The winter of 2011-2012 was the warmest on record in Fargo Moorhead. It was nearly 10 degrees above the current 30 year average.
There is no doubt that the overall pattern last winter was a mild one. The upper level wind pattern was consistently from the west allowing mild Pacific air to dominate the season with only a couple of intrusions of Arctic air disrupting that pattern. But another very important element to the warmth was our lack of snow cover. This past week has been a prime example.
Fargo Moorhead missed the big storm earlier this month that left a significant snow cover over central and northern North Dakota. The eight days following the storm the average high in Fargo was 40 degrees, but in usually warmer Bismarck with a snow cover the average high was just 32 degrees. Even Grand Forks with minimum snow from the storm (like Fargo), the nearby snow pack lowered their average to just 33 degrees.
Because the sun angle is so low this time of year making it difficult to melt much snow, an early season snow storm can in turn, influence the average temperature for the entire cold season.
Current snow cover over the area.
Once again I was asked by the State Climatologist in North Dakota to write a summary to what I expect for the upcoming season. What I wrote can be found below. It can also be found in the State Climate Bulletin to be published soon.
Spring and autumns are always the most difficult to forecast because of large swings that can and do occur on both daily and weekly time scales. Plus, with so much cold elsewhere on the planet, this spring in particular has the potential for giant swings from warm to cold. These temperature swings can also lead to prolong periods of dry weather intermixed with brief periods of significant precipitation.
Using that as a backdrop, after a mild March that may end up as one of the warmest on record for the region, April looks to be transitioning to colder weather, followed by a near average May. That would mean, overall, an above average temperature for the season, but we always need to remember, that does not mean consistently above average and a poorly timed cold front can easily hamper the planting season.
Although historically when a La Nina is present is the Pacific, this area has a higher than normal likelihood of recording above average precipitation in the spring, the current La Nina is fading quickly and therefore, the odds favor this season to finish nearer to the long-term average for rain and late season snowfall. If that forecast holds, it would be a welcome change from the excessive spring moisture many areas have recorded in recent years.
The latest spring outlook from the Climate Prediction Center (CPC) for the next three months can be seen below.The CPC is forecasting a slightly higher than normal probability of above average temperatures and equal changes of above, below or normal precipitation. You can find the current and future outlooks, when new ones become available, athttp://www.cpc.ncep.noaa.gov/products/predictions/90day.
Also, the North Dakota State Climate Office has links to the National Weather Service’s local 3-month temperature outlooks for the upcoming year. Those forecasts can be found at:http://www.ndsu.edu/ndsco/outlook/L3MTO.html.
The high snow totals in the mid-1990s and during the past few winters has pushed our normal seasonal snowfall to 50.1 inches. That is the highest average since records have been kept. Because we have recorded several years with above average snowfall in the past 20 years, we sometimes forget that the median snowfall locally is only 39 inches.
The Median is the middle number in a group, meaning that half of the years in our annual snowfall have been less than 39 inches and the other half it was greater than 39 inches. Because snowfall tends to be very memorable to most people, as it either creates great hassles, or it brings great enjoyment playing in it; most of us tend to remember the years with abundant snow more than the years with lesser snow totals.
That brings us to this year as of course there has been little snow so far this season, yet 5 out of the last 6 years have recorded less than one inch of snow in November just like this year and many of those ended up snowy meaning it is far too early to know where this snow season will rank.
Although another tropical system or two could easily form in the coming days and weeks, the hurricane season in the Atlantic Ocean is beginning to wind down. If you ask most Americans if it was a busy or quiet season, for the 3rd straight year, most people would say it was a quiet year. Only one hurricane, Irene struck the coast of the United States this year. That was the first land falling hurricane in nearly three years ending the longest such stretch since the Civil War.
Another positive factor of the season so far is that no major hurricane (Category 3 or higher) made landfall in the country. The last time that occurred was Hurricane Wilma back in 2005. It is these reasons that this hurricane season will likely be remembered as a quiet one, although, by the numbers, 17 storms formed, which is above average. But with tropical systems it is where they go, rather than the actual number that is far more important.
As we move forward into the second half of April, the weather will continue to be a big player not only with continued flooding concerns, but also for the spring planting season. Currently the Northern Hemisphere has well above average snow cover with much of Canada still white. Until that snow cover diminishes to our north the tendency will be for our area to remain cooler than average as our dominate flow this time of year is still out of Canada.
Springs following a La Nina tend to produce a ridge of high pressure over Florida. That has been the case in recent weeks allowing the waters in the Gulf of Mexico to warm up above seasonal normals. That warmer water adds potential additional moisture to storms moving across the United States, plus adds to the thermal contrast across the country.
What all of these ingredients will do is increase the risk of cooler than average temperatures and above average precipitation for this area over the next few weeks.