Monthly Archives: November 2015

Tropical Storm In-Fa Near Fananu, Watch Issued for Guam

Tropical Storm In-Fa is near Fananu and it is bringing wind and rain to islands around Chuuk.  At 10:00 p.m. EST on Wednesday the center of Tropical Storm In-Fa was located near latitude 8.6°N and longitude 152.0°E which put it about 25 miles (40 km) southeast of Fananu and about 620 miles (1000 km) southeast of Guam.  In-Fa was moving toward the northwest at 15 m.p.h. (24 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 982 mb.

A Tropical Storm Watch has been issued for Guam.  A Typhoon Warning is in effect for Chuuk lagoon, Losap, Ulul and Fananu.

In-Fa was briefly a typhoon earlier on Wednesday when it had a small, but well formed eye.  However, the core of In-Fa weakened slightly and the eye filled with clouds.  A small, but circular, area of thunderstorms has intensified in the core of the tropical storm during the past few hours.  There are signs that In-Fa may be strengthening again.  The environment surrounding Tropical Storm In-Fa is favorable for intensification.  It is over water where the Sea Surface Temperature is near 29.5°C.  The upper level winds are light and the vertical wind shear is modest.  In-Fa could regain typhoon intensity on Thursday and a period of rapid intensification may be possible once the inner core reorganizes.

A subtropical ridge north of In-Fa is steering the tropical storm toward the northwest and that general motion is expected to continue for another two or three days.  On its anticipated track the center of In-Fa will pass near Fananu during the next few hours.  In-Fa could be south of Guam in about 48 hours.

Poorly Organized Tropical Depression 21E Forms West of Mexico

A low level circulation center formed in a cluster of thunderstorms west of Mexico and the National Hurricane Center decided it had enough organization to be classified as a tropical depression.  At 10:00 p.m. EDT on Wednesday the center of Tropical Depression 21E (TD21E) was located at latitude 13.2°N and longitude 106.1°W which put it about 420 miles (675 km) south-southwest of Manzanillo, Mexico.  TD21E was moving toward the north at 2 m.p.h. (3 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 1004 mb.

TD21E looked more well organized earlier today when the low level center of circulation was located within the area of thunderstorms.  The low level center is now southeast of an area of weakening thunderstorms, which is an indication that the tropical depression is poorly organized.  Most of the remaining thunderstorms are located north of the low level center.

The tropical depression is over water where the Sea Surface Temperature is near 30°C.  However, the environment is not really favorable for intensification.  An upper level ridge east of the depression is causing southerly winds over the top of TD21E.  Those winds are generating vertical wind shear over the top of the depression.  The wind shear has blown the thunderstorms north of circulation center.  Some slight intensification may be possible if the wind shear decreases, but the poor organization of the depression will limit any potential strengthening.

If the tropical depression retains its vertical integrity, the southerly winds in the upper levels should push it toward the north.  However, if the wind shear blows the thunderstorms farther north of the low level center of circulation, then the low level center could remain stationary while it spins down.

Tropical Storm In-Fa Intensifying, Typhoon Watch for Fananu

Tropical Storm In-Fa intensified quickly on Tuesday and it caused watches and warnings to be issued for the area around Chuuk.  At 10:00 p.m. EST on Tuesday the center of Tropical Storm In-Fa was located at latitude 6.0°N and longitude 156.3°E which put it about 385 miles (620 km) east-southeast of Fananu and about 985 miles (1590 km) east-southeast of Guam.  In-Fa was moving toward the west-northwest 18 m.p.h. (29 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 983 mb.  A Typhoon Watch has been issued for Fananu.

The circulation of Tropical Storm In-Fa organized rapidly on Tuesday.  A tight core formed in the center of circulation and an eyelike feature appeared on satellite images.  A small ring of thunderstorms formed around the eye and a large primary rainband wrapped around the circulation.  The circulation became more symmetrical and upper level outflow began to create divergence in most directions.

Tropical Storm In-Fa remains in an environment favorable for intensification.  It is over water where the Sea Surface Temperature is near 30°C.   The upper level winds are light and the vertical wind shear is modest.  In-Fa is likely to continue to intensify and now that an inner core has developed, it could intensify rapidly.  In-Fa could become a typhoon on Wednesday and it could become the equivalent of a major hurricane later this week.

A subtropical ridge north of In-Fa is steering the tropical storm toward the west-northwest and that general motion is expected to continue for the rest of the week.  On its anticipated track In-Fa will approach Fananu in about 24 hours and it could be a typhoon at that time.  In-Fa could be approaching Guam in about three days as a typhoon.

