Continental vs Maritime

The temperature this month in Fargo Moorhead has ranged from eleven below zero to 75 degrees for a range of 86 degrees in a month.  It’s hard to dress for that.  Fargo Moorhead is a perfect example of a continental climate in which the temperature can vary as air is blown around the region by various random weather patterns.  The greatest one-day range was 44 degrees on March 14 when it was 24 in the morning and 68 in the afternoon.  In contrast to this, the temperature this month in Key West, Florida, has ranged from 69 degrees to 84 degrees for a range of 15 degrees.  The greatest one-day range was 13 degrees from a low of 69 to a high of 82.  Key West weather is maritime.  The temperature of the surrounding ocean dominates the weather, keeping daily as well as day-to-day changes minimal.  Meteorologist John Wheeler

First Day of Nothing

Friday, March 20, is the Vernal Equinox.  Many people call this the first day of spring without thinking much about it.  Can spring start at the same moment everywhere on Earth?  Think about the equatorial regions.  At the equator, March and September are when the sun is directly overhead at noon.  It is hot all year at the equator.  But it is often hottest in March and September.  The weather is also rainiest and most humid along the equator around the time of the equinoxes because the direct sunlight causes peaks in evaporation rates to go along with the peaks in temperature.  Around the time of the Solstices in winter and summer, the middle of the world has its two slightly less hot seasons.  So there are relationships between the equinoxes and weather, but they are general and varied around the world.  The Vernal Equinox is really an astronomical moment with no immediate impacts on the weather anywhere.  This makes the “first day of spring” a fairly useless concept.    Meteorologist John Wheeler

Quiet Atlantic Hurricane Season

The Atlantic hurricane season officially comes to an end this weekend.  It was a good year for people and a bad year for hurricanes.  There were just eight named tropical systems (sustained winds of at least 39 mph) in the Atlantic Basin.  Six of them became hurricanes (sustained winds of at least 74 mph).  Only two became major hurricanes (Category 3,4,5 with winds of at least 111 mph).  The relative absence of hurricanes is due to the absence of good hurricane conditions.  Upper level winds over the tropical Atlantic were strong and kept clusters of thunderstorms from becoming organized.  Also, a lot of dry air was in place over the Atlantic. On the other side of the Americas, the eastern Pacific was the most active since 1992.  It is not uncommon for the two oceans to be out of sync like this.  The record year for Atlantic hurricanes, 2006, was a very quiet year across the Pacific.  Meteorologist John Wheeler

The American Monsoon

July and August is the time of the American Monsoon.  During June and early July, the desert areas from northern Mexico northward into the Rocky Mountain States heat up from day after day of sunny weather.  Temperatures reach well into the 100s at lower elevations, and sometimes into the 110s and 120s in parts of Arizona and California.  The hot air becomes less dense (with lower barometric pressure).  During July and August, air moves in from all around in response to the lower pressure, but mountain ranges block much of this movement except for a stream of tropical air from the eastern Pacific which comes by way of the Gulf of Baja.  The higher humidity in this air leads to frequent thunderstorm activity over the mountains of the Southwest.  Ironically, this is also the peak of the Southwestern fire season as some of the mountain storms produce lots of lightning and very little rain.   Meteorologist John Wheeler

Soccer in the Jungle

Manaus, Brazil, is hosting Sunday’s FIFA World Cup match between the teams from the U.S.A. and Portugal.  Manaus is a city of two million people located at the confluence of the Negro and Solimões River, both important tributaries of the Amazon. The city has been populated since the late 1600s, so it is certainly metropolitan.  That being said, Manaus is actually located 900 miles inland from the Atlantic Ocean well within the Amazon rain forest.  One travels to Manaus by plane or boat.  One does not drive there from Rio de Janeiro.  The weather is that of a tropical rain forest.  Temperatures are usually in the 80s with dew points in the 70s. Usually there is very little wind.   There are frequent thunderstorms, often with heavy rain.  The stadium is a brand new, 40,000 seat arena.  It is open to the weather over the pitch but the roof is designed to keep most of the spectators out of any rain.  John Wheeler

Haiyan or Yolanda?

