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Tropical Storm Rosa Nears Baja California

Tropical Storm Rosa moved nearer to Baja California on Monday morning.  At 11:00 a.m. EDT on Monday the center of Tropical Storm Rosa was located at latitude 27.5°N and longitude 116.5°W which put it about 90 miles (145 km) west-southwest of Punta Eugenia, Mexico.  Rosa was moving toward the north-northeast at 12 m.p.h. (19 km/h).  The maximum sustained wind speed was 45 m.p.h. (75 km/h) and there were wind gusts to 60 m.p.h. (95 km/h).  The minimum surface pressure was 1000 mb.

A Tropical Storm Warning was in effect for the portion of the coast from Punta Abreojos to Cabo San Quintin, Mexico.  A Tropical Storm Watch was in effect for the portion of the coast from Bahia de los Angeles to San Felipe, Mexico.

Tropical Storm Rosa was weakening as it approached the coast of Baja California.  Rosa was moving over water where the Sea Surface Temperature was near 23°C.  An upper level low west of California was producing southwesterly winds which were blowing toward the top of the circulation.  Those winds were causing significant vertical wind shear.  The effects of cool water and vertical shear were causing most of the stronger thunderstorms to occur northeast of the center of circulation.  Bands south and west of the center consisted primarily of showers and lower clouds.

The center of Tropical Storm Rosa will reach northern Baja California in a few hours.  Rosa will bring some gusty winds when when it reaches the coast, but the greater risk is locally heavy rainfall.  Rosa could drop several inches of rain and flash floods could occur.  The lower level part of Rosa’s circulation will weaken when it crosses Baja California.  However, the upper low west of California will steer the middle and upper parts of Tropical Storm Rosa over the Southwestern U.S.  Rosa, or its remnants, could drop locally heavy rain over that region during the next several days.  Flash Flood Watches have been issued for southeastern California, eastern Nevada, western Arizona, and much of Utah.

Elsewhere over the Eastern North Pacific, Tropical Storm Sergio was strengthening slowly south of Baja California.  At 11:00 a.m. EDT on Monday the center of Tropical Storm Sergio was located at latitude 11.5°N and longitude 109.5°W which put it about 790 miles (1275 km) south of the southern tip of Baja California.  Sergio was moving toward the west at 14 m.p.h. (22 km/h).  The maximum sustained wind speed was 70 m.p.h. (110 km/h) and there were wind gusts to 85 m.p.h. (135 km/h).  The minimum surface pressure was 995 mb.

Hurricane Rosa Moves Toward Baja California

Hurricane Rosa moved toward Baja California on Saturday night.  At 11:00 p.m. EDT on Saturday the center of Hurricane Rosa was located at latitude 22.4°N and longitude 118.9°W which put it about 440 miles (710 km) south-southwest of Punta Eugenia, Mexico.  Rosa was moving toward the north at 12 m.p.h. (19 km/h).  The maximum sustained wind speed was 100 m.p.h. (160 km/h) and there were wind gusts to 120 m.p.h. (195 km/h).  The minimum surface pressure was 969 mb.

A Tropical Storm Warning was in effect for the portion of the coast from Punta Abreojos to Cabo San Quintin, Mexico.  A Tropical Storm Watch was in effect for the portion of the coast from Bahia de los Angeles to San Felipe, Mexico.

Hurricane Rosa will move into an environment unfavorable for hurricanes on Sunday.  Rosa will move over water where the Sea Surface Temperature is cooler than 26°C.  In addition an upper level low near the west coast of the U.S. will produce southwesterly winds which will cause vertical wind shear.  The combination of cooler water and more vertical wind shear will cause Hurricane Rosa to weaken.  Rosa could weaken to a tropical storm by Sunday night.

The upper low will steer Hurricane Rosa toward the northeast during the next several days.  On its anticipated track Rosa could reach Baja California on Monday.  It will likely be a tropical storm at that time.  Even though it will weaken, Rosa will drop heavy rain over parts northern Baja California and the southwestern U.S.  The heavy rain could cause flash floods.

Elsewhere over the Eastern North Pacific Ocean Tropical Storm Sergio formed southwest of Acapulco, Mexico.  At 11:00 p.m. EDT on Saturday the center of Tropical Storm Sergio was located at latitude 12.3°N and longitude 103.3°W which put it about 390 miles (630 km) southwest of Acapulco, Mexico.  Sergio was moving toward the west at 10 m.p.h. (16 km/h).  The maximum sustained wind speed was 45 m.p.h. (75 km/h) and there were wind gusts to 60 m.p.h. (95 km/h).  The minimum surface pressure was 1003 mb.

