North America

Wind, swell & tides for North America

The Pacific Ocean

A constant procession of low pressure systems march across the Northern Pacific from October to April. Their exact path is totally dictated by the meandering trajectory of the upper atmosphere jet stream, but they usually make landfall between British Columbia and Northern California. These lows are responsible for sending WSW around to NNW swells to the west coast and even SE swells up in the Gulf of Alaska and chaotic mixes of swell are common. Outside of these months, deep low pressure systems are rare, allowing large high pressure systems to establish themselves offshore.

These highs generate the summer afternoon onshores and weak windswell from the W or NW, depending on how far south you are. This huge seasonal variation is most extreme during July and August, when the Southern Pacific storms are the most likely source of a salvation swell from the S or SW. Smaller storms and frontal activity can also send in SW lines from equatorial latitudes, or else the occasional ‘chubasco’ tropical storm appears off Central America as another unreliable source of summer S swells. Expect winter NW swells to usually be accompanied by S winds and summer S or SW swells to meet prevailing NW winds, dictating which side of the headland or jetty to head to.

Considering Alaska’s latitude, water temps should be colder, but as the Alaska Current splits off the Kuroshio extension, it moderates the whole Gulf of Alaska. The other arm forms the California Current, following the West Coast from BC to Baja, bringing cool water from the Kuroshio back to the equatorial gyres. Coastal upwelling is a feature that keeps the range of water temperatures down throughout the seasons.

Depending on latitude and underwater topography, tidal ranges (heights) vary massively from one region to another. Much of the west coast is in the meso-tidal range, so spring tides oscillate between 7ft (2.3m) and 13ft (4.3m). Many tide-sensitive spots will only work for about one-third of the tide (low, mid or high). The Pacific Northwest experiences macro-tidal ranges of over 14ft (4.6m) on spring tides, resulting in extremely unstable surf conditions, where tide will be the main priority.

North Atlantic Ocean

The jet stream also drags an incessant stream of winter storms across the northern latitudes of the Atlantic, but since these storms are travelling away from North America, the East Coast has to survive on the swells that propagate off the back of the low pressure systems. Many of these storms are spawned in Baffin Bay, between Newfoundland and Greenland and will pump NE swell down the East Coast, especially if they remain stationary, but they are usually quick to spin off toward Europe, taking the swell with them. Cold fronts sweeping across the continent hit the coast and wind up again providing another source of predominantly NE swell. In winter, these frontal systems can take a more southerly path, energised by the warmer waters of the Gulf of Mexico, and usually make oceanfall between Northern Florida and the Carolinas. Alternatively, cold air descending from the Canadian interior will arc down through the Mid Atlantic states, before swinging north again to join up with the established low pressure systems off Newfoundland. These fronts are dubbed Alberta (or Canadian) Clippers, and once again are most likely to send out NE pulses in their wake. Nova Scotia and New England score extra size from proximity to the weather systems, while the Outer Banks and Southern Florida protrude into the deep waters of the Gulf Stream current, which acts as a conveyor belt for the NE swell to head down the coast.

Summer is a feast or famine scenario, with sizeable surf completely reliant on hurricane swells. These most powerful tropical storms are the only low pressure cells that travel towards the East Coast, bringing large swells, but also the threat of widespread damage if they make landfall. Swell direction is dictated by the storm’s track which can waver between due west into either the Caribbean Sea or the Gulf of Mexico or else following an arcing trajectory to the north, where cooler ocean temperatures signal its demise.

Hurricanes can appear anytime between June and November, with September and October providing the strongest possibility of scoring these swells that usually have an element of S to them. Hurricanes aside, summer can be diabolically flat, relying on weak E to SE windchop from the stationary Bermuda High, which dominates the western North Atlantic.

Nova Scotia's Bay of Fundy can experience a depth difference of 50ft (16m) between low and high water, but most East Coast semi-diurnal even tides are low to moderate in the 4-5ft (1.2-1.6m) range.

Gulf of Mexico

Hemmed in by the Yucatan peninsula to the south and Cuba to the southeast, the Gulf Of Mexico must rely on weather systems to actually traverse some part of the expanse of water. Hurricane season runs from June to November, but September and October are most likely to produce a storm that crosses into the Gulf from the Caribbean. This is also the time of year when the winter cold fronts will begin to sweep across the continent on the edge of Pacific low pressure systems.

Strong winds from the SE will build up the swell for Alabama and the Florida Panhandle while Texas will see a more N to E airflow in the winter months. When the fronts pass through the winds will usually veer offshore, heralding the beginning of the end for most Gulf swells, which can disappear in a matter of hours. South-easterly windchop is the most likely source of summer waves, but flat spells can extend for months.

Tidal fluctuations throughout the Gulf are micro (<0.4m), but will still create strong currents at inlets and passes. Every tidal type from diurnal to mixed is represented in this basin.