NICycloneChaser's WunderBlog

Tropical Storm Tomas

By: NICycloneChaser, 10:04 PM GMT on November 02, 2010

Good evening!

So, the Hurricane Hunters were back in Tomas again this afternoon, and they found that, contrary to the forecast, Tomas had in fact weakened further, now with max sustained winds of 40mph. The aircraft found an elongated circulation, probably a result of dry air intrusion and moderate/strong wind shear. However, Tomas has been firing up a lot of convection around himself throughout the day, and is a large storm. Wind shear is forecast to continue to relax for the next few days, and the atmosphere in the Carribean seems to be moistening, so intensification back to hurricane strength is still being forecast before Tomas makes contact with land (I'll come to this in a minute!). Due to Tomas' large size and elongated circulation, there is a fair amount of organisation to be done before any quick or rapid intensification can take place, however he still has another 3 or so days over water to get himself sorted, and rapid intensification is a possibility before land contact. At this time, it seems likely that Tomas will be a high end Cat 1/ low end Cat 2 by the time it reaches the islands to its North, but major status is still atainable.

Now, onto track. In the last few model runs, the consensus has shifted to the west, and although landfall (or at least contact with land) appears likely around Jamaica, Cuba, or Haiti, there remains a fair amount of disagreement in the models. The UKMET and NGFDL show Tomas coming close to, if not over, Jamaica, before making landfall somewhere in eastern Cuba. The HWRF and GFS show a sharper bend, with Tomas avoiding Jamaica and moving over Haiti before continuing off into the Atlantic. The GFDL, and to an extent the NOGAPS, show the worst-case scenario for Haiti, with the trough not fully kicking Tomas back into the Atlantic, leaving Tomas in an area of weak steering currents to roam the waters just north of Haiti. This could allow Tomas to mantain intensity (wind shear dependant), and could mean a serious amount of rainfall for Haiti.

In the longer term, it seems increasingly likely that the trough currently moving down to the east coast of the US will lift out before fully recurving the storm, leaving it to roam somewhere north of the Carribean. The UKMET and NGFDL show Tomas moving through the Bahamas, before continuing to move NE/N, while the GFDL and NOGAPS leave Tomas wandering about north of Haiti. It is difficultn to know where exactly Tomas will head should the trough leave him behind, or what his intensity could be like. However, the Gulf jet stream would likely cause serious wind shear should the storm follow the path of the UKMET or NGFDL. It seems unlikely at this time that Tomas will at any stage threaten the US, although it is something worth keeping an eye on.

My thoughts are with the residents of Jamaica, Cuba and Haiti as they prepare for this storm.


The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.

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