Tropical Depression 27W Forms Southeast of Pohnpei

A center of circulation formed in an area of thunderstorms southeast of Pohnpei and the system was designated Tropical Depression 27W (TD 27W).  At 10:00 p.m. EST on Monday the center of Tropical Depression 27W was located at latitude 4.7°N and longitude 162.3°E which put it about 360 miles (585 km) east-southeast of Pohnpei.  TD 27W was moving to the west at 17 m.p.h. (27 km/h).  The maximum sustained wind speed was 30 m.p.h. (50 km/h) and there were gusts to 40 m.p.h. (65 km/h).  The minimum surface pressure was 1001 mb.

The circulation of TD 27W is still organizing.  A clearly defined low level center of circulation formed near the northern edge of an area of thunderstorms.  However, most of the stronger thunderstorms are southwest of the center.  Those storms are generating upper level divergence that is expanding south and west of the center.

Tropical Depression 27W is in an environment that favors further intensification.  It is over water where the Sea Surface Temperature is near 30°C.  An upper level ridge north of TD 27W is producing light easterly winds over the top of the depression.  The vertical wind shear is modest, and it should only slow the rate of intensification.  Intensification could be slow initially as a stronger inner core forms around the center of circulation.  Once the core of the circulation consolidates, then intensification could occur more quickly.  TD 27W could become a tropical storm within 24 to 36 hours and it could be a typhoon in three or four days.

A subtropical ridge north of TD 27W is steering the depression toward the west.  A gradual turn toward the west-northwest is expected and that general motion is expected to continue for much of the week.  On its anticipated track TD 27W could be near Pohnpei in about 24 hours and it could bring tropical storm force winds and heavy rain.  The tropical cyclone could be approaching Guam by the end of the week and it could be a typhoon by that time.

Kate Becomes a Hurricane As It Races Northeast

Kate intensified into the fourth Atlantic hurricane of 2015 as it raced northeastward.  At 10:00 a.m. EST on Wednesday the center of Hurricane Kate was located at latitude 36.8°N and longitude 60.5°W which put it about 395 miles (635 km) northeast of Bermuda and about 780 miles (1160 km) south-southwest of Cape Race, Newfoundland.  Kate was moving toward the northeast at 45 m.p.h. (72 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 985 mb.

The organization of Hurricane Kate improved on Wednesday when a partial eyewall wrapped around the northern and western sides of the center of circulation.  The structure of Kate is somewhat tilted toward the northeast by stronger southwesterly wind in the upper levels of the atmosphere.  However, Kate currently has a warm core and it is still a tropical cyclone.  Kate is moving over water where the Sea Surface Temperature (SST) is near 25°C.  In a day or so the effects of strong vertical wind shear and cooler SSTs will cause Hurricane Kate to begin a transition to an extratropical cyclone.

Strong westerly winds are steering Kate rapidly toward the northeast and that general motion is expected to continue during the next few days.  Kate could approach the United Kingdom as a strong extratropical cyclone during the weekend.

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.

Tropical Storm Kate Intensifies and Moves Away from the Bahamas

Tropical Depression 12 intensified Monday into Tropical Storm Kate.  Kate continued to intensify on Monday night as it started to move away from the Bahamas.  At 10:00 p.m. EST on Monday the center of Tropical Storm Kate was located at latitude 27.2°N and longitude 76.0°W which put it about 175 miles (280 km) north-northeast of the Northwestern Bahamas.  Kate was moving toward the north at 16 m.p.h. (26 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 1005 mb.

Kate is more organized this evening and it looks more like a tropical storm.  The is a core of thunderstorms at the center of circulation and several rainbands are wrapping around the northeastern side of the storm.  Kate has a small circulation and tropical storm force winds only extend out about 80 miles (130 km) on the eastern side of it.  The thunderstorms in the core of Kate are generating upper level divergence which is spreading northeast of the center.

Tropical Storm Kate is in an environment that is favorable for further intensification.  It is over water where the Sea Surface Temperature is near 28°C.  The combination of a large trough west of Kate and a smaller upper level high east of it are creating some southerly winds over the top of the circulation.  However, the vertical wind shear is moderate at the current time, and Kate could intensify further.  Kate could reach hurricane intensity in the next 24 to 36 hours.  After that time the trough to the west of Kate will cause increased vertical wind shear.

The upper level trough and ridge are steering Kate toward the north.  As Kate moves farther north, stronger westerly winds will begin to push it toward the northeast.  Since Kate is moving toward the northeast away from the Bahamas, the government there has discontinued all tropical storm warnings.

Tropical Cyclone Megh Hits Socotra Island and Brushes Somalia

Tropical Cyclone Megh moved over Socotra Island, Yemen on Sunday and it passed near the northeast coast of Somalia.  At 10:00 p.m. EDT on Sunday the center of Tropical Cyclone Megh was located at latitude 12.3°N and longitude 50.6°E which put it about 375 miles (605 km) east of Aden (Adan), Yemen and about 35 miles (55 km) north of Cape Guardafui, Somalia.  Megh was moving toward the west at 13 m.p.h. (21 km/h).  The maximum sustained wind speed was 105 m.p.h. (170 km/h) and there were wind gusts to 125 m.p.h. (200 km/h).  The minimum surface pressure was 957 mb.

