Tropical Cyclone Raquel Reorganizing Near Solomon Islands

Strong upper level winds blew away the upper potion of Tropical Cyclone Raquel on Wednesday.  However, the upper level winds lessened on Thursday and thunderstorms began to reform on the western side of the circulation.  At 5:00 p.m. EDT on Thursday the center of Tropical Cyclone Raquel was located at latitude 6.4°S and longitude 160.5°E which put it about 220 miles (360 km) north of Honiara in the Solomon Islands.  Raquel was moving toward the south-southeast at 3 m.p.h. (5 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 994 mb.

Tropical Cyclone Raquel is over water where the Sea Surface Temperatures are very warm.  However, an upper level ridge east of Raquel generated strong winds over the top of the tropical cyclone on Wednesday and blew away the upper parts of the circulation.  The upper level winds weakened on Thursday and new thunderstorms began to develop west of the center of circulation.  Upper level divergence is also occurring in the western half of the circulation and Raquel looks like a tropical cyclone again.  The upper level winds are still strong enough to inhibit intensification, but Raquel could strengthen further in the short term.

When the top parts of the circulation were blown away on Wednesday, the lower level circulation was steered by winds in the lower troposphere and it moved toward the northeast.  As the thunderstorms redevelop, the height of the circulation is increasing and Raquel is more likely to be steered by winds in the middle troposphere.  Those winds are expected to steer Raquel back toward the southwest.  On its anticipated track Raquel could again approach Santa Isabel Island on Friday.  It could bring winds and locally heavy rain to portions of the Central Solomon Islands.

Tropical Storm Chan-hom Forms East of Guam

A center of circulation developed in an area of thunderstorms on the opposite side of the Equator from Tropical Cyclone Raquel and it was designated as Tropical Storm Chan-hom on Tuesday.  At 11:00 p.m. EDT on Tuesday the center of Tropical Storm Chan-hom was located at latitude 11.0°N and longitude 156.5°E which put it about 250 miles (400 km) north-northeast of Oroluk atoll and about 800 miles (1290 km) east of Guam.  Chan-hom was moving toward the west at 22 m.p.h. (35 km/h).  The maximum sustained wind speed was 45 m.p.h. (70 km/h) and there were wind gusts to 60 m.p.h. (95 km/h).  The minimum surface pressure was 993 mb.

Tropical Storm Chan-hom formed over water where the Sea Surface Temperatures (SSTs) are around 29°C to 30°C and there is plenty of energy in the upper ocean to support intensification.  An upper level ridge located north of the tropical storm is generating easterly winds over the top of the circulation.  The easterly winds are generating moderate amounts of vertical wind shear and many of the stronger thunderstorms are occurring in the western half of the circulation.  Those thunderstorms are producing strong rising motion and upper level divergence is well developed on the western side of Chan-hom.  However the upper level easterly winds are interfering with upper level divergence on the eastern side of the tropical storm.  As a result, a modest rate of intensification is expected in the short term.  If the upper level winds were to lessen, then a more rapid rate of intensification would be possible.

The upper level ridge is expected to steer Chan-hom toward the west during the next several days.  On its anticipated track Chan-hom could approach Guam in about three days.  It could be a typhoon by that time.  However, there is some divergence in the track guidance from numerical models at the end of this week and that is producing uncertainty about the future track of Chan during that time period.

Tropical Cyclone Raquel Forms Near the Solomon Islands

A distinct low level center of circulation was detected inside a large area of thunderstorms north of the Solomon Islands and the system was designated as Tropical Cyclone Raquel (25P).  At 11:00 p.m. EDT on Tuesday the center of Tropical Cyclone Raquel was located at latitude 6.5°S and longitude 158.9°E which put it about 210 miles (335 km) north of Honiara in the Solomon Islands.  Raquel was moving toward the southwest at 11 m.p.h. (18 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 989 mb.

Raquel is over water where the Sea Surface Temperature is quite warm and there is plenty of energy in the upper ocean to support intensification.  However, and upper level ridge east of Raquel is northeasterly winds over the top of the circulation and it is creating moderate amounts of vertical wind shear.  The wind shear is causing many of the stronger thunderstorms to occur on the western side of the circulation.  The wind shear may be tilting the vertical structure of the circulation toward the southwest and it is limiting the potential for intensification.

As Raquel moves around the western end of the upper level ridge, it is expected to be steered toward the south on Wednesday.  On its anticipated track Raquel is expected to move across Santa Isabel on Wednesday.  It could be near Guadacanal in 36 to 48 hours.  Raquel is likely to bring some wind and locally heavy rain to parts of the central Solomon Islands during the next two days.

