COOS BAY — A major winter storm is headed this way on Sunday and Monday — and will bring with it 30-plus-foot seas at the same time commercial crabbers just set their gear and made a first haul.

It’s no Pineapple Express, the kind that brings warm southerly winds after gathering energy in the tropics.

It’s no pure Arctic blow coming down from the north, either.

This storm could be considered more like a combination of the two.

Two National Weather Service computer models showed a low-pressure system developing about 1,000 miles offshore on Wednesday that could bring storm-force winds of more than 55 mph and 32-foot combined seas to the coast on Sunday and Monday, said NWS spokesman Ryan Sandler.

Usually, a storm prediction of that magnitude more than five days out still has some uncertainty attached to it, but this one seems especially strong for at least two reasons: computer model agreement and its low — really low — pressure.

Sandler said one computer model showed the system measuring 946 millibars of atmospheric pressure and another model showed it at 949 millibars.

“That is extremely unusual,” Sandler said, noting that it likely will track north and cross Canada.

High-pressure systems that bring fair weather usually measure about 1,000 millibars. And, for comparison, the Columbus Day storm in 1962 had a low pressure of about 960 millibars. The Columbus Day storm track took it right up the West Coast, offshore, but the associated fronts with it wreaked havoc on the coast and in the Willamette Valley.

It was in February 1999 that storms with 25-foot-plus waves pounded the New Carissa to its current site on the North Spit.

Similar fronts with the developing system likely will bring significant wind and waves to nearshore waters beginning late Saturday and lasting through Monday.

The computer models differ on the speed and specific track of the storm, Sandler said late Wednesday, but its expected impact at a time when the West Coast crab fleet will be at sea has forecasters on alert.

By 6:30 p.m. on Wednesday, the NWS posted a special weather statement to its Web site.

“An unusually strong high wind and seas event is forecast to develop along the Oregon Coast Sunday and Monday. This storm will coincide with the early days of crab season, posing a significant and dangerous impact to mariners,” it said.

Because the system is developing so far offshore, it likely will have an occluded front — so the air won’t be that cold, but it won’t be that warm, either, Sandler said.

Before the ocean swells hit, southerly winds will pick up and continue through the weekend.

But eventually, there is the potential for a large northwest swell combined with southwest winds over some of the ocean waters.

“That’s ugly,” Sandler said.

Regardless, this is one storm that residents and fishermen should pay attention to.

“Gusts of 60 to 80 mph along the coast are possible with even higher gusts along the coastal headlands,” the NWS statement says. “Dangerous seas of 25 to 35 feet are forecast to develop.

“Details are not certain this early, but confidence is high that a significant event will occur. Mariners and residents along the south Oregon Coast are advised to stay informed of this developing storm.”

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