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Hurricane Willa Strengthens to Cat. 5, Poses Imminent Threat to Mexico

Hurricane Willa strengthened Monday morning to Category 5 on the Saffir-Simpson Scale and Willa poses an imminent threat to Mexico.  At 11:00 a.m. EDT on Monday the center of Hurricane Willa was located at latitude 19.1°N and longitude 107.2°W which put it about 135 miles (215 km) southwest of Cabo Corrientes.  Willa was moving toward the north at 7 m.p.h. (11 km/h).  The maximum sustained wind speed was 160 m.p.h. (260 km/h) and there were wind gusts to 190 m.p.h. (305 km/h).  The minimum surface pressure was 925 mb.

A Hurricane Warning was in effect for the portion of the coast from San Blas to Mazatlan, Mexico.  Tropical Storm Warnings were in effect for the portion of the coast from Playa Perula to San Blas and from Mazatlan to Bahia Tempehuaya, Mexico.

Hurricane Willa strengthened from a tropical storm to a Category 5 hurricane in 36 hours.  Willa is a small, very well organized hurricane.  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.  Several bands of showers and thunderstorms are revolving around the core of Hurricane Willa.  Storms near the core are generating strong upper level divergence which is pumping mass away from the hurricane.

Hurricane Willa is a small hurricane.  Winds to hurricane force extend out about 30 miles ( 50 km) from the center of Willa.  Winds to tropical storm force extend out about 100 miles (160 km) from the center of circulation.  The Hurricane Intensity Index (HII) for Hurricane Willa is 35.0.  The Hurricane Size Index (HSI) is 9.7 and the Hurricane Wind Intensity Size Index (HWISI) is 44.7.  The core of Hurricane Willa is capable of causing catastrophic damage.

Hurricane Willa will remain in an environment capable of supporting strong hurricanes for about another 24 hours.  Willa will move over water where the Sea Surface Temperature is near 29°C.  It will move through an environment where the upper level winds are weak and there will be little vertical wind shear.  If an outer rainband wraps around the existing eye and eyewall, then an eyewall replacement cycle could cause Hurricane Willa to weaken.  An upper level trough near the West Coast of the U.S. will produce southwesterly winds which will blow toward the top of Hurricane Willa on Tuesday.  Those winds will cause vertical wind shear and the shear will start to weaken Willa.  Since Willa is a small hurricane, it will weaken faster than a larger hurricane would weaken.

Hurricane Willa will move around the western end of a ridge of high pressure over Mexico.  The ridge will steer Willa toward the north for another 12 hours or so.  Then the upper level trough will turn Hurricane Willa toward the northeast.  On its anticipated track Hurricane Willa will move over the Islas Marias on Tuesday morning.  Willa will reach the coast of Mexico between San Blas and Mazatlan on Tuesday afternoon or evening.

Hurricane Willa could still be a major hurricane when it reaches the coast of Mexico.   Willa will be capable of causing major damage.  The core of Hurricane Willa will bring damaging winds.  It will also produce a storm surge of 10 to 13 feet (3 to 4 meters) near where core of Willa makes landfall.  Hurricane Willa will drop heavy rain over Nayarit, Sinaloa and Durango.  The heavy rain could cause flash floods in some locations.

Elsewhere over the Eastern North Pacific Ocean, upper level divergence from Hurricane Willa appeared to be causing wind shear which was weakening Tropical Storm Vicente.  At 11:00 a.m. EDT on Monday the center of Tropical Storm Vicente was located at latitude 14.9°N and longitude 100.8°W which put it about 365 miles (590 km) southeast of Manzanillo, Mexico.  Vicente was moving toward the west-northwest 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 1004 mb.

