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Subtropical Storm Alberto Forms Over Northwest Caribbean Sea

Subtropical Storm Alberto formed over the northwestern Caribbean Sea on Friday morning.  The National Hurricane Center (NHC) designated an area of low pressure as Subtropical Storm Alberto on Friday morning based on data from buoys and ship reports.  At 5:00 p.m. EDT on Friday the center of Subtropical Storm Alberto was located at latitude 19.4°N and longitude 86.3°W which put it about 85 miles (135 km) south-southeast of Cozumel, Mexico.  Alberto was moving toward the east 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.

A Tropical Storm Watch has been issued for the portion of the U.S. coast from Indian Pass, Florida to Grand Isle, Louisiana including New Orleans.  The government of Mexico issued a Tropical Storm Watch for the portion of the coast from Tulum to Cabo Catoche.  The government of Cuba issued a Tropical Storm Watch for the province of Pinar del Rio.

The circulation around Subtropical Storm Alberto was asymmetrical.  The low level center of circulation was located just to east of the Yucatan Peninsula.  The strongest thunderstorms were occurring in a band located about 100 miles (160 km) east and north of the center.  Flow around an upper level trough over the Gulf of Mexico was producing westerly winds which were blowing toward the top of the circulation.  Those winds were causing strong vertical wind shear which was the reason why the thunderstorms were occurring well to the east of the center of circulation.

Subtropical Storm Alberto will move through an environment marginally favorable for intensification during the next 24 to 36 hours.  Alberto will move over water where  the Sea Surface Temperature is near 28°C.  So, there is sufficient energy in the upper ocean to support intensification.  However, the upper level trough will continue to cause moderate to strong vertical wind shear during the next day or so.  The wind shear will inhibit intensification.  Some gradual strengthening is possible.  The winds are weaker near the axis of the upper level trough.  If Alberto moves under the axis of the trough when it reaches the northern Gulf of Mexico, then the wind shear will decrease.  Alberto could strengthen more quickly if that happens.  There is a chance that Alberto could reach hurricane intensity.  If more thunderstorms form closer to the center of circulation, then NHC could change the designation of Alberto to a tropical storm.

Subtropical Storm Alberto is moving around the western end of a large high pressure system over the Atlantic Ocean.  The high is steering Alberto slowly toward the north-northeast.  A general motion toward the north is forecast during the next day or so.  When Alberto gets farther north, the upper level trough could steer it more toward the north-northwest.  There is a chance that the steering currents could weaken when Alberto nears the Gulf Coast.  Thus, there is much more uncertainty about the track forecast after that time.

The greatest risk with Subtropical Storm Alberto will be locally heavy rain and the potential for flooding.  Most of the heavy rain is likely to fall north and east of the center.  Much less rain is likely to fall from the western side of Alberto.  The coast of the Gulf of Mexico is very susceptible to storm surges.  The water level will rise along the eastern and northern coasts of the Gulf of Mexico where the winds blow the water toward the shoreline.

Tropical Cyclone Nora Strengthens Over Gulf of Carpentaria

Tropical Cyclone Nora strengthened over the Gulf of Carpentaria on Friday.  At 11:00 p.m EDT on Friday the center of Tropical Cyclone Nora was located at latitude 12.6°S and longitude 140.0°E which put it about 125 miles (205 km) west of Weipa, Australia.  Nora was moving toward the southeast at 9 m.p.h. (14 km/h).  The maximum sustained wind speed was 110 m.p.h. (175 km/h) and there were wind gusts to 130 m.p.h. (210 km/h).  The minimum surface pressure was 956 mb.  The Australian Bureau of Meteorology had issued a Warning for the portion of the coast from Karumba to Mapoon including Weipa and Mornington Island.  A Watch was in effect for the portion of the coast from Weipa to the border between the Northern Territory and Queensland.

Tropical Cyclone Nora strengthened on Friday as it entered the northern portion of the Gulf of Carpentaria.  An eye appeared intermittently at the center of circulation.  A band of stronger thunderstorms wrapped intermittently around the formative eye and the strongest winds were blowing in the band of thunderstorms.  Bands of showers and thunderstorms were revolving around the center of circulation.  Storms near the core of the circulation were generating upper level divergence which was pumping mass away from the tropical cyclone.

Tropical Cyclone Nora will be moving through an environment favorable for intensification.  Nora will move over water where the Sea Surface Temperature is near 30°C.  It will move under an area where the upper level winds are weak and there is little vertical wind shear.  Tropical Cyclone Nora could strengthen into the equivalent of a major hurricane during the next 24 to 36 hours.

