WunderBlog Archive » Category 6™
Category 6 has moved! See the latest from Dr. Jeff Masters and Bob Henson here.The cold water wake of Dean
A westward-moving tropical wave is kicking up some disorganized thunderstorm activity in the southern Caribbean, between Colombia and Jamaica. This area has a circulation at middle levels of the atmosphere, but no circulation at the surface, as seen in the 7:21am EDT QuikSCAT pass. The wave is under 10-20 knots of wind shear, and could undergo some slow development. None of the reliable models are predicting that this system will develop into a tropical depression, but it could bring heavy rains to Nicaragua and Honduras on Tuesday and Wednesday.
Of the four reliable forecast models for forecasting the genesis of tropical cyclones, only one--the UKMET--is now calling for formation of a tropical depression late this week off the coast of Africa. There are some active tropical waves that will start pushing off the African coast later this week, and we'll have to watch this region for development.
Heavy thunderstorm activity off the Virginia coast is associated with an old frontal boundary. A non-tropical area of low pressure is forming here and is expected to move off to the northeast. This low could become tropical if the shear relaxes from its current 20-30 knots.
First snow of the season
Fall is fast approaching, as evidenced by the first snow of the season in the Colorado Rockies. Snow fell Friday on mountain peaks above 12,000 feet. Late August snow is not unusual for the Rockies. Ski season is still 70 days away, though!
Figure 1. Sea Surface Temperature (SST) departure from normal for Sunday, August 26, 2007. Image credit: U.S. Navy.
Hurricane Dean's wake
Hurricane Dean's passage will be remembered not only by the people it affected, but by the ocean itself. A large, powerful storm like Dean generates a tremendous amount of mixing of the ocean, which brings up deep, cold water to the surface. Dean's passage cooled off the Gulf of Mexico waters near the Yucatan Peninsula by up to 3 degrees C (5.6 degrees F). The western Caribbean was not as strongly affected, since there is a much deeper layer of warm water there, thanks to the presence of the warm Loop Current. The cold water anomaly left by Dean will take several weeks to dissipate.
I'll have an update on Tuesday.
Jeff Masters
Of the four reliable forecast models for forecasting the genesis of tropical cyclones, only one--the UKMET--is now calling for formation of a tropical depression late this week off the coast of Africa. There are some active tropical waves that will start pushing off the African coast later this week, and we'll have to watch this region for development.
Heavy thunderstorm activity off the Virginia coast is associated with an old frontal boundary. A non-tropical area of low pressure is forming here and is expected to move off to the northeast. This low could become tropical if the shear relaxes from its current 20-30 knots.
First snow of the season
Fall is fast approaching, as evidenced by the first snow of the season in the Colorado Rockies. Snow fell Friday on mountain peaks above 12,000 feet. Late August snow is not unusual for the Rockies. Ski season is still 70 days away, though!
Figure 1. Sea Surface Temperature (SST) departure from normal for Sunday, August 26, 2007. Image credit: U.S. Navy.
Hurricane Dean's wake
Hurricane Dean's passage will be remembered not only by the people it affected, but by the ocean itself. A large, powerful storm like Dean generates a tremendous amount of mixing of the ocean, which brings up deep, cold water to the surface. Dean's passage cooled off the Gulf of Mexico waters near the Yucatan Peninsula by up to 3 degrees C (5.6 degrees F). The western Caribbean was not as strongly affected, since there is a much deeper layer of warm water there, thanks to the presence of the warm Loop Current. The cold water anomaly left by Dean will take several weeks to dissipate.
I'll have an update on Tuesday.
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.