Tag Archives: 20E

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.

Tropical Storm Rosa Develops Southwest of Mexico

Tropical Storm Rosa developed southwest of Mexico on Tuesday morning.  At 11:00 a.m. EDT on Tuesday the center of Tropical Storm Rosa was located at latitude 14.7°N and longitude 108.0°W which put it about 385 miles (620 km) southwest of Manzanillo, Mexico.  Rosa was moving toward the west-northwest at 9 m.p.h. (15 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.

A distinct center of circulation consolidated in an area of thunderstorms southwest of Mexico on Tuesday morning and the National Hurricane Center designated the system as Tropical Storm Rosa.  An inner rainband wrapped tightly around the center.  Several other bands of showers and thunderstorms were revolving around the core of Tropical Storm Rosa.  The circulation was symmetrical and rainbands were occurring in all parts of the tropical storm.  Storms near the core began to generate upper level divergence which was pumping mass away from Rosa.

Tropical Storm Rosa will move through an environment favorable for intensification during the next several days.  Rosa 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 be little vertical wind shear.  Tropical Storm Rosa could intensify into a hurricane by later on Wednesday.

Tropical Storm Rosa will move southwest of a middle level ridge over northern Mexico.  The ridge will steer Rosa in a general west-northwesterly direction during the next several days.  On its anticipated track Tropical Storm Rosa will move southwest of Baja California later this week.

Tropical Storm Selma Makes Landfall in El Salvador

Tropical Storm Selma made landfall in El Salvador on Saturday morning.  Selma weakened to a tropical depression after it moved inland.  At 11:00 a.m. EDT on Saturday the center of Tropical Depression Selma was located at latitude 13.7°N and longitude 88.5°W which put it about 45 miles (75 km) east of San Salvador, El Salvador.  Selma was moving toward the northeast at 8 m.p.h. (13 km/h).  The maximum sustained wind speed was 35 m.p.h. (55 km/h) and there were wind gusts to 45 m.p.h. (75 km/h).  The minimum surface pressure was 1006 mb.

The coastal warnings and watches for El Salvador and Honduras have been discontinued.

Tropical Depression Selma will continue to weaken as it moves farther inland.  The higher mountains will disrupt the circulation in the lower levels, but the circulation in the middle and upper levels could persist longer.  Tropical Depression Selma will drop locally heavy rain over El Salvador, western Honduras and eastern Guatemala.  The heavy rain could produce flash floods and mudslides.

Tropical Storm Selma Forms South of El Salvador

Tropical Storm Selma formed south of El Salvador on Friday morning.  At 11:00 a.m. EDT on Friday the center of Tropical Storm Selma was located at latitude 11.1°N and longitude 89.5°W which put it about 180 miles (290 km) south of San Salvador, El Salvador.  Selma was moving toward the northwest 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 1005 mb.

A Tropical Storm Warning has been issued for the entire coast of El Salvador.  A Tropical Storm Watch has been issued for the entire Pacific Coast of Guatemala.

A distinct low level center of circulation formed in a larger area of thunderstorms south of El Salvador on Friday morning and the National Hurricane Center designated the system as Tropical Storm Selma.  The circulation of Tropical Storm Selma is very asymmetrical.  Most of the showers and thunderstorms are located in the western half of the circulation.  There are bands of showers in the eastern half of the circulation.  An upper level ridge centered over the Yucatan Peninsula is producing easterly winds which are blowing over the top of the circulation.  Those winds are causing moderate vertical wind shear which is the primary reason for the asymmetrical structure of the circulation.  Selma is a small tropical storm.  Winds to tropical storm force only extend out about 45 miles (75 km) from the center of circulation.

Tropical Storm Selma will be moving through an environment that is neutral for intensification.  Selma will move over water where the Sea Surface Temperature is near 29°C.  The upper level ridge will continue to cause moderate vertical wind shear.  The shear will inhibit further intensification.  If the upper level winds weaken, then some intensification may be possible.  However, if the upper level winds get stronger, then Selma could weaken to a tropical depression.

A large counterclockwise circulation centered over Nicaragua and Honduras is steering Tropical Storm Selma slowly toward the northwest and the general motion is expected to continue on Friday.  The upper level ridge over the Yucatan Peninsula will weaken on Saturday and that will allow Tropical Storm Selma to move more toward the north.  On its anticipated track Tropical Storm Selma will make landfall on the coast of El Salvador or Guatemala on Saturday.

