Major Pattern Change for North America and Arctic Next Week.

A major weather pattern shift will be occur next week for North America into the Arctic as the jet stream…which already has been largely higher in amplitude and experiencing some blocking with little eastward progression of long-waves in the upper-atmosphere, will becoming extremely amplified (north-south) next week bringing very warm air up into Alaska, Yukon and the Arctic Ocean and a modified Arctic air mass from Nunavut and the Northwest Territories of Canada into the central US. Let’s take a look at things.

The current pattern dominating North America has been strong ridge of high pressure over the Western US or Eastern Pacific with a prominent trough over the eastern US with some fluctuation in the wave pattern east or west, but not much significant change, except in the center of the country which has seen more significant swings between these two states. The east, including even the Southeast saw significant snow. The west has seen abnormal warmth with record fires in California. Currently the ridge of upper-atmosphere ridge is forecast by US and European models to build to an extremely high amplitude the end of next week north over portions of Alaska and Yukon and into the margins of the Arctic Ocean. This as a very intense trough is forced south over the US.

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European model forecast for the wave pattern of the mid-level atmosphere valid 6 pm CST 12/23.

This extreme amplification will drive an Arctic surface air high pressure system out of the Northwest Territories with very cold air this week, with this air mass advancing into the US beginning Thursday into this weekend. Meanwhile stormier conditions will moving from the Bering Sea into the Chukchi Sea driving up temperatures in the far north. And California with all the fires? Remains abnormally warm and dry.

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Temperatures the afternoon of Christmas Eve (European Model forecast).
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Greatest signal for low to no precipitation the next 10 days is south-central to southern CA into much of AZ and NV.

The Arctic:

As I spoke about in a previous post, the Arctic is having its second warmest year on record and lowest annual sea ice volume on record as climate change continues to abnormally warm the Arctic. The highly amplified wave pattern is much a product of the current weak La Nina pattern. However, the intensity of the amplification and resulting amplified warming of the Arctic is also a function of the long-term global warming regime dominating the polar region and causing record warmth and reductions in sea ice. I noticed this amplified wave pattern will have interesting impacts on the Arctic weather pattern and possibly the tenuous sea ice beginning next week.

Right now, a prominent surface high pressure region…associated with the Beaufort Gyre…is over the Arctic Ocean north of Alaska and eastern Siberia. By the middle of next week, this gyre will weaken as strong low pressure systems approach the Arctic from both the Bering Sea and the far North Atlantic.

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Prominent high pressure of the Beaufort Gyre over the sea ice of the Arctic Ocean.
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European Model depiction of low pressure system advancing into the Arctic Ocean from the Bering Sea on Christmas Eve. This may be the strongest in a series of lows (2-3) beginning late week. Stormy conditions will also impact areas near Svalbard (islands just east of northeast Greenland) late-week and weekend.

The Gyre is vulnerable because of the areas of open water and tenuous sea ice which remains over the Chukchi Sea…record low extent for this time of year. The ice being cold creates the surface high pressure system and clockwise circulation. But last year, this gyre collapsed because of slow sea ice growth allowing for storms with warm, moist air to move into the Arctic and further slowed sea ice growth. It appears this may be forecast to happen again during the tail end of this month.

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European Model forecast surface temperatures showing well above normal temps shifting northward late week into Christmas Eve over the Arctic Ocean north Svalbard and the Chukchi Sea. While exact values will change, general pattern appears likely.

Depending on the strength of the low pressure systems, not only will the tenuous sea ice in the Arctic…widespread areas 1.5 meters or less in thickness (less than a meter in the Chukchi Sea)…deal with more warm air temperatures limiting sea ice growth, but also wave action which may destroy the ice, particularly from the Pacific side as cyclones are expected to move across the Arctic from the Pacific. We’ll see how much impact those storms have and how intense they are. If the upper-level wave pattern is as amplified as forecast by models 5-8 days out (no reason to think otherwise as he reach the point of good reliability for the upper-atmosphere), it’s a good set up for strong low pressure systems to develop in both the North Pacific and North Atlantic. And with the highly amplified blocking high over the Eastern Pacific, storms will be forced to track into Alaska and into the Chukchi and Beaufort Seas and deep Arctic Ocean.

