Dr. Masters co-founded wunderground in 1995. He flew with the NOAA Hurricane Hunters from 1986-1990. Co-blogging with him: Bob Henson, @bhensonweather
By: Dr. Jeff Masters , 9:03 PM GMT on September 30, 2005
The tropical disturbance in the western Caribbean Sea has lost almost all of its deep convection this afternoon, and is not a threat to develop into a tropical depression today. Surface pressures are still falling over this area (see the pressure plot from buoy 42056 about 100 miles southeast of Cancun, Mexico), and the disturbance still has a well-defined surface circulation. However, unless the disturbance can fire up some more deep convection by midnight tonight, it will probably totally fall apart and no longer be a threat to the Gulf Coast.
Wind shear over the system is mostly unchanged at 5 - 10 knots, but a slight bit of extra shear from easterly winds blowing from the Yucatan Peninsula has disrupted the system this afternoon. There is no real change to the forecast--shear is expected to remain the same or decrease as the system moves northwest towards the Yucatan Peninsula or Western Cuba. Given the disturbance's almost total lack of deep convection, Sunday is the earliest I would expect it to be able to develop into a depression. The odds are now 40% at best that this system will develop into a depression at all.
If the system does manage to develop, the Mexican Gulf Coast or Texas look like the most likely targets. The GFDL, which forecasted intensification into a Category 1 hurricane with last night's run, now says the disturbance won't develop at all. Only the Canadian model thinks the disturbance will develop. This model takes the system into the Texas/Mexican border region on Tuesday.
Figure 1. BAMM and GFDL track forecasts.
Hurricane Otis threatening Baja and Arizona
Arizona and Mexico's Baja Peninsula are watching Hurricane Otis, which is strengthening as moves northwest parallel to the Baja Peninsula. Otis is currently a Category 1 hurricane with top winds of 85 mph, but is steadily strengthening, and could attain Category 3 status on Saturday. A wind speed of 46 mph with a gust to 61 mph was reported at Cabo San Lucas on the southern tip of the Baja Peninsula today.
Figure 2. Hurricane Otis.
Otis is taking a path very close to the Baja coast, where a narrow tongue of warm water will enable it to maintain hurricane intensity at a much further north point than most East Pacific hurricanes are able to. A hurricane watch has been issued for much of the Baja Peninsula, and this will be upgraded to a hurricane warning on Saturday. Otis is expected to cross the Baja Peninsula Sunday, and quickly weaken to a tropical storm as it moves up the Gulf of California towards Arizona. By Monday, the remains of Otis should cause 3 - 5 inches of rain to fall over southern Arizona, creating flash flooding problems.
The tropical disturbance about 600 miles west-southwest of the Cape Verde Islands developed an impressive blow-up of thunderstorms near its center of circulation this afternoon. With good spiral banding and upper-level outflow channels beginning to form, NHC decided to upgrade this system to Tropical Depression 19. This depression has a favorable environment to strengthen, and will become Tropical Storm Stan on Saturday, and probably Hurricane Stan early next week. The system is expected to move slowly northwest for the next five days and not threaten any land areas.
Several of the global computer models continue to forecast that a tropical storm may form near the Bahama Islands on Monday or Tuesday. Any system forming in this region would be forced westward or west-southwestward into the Southeast Coast by a strong ridge of high pressure building in. There are no signs yet of any development occurring in the Bahamas, and the chances of a tropical storm forming in this region as forecast are probably around 20%.
Tropical Depression Kenneth dissipated 35 miles east of the Big Island. The remnants of Kenneth will bring heavy rains and the threat of flash flooding to the islands Saturday.
Super Typhoon Langwang, a small but intense typhoon with 140 mph sustained winds, is headed towards China and may hit Taiwan as a Category 3 storm on Sunday. Longwang is expected to gradually weaken but still hit mainland China on Monday as a Category 1 storm.
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