Category Archives: Eastern and Central Pacific

TCs between Mexico and Hawaii

Odile Becomes a Hurricane

Tropical Storm Odile has intensified into a hurricane as it moves slowly toward the northwest off the west coast of Mexico.  At 11:00 a.m. EDT on Saturday the center of Hurricane Odile was located at latitude 16.6°N and longitude 106.0°W which put it about 200 miles south-southwest of Manzanillo, Mexico and about 505 miles south of the southern tip of Baja California.  Odile was moving toward the northwest at 6 m.p.h.  The maximum sustained wind speed was 80 m.p.h. and the minimum surface pressure was 980 mb.

The upper level high over northern Mexico that was generating northeasterly winds over Odile has shifted eastward.  As a result, the upper level wind shear has decreased and Odile is intensifying.  Odile will be over warm Sea Surface Temperatures (SSTs) during the next several days and it should continue to intensify.  A period of more rapid intensification is possible.

The winds in the middle level steering Odile should keep pushing it in a northwesterly direction.  Much of the computer guidance suggests that Odile will pass south of the tip of Baja California and then move west of Baja.  It could take a path similar to the track taken by Hurricane Norbert.

The government of Mexico issued a new Tropical Storm Watch for a portion of the coast of Baja California that extends from La Paz to Santa Fe.  A Tropical Storm Watch remains in effect for the portion of the coast from Manzanillo to Cabo Corrientes.

If Odile moves west of Baja California, southerly winds in the eastern half of the circulation could transport significant water vapor over the southwestern U.S.  In addition, a strong flow of moist air is occurring over northeastern Mexico associated with the northern portion of a tropical wave moving inland in that area.  The combination of these two flows of moist air could create a potential for locally heavy rains over parts of the southwestern U.S. next week.

 

Tropical Storm Odile Forms West of Mexico

Tropical Storm Odile formed west of Mexico on Wednesday.  At 11:00 p.m. EDT on Wednesday the center of Odile was located at latitude 15.5°N and longitude 103.5°W which put it about 195 miles south-southwest of Lazaro Cardenas and about 245 miles south-southeast of Manzanillo, Mexico.  Odile was moving toward the northwest at 3 m.p.h.  The maximum sustained wind speed was 45 m.p.h. and the minimum surface pressure was 1001 mb.

An upper level high pressure system over northern Mexico is generating northeasterly winds over Odile, which is creating moderate wind shear over the storm.  The shear is likely to continue in the short-term and then it will lessen.  Shear will likely limit the rate at which Odile intensifies during the next 12-24 hours.  However, if the shear lessens in a day or so, then Odile will be in an environment favorable for intensification with warm Sea Surface Temperatures and a period or more rapid intensification is possible.  Odile has a good chance of becoming a hurricane and there is a possibility that it could reach Major Hurricane intensity.

The mid level winds that would steer Odile are relatively light and so it is likely to move slowly in a general northwest or west-northwest direction.  With weak steering flow erratic motion may occur and the center could even be quasi-stationary at times.  An east-west mid-level ridge of high pressure over the Florida and the northeastern Gulf of Mexico will shift westward and eventually provide a stronger west-northwest or northwest steering flow for Odile.  As a result Odile will likely move roughly parallel to the coast of Mexico toward the southern tip of Baja California.  Recent indications suggest that the center will move west of Baja California like Hurricane Norbert did.

Although it looks less likely that the center of Odile will make landfall on the west coast of Mexico, uncertainty exists about the ultimate size of the wind field when Odile intensifies.  The Mexican government has issued a Tropical Storm Watch for the portion of the coast from Lazaro Cardenas northward to Manzanillo as a precaution in case the wind field expands to the point where tropical storm force winds reach the coast.

 

Norbert Reaches Major Hurricane Status

Despite being close to land and near much cooler Sea Surface Temperatures (SSTs) Hurricane Norbert intensified rapidly during the overnight hours and it has maximum sustained winds of 120 m.p.h.  This makes Norbert a Category 3 hurricane on the Saffir-Simpson Scale and it is considered to be a Major Hurricane.  At 8:00 a.m. EDT on Saturday the center of Norbert was located at latitude 24.8°N and longitude 113.8°W which put it about 95 miles west of Cabo San Lazaro and about 220 miles south-southeast of Punta Eugenia, Mexico.  Norbert was moving toward the northwest at 8 m.p.h.  The minimum surface pressure was estimated to be 957 mb.

The government of Mexico has adjusted the warnings issued for Norbert.  The Hurricane Warning has been discontinued.  Tropical Storm Warnings are now in effect for the portion of the coast from Santa Fe to Punta Eugenia and from San Evaristo to Loreto.