–Meteorologist Nick Humphrey

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Arctic Sea Ice Extent Rapidly Decreasing Because of Climate Change; Weather & Climate Implications

Today, NOAA presented the State of the Arctic report at the American Geophysical Union annual conference in New Orleans. The news from the report was devastating for potential weather and climate impacts. Lots of important info to talk about from this! Let’s summarize:

  1. Annual Arctic sea ice extent is the lowest in 1600 years. This is based on proxy data (tree rings, lake sediments, ice cores from the Greenland Ice Sheet). There has been an abrupt decrease in extent during the 20th century (continuing to present). 24991395_10215050817330895_108575701643656859_n
  2. Arctic sea ice extent reached a record minimum in the warm season in 2012. However, 2015-17 witnessed consecutive record low maximum extents in the cold season. 2016 also had the lowest extent on record in November or December. 2017 is also witnessing top two or three low daily extents in November into December, with record low sea ice in the northern Bering Sea and the Chukchi Sea (north of the Bering Strait between Alaska and Russia). Also very notable, sea ice VOLUME (which includes thickness of ice) has continued to suffer with 2015-17 in the top 4 for the lowest volume on record going back to 1979 (and based on decreasing of sea ice extent and thickness, likely much much longer than that). Multi-year ice…ice more than a year old…is now nearly extinct in the Arctic Ocean.

    siv_annual_max_loss_and_ice_remaining
    Arctic Sea Ice Volume since 1979. Note consistent and accelerating collapse of sea ice volume. Arctic ice volume may fall below the 2012 record at some point in the month of September in the next several years.
  3. The Arctic had its warmest year on record in 2016 and its second warmest year on record in 2017 in reliable records. The climate of the Arctic is warming to the point that permafrost is increasingly melting releasing methane and carbon dioxide, methane emissions from what are called methane hydrates (methane gas locked in water ice) are increasing from the very shallow continental shelves surrounding the Arctic Ocean and mid-latitude weather patterns are becoming altered because of reduced sea ice (more on this shortly). The Arctic tundra is also greening at an increasing rate because of rapid warming.
  4. NOAA specifically states that “the Arctic shows no signs of returning to a reliably frozen region of recent decades” because of continued climate change related warming.

Discussion – Leaving the Ice Age Era:

One thing that we must remember about the sea ice of the Arctic Ocean (and the Southern Ocean around Antarctica) is that sea ice is a product of Ice Age eras. Our planet has had a tendency historically to flip between two global climate equilibrium states with dramatically different regional weather and seasonal patterns. The Ice Ages and the Hot House “Jurrasic Park” climates have been the two long-term dominating climate regimes in Earth’s history. One characterized by huge ice sheets and low sea levels, the other characterized by no ice sheets, no sea ice and high sea levels. Human civilization has flourished in the latest interglacial period in the Ice Age era because the climate has remained largely stable for roughly 10,000 years (-1 to +0.5 degrees C relative to mid-20th century climate) and mild enough to for extensive agriculture and settlements.

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Estimated temperature of Planet Earth from 550 million years ago to the end of the 20th century.

But now, because of Anthropogenic Global Warming (AGW) from climate change, we are leaving that stability in the geologic blink of an eye.

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Projected rise in global temperature of 4 degrees C/8 degrees F (relative to mid-20th century) during the 21st century relative to the past 10,000 years.

Probably the most important regulars of climate during Interglacials are the “refrigerators” of the north and south…the Arctic Ocean sea ice and Antarctic Ice Sheet (also Greenland Ice Sheet). However, as temperatures warm because of human carbon dioxide emissions trapping heat in the global climate system, that heat warms the atmosphere and ocean, attacking the sea ice by providing excess latent heat of melting. For the Arctic, this reduces the sea ice extent and volume decade after decade. Eventually, it will get to a point, where sea ice will become so thin and tenuous, it will undergo collapse to what has been called a “blue ocean” event with 1,000,000 sq km or less ice at a minimum in September (2012 extent minimum record was 3.41 million sq km). The 2016 and 2017 extent minimums were in the top 10 with 4.14 and 4.64 million sq km, 2nd and 8th respectively. 8 of the top 10 warm season minimum extents (in km) have occurred since 2010 in the now 39 year record. The Arctic Ocean and lower atmosphere are warming and becoming more like the high latitude North Atlantic. Eventually sea ice is expected to disappear completely in the warm season in the Arctic. Some climate scientists have suggested over the past several years that the “blue ocean” event resulting from a collapse of sea ice extent could occur between 2015-2020 or so as multi-year ice has nearly gone extinct, leaving thin ice vulnerable to quick melting and battering waves from cyclones. Computer models have been terrible at dealing with the end of sea ice in the Arctic, suggesting it would stick around into the second half of this century.

