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Hurricane Season 2005: Tropical Depression #27
11.18.05
 
Tropical Storm Gamma Brings Flooding to Honduras

TRMM image of Gamma on November 14, 2005.The pace of the 2005 hurricane season is finally slowing down, but the season is not yet over as evidenced by the record twenty-fourth named storm of the season-- Tropical Storm Gamma. The twenty-seventh tropical depression of the season formed on 13 November 2005 from an area of low pressure in the southeastern Caribbean. The Tropical Rainfall Measuring Mission (TRMM) satellite captured these images of Tropical Depression #27 at 6:37 am EST on 14 November 2005 when the system was in the far southeastern Caribbean just west of the Windward Islands.

The first image (right) shows a top-down-view of the rainfall pattern associated with TD #27 as obtained from TRMM's sensors. Rain rates in the center of the swath are from the TRMM Precipitation Radar (PR), the only radar able to measure precipitation from space. Rain rates in the outer swath are from the TRMM Microwave Imager (TMI). The rain rates are overlaid on infrared (IR) data from the TRMM Visible Infrared Scanner (VIRS). TRMM shows the system is still in the process of organizing with no eye and little evidence of curvature in the rain field.

TRMM captures a 3D image of Gamma on November 14, 2005.However, the next image (left), taken at the same time, shows a 3D perspective of the system courtesy of the TRMM PR. The PR reveals areas of deep convection as evidenced by the tall towers (shown in red). When these towers occur near the center of the circulation, it is usually a sign that the system is about to strengthen. However, TD #27 was also encountering westerly wind shear, which was impeding its development. At the time of these images, TD #27 had sustained winds estimated at 30 knots (35 mph) by the National Hurricane Center (NHC).

As the system moved west through the central Caribbean, it continued to encounter unfavorable shear and temporarily fell apart. On 18 November, however, the remnants of TD #27 re-organized over the western Caribbean into Tropical Storm Gamma just to the north of Honduras. Gamma drifted erractically over the next two days, essentially remaining in place.

Tropical Storm Gamma seen by TRMM on November 19, 2005.TRMM captured this image (right) of Gamma at 8:59 pm EST 18 November as it was drifting right along the northern coast of Honduras with sustained winds reported at 40 knots (46 mph) by NHC. The circulation is still poorly organized with no obvious curvature in the rain bands. However, a large area of heavy (red areas) to moderate rain (green areas) extends north of the center. And although Gamma did not intensify (which is consistent with absence of any deep convection near the center at this time), the storm brought heavy rains and flooding to Honduras.









Movement of Gamma from November 14 to 21.The TRMM-based, near-real time Multi-satellite Precipitation Analysis (MPA) at the NASA Goddard Space Flight Center provides estimates of rainfall over the global Tropics. MPA rainfall totals are shown (left) for the period 14 to 21 November 2005 with storm symbols marking the track Gamma. Rainfall totals of 6 (green) to 10 (yellow) inches are evident along the northern coast of Honduras. So far, 32 fatalities have been reported in Honduras as a result of flooding and mudslides with many still missing. Five fishermen from neighboring Belize were also missing. Click on image to view animation. TRMM is a joint mission between NASA and the Japanese space agency JAXA. Images produced by Hal Pierce (SSAI/NASA GSFC) and caption by Steve Lang (SSAI/NASA GSFC).




Tropical Depression Gamma Fizzles

On Sunday, Nov. 20, at 10:00 p.m. ET, the National Hurricane Center (NHC) issued the final advisory on Tropical Storm Gamma. At that time, Gamma dissipated north of Honduras.

Gamma had been downgraded to a tropical depression with maximum sustained winds of 30 mph, and was located near 17.2 north and longitude 85.5 west or 95 miles north of Limon, Honduras. Since that time, Gamma has dissipated.

Eyes Move Elsewhere for Storm Formation

On Tuesday, Nov. 22, the National Hurricane Center issued a tropical weather outlook that indicated a strong and large non-tropical low pressure system over the north Atlantic was gradually acquiring tropical characteristics. It was centered about 900 miles west-southwest of the Azores Islands. The NHC indicated that it could become a tropical storm at any time.




Tropical Depression Regenerates Quickly and Becomes Tropical Storm Gamma!

Tropical Depression 27 has been a challenge for forecasters, and after fizzling out on Wednesday, Nov. 16 with the loss of closed circulation, it has re-intensified into a tropical storm on the afternoon of Nov. 18 and been named Gamma.

Tropical storm GAMMAImage to left: The National Hurricane Center's predicted track for Tropical Storm Gamma. Click image to enlarge. Credit: NOAA/NHC

Five day forecast projections from the National Hurricane Center take the storm from the western Caribbean into the Gulf of Mexico and making landfall in southwestern Florida sometime on Monday, Nov. 21 before crossing the state and exiting into the Atlantic Ocean.

At 4 p.m. EST on Nov. 18, the broad and poorly defined center of Tropical Storm Gamma was located near latitude 16.4 north and longitude 85.6 west or about 40 miles (65 km) north of Limon, Honduras. Gamma is moving erratically toward the west-northwest near 5 mph (7 km/hr). Maximum sustained winds are near 40 mph (65 km/hr) with higher gusts. Some slow strengthening is forecast during the next 24 hours. Estimated minimum central pressure is 1006 millibars.

