Arctic sea ice extent has likely just reached its low point of the melting season and is above levels from 2012 and 2007 at this same time of year. Arctic sea ice generally shrinks every year during the spring and summer seasons until it reaches its minimum yearly extent around this time of year. Sea ice then typically regrows during the frigid fall and winter seasons when the sun is below the horizon in the Arctic. The apparent end to this year’s melting season in the Arctic is right around the mid-point of September.
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The high temperature forecast in Death Valley, California for the next couple of days is an impressive 120°F or so, but this is rather pedestrian compared to the all-time record high that occurred on this date one hundred and four 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 four 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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While we were celebrating our Independence Day on July 4th, Summit Station in Greenland may have experienced the coldest July temperature ever recorded in the Northern Hemisphere at -33°C (-27.4°F). Much of Greenland has been colder-than-normal for the year so far and has had record or near record levels of accumulated snow and ice since the fall of last year. The first week of this month was especially brutal in Greenland resulting in the record low July temperature and it also contributed to an uptick in snow and ice extent - despite the fact that it is now well into their summer season.
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The sun is currently featuring one lonely visible sunspot region and this relatively blank look is becoming more and more common as solar cycle 24 heads towards the next solar minimum. In fact, there have been 42 days in 2017 with a completely blank sun – already ten more days than all of last year – and this makes up almost one-quarter of the time for this year. Solar cycle 24 has turned out to be historically weak with the lowest number of sunspots since cycle 14 peaked more than a century ago in 1906. In fact, by one measure, the current solar cycle is the third weakest since record keeping began in 1755 and it continues a weakening trend since solar cycle 21 peaked in 1980. One of the natural impacts of decreasing solar activity is the increase of cosmic rays that can penetrate into the Earth’s upper atmosphere and this can have many important consequences.
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A weak El Nino instead of a moderate-to-strong one would allow for a more active tropical season in the Atlantic Basin. In addition, should a weak El Nino persist into the upcoming winter season and be concentrated in the central tropical Pacific Ocean (Modoki), it could increase the chances for a snowy winter in the eastern US. Earlier this year, it looked as though a moderate-to-strong El Nino was a sure bet as sea surface temperatures shot up to well above normal levels just off the west coast of South America. In addition, numerous computer forecast models at that time supported the idea of a moderate-to-strong El Nino in the tropical Pacific for the summer and fall seasons. Recent actual observations, however, indicate El Nino is sputtering and many computer forecast models have now backed away from a moderate-to-strong El Nino and this potential change could indeed have some important implications.
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This could very well be just a temporary blip, but Arctic sea ice extent has actually crossed into territory in recent days that it hasn’t seen too often in many months. Specifically, Arctic sea ice extent as measured by the European global operational satellite agency (EUMETSAT) has moved into the relatively “normal” range of +/- 2 standard deviations – albeit on the very low side of “normal” for this particular time of year. Arctic temperatures have dropped to below-normal levels in recent weeks after running consistently above-normal for the first four months of the year and this has slowed down the normal springtime melting in that region.
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Earlier this year, it looked as though El Nino was beginning to form in the tropical Pacific Ocean with warmer-than-normal sea surface temperatures becoming more evident off the west coast of South America. In addition, numerous computer forecast models were predicting moderate-to-strong El Nino conditions for the summer and fall seasons in the equatorial region of the Pacific Ocean. While this can still happen, recent actual observations have raised some questions about those predictions. One of the reasons it is necessary to closely follow the changes in the tropical Pacific Ocean is the fact that it can have an important consequence on the rapidly approaching Atlantic Basin tropical season. In an El Nino year, for example, there is a tendency for less tropical activity in the Atlantic Basin as El Nino-induced vertical wind shear is typically higher-than-normal and this tends to inhibit the growth of tropical storms.
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It is not often that “severe”, “extreme” or “exceptional” drought conditions are limited to only 1.58 percent of the continental US, but that is exactly what we have right now across the country. We know that these good times will not last for too much longer; nonetheless, it is worth noting that this is about as good as it gets for the US regarding drought. In fact, going back to the year 2000, only the early part of 2010 featured somewhat similar limited drought conditions on a nationwide basis to what we are enjoying today. Just under five years ago in August of 2012, the nation was at a real dry point and nearly 25 percent of the country was classified with “extreme” drought.
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Today marks the 6th day in a row that the sun is blank and the 36th time this year - already more spotless days than all of 2016. In what has turned out to be a historically weak solar cycle (#24), the sun continues to transition away from its solar maximum phase and towards the next solar minimum. In April 2010, the sun was emerging from the last solar minimum which was historically long and deep. The blank look to the sun will increase in frequency over the next couple of years leading up to the next solar minimum - probably to be reached in late 2019 or 2020. By one measure, the current solar cycle is the third weakest since record keeping began in 1755 and it continues a weakening trend since solar cycle 21 peaked in 1980. One of the impacts of low solar activity is the increase of cosmic rays that can penetrate into the Earth’s upper atmosphere and this can have many important consequences.
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The overall numbers are likely to be near normal this year in terms of the number of Atlantic Basin (includes the Caribbean Sea and Gulf of Mexico) tropical storms and the sea surface temperature pattern in the western Atlantic and Caribbean Sea makes the southern and eastern US somewhat vulnerable to “home-grown” tropical hits. The major factors involved with this year’s tropical outlook include an unfolding weak El Nino in the equatorial Pacific and a mixed picture of warmer-than-normal and colder-than-normal patches of water across the Atlantic Basin.
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