Norbert is expected to continue to move toward the northwest this weekend.  It will soon move over much cooler SSTs.  Once Norbert moves into that environment it will encounter much cooler, more stable air which will begin to lessen the convection.  As Norbert extracts less energy from the ocean and convection transports less energy upward, the circulation will begin to spin down.

The remnants of Norbert’s circulation could turn northeast and cross northern Baja California into the southwestern U.S. next week.  It is also possible that as the circulation around Norbert weakens, the upper and lower portions could decouple.  The upper and middle portion of the circulation could move over the southwestern U.S. and enhance the probability for rainfall there, while the lower level circulation remains nearly stationary and dissipates west of Baja California.

 

Norbert intensifies into Category 2 Hurricane

Hurricane Norbert has intensified in recent hours and the maximum sustained wind speed is now 110 m.p.h. which puts the hurricane at the high end of Category 2 on the Saffir-Simpson Scale.  The slow movement of Norbert has allowed the core of the hurricane to remain over Sea Surface Temperatures (SSTs) near 29°C.  The input of energy from the ocean has fueled convection around the eye.  The slow motion west of Baja California may have also allowed the inner core to tighten up and the mountains of Baja may have also reduced the vertical shear.  All of these factors have produced a more intense hurricane.

The center of Norbert is about 50 miles southwest of Cabo San Lazaro.  The hurricane force winds are still offshore, but some portions of the coast may be experiencing tropical storm force winds.  It is also possible that heavy rain may be falling in areas where the wind direction is enhancing the upslope motion.

Norbert should move over cooler SSTs during the weekend.  Less energy and more stable atmospheric conditions will result in decreased convection and the circulation around Norbert should start to spin down.

 

Hurricane Norbert a little stronger

An Air Force Reserve Hurricane Hunter aircraft found that Hurricane Norbert was little stronger than was estimated based on satellite imagery.  At 2:00 p.m. EDT on Thursday the center of Hurricane Norbert was located at latitude 20.8°N and longitude 110.6°W which put it about 150 miles south-southwest of the southern tip of Baja California.  Norbert has been moving somewhat erratically, but the estimated motion was toward the northwest at 7 m.p.h.  The aircraft found that the maximum sustained wind speed was 90 m.p.h. and the minimum surface pressure was 970 mb.

Norbert is expected to move generally toward the northwest during the next several days and to move roughly parallel to the west coast of Baja California.  Although the center is expected to remain offshore, winds to tropical storm force may reach parts of Baja California.  For that reason a Tropical Storm Warning has been issued for the portion of the coast that extends from La Paz southward to the southern tip of Baja California and then northward to Cabo San Lazaro, Mexico.  Tropical Storm Watches have been issued for the portions of the coast from La Paz northward to San Evaristo and from Cabo San Lazaro northward to Puerto San Andresito.

The eye appears to be becoming more evident on visible satellite images.  There is some upper level shear from the northeast, but some additional intensification is possible during the next 24 hours.  When Norbert begins to move west of Baja California it will move over a very strong gradient of Sea Surface Temperatures (SSTs) toward colder water.  It will move from SSTs near 30°C to SSTs near 23°C.  The colder SSTs will greatly reduce the energy available to drive the circulation.  In addition, the atmosphere tends to be quite stable over the cooler SSTs, which will further inhibit convection and help to spin down the circulation.

Where the wind direction creates a flow up the slopes of mountains, locally heavy rainfall could occur and the potential for flooding exists in some locations.  Southerly flow around the eastern side of Norbert’s weakening circulation could transport moisture into portions of the southwestern U.S.

 

Tropical Storm Norbert Intensifying

Tropical Storm Norbert is becoming more organized as it moves in the general direction of Baja California.  At 8:00 a.m. EDT the center of Norbert was located at latitude 19.7°N and longitude 108.3°W which put it about 245 miles south-southeast of the southern tip of Baja California.  Norbert was moving toward the west-northwest at 8 m.p.h.  The maximum sustained wind speed was 60 m.p.h. and the minimum surface pressure was 999 mb.  The Tropical Storm Watch for the portion of the coast from La Paz to Sante Fe, Mexico has been upgraded to a Tropical Storm Warning.  A Tropical Storm Watch has been issued for the portion of the coast from Sante Fe northward to Cabo San Lazaro.

Norbert is over warm Sea Surface Temperatures (SSTs) and the upper level wind shear appears to be decreasing.  Some satellite imagery is indicating that an eye could be forming in the mid-levels of the circulation.  Further intensification is likely and a period of more rapid intensification is possible.  Norbert could become a hurricane before it reaches cooler SSTs west of Baja California.

