Atlantic Weather Patterns for Spring 2010

Apr 22nd 10
By David Cannon, Weather Routing Inc.

It's spring in the Northern Hemisphere and, with the change in season, it’s time for many mariners to think about making the long trek across the Atlantic into the Mediterranean for the summer. Will it be fair winds and smooth seas, or does Mother Nature have other plans?

This past winter has been fairly active as one well-known weather phenomenon has played a part over the past few months: El Nino. El Nino episodes affect weather patterns on a global scale, including the North Atlantic. During El Nino, the southern branch of the jet stream (or the subtropical jet stream, which develops during late autumn and early winter as the upper atmosphere develops a split flow) becomes more active, as more frequent and stronger lows and gales race eastward from the subtropical Pacific across the southern United States and onward into the Western Atlantic. Frequent bouts of adverse weather cover much of the western tropical and subtropical Atlantic as these lows pass off to the north.

Indications are that the moderate to strong El Nino, now in place, will continue through April, before diminishing and weakening during May. With this in mind, we will likely see fewer intensifying lows and gales, as El Nino weakens and as the aforementioned split flow and subtropical jet stream become less prevalent. Also, the large high pressure ridges that are commonplace during winter will weaken and become less frequent during spring, meaning less frequent and less severe bouts of enhanced trade winds and larger head seas for those traveling east, especially later in the spring (May).

In short, it seems spring in the North Atlantic will remain active, gradually giving way to conditions more typical of mid-spring as El Nino weakens during May. It is unlikely that significant route deviations to avoid large seas from frequent large gales and storms will be needed, but more feasible for those heading east from the Caribbean to utilize routes that minimizes head conditions, while avoiding the risk of dangerous, large seas from lows and gales to the north. You will need to watch the “cut-off” lows and gales that are typically found in mid-ocean (south of 30N) during April, though with ample warning, it’s often feasible for vessels to alter course and pass south of these systems, thereby minimizing the head conditions found farther north.

Always be informed of the weather you can expect along the way and stay safe. Keep a weather eye open.

David Cannon is a Yacht Operations Manager and Senior Meteorologist at Weather Routing Incorporated, which has provided weather forecasts and consultation to mariners since 1961. Contact Weather Routing Inc. at 1-518-798-1110; wri@wriwx.com; www.wriwx.com; www.seaweather.net

 

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Tags: Essentials Weather 



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1 Comments
  • It can be challenging When you first start using Pro weather routers and they communicate abbreviated Meteo observations to you over the Sat C in meteorological lingo like "hold latitude, Stacked Low" or "pinch off forming in westerlies ", " Cutoff Low drifting south ", " expected multipolar 0900 " Bubble high forming" Hmmmm ?? A good way to get a handle on the lingo and prepare for a Pro routed crossing is http://www.stormtrack.org/forum/index.php

    Oh and Dave if Your going to submit another blog maybe go over the strategy for sailing thru Oceanic clouds....rising convection vs falling rain clouds. Much useful distance to be made working the clouds on a crossing ..
    Posted by junior_1 23/04/2010 10:43:25

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