Coriolis Explained

Tuesday, October 21, 2014

While it is true that air rotates around large low-pressure systems in the opposite direction south of the equator, it is a myth that the water in a toilet swirls in the opposite direction down there.  The Coriolis Force is an apparent force caused by the rotation of the Earth. The rotating Earth causes apparent deflection of moving objects to the right in the Northern Hemisphere; to the left in the Southern Hemisphere. What’s actually happening is that air is moving straight and it is the Earth turning that makes it look look like it is curving.  This is what causes large scale storm systems (including hurricanes, low-pressure systems, and most tornadoes) to rotate counterclockwise in the North but clockwise Down Under.  However, the effect is virtually negligible on any movements the scale of modern plumbing.  Motions caused by the plumbing design or a person swirling the water has a much greater effect.  Meteorologist John Wheeler

Forecast For Winter

The Climate Prediction Center (CPC) issued its winter prediction this week and, based largely on the forecast of a weak El Nino developing, have given our area an increased likelihood of above normal temperatures for averaged from December through February.  This means they think it is more likely to be warmer than normal than near-normal or below-normal.   When it comes to long range winter forecasting, there is hardly a better indicator than the presence of El Nino or La Nina.  Unfortunately, even these are not as reliable as we would like them to be.  Conditions in the Pacific Ocean are neutral at the moment, but there are signs of a weak El Nino forming early in this winter.  The CPC has had more trouble than usual with winter forecasts lately because factors other than El Nino/La Nina have been trumping the winter weather regime.  The past few weeks, widespread, substantial snow cover has spread across most of Siberia, often a sign of a colder winter in our region.  In other words, we really do not know what the winter will bring.  Long range forecasting is not quite the same as guessing wildly, but it isn’t much better.   Meteorologist John Wheeler

New MNDOT Winter Driving Terms

As you may have heard by now, the Minnesota Department of Transportation has come out with new terminology to better clarify winter road conditions.  The old terms; good, fair, poor, travel not advised, and closed are out.  The new terms; normal, partially covered, completely covered, travel not advised, and closed are in.  However, this might not be enough.  I often get inquiries from people who, apparently, have either vehicles or superpowers which make them impervious to weather.  These people, after hearing the road report, want me to tell them how bad it really is.  Some people, apparently, require a few more terms for those conditions when roads are worse than just closed. Might I suggest, “completely closed,” “closed beyond belief,” and finally, from the Book of Amos, “Woe to them that are at ease in Zion.”     Meteorologist John Wheeler

October Severe

Wednesday, October 15, 2014

The high number of severe weather reports (damaging wind, hail, tornado) from the Southern Plains across the Southeastern U.S. Sunday this week is a lot for the middle of October.  When a weather system develops which is out of character for the time of year, many people’s reaction is to ask what has gone wrong to allow for this.  In fact, however, the weather does not always know what season it is.  While the low pressure system this week was stronger than is typical for October, the main reason for all the strong thunderstorms was twofold:  Very humid air brought up from the tropical part of the Gulf of Mexico and wind blowing at different velocities at different levels of the atmosphere.  In other words, so many thunderstorms became severe because conditions were right for severe storms, in spite of the calendar.  The outbreak of storms this week is no more unusual than an early frost or a mid-winter mild spell. It’s just another case of the weather being the weather.    Meteorologist John Wheeler

Memorable Early October Snow

On October 7, 1985, the Fargo Moorhead area just missed out on a major early season snowstorm.  Grand Forks got six inches from the storm, Roseau received eight inches, and Langdon got ten inches.  The heaviest snow fell in north-central North Dakota where Minot got a foot of snow and Velva received 17 inches.  The autumn of 1985 was much colder than average and, although most of that early snowfall melted within a few days, several major November snowstorms blanketed our entire region to a depth of one to three feet by Thanksgiving.  Here in Fargo Moorhead, the last five days in November were all below zero day and night.  Such a cold snap before December is unusual.  And though the weather remained cold until just before Christmas, most of January, February, and March brought above-average temperatures.  That was my first winter at WDAY and I remember it well.  The early snow and cold was exciting professionally, but a bit of a shock personally.   Meteorologist John Wheeler