Tropical Storm Selma will bring some gusty winds to the coast.  However, locally heavy rain and flash floods will be the primary risks associated with Tropical Storm Selma when it makes landfall.

Seymour Strengthens Into a Cat. 4 Hurricane

Hurricane Seymour strengthened into a small but very powerful Category 4 hurricane on the Saffir-Simpson Scale on Tuesday.  At 11:00 p.m. EDT on Tuesday the center of Hurricane Seymour was located at latitude 16.1°N and longitude 117.7°W which put it about 690 miles (1110 km) southwest of the southern tip of Baja California.   Seymour was moving toward the west-northwest at 15 m.p.h.  The maximum sustained wind speed was 150 m.p.h. (240 km/h) and there were wind gusts to 175 m.p.h. (280 km/h).  The minimum surface pressure was 943 mb.

The circulation of Hurricane Seymour is very small, but it is very well organized.  There is a circular eye with a diameter of 10 miles (12 km) which is surrounded by a ring of strong thunderstorms.  Winds to hurricane force only extend out about 18 miles (29 km) from the center of circulation.  Winds to tropical storm force extend out about 80 miles (130 km) from the center.  The Hurricane Intensity Index (HII) is 31.6, but the Hurricane Size Index (HSI) is only 7.1.  The Hurricane Wind Intensity Size Index is 38.7.  Hurricane Seymour is not as strong as Hurricane Patricia was in 2015 and Seymour is smaller than Patricia was.  When Hurricane Patricia had maximum sustained winds of 200 m.p.h. (320 km) its HSI ranged between 11.3 and 13.8.

Hurricane Seymour will remain in a very favorable environment for another 6 to 12 hours.  It will move over water where the Sea Surface Temperature (SST) is near 28°C.  The upper level winds will be light and there will be little vertical wind shear.  Later on Wednesday the upper level winds will increase and Hurricane Seymour will begin to move over cooler SSTs.  The increasingly unfavorable environment will cause Seymour to weaken.  Because of the small size of Seymour’s circulation, wind shear could cause the hurricane to weaken quickly.

Hurricane Seymour is moving around the western end of a ridge that is steering the hurricane toward the west-northwest.  When Seymour reaches the western end of the ridge, the hurricane will begin to move more toward the north.  On its anticipated track Hurricane Seymour will weaken well to the west of Baja California.  An upper level trough moving over the Northern Pacific Ocean could eventually transport some of the moisture from Hurricane Seymour over the western U.S.

Seymour Rapidly Intensifies into a Cat. 2 Hurricane

Tropical Storm Seymour rapidly intensified into a Category 2 hurricane on the Saffir-Simpson Scale on Monday as it moved farther away from Mexico.  At 11:00 p.m. EDT on Monday the center of Hurricane Seymour was located at latitude 15.5°N and longitude 112.6°W which put it about 540 miles (870 km) south-southwest of the southern tip of Baja California.  Seymour was moving toward the west at 16 m.p.h. (26 km/h).  The maximum sustained wind speed was 105 m.p.h. (165 km/h) and there wind gusts to 125 m.p.h. (200 km/h).  The minimum surface pressure was 976 mb.

Hurricane Seymour intensified very rapidly on Monday.  The maximum sustained wind speed increased from 50 m.p.h. (80 km/h) to 105 m.p.h. (165 km/h) in a 24 hour period.  The circulation contracted and the primary rainband wrapped tightly around a small eye.  Seymour is a very small hurricane and hurricane force winds only extend out about 12 miles (19 km) from the center of circulation.  Winds to tropical storm force only extend out about 70 miles (130 km) from the center.  Although Seymour is a small hurricane, the circulation is well organized.  The small eye is surrounded by an almost continuous ring of thunderstorms.  Several other spiral bands are rotating around the core of Hurricane Seymour.  Thunderstorms in the core are generating upper level divergence which is pumping out mass in all directions.

