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Category 6 has moved! See the latest from Dr. Jeff Masters and Bob Henson here.A Quiet Start to the Eastern Pacific Hurricane and Northwest Pacific Typhoon Seasons
The 2016 Eastern Pacific hurricane season officially begins on Sunday, May 15, and should be quieter than the crazy 2015 season. Last year set a record for the most major hurricanes (Category 3 or higher) ever recorded in the Eastern Pacific east of 140°W, with nine such storms (reliable records go back to 1971.) One of those 2015 hurricanes was Earth's strongest tropical cyclone ever measured, Hurricane Patricia of October 2015, which reached astonishing sustained wind speeds of 215 mph. The year 2016 should see fewer major hurricanes in the northeast Pacific, thanks to cooler sea surface temperatures (SSTs) and less favorable upper-level winds brought on by what appears to be an emerging La Niña event. In their May 12 update, NOAA predicted a 70% chance of La Niña conditions emerging by the August-September-October peak of the Northern Hemisphere hurricane season. SSTs off the Pacific coast of Mexico this week were about 1°C (1.8°F) cooler than what they were last year in mid-May (Figure 1), and will likely continue to cool (relative to average) during the next few months. The forecast for the 2016 Eastern Pacific hurricane season, issued on May 6 by Mexico's Servicio Meteorológico Nacional (SMN), predicted 17 named storms, 9 hurricanes, and 4 major hurricanes. This is close to the average numbers (east of 140°W) from 1981 - 2010, which were 15 named storms, 8 hurricanes, and 4 major hurricanes. The 2015 Northeast Pacific hurricane season (east of 140°W) featured 18 named storms, 13 hurricanes, and 9 major hurricanes.
Figure 1. Change in Sea Surface Temperature (SST) between May 11, 2015 and May 11, 2016. Ocean temperatures are much cooler this year along the equator in the Pacific, signifying the transition from El Niño to La Niña conditions. SSTs are also much cooler off the Pacific coast of Mexico. Image credit: NOAA/ESRL.
A quieter hurricane season likely for Hawaii
Hawaii, which has been under the gun during the past two hurricane seasons--with one direct hit by a tropical storm (Iselle in 2014) and a number of close calls--should get a bit of a break in 2016. About half as many named storms form in the Central Pacific between 120°W and 180°W in a La Niña year, compared to an El Niño year. Hawaii is about three times less likely to be impacted by a tropical cyclone in a La Niña vs. an El Niño year, according to Phil Klotzbach, a hurricane forecaster at Colorado State University.
We've already had one hurricane in the Central Pacific this year--Category 2 Hurricane Pali became the earliest hurricane on record in the Central Pacific on January 11, 2016, and later dissipated on January 14. This storm was more a carry-over from the record-breaking Central Pacific hurricane season of 2015, though, which had exceptionally low wind shear and record-warm ocean temperatures. In 2015, the Central Pacific (between 140°W and 180°W) had 14 named storms, 8 hurricanes, and 5 major hurricanes form in or track through the basin--all of which were new records. Between 1981 - 2010, the Central Pacific had an average of 3.4 named storms, 1.5 hurricanes, and 0.7 major hurricanes form or track through the basin per year.
Figure 2. MODIS visible satellite image of Hurricane Pali taken on the afternoon of January 12, 2016. At the time, Pali was at peak strength--a Category 2 storm with 100 mph winds. Hurricane Pali became the earliest hurricane on record in the Central Pacific Ocean on January 11, 2016, and dissipated on January 14. The previous record for the earliest hurricane in the Central Pacific was Hurricane Ekeka on January 30, 1992. El Niño played a role in the formation of Pali. According to the discussion issued January 7, 2016 by the Central Pacific Hurricane Center, "This low-latitude out-of-season system has tapped into significant directional shear of the low-level winds, with an El Niño related westerly wind burst south of the system, and prevailing easterly trade winds to the north providing the large scale conditions conducive for development." Image credit: NASA.
Look for the season's first storm in early June
Several recent runs of the 16-day GFS model forecast have shown a tropical depression or Tropical Storm Agatha forming in the Eastern Pacific between Mexico and Hawaii during the last week of May, though these forecasts are too far in the future to be reliable. According to the Weather Company's long-range forecasting expert Dr. Mike Ventrice, the Eastern Pacific has a good chance of seeing its first storm of the season during the period May 30 - June 5, though. A Madden-Julian Oscillation (MJO) event is currently gaining amplitude over the Indian Ocean, and the European weekly model projects this MJO will pass through the Eastern Pacific during May 30 - June 5. The MJO often provides the necessary kick to spin up a tropical storm, especially over the Eastern Pacific and Atlantic Basins.
