Tag Archives: southwestern U.S.

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 Depression 16E Could Bring Heavy Rain to Southwest U.S.

A center of circulation organized within a cluster of thunderstorms west of Baja California on Sunday and the system was designated Tropical Depression Sixteen-E.  At 5:00 p.m. EDT on Sunday the center of Tropical Depression Sixteen-E (TD16E) was located at latitude 25.0°N and longitude 113.7°W which put it about 90 miles (145 km) west of Cabo San Lazaro, Mexico.  TD16E was moving toward the north-northwest at 14 m.p.h. (22 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. (70 km/h).  The minimum surface pressure was 1003 mb.

Tropical Depression 16E has only a few hours before it will move over the central part of Baja California.  Although it is over water where the Sea Surface Temperature is near 27°C little, if any, intensification is expected.  When TD16E crosses Baja California, the terrain and increased vertical wind shear are likely to blow the upper portion of the circulation northward faster than the lower portion of the circulation.  The high clouds could reach parts of the southwestern U.S. within 24 hours.  Moving over mountains will disrupt the lower part of the circulation, but the rotation in the middle levels could persist for several days as it moves northward.

An upper level ridge centered over Texas and an upper level low west of Baja California are combining to steer TD16E northward and that general motion should continue for the next several days.  On its anticipated track TD16E could reach the coast of Baja California near Punta Abreojos in about 12 hours.  It could then move across Baja and the Gulf of California and make a second landfall on the coast west of Hermosillo on Monday morning.  TD16E or its remnants could be approaching southern Arizona later on Monday.  Convection and a flow of moisture associated with TD16E could produce locally heavy rainfall when it is forced to rise of mountains.  It could cause flooding in parts of Baja California, northwestern Mexico and the southwestern U.S.

Tropical Storm Kevin Forms Southwest of Baja California

Vertical wind shear decreased enough on Thursday to allow more thunderstorms to develop near the center of Tropical Depression 14E and the National Hurricane Center upgraded it to Tropical Storm Kevin.  At 11:00 a.m. EDT on Thursday the center of Tropical Storm Kevin was located at latitude 17.9°N and longitude 115.6°W which put it about 505 miles (815 km) southwest of the southern tip of Baja California.  Kevin was moving toward the north at 6 m.p.h. (9 km/h).  The maximum sustained wind speed was 50 m.p.h. (80 km/h) and there were wind gusts to 60 m.p.h. (95 km/h).  The minimum surface pressure was 1000 mb.

Tropical Storm Kevin is a small tropical cyclone.  Winds to tropical storm force only extend out about 70 miles (115 km) from the center of circulation.  There is one short spiral band wrapping around the northwest side of the center and another short band wrapping around the southwest side of the center.  There are not many thunderstorms in the eastern half of the circulation.  Kevin is over water where the Sea Surface Temperature (SST) is near 29°C.  However, a large, high amplitude upper level trough along the west coast of the U.S. is generating moderate southwesterly winds over the top of Kevin.  The vertical wind shear inhibited the development of Kevin, but the shear seems to have lessened today and the circulation in the tropical storm has consolidated around the center.  Thunderstorms near the center of Kevin are generating upper level divergence over a small area.

As Kevin moves farther north it will move over cooler SSTs.   When it gets north of latitude 22°N, Kevin will move over SSTs cooler than 26°C.  If the vertical wind shear remains moderate, Kevin could intensify further during the next 24 to 48 hours.  After about two days, the tropical storm will move over cooler SSTs and into an area with more vertical wind shear.  At that point Kevin is likely to start to spin down.

A ridge over Mexico is steering Kevin toward the north and that general motion is expected to continue for another day or two.  When Kevin moves over cooler SSTs, the thunderstorms will not be as tall and it will be steered by the winds lower in the atmosphere.  Those winds could push Kevin more toward the west during the weekend.

