Tropical Depression Two-E Strengthens to Tropical Storm Blanca

Despite vertical wind shear caused by the outflow from Hurricane Andres, the low level circulation of Tropical Depression Two-E continued to consolidate and the National Hurricane Center upgraded the system to Tropical Storm Blanca.  At 11:00 a.m. EDT on Monday the center of Tropical Storm Blanca was located at latitude 13.5°N and longitude 104.1°W which put it about 335 miles (540 km) south-southwest of Zihuatanejo, Mexico.  Blanca was moving toward the northwest at 5 m.p.h. (7 km/h).  The maximum sustained wind speed was 40 m.p.h. (65 km/h) and there were gusts to 50 m.p.h. (80 km/h).  The minimum surface pressure was 1004 mb.

Upper level divergence from Hurricane Andres, which is about 1000 miles west of Blanca, is still generating some vertical wind shear over the top of Blanca.  However, the strongest upper level outflow and wind shear is now several hundred miles north of the tropical storm.  As a result, Blanca has been able to efficiently extract energy from the upper ocean and it has generated many more thunderstorms in recent hours.  The circulation has developed spiral bands and an inner core of convection.  The strong thunderstorms near the core appear to be generating some upper level outflow which is pumping out mass and causing the surface pressure to decrease.  Blanca is over water where the Sea Surface Temperature is near 30°C and there is a lot of energy in the upper ocean.  Blanca is likely to intensify and it could intensify rapidly if the magnitude of the wind shear remains moderate or low.

Blanca is being steered slowly toward the northwest by a ridge over northern Mexico, but the steering currents are relatively weak.  The ridge is expected to strengthen during the week and steer Blanca toward the northwest or north-northwest.  On its anticipated track Blanca poses no immediate threat to Mexico.  However, it could approach Baja California or the western coast of Mexico later this week.

Andres Strengthens Into a Category 4 Hurricane

Hurricane Andres turned westward and strengthened rapidly into a Major Hurricane on Sunday.  At 11:00 p.m. EDT on Sunday the center of Hurricane Andres was located at latitude 15.3°N and longitude 119.2°W which put it about 800 miles southwest of the southern tip of Baja California.  Andres was moving toward the west at 6 m.p.h.  The maximum sustained wind speed was 140 m.p.h. (220 km/h) which made Andres a Category 4 hurricane on the Saffir-Simpson Scale.  There were gusts to 165 m.p.h. (265 km/h) and the minimum surface pressure was 943 mb.   Andres became only the fifth Major Hurricane to form over the Eastern North Pacific during the month of May.

By turning toward the west Hurricane Andres remained over water where the Sea Surface Temperature (SST) was 27°C.  The westward movement also minimized the vertical wind shear.  The combination of warm SST and little vertical wind shear produced rapid intensification.  Andres could remain over warm SSTs for another day or so.  Eventually it will encounter cooler water, which will be unable to supply enough energy to maintain its current intensity.  There are stronger upper level winds west of Andres and those will increase the vertical wind shear over the hurricane.  Cooler SSTs and more shear will weaken Andres during the coming week.

A strengthening ridge steered Andres toward the west on Sunday.  Another upper level trough will approach the ridge during the next few days.  The trough is likely to weaken the ridge and cause Andres to turn more northward again.  Track guidance from the numerical models diverges later in the week and the uncertainty increases at longer time periods.

Tropical Depression Two-E Forms West of Mexico

Thunderstorms developed near a low level circulation on Sunday evening and the National Hurricane Center classified the system as Tropical Depression Two-E (TD2E).  At 11:00 p.m. EDT on Sunday the center of TD2E was located at latitude 12.7°N and longitude 103.3°W which put it about 365 miles south-southwest of Zihuatanejo, Mexico.  TD2E was moving toward the west-northwest at 5 m.p.h.  The maximum sustained wind speed was 35 m.p.h. (55 km/h) and there were gusts to 45 m.p.h. (70 km/h).  The minimum surface pressure was 1006 mb.

