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Tropical Update: September 6th; 5:20p.m EDT
By: MiamiHurricanes09 , 9:15 PM GMT on September 06, 2011
Tropical Depression 14
As of 5p.m EDT the NHC has begun issuing advisories on the tropical wave associated with a well-defined low pressure system in the far eastern Atlantic. Latest satellite images reveal an organizing cyclone with convective banding starting to wrap around the well-defined low pressure system. The cyclone is an environment of favorable upper-level wind shear and surrounded by a moist mid-level atmosphere, and due to this I anticipate gradual intensification over the next few days.
The cyclone is currently cruising towards the west/west-northwest under the zonal flow courtesy of the subtropical ridge. This direction in heading is forecast to persist throughout the next 5 days placing the cyclone near the northern Leeward islands in the aforementioned time frame.
Upper-level winds are not forecast to increase more than 15 knots over the next 5 days and mid-level dry air is also forecast to remain low. Due to this I believe that the NHC forecast intensity is a little too low, and that 14L will reach hurricane status in 72-96 hours rather than 120 hours.
Plus, she's the most beautiful tropical depression I've seen in a long time (lol)...so I'd definitely be keeping a close eye on her if I lived in the northern Leeward Islands, the U.S VI, and the eastern Greater Antilles.
Figure 1. Infrared satellite image of 14L valid 20:49UTC, or 4:49p.m EDT.
Hurricane Katia is starting to meet her demise. The eyewall replacement cycle that has been taking place throughout most of the day appears to be nearing completion, however atmospheric conditions no longer seem to be conducive enough for re-intensification.
The cyclone is moving towards the northwest under the influence of the southwestern periphery of the subtropical ridge. This direction in motion should persist throughout the next 36 hours or so, with a meridional turn thereafter. Beyond 72 hours the cyclone should begin to encounter the mid-latitudinal westerlies, which will induce a northeastward to east-northeastward turn along with a rapid increase in forward speed. I believe that Katia has reached her maximum intensity, however, she will probably maintain her current maximum wind speed value throughout the next 12-24 hours. Beyond 24 hours gradual weakening is anticipated.
The main threat from Katia continues to be dangerous rip currents along Bermuda and the eastern seaboard.
Figure 2. Visible satellite image of Hurricane Katia valid 20:49UTC, or 4:49p.m EDT.
Convective activity over the past few hours in association with 96L has weakened considerably. This really doesn't come as a surprise with the behemoth amount of extremely stable dry air that lies to the northwest of the system. In the 96L's defense, however, an upper-level anticyclone has developed directly atop its vorticity maximum, which is only allowing for 5-10 knots of upper-level winds to impede upon the system.
I still strongly believe that the chances for development over the next 48 hours are low...about 10%. I'll have a more in-depth analysis on 96L tomorrow afternoon so be on the look-out for that.
Figure 3. Visible satellite image of Invest 96L valid 20:58UTC, or 4:58p.m EDT.
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