Discussion – Weather and Climate Implications:

So why does loss of sea ice matter? Sea ice regulates the climate of the world in multiple ways. It acts as large white surface which reflects most of the shortwave solar radiation from the sun (high albedo). As a result, it keeps the Arctic and Northern Hemisphere (and world) cooler than otherwise. It’s wide physical presence means heat entering the Arctic Ocean goes into melting the ice in the warm season (latent heat of melting; heat goes into phase change of water from solid to liquid) instead of heating the ocean and atmosphere dramatically (sensible heat to change temperature). Losing sea ice ends its presence as a climate regulator, allowing for more abrupt warming of the atmosphere-ocean system and increasing moisture content in the atmosphere (water vapor is an additional greenhouse gas; and increased clouds may reflect some radiation, but also can limit cooling in darkness). In addition, the Arctic Ocean will warm as it is a dark surface (low albedo). Increasing ocean warming in the marginal seas of the Arctic Ocean is already leading to increased methane emissions from the shallow continental shelves (as subsea permafrost thaw the clathrates) and more rapid warming will lead to an increase in emissions of methane and carbon dioxide from land permafrost (see discussion by Arctic climate scientist Dr. Peter Wadhams of Cambridge University on YouTube). Methane is over 100 times more powerful greenhouse gas than carbon dioxide on a timescale of several years (it dissipates far faster in the atmosphere, but sudden releases can increase warming quickly). And all of these feedbacks will much more quickly destroy the sea ice extent through further warming for a longer period in the warm season until ice disappears completely.

Increased warming of the Arctic also has impacts on mid-latitude weather. There has been research suggesting that the jet stream can be strongly influenced by Arctic warming and sea ice extent (see discussion by Dr. Jennifer Francis on YouTube). This can include a weakening of the upper-level jet stream which depends on the temperature difference between the upper-level mid-latitudes and polar atmosphere (known in meteorology as “baroclinic instability”). This weakening can lead to the jet stream developing high-amplitude waves more frequently, allowing for powerful upper-level ridges of high pressure to develop and cause blocking of the progressive westerly flow. This blocking can cause more frequent stagnant weather for locations, developing droughts in some areas through prolonged dryness, long periods of heavy precipitation in other regions as well as places of very abnormally warm temps (greater extreme summer heat) vs. colder temperatures (but the warmth always significantly outpaces the cold). Increased warming of the atmosphere in general also increases rainfall rates. In addition, paradoxically, while parts of the mid-latitudes may go through below normal temps and cold weather, the powerful ridging can produce extremely abnormally warm temperatures over the Arctic regions, intensifying the warming of the far north.

An identical pattern to this has largely set up over the Northern Hemisphere November into December.

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Powerful high-amplitude ridges over the Eastern Pacific and North Atlantic. Pattern relatively stagnant at this time.
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Reanalysis of the average temperature of Earth and specified regions over the last 30 days (1981-2010 baseline…add 0.7 C to compare to late 19th century). Note extensive, persistent anomalous warmth of the Arctic.

These effects may overall lead to more abrupt warming of the world as a whole as well as (more importantly) changes in rainfall and snowfall patterns, relevant for crops and food security from increasing summer extremes (heat stress and heavy rainfall) and water resources (snow pack, groundwater, etc). Also relevant for forest health (destruction by increasing wildfires as well as bug infestations killing hundreds of millions of trees in the Western US). And a running theme in stories on climate change recently? “Faster than expected” or “Faster than previously thought”. The importance of Arctic sea ice cannot be overstated and, unfortunately, this major tipping point…which I would consider a “keystone” tipping point because of what effects it can have down the line on other parts of the climate system…seems to be on the brink. It has been 2.6 million years since significant sea ice did not regularly exist in the warm season in the Arctic Ocean.