The intensity forecast for TD2E is quite challenging.  Upper level outflow from Hurricane Andres, which is about 1000 miles west of TD2E, is creating strong vertical wind shear over the top of the depression.  The low level circulation of TD2E was completely exposed at times on Sunday afternoon as the higher level clouds were blown away from it.  At other times thunderstorms developed quickly near the center of circulation.  As long the outflow from Andres blows over the top of TD2E, it will inhibit intensification.  On the other hand, the depression is over water where the Sea Surface Temperature (SST) is near 30°C and there is a lot of energy in the upper layer of the ocean.  Hurricane Andres is likely to weaken and move farther away from TD2E during the next few days.  If that happens, then the vertical wind shear over TD2E will decreases.  If the lower level structure of the depression is still intact at that time, then it will be able to extract energy from the ocean and intensify.  Guidance from numerical models predicts TD2E will survive and intensify later this week.

The track forecast is also challenging because it is partly dependent on the vertical height of the structure of the depression.  If the depression is weak and shallow, it will be steered more by winds in the lower levels.  Those winds would tend to steer it toward the west-northwest.  If the depression intensifies and grows taller, it will be steered by winds higher in the atmosphere.  Fluctuations in the amount of vertical wind shear and its subsequent effects on the intensity of TD2E could result in erratic motion for several days.

Andres Gets Close To Major Hurricane Status

Hurricane Andres strengthened quickly on Saturday and it came close to reaching Major Hurricane status.  At 11:00 p.m. EDT on Saturday the center of Hurricane Andres was located at latitude 15.1°N and longitude 116.8°W which put it about 700 miles southwest of the southern tip of Baja California.  Andres was moving toward the northwest at 7 m.p.h. (11 km/h).  The maximum sustained wind speed was 110 m.p.h. (175 km/h) and there were gusts to 130 m.p.h. (210 km/h).  The minimum surface pressure was 966 mb.

The convection near the center of Hurricane Andres continued to strengthen for much of Saturday and the eye exhibited circular symmetry.  The hurricane was moving over water where the Sea Surface Temperature (SST) was near 28°C and there was sufficient energy in the upper ocean to support a strong hurricane.  The upper level winds were relatively light and there was not much vertical wind shear over the center of circulation.  However, Andres may be near its maximum intensity.  There are cooler SSTs to the northwest of the hurricane and it will gradually move over those cooler SSTs.  As it moves over cooler water, Andres will also pull cooler, more stable air into the northwestern part of the circulation.  Cooler water and more stable air are likely to weaken the circulation on Sunday.   There are also stronger upper level westerly winds near latitude 20°N and so Andres will encounter stronger vertical wind shear early next week, which could speed its weakening trend.

A trough passing north of the ridge that has been steering Andres has weakened the ridge and caused the hurricane to turn toward the northwest.  Once the trough moves farther east, the ridge will strengthen and extend westward.  The building ridge will cause Andres to move more toward the west during the early part of next week.  On its anticipated track Andres poses no threat to Mexico.

Andres Intensifies Into a Hurricane

The core of the circulation of Andres became more circular and symmetrical on Friday and an eye has been visible intermittently during the day.  The National Hurricane Center classified Andres as a hurricane in its 5:00 p.m. EDT advisory on Friday.  At that time the center of Hurricane Andres was located at latitude 12.8°N and longitude 114.8°W which put it about 770 miles south-southwest of the southern tip of Baja California, Mexico.  Andres was moving toward the northwest at 7 m.p.h.  The maximum sustained wind speed was 75 m.p.h. and there were wind gusts to 90 m.p.h.  The minimum surface pressure was 990 mb.

As the circulation consolidated in the center of Andres strong thunderstorms pushed higher into the atmosphere around the eye.  Those thunderstorms pumped mass away from the center and caused the pressure at the surface to decrease.  Andres is over water where the Sea Surface Temperature (SST) is between 28°C and 29°C which means there is enough energy in the upper ocean to support further intensification.  It also remains in an area where the vertical wind shear is low.  So, further intensification is likely during the next day or two.  As Andres moves farther north, it will gradually move over cooler SSTs and when it gets near latitude 20°N it will begin to be affected by upper level southwesterly winds.  Cooler SSTs and more wind shear will likely cause Andres to weaken during the early part of next week.