Tropical Cyclone Nora is moving near the western end of a mid-level ridge which is steering Nora toward the south.  A general motion toward the south is expected to continue for another day or two.  On its anticipated track Nora could approach the coast of Queensland between Kowanyama and the mouth of the Gilbert River in 24 to 36 hours.  Nora could bring gusty winds and locally heavy rain to portions of northwestern Queensland.

Elsewhere, Tropical Cyclone Marcus was weakening off the coast of Western Australia.  At 11:00 p.m. EDT on Friday the center of Tropical Cyclone Marcus was located at latitude 25.9°S and longitude 107.5°E, which put it about 770 miles (1045 km) west of Carnarvon, Australia.  Marcus was moving toward the south-southeast at 20 m.p.h. (32 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 984 mb.

Tropical Cyclone Ernie Very Rapidly Intensifies Into Equivalent of a Major Hurricane

Tropical Cyclone Ernie intensified very rapidly into the equivalent of a major hurricane during the past few hours.  Ernie strengthened from a tropical low to the equivalent of a major hurricane in one day which is an extremely rapid rate of intensification.  At 8:00 a.m. EDT on Friday the center of Tropical Cyclone Ernie was located at latitude 15.5°S and longitude 110.2°E which put it about 485 miles (780 km) north-northwest of Exmouth, Australia.  Ernie was moving toward the south at 6 m.p.h. (10 km/h).  The maximum sustained wind speed was 125 m.p.h. (200 km/h) and there were wind gusts to 175 m.p.h. (290 km/h).  The minimum surface pressure was 936 mb.

Tropical Cyclone Ernie is a very small well organized storm.  It has a small eye surrounded by a ring of very strong thunderstorms.  The strongest winds are occurring in the ring of storms around the eye.  Additional bands of thunderstorms are revolving around the core of Ernie.  The thunderstorms in the core of Tropical Cyclone Ernie are generating strong upper level divergence which is pumping out mass and caused the surface pressure to decrease very rapidly.  Winds to hurricane/typhoon force extend out about 18 miles (30 km) from the center of circulation.  Winds to tropical storm force extend out about 90 miles (150 km) from the center.

The Hurricane Intensity Index (HII) for Tropical Cyclone Ernie is 23.6.  The Hurricane Size Index (HSI) is 7.8 and the Hurricane Wind Intensity Size Index (HWISI) is 31.4.  Those indices indicate that Tropical Cyclone Ernie is capable of causing localized significant damage.

Tropical Cyclone Ernie is in an environment favorable for tropical cyclones.  It is moving over water where the Sea Surface Temperature (SST) is near 30°C.  An upper level ridge centered southeast of Ernie is producing northerly winds which are blowing toward the tropical cyclone but the vertical wind shear is currently having no effect on it.  Tropical Cyclone Ernie could intensify more during the next 12 hours.  Ernie will move into an area of cooler SSTs and stronger vertical winds in a day or so.  The less favorable environment will cause Tropical Cyclone Ernie to weaken.  Tropical Cyclone Ernie could weaken quickly because of its small size, if the vertical wind shear increases rapidly.

A subtropical ridge southeast of Ernie is steering the tropical cyclone slowly toward the south.  The ridge is forecast to strengthen and extend toward the west.  When the ridge strengthens it is likely to steer Tropical Storm Ernie more toward the west.  On its anticipated track Tropical Cyclone Ernie poses no current threat to land.

Tropical Cyclones Winston and Tatiana Form over SW Pacific

A pair of tropical cyclones named Winston and Tatiana formed over the southwestern Pacific Ocean on Thursday.  At 10:00 p.m. EST on Thursday the center of Tropical Cyclone Winston was located at latitude 18.4°S and longitude 171.6°E which put it about 445 miles (720 km) west of Suva, Fiji.  Winston was moving toward the south at 7 m.p.h. (11 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 974 mb.

At 10:00 p.m. EST on Thursday the center of Tropical Cyclone Tatiana was located at latitude 17.3°S and longitude 159.0°E which put it about 620 miles (1000 km) northwest of Noumea, New Caledonia.  Tatiana was moving toward the east-southeast 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 982 mb.

