Federal emergency managers and weather forecasters urged the nation Friday to prepare for extreme weather this fall and winter, as El Nino's signature warm Pacific waters fueled Hurricane Patricia into the strongest storm on record to threaten North America.
But while the global climate pattern poses flooding risks from drought-parched California to the Gulf Coast, in Maryland, a different hazard looms — heavy snow.
As an intensifying El Nino demonstrates its strength, meteorologists say the moisture it sends streaming across the southern United States could deliver some winter wallops. Though El Nino winters can be otherwise mild and unremarkable, they have produced some of Baltimore's most memorable snowstorms.
"A lot of times, if you get one big storm, it's what people tend to remember for the whole winter," said Dan Hofmann, a meteorologist at the National Weather Service's Baltimore/Washington forecast office. "Usually those big humdinger-type storms happen during El Nino winters."
The climate pattern is marked by unusually warm waters along the equator in the Pacific Ocean, blown east from Australia, Papua New Guinea and Indonesia. Massive storm clouds rise from the warm seas, sending heavy precipitation eastward across northern tiers of South America and the southern United States, while causing droughts and wildfires in parts of Southeast Asia and Oceania.
This El Nino appears likely to be among the strongest in a generation, rivaling the winters of 1982-1983 and 1997-1998.
It already has contributed to the rapid intensification of Hurricane Patricia, which grew from a tropical storm to the strongest hurricane the National Hurricane Center has ever recorded in a period of about 30 hours.
"This is undoubtedly an El Nino-fueled hurricane," said Bill Patzert, a climatologist at NASA's Jet Propulsion Laboratory in Southern California.
With a wet winter looming, Federal Emergency Management Agency officials are urging residents of California and the Gulf Coast to buy flood insurance and begin preparing for disaster during the season ahead. In the West, parched and wildfire-scorched land won't be able to absorb expected rainfall, likely causing flooding and mudslides, FEMA spokesman Rafael Lemaitre said Friday.
Earlier this month, heavy rains sent walls of mud flooding onto highways north of Los Angeles, trapping vehicles and drivers.
"If there ever was a time to buy flood insurance, this is that time," Lemaitre said on a conference call with reporters Friday.
The enhanced chance of precipitation is forecast to extend all the way to the East Coast. The National Oceanic and Atmospheric Administration's winter forecast released last week estimates a 30 percent to 40 percent chance of above-normal precipitation across Maryland and up into New England.
The stream of moisture from the Pacific flowing across the southern third of the country ensures one key element of a snowy winter.
But the other — cold air — can be a matter of luck during El Nino winters.
In 1997, meteorologists warned Marylanders of a brutal winter, with double the normal risk of a major snowstorm. But only 3 inches fell.
Fifteen years earlier, a single storm made the otherwise unremarkable winter of 1982-1983 memorable. One of the mildest Decembers in a generation and less than half of normal snowfall preceded a February blizzard that dumped nearly 2 feet of snow, paralyzing Baltimore in what was then the second-worst snowstorm in the city's history.
While El Nino's strength can often keep the cold bottled up in the Arctic, forecasters said they see some signs suggesting it will, at times, dip southward, as it has during the past two frigid winters.
"We're not thinking this is going to be one of those warm, snowless El Nino winters," said Bob Smerbeck, a senior meteorologist with AccuWeather.com.
For example, warm water in the northern Pacific suggests the jet stream may end up dipping south across the United States, sending cold air into the Great Lakes and Northeast, said Joe Bastardi, chief forecaster for WeatherBELL Analytics, a meteorology consulting firm.
Smerbeck agreed, predicting a mild start to winter and then a potentially snowy end once polar air comes spilling across the eastern part of the country.
"It might come in one or two storms," he said. "The whole winter may be kind of a dud, but you can pick up a decent snowstorm."
The potential, at least, for major snowstorms is high, Hofmann said. "What El Nino does more times than not is it increases the moisture in storminess," he said.
That was true in 2009-2010, when a moderate El Nino helped bring back-to-back February snowstorms that together dumped about 45 inches of snow on Baltimore. Though El Nino is known for mild Decembers, a storm dropped 18 inches of snow in December 2009, for a record seasonal total of 77 inches.
Other memorable El Nino-induced storms in Baltimore, besides 2010's "Snowmageddon" and the February 1983 blizzard, include the Palm Sunday storm of March 1942 and the blizzard of February 2003.
While other parts of the country get their biggest snows from lake effects or elevation, in Maryland, the strongest storms are a product of moisture-laden systems from the south meeting cold air blowing in from the north. In many cases, high-pressure systems over the northern Atlantic block storms from moving out to sea, instead sending them slowly up the coast.
There are also winters where El Nino's warmth dominates. The winters of 1997-1998, 1991-1992 and 1972-1973 all have two things in common: the presence of El Nino and a place high on the list of Baltimore's least-snowy winters.
"A lot of times a strong El Nino can overwhelm a lot of other signals," Hofmann said.
Still, nearly snowless winters are anomalies when it comes to El Nino and Baltimore. In an average winter, about 20 inches of snow falls at Baltimore-Washington International Thurgood Marshall Airport, but in El Nino winters, that average jumps to about 27 inches.
While there aren't any freezing temperatures in the immediate forecast, snow season has technically begun in Baltimore — the earliest measurable snowfall on record came Oct. 10. By November, at least a trace of snow has been recorded on every date.
Tribune Newspapers contributed to this article.