Although Tropical Cyclone Megh weakened as it moved across Socotra Island, it remains a small, well organized storm.  Megh still has an eye surrounded by a ring of strong thunderstorms.  Those storm are generating upper level divergence which is pumping out mass in all direction.

Tropical Cyclone Megh is over warm water and the upper level winds are light.  The only negative factors are the proximity to Somalia and drier air over the Arabian peninsula.  As long as the center of Tropical Cyclone Megh stays north of Somalia, it will likely retain most of its intensity.  When Megh starts to get closer to the coast of Yemen, it will begin to draw in some drier air and weaken more rapidly.  Vertical wind shear could also increase in 24 to 36 hours, which would further speed the weakening process.

A subtropical ridge has been steering Megh toward the west and that general motion is expected to continue for another day or so.  After that time Megh will reach the western end of the ridge and start to move toward the northwest.  On its expected track, Tropical Cyclone Megh could approach the coast of Yemen on Tuesday.  It could still be the equivalent of a hurricane at that time.

Tropical Cyclone Megh may have caused significant damage on Socotra Island.  It will be capable of producing wind damage when it reaches Yemen, but heavy rain and flooding will be the greater risk.

Tropical Depression 12 Forms and Warnings Issued for the Bahamas

A small center of circulation developed within a larger disturbance near the Bahamas and the National Hurricane Center classified it as Tropical Depression 12 (TD12).  At 10:00 p.m. EDT on Sunday the center of Tropical Depression 12 was located at latitude 23.0°N and longitude 73.0°W which put it about 115 miles (185 km) southeast of San Salvador in the Bahamas and about 30 miles (50 km) north of Mayaguana.  TD12 was moving toward the 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. (75 km/h).  The minimum surface pressure was 1010 mb.

Tropical Storm Warnings have been issued for the Central and Northwestern Bahamas and for the Acklins, Samana Cays, Crooked Island and Long Cay in the Southeastern Bahamas.

Tropical Depression 12 formed when a tropical wave interacted an upper level low.  Tropical cyclones that develop in that manner tend to be poorly organized in their early stages.  Most of the stronger thunderstorms are located east and south of the center of circulation.  The surface center is located on the western edge of the convection.

Although Tropical Depression 12 is over water where the Sea Surface Temperature is near 28°C, the upper level environment is marginal for intensification.  An upper level low near southwest of the depression is generating southerly upper level winds over the western part of TD12.  A small upper level high is over the eastern part of TD12.  The upper level high is generating some divergence to the east of the depression.  Some further intensification is possible and the depression could become Tropical Storm Kate on Monday.

Tropical Depression 12 could bring rain and squally weather to parts of the Bahamas.  It is near some of the same places that were hit by Hurricane Joaquin last month and it could hinder recovery efforts.

Dangerous Tropical Cyclone Megh Nearing Socotra Island

Megh intensified rapidly Saturday into a dangerous tropical cyclone as it neared Socotra Island, Yemen.  At 10:00 p.m. EDT on Saturday the center of Tropical Cyclone Megh was located at latitude 12.8°N and longitude 55.5°E which put it about 105 miles (170 km) east of Socotra Island, Yemen.  Megh was moving toward the west at 13 m.p.h. (21 km/h).  The maximum sustained wind speed was 130 m.p.h. (210 km/h) and there were wind gusts to 150 m.p.h. (240 km/h).  The minimum surface pressure was 939 mb.

Tropical Cyclone Megh is the equivalent of a major hurricane even though it is a small storm.  Megh is a very symmetrical cyclone.  It has a five mile (8 km) wide eye which is surrounded by a ring of strong thunderstorms.  The convection in the core is generating upper level divergence which in pumping out mass.  Tropical storm force winds extend out 50 miles (80 km) from the center.

Tropical Cyclone Megh will remain in a favorable environment until it reaches Socotra Island.  It is over water where the Sea Surface Temperature is near 28°C.  The upper level winds are light and there is vertical wind shear.  Megh could intensify further until it reaches Socotra.  It should weaken when the core of the circulation interacts with island.

A subtropical ridge north of Megh is steering the tropical cyclone toward the west and that general motion is expected to continue for several more days.  On its anticipated track Tropical Cyclone Megh will reach Socotra Island in a few hours.  it is capable of producing wind damage and flooding.  Since Tropical Cyclone Chapala recently caused damage on Socotra, the impact of Tropical Cyclone Megh could be significant.