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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To be fair, most of the computer model predictions of a transition from La Nina (colder-than-normal) to El Nino (warmer-than-normal) in the equatorial Pacific Ocean suggest this will take place over the next few months, but the track record of these same models from just one year ago is not all that confidence-building and the latest 7-day change in sea surface temperatures is certainly not yet showing any kind of dramatic turnaround. The overall conditions in the equatorial Pacific Ocean are very important to the Atlantic Basin tropical season which officially begins in just over one month’s time. Computer forecast model predictions of an El Nino last year were simply not accurate and the surprise return of La Nina late last summer contributed to the suddenly very active tropical season of 2017.
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As we know full well here in the Mid-Atlantic region, there have been an unusual frequency of late winter and early spring cold air outbreaks leading to consistently below-normal temperatures during March and April. This extended period of unusual cold has also impacted other parts of the nation including the Ohio Valley, Great Lakes, central and northern Plains, and parts of the Southeast US. The late season cold has also had an inhibiting effect on the tornado season so far across much of the US with overall numbers way down compared to normal. In fact, the state of Oklahoma – right in the heart of tornado alley – is about to set a record for their latest first tornado ever.
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While consistently at below-normal levels since the mid 1990’s, Arctic sea ice extent has stayed relatively stable during the past decade or so. This recent stability in Arctic sea ice extent is likely due mainly to the fact that temperatures have been regularly near-normal during the all-important summer season and peak melting time of the year. Temperatures have often run at above-normal levels during the cold season in the Arctic, but during those particular months, conditions are usually well below freezing which minimizes the impact on the melting of sea ice. In the summer season, Arctic temperatures are slightly above the freezing mark from a climatological viewpoint and this is the time of year when sustained warmer-than-normal conditions could have an important impact on sea ice extent, but it just hasn’t been happening that way in an extended period of time.
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The sun is blank today for the 10th straight day and it has been without sunspots this year more than half the time as the current solar cycle (#24) heads towards the next solar minimum. 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. All indications are that the upcoming solar minimum may be even quieter than the last one which was the deepest in nearly a century. 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.
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The sun is blank today for the 10th straight day and it has been without sunspots this year more than half the time as the current solar cycle heads towards the next solar minimum. Solar cycle 24 is currently on pace to be the weakest sunspot cycle with the fewest sunspots since cycle 14 peaked in February 1906. Solar cycle 24 continues a recent trend of weakening solar cycles which began with solar cycle 21 that peaked around 1980. 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.
All indications are that the upcoming solar minimum which is expected to begin in 2019 may be even quieter than the last one which was the deepest in nearly a century. One of the natural impacts of decreasing solar activity is the weakening of the ambient solar wind and its magnetic field which, in turn, allows more and more cosmic rays to penetrate the solar system. The intensification of cosmic rays can have important consequences on such things as Earth’s cloud cover and climate, the safety of our astronauts exploring in space, and lightning.
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High-latitude blocking refers to an atmospheric pattern in which higher heights (and pressure) compared to normal sets up in high latitude regions such as Greenland or northern Canada and it can remain in place for an extended period of time leading to a large-scale obstruction of surface weather systems. High-latitude blocking tends to be more likely during periods of low solar activity and that is certainly the case now as (weak) solar cycle 24 heads towards the next solar minimum. During the latter stages of winter, this type of setup can result in a persistent colder-than-normal weather pattern for the central and eastern US and perhaps stormy conditions as well. All signs point to a strong high-latitude blocking pattern to develop later this week across the North America side of the North Pole and this virtually ensures winter will not go down without a fight in March in the central and eastern US. This change in the overall pattern will also likely result in the generation of a powerful ocean storm late this week just off the Mid-Atlantic coastline and it will likely be a slow mover.
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There has been a major stratospheric warming event over the past couple of weeks with a displacement of the polar vortex to lower latitudes and over the next several days a significant high-latitude blocking event will unfold leading to way above normal heights over places like Greenland and northeastern Canada. These large-scale atmospheric events are having an impact on weather patterns all across the Northern Hemisphere. They will be contributing factors to the extreme cold that is about to invade Europe from the east (Siberia) and to a cold pattern that looks like it will develop across much of the US during March which may feature a nor'easter during the transition period late next week.
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While the South Pacific has held its breath over the fate of Bali’s roaring Mount Agung, another volcano in the vicinity has been letting off its own steam. Mount Sinabung is among more than 120 active volcanoes in Indonesia, which is prone to seismic upheaval due to its location on the Pacific "Ring of Fire," an arc of volcanoes and fault lines encircling the Pacific Basin. The volcano in North Sumatra, which has been active since 2010 after centuries of dormancy, had its strongest eruption in five years on Monday morning.
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