A few weeks ago the National Weather Service was optimistic that the upcoming North Dakota winter would be a warm one. The reason? El Nino had formed as expected, meaning warm ocean temperatures would result in another mild winter for North Dakota.
Uh-oh. El Nino's existence has changed so much recently that previous predictions of a very tolerable winter have now been canceled. El Nino had formed, and was expected to build, but lately the hoped for warm influence has lost its momentum.
"El Nino is trending more toward neutral. It has gradually gone down, down, down," said Michael Mathews, National Weather Service hydro-meteorological technician, Bismarck. "We're still thinking above normal temperatures for this winter, but we're not thinking anything outrageous."
With predictions of much higher than normal temperatures no longer considered a possibility, there's still a chance of fairly agreeable temperatures during the winter ahead. How much warmer? Well, not a lot.
"We still think we'll see the average temp above normal, maybe more warm days than normal," explained Mathews.
While that doesn't sound so bad, warmer than normal in NWS terms would be a single degree or less. According to Mathews, some upcoming winter days could be five or 10 degrees above normal or just one.
Now, with El Nino virtually out of a role this winter, meteorologists turn their attention to Arctic oscillation. In short, Arctic oscillation is a comparison of pressure north of the Arctic Circle compared to the pressure in the mid-latitudes.
"Arctic oscillation plays a big role in our winter weather," said Mathews. "But it is something we can't look at three months into the future, usually only about two weeks. It is really more for cold air outbreaks, not so much for precipitation."
The change in the status of El Nino is reflected in the latest long-term outlooks issued by the Climate Prediction Center. Previous forecasts called for above normal chances for above normal temperatures for all of North Dakota through February. The latest outlook now calls for normal temperatures in November and a chance of above normal temperatures for parts of western North Dakota in December and January. The forecast for precipitation is rated as normal through the same period.
While excess snowfall would bring its own problems to the state, it might be exactly what is needed. According to the NWS the state is in need of replenishment of deep soil moisture, without which drought "impacts in 2013 could be significantly greater than those felt in 2012."
"It would be a very bad start to the year without moisture," said Mathews. "It is never good to start dry."
The NWS has also announced a change in how winter weather will be forecast in the coming months. Actually, it is a return to more familiar previous forecasting procedures. The NWS in North Dakota, South Dakota and Minnesota experimented last winter with the issuance of "extreme cold" watches and warnings rather than more traditional wind chills.
"It was a regional decision, basically. We just decided to drop it," said Mathews.
As a result, forecasters will return to the use of wind chill watches, warnings and advisories for the upcoming winter. Wind chill advisories will be issued for wind chills of minus 25 to minus 39 degrees and winds of 5 miles per hour or greater. Wind chill warnings will be issued for wind chills of minus 40 degrees or colder with winds of 5 mph or greater.