Another Summer of Thin Ice

Although the Arctic summer of 2014 was cooler and less stormy than average, Arctic sea ice reached its sixth lowest extent since 1978 according to The National Snow and Ice Data Center in Boulder, Colorado.  On September 17, ice covered 1.94 million square miles, compared to the 1981-2010 average of 2.40 million square miles.  Ice cover on the Arctic Ocean always retreats in summer, usually reaching a minimum in September before cold weather causes the ice to rebuild.  Warming in recent years has contributed to a general decline in the amount of the Arctic Ocean covered in ice at the end of summer.  The ice will continue to increase through the fall and winter, before reaching a maximum coverage sometime next spring.  Arctic temperatures have been on the rise since the 1800s.  However, satellite measurement of Arctic ice has only been possible since the late 1970s.   Meteorologist John Wheeler

Wind Energy Grows, Remains Small

Wind power and solar power are the two fastest growing means of generating electricity according to Worldwatch Institute.  However, this still accounts for just a small percentage of electricity generated in the United States.  According to the U.S. Department of Energy, Electricity used in America is 30 per cent from coal and 27 per cent from natural gas.  Nuclear reactors generate 19 per cent.  Hydropower accounts for 7 per cent.  Wind energy, although growing, produces around 4 per cent of our electricity and solar power creates less than a half of a per cent.  Most of the remaining percentages come from a variety of renewable resources such as biomass and geothermal.     Meteorologist John Wheeler

An Up and Down, Average September

The month of September finished with relative average statistics despite a lot of ups and downs.  The month began warm and rainy.  The first eight days of September brought highs in the 70s and 80s.  A rainfall of 1.99 inches occurred on September 4, which was about 80 per cent of the total for the entire month.  The middle of the month brought a cool spell before the warmest weather in September happened near the month’s end.  The warmest temperature was 87 degrees on September 27.  The coolest was 39 degrees on September 13. The average high for the months was 72.2 degrees and the average low was 49.5 degrees.  The 2.45 inches of rain is 0.12 inches below average.  The mean daily temperature average of 60.8 degrees is 1.7 degrees above average.    Meteorologist John Wheeler

Winter Forecast (NOT!)

If you want to be both amused and annoyed, do an internet search of “winter forecast” and see what comes up.  You will read about El Nino and what it means this winter.  You will later stumble across other ideas about what it means which will severely contradict the earlier meanings.  You will read personal rants in various comments sections from people who know little about long-range forecasting but know a lot about how to shout when writing.  You will read about how last winter’s forecasts were right in some places and wrong in others.  You will stumble across the Old Farmer’s Almanac and recall how their forecast is almost never correct despite its claim that it is right 80 per cent of the time.  You will read their forecast and tell yourself you do not believe it but you will believe it a little.  After a while, you will get bored and find something else to look at.  In the end, you will have no idea how the upcoming winter will be.   Meteorologist John Wheeler

First Hard Freeze

The first hard freeze of fall is one of those truly great moments of the year.  So many things change that one morning.  So much of what had been growing and green turns dead, brown, and black and there is no way back from the first freeze in the fall.  Most years, the first hard freeze happens in October although occasionally it comes early, in September.  There are, of course, places on Earth that do not freeze in our present climate. In Key West, the vines and the palms just keep growing and people have to work to keep the jungle out of their yard. Southern California will get a killing freeze now and again.  But a northern killing freeze is a dependable, once-a-year, life-changing event.  It is a milestone and a harbinger and in that sense, some hate what it stands for.  But it always comes and it will come one morning soon and I will find comfort in not having to worry about my garden any more.    Meteorologist John Wheeler