Tuesday, October 19, 2010

All Eyes Fixed on Another Weather Disturbance

    Heavy thunderstorm activity has increased and grown more organized over the past day over the southwestern Caribbean between Honduras and the Cayman Islands in association with a tropical disturbance. A surface circulation may be beginning to form, and the Hurricane Hunters are scheduled to investigate the area this afternoon to see if a tropical depression is forming. The storm is currently moving north-northwest at 5 - 10 mph, but is expected to move west or southwest beginning on Wednesday, making the storm primarily a threat to Honduras, Mexico's Yucatan Peninsula, and Belize late this week.
    Recent satellite imagery shows that 99L has some rotation, and the winds on the northeast coast of Honduras at Puerto Lempira have shifted to the west-northwest, implying that 99L may be developing a surface circulation.
    Water vapor satellite loops reveal that the atmosphere in the Western Caribbean is moist enough to support development, and the waters beneath are plenty warm, at 29°C. The current north-northwest motion of 99L should continue until Wednesday, when a strong ridge of high pressure is forecast to build in, forcing 99L to the south or west. However, steering currents will be weak Wednesday through Friday, making it difficult to predict where 99L may wander to.
    The only models that develop 99L are the GFDL and HWRF. The GFDL model predicts that 99L will spend enough time over water to develop into a hurricane, and brings the storm to the coast of Mexico's Yucatan Peninsula on Sunday morning. The HWRF model has 99L making landfall over Honduras late this week, before the storm has a chance to develop into a hurricane. NHC is giving 99L a 40% chance of developing into a tropical depression by Thursday. I believe the odds are higher, near 60%. The Hurricane Hunters are on call to investigate 99L this afternoon. (from Dr. Jeff Masters' WunderBlog: Weather Underground)

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