Figure 3. Super Typhoon Maysak as seen from the International Space Station at approximately 6 pm EDT Tuesday March 31, 2015 (just after dawn local time.) At the time, Maysak was a Category 5 storm at peak intensity, with sustained winds of 160 mph (as estimated by the Joint Typhoon Warning Center) and a central pressure of 905 mb (as estimated by the Japan Meteorological Agency.) Maysak was the strongest typhoon ever observed in the Northwest Pacific prior to April, and one of only three Category 5 typhoons ever observed in the Northwest Pacific so early in the year. Maysak killed nine and did $8.5 million in damage to several small islands in the Federated States of Micronesia, making it Micronesia's second deadliest and second most expensive storm in recorded history.
TSR predicts a below-average Northwest Pacific typhoon season
Last year was one of the busiest typhoon seasons on record in the Northwest Pacific, with a record number of Category 3 and stronger storms--sixteen--and an ACE index that was the third highest on record (479, behind only 2004's ACE of 481 and 1997's ACE of 568). This year should be much quieter, though. The May 7 forecast for the 2016 Northwest Pacific typhoon season made by British private forecasting firm Tropical Storm Risk, Inc. (TSR) calls for a below-active season with 22 named storms, 13 Category 1 or stronger typhoons, 6 major Category 3 or stronger typhoons, and an Accumulated Cyclone Energy (ACE) of 217. The long-term averages for the past 51 years are 26 named storms, 16 typhoons, 9 major typhoons, and an ACE of 298. TSR rates their skill level as modest for these late May forecasts--13% to 30% higher than a "no-skill" forecast made using climatology. TSR’s main predictor for their typhoon season forecast is the forecast sea surface temperatures (SSTs) during August - September 2016 in the region 5 ̊S - 5 ̊N, 140 ̊W - 180 ̊W, which they expect to be moderately cooler than average (-0.8°C from average.) Cool waters in this region are typically associated with stronger trade winds over the region 2.5°N-12.5°N, 120°E-180°E, the Northwest Pacific region where most major typhoons form. Stronger trade winds in that region tend to interfere with the amount of spin developing typhoons can get, leading to quieter typhoon seasons.
Using Dr. Phil Klotzbach's handy new Tropical Cyclone Activity stats page, we can see that the Northwest Pacific is off to a slow start this year. There have not been any named storms yet, and typically, we should have seen two by now. Last year, there had already been seven named storms in the Northwest Pacific by this point in the year, including three storms that became Category 5 typhoons.
Northern Indian Ocean tropical cyclone season underway
An area of disturbed weather formed on Thursday evening in the North Indian Ocean about 400 miles east of Sri Lanka. According to the Tropical Weather Discussion from the Joint Typhoon Warning Center, the disturbance has favorable conditions for development--low wind shear and very warm ocean waters about 2°C above average. Recent runs of the GFS and European model show this storm moving over Sri Lanka and South India on Sunday and Monday. The disturbance may have enough time over water to become the first tropical depression of the season in the North Indian Ocean, before interaction with land halts development. The Northern Indian Ocean has two tropical cyclone seasons--one that peaks in late May, just before the arrival of the Southwest Monsoon, and one that peaks in November, after the monsoon has waned. During the June - October peak of the monsoon, tropical cyclone formation is suppressed by the atmospheric circulation associated with the monsoon. This year's May tropical cyclone season has the potential to produce some unusually intense tropical cyclones, since SSTs across the basin are at record to near-record warm levels, 1 - 2°C above average.
Jeff Masters
Figure 1. Change in Sea Surface Temperature (SST) between May 11, 2015 and May 11, 2016. Ocean temperatures are much cooler this year along the equator in the Pacific, signifying the transition from El Niño to La Niña conditions. SSTs are also much cooler off the Pacific coast of Mexico. Image credit: NOAA/ESRL.
A quieter hurricane season likely for Hawaii
Hawaii, which has been under the gun during the past two hurricane seasons--with one direct hit by a tropical storm (Iselle in 2014) and a number of close calls--should get a bit of a break in 2016. About half as many named storms form in the Central Pacific between 120°W and 180°W in a La Niña year, compared to an El Niño year. Hawaii is about three times less likely to be impacted by a tropical cyclone in a La Niña vs. an El Niño year, according to Phil Klotzbach, a hurricane forecaster at Colorado State University.
We've already had one hurricane in the Central Pacific this year--Category 2 Hurricane Pali became the earliest hurricane on record in the Central Pacific on January 11, 2016, and later dissipated on January 14. This storm was more a carry-over from the record-breaking Central Pacific hurricane season of 2015, though, which had exceptionally low wind shear and record-warm ocean temperatures. In 2015, the Central Pacific (between 140°W and 180°W) had 14 named storms, 8 hurricanes, and 5 major hurricanes form in or track through the basin--all of which were new records. Between 1981 - 2010, the Central Pacific had an average of 3.4 named storms, 1.5 hurricanes, and 0.7 major hurricanes form or track through the basin per year.
