Watching Weather Rhythms for Chesapeake-Caribbean Passage

Watching the weather to head from Norfolk, Virginia back to the Caribbean.

We’ve started watching the weather between the East Coast of the US and the Caribbean. What we’re trying to do is get a feel for this years weather “rhythms”. Each morning we send an e-mail to the Marine Prediction Center “server” (for more info on this process, click here) and download the current through 96 hour surface and 500mb synoptic data, along with the wind/wave forecasts. We then look at the satellite image for the N. Atlantic . The final step is to download and study the MPC interpretation notes . (For more info on this, click here).

At this time of year, as the hurricane season is (in theory) tailing off and the equinoctial gales are starting, there are a couple of things to look for. First is the pattern of the surface low pressure systems, and how the upper-level 500mb troughs are rotating through. Each season, and each period within a season, typically has a consistency to how these features go through their life cycle. The only way too get a feel for this is to watch them on a daily basis for two or three weeks before it is time to make the go/no go decision.

We are also watching the pattern of tropical weather, and right now we are not particularly happy with the way this season has gone.

Tropical storms are an efficient system Mother Nature has devised for removing excess solar heat from the tropics and moving it towards the poles. When you have a very quiet year, as this year has been, it means there is a lot of heat left over which has not yet been moved. This increases the chance for a late-season or out-of-season hurricane. We’re not particularly concerned with this when we’re at sea-with the satellite images and the forecast products now available, it is not difficult to pick the right time to go, and/or the avoidance tactics necessary.

But we are a little nervous about a late season blow catching us in the islands.

To keep up with what’s happening on this score, we download the Tropical Prediction Centers fax which shows the surface conditions between Africa and the Eastern Pacific. This is where you see the “tropical waves” coming off the African Coast, and any development of these into closed circulation patterns-which are the precursors to hurricanes.

We take a quick look at these, compare them to the satellite image for the same time period, and then print out a copy. After reviewing the current fax, we then look back through the past week of data. Right now there seem to be quite a few tropical waves for the middle of October-so the odds higher than normal that there will be some tropical storm development over the next few weeks. On the other hand, we’ve got three weeks until the theoretical departure time for the Caribbean 1500-and things could quiet down in the interim.

Posted by Steve Dashew  (October 18, 2001)

Comments are closed.