Monthly Archives: October 2014

Potential Tropical Cyclone Developing Over Bay of Campeche

A reconnaissance plane found a small center of low pressure within a broader area of low pressure over the Bay of Campeche on Tuesday afternoon.  The plane also found winds to near tropical storm force.  At the 3:00 p.m. EDT the low was centered at latitude 19.3°N and longitude 93.7°W which put it about 350 miles northwest of Campeche, Mexico and about 850 miles west-southwest of Key West, Florida.  The low was moving toward the east at 6 m.p.h.  The maximum sustained wind speed was 38 m.p.h. and the minimum surface pressure of 1001 mb.

Thunderstorms are forming mainly on the southern and eastern sides of the center.  The low could be pulling in some of the drier air over the northern Gulf of Mexico, which may be limiting convection on the northwest side of the low.  Westerly winds in the upper levels are also generating wind shear, which is inhibiting the development of the low.  On the other hand, the low is over Sea Surface Temperatures (SSTs) that are warmer than 29°C and there is plenty of energy in the ocean to support the development of a tropical cyclone.  The pressure has fallen about 5-6 mb in the past 12 hours and so the low appears to be getting stronger.  If more thunderstorms form around the center of the low, it could be classified as a tropical depression or a tropical storm.

The westerly winds in the upper and middle levels are pushing the low slowly toward the east.  Guidance from the forecast models seems to be divided into two main possibilities.  One group of models keeps the low relatively weak and forecasts it to move eastward across the Yucatan peninsula and into the northwestern Caribbean Sea before turning it northeastward and moving the low across the Bahamas.  A second group of models predicts that the low will be a bit stronger and that the upper level flow will turn it northeastward sooner and move the low across southern Florida.  If that second scenario occurs, the low could bring stronger winds and heavy rainfall to parts of south Florida.

 

Possible Tropical Development Over Southern Gulf of Mexico

A low pressure system has formed at the surface along the western end of a stationary front over the Bay of Campeche.  It is possible that this low pressure system could intensify into a tropical cyclone and the National Hurricane Center has tasked a reconnaissance plane to investigate the low tomorrow, if necessary.  At 8:00 a.m. EDT on Monday the low was centered at latitude 19.5°N and longitude 95.5°W which put it about 50 miles east of Veracruz, Mexico and about 940 miles west-southwest of Key West, Florida.  The low as moving toward the northeast at 3 m.p.h.  The maximum sustained wind speed was 30 m.p.h. and the minimum surface pressure was 1008 mb.

The low is over Sea Surface Temperatures (SSTs) that are warmer than 29°C and the southern Gulf of Mexico is a location where we see tropical cyclones develop late in the hurricane season.  On the other hand, westerly winds in the upper levels are creating wind shear over the low pressure system and there is drier air over the northern half of the Gulf of Mexico.  Those two factors will inhibit intensification of the system and so tropical development of the low could be slow.  If thunderstorms do develop near the center of the low, it will remain over warm SSTs while it is in the Gulf of Mexico and it could become a tropical storm.

There is westerly flow in the middle and upper levels over the Gulf of Mexico and that flow is likely to push the low pressure system toward the east.  The low could move slowly during a period while it is organizing.  If an area of deep thunderstorms forms, then the middle and upper level winds could push the low eastward more quickly.  The low could approach southwestern Florida later this week.

 

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 Storm Trudy Forms Southeast of Acapulco

A center of circulation formed within a large area of low pressure south of the coast of Mexico and the system has been classified as Tropical Storm Trudy.  At 11:00 p.m. EDT on Friday the center of Tropical Storm Trudy was located at latitude 15.6°N and longitude 99.0°W which put it about 100 miles southeast  of Acapulco, Mexico.  Trudy was moving toward the north at 8 m.p.h.  The maximum sustained wind speed was 40 m.p.h. and the minimum surface pressure was 1005 mb.  The government of Mexico has issued a Tropical Storm Warning for the portion of the coast from Tecpan de Galeana to Laguna de Chacahua.

A high pressure system over the northern Gulf of Mexico is steering Trudy northward and this motion is expected to continue on Saturday.  Trudy is likely to make landfall on the Mexican coast during the next 24 hours.  The greatest risks are from heavy rainfall and flooding.

Trudy is over warm Sea Surface Temperatures and the upper level winds are not strong.  So, the environment is conducive to intensification.  However, the circulation around Trudy will interact with land soon and there is a limited time during which intensification could occur.

There is a possibility that the middle level circulation of Trudy could cross Mexico and interact with a stationary front over the Bay of Campeche to spin up a low pressure system over the southern Gulf of Mexico next week.

Trudy is the first T-named storm to form over the Eastern North Pacific since Tina in 1992.

Ana Reaches Hurricane Intensity Near Hawaii

The structure and internal organization of Tropical Storm Ana has increased during the past 12 hours and it has intensified into a hurricane.  At 5:00 p.m. EDT the center of Hurricane Ana was located at latitude 16.4°N and longitude 155.2°W which put it about 230 miles south of Hilo and about 380 miles south-southeast of Honolulu, Hawaii.  Ana was moving toward the west-northwest at 14 m.p.h.  The maximum sustained wind speed was 75 m.p.h. and the minimum surface pressure was 987 mb.

The high pressure system that was steering Ana toward the west is weakening as an upper level trough approaches from the northwest.  The result of the interaction of the two systems is to steer Ana more toward the northwest.  Guidance from numerical models suggests that the center of Ana could stay south of the Hawaiian islands.  A new high pressure system is expected to build north of Ana and turn it back onto a more westward track in a couple of days.  The timing of that turn could determine how much of an effect Ana has on Hawaii.  A deviation of the track farther to the north would cause Ana to have a greater impact.  Tropical Storm Watches have been issued for Hawaii County, for Maui County including the islands of Maui, Molokai, Lanai and Kahoolwe, for Oahu, and for Kauai County including the islands of Kauai and Niihau.

