Invest 94 in the Caribbean

June 3, 2011

To learn what invests are and how they are numbered, read my post “Notes on tropical weather invests“.

This afternoon the National Hurricane Center designated an area of low pressure in the Caribbean as Invest 94 and the most recent Tropical Weather Outlook gives it a 20% chance of becoming a tropical cyclone in the next 48 hours.  The genesis of this low was fairly well anticipated; its development less so as models at various points in the last week made it into more than what it has become thus far. For example, the Canadian model on Thursday night of last week was showing a tropical storm forming by yesterday evening (from Dr. Hart’s tropical cyclone model page).

The past isn't what it used to be

When I wrote on Wednesday night that this area of low pressure, then off the coast of Nicaragua “will be tagged as Invest 94 in the next day or so”, the global  models were not in unanimous agreement on how it would develop into a storm, but they were in decent agreement that it would do so.  That consensus fell apart on the next set of model runs and has not been restored.  At the moment, the Navy’s NOGAPS model is the only global model showing this becoming a tropical cyclone.  Even though the model has had its fits and starts with this system as well and it has had a history of spuriously spinning up storms in the southwest Caribbean, its idea of the low becoming a tropical cyclone of its is  plausible.  The area with conditions favorable for tropical cyclone formation is fairly tiny (a subtropical jet just to the north makes for extremely inhospitable conditions there), the spot where it is at right now is “just right”.  Right now the short-term forecast for a drifting motion with continued rain in Jamica and Hispanola seems to be the only sound one.

The  image below is from the NHC’s tropical cyclone climatology page and shows where tropical cyclones have formed in the June 1-10 time-frame in the past.  Climatologically speaking, the northwest Carribean is the place for developing storms this time of year in the Atlantic basin.

Land-lubbers, for now



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