Tropical Cyclone Winston is the stronger and more well organized storm.  It has a well developed eye surrounded by a ring of strong thunderstorms.  Winston is in a very favorable environment.  It is moving over water where the Sea Surface Temperatures are near 31°C.  There is an upper level ridge over Winston and so the upper level winds are light and divergence is occurring in all directions.  Winston is likely to continue to intensify rapidly on Friday and it could become the equivalent of a major hurricane.

Tropical Cyclone Tatiana is smaller and not as well organized.  Tatiana is moving over water where the Sea Surface Temperatures are near 30°C.  However the western end of the same upper level ridge that is over Winston is generating brisk northerly winds over the top of Tropical Cyclone Tatiana.  As a result, vertical wind shear is inhibiting upper level divergence to the north of the center of Tatiana and it is also tilting the circulation toward the south with height.  Wind shear is likely to prevent Tatiana from intensifying significantly.

A subtropical ridge is steering both Winston and Tatiana toward the south.  Tropical Cyclone Winston will pass west of Fiji, but it could come close enough to the extreme southeastern islands of Vanuatu to bring wind and rain to some of those islands.  Tropical Cyclone Tatiana is likely to pass west of New Caledonia, but it could bring rain and higher surf to the west coast of that island.

Weaker Tropical Cyclone Megh Close to Landfall in Yemen

Drier air from the Arabian peninsula finally entered the circulation of Tropical Cyclone Megh and most of the convection weakened on Monday.  At 10:00 p.m. EDT on Monday the center of Tropical Cyclone Megh was located at latitude 13.0°N and longitude 47.0°E which put it about 150 miles (240 km) east of Aden (Adan), Yemen.  Megh 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 990 mb.

As Tropical Cyclone Megh moved closer to the coast of Yemen, it began to draw in drier air from the Arabian peninsula.  As the drier air penetrated the circulation, it cut off the energy from the convection and most of the thunderstorms dissipated.  Without a continuous supply of new energy Megh weakened and the wind speeds decreased.  As the center of circulation approached the coast, friction over land increased low level convergence and new thunderstorms formed near the center.  Those storms are producing winds to tropical storm force over the Gulf of Aden.

Tropical Cyclone Megh is moving around the western end of a subtropical ridge.  The ridge is steering Megh toward the west-northwest.   Tropical Cyclone Megh will make landfall near Ahwar, Yemen in a few hours.  It is still capable of producing locally heavy rain and causing flash flooding.

Typhoon Soudelor Making Landfall in China

Typhoon Soudelor crossed the Taiwan Strait and it is making landfall on the east coast of China near Quanzhou.  At 11:00 a.m. EDT on Saturday the center of Typhoon Soudelor was located at latitude 24.9°N and longitude 118.9°E which put it about 50 miles east of Quanzhou.  Soudelor was moving to the northwest at 10 m.p.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 974 mb.

Soudelor weakened when it moved across Taiwan on Friday, but it was still a large typhoon when it made landfall in China.  Soudelor is expected to move toward the northwest while it moves farther inland over China.  Soudelor produced heavy rain when it moved over Taiwan and it could cause locally heavy rainfall over parts of eastern China before it dissipates.

Tropical Storm Mekkhala Develops East of the Philippines

Tropical Depression 01W intensified into Tropical Storm Mekkhala on Wednesday.  At 11:00 p.m. EST on Wednesday the center of Tropical Storm Mekkhala was located at latitude 11.5°N and longitude 133.8°E which put it about 370 miles north-northwest of Palau and about 820 miles east of Manila, Philippines.  Mekkhala was moving toward the west at 16 m.p.h.  The maximum sustained wind speed was 40 m.p.h. and there were gusts to 60 m.p.h.   The minimum surface pressure was 1000 mb.

Although there are still moderate wind speeds in the upper levels, the wind shear decreased slightly.  That allowed more thunderstorms to develop closer to the center of circulation and the system became more organized.  A subtropical ridge northeast of Mekkhala will continue to produce southeasterly winds over the top of the circulation.  Moderate wind shear will limit intensification.  However, Mekkhala will be moving over Warm Sea Surface Temperatures and so some intensification is possible during the next several days.

The subtropical ridge is expected to strengthen and steer Mekkhala westward toward the Philippines.  The tropical storm could be approaching the central and northern Philippines in 48 to 72 hours.  The main threats appear to be locally heavy rainfall, flooding and mudslides.