Andres is near a weakness in the mid-level ridge that has been steering the hurricane.  The weakness in the ridge caused Andres to turn toward the northwest and its forward speed to decrease.  After an upper level trough moves east of the ridge in a day or two, the ridge will strengthen and extend westward.  That will cause Andres to move more toward the west again.  On its anticipated track Andres poses no threat to Mexico.

TD One-E Intensifies Quickly Into Tropical Storm Andres

A favorable environment caused Tropical Depression One-E to intensify quickly into Tropical Storm Andres on Thursday.  At 11:00 p.m. EDT on Thursday the center of Tropical Storm Andres was located at latitude 11.8°N and longitude 113.3°W which put it about 800 miles south-southwest of the southern tip of Baja California.  Andres was moving toward the west-northwest at 10 m.p.h.  The maximum sustained wind speed was 70 m.p.h. and there were gusts to 85 m.p.h.  The minimum surface pressure was 994 mb.

Andres exhibits a more organized circulation pattern on satellite imagery.  The end of the primary rainband wrapped completely around the center of circulation and an eye appears on some satellite images.  There are more thunderstorms in the rainbands and upper level outflow continues in all directions.  Andres is moving over water where the Sea Surface Temperature (SST) is near 29°C.  Although there are strong upper level westerly winds north of 20°N and brisk upper level easterly winds near the Equator, Andres is moving through a region where the upper level winds are light.  There is little vertical wind shear to inhibit the  intensification of Andres during the next day or so.  It will gradually move over water where the SSTs are slightly cooler, but there should still be plenty of energy in the upper ocean to support further intensification.  Andres is likely to become a hurricane on Friday and it could continue to intensify rapidly for another 12 to 24 hours.

An upper level trough passing well to the north of Andres is weakening the ridge that has been steering Andres toward the west-northwest.  The effect of the trough will likely be to slow the forward motion of Andres and temporarily make it move more toward the northwest.  After the upper level trough moves off to the northeast, the ridge is likely to strengthen again.  As the ridge strengthens, it will start to steer Andres more toward the west.  On its projected track Andres poses no current threat to Mexico.

 

Tropical Depression One-E Forms Southwest of Mexico

A well developed cyclonic circulation formed at the surface in a large area of thunderstorms southwest of Mexico and the National Hurricane Center classified the system as Tropical Depression One-E.  At 5:00 a.m. EDT on Thursday the center of Tropical Depression One-E (TD1E) was located at latitude 11.0°N and longitude 110.4°W which put it about 685 miles southwest of Manzanillo, Mexico.  TD1E was moving toward the west-northwest at 15 m.p.h.  The maximum sustained wind speed was 35 m.p.h. and there were gusts to 45 m.p.h.  The minimum surface pressure was 1005 mb.

The circulation around TD1E is still in the organizational stage and there are more strong thunderstorms in the southern half of the circulation.  TD1E is in an environment that is very favorable for intensification.  It is moving over water where the Sea Surface Temperatures (SSTs) are around 29°C to 30°C.  It is an area between upper level easterly winds near the Equator and stronger upper level westerly winds farther north.  There are lighter upper level winds over TD1E and the light winds allowed it to develop strong upper level outflow in all directions.  Warm SSTs and strong upper level divergence should allow TD1E to intensify during the next several days and a period of rapid intensification is quite possible once the circulation is fully organized.

An upper level ridge to the northeast of TD1E is steering it toward the west-northwest.  As TD1E gets closer to a weakness in the western portion of the ridge, it is expected to turn toward the northwest and slow down.  On its anticipated path TD1E poses no immediate threat to the west coast of Mexico.