The statistics of weather has already changed significantly because of global warming with far more extreme heat events, drought periods and heavy precipitation events than in the mid-20th century (see presentation by Dr. Aaron Thierry on shift to more extreme weather conditions; starts 12:30 min, recommend watching through 20:30 min; also see discussion of climate change on increasing extreme events by Dr. Stefan Rahmstorf). Going past tipping points far earlier than expected by climate models will increase the likelihood for far more extreme weather events as weather patterns and circulations change (in some cases difficult to predict ways). Clearly, the world still needs adequate mitigation and adaptation measures to deal with these rapid and possibly abrupt changes.

For more info into how climate change influenced global extreme weather events in 2016, see the latest report (issued today) by the American Meteorological Society with attribution studies on last year’s significant events.

–Meteorologist Nick Humphrey

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Opinion: Climate Change Communication

 

I may, perhaps, be providing a less popular view or one which isn’t the “flavor of the week”. But I’ve been hearing a lot of people recently in science discussing the communication of climate change. There has much criticism of how some have chosen to communicate. Examples: Statements considered “dire”; assuming moral or intellectual superiority if someone disagrees with the most sound parts  of the science; being condescending, etc.

First off…I do agree with the idea that people need to treat people right and fair. Do not treat people like they are less than you or unnecessarily scare them into submission. We need to communicate what we know and how we understand it and listen to what people have to say.

But with that said…

The science of climate change (and it’s main mechanism…global warming) has been gaining scientific ground since the 1970s. The understanding of the greenhouse effect and carbon dioxide goes back to the mid-1800s. I was born in 1984. Climate scientist James Hansen went before Congress in 1988 to give the realities of what climate change means. The Intergovernmental Panel on Climate Change of the UN was formed in 1988. It’s 2017. The climate of Earth has warmed dramatically since then and as a result we are witnessing impacts on our world from more extreme meteorological and climatological events, extinction rates 1000 times higher because of humans with a possible mass extinction event underway in the biosphere and millions around the world and increasingly direct impacts on human health. Meanwhile too many deny what is happening because data isn’t enough. And in many cases, many of the people we are trying to convince are not only disinterested in learning, but have a sharp anti-intellectual bent based on politics or even religion. I have no problem with people being politically conservative or religious, but that is the reality of who most of the “deniers” are. So are we not supposed to call out people who are grossly thinking irrationally or being outright deniers (not skeptics, skeptics can be convinced) in order to protect their feelings and “hopefully” convince them we are correct? Climate scientists are routinely attacked by denier politicians and on social media and their reputations dragged through the mud. Hell, even threatened. Who speaks up for the integrity of the science and scientists while we all sit around trying to be nice and protect the feelings of people who are not interested in what we have to say, respectful or not?

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Southern California Wildfires in Dec. 2017.

I guess the reason I’m rather sharp about this is because I think Americans largely discuss this topic from a position of privilege. In America, climate change is still a joke for many or largely downplayed. “Look at all this snow, I guess they got 5 inches of global warming hahaha”. “I get climate change is an important issue, but do people really think it’s as important as [insert political issue here]”. And other various statements. I think there are two issues at work here.

