

ASCAT (Advanced Scatterometer) image of satellite sensed winds around post-tropical Danielle

Figure 3. ASCAT (Advanced Scatterometer) image of satellitesensed winds around post-tropical (or extratropical storm) Danielle shown in the second part of Figure 1. The resolution is 25 km versus 50 km in the coarser resolution version of the imagery. The western portion of the 1138 UTC pass and the eastern portion of the 1318 UTC pass, for August 31, 2010, are shown, with the passes overlapping north of 49N. These times are less than thirteen and one quarter hours later than the valid time of the second part of Figure 1. The center of the storm appears near 42N 41W in the lower left side of the image. Image is courtesy of NOAA/NESDIS Center for Satellite Application and Research. (Click to enlarge)

Other Significant Events of the Period

North Atlantic Storm, May 4-5: The month of May began with a developing low pressure system passing east across the Canadian Maritime Provinces and becoming a storm force low east of Newfoundland early on May 5 (Figure 4), when it developed its lowest central pressure of 974 hPa. Hibernia Platform (VEP717, 46.7N 48.7W) reported west winds of 55 kts at its 139 m anemometer height (Reference 2) at 0300 UTC May 6. The Terra Nova (VCXF, 46.4N 48.4W) with its lower anemometer height of 53 m reported west winds of 40 kts along with 4.5 m seas (14 ft) three hours prior. Among ships, BATEU07 (47N 59W) reported the highest winds, northwest 45 kts, at 1800 UTC May 4. The Barrington Island (C6QK) reported the highest seas of 8.0 m (26 ft) along with a west wind of 35 kts near 43N 41W at 1800 UTC on the 5th. Figure 5 is an ASCAT image showing wind retrievals of 40 kts on the morning of the 5th which may suggest the cyclone had minimal storm force winds. The cyclone turned toward the northwest on the 5th, blocked by high pressure to the east and northeast, and began to weaken, and became absorbed by another low approaching on a similar track on May 7.

OPC North Atlantic Surface Analysis charts OPC North Atlantic Surface Analysis charts

Figure 4. OPC North Atlantic Surface Analysis charts valid 1800 UTC May 3 and 0600 UTC May 5, 2010.

ASCAT (Advanced Scatterometer) image of satellite sensed winds around post-tropical Danielle



Figure 5. ASCAT 25 km scatterometer image of satellite-sensed winds around the southwest side of the storm east of Newfoundland shown in the second part of Figure 4. The valid time of the pass is 1401 UTC May 5, 2010, or about eight hours later than the valid time of the second part of Figure 4. The island of Newfoundland appears on the upper-left side of the image. Image is courtesy of NOAA/NESDIS/ Center for Satellite Application and Research. (Click to enlarge)


North Atlantic Storms, May 13-16: Figure 6 depicts the development of two storm force lows over the western waters. The first of these, in the first part of Figure 6, originated as a low pressure wave over the mid-Atlantic states early on May 12 and developed storm force winds when passing south of Newfoundland late on the 13th. The Training Ship Empire State VI (KKFW) near 38N 54W reported southwest winds of 45 kts and 7.5 m seas (25 ft) at 0700 UTC on the 14th. The CL New York (DPAK) encountered southwest winds of 50 kts and 9.0 m seas (30 ft) near 44N 45W at 0000 UTC on the 15th. A second system of similar intensity originated near the New England coast late on the 14th with the second part of Figure 6 showing this cyclone southeast of Newfoundland. This cyclone turned north and absorbed the other cyclone near Newfoundland while passing over the Grand Banks over the next twentyfour hours, becoming a large gale. The gale subsequently drifted northeast and weakened over the next few days, dissipating southeast of Greenland by the 21st.

OPC North Atlantic Surface Analysis charts OPC North Atlantic Surface Analysis charts

Figure 6. OPC North Atlantic Surface Analysis charts valid 0000 UTC May 15 and 1200 UTC May 16, 2010.(Click to enlarge)

Storm in Davis Strait, May 21-22: A frontal system approaching Greenland from the Labrador Sea on the 21st developed a secondary low on the front by 0600 UTC on the 22nd , with storm force winds near the southwest Greenland coast on the 21st. As the low moved northwest into the Davis Strait on the 22nd the front and associated winds weakened.