Tropical Storm Gamma is expected to produce total rainfall accumulations of 6 to 10 inches over Belize western Cuba and the eastern Yucatan peninsula of Mexico with isolated maximum amounts of 15 inches. Additional rainfall amounts of 4 to 8 inches with isolated maximum amounts of 12 inches are possible over northwestern Honduras.


Tropical Depression 27 Fizzles

Tropical Depression number 27 did not achieve tropical storm status, and thus, the name Gamma. Gamma is the next letter in the Greek alphabet, of which the National Hurricane Center is naming the rest of the storms that form this hurricane season, because the 2006 name list was exhausted.

There are still officially 13 days left in the hurricane season, as it ends November 30, so there's always a chance another named storm will form.

On Wednesday, November 16, the National Oceanic and Atmospheric Administration's National Hurricane Center issued the last advisory on Tropical Depression (TD) 27. At that time, visible satellite imagery showed that the depression had lost its circulation. The remnants were expected to be absorbed into a much larger and developing area of low pressure over the southwestern Caribbean Sea.

Still Watching the Caribbean

On Thursday, at 3:25 p.m. EST, satellite imagery and reports from an air force reserve hurricane hunter aircraft indicate that the large low pressure area near the east coast of Nicaragua has not developed into a tropical depression.

The hurricane hunter aircraft also investigated the remnants of TD 27 to the north of eastern Honduras and did not find a closed surface circulation. However, the plane reported winds of near tropical storm force associated with shower activity in this area.

According to the National Hurricane Center, there is still potential for a tropical depression to form over the western or northwestern Caribbean Sea during the next day or two. Another air force reserve hurricane hunter is scheduled to Investigate the system on Friday, November 18, if necessary.



TRMM Takes Aim at Tropical Depression 27

The Tropical Rainfall Measuring Mission (TRMM) satellite captured these images of Tropical Depression (TD) #27 at 6:37 am EST on 14 November 2005 as the system was entering the eastern Caribbean.

TRMM image of tropical depression 27 on November 14, 2005. Image to left: Image of Tropical Depression 27 from the TRMM satellite taken on November 14, 2005. Click on image to enlarge. Credit: NASA

The first image (left) shows a top-down-view of the rainfall pattern associated with TD #27 as obtained from TRMM's sensors. Rain rates in the center of the swath are from the TRMM Precipitation Radar (PR), the only radar that can measure precipitation from space. Rain rates in the outer swath are from the TRMM Microwave Imager (TMI). The rain rates are overlaid on infrared (IR) data from the TRMM Visible Infrared Scanner (VIRS). TRMM shows the system is still unorganized with no eye and little evidence of curvature in the rain field.




3D TRMM image of tropical depression 27 on November 14, 2005. Image to right: 3D image of Tropical Depression 27 taken by TRMM on November 14, 2005. Click on image to enlarge. Credit: NASA

However, the next image (right), taken at the same time, shows a 3D perspective of the system courtesy of the TRMM PR. The PR reveals areas of deep convection as evidenced by the tall towers (shown in red). When these towers occur near the center of the circulation, it is usually a sign that the system is about to strengthen. However, TD #27 was also encountering westerly wind shear, which was impeding its development. At the time of these images, TD #27 had sustained winds estimated at 30 knots (35 mph) by the National Hurricane Center. TD #27 was moving due west at 9 knots (10 mph) and is expected to slowly intensify.




Twenty-Seventh Tropical Depression Heads Toward Western Caribbean
Expected to Become Tropical Storm Gamma

What was born a tropical depression (TD) on Sunday November 10 at 10 EST, may be named Gamma later today, Monday, November 14 or Tuesday, according to forecasters at the National Oceanic and Atmospheric Administration's National Hurricane Center.

National Hurricane Center's predicted track of Tropical Storm Gamma.Image to right: The National Hurricane Center's predicted track for Tropical Storm Gamma. Click image to enlarge. Credit: NOAA/NHC

Computer model forecasts also call for Gamma to grow into a hurricane as it treks westward through the Caribbean and heads toward the Nicaragua/Honduras border by the weekend.

This 27th tropical depression of the season developed on Sunday over the southeastern Caribbean Sea, about 100 miles (165 km) west of St. Vincent, at latitude 13.5 north, and longitude 62.7 west.

By mid-day today, Monday, November 14, TD 27 continued to organize slowly over the eastern Caribbean Sea bringing heavy rains over parts of the Lesser Antilles.

At 11 a.m. AST (10 a.m. EST), TD 27's center was estimated near latitude 13.8 north, and longitude 63.6 west or about 175 miles (280 km) west of St. Lucia. TD 27 was moving west-northwest near 7 mph (11 km/hr). It had maximum sustained winds of 35 mph with some strengthening expected. Estimated minimum central pressure is 1006 millibars.

Rain to the Islands

TD27 is expected to produce the most rainfall, between 4 and 8 inches, over the Windward Islands. The Leeward Islands, Puerto Rico and the Virgin Islands can expect between 3 and 5 inches of rain. Isolated areas with higher terrain could experience between as much as 10 to 12 inches of rainfall in the Windward, Leeward and Virgin Isles, as well as in Puerto Rico.

Hurricane season ends November 30 in the Atlantic Ocean and Caribbean Sea.

For the latest advisories on tropical cyclones, please visit the National Hurricane Center website at:
http://www.nhc.noaa.gov/

 
 
Rob Gutro
Goddard Space Flight Center