A woman wades through a flooded village in the eastern state of Bihar
Extreme river flooding in Bihar, India in August 2017.
  1. In the US, we are dealing with the impacts of climate change, but we (generally) still have the resiliency to face what’s happening. In the developing world, this is not the case. There have already been significant increases in extreme events relative to the mid-20th century (droughts, fires, heavy precipitation leading to issues such as increased property destruction, even more importantly, crop failures putting more people at risk of undernourishment). And in some places, there’s sea level rise becoming a problem. In the developing world, this is not a game, or a joke or something to be denied. It’s in their face. Even if individual event/event types can’t be conclusively attributed to climate change, understanding climate change is a *systemic* process of our climate heat engine, adding more energy can cause more extremes across many categories. How much to developing nations realize these growing extremes? They’ve realized it enough to basically demand the industrialized nations who have caused a vast majority of the warming of Earth via 20th century emissions, to work to limit warming to as low as possible and pay for their mitigation measures. Unfortunately, they are largely ignored because their countries are small and not economically influential enough (Paris Agreement basically is business-as-usual lite), so the world is failing and they will suffer the worst impacts of global failure first.
  2. Climate change is to outright deniers “something that’s always happening” or even to many of those who understand the basic science a more significant concern of the future. 2100 comes up a lot. Or perhaps “We have 10 years” which was since the late 1980s. How many times can we have 10 years to seriously discuss these problems? Climate change is happening now and changes *are* going to accelerate and be abrupt as we move forward. How can we discuss these issues if too many people think they know better than a PhD with 30 years of research experience? If the PhDer asserts in a blunt manner that they know better, we might think that’s intellectual superiority and unfair assumption as we all have different experiences beyond education. And technically that’s true…but if one is degrading someone because they are educated and they trust what they see over data, can we call it what it is? Anti-intellectualism and in some cases even moral superiority as it may be based on religion or politics is just as bad if not worse to our society than anything. This is clearly something anyone can be out of line on.
  3. Us “intellectuals” seem to be having debates about how to best communicate climate change. We should talk about the worse case scenarios, should be have lots of hope and solutions, this and that. My view? Tell the truth! How can we do anything about climate change if people do not actually have an appreciation of what we are facing in terms of how it can directly harm human society and our biosphere? I’ve noted that even many outside of climate science do not fully appreciate what is happening now and how bad it could be. The “worse-case” is not…it is the path we are on in all of its unpleasantness unless we make the necessary changes needed. Every time I hear “stop being alarmist” I hear “don’t tell the truth”. It’s not being alarmist to discuss alarming things. This used to be an issue in meteorology. The US didn’t used to issue tornado warnings for fear of causing panic and freezing people up. Well, they didn’t know what was coming and were target practice for tornadoes smashing their towns. Yes, provide actionable info. “Go here to learn more”, “Vote for politicians who care about you and your children’s health and prosperity”…connect climate change’s shift to more extreme conditions to extremes which have already occurred and discuss how they will become normal as new extremes appear. “Yes we’ve always had droughts, but these droughts will come in more rapid succession, which is why we must have mitigation policies to prevent this from happening”. Tell people how these changes are already happening. Give people options how to act, but be real, otherwise, why should they be concerned about the issue? Especially when we as scientists get more bogged down about how everything supposedly gets attributed to climate change vs. simply providing a strong message about the seriousness of the situation, especially NOW, not just the future.
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Carbon Dioxide concentration history over 800,000 years.

Respect goes both ways and if I’m going to respect the views of someone who doesn’t automatically agree with the science, I expect that person to respect my views and intelligence. Otherwise, I won’t trash that person, but I will move on. Some (and perhaps most) people are NOT looking to be convinced. And that’s something science communicators have to face. Not just trying to respectful, but also respecting yourself and not allowing lack of openness, compromise or cognitive dissonance stand in your way to providing knowledge. I’ve learned this from my experience as a meteorologist who are used as target practice all the time for supposedly being wrong 50% of the time (we are quite accurate), or anger over warnings (which have saved thousands of lives over decades). Climate change communicators should be respectful, be blunt, say things the way it is (consensus and personal scientific view), but not afraid to respectfully point out incorrect views and statements they KNOW are wrong and not afraid to move on if someone doesn’t want to listen. Most people will or will not figure it out on their own time, anyways.

emission-scenarios
Carbon Dioxide emissions scenarios and projected temperatures based on climate models. The world is on the business-as-usual path-RCP 8.5 for global average temperature near 4.5 degrees C/8.1 degrees F. The Paris Agreement would likely yield a temperature by end of century of over 3 degrees C average/5.4 degrees F globally. But nasty impacts are already happening now with temp near 1.2 degrees C/2.2 degrees F.

Oh and more thing. If you don’t regularly even attempt to communicate climate change to people, don’t lecture others on how they should do it. I particularly don’t want to hear the “Now is not the time to talk about climate change” meme. I discuss these issues to people whenever I can and have encountered this criticism. If you have a problem with how its done, do it and do it better. It’s actually one of my motivations for creating this site. People who care about these issues care about the seriousness of it and the people and animals it is and will harm further. Trust me, communication is even more challenging than you believed and chances are you do not understand just how serious it is even if you think you do or even some of the latest science, which is evolving rapidly. The focus needs to be on helping the citizenry be educated on these issues so we have a healthy planet as well as defending our integrity from those who would diminish our importance in informing society.

–Meteorologist Nick Humphrey

(pictured at the top is a version of the famous “hockey stick” temperature curve by Mann 1999).