 

Hurricane Ana Passing South of Oahu

Although Hurricane Ana is bringing rain to some of the Hawaiian Islands, the core of the storm is passing south of Oahu.  At 11:00 p.m. EDT on Saturday the center of Hurricane Ana was located at latitude 19.9°N and longitude 159.2°W which put it about 130 miles southwest of Honolulu and about 145 miles south of Lihue.  Ana was moving toward the northwest at 8 m.p.h.  The maximum sustained wind speed was 80 m.p.h. and the minimum surface pressure was 987 mb.  A Tropical Storm Warning has been issued for Kauai County including the islands of Kauai and Niihau.  A Tropical Storm Watch remains in effect for Oahu.

A ridge of high pressure that was steering Ana more toward the west is weakening and the hurricane is moving more toward the northwest.  As the steering winds have weakened, the forward speed of Ana has decreased.  Eventually, another ridge of high pressure is expected to build north of Ana and make it turn more toward the west-northwest again.  The Tropical Storm Warning for Kauai was issued as a precaution in case the turn toward the west-northwest is delayed.

An upper level trough northwest of Ana is generating wind shear over the top of the hurricane.  However, the structure has remained relatively intact and a reconnaissance plane found winds to 80 m.p.h. in the northwestern portion of the eyewall.  The intensity of Ana may fluctuate during the next few days as shear increases and decreases.

 

Tropical Depression Two-C Forms East-Southeast of Hawaii

A center of circulation has formed within a broad east-west trough of low pressure about a thousand miles east-southeast of Hawaii.  The Central Pacific Hurricane Center has classified the system as Tropical Depression Two-C and has begun issuing advisories on it.  At 5:00 p.m. EDT the center of Tropical Depression Two-C (TD2C) was located at latitude 12.8°N and longitude 143.2°W which put it about 915 miles east-southeast of Hilo and about 1135 miles east-southeast of Honolulu, Hawaii.   TD2C was moving toward the west-northwest at 11 m.p.h.  The maximum sustained wind speed was 35 m.p.h. and the minimum surface pressure was 1007 mb.

A ridge of high pressure north of TD2C is likely to continue to steer it in a general west-northwesterly direction for the next few days.  An upper level trough may approach the system from the west late in the week and turn the tropical cyclone more toward the northwest.   TD2C could approach Hawaii by the end of the week or early this weekend.

TD2C is over Sea Surface Temperatures (SSTs) that are warmer than 28°C.  The circulation is becoming more well organized and the upper level winds are not very strong.  TD2C is likely to intensify and if it becomes a tropical storm it will get the name Ana.  The SSTs closer to Hawaii are a little cooler, but they are still warm enough to support a tropical cyclone.  Thus, TD2C could intensify into a hurricane as it moves in the general direction of Hawaii.

 

Tropical Storm Gonzalo Forms East of Leeward Islands

A small area of low pressure east of the Leeward Islands displayed increased organization today and a reconnaissance plane found that it had winds to tropical storm force.  Based on that information the National Hurricane Center classified the low as Tropical Storm Gonzalo.  At 1:30 p.m. EDT the center of Gonzalo was located at latitude 16.4°N and longitude 58.4°W which put it about 200 miles east of Guadaloupe and about 230 miles east-southeast of Antigua.  Gonzalo was moving toward the west at 10 m.p.h.  The maximum sustained wind speed was 40 m.p.h. and the minimum surface pressure was 1009 mb.

Tropical Storm Warnings have been issued for Guadaloupe, Les Saintes, Maria Galante, St. Martin, St. Barthelemy, St. Maartin, Saba, St. Eustatius, Barbuda, Antigua, Anguilla, St. Kitts, Nevis, and Montserrat.  Tropical Storm Watches have been issued for Puerto Rico, Vieques, Culebra, the U.S. Virgin Islands and the British Virgin Islands.

Gonzalo is begin steered westward by a subtropical high pressure system located north of it.  Gonzalo is likely to continue moving westward for another day or so until it nears the western end of the subtropical high.  At that point it is likely to turn more toward the northwest and then eventually start moving northward.  The numerical models are currently predicting that a large trough over the western U.S. will move eastward and turn Gonzalo toward the northeast as it moves north of Puerto Rico.

Gonzalo is currently experiencing some shear from the west.  However, it is over water where the Sea Surface Temperatures are near 29°C.  So, intensification is likely.  Gonzalo is a small tropical storm and small tropical cyclones can intensify or weaken more rapidly than larger storms.   A period of rapid intensification is possible if the shear diminishes a little more.   Gonzalo could become a hurricane before it gets to Puerto Rico.