North Atlantic Storm, May 24- 26: A complex low pressure system moved from Atlantic Canada into the southern Labrador Sea by the 24th as two lows rotating around each other, with the northern low developing storm force winds that day. The system consolidated into a single 987 hPa storm near 51N 47W early on the 25th. Hibernia Platform (VEP717, 46.7N 48.7W) reported northwest winds of 50 kts at 0600 UTC on the 25th, just south of the area of strongest pressure gradient on the west side of the low. To the north the Mary Artica (BATEU00) near 59N 45W reported northeast winds of 43 kts seven hours later. At 2200 UTC May 26 the ship V7RI8 (43N 45W) encountered southwest winds of 45 kts and 4.0 m seas (13 ft). The cyclone lingered in that area for the next twenty-four hours before weakening and moving southwest and becoming absorbed by another low passing to the southeast late on the 28th, to be described next.

North Atlantic Storm, May 29-31: Figure 7 shows the final forty-eight hours of development of this third most intense low of the period. The storm originated from a frontal wave of low pressure near 41N 44W early on the 28th which absorbed several other lows to its northwest. The ASCAT imagery in Figure 8 displays winds to 45 kts north and southeast of the storm center at a time when the central pressure was 971 hPa. The Ludwigshafen Express (DILE) reported northwest winds of 40 kts near 52N 36W at 0600 UTC on the 30th. The cyclone then weakened to a gale on the 31st while drifting northeast, and passed north of the area June 2.

OPC North Atlantic Surface Analysis charts OPC North Atlantic Surface Analysis charts

Figure 7. OPC North Atlantic Surface Analysis charts valid 0600 UTC May 29 and 31, 2010. (Click to enlarge)

ASCAT (Advanced Scatterometer) image of satellite sensed winds around post-tropical Danielle




Figure 8. ASCAT 25 km image of satellite sensed winds around the storm shown in the second part of Figure 7. The image shows portions of two passes (1200 UTC and 1340 UTC), about 17-18 hours prior to the valid time of the second part of Figure 7. The southern tip of Greenland appears near the upper-left corner of the image. Image is courtesy of NOAA/NESDIS/Center for Satellite Application and Research. (Click to enlarge)


Western North Atlantic Storm, June 15-16: The next developing storm is depicted in Figure 9, as a frontal wave of low pressure south of Nova Scotia intensified rapidly while absorbing another low over southern Labrador. The central pressure dropped 25 hPa during the twenty-four hour period ending at 1800 UTC on the 15th. The cyclone subsequently drifted southeast and weakened to a gale force low on the 16th, before becoming absorbed by a new low forming in the Labrador Sea late on the 17th. Selected ship and platform reports taken in this event are listed in Table 1.

Table 1. Selected ship, oil platform and buoy observations taken during passage of the North Atlantic storm of January 9-12, 2010.
Observation Position Date/Time (UTC) Wind Seas (m/ft)
Courage (WDC6907) 40N 51W 15/1000 SW 45
Undine (SHJC) 47N 46W 15/1800 SE 50
BATFR43 46N 57W 16/0400 W 45
A8BZ6 17/0000 NW 40 6.7/22
Hibernia Platform (VEP717) 46.7N 48.7W 15/1500 SE 70 (height 139 m)
GSF Grand Banks (YJUF7) 46.7N 48W 15/1800 SE 50 (height 82 m)
Terra Nova (VCXF) 46.4N 48.4W 15/1800 SE 45 (height 53 m)


OPC North Atlantic Surface Analysis charts OPC North Atlantic Surface Analysis charts

Figure 9. OPC North Atlantic Surface Analysis charts valid 1800 UTC June 14 and 15, 2010.(Click to enlarge)

