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.

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.

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.

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.

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.

More thunderstorms developed near the center of a slow moving area of low pressure south of Mexico and the National Hurricane Center classified the system as Tropical Storm Vance.  At 5:00 p.m. EDT the center of Vance was located at latitude 11.0°N and longitude 101.0°W which put it about 415 miles south of Acapulco, Mexico.  Vance was moving toward the west at 5 m.p.h.  The maximum sustained wind speed was 40 m.p.h. and the minimum surface pressure was 1005 mb.  Vance is the 20th named tropical cyclone for form over the Eastern North Pacific during 2014, which is the most since 1992.

Vance is being steered toward the west by an upper level ridge to its north.  Vance is expected to take a long, clockwise path as it moves around the western edge of the ridge.  Some recent guidance from numerical models suggests that Vance could move farther westward than was indicated in previous model forecasts.   Eventually, when Vance moves farther north, it is anticipated that it will be turned northeastward by a large trough off the west coast of North America.  The trough could pull Vance toward the west coast of Mexico sometime next week.

There are southwesterly winds blowing over the top of Vance in the upper levels and the result is that most of the thunderstorms are developing north and east of the center.  The shear is expected to decrease on Friday.  Vance will be moving over Sea Surface Temperatures (SSTs) that are warmer than 29°C.  So, there will be sufficient energy for intensification and some guidance is indicating that Vance could become a hurricane.   When the upper level trough begins to affect Vance, the wind shear will increase and it could be on a weakening trend when it turns toward the coast of Mexico next week.