Thomas Fire in Southern CA becomes 5th largest in state history; 230,000 acres and growing

The Thomas Fire of Ventura and Santa Barbara Counties in Southern California has now become (as of Sunday Night) the 5th largest fire in California State history. And based on trends and fire weather expected, it may go for the state record (273,246 acres).  After winds decreased somewhat Friday afternoon-Saturday, they picked up again on Sunday, causing extreme fire growth to an incredible 50,000 acres and reducing the containment from 15% to 10%.

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Growth of Thomas Fire since last Tuesday’s ignition.
Since the fire developed last early-morning Tuesday, it has exhibited extreme fire behavior in intense Santa Ana winds with gusts of 45-80 mph, fanning flames and, more importantly, embers far downwind of the actual fire. Currently, 790 structures have been destroyed with the evacuation of over 88,000 people. A 70 year old woman died after being overtaken by the fire following suffering severe injuries in a car crash. In San Diego County, another woman was badly burned over 50% of her body in the Lilac Fire while helping horses escape from a thoroughbred training facility.  And speaking of horses…46 horses were confirmed killed at San Luis Rey Downs where the trainer was badly injured. The death toll will likely rise among the horses as 450 horses were there when the fire rapidly struck. Many burned to death refusing to leave their stables or running back into them, while others died from shock even after initially safely away from the fire’s path. Meanwhile, another 29 horses suffered a similar fate at a ranch in Los Angeles County’s Creek Fire.

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Dry or low precipitation conditions expected in mid-range computer models (this forecast depiction by the Global Forecast System; GFS) for much the Southwest US and Great Plains through December 20th.

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Forecast upper-atmospheric wave pattern valid noon CST Monday by the GFS. Powerful ridge of high pressure over the West will continue dry, very abnormally mild conditions while colder weather remains over the eastern US.
Unfortunately, high fire danger will continue through Monday with gusts over 45 mph allowing the Thomas Fire and any other fires which develop to easily spread and do so rapidly. Conditions should relax Monday night before possible re-intensification on Tuesday. As mentioned, the Thomas Fire may reach record territory tomorrow based on trends. And as of now, NO significant measurable rainfall is expected in California (or much of the Southwest US and Great Plains) the next 10 days. A blocking upper-atmospheric high pressure pattern over the Eastern Pacific will certainly allow for intensification of drought conditions and continued dryness and moderate to high fire danger for days to come. I should also note, fire danger will also be elevated on parts of the High Plains. Much of Eastern Colorado into Western Kansas are under red flag warnings for Monday because of expected elevated breezy conditions and low humidity with dry fuels.

—Meteorologist Nick Humphrey

Extreme Fire Weather Event underway as over 100,000 acres burn across Southern CA

A few months ago, it was Wine Country, this week it is Southern California. Powerful Santa Ana winds…with gusts up to 80 mph… are creating conditions favorable for explosive fire development and extreme fire behavior. Multiple fires have already broken out across Southern California leading to the destruction of (likely) hundreds of structures in what is usually the early part of the dry season in the region.

The largest fire…the Thomas Fire…has now burned an incredible 96,000 acres since early Tuesday morning! An area equivalent to 150 square mi/241 square km. Over 116,000 acres total have been burned in total across Los Angeles and Ventura Counties, with over 200,000 people ordered to evacuate.

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Wildfire near 405 Freeway. (Fox News)
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A wind-driven brush fire was burning out-of-control in the Santa Paula area on Dec. 4, 2017. (KTLA)

Very powerful Santa Ana winds…easterly winds blowing down the Santa Ana Mountains of Southern California are driving these highly destructive fires. A strong ridge of high pressure sitting over western North America…locked in place by a highly amplified atmospheric wave pattern…is causing enhanced surface pressures over the Interior West. This elevated, dense, high pressure air is sinking rapidly down the mountainous terrain towards lower pressure out at sea causing the powerful downsloping and gap winds…the Santa Anas…which through Friday morning may produce gusts near 80 mph fanning fires. And because the air flow undergoes “adiabatic heating” as it sinks to lower elevations and compresses under higher atmospheric pressure near sea level, the temperature of the air both warms and dries *significantly* drying fuels as the high wind speeds fan the flames over those fuels.

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Southern California terrain.
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4 am PST December 7th atmospheric sounding over San Diego, CA showing *extremely* dry atmosphere over the area produced by strong high pressure system and very dry, warm winds blowing off terrain in near surface environment.

