October 2008 through March 2009 was the wettest such period on record with 13.13 inches of rain and melted snow measured officially in Fargo Moorhead. This surpassed the previous record for that period set back in 1982-1983 when 11.27 inches fell. That same period in 1996-1997 brought 10.70 inches of liquid equivalency which ranks that cold season third all-time.
Even previous to our cold season, this area had very wet summer and autumn seasons in 2008. So you may ask “will this wet weather continue?” April, although often cloudy and cool did finish well below average for rainfall and historically a high percentage of winters that had abundant precipitation during the October through March stretch ended up with close to average summer precipitation. Every year is unique and May could finish wet, but the odds favor as we move into summer the extremely wet weather will gradually wane.
Last Thursday, April 23, Fargo Moorhead recorded the first 70 degree day of the season. The long term average for the first 70 is on April 18, so even with the persistently cold weather this spring; we did manage to hit that milestone around the normal date.
But not only did we record our first 70 of the season last week, but also our first 80, as the official high on Thursday was 82 degrees. The average first 80 degree day of the season is on May 5, therefore earlier then the seasonal average. You may ask yourself, “how unusual is it to hit 80 without a previous day in the 70s”? 2009 was only the 11th time since 1881 that the first 70 degree day of the season happened to be a temperature of 80 degrees or higher. The last such occurrence was back in 1996 with a high of 83 degrees on May 15.
This week has been designated Severe Weather Awareness Week in both North Dakota and Minnesota. It is a time set aside each spring to remind us of the potential hazards associated with thunderstorms as we move toward our warm season.
It is an excellent opportunity to setup your designated shelter and remind everyone in your household where to go in the event of a tornado or severe thunderstorm warning. This shelter is often the basement, especially under the stairs or a steady table. If you do not have a basement or garden level, head to the lowest level and get as many walls between yourself and outside for maximum protection. Manufactured home residents should familiarize themselves again where the emergency shelter is for their area and if you live in an apartment you can check with your landlord for the best place to go in your building.
With warmer temperatures expected the next several days a number of people have asked me if we can expect anymore snowfall this season. If history is our guide, I would not bet against seeing more snow this spring. Since records began in 1881, in approximately 40% of those years Fargo Moorhead has recorded measurable snow on this date or later and that does not count the numerous other years with flurries being reported.
One of the years when snow fell this late in the spring was last year. On April 25 and 26, 2008, 9.1 inches of snow fell officially in Fargo Moorhead. Some parts of the Minnesota lakes country reported 20-30 inches with a small pocket of three feet measured just south of Bemidji. Granted, that was one of the heaviest late season snowfalls on record, but in our climate, you may not want to put those snow shovels into storage until early May.
April 4 is the average date for our first 60 degree day of the spring season. The 62 degree high on Tuesday was 10 days past the average, but within the bounds of what would be considered average (for the statisticians out there, the standard deviation is 13 days). The historic range has been from February 25 in 1956 to May 6 back in 1893.
1893 and 1917 are the only two years in the record books without a high of 60 degrees or higher during the month of April. The most 60 degree days recorded in April was in 1987 which 22 such days were observed and that month was also the second warmest April on record. The long term April average is ten such days, so even with a slow start, April 2009 may yet finish near average for 60 degree days.
Mount Redoubt, a volcano situated to the southwest of Anchorage, Alaska has erupted several times in the past month. The strongest eruption had an ash cloud that rose to around 65,000 feet, with nearly a dozen other eruptions spewing ash to 60,000 feet. If Mount Redoubt behaves as it has in the past it may continue this pattern for several more months.
It has been known for years that volcanic activity can influence weather patterns around the globe. The ash and other aerosols released into the atmosphere from volcanoes can block a portion of the Sun’s energy from striking the earth, which has historically caused a net cooling of the planet. As of now, Mount Redoubt has not released enough ash for this to be a concern. Volcanic ash has another effect, brilliant sunsets and some of the ash may end up over our area this week, so be on the lookout for brighter evening colors.
There have always been two climatological records that I thought would never be broken in my lifetime. One being the all-time lowest temperature recorded in Fargo Moorhead, -48 degrees on January 8, 1887 and the other being the earliest 100 degree reading set back on April 21, 1980. After the completion of March, I have now added a third record to that list which is the 4.62 inches of rain and melted snow that was measured last month.
Before March 2009, the most significant difference between any one month’s first and second all-time wettest months was in June. The heavy rain event in June 2000 brought that month’s rain total to 11.71 inches, 25% higher than the previous record of 9.40 inches. Last month’s record setting rain was an incredible 63% higher than the previous record of 2.83 inches, which is likely a record that will not be broken for a long time.
If you are curious, 8 of the 12 months have a difference of 5% or less between the first and second wettest months on record, so indeed, March 2009 was a historic month for wet weather.
As the snow continues to slowly melt this week, if you look carefully you will notice an interesting phenomenon. Especially on the larger piles of snow, as the snow melts it will form ridges, or spikes protruding from the rest of the snow. On careful examination you will notice that these ridges will be generally pointed south toward the Sun as it is the Sun’s radiant heat that helps create them.
As a matter of fact, these ridges given a warm sunny day will follow the Sun through the course of the day and end up pointed toward the southwest by evening. Plus, if you would find that protractor you have not used since your 10th grade geometry class and measured the angle of the spikes in the snow you would discover that they match the angle of the Sun around solar noon, which would be approximately 45 degrees this week.
This image below is visible satellite image from Monday morning. All the white in the image is snow cover. If you look carefully, you will notice two "dark areas", one north of Fargo Moorhead and the other north of Grand Forks East Grand Forks. Both of those dark areas are overland flooding from the Red River.
April 6, 1997 brought some of the worst weather this area has experienced in the past 100 years. Heavy rain turned to freezing rain and finally a heavy wet snow that was blown around by 50 mph wind. It was the eight and final blizzard of the winter of 1996-1997 and it was probably the most powerful winter storm to hit this area since 1966.
Hundreds of power poles were snapped by the weight of the ice. By storm’s end, two to three inches of rain and melted snow fell on most of the southern valley. Thousands of people worked through the fierce blizzard laying sandbags as the waters were rising on area rivers. The town of Ada, Minnesota was evacuated as it was swamped by overland flooding. In Fargo Moorhead the Red River was rising rapidly and was sitting at 28.3 feet. It would eventually crest on April 17 at 39.57 feet.