Using Medium Range Computer Models for Guidance

By WeatherFlow meteorologist Shea Gibson

Check out the GFS (American model) short to medium range forecast for the North Atlantic Ocean out to 384 hours (16 days). Notice the “H” bouncing around out there. This is the Bermuda-Azores High that waxes and wanes back and forth almost all summer long (and much the year). This is known as a “blocking pattern” and provides Easterly trade winds through the Windwards, Antilles, Caribbean islands, Bahamas and the Keys. For us locally along the Southeast/East Coast, when it builds further west and we get a stronger Bermuda High presence, we generally see stronger Southerly winds help to build our afternoon Sea Breezes. Conversely, the further east it fades, the weaker those Southerly winds and associated Sea Breezes become. It also is a steering mechanism for tropical waves and tropical cyclones. But also notice that there are no areas of concern right now, for the short or medium term forecast.

Typically beyond 3-5 days, these models become very erroneous (with the exception of the EURO at times to a certain extent), but ok to watch for a few guidances. Even with all of the super computing we have in today’s technology, the actual “skill” is only around 6 days, but barely that. Just remember when looking at them, and even in our WeatherFlow products, that they are just a numerical/computer forecast opinion of what the winds and weather will do.

This GFS .gif loop is courtesy of Tropical Tidbits / www.tropicaltidbits.com

Cheers and stay safe

Shea Gibson
WeatherFlow Meteorologist/Wind Forecaster
Outreach & New Station Projects
SE Region/East Coast
Twitter: @WeatherFlowCHAS

Posted in Cape Cod, Chesapeake Bay, Coastal Georgia, Coastal South Carolina, Delmarva, Long Island/SE New York, Long Island/SE NY, Massachusetts North Coast, New Jersey, Outer Banks of North Carolina, Rhode Island, SouthEastern North Carolina, Tidewater Virginia