Willa Rapidly Intensifies Into a Major Hurricane, Warnings Issued for Mexico

Hurricane Willa intensified rapidly into a major hurricane on Sunday and Warnings were issued for Mexico.  At 11: 00 p.m. EDT on Sunday the center of Hurricane Willa was located at latitude 17.7°N and longitude 107.2°W which put it about 210 miles (340 km) south-southwest of Cabo Corrientes, Mexico.  Willa was moving toward the north-northwest at 7 m.p.h. (11 km/h).  The maximum sustained wind speed was 145 m.p.h. (230 km/h) and there were wind gusts to 170 m.p.h. (275 km/h).  The minimum surface pressure was 941 mb.  Hurricane Willa was a Category 4 hurricane on the Saffir-Simpson Scale.

A Hurricane Warning was in effect for the portion of the coast from San Blas to Mazatlan, Mexico.  A Tropical Storm Warning was in effect for the portion of the coast from Playa Perula to San Blas.  A Tropical Storm Warning was also in effect for the portion of the coast from Mazatlan to Bahia Tempehuaya.

Hurricane Willa intensified from a tropical storm to a Category 4 hurricane in 24 hours.  A small circular eye formed at the center of Hurricane Willa.  The eye was surround by a ring of strong thunderstorms and the strongest winds were occurring in that ring of storms.  Several bands of showers and thunderstorms were revolving around the core of Hurricane Willa.  Storms near the core were generating strong upper level divergence which was pumping large quantities of mass away from the hurricane.  The strong divergence allowed the surface pressure to decrease quickly and that caused the wind speeds to increase rapidly.

Willa is a small hurricane.  Winds to hurricane force only extend out about 25 miles (40 km) from the center of Hurricane Willa.  Winds to tropical storm force only extend out about 90 miles (145 km) from the center of circulation.  The Hurricane Intensity Index (HII) for Hurricane Willa is 29.9.  The Hurricane Size Index (HSI) is 8.2 and the Hurricane Wind Intensity Size Index (HWISI) is 38.1.

Hurricane Willa will move through an environment favorable for intensification during the next 12 to 24 hours.  Willa will move over water where the Sea Surface Temperature is near 29°C.  It will move through a region where the upper level winds are weak and there will not be much vertical wind shear.  Hurricane Willa could strengthen to a Category 5 hurricane on the Saffir-Simpson Scale during the next 12 hours.  An upper level trough near the west coast of the U.S. will produce southwesterly winds which will start to affect Hurricane Willa in about 24 hours.  Those winds will cause vertical wind shear, which will cause Willa to start to weaken.

Hurricane Willa will move around the western end of a ridge of high pressure over Mexico.  The ridge will steer Willa toward the north on Monday.  The upper level trough near the west coast of the U.S. will turn Hurricane Willa toward the northeast on Tuesday.  On its anticipated track Hurricane Willa could make landfall on the coast of Mexico on Tuesday night.  Willa could be a major hurricane when it approaches the coast.  It will be capable of causing major wind damage and a significant storm surge along the coast.  Willa will also drop locally heavy rain and it could flash floods when it moves inland over Mexico.

Elsewhere over the Eastern North Pacific Ocean Tropical Storm Vicente was moving near the southeastern periphery of Hurricane Willa.  At 11:00 p.m. EDT on Sunday the center of Tropical Storm Vicente was located at latitude 13.9°N and longitude 98.7°W which put it about 220 miles (355 km) south-southeast of Acapulco, Mexico.  Vicente was moving toward the west at 10 m.p.h. (16 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 1005 mb.

Tropical Storm Willa Strengthens Quickly Southwest of Mexico

Only one day after the formation of Tropical Storm Vicente, Tropical Storm Willa strengthened quickly southwest of Mexico.  At 5:00 p.m. EDT on Saturday the center of Tropical Storm Willa was located at latitude 15.2°N and longitude 105.8°W which put it about 280 miles (450 km) south-southwest of Manzanillo, Mexico.  Will was moving toward the west-northwest at 6 m.p.h. (10 km/h).  The maximum sustained wind speed was 60 m.p.h. (95 km/h) and there were wind gusts to 75 m.p.h. (120 km/h).  The minimum surface pressure was 999 mb.