Hurricane Rosa Rapidly Intensifies Into a Major Hurricane Southwest of Baja California

Hurricane Rosa rapidly intensified into a major hurricane southwest of Baja California on Thursday.  At 5:00 p.m. EDT on Thursday the center of Hurricane Rosa was located at latitude 16.9°N and longitude 115.9°W which put it about 570 miles (915 km) southwest of the southern tip of Baja California.  Rosa was moving toward the west at 10 m.p.h. (16 km/h).  The maximum sustained wind speed was 125 m.p.h. (200 km/h) and there were wind gusts to 145 m.p.h. (240 km/h).  The minimum surface pressure was 953 mb.

Hurricane Rosa rapidly intensified into a powerful hurricane on Thursday and a circular eye developed at the center of circulation.  The eye was surrounded by a ring of strong thunderstorms and the strongest winds were occurring in the ring of storms.  The circulation around Hurricane Rosa was symmetrical.  Several bands of showers and thunderstorms were revolving around the core of the hurricane.  Storms around the core were generating strong upper level divergence which was pumping mass away from the hurricane.

The circulation around Hurricane Rosa was relatively small.  Winds to hurricane force only extended out about 35 miles (55 km) from the center of circulation.  Winds to tropical storm force extended out about 115 miles (185 km) from the center.  The Hurricane Intensity Index (HII) for Hurricane Rosa was 23.6.  The Hurricane Size Index (HSI) was 9.8 and the Hurricane Wind Intensity Size Index (HWISI) was 33.4.

Hurricane Rosa will continue to move through an environment favorable for intensification during the next 12 to 24 hours.  Rosa will move over water where the Sea Surface Temperature is near 28°C.  It will move through an area where the upper level winds are weak and there will be little vertical wind shear during the shorter term.  If a rainband wraps around the existing eye and eyewall, an eyewall replacement cycle could halt the current period of rapid intensification.  Hurricane Rosa will start to move over cooler water during the weekend.  An upper level low west of California will produce southwesterly winds which will blow toward the top of Rosa’s circulation.  Those winds will cause more vertical wind shear and they could cause Rosa to weaken more quickly.

Hurricane Rosa will move around the western end of a ridge of high pressure over northern Mexico on Friday.  Rosa will start to move more toward the north when it moves around the western end of the ridge.  The upper level trough east of California will turn Rosa more toward the northeast during the weekend.  On its anticipated track Rosa could approach Baja California early next week.  It may weaken to a tropical storm before it gets to Baja California, but it still will have the potential to drop heavy rain.

Hurricane Bud Weakens, Watch Issued for Baja California

Hurricane Bud weakened significantly on Tuesday, but it prompted the issuance of a Tropical Storm Watch for the southern portion of Baja California.  At 11:00 p.m. EDT on Tuesday the center of Hurricane Bud was located at latitude 18.7°N and longitude 108.6°W which put it about 300 miles (485 km) south-southeast of Cabo San Lucas, Mexico.  Bud was moving toward the north-northwest at 3 m.p.h. (5 km/h).  The maximum sustained wind speed was 90 m.p.h. (150 km/h) and there were wind gusts to 105 m.p.h. (170 km/h).  The minimum surface pressure was 973 mb.  The government of Mexico issued a Tropical Storm Watch for the portion of the coast from Santa Fe to La Paz, Mexico including Cabo San Lucas.

Hurricane Bud weakened to a Category 1 hurricane on the Saffir-Simpson Scale on Tuesday.  The center of Hurricane Bud was over water where the Sea Surface Temperature was near 27°C, but much of the northern half of the circulation was over cooler water.  The slow movement of Bud may have also allowed the winds to mix cooler water to the surface.  Thunderstorms were not as tall and the bands in the northern half of the circulation consisted primarily of showers and low clouds.  The stronger thunderstorms were occurring mainly south and east of the center of Hurricane Bud.

Hurricane Bud is forecast to spin down slowly during the next several days.  Cooler water at the surface of the ocean is not likely to supply sufficient energy to maintain the circulation.  The upper level winds are weak and there is little vertical wind shear, but the lack of shear will be less important than effects of the cooler water.  The lack of stronger thunderstorms in the northern half of the circulation will limit the downdrafts that could transport stronger winds to the surface.  Hurricane Bud could weaken to a tropical storm on Wednesday if new thunderstorms do not form in the core of the circulation.