Northeastern Atlantic Storm, June 30-July 2: This cyclone originated as a frontal wave of low pressure near 46N 48W at 1200 UTC on June 29 which tracked northeast and rapidly deepened over the northeastern Atlantic after 0600 UTC on the 30th. The central pressure fell 26 hPa in the twenty-four hour period ending at 0600 UTC July 1, when OPC classified it as a storm force low. Six hours later the central pressure reached 968 hPa near 58N 19W, making this cyclone the most intense of the period, unusual for a July storm. This event was similar in location and intensity to another occurring less than a week later (Figure 10). At 0300 UTC July 1 the Arcadia (ZCDN2) near 62N 23W reported northeast winds of 55 kts and 7.5 m seas (24 ft). The Leverkusen Express (DEHY) near 50N 35W encountered 8.5 m seas (28 ft) along with 35 kts northwest winds at 1200 UTC June 30. Other ships in the area reported 40 kts or less. The cyclone subsequently weakened to a gale on July 2 while drifting northeast, before passing northeast of Iceland late on the 3rd.

OPC North Atlantic Surface Analysis charts OPC North Atlantic Surface Analysis charts

Figure 10. OPC North Atlantic Surface Analysis charts valid 1800 UTC July 5 and 6, 2010.(Click to enlarge)

Northeastern Atlantic Storm, July 6-7: This intense low developed from the merger of a southern frontal wave and a complex low pressure system passing to the north (Figure 10), reaching maximum intensity (central pressure 969 hPa) within twenty-four hours. The central pressure fell 31 hPa during this period using the northern low’s initial pressure. Such impressive deepening is reflected in a 500 hPa analysis (Figure 11) showing a short-wave trough and 70 to 85 kts wind maximum or jet stream. More information on use of the 500 hPa chart may be found in Reference 4 (Sienkiewicz and Chesneau, 2008). Figure 12 is a METEOSAT9 infrared satellite image of the storm near the time of maximum intensity, revealing well defined frontal features with cold tops and great vertical extent. Figure 13 provides limited coverage of this system but shows stronger winds on the southeast side of the cyclone, up to 45 kts, strongly suggestive of storm force winds. The Discovery (GLNE) near 57N 12W reported southwest winds of 45 kts and 6.7 m seas (22 ft). The buoy 64045 (59.2N 11.7W) reported southwest winds of 35 kts and 10.0 m seas (33 ft) at 0800 UTC on the 7th. Like its predecessor, this cyclone subsequently moved slowly northeast with a weakening trend and passed northeast of Iceland late on the 8th.

OPC North Atlantic Surface Analysis charts

Figure 11. OPC North Atlantic 500 hPa analysis valid 0000 UTC July 6, 2010, during the period of rapid intensification of the North Atlantic low pressure system shown in Figure 10. The chart is computer generated with short-wave troughs (dashed lines) manually added. (Click to enlarge)

OPC North Atlantic Surface Analysis charts

Figure 12. METEOSAT9 infrared satellite image over the northeastern Atlantic valid 2115 UTC July 6, 2010. The valid time of the image approximately three hours later than the valid time of the second part of Figure 10. Satellite senses temperature on a scale from black (warm) to white (cold) in this type of imagery. (Click to enlarge)

ASCAT (Advanced Scatterometer) image of satellite sensed winds around post-tropical Danielle




Figure 13: ASCAT 25 km scatterometer image of satellite-sensed winds around mainly the southeast side of the storm shown in the second part of Figure 10. The valid time of the pass is 2223 UTC July 6, 2010, or about four and one-half hours later than the valid time of the second part of Figure 10. The center of the storm appears near 59N 19W in the upperright side of the image. Image is courtesy of NOAA/NESDIS/Center for Satellite Application and Research. (Click to enlarge)