Tropical Storm Kujira Makes Landfall on Hainan Island

Tropical Storm Kujira made landfall on the east coast of Hainan Island on Monday.  At 11:00 p.m. EDT on Monday the center of Tropical Storm Kujira was located at latitude 19.9°N and longitude 109.1°E which put it about 100 miles (160 km) south of Beihai, China.  Kujira was moving toward the northwest 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 992 mb.

Passing across Hainan Island weakened Tropical Storm Kujira on Monday.  In addition, an upper level ridge over southern Asia continues to generate vertical wind shear over the tropical storm.  However, it will move over warm water when the center moves northwest of Hainan Island.  So, Kujira could maintain tropical storm intensity until it makes another landfall in China in about 18 to 24 hours.  The primary risk will be locally heavy rainfall.

Tropical Storm Kujira Nearing Hainan Island

Tropical Storm Kujira moved slowly northward on Sunday.  At 11:00 p.m. EDT on Sunday night the center of Tropical Storm Kujira was located at latitude 18.0°N and longitude 111.2°E which put it about 150 miles (240 km) south-southeast of Xuwen, China.  Kujira was moving toward the north-northwest at 7 m.p.h. (11 km/h).  The maximum sustained wind speed was 45 m.p.h. (70 km/h) and there were wind gusts to 65 m.p.h. (105 km/h).  The minimum surface pressure was 994 mb.

Although Kujira is moving over water where the Sea Surface Temperature is near 30°C, vertical wind shear is inhibiting intensification.  An upper level ridge over southern Asia is producing northeasterly winds over the top of Kujira.  As a result of the vertical shear, most of the stronger thunderstorms are occurring southwest of the center of circulation.  As Kujira moves farther north, some of the circulation will move over Hainan Island, which will further limit the potential for intensification.

Kujira is moving around the western end of a subtropical ridge which is steering the tropical storm toward the north.  The steering pattern is expected to remain in place for the early part of the week.  Kujira could be very close to the east coast of Hainan Island in about 12 hours.  It will move near or just east of Hainan and Kujira could make landfall in China in 24 to 36 hours.  Although it will bring some wind, the primary risk will be locally heavy rainfall.

Tropical Storm Kujira Forms South of Hainan Island

A surface circulation organized within a larger area of thunderstorms east of Vietnam on Saturday and the system was designated as Tropical Storm Kujira.  At 11:00 p.m. EDT on Saturday the center of Tropical Storm Kujira was located at latitude 15.7°N and longitude 111.4°E which put it about 210 miles (340 km) east of Da Nang, Vietnam.  Kujira was moving north-northwest at 3 m.p.h. (5 km/h).  The maximum sustained wind speed was 40 m.p.h. (65 km/h) and there were wind gusts to 60 m.p.h. (95 km/h).  The minimum surface pressure was 998 mb.

Tropical Storm Kujira is moving over water where the Sea Surface Temperature is near 30°C.  However an upper level ridge over southern Asia is generating northeasterly winds over the top of Kujira.  Those northeasterly winds are producing moderate vertical wind shear, which is causing most of the stronger thunderstorms to be located in the western half of the circulation.  Some spiral bands are beginning to form and a band is wrapping around the southern side of the center of circulation.  It appears that Kujira is becoming more well organized and intensification is likely, although the wind shear could slow that process.

Kujira is in an area where the steering currents are weak.  The tropical storm is near the western end of a subtropical ridge and the highest probability is that it will move north toward Hainan Island and southern China.  Some numerical models project a landfall on Hainan Island, but others have Kujira passing east of the island before making landfall on the coast of China.  In either scenario Kujira could approach Hainan Island in 24 to 36 hours.

Tropical Depression Bill Bringing Storms to Lower Ohio Valley

The circulation around Tropical Depression Bill brought strong storms to the Lower Ohio River Valley on Friday.  At 5:00 p.m. EDT on Friday the center of Tropical Depression Bill was located at latitude 37.1°N and longitude 90.1°W which put it about 30 miles (50 km) west of Cape Girardeau, Missouri.  Bill was moving toward the east-northeast at 15 m.p.h. (24 km/h).  The maximum sustained wind speed was 25 m.p.h., but there were higher gusts in thunderstorms.  The minimum surface pressure was 1004 mb.

The circulation around Tropical Depression Bill retained enough tropical characteristics on Friday to be considered a tropical cyclone.  There was still evidence of a warm core in the middle troposphere with a strong center of circulation at the surface and divergent outflow in the upper levels.  Spiral bands of showers and thunderstorms continued to rotate cyclonically around the center, and some thunderstorms approached severe criteria.  A stationary frontal boundary ran from New Jersey across Ohio to central Missouri.  However, the circulation around the tropical depression was south of the boundary and it was clearly a distinct area of low pressure.

Tropical Depression Bill is expected to continue its east-northeasterly motion during the weekend.  It will pass south of Ohio on Saturday and cross New Jersey on Sunday.  The tropical depression will continue to produce locally heavy rainfall and the potential for isolated severe thunderstorms.