A ridge in the middle troposphere over the southwestern U.S. almost blocked the forward motion of Hurricane Bud on Tuesday.  Bud moved slowly toward the north-northwest.  A slow motion toward the north-northwest is forecast to continue for another 24 to 36 hours.  After that time a trough over the Pacific Ocean is forecast to push the ridge eastward.  When the trough approaches, stronger southerly winds will steer Bud northward more quickly.  On its anticipated track Bud is forecast to approach the southern tip of Baja California in 36 to 48 hours.

Hurricane Bud is likely to be a tropical storm when it nears Baja California.  Bud will bring gusty winds, but the bigger risk will be locally heavy rain.  Heavy rain falling on steep terrain could cause flash floods.  Bud or its remnants could also bring rain to parts of the southwestern U.S.

Tropical Storm Pilar Forms Near Mexico

Tropical Storm Pilar formed just west of Mexico on Saturday.  At 11:00 p.m. EDT on Saturday the center of Tropical Storm Pilar was located at latitude 18.7°N and longitude 105.3°W which put it about 120 miles (195 km) south-southeast of Cabo Corrientes, Mexico.  Pilar was moving toward the north at 5 m.p.h. (8 km/h).  The maximum sustained wind speed was 40 m.p.h. (65 km/h) and there were wind gusts to 50 m.p.h. (80 km/h).  The minimum surface pressure was 1003 mb.

A Tropical Storm Warning was issued for the portion of the coast from Manzanillo to El Roblito including the Islas Marias.

A distinct center of circulation developed within a larger area of low pressure near the west coast of Mexico on Saturday and the system was classified as Tropical Storm Pilar.  Several bands of showers and thunderstorms began to form around the center.  Storms near the center started to generate upper level divergence which was pumping mass away to the west of Tropical Storm Pilar.

Tropical Storm Pilar will move through an environment that will be somewhat favorable for intensification on Sunday.  Pilar will move over water where the Sea Surface Temperature is near 29°C.   An upper level high over Mexico is producing easterly winds which are blowing toward the top of the circulation.  Those winds are producing some vertical wind shear, but the shear was not strong enough to prevent the formation of Tropical Storm Pilar.  The eastern part of the circulation will be moving over western Mexico and increased friction will be the primary factor inhibiting strengthening.  Tropical Storm Pilar is likely to intensify on Sunday.

A ridge in the middle levels of the atmosphere over Mexico is steering Tropical Storm Pilar slowly toward the north.  On its anticipated track the center of Tropical Storm Pilar will be very near Cabo Corrientes on Sunday night.  The center could move inland or it could remain just west of the coast.  Tropical Storm Pilar will drop very heavy rain over parts of the states of Colima and Jalisco.  The heavy rain could cause flash flooding in some locations.

Max Rapidly Intensifies Into a Hurricane Near Acapulco

Tropical Storm Max intensified rapidly into a hurricane on Thursday morning.  At 11:00 a.m. EDT on Thursday the center of Hurricane Max was located at latitude 16.3°N and longitude 99.9°W which put it about 40 miles (65 km/h) south of Acapulco, Mexico.  Max was moving toward the east at 7 m.p.h. (11 km/h).  The maximum sustained wind speed was 80 m.p.h. (130 km/h) and there were wind gusts to 95 m.p.h. (155 km/h).  The minimum surface pressure was 988 mb.

A Hurricane Warning was in effect for the portion of the coast from Zihuatenajo to Punta Maldonado, Mexico.  A Tropical Storm Warning was in effect for the portion of the coast from Punta Maldonado to Laguas de Chacahua, Mexico.

The circulation of Hurriane Max is quite small.  Winds to hurricane force only extend out about 15 miles (25 km) from the center of circulation.  Winds to tropical storm force extend out about 50 miles (80 km) from the center.  Although the circulation of Hurricane Max is small, it is very well organized.  There is a small circular eye at the center of circulation.  The eye is surrounded by a ring of strong thunderstorms and the strongest winds are occurring in that ring of storms.

The center of Hurricane Max is very close to the coast of Mexico.  The outer fringes of the northwestern part of the circulation could already be pulling in some drier air.  Max will make landfall on the coast of Mexico within a few hours and it will start to dissipate as soon as the center make landfall.

The core of Hurricane Max will be capable of causing localized wind damage.  Max will also drop very heavy rain over parts of the states or Guerrero and Oaxaca and flash floods could occur in some areas of steeper terrain.

Elsewhere over the Eastern North Pacific Ocean, Tropical Storm Norma formed to the west of Hurricane Max.  At 11:00 a.m. EDT on Thursday the center of Tropical Storm Norma was located at latitude 17.2°N and longitude 109.5°W which put it about 395 miles (635 km) south of Cabo San Lucas, Mexico.  Norma was moving toward the north at 5 m.p.h. (8 km/h).  The maximum sustained wind speed was 40 m.p.h. (65 km/h) and there were wind gusts to 50 m.p.h. (80 km/h).  The minimum surface pressure was 1004 mb.  Tropical Storm Norma is forecast to strengthen and move toward Baja California.  Normal could be a hurricane when it approaches southern Baja California in a few days.