Figure 2. MODIS visible satellite image of Hurricane Pali taken on the afternoon of January 12, 2016. At the time, Pali was at peak strength--a Category 2 storm with 100 mph winds. Hurricane Pali became the earliest hurricane on record in the Central Pacific Ocean on January 11, 2016, and dissipated on January 14. The previous record for the earliest hurricane in the Central Pacific was Hurricane Ekeka on January 30, 1992. El Niño played a role in the formation of Pali. According to the discussion issued January 7, 2016 by the Central Pacific Hurricane Center, "This low-latitude out-of-season system has tapped into significant directional shear of the low-level winds, with an El Niño related westerly wind burst south of the system, and prevailing easterly trade winds to the north providing the large scale conditions conducive for development." Image credit: NASA.
Look for the season's first storm in early June
Several recent runs of the 16-day GFS model forecast have shown a tropical depression or Tropical Storm Agatha forming in the Eastern Pacific between Mexico and Hawaii during the last week of May, though these forecasts are too far in the future to be reliable. According to the Weather Company's long-range forecasting expert Dr. Mike Ventrice, the Eastern Pacific has a good chance of seeing its first storm of the season during the period May 30 - June 5, though. A Madden-Julian Oscillation (MJO) event is currently gaining amplitude over the Indian Ocean, and the European weekly model projects this MJO will pass through the Eastern Pacific during May 30 - June 5. The MJO often provides the necessary kick to spin up a tropical storm, especially over the Eastern Pacific and Atlantic Basins.
Figure 3. Super Typhoon Maysak as seen from the International Space Station at approximately 6 pm EDT Tuesday March 31, 2015 (just after dawn local time.) At the time, Maysak was a Category 5 storm at peak intensity, with sustained winds of 160 mph (as estimated by the Joint Typhoon Warning Center) and a central pressure of 905 mb (as estimated by the Japan Meteorological Agency.) Maysak was the strongest typhoon ever observed in the Northwest Pacific prior to April, and one of only three Category 5 typhoons ever observed in the Northwest Pacific so early in the year. Maysak killed nine and did $8.5 million in damage to several small islands in the Federated States of Micronesia, making it Micronesia's second deadliest and second most expensive storm in recorded history.
TSR predicts a below-average Northwest Pacific typhoon season
Last year was one of the busiest typhoon seasons on record in the Northwest Pacific, with a record number of Category 3 and stronger storms--sixteen--and an ACE index that was the third highest on record (479, behind only 2004's ACE of 481 and 1997's ACE of 568). This year should be much quieter, though. The May 7 forecast for the 2016 Northwest Pacific typhoon season made by British private forecasting firm Tropical Storm Risk, Inc. (TSR) calls for a below-active season with 22 named storms, 13 Category 1 or stronger typhoons, 6 major Category 3 or stronger typhoons, and an Accumulated Cyclone Energy (ACE) of 217. The long-term averages for the past 51 years are 26 named storms, 16 typhoons, 9 major typhoons, and an ACE of 298. TSR rates their skill level as modest for these late May forecasts--13% to 30% higher than a "no-skill" forecast made using climatology. TSR’s main predictor for their typhoon season forecast is the forecast sea surface temperatures (SSTs) during August - September 2016 in the region 5 ̊S - 5 ̊N, 140 ̊W - 180 ̊W, which they expect to be moderately cooler than average (-0.8°C from average.) Cool waters in this region are typically associated with stronger trade winds over the region 2.5°N-12.5°N, 120°E-180°E, the Northwest Pacific region where most major typhoons form. Stronger trade winds in that region tend to interfere with the amount of spin developing typhoons can get, leading to quieter typhoon seasons.
Using Dr. Phil Klotzbach's handy new Tropical Cyclone Activity stats page, we can see that the Northwest Pacific is off to a slow start this year. There have not been any named storms yet, and typically, we should have seen two by now. Last year, there had already been seven named storms in the Northwest Pacific by this point in the year, including three storms that became Category 5 typhoons.
Northern Indian Ocean tropical cyclone season underway
An area of disturbed weather formed on Thursday evening in the North Indian Ocean about 400 miles east of Sri Lanka. According to the Tropical Weather Discussion from the Joint Typhoon Warning Center, the disturbance has favorable conditions for development--low wind shear and very warm ocean waters about 2°C above average. Recent runs of the GFS and European model show this storm moving over Sri Lanka and South India on Sunday and Monday. The disturbance may have enough time over water to become the first tropical depression of the season in the North Indian Ocean, before interaction with land halts development. The Northern Indian Ocean has two tropical cyclone seasons--one that peaks in late May, just before the arrival of the Southwest Monsoon, and one that peaks in November, after the monsoon has waned. During the June - October peak of the monsoon, tropical cyclone formation is suppressed by the atmospheric circulation associated with the monsoon. This year's May tropical cyclone season has the potential to produce some unusually intense tropical cyclones, since SSTs across the basin are at record to near-record warm levels, 1 - 2°C above average.
Jeff Masters
The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.