 

Tropical Storm Norbert Forms

A center of circulation developed within a trough of low pressure southwest of Manzanillo, Mexico and the National Hurricane Center classified it as Tropical Storm Norbert.  At 5:00 p.m. EDT the center of Tropical Storm Norbert was located at latitude 18.5°N and longitude 106.5°W which put it about 150 miles west-southwest of Manzanillo and about 375 miles south of the southern tip of Baja California.  Norbert was moving toward the north at 9 m.p.h.  The maximum sustained wind speed was 40 m.p.h. and the minimum surface pressure was 1004 mb.  The government of Mexico has issued a Tropical Storm Watch for Baja California Sur from La Paz, around the southern tip of Baja California to Santa Fe.

Although there is some northeasterly shear over Norbert, the tropical storm is expected to intensify and at least one numerical model is predicting that it will become a hurricane.  Since Norbert is still in the organization stage, the track forecast has a higher than normal degree of uncertainty.  Many models are predicting that Norbert will move toward Baja California, but turn west-northwest before the storm reaches the coast.  The government of Mexico issued a Tropical Storm Watch for a portion in the coast in case Norbert moves closer to the coast than is currently expected.

 

Category 5 Hurricane Marie

Hurricane Marie continued to intensify rapidly as it moved westward away from Mexico.  It now has maximum sustained winds to 160 m.p.h. which makes it a Category 5 hurricane on the Saffir-Simpson Scale.  Marie is the first hurricane to reach Category 5 intensity over the Eastern North Pacific since Hurricane Celia in 2010.  Marie is a large hurricane and it is approximately half the size of Hurricane Sandy, but Marie is a symmetrical storm.  Hurricane force winds extend out 35-60 miles in all quadrants of Marie.  Marie is in a favorable environment with warm Sea Surface Temperatures and little vertical wind shear.  It could strengthen a little more or it may have attained its peak intensity.  Some satellite imagery suggests that a second eyewall may be forming and an eyewall replacement cycle would initially produce weakening followed possibly by fluctuations in intensity.

The Hurricane Intensity Index (HII) for Marie is 35.0.  The Hurricane Size Index (HSI) is 21.5.  The Hurricane Wind Intensity Size Index (HWISI) is 56.5.

Karina, Lowell and Marie

The atmosphere over the tropical Eastern North Pacific Ocean remains active with two hurricanes and a tropical storm.  Karina re-intensified into a hurricane about 1400 miles east of Hawaii.  It is moving slowly to the northeast as it is drawn into the large circulation around tropical storm Lowell.  Although the atmospheric conditions are allowing it to maintain hurricane force winds at the moment, it will encounter less favorable conditions as it moves farther north.

Tropical Storm Lowell is slowly spinning down about 1000 miles west of Baja California.  Lowell is moving slowly northwestward over cooler Sea Surface Temperatures (SSTs).  The SSTs are cool enough that Lowell is only generating lower clouds and it has not produced any deep thunderstorms in recent hours.  Lowell could be reclassified as a non-tropical low later today or tomorrow.  Lowell has a large circulation and it will take it a few days to spin down completely.

Hurricane Marie is intensifying rapidly about 330 miles south-southwest of Manzanillo, Mexico.  It currently has a maximum sustained wind speed of 85 m.p.h. and it could become a major hurricane during the next day or two.  Marie has a large well organized circulation and upper level divergence is well established over it.  It is expected to move northwestward parallel to the west coast of Mexico.  Marie is the 13th named tropical cyclone and 8th hurricane of the Eastern North Pacific 2014 season.

Tropical Storms Karina and Lowell and the Fujiwhara Effect

I am sometimes asked what happens when two tropical cyclones get close to each other.  The answer depends on the relative size and intensity of the two systems and how close they come to each other.  The Fujiwhara Effect is the name given to the tracks taken by the two vorticies.  If the two tropical cyclones are of nearly equal size and intensity, then they tend to move cyclonically around a center of rotation that is roughly half way between them.  If one cyclone is much bigger and stronger, then the center of rotation is shifted toward the bigger and stronger cyclone.

Tropical Storm Lowell has a large circulation and a maximum sustained wind speed of around 50 m.p.h.  Tropical Storm Karina is located about 700 miles to the west-southwest of Lowell.  Karina has a much smaller circulation and it also has a maximum sustained wind speed of 50 m.p.h.  Some of the models are forecasting that the two tropical storms will rotate around a point closer to Lowell than to Karina (i.e. the Fujiwara Effect).  This would result in Lowell moving general west-northwest and pass to the north of Karina.  The larger circulation of Lowell could also pull Karina back toward the east-northeast as Karina passes south of Lowell.  It is also possible that the circulation of Lowell could be so big that it captures Karina and Karina eventually gets absorbed by Lowell.