Tropical Storm Lidia Weakens, Still Raining on Baja California

Tropical Storm Lidia has weakened but it is producing rain over Baja California.  At 2:00 p.m. EDT on Saturday the center of Tropical Storm Lidia was located at latitude 28.3°N and longitude 114.6°W which put it about 40 miles (65 km) northeast of Punta Eugenia, Mexico.  Lidia was moving toward the northwest at 12 m.p.h. (19 km/h).  The maximum sustained wind speed was 40 m.p.h. (65 km/h) and there were wind gusts to 50 m.p.h. (80 km/h).  The minimum surface pressure was 999 mb.

A Tropical Storm Warning is in effect for the portion of the coast from Punta Abreojos to San Jose de Las Palomas, from Mulege to Isla San Luis and from Guaymas to Puerto Libertad, Mexico.

Tropical Storm Lidia weakened during the past 24 hours as it slowly moved northwest over Baja California.  There are some indications that the upper portion of the circulation may have decoupled from the lower half of Tropical Storm Lidia.  The upper portion of the circulation appears to be over the Gulf of California.  There are stronger thunderstorms over the Gulf of California because the Sea Surface Temperature is near 32°C in that body of water.  Those thunderstorms are producing heavy rain over parts of the eastern side of Baja California and the western part of Mexico adjacent to the Gulf of California.  The lower level center appears to be located northeast of Punta Eugenia over the Pacific Ocean just west of Baja California.  There are showers and thunderstorms near the low level center and they are dropping heavy rain in that area.  The potential for flash floods still exists in the areas where heavy rain is falling.

The low level center of Tropical Storm Lidia is forecast to continue to move toward the northwest.  Lidia will continue to weaken because the low level center is moving over water where the Sea Surface Temperature is near 23°C.  It will take several more days for the low level center to spin down and it could still produce locally heavy rain over the northern part of Baja California during that time.  The upper level portion of the circulation will likely be absorbed by the larger scale environmental flow in those levels.  Some clouds and moisture in the upper levels could flow over the southwestern U.S.

Tropical Storm Lidia Brings Wind and Heavy Rain to Baja California

Tropical Storm Lidia brought gusty winds and very heavy rain to Baja California on Thursday night.  At 11:00 p.m. EDT on Thursday the center of Tropical Storm Lidia was located at latitude 23.3°N and longitude 110.4°W which put it about 40 miles (65 km) northwest of Cabo San Lucas, Mexico.  Lidia was moving toward the north-northwest at 4 m.p.h. (6 km/h).  The maximum sustained wind speed was 65 m.p.h. (105 km/h) and there were wind gusts to 80 m.p.h. (130 km/h).  The minimum surface pressure was 991 mb.

A Hurricane Watch was in effect for the portion of the coast from Puerto Cortes to La Paz, Mexico including Cabo San Lucas.  A Tropical Storm Warning was in effect for the portion of the coast from Punta Eugenia to Bahia San Juan Bautista including Cabo San Lucas and from Bahia Tempehuaya to Bahia Kino.  A Tropical Storm Watch was in effect for the portion of the coast from Punta Eugenia to San Juan de Las Palomas and from Bahia San Juan Bautista to Isla San Luis and from Bahia Kino to Puerto Libertad.

Tropical Storm Lidia intensified as it approached the southern tip of Baja California on Thursday.  Several bands of showers and thunderstorms wrapped around the center of circulation and a partial eyewall appeared to form.  The airport at Cabo San Lucas reported sustained winds of 58 m.p.h. (83 km/h) and a Mexican automated station reported a sustained wind of 70 m.p.h. (113 km/h) and gusts to 90 m.p.h. (145 km/h) at a height of 735 feet (244 meters).  Tropical Storm Lidia has a large circulation.  Winds to tropical storm force extend out about 185 miles (295 km) from the center of circulation.

The large size of Tropical Storm Lidia meant that it was bringing tropical storm winds to the southern part of Baja California and parts of the west coast of Mexico.  Lidia was also producing very heavy rain over Baja California.  Flash floods are likely in places where steep terrain causes water to run off quickly.

Tropical Storm Lidia is forecast to move slowly north-northwest over Baja California.  The slow motion will prolong the period of gusty winds.  It will also cause the rain totals to be higher and increase the risk for floods.  Much of the circulation will remain over water and the large size of Lidia will mean that the tropical storm will weaken slowly.