Northeastern Alantic Storm of July 11-13: The next developing cyclone took a more west to east track across the North Atlantic and was not as intense, moving off the southern Labrador coast early on July 11 and then becoming a storm with a 995 hPa central pressure near 54N 27W at 1800 UTC on the 12th. It turned toward the southeast and weakened to a gale southwest of Ireland the next day before turning northeast across Great Britain on the 14th and 15th. A new cyclone developed near the English Channel on the 15th and moved northeast, absorbing the other low on July 16. At 0500 UTC on the 12th the Berge Atlantic (LAIP5) near 52N 37W reported northwest winds of 45 kts. At 0000 UTC and 0200 UTC July 13 the ship BATFR04 (49.5N 26.5W) reported northwest winds of 48 kts. The Genco Acheron (VRCF7) near 50N 29W encountered 9.8 m seas (32 ft) along with 35 kts northwest winds at 0500 UTC on the 13th.

North Atlantic Storm, July 16-17: Figure 14 shows the rapid development of another intense July storm over the northern waters, from the merger of northern and southern lows over a twenty-four hour period. The central pressure fell 23 hPa during this period, and also in an earlier period ending at 0000 UTC on the 16th. The ship VRY03 (54N 49W) reported northeast winds of 55 kts and 6.5 m seas (21 ft) at 1700 UTC on the 16th. The cyclone developed a lowest central pressure of 973 hPa near 55N 44W at 1800 UTC on the 16th then drifted east toward Great Britain with a weakening trend through July 20th. Dissipation followed over northern France on the 23rd.

OPC North Atlantic Surface Analysis charts OPC North Atlantic Surface Analysis charts

Figure 14. OPC North Atlantic Surface Analysis charts valid 1200 UTC July 15 and 1200 UTC July 16, 2010.(Click to enlarge)

Northeastern Atlantic Storm, August 20: Low pressure formed on a front near 53N 12W, the northeastward redevelopment of a primary low pressure center 49N 29W at 0000 UTC August 19. This new low lifted north and briefly developed storm force winds southeast of the center by 1800 UTC on the 20th, near 58N 10W. An ASCAT 25 km pass from 1021 UTC that day revealed a small area of winds to 45 kts on the southeast side of a compact cyclone. A weakening trend followed as the cyclone moved into the Norwegian Sea on the 21st.

North Atlantic Storm, August 27- 28: The rapid development of this cyclone was farther south than most other events during this period, as high pressure to the north and east blocked its progression. Figure 15 shows the merging of two cyclones to form a storm force low in the second part of Figure 15. The ASCAT wind retrievals in Figure 16 reveal a swath of winds to 45 kts on the southwest and west sides of the cyclone displaced some distance from the center due to presence of an occluded front. These winds support the use of a “storm” label on OPC’s surface charts near this time. OPC downgraded the cyclone to a gale force low early on the 28th as it drifted north and weakened. The weakening system turned more northeast on the 29th as the blocking high retreated northeast and dissipated by the end of the month.

OPC North Atlantic Surface Analysis charts OPC North Atlantic Surface Analysis charts

Figure 14. OPC North Atlantic Surface Analysis charts valid 1200 UTC July 15 and 1200 UTC July 16, 2010.(Click to enlarge)

ASCAT (Advanced Scatterometer) image of satellite sensed winds around post-tropical Danielle




Figure 16.ASCAT 25 km scatterometer image of satellite sensed winds around the west side of the storm shown in the second part of Figure 15. The valid time of the pass is 2245 UTC August 27, 2010, or ten and three-quarters hours later than the valid time of the second part of Figure 15. The center of the storm is near the lower-right edge of the image. Image is courtesy of NOAA/NESDIS/Center for Satellite Application and Research. (Click to enlarge)


References
  1. Saffir-Simpson Scale of Hurricane Intensity: http://www.nhc.noaa.gov/ aboutsshs.shtml
  2. E-mail communication, Thomas, Bridget, Climate Data and Analysis Section (Environment Canada), October 28, 2008.
  3. Sienkiewicz, Joe and Chesneau, Lee, Mariner’s Guide to the 500 Millibar Chart, Mariner’s Weather Log, Vol. 52, Number 3, December 2008.

Back to top