Tropical Depression Bill Bringing Rain to Arkansas and Missouri

Tropical Depression Bill continued its slow movement over the South Central U.S. on Thursday and it brought rain to Arkansas and southern Missouri.  At 11:00 p.m. EDT on Thursday the center of Tropical Depression Bill was located at latitude 35.9°N and longitude 93.8°W which put it about 20 miles (30 km) east of Fayetteville, Arkansas.  Bill was moving toward the east-northeast at 10 m.p.h. (16 km/h).  The maximum sustained wind speed was 20 m.p.h. (30 km/h) and the minimum surface pressure was 1005 mb.

Even thought the center of Bill has been over land for more than 48 hours, it retains many of the characteristics of a tropical cyclone.  It has a well defined cyclonic circulation with a warm core in the middle troposphere and there is upper level divergence.  As a result, Bill is still officially classified as a tropical depression.

Bill is moving around the western end of a high pressure system centered over the Atlantic Ocean.  It should continue to move toward the east-northeast during the next several days.  On its anticipated track Bill will bring rain to northern Arkansas and southern Missouri on Friday.  It will move up the Ohio River Valley on Saturday and enhance the rainfall in those areas.  The circulation of the tropical depression could merge with a nearly stationary frontal boundary north of the Ohio River during the weekend.  Heavy rain falling on saturated ground could create the potential for flooding in some areas.

Tropical Depression Bill Crossing Red River Into Oklahoma

Tropical Depression Bill moved northward across north Texas on Wednesday and brought heavy rain to parts of Texas and Oklahoma.  At 11:00 p.m. EDT on Wednesday the center of Tropical Depression Bill was located at latitude 33.7°N and longitude 97.3°W which put it about 65 miles (105 km) north-northwest of Dallas, Texas.  Bill was moving toward the north at 10 m.p.h. (16 km/h).  The maximum sustained wind speed was 30 m.p.h. (50 km/h).  There were wind gusts to 50 m.p.h. (80 km/h) in some thunderstorms.  The minimum surface pressure was 999 mb.

Bill still has a well organized circulation at the surface and throughout the troposphere.  There is still a warm core in the middle troposphere and divergence in the upper levels.  The upper level divergence pumped out the same amount of mass as converged in the lower levels and the surface pressure remained constant on Wednesday.  Some drier air is wrapping around the southern part of the circulation and most of the rain is falling north and east of the center.  The slow movement of Bill has generated significant amounts of rain and flooding is occurring in some parts of Texas and Oklahoma.  A few thunderstorms have also produced damaging wind gusts.

Bill is expected to turn toward the northeast as is moves around the western end of a high pressure system centered off the southeast coast of the U.S.  It will move slowly across Oklahoma on Thursday and across Arkansas on Friday before moving up the Ohio River Valley during the weekend.

 

Hurricane Carlos Weakening Quickly

It appears from satellite imagery that vertical wind shear quickly weakened Hurricane Carlos on Tuesday night.  At 11:00 p.m. EDT on Tuesday the center of Hurricane Carlos was located at latitude 18.2°N and longitude 104.5°W which put it about 55 miles (90 km) south-southwest of Manzanillo, Mexico.  Carlos was moving toward the northwest at 5 m.p.h. (7 km/h).  The maximum sustained wind speed was 75 m.p.h. (120 km/h) and there were wind gusts to 90 m.p.h. (145 km/h).  The minimum surface pressure was 988 mb.  A Hurricane Watch was in effect for the portion of the coast from Playa Perula to Punta San Telmo, Mexico and a Tropical Storm Warning was in effect for the portion of the coast from Cabo Corrientes to Punta San Telmo, Mexico.

After intensifying on Tuesday afternoon and exhibiting well developed upper level divergence, the structure of Hurricane Carlos degenerated quickly on Tuesday night.  Most of the strong thunderstorms dissipated.  Satellite imagery showed an exposed low level center near the Mexican coast, while the upper level canopy was moving westward away from the low level center.  The decoupling of the upper and low parts of the circulation, usually leads to quick weakening of a hurricane.  The small size of Carlos could allow it to weaken even more quickly than an average hurricane.  The most recent satellite images showed a few thunderstorms forming south of the center of circulation.  However, wind shear caused by an upper level ridge north of Carlos may be too strong to allow for the system to regain its vertical integrity.  Tropical cyclones that are sheared apart sometimes have one chance to redevelop.  The low level center is moving closer to the coast of Mexico and interaction with land may prevent any chance for redevelopment.

If the low level center remains separated from the rest of the system and it does not extend higher into the atmosphere, it will be steered by the winds in the lower levels.  Those winds appear to be taking it north-northwest toward the coast.  Carlos could dissipate quickly if it makes landfall, or the circulation could linger for a day or two if it stays farther offshore.