Typhoon Dolphin Is Bringing Wind and Heavy Rain to Iwo To

Even though the center of Typhoon Dolphin is still over 100 miles from Iwo To, it is bringing wind and heavy rain to that island.  The most recent surface observation reported southeast winds at 43 m.p.h. with gusts to 66 m.p.h.  At 11:00 p.m. EDT on Monday the center of Typhoon Dolphin was located near latitude 24.6° and longitude 139.7°E which put it about 140 miles west-southwest of Iwo To.  Dolphin was moving toward the northeast at 10 m.p.h.  The maximum sustained wind speed was 85 m.p.h. and there were gusts to 105 m.p.h.  The minimum surface pressure was 967 mb.

Dolphin will continue to move over cooler Sea Surface Temperatures as it moves farther north.  It will also encounter strong upper level westerly winds, which will increase vertical wind shear.  So, Typhoon Dolphin will weaken steadily on Tuesday.  It will eventually transition into an extratropical cyclone as it passes southeast of Japan.

Upper level westerly winds are steering Typhoon Dolphin toward the northeast.  It is expected to accelerate toward the northeast on Tuesday.  On its anticipated track the center of Dolphin will pass northwest of Iwo To during the next few hours.  It could pass very near Chichi Jima on Tuesday and bring strong wind and heavy rain.

Typhoon Dolphin Approaching Iwo To

Although Typhoon Dolphin is weakening, it will still be a typhoon when it approaches Iwo To in about 24 hours.  At 11:00 p.m. EDT on Sunday the center of Typhoon Dolphin was located at latitude 21.3°N and longitude 138.7°E which put it about 320 miles south-southwest of Iwo To.  Dolphin was moving toward the north at 10 m.p.h.  The maximum sustained wind speed was 125 m.p.h. and there were gusts to 155 m.p.h.  The minimum surface pressure was 941 mb.

Upper level westerly winds blowing over the top of Dolphin are tilting the circulation to the east and contributing to the weakening of the typhoon.  Dolphin will soon be moving over water where the Sea Surface Temperature (SST) is lower than 26°C and as it moves farther north it will encounter stronger upper level westerly winds.  Cooler SSTs and more vertical wind shear will continue to weaken Dolphin.  As it moves into a cooler environment southeast of Japan in several days, Dolphin will make a transition to an extratropical cyclone.

Dolphin is moving around the the western end of a subtropical ridge.  It will gradually turn more toward the northeast on Monday.  As it encounters stronger westerly winds, Dolphin will start to move more rapidly toward the northeast.  On its anticipated track, Dolphin will near Iwo To in about 24 hours.  Although it will be weaker, it will still be a typhoon at that time.

 

Typhoon Dolphin Becomes Equivalent of Category 5 Hurricane

Typhoon Dolphin intensified rapidly on Saturday and it reached an intensity equivalent to a Category 5 hurricane on the Saffir-Simpson Scale.  At 11:00 p.m. EDT on Saturday the center of Typhoon Dolphin was located at latitude 18.3°N and longitude 139.0E which put it about 470 miles south-southwest of Iwo To.  Dolphin was moving toward the northwest at 12 m.p.h.  The maximum sustained wind speed was 160 m.p.h. and there were gusts to 195 m.p.h.  The minimum surface pressure was 918 mb.

Dolphin is moving over water where the Sea Surface Temperatures (SSTs) are between 26°C and 27°C.  It is in an area where the upper level winds are light and there is not much vertical wind shear.  It has very well developed upper level outflow, especially on the northeast side of the circulation.  Dolphin developed concentric eyewalls earlier on Saturday, but the inner eyewall appears to have dissipated.  The circulation has consolidated around the outer eyewall and it is now the core of the circulation.  Dolphin is probably near its peak intensity.  As it moves farther north, the SSTs will decrease and it will move over water cooler than 26°C.    In addition, upper level westerly winds will increase as the typhoon moves north of 25°N.  Cooler SSTs and more vertical wind shear will produce a steady weakening of Dolphin as it moves north.

Dolphin is moving around the western end of a subtropical ridge.  It is likely to move northward on Sunday and then turn to the northeast on Monday.  As it encounters westerly winds early next week, it is likely to accelerate toward the northeast.  On its anticipated track Dolphin will approach Iwo To in about 48 hours.  It could still be a significant typhoon at that time.