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

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

The Year Without a Summer

It is well-known that large volcanic eruptions can have a significant effect on world weather due to the introduction of sun-blocking sulfate aerosols into the stratosphere.  The Krakatoa eruption of 1883 likely contributed to a string of very cold years in the middle and late 1880s. The Pinatubo eruption of 1991 preceded Fargo Moorhead’s coldest summer in 75 years in 1992. The 1815 Tambora eruption has, for decades, been associated with the infamous 1816 “Year Without a Summer,” in which summertime snow and frost caused crop failures across New England as well as many parts of Europe.  Newly rediscovered writings from a South American scientist produced evidence of a strong eruption in Columbia in 1808 which likely added to the Tambora cooling.  According to other geological data as well as limited record keeping of crops, the first two decades of the 1800s produced some of the coldest years of the past several hundred years and this new evidence helps explain why.   Meteorologist John Wheeler

Earliest Snow, Earliest Cold

On September 25, 1912, it snowed in Fargo Moorhead.  The summer of 1912 had been hot and very dry and the heat wave had continued into the early part of September.  Three of the first eight days in September were in the 90s.  But it began to rain September 12.  It rained on 12 of the next 14 days.  During this time, the weather turned remarkably cooler.  Daily high temperatures dropped into the 50s starting September 14.  There was a light frost on September 16.  On September 24 and 25, a steady rain accumulated to more than one inch with the temperature hovering around 40 degrees.  And late on September 25, the cold rain turned to snow, accumulating two inches on the ground during the night.  It remains the earliest measurable snow in Fargo Moorhead recorded history.

On September 26, 1965, it was 19 degrees in Fargo Moorhead.  The month of September, 1965, had been cool from the start.  It had been that cloudy, cool, dank weather that sometimes settles in during the fall for long periods.  Most days were in the 50s.  Frost had not happened due to the perpetually cloudy weather.  But on September 24, the sky cleared but it only warmed to 62 degrees.  That night, it turned unusually cold.  By midnight, the temperature had reached 29 degrees, and by morning it was 22.  The following day, September 25, it remained sunny but the high was just 55 degrees.  The following morning, the temperature bottomed out at 19 degrees.  This remains the earliest temperature in the teens in Fargo Moorhead weather history. The next three days, the clouds returned and highs were only in the 40s, but there was no more frost until early October.  The winter of 1965-66 was bitterly cold but is most famous for the terrible blizzard of March, 1966, considered by most climatologists to have been the strongest blizzard of the 20th Century on the Great Plains.

Meteorologist John Wheeler

 

Tornadoes #14 and #15

Friday evening, September 19, a supercell thunderstorm produced a sequence of two tornadoes in northwestern Minnesota.  The first tornado touched down near Northcote and on U.S. 75 and travelled east, crossing U.S. 59 south of Lancaster before lifting and travelling a bit further as a funnel cloud.  There was quite a bit of damage to a number of farm buildings in central Kittson County.  The tornado earned an EF2 rating, indicating peak winds between 111 and 135 mph.  the storm then produced a second tornado which traveled several miles across western Roseau County west of Greenbush.  This storm was earned an EF1 rating, suggesting winds between 86 mph and 110 mph.  Though neither tornado would have been considered a “monster” storm, it was an impressive feat for so late in the storm season.  Despite the late-season tornadoes, 2014 continues to be a relatively benign year for tornadoes in our region.  Those two tornadoes Friday were only the fourteenth and fifteenth tornadoes this year over eastern North Dakota and northwestern Minnesota, and the first since July.    Meteorologist John Wheeler

Late-Season Hot Temperatures

On September 22, 1936, it was 101 degrees in Fargo Moorhead.  This is the latest 100 degree day ever recorded here.  The record highs for each day are mostly in the 90s through October 6, after which the record highs are in the 80s until one rogue 90 degree day shows up from October 17, 1910.  The latest 80 degree day in the books was set on October 25, 1989, at 83 degrees.  The latest 70 degree day was the 73 degree day set November 1953.  The latest day in the 60s was the 65 degree afternoon on December 6, 1939.  The coldest record high for any day is 40 degrees, for several different days in January.    Meteorologist John Wheeler