The Atlantic Basin has been relatively quiet in recent days in terms of tropical activity and it continues to look like this will be a less active tropical season compared to 2017. One of the main factors that led us to an outlook for a less active tropical season back in the springtime was the large patch of colder-than-normal water at that time in the eastern Atlantic Ocean. This continues to exist and is quite likely an inhibiting factor for the formation or intensification of tropical activity in the tropical Atlantic and there are a couple other factors as well that are likely deterring activity. First, Saharan Desert (dry) air has persistently flowed westward from western Africa and into the tropical Atlantic and there are signs that this general pattern will continue into at least the near future. In addition, wind shear has been quite prominent across the tropical Atlantic in recent days and there are reasons to believe that this will continue to impede tropical activity in coming weeks. Don’t let your guard down; however, as all it takes is a direct hit by one storm to make it a memorable tropical season.
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In recent days, Arctic sea ice volume has been running at levels above the mean of the base period from 2004-2013 and it is above the levels seen during each of the past three years. Arctic sea ice extent has been relatively stable during the past decade or so albeit consistently at below-normal levels. This recent uptick in Arctic sea ice volume relative to prior years and the relative stability over the past decade or so in sea ice extent is related to long-term temperature trends in the Arctic region. Specifically, despite the fact that Arctic temperatures have often run at above-normal levels in the cold season during recent years, they have usually been running at nearly normal levels during the all-important summer melting season. Above-normal temperatures during the cold season in the Arctic are usually well below freezing which minimizes the overall impact on the melting of sea ice. The summer season is when temperatures are typically slightly above the freezing mark and any sustained warmer-than-normal conditions during those particular months would likely have an important impact on sea ice; however, this scenario has not been happening for many years.
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One of the most important stories in recent weeks in the world of weather and climate has been the abnormally cold waters of the northern Atlantic Ocean. This colder-than-normal patch of water just south of Greenland has been sustained for several weeks now and it is likely playing a role in Greenland’s extensive and abnormally high snow/ice pack for this time of year. In addition, this cold water just south of Greenland may be playing a role in overall colder-than-normal air temperatures in the Arctic region during their all-important summer melting season and the latest estimates of Arctic sea ice extent which compare favorably to recent years.
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One of the most widespread and destructive heat waves ever recorded in the US took place in the summer of 1936 which fell right in the middle of the hottest and driest decade ever for the nation. The decade of the 1930’s is renowned for the “Great Depression” and the “Dust Bowl”, both of which caused calamitous human suffering in this country. Not only were huge numbers of crops destroyed by the heat and lack of moisture in the “Dust Bowl” era, but thousands of lives were lost as a result of the heat, drought and economic hardship. Many of the all-time high temperature records that were set in the decade of the 1930’s still stand today. The heat wave experienced in 1936 began in late June, reached a peak in July, and didn’t really come to an end until September. This extreme heat wave was particularly deadly; especially, in high population areas where air conditioning was still in the early stages of development.
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The sun is blank today for the 15th straight day which is the longest stretch without sunspots since November 2009 when the sun was emerging from the deepest solar minimum in a century. This year the sun has been blank 52% of the time which is the most in a given year since the 71% that took place in 2009. The last solar minimum actually reached a nadir in 2008 when an astounding 73% of the year featured a spotless sun - the most spotless days in a given year since 1913 - and the longest consecutive streak in 2008 reached 52 days according to spaceweather.com. All indications are that the upcoming solar minimum may even be even quieter than the last one. One of the natural consequences of low solar activity is the weakening of the solar wind and its magnetic field which, in turn, allows for the intensification of cosmic rays and easier access to Earth. In addition, there tends to be a drop in total solar irradiance with the approach of a solar minimum.
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The high temperature forecast in Death Valley, California for the next couple of days is an impressive 115°F or so, but this is rather pedestrian compared to the all-time record high that occurred on this date one hundred and five years ago. On July 10th, 1913, the weather observer at Greenland Ranch in Death Valley recorded a high temperature of 134°F. One hundred and five years later, this is still the highest air temperature ever reliably recorded on Earth. In addition to this all-time and worldwide high temperature record, the year of 1913 produced numerous other extreme weather events.
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The summer solstice has just passed and the days will grow shorter and shorter from here on out until the winter season gets underway. While winter is still a long way off, there are already some clues that can provide some insight as to what kind of weather we can expect around here in the Mid-Atlantic region. First, signs point to the formation of warmer-than-normal sea surface temperatures by the upcoming winter season in two key areas of the Pacific Ocean: 1) the central equatorial region and 2) the Gulf of Alaska. Second, there is little doubt that solar activity will remain on the low side through the upcoming winter season as we are rapidly approaching the next solar minimum phase from an already historically weak solar cycle #24. Finally, one important wintertime cold air source region for the Mid-Atlantic is Greenland and it is currently experiencing above-normal snow and ice cover. While this is in the speculation phase, all of these factors point to the possibility of cold and snowy conditions in the Mid-Atlantic region during the upcoming 2018-2019 winter season.
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The Atlantic Basin tropical season is still rather young having “officially” just begun a few weeks ago on June 1st, but there have been two factors so far that have suppressed activity and they may not let up anytime soon. First, sea surface temperatures have been running at below-normal levels in the all-important "breeding grounds" region of the tropical Atlantic Ocean in the region extending from the west coast of Africa to the Caribbean Sea. Second, there has been a persistent flow of dry air moving westward from the Sahara Desert region of Africa into this same "breeding grounds" region of the tropical Atlantic Ocean. Both of these factors tend to inhibit the formation of tropical storms or the intensification of storms that actually do manage to form.
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In recent days, Arctic sea ice volume has reached nearly normal levels when compared to the period of 2004-2013 for this time of year and it is noticeably higher than one year ago. Arctic sea ice extent has been relatively stable during the past decade or so albeit consistently at below-normal levels. This recent uptick to near normalcy in sea ice volume and the relative stability over the past decade or so in sea ice extent is related to long-term temperature trends in the Arctic region. Specifically, despite the fact that Arctic temperatures have often run at above-normal levels in the cold season in recent years, they have usually been running at normal to slightly below-normal levels during the all-important summer melting season. Above-normal temperatures during the cold season in the Arctic are usually well below freezing which minimizes the overall impact on the melting of sea ice. The summer season is when temperatures are slightly above the freezing mark from a climatological viewpoint and any sustained warmer-than-normal conditions during those particular months could have an important impact on sea ice; however, this just has not been happening over an extended period of time.
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Solar cycle 24 is rapidly approaching the next solar minimum and while the sun currently has three sunspots region visible to Earth, much of the year has seen a spotless sun. In fact, the sun has been blank on 73 days in 2018 which amounts to 57% of the year. The last time the sun was this blank in a given year on a percentage basis was 2009 during the last solar minimum when 71% of the time was spotless. That last solar minimum actually reached a nadir in 2008 when an astounding 73% of the year featured a spotless sun - the most spotless days in a given year since 1913. The current solar cycle is the 24th solar cycle since 1755 when extensive record-keeping of sunspot activity began and it on pace to be the weakest sunspot cycle since cycle 14 peaked in February 1906. As a result of the last unusually long and deep solar minimum and very weak bounce back during solar cycle 24’s maximum phase, much attention will be focused on the rapidly approaching solar minimum and subsequent solar cycle #25 to see if the sun may be entering an extended period of quiet.
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