Hurricane Odile Bringing Winds/Rain to Baja California

Hurricane Odile is bringing strong winds and heavy rain to portions of Baja California as it moves up the peninsula.  At 11:00 a.m. EDT on Monday the center of Hurricane Odile was located at latitude 24.7°N and longitude 111.3°W which put it about 90 miles south of Loreto, Mexico.  Odile was moving toward the northwest at 14 m.p.h.  The maximum sustained wind speed was 100 m.p.h. and the minimum surface pressure was 955 mb.  When the center of Odile moved over the southern tip of Baja California during the night, it tied Hurricane Olivia (1967) as the strongest hurricane to make landfall in Baja California Sur in the satellite era.

A Hurricane Warning is in effect for the portion of the coast from Punta Abreojos southward to the southern tip of Baja California and then northward to Santa Rosalia.  A Hurriane Watch is in effect from Punta Abreojos to Punta Eugenia.  Tropical Storm Warnings are in effect from Santa Rosalia northward to Bahia de Los Angeles, from Punta Eugenia northward to San Jose de Las Palomas, and from Altata to Bahia Kino.  Tropical Storm Watches are in effect from San Jose de Las Palomas northward to Cabo San Quintin, from Bahia de Los Angeles to San Felipe and from Bahia Kino to Puerto Libertad.

Odile is expected to continue moving over Baja California in the short term.  Interaction with the mountains in Baja California sometimes causes the upper parts of the circulations around tropical cyclones to be decoupled from the lower level rotation.  This makes track forecasts challenging because the upper and lower portions of the storms can go in different directions.  Odile or at least the upper and middle portions of the circulation could eventually turn more toward the north or north-northeast and some portion of Odile could spend a period of time over the Gulf of California.  It is possible that the low level circulation gets left behind and meanders along the west coast of Baja, California.

The mountains in Baja California should continue to weaken the circulation as long as the center remains over land.  If the circulation maintains a coherent vertical structure and moves over the Gulf of California, some re-intensification is possible.  The Sea Surface Temperatures in the Gulf of California are very warm.  Increased wind shear and land interaction will ultimately weaken Odile as it moves farther north.

The more northward track of Odile increases the potential for it to pull moist air into portions of the southwestern U.S. and some areas could see significant rainfall later this week.

 

Odile Becomes a Hurricane

Tropical Storm Odile has intensified into a hurricane as it moves slowly toward the northwest off the west coast of Mexico.  At 11:00 a.m. EDT on Saturday the center of Hurricane Odile was located at latitude 16.6°N and longitude 106.0°W which put it about 200 miles south-southwest of Manzanillo, Mexico and about 505 miles south of the southern tip of Baja California.  Odile was moving toward the northwest at 6 m.p.h.  The maximum sustained wind speed was 80 m.p.h. and the minimum surface pressure was 980 mb.

The upper level high over northern Mexico that was generating northeasterly winds over Odile has shifted eastward.  As a result, the upper level wind shear has decreased and Odile is intensifying.  Odile will be over warm Sea Surface Temperatures (SSTs) during the next several days and it should continue to intensify.  A period of more rapid intensification is possible.

The winds in the middle level steering Odile should keep pushing it in a northwesterly direction.  Much of the computer guidance suggests that Odile will pass south of the tip of Baja California and then move west of Baja.  It could take a path similar to the track taken by Hurricane Norbert.

The government of Mexico issued a new Tropical Storm Watch for a portion of the coast of Baja California that extends from La Paz to Santa Fe.  A Tropical Storm Watch remains in effect for the portion of the coast from Manzanillo to Cabo Corrientes.

If Odile moves west of Baja California, southerly winds in the eastern half of the circulation could transport significant water vapor over the southwestern U.S.  In addition, a strong flow of moist air is occurring over northeastern Mexico associated with the northern portion of a tropical wave moving inland in that area.  The combination of these two flows of moist air could create a potential for locally heavy rains over parts of the southwestern U.S. next week.