One of the most powerful tropical cyclones on record hit the Philippines last Friday and then moved in southeast Asia over the weekend.  That storm was known as Typhoon Haiyan in international circles, but if you followed this event via the Internet, you may have noticed that some individuals were also referring to the storm as Typhoon Yolanda.  

Yolanda was the name given to the storm by the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAG-ASA).  Any tropical system that has the potential to impact the Philippine islands the PAG-ASA assigns a Filipino sounding name, not necessarily names of people, to the storm to make it easier to be remembered.  The Philippines average around 20 named systems a year, far more than usually impact other countries in the world, making easily recognizable names very important for the country.  

Yolanda was the 24th system named this year by the PAG-ASA.

Orange Tornadoes

Last week on Halloween, 42 tornadoes were reported across the country.  Most of those were confirmed with storm survives over the following days.  That was the most tornadoes reported on October 31 since at least 1950.  That was also the highest daily tornado count in the United States since early July.  

Yet, even with a high number of tornadoes recorded last week, the 2013 season overall has been one of the quietest since good severe weather records started in 1950.  Not only has the tornado season been quiet, but so has the Atlantic hurricane season.  Through October the Accumulated Cyclone Energy (ACE) index was the 4th lowest since 1950 for the Atlantic basin.  

Plus, it will probably be another year without a major hurricane strike on the lower 48 states, continuing the longest such streak since at least the Civil War.

ACE is the Word

A widely used tool for analyzing the strength of a hurricane season is the Accumulated Cyclone Energy or ACE index.   The ACE index combines the number, strength and duration of tropical systems into a set mathematical equation.  This can give a much better insight into the differences between tropical seasons rather than just counting the number of storms alone.

For instance, although the North Atlantic Hurricane season has now recorded 11 named systems, the accumulated ACE score for the year is running at less than 30% of average.  The average is based on the years 1981 through 2010.  The North Atlantic basin is not the only region recording well below normal ACE scores this year.  In fact, globally, all tropical regions are running below normal for ACE scores.  Taken as a whole, global ACE numbers this year are running at only 54% of average.  

The past several years have also recorded a below average ACE, likely attributed to a recent switch to cooler Pacific Ocean temperatures. 

Lack of Majors

The last time the United States was struck by a major hurricane (Category 3,4 or 5) was on October 19, 2005 when Wilma impacted Florida.  2005 was an exceptionally busy year for land falling hurricanes in the country.  This current period without a major hurricane hitting the lower 48 states is the longest since at least the Civil War. 

Some may say we are “overdue” for a major hurricane to hit somewhere in the country, but of course, the atmosphere does what it does and through the centuries periods of active and less active stretches have always occurred.  Back in 1954 the east coast recorded three major hurricanes in less than 10 weeks, which is no more abnormal than our current stretch of nearly eight years without a major hurricane.   

As we learned with Hurricane Sandy just last year, it does not take a major hurricane to cause horrific damage along the heavily populated coastal areas of the United States.  The streak will eventually end and it could easily do so yet this year. 

George Washington’s Hurricane

On July 23-24, 1788 a hurricane moved through the Mid-Atlantic States.  That storm is often referenced as the George Washington Hurricane as it was mentioned in his diary.  As the storm approached Virginia from the east, the wind began to pick up considerably from the northeast on July 23.  Then in the very early hours of July 24 the wind quickly and suddenly shifted to the south and “blew a perfect hurricane, tearing down chimneys and fences”.

That shifting wind from the northeast to the south indicates that eye of that particular hurricane passed right over Mt. Vernon.  The storm caused extensive flooding with many drowning victims reported.  Also, extensive crop damage was reported with several ships driven on shore.  Plus, Washington mentioned that a small ship, The “Federalist” sank during the storm.

From the descriptions of others who also wrote of this storm in their diaries, Mt. Vernon fared better than others, as James Madison, father of the future president said the damage was “beyond description” in  Alexandria, Virginia.