Several bands of showers and thunderstorms wrapped tightly around a distinct low level center of circulation on Saturday and the National Hurricane Center designated the system as Tropical Storm Willa.  Willa continued to organize quickly on Saturday afternoon.  Bands of showers and thunderstorms formed and began to revolve around the core of Tropical Storm Willa.  Storms near the core started to generate upper level divergence which pumped mass away from the tropical storm.  The circulation around Tropical Storm Willa was still compact.  Winds to tropical storm force only extended out about 35 miles (55 km) from the center of circulation.

Tropical Storm Willa will move through an environment favorable for intensification.  Willa will move over water where the Sea Surface Temperature is near 29°C.  It will move through an area where the upper level winds are weak and there will be little vertical wind shear.  Willa is likely to intensify into a hurricane during the next 24 hours.  It could intensify rapidly and there is a chance Tropical Storm Will could strengthen into a major hurricane during the next two or three days.

Tropical Storm Willa will move around the western end of a ridge of high pressure over Mexico during the next two or three days.  The ridge will steer Willa toward the northwest during the next 24 to 48 hours.  An upper level trough west of California will turn Willa toward the northeast in about 48 hours.  On its anticipated track Willa could approach the coast of Mexico in about fours.  Willa could be a hurricane when it nears the coast.

Elsewhere over the Eastern North Pacific Ocean, Tropical Storm Vicente also strengthened on Saturday.  At 5:00 p.m. EDT on Saturday the center of Tropical Storm Vicente was located at latitude 14.6°N and longitude 94.3°W which put it about 120 miles (200 km) south-southeast of Salina Cruz, Mexico.  Vicente was moving toward the west at 9 m.p.h. (15 km/h).  The maximum sustained wind speed was 50 m.p.h. (80 km/h) and there were wind gusts to 65 m.p.h. (105 km/h).  The minimum surface pressure was 1002 mb.

Small Tropical Storm Vicente Forms Southwest of Guatemala

Small Tropical Storm Vicente formed southwest of Guatemala on Friday.  At 5:00 p.m. EDT on Friday the center of Tropical Storm Vicente was located at latitude 13.3°N and longitude 92.2°W which put it about 110 miles (180 km) south of Tapachula, Mexico.  Vicente was moving toward the northwest at 2 m.p.h. (3 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 1005 mb.

Tropical Storm Vicente formed out of a tropical wave that almost produced a tropical depression over the western Caribbean Sea earlier this week .  An area of low pressure developed within the tropical wave, but the low moved over Honduras before it could organize enough to be designated as a tropical depression.  The low continued to organize once it moved over the Eastern North Pacific Ocean southwest of Guatemala.  A distinct low level center of circulation was evident on visible satellite imagery on Friday and the National Hurricane Center designated the system at Tropical Storm Vicente.

The circulation around Tropical Storm Vicente is very small.  Winds to tropical storm force only extend out about 35 miles (55 km) from the center of circulation.  Vicente does have a well developed center and a ring of thunderstorms surrounds the center of circulation.  Several short bands of showers and thunderstorms were revolving around the core of Tropical Storm Vicente.  Storms around the core were generating upper level divergence which was pumping mass away from the tropical storm.

Tropical Storm Vicente will move through an environment mostly favorable for intensification.  Vicente will move over water where the Sea Surface Temperature is near 29°C.  It will move through an area where the upper level winds are weak and there will be little vertical wind shear.  Tropical Storm Vicente is likely to strengthen during the next 24 to 36 hours.  Northerly winds blowing across the Isthmus of Tehuantepec will transport drier air over the Gulf of Tehuantepec.  If the drier air enters the circulation of Vicente, then the tropical storm could weaken.  Since the circulation around Tropical Storm Vicente is so small, the tropical storm could intensify or weaken very rapidly if the environmental conditions change.

Tropical Storm Vicente will move around a ridge of high pressure over the Gulf of Mexico and Mexico.  The ridge will steer Vicente in a general westerly direction during the weekend.  On its anticipated track Tropical Storm Vicente will stay south of Mexico during the next 24 to 48 hours.  Vicente could move more toward the northwest early next week when it moves around the western end of the ridge of high pressure.