The blocking upper-air pattern favoring these unusually warm, dry conditions out west (with unusually cool conditions in the Eastern US) will continue into next week unfortunately. While fire weather conditions will vary (mild improvement as far as winds and humidity this weekend), no significant rainfall is expected during the period for Southern California…in what should be their wet season.

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Warm colors display strong upper-level ridging of the jet stream over the Western US and Canada with well above normal temperatures and helping to produce the extreme fire weather conditions in Southern California.
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The Global Forecast System (US) Model forecasts continued blocking pattern over the Eastern Pacific with strong ridging over the Western US (with some fluctuations). This pattern suggests low precipitation and continued problems with fire weather conditions into next week.
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GFS Model shows no measurable precipitation over most of the Western US during the next 10 days. Only Western Canada and Western Washington.

Current research suggests that California’s increasing shift toward more drought conditions (which can fuel and extend wildfire seasons) is being caused by the reduction in sea ice in the Arctic (a symptom of human-induced climate change). As a side note, the Arctic is experiencing extremely abnormal temperatures this November and early December, with temperatures up to 30-50 degrees F above normal in some locations and top 2 or 3 record low sea ice extent for this time of year over the Arctic Ocean (record low in the Chukchi Sea and Bering Sea).

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Major fires breaking out in Southern California


Explosive fires breaking out in Southern California right now. It’s usually the wet season by December but no rain in sight this week. Santa Ana winds instead are spreading violent wildfires which have destroyed dozens of structures and threatening thousands more. One person has died thus far. No relief expected this week as strong high pressure builds over the Western US (coinciding with the deep trough over the East).


Speaking of which, the weather has finally turned colder after very abnormally warm temps on the Plains. Traveling with my fiancé and son today to Minnesota from Nebraska to look for a new place to live. We are moving to St. Cloud January 1st so we can be closer to my family in nearby Minneapolis and I will start a second masters at St. Cloud State. Highs in Eastern Nebraska will be largely near normal today (near 40) before turning colder the rest of the work week. Central MN will see similar departures below normal…after much of the region had huge departures above normal (over 20 degrees in many cases) for days. A general pattern seen for much of the country in the month of November.

—Meteorologist Nick Humphrey

Very above normal temperatures dominating US to end November

Much above normal temperatures are dominating much of the United States right now. This is largely a product of a zonal or progressive jet stream moving along the northern tier states and southern Canada locking colder air over interior Canada and the Arctic (although, I note, the Arctic is seeing much above normal temperatures relative to what they should be seeing as well!).

My area…Eastern Nebraska…has been seeing many days of 60s and even mid-70s, including today. The average temperatures this time of year should be in the low to mid-40s for highs and near 20 for lows. Instead it’s been feeling like it’s around birthday time for me. My birthday is in May.

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Global Forecast System model analysis of surface air temperature anomalies for November 27th. The GFS tends to have a minor warm bias from reality, but it is accurate is showing significant above normal temps over the western and central sections of the United States. The baseline normal period is 1979-2000, prior to the significant amplification of climatic warming in the Arctic (occurring because of anthropogenic global warming).
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Global Forecast System model forecast depiction of upper-air wave pattern at 250 millibars (~10,200 meters/33,500 ft) valid Wednesday morning. The jet stream will remain largely over the northern tier and southern Canada this week with above normal temps of varying departures over the US.

As we move into the first week of December, trends point to some dip in the jet stream over the Western US early next week causing below normal temperatures. However, this will also amplify the jet stream over the eastern two-thirds, producing significantly above normal temperatures yet again.

One additional thing of note. Snow cover is virtually non-existent in the contiguous US today (Nov. 27th). Only 4% of the CONUS has snow cover today. Going back to 2003, this is lowest snow cover extent for this particular date. The second and third lowest for Nov. 27th were 8.7% (2009) and 10.2% (2011). The snow cover area extents on Nov. 27th in 2010, 2012-2015 were in the range of 20-35%. 2016 was fairly low at 15.4%. The data is available HERE.

nsm_depth_2017112705_National
Snow depth analysis map for the US and southern Canada for November 27, 2017.

I don’t know date prior to 2003, however it is known that climate change is reducing snow cover extent and depth in the US and the Northern Hemisphere beyond natural variability. The aforementioned trough in the West should increase that extent somewhat next week.