Tropical Storm Lidia Threatens Baja California

Tropical Storm Lidia became an increased threat to Baja California as it moved closer on Wednesday night.  At 11:00 p.m. EDT on Wednesday the center of Tropical Storm Lidia was located at latitude 20.7°N and longitude 109.2°W which put it about 160 miles (255 km) south-southeast of the southern tip of Baja California.  Lidia was moving toward the north-northwest at 7 m.p.h. (11 km/h).  The maximum sustained wind speed was 40 m.p.h. (65 km/h) and there were wind gusts to 50 m.p.h. (80 km/h).  The minimum surface pressure was 1001 mb.

A Hurricane Watch is in effect for the portion of the coast from Puerto Cortes to La Paz, Mexico including Cabo San Lucas.  A Tropical Storm Warning is in effect for the portion of the coast from Puerto Cortes to San Evaristo including Cabo San Lucas and from Tempehuaya to Huatabampito, Mexico.  A Tropical Storm Watch is in effect for the portion of the coast from San Evaristo to Loreto, Mexico and from Puerto Cortes to Puerto Andresito.

A distinct center of circulation began consolidating in a large area of low pressure previously designated Potential Tropical Cyclone Fourteen-E on Wednesday.  Numerous bands of showers and thunderstorms started developing around the consolidating center.  There were more showers and thunderstorms in the southern half of the circulation than there were in the northern half of the circulation.  Thunderstorms southwest of the center of circulation were beginning to generate some upper level divergence, but it was not well developed.  Tropical Storm Lidia formed out of a large low pressure system and it still has a large circulation.  Winds to tropical storm force extend out about 120 miles (195 km) from the center on the eastern side of Lidia.

Tropical Storm Lidia was in an environment that was marginally favorable for intensification on Wednesday.  Lidia was moving over water where the Sea Surface Temperature was near 30°C.  An upper level ridge to the east of Lidia was producing westerly winds which were causing moderate vertical wind shear, especially over the northern half of the circulation.  The environment around Tropical Storm Lidia is forecast to become a little more favorable for intensification on Thursday.  The upper level winds are forecast to become weaker, which would reduce the wind shear.  Lidia will still be moving over very warm water and it should intensify on Thursday.  The rate of intensification could increase as the core of the tropical storm becomes more organized.  There is a chance that Lidia could strengthen into a hurricane which is why there is a Hurricane Watch for part of Baja California.

Lidia is moving around the western end of a subtropical ridge, which is steering the tropical storm toward the north-northwest.  A general north-northwesterly motion is expected to continue for another day or two.  On its anticipated track the center of Tropical Storm Lidia could reach the southern tip of Baja California by Thursday evening.  In addition to gusty winds Tropical Storm Lidia will produce very heavy rain.  Heavy rain falling on the steep terrain of Baja California creates the risk of flash floods.

Eugene Becomes a Hurricane Southwest of Baja California

Tropical Storm Eugene strengthened rapidly into a hurricane on Saturday as it moved southwest of Baja California.  At 11:00 p.m. EDT on Saturday the center of Hurricane Eugene was located at latitude 14.4°N and longitude 113.5°W which put it about 630 miles (1020 km) south-southwest of the southern tip of Baja California.  Eugene was moving toward the northwest at 8 m.p.h. (13 km/h).  The maximum sustained wind speed was 80 m.p.h. (130 km/h) and there were wind gusts to 95 m.p.h. (155 km/h).  The minimum surface pressure was 990 mb.

A primary raindband wrapped around the center of Hurricane Eugene on Saturday and an eye formed at the center of circulation.  The eye had a diameter of 30 miles (50 km).  Additional bands of showers and thunderstorms were revolving around the core of the circulation.  Thunderstorms were generating well developed upper level divergence which was pumping mass away in all directions.  The circulation of Hurricane Eugene was symmetrical and well organized.

Hurricane Eugene was moving over water where the Sea Surface Temperature (SST) was near 29°C.  Eugene was underneath the western end of an upper level ridge.  The ridge was producing southerly winds which were blowing toward the top of the hurricane, but the vertical wind shear was not very strong.  Eugene is likely to intensify on Sunday.  It will gradually move over cooler SSTs and Hurricane Eugene will move over water where the water is cooler than 26°C on Monday.  When Eugene reaches the cooler SSTs, it will begin a steady weakening trend.

Hurricane Eugene is moving around the western end of a subtropical ridge which is steering it toward the northwest.  Eugene is expected to continue to move toward the northwest during the next several days.  On its anticipated track Hurricane Eugene will move parallel to the west coast of Baja California.