Hurricane Seymour will remain in a favorable environment on Tuesday.  It is moving over water where the Sea Surface Temperature is near 30°C.  The upper level winds are light and there is little vertical wind shear.  Hurricane Seymour is likely to intensify on Tuesday and it could become a major hurricane.  When Seymour moves farther to the west, it will be nearer to an upper level trough which will produce southwesterly winds over the hurricane.  Increased vertical wind shear will begin to weaken Hurricane Seymour.

A ridge over Mexico is steering Hurricane Seymour toward the west and that general motion will occur for another 24 to 36 hours.  Hurricane Seymour will approach the western end of the ridge on Wednesday, and the hurricane will turn more toward the north when that happens.  On its anticipated track this turn will occur well to the west of Baja California.

Tropical Storm Seymour Develops Quickly West of Mexico

Tropical Storm Seymour developed quickly west of Mexico on Sunday and it brought to an end a stretch of three quiet weeks over the Eastern North Pacific Ocean.  At 11:00 p.m. EDT on Sunday the center of Tropical Storm Seymour was located at latitude 14.4°N and longitude 107.1°W which put it about 370 miles (590 km) south-southwest of Manzanillo, Mexico.  Seymour was moving toward the west-northwest at 15 m.p.h. (24 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.

The circulation in a cluster of thunderstorms organized quickly on Sunday afternoon.  A primary rainband around the northern and western sides of the circulation wrapped almost entirely around the center and an eye appeared to be forming on microwave satellite images.  Additional bands of thunderstorms were developing.  Thunderstorms in the core of Seymour were beginning to generate upper level divergence.

Tropical Storm Seymour will be moving through a very favorable environment.  It is moving over water where the Sea Surface Temperature is near 31°C.  The upper level winds are relatively weak and there is little vertical wind shear.  Tropical Storm Seymour will continue to intensify and it could intensify rapidly.  Seymour will become a hurricane and it could become a major hurricane.

A ridge over Mexico is steering Tropical Storm Seymour toward the west-northwest and that general motion is expected to continue for several more days.  When Seymour reaches the western end of the ridge, it will turn toward the north.  On its anticipated track Tropical Storm Seymour will make the northward turn well to the southwest of Baja California.

Patricia Is Strongest East Pacific Hurricane on Record

Hurricane Patricia continued to intensify rapidly during the overnight hours and it is now the strongest hurricane on record for the Eastern North Pacific.  At 11:00 a.m. EDT on Friday the center of Hurricane Patricia was located at latitude 17.6°N and longitude 105.5°W which put it about 125 miles (200 km) southwest of Manzanillo, Mexico.  Patricia was moving toward the north at 10 m.p.h. (16 km/h).  The maximum sustained wind speed was 200 m.p.h. (320 km) and there were wind gusts to 245 m.p.h. (400 km/h).  The minimum surface pressure was 880 mb.

A Hurricane Warning is in effect for the portion of the coast between Sas Blas and Punta San Telmo, Mexico.  A Tropical Storm Warning and a Hurricane Watch is in effect for the portion of the coast from Punta San Telmo to Lazaro Cardenas, Mexico.

Hurricane Patricia has broken a number of records.  The maximum sustained wind speed increased from 85 m.p.h. to 200 m.p.h. between 5:00 a.m. EDT on Thursday and 5:00 a.m. EDT on Friday.  The rate of increase of 115 m.p.h. in 24 hours is the fastest rate of intensification observed in the Eastern Pacific. It exceeds the 100 m.p.h. in 24 hours that occurred in Hurricane Linda in 1997.  Interestingly, 1997 was also an El Nino year.  The minimum surface pressure of 880 mb is the lowest ever recorded in the National Hurricane Center’s Area of Responsibility which includes the Atlantic and Eastern North Pacific Oceans.  It is lower than the 882 recorded when Hurricane Wilma was over the Caribbean Sea in 2005.

Hurricane Patricia is an extremely dangerous hurricane.  It has a Hurricane Intensity Index (HII) of 50.0, a Hurricane Size Index (HSI) of 11.3 and a Hurricane Wind Intensity Size Index (HWISI) of 61.3.  Those indices mean that Patricia will be capable of causing catastrophic regional damage when it reaches the west coast of Mexico north of Manzanillo later on Friday.  Hurricane Patricia will be capable of causing catastrophic wind damage, generating a potentially destructive storm surge near the coast and producing heavy rain and flooding as it moves inland.