The very warm and wet start to winter comes courtesy of El Niño, ranked among the strongest in modern times.  This powerhouse El Niño should continue to exert its influence through the final two-thirds of winter, but we should see some temporary breaks in the pattern with some colder periods. The dominance of El Niño is a sharp departure from the feedback mechanism that dominated our prior two winters: The big, bad blob in the northeast Pacific!

Epitaph

Earlier this month, meteorologist blogger Cliff Mass announced the death of the “blob” in the northeast Pacific Ocean.

The “blob” refers to the large area of very warm waters that helped set up a bulging area of high pressure over Alaska, around which the jet stream flowed, directing impressive cold over the U.S. for the past two winters and blocking storms from hitting the West Coast.

While some had speculated that the “blob” could throw a wrench into this winter’s super El Niño forecast, most meteorologists (including Mass) expected the El Niño to win the battle to influence North America this winter. And wow has it been winning! CWG’s Angela Fritz showed this quite clearly in last week’s blog detailing the West’s winter walloping.

Water temperatures are still marginally warmer than normal in the Gulf of Alaska area, indicative of a positive Pacific Decadal Oscillation, but they are nowhere near the super-warm anomalies we saw last summer or in the prior two winters:


Sea surface temperature difference from average show only weak positive departure where the blob once dominated in the northeast Pacific. Much warmer than normal sea surface temperatures are seen in the tropical Pacific, reflecting El Nino conditions.

Sea surface temperature in the northeast Pacific, once home of the warm ‘blob’, have cooled dramatically over the past six months.

El Niño and balance of winter

So what does the death of the blob mean for our remaining two months of meteorological winter?

As of this writing, a massive El Niño continues to dominate the Tropical Pacific Ocean with recent November to December readings outpacing the prior strongest event in the modern day record, 1997-98. The current outlook is for this Godzilla-sized event to stay quite strong into the early spring. That means the old rule of thumb for a strong El Niño in the Mid-Atlantic probably still applies most of the time: warm and wet (more on this, below).

Just two weeks ago, the IRI group issued their latest compilation of global model forecasts for the future of El Niño. I show their chart here, but I mark it up to show the typical strong and super categories so you can see how much longer we have to go before it goes away:


Model forecasts of El Nino showing it holding at super or at least strong levels through winter, before rapidly weakening. (IRI)

Lookout West and South

January to February of strong to super El Niño usually finds the Pacific “firehose” jet stream shifting southward to point toward Southern California and then across the Deep South. This means that especially February is poised to see very heavy California precipitation with mudslides likely being a big news topic on that side of the winter.

Here are the precipitation anomalies for January and February from our strong to super El Niño predecessor, 1998:


Maps show precipitation was much above normal in the West and Southeast during the last big El Nino event in 1998.

A cool and wet-dominated pattern should really work to erode California’s massive drought over the coming months with lingering wetness expected into the spring also.

What about the East Coast?

The “warm and wet” mantra is favored to be the main story for us based on powerful El Niño forcing and the inability to establish durable, cold, blocking influences to change that narrative.

In January through March 1998, Washington, D.C. reported a trace of snow each month. There was enough variability for some occasional snow chances (and we seem to be setting up for a colder, variable period in the first half of January), but the big storms were typically too warm to generate big snowfalls for us. The prior big El Niño from 1982-83 opened up a brief window in middle February to deliver a massive snowstorm with the monthly total in Washington, D.C. being a hefty 21 inches.

This El Niño event is stronger than the 1983 episode, so the thinking is that warmer Pacific influences could stay stronger longer- as we have seen so far this winter- to prevent significant snow opportunities. Nonetheless, while still warm, January to February ahead are not expected to be as super-warm as December thanks to the gradually weakening El Niño event and some other factors.

The bottom line is that we need to remain diligent, but the background strong to super El Niño state suggests the need to also be reasonably skeptical of bigger cold and snow threats as more often than not, they’ll just be false alarms.  Big El Niño episodes give us big moisture, but the cold air connection is the challenge.