Tuesday, September 14, 2010

Hurricane Igor churning in the Atlantic!

Akshay Deoras,
Severe Weather Forecaster.

Massive Atlantic Hurricane Igor is churning with an intense low central air pressure of 925 mb and Max sustained 155mph winds to the south-west of the Atlantic Subtropical Ride or Bermuda High.
Igor is now a Cat.4 Hurricane and having solid Cloud top temperature!

Already in an environment of low vertical shears and over warm waters and in transition to warmer water in next 12-18hrs, Igor is likely going to strengthen to a Cat.5 Hurricane since the conditions remain very favorable for intensification. Exception to this can be the
recent in process Eye Wall replacement as seen from the Microwave and Water vapour satellite imagery.
Eyewall replacement actually decreases the intensity of the Major hurricane like Igor as there is a change in the symmetry i.e Hurricanes become more asymmetric.
But, Igor do have a golden chance of becoming the first Cat 5 Hurricane of the season in Atlantic.

The dominant Bermuda high will maintain the intensity over next few days as Igor churns in the atlantic. Since a north West move of IGOR must begin soon, Forecasts will concentrate on Bermuda. Igor is following a track away from the eastern Coast of USA and has more threat for Bermuda
But, I don't find Igor dominating Bermuda since a lot of weakening will happen as it encounters cooler SST and dry air on its way. Also, in the upper level forecast till Friday, a blocking jet stream of 70-90kt winds over 40N and 60W i.e SE of Bermuda might have a change
in Igors Northwards Movement. I expect Igor to speed down for some time however I may be wrong since I have seen such a situation for the first time.
See here what I am speaking of

The 200mb NCEP forecast in the atlantic ocean
At intersection of -60 on y axis and 20 on x axis, where in blue color its written 50 is the position where IGOR will be in 42nd hour from now i.e by 18z UTC on Thursday. North of it there is an extending jetstream having a flow towards East.
This situation can likely reduce IGOR's speed or shift Igor towards slight west in the gap of two branch of jets

More details as the situation unfurls.

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