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Tropical Storm Omar on the way; Honduras disturbance growing stronger

By: Dr. Jeff Masters, 1:49 PM GMT on October 14, 2008

Tropical Depression Fifteen is lashing northern Colombia, northern Venezuela, Aruba, Bonaire, and Curacao with heavy rains today, as the storm drifts to the southeast. This morning's 6:35 am EDT QuikSCAT pass saw winds of 45 mph, so this is probably Tropical Storm Omar. An Air Force Hurricane Hunter aircraft will investigate the storm beginning at 2 pm EDT today. Satellite loops show the amount of heavy thunderstorm activity is on the increase, and the cloud pattern is growing more organized. Wind shear has fallen to a moderate 10-15 knots over TD 15, allowing this increased organization to occur. Radar from the Netherlands Antilles shows that the rain has organized into spiral rain bands.

Figure 1. Current satellite image of TD 15.

The track forecast for TD 15
The storm is expected to drift southeastward until an upper-level trough of low pressure swings far enough south tonight to pull the storm northeastward towards Puerto Rico, the Virgin Islands, and the northern Lesser Antilles Islands. Variations in timings between the models have narrowed some, with landfall in the Virgin Islands, northern Lesser Antilles Islands, or eastern Puerto Rico expected sometime between Wednesday afternoon and Wednesday night. Heavy rains should spread into the islands tonight, generating additional rainfall totals of 5-10 inches. The eastern portion of the Dominican Republic will likely get 3-6 inches, and Haiti will escape heavy rains from the storm.

Figure 2. Current radar-estimated rainfall from TD 15.

The intensity forecast for TD 15
Wind shear is expected to remain in the moderate 10-20 knot range over the next two days, and waters will remain warm, 29°C. This should allow TD 15 to intensify into a strong tropical storm with 60-70 mph winds by the time it moves through the Virgin Islands Wednesday evening. The HWRF and GFDL models predict TD 15 will have 65-75 mph sustained winds at landfall Wednesday night.

Links to follow
Puerto Rico radar
Eastern Caribbean buoy 42059
San Juan, Puerto Rico weather

Tropical Depression 16 off the coast of Honduras
Tropical Depression 16, near the Honduras/Nicaragua border, continues to grow more organized. The region is under low wind shear, 5-10 knots. Satellite loops show a large area of heavy thunderstorms that is beginning to take on a spiraling pattern. Heavy rains are affecting extreme northeast Nicaragua and northeastern Honduras.

The forecast for TD 16
Conditions are ripe for TD 16 to intensify into a tropical storm, and a Hurricane Hunter airplane will investigate the storm beginning at 2 pm EDT. The system is expected to track west-northwest today, just off the coast of Honduras. A more west-southwesterly motion may occur tonight and Wednesday, bringing the storm ashore over northern Honduras. Wind shear is forecast to remain low, 5-10 knots, for the rest of the week. As long as the center remains over water more than 50 miles from land and does not stall out, intensification should occur. The system will likely bring 5-10 inches of rain to northern Honduras today through Thursday, potentially causing flash flooding and destructive mudslides. Rain amounts of 2-4 inches are likely today over northeastern Nicaragua and the Cayman Islands. Heavy rains of 4-8 inches will likely affect Belize, northeastern Guatemala, and portions of Mexico's Yucatan Peninsula tonight through Wednesday night. The heaviest rains will stay south of the resort areas of Cancun and Cozumel, though.

It currently appears that the center of TD 16 will stay close enough to the coast that the storm will not grow large and strong enough to tap into the Pacific Ocean as a major source of moisture. However, the counterclockwise flow of air around the storm is already strong enough that it is pulling in air from the Pacific over northern Costa Rica and Nicaragua. This moist flow of air should generate rain amounts of 2-4 inches today along the Pacific coasts of these countries. If 99L were to grow into a strong tropical storm, this moist flow of air would be capable of generating very dangerous rains in the 10-15 inch range along the Pacific coast of Central America.

Links to follow
Puerto Lempira, Honduras weather

Figure 3. Current satellite image of 99L.

Nana and the child of Nana
Tropical Depression Nana has been torn apart by wind shear of 30-40 knots. Regeneration is unlikely due to the continued high wind shear expected along its path. A small area of disturbed weather south-southeast of Nana, near 15N, 41W (90L), has decreased in organization this morning. The circulation of this "child of Nana" is less apparent on this morning's QuikSCAT pass, and the low-level circulation has now been exposed to view, thanks to high wind shear. Nana has pulled her child northward into a region of higher wind shear, and this shear should prevent the 90L from developing any further.

Figure 4. Current satellite image of 90L, the Child of Nana.

Hurricane Ike relief efforts: Monday 10/13/08 update
From StormJunkie's blog today: Portlight.org is currently preparing the next push of supplies to head to the forgotten populations and disabilities community along the Texas Gulf Coast. Due to the exceptional pricing that U-haul has given us on trucks we have found the cheapest way to transport these goods is to continue to utilize our U-haul deal to transport these goods. We will be delivering many items to these outlying communities early to mid next week. Look for updates on this trip as it happens!

Some of the supplies that are being delivered include 50 manual wheel chairs that were specifically requested by the Houston Mayor of Disabilities. We have also received items from Coleman and Dick's Sporting goods which will be on the truck. A pallet of tents has also been donated by an anonymous person. Some quantity of socks has also been donated. As we receive and secure more items we will continue to update. In the mean time, if any have connections that may be able to help us acquire some of the following items; your timely help is greatly appreciated.

Figure 5. Chief Dickie Uzzle of the Bridge City Fire Department opening supplies sent by Portlight. Supplies were not only needed but also greatly appreciated.

Contributions to the portlight.org charity fund are fully tax-deductible, and will go to provide relief supplies for those smaller communities typically bypassed by the traditional relief efforts. More details can be found at StormJunkie's blog.

I'll have an update this afternoon after the Hurricane Hunters have had time to sample today's storms.

Jeff Masters

The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.