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EAST COAST LA NINA
Atlantic Surf + Weather Outlook for Fall/Winter 2010-2011
By:
Mike Watson
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With the end of hurricane season in sight,
we continue to monitor La Niña in the eastern Pacific. The El Niño/La Niña phenomenon influences the weather globally, and an increasingly stronger La Niña will continue to influence the East Coast weather as we head into fall/winter.
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Ok -- so what is La Niña? La Niña is the counterpart to the more famous and well known El Niño. Both of these combined make up what is called the El Niño-Southern Oscillation or ENSO. While El Niño is known for warmer than normal waters over the eastern Pacific, La Niña is the exact opposite which means we are seeing cooler than normal water over the eastern Pacific. This is why you may see El Niño called the 'warm phase' of ENSO and La Niña called the 'cold phase' of ENSO. As we head into winter the tropics will shut down as we begin to look more at our winter lows as our predominant source of surf. But unlike an El Niño winter, research indicates that La Niña results in a storm track more westward and inland towards the Great Lakes region rather than over the East Coast. Also storm tracks during La Niña are shifted more poleward or northerly (Climatology and ENSO-Related Variability of North American Extratropical Cyclone Activity Timothy Eichler, Wayne Higgins Journal of Climate 2006 19:10, 2076-2093). Further, is has been found that the eastern US sees less frequent winter storms from December through February during the La Niña winter (An East Coast Winter Storm Climatology Matthew E. Hirsch, Arthur T. DeGaetano, Stephen J. Colucci Journal of Climate 2001 14:5, 882-899). Does this mean less surf for the East Coast? Certainly not, but it may be a fairly poor winter for many Gulf coastal states due to the more northerly track of these systems. This will result in cold fronts not reaching as far south, setting up weaker pre frontal S windswell for the Panhandle and weaker post frontal NW windswell for West Florida. Also, weaker fronts mean less chance for significant pre frontal SE windswell events for the Texas coast with a weaker post frontal NE windswell there. However Texas may benefit from a persistent western Atlantic ridge that extends into the Gulf yielding at least some rideable ESE windwell/swell. The Northeast will see the typical prefrontal S swells, but many of these may turn out to be the more 'one and done' varieties due to the more northerly track of the fall/winter storms effectively shortening the southerly fetches associated with these systems. ...it would not be surprising to see a few lows push into the Atlantic through the fall/winter and send the East Coast some swell - not unlike the current low pressure system which is set to send a healthy swell to the southern latitudes.
The Northeast will occasionally still see the healthy south swell set up just like this past solid SSE swell event but these will be a bit less frequent than average. N becoming NE winds will blow over the Mid Atlantic as high pressure fills in behind these passing fronts but will shut off rather quickly as the ridge quickly flattens out and pushes over the western Atlantic. This will keep the Mid Atlantic and SE regions seeing many days of frustrating marginal windswell events. Florida is likely to see steady NE rotating E windswell events from this ridging although these are not expected to be very big or significant. However it would not be surprising to see a few lows push into the Atlantic through the fall/winter and send the East Coast some swell - not unlike the current low pressure system which is all set to send a healthy, powerful swell to the southern latitudes. The Caribbean is likely to see more NE swells than normal but less NW swell. Why? While storm tracks are more inland over the United States effectively resulting in less frequent NW swells, the eastern side of Atlantic has an active storm track during La Niña - perfect for sending long period NE swells to the Caribbean. Weather wise Florida will be drier and warmer than normal, and this is very much welcome after last year's freezing weather. The warmer than average temperatures are expected to generally extend northward into the Mid Atlantic region thus many locations along the Eastern Seaboard can expect a rather mild fall/winter especially compared to last year. The Northeast is generally expected to see average winter temperatures. So while the East Coast will locally have moments of good surf, expect several periods of down time as the storms periodically take a break and/or track further inland away from the coast. MORE FORECAST SURFLINE HOME PAGE |