The wind shear over Ana has decreased and some further intensification is possible.  When the upper level trough gets closer to Ana, the wind shear will increase and the hurricane should start to weaken.

Eyewall of Hurricane Gonzalo Is Rapidly Approaching Bermuda

The northern eyewall of Hurricane Gonzalo is approximately 45 miles (72 km) south-southwest of Bermuda.  The strongest winds in a tropical cyclone are normally found in the eyewall and so the weather conditions over Bermuda are likely to deteriorate rapidly during the next few hours.  At 5:00 p.m. EDT the weather station on Bermuda was reporting easterly winds at 45 m.p.h. with gusts to 67 m.p.h.  Heavy rain was falling and the pressure was falling rapidly.  Based on the current motion of Gonzalo, hurricane force winds could reach Bermuda during the next two or three hours.

At 5:00 p.m. EDT the center of Hurricane Gonzalo was located at latitude 31.7°N and longitude 65.3°W which put it about 50 miles southwest of Bermuda.  The maximum sustained wind speed was 115 m.p.h. and the minimum surface pressure was 949 mb.  A Hurricane Warning remains in effect for Bermuda.  The Canadian Hurricane Center has issued a Tropical Storm Watch that extends from Arnolds Cove to Chapels Cove, Newfoundland.

As of 5:00 p.m. EDT the maximum sustained wind speed in Gonzalo was 115 m.p.h.  Southwesterly winds in the upper levels are creating wind shear over Gonzalo, but it is still likely to strike Bermuda as a major hurricane.  A storm surge and wave action could pose a significant risk to the south coast.  High winds could also do damage, especially to exposed structures at higher elevations.

 

Gonzalo Threatens Bermuda As a Major Hurricane

Hurricane Gonzalo completed an eyewall replacement cycle on Wednesday and it is now stronger than it was.  At 8:00 a.m. EDT on Thursday the center of Gonzalo was located at latitude 25.5°N and longitude 68.7°W which put it about 525 miles south-southwest of Bermuda.  Gonzalo was moving toward the north at 9 m.p.h.  The maximum sustained wind speed was 140 m.p.h. which made Gonzalo a Category 4 hurricane on the Saffir-Simpson Scale.  It had a Hurricane Intensity Index of 28.3, a Hurricane Size Index of 13.9 and a HI of 42.2, which means it was capable of producing regional serious damage.  The minimum surface pressure was 940 mb.  A Hurricane Warning has been issued for Bermuda.

Gonzalo is moving around the western end of a high pressure system located toward its east.  Southwesterly winds on the leading edge of an upper level trough over the eastern U.S. are expected to turn Gonzalo toward the north-northeast.  The stronger winds in the upper level trough will also make Gonzalo start to move faster.  Gonzalo is likely to approach Bermuda on Friday afternoon.

Gonzalo is still in a environment that can support a major hurricane.  It is over warm Sea Surface Temperatures (SSTs) and the upper level winds are relatively light.  When the upper level trough begins to affect Gonzalo, stronger winds will generate more wind shear and the hurricane should begin to weaken.  However, Gonzalo could still be a Major Hurricane when it reaches Bermuda.  After Gonzalo moves north of Bermuda, the weakening trend will continue as cooler SSTs and drier air affect the hurricane.  Gonzalo will make a transition to a strong extratropical cyclone as it moves across the North Atlantic.

Gonzalo is forecast to take a track very similar to the one taken by Hurricane Fabian in 2003.  Fabian was a Major Hurricane that hit Bermuda.  Fabian did much damage to roofs and vegetation and it did an estimated 300 million dollars of property damage.  Winds speeds were greater at higher elevations.  Fabian also generated large waves and a storm surge of ten feet on the south shore of Bermuda.

 

Gonzalo Becomes a Major Hurricane

Hurricane Gonzalo intensified more rapidly on Tuesday and it reached Major Hurricane intensity on Tuesday afternoon.  At 11:00 p.m. EDT the center of Hurricane Gonzalo was located at latitude 22.2°N and longitude 66.6°W which put it about 705 miles south of Bermuda.  Gonzalo was moving toward the northwest at 13 m.p.h.  The maximum sustained wind speed was 125 m.p.h., which made Gonzalo a Category 3 hurricane on the Saffir-Simpson Scale.  The minimum surface pressure was 954 mb.  Gonzalo is now the strongest Atlantic hurricane so far in 2014.  A Hurricane Watch has been issued for Bermuda.

Gonzalo is still being steered by the subtropical high pressure system.  As it reaches the western end of the high, it will turn more toward the north.  Numerical models continue to indicate that southwesterly winds on the eastern side of a large upper trough moving over the eastern U.S. will turn Gonzalo toward the northeast later this week.  Gonzalo could be approaching Bermuda by Friday.

A smaller upper low located west of Gonzalo is creating some wind shear over the hurricane, but clearly the shear did not inhibit rapid intensification on Tuesday.  Gonzalo will be moving over warm Sea Surface Temperatures and so some further intensification is possible.  There could be some fluctuations in intensity if an eyewall replacement cycle starts to develop.  Eventually, the same upper level trough that should turn Gonzalo toward the northeast will generate stronger upper level winds and more wind shear.  Current guidance indicates that Gonzalo will still be a hurricane when it approaches Bermuda.

 

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.