Hurricane Simon intensified rapidly on Saturday and it is now a Major Hurricane.  At 5:00 p.m. EDT the center of Hurricane Simon was located at latitude 20.6°N and longitude 115.0°W which put it about 365 miles west-southwest of the southern tip of Baja California and about 495 miles south of Punta Eugenia, Mexico.  Simon was moving toward the west-northwest at 14 m.p.h.  The maximum sustained wind speed was 120 m.p.h. and the minimum surface pressure was 950 mb.

Simon is the 8th hurricane to reach Major Hurricane intensity over the Eastern North Pacific during 2014.  This ties the record for the most Major Hurricanes in one year in that basin, which was set previously in 1983, 1992 and 1993.

Simon is moving around the western edge of a ridge centered over northern Mexico.  It should turn more toward the north on Sunday.  As Simon moves farther north, it will eventually move toward the northeast.  It could approach Baja California by the middle of next week.

Simon may be on the threshold of an eyewall replacement cycle.  If it goes through one of those cycles, there will be some fluctuations in intensity.  When Simon moves west of Baja California it will move over cooler Sea Surface Temperatures and begin to weaken.  Simon is likely to be a weakening tropical cyclone when it nears Baja California.

Tropical Depression 18-E which formed earlier today has intensified into Tropical Storm Rachel.  At 11:00 p.m. EDT on Wednesday the center of Tropical Storm Rachel was located at latitude 15.3°N and longitude 107.4°W which put it about 325 miles southwest of Manzanillo, Mexico and about 550 miles south-southeast of the southern tip of Baja California.  Rachel was moving toward the west at 12 m.p.h.  The maximum sustained wind speed was 40 m.p.h. and the minimum surface pressure was 1004 mb.

A strong upper level ridge over northern Mexico has been producing northeasterly winds and wind shear over the circulation of Rachel.  The wind shear has been the reason why most of the thunderstorms have been located west of the center of circulation.  The northeasterly winds diminished slightly during recent hours and more thunderstorms developed closer to the center.  The improved organization allowed the wind speed at the surface to increase and Rachel became a tropical storm.  The upper level winds could decrease further and some additional intensification is possible.

A ridge in the middle levels is likely to steer Rachel to the west-northwest during the next day or two.  As Rachel moves farther north, it could be affected by a mid-level trough (i.e. a shortwave trough) in the westerly flow in about 72 hours.  If Rachel is strong enough and tall enough, then the mid-level trough could turn Rachel back to the northeast, which could move it toward Baja California.  If Rachel is weaker and the circulation does not extend as high into the atmosphere, then the mid-level trough may not affect the movement of Rachel.  In that case, it would probably continue to move west and dissipate over cooler Sea Surface Temperatures.

Tropical Storm Polo continues to move northwestward parallel to the west coast of Mexico.  At 11:00 p.m. EDT on Thursday the center of Polo was located at latitude 18.4°N and longitude 106.6°W which put it about 150 miles south-southwest of Cabo Corrientes, Mexico and about 375 miles southeast of the southern tip of Baja California.  Polo was moving toward the northwest at 9 m.p.h.  The maximum sustained wind speed was 70 m.p.h. and the minimum surface pressure was 981 mb.

An upper level ridge over northwestern Mexico is producing northeasterly winds that are creating wind shear over Polo.  The wind shear is limiting thunderstorm activity on the northern side of the storm.  It is also possible that Polo is close enough to Mexico that it may be pulling some drier air into the northern half of the circulation.  Both of those factors are inhibiting intensification of Polo.

A high pressure system in the middle levels over Mexico is steering Polo toward the northwest.  The tropical storm is starting to move a little more quickly.  Numerical models are suggesting that the mid-level high will strengthen and eventually turn Polo more toward the west.  Most guidance predicts that Polo will move southwest of Baja California.  However, based on the faster motion the government of Mexico has issued a Tropical Storm Watch for a portion of southern Baja California from Santa Fe to La Paz.  A Tropical Storm Warning remains in effect for a portion of the coast from Punta San Telmo to Playa Perula.  A Tropical Storm Watch continues for the portion of the coast from Playa Perula to Cabo Corrientes.

The circulation around Polo continues to exhibit increasing signs of intensification and it was upgraded to hurricane status on Wednesday night.  Polo is the sixteenth named tropical cyclone to form over the Eastern North Pacific Ocean during 2014 and it is the eleventh to reach hurricane intensity.

At 11:00 p.m. EDT on Wednesday the center of Hurricane Polo was located at latitude 16.4°N and longitude 104.6°W which put it about 180 miles south of Manzanillo, Mexico.  Polo was moving toward the west-northwest at 10 m.p.h.  The maximum sustained wind speed was 75 m.p.h. and the minimum surface pressure was 988 mb.

The movement of Polo has varied as the circulation has tightened around the core and more well defined spiral bands have developed.  In recent hours it has exhibited a more west-northwesterly motion after moving more toward the northwest earlier in the day.  Polo appears to be being steered mostly by an upper level high over Mexico.  The upper level high should steer Polo on a track that is roughly parallel to the west coast of Mexico.  Many of the numerical models are predicting that Polo will pass southwest of Baja California, but as Hurricane Odile showed, it could take a track closer to the coast.

Polo is moving over warm Sea Surface Temperatures and further intensification is likely.  As the organization of the circulation increases and an eye forms, a period of more rapid intensification is possible.

The government of Mexico has issued a Tropical Storm Warning for the portion of the coast from Punta San Telmo to Playa Perula.  A Tropical Storm Watch has been issued for the portion of the coast from Playa Perula to Cabo Corrientes.

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.

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.