–Meteorologist Nick Humphrey
–Meteorologist Nick Humphrey
This winter has been a fascinating one to say the least. Wild oscillations between very abnormally warm and very abnormally cold while other places are are just consistently very warm. Or perhaps just very dry. Much of this has been thanks to the current La Nina pattern in place over the Tropical Pacific. The atmospheric pattern leading to abnormally cooler waters over the eastern tropical region also lead to the promotion of strong high pressure systems over the Central North Pacific with unusually higher amplitude jet streams. This favors a polar jet aiming for the Pacific Northwest, northern tier and into the northeastern third of the country while the Southwest and Sunbelt see drier conditions.
Of note with this pattern regime has been the, at times, extreme nature of the jet stream amplitudes. They have driven very warm temperatures into the Arctic with record low sea ice across the Arctic Ocean, the warmest December on record across the state of Alaska, and record high temperatures in portions of the Southwest US in January with the aforementioned persistent drying and intensifying drought concerns.
Meanwhile, significant Arctic intrusions have been impacting the US, particularly in January and more appear likely in February as “teleconnections”…patterns in global circulation which give clues toward a general weather regime for a region of the world…show signs of further intense extreme jet stream amplitudes with very strong upper-level high pressure systems blocking storm tracks over the north Pacific and Bering Sea, which downstream will mean a cross polar flow in the upper atmosphere of very cold air upper troughs and surface Arctic fronts and high pressure systems over northern Plains/Midwest into the Northeast US. The Deep South should escape as warmer air from the subtropics attempts to advance north and may keep the Arctic air at bay. Europe looks to also have periods of similar cold (and interior Siberia of course! Check out the incredible cold they had last month).
Powerful Arctic Ocean Storm Sunday-Tuesday
While the mid-latitudes get hit with Arctic cold, the Arctic is being pounded by significant amounts of mid-latitude heat. And now the computer models are pointing towards a major North Atlantic storm developing early this weekend, moving over Greenland and then into the middle of the Arctic Ocean Sunday night-Monday. This storm will be very powerful…as strong as any classic North Atlantic ocean winter storm, and will bring significant amounts of high winds, battering waves and high “heat” to the Arctic. How warm? Perhaps as warm as 50-60 degrees F above normal temperatures over much of the Arctic Ocean. This will mean highs near or just above freezing up to the North Pole!
This storm is forecast to initially form southwest of the tip of Greenland and east of Quebec Friday and will beginning moving over Greenland Saturday. Sunday, the system will begin to impact the Arctic, with warm and moisture transport from the North Atlantic (all the way from the Azores!) increasing abruptly late-Sunday. By Monday morning, models indicate waves moving up the Fram Strait toward the Arctic may be as high as 30 ft in strong south-southwesterly flow. Over the sea ice sheet, the low pressure system will be intense as it emerges from Greenland…possibly sub-960 millibars with widespread wind gusts of up to hurricane-force likely over much of the interior Arctic Ocean east and south of the low on the Atlantic side.
Why this storm is so significant is because the Arctic sea ice is continuing to undergo collapse because of anthropogenic climate change. If the Arctic climate warms to the point that it simply cannot support sea ice in the warm season, with the Arctic Ocean warming as a result of very low albedo (reflectivity to visible light which would otherwise limit warming) compared to white ice (or latent heat of melting/freezing, instead of heat going into warming the ocean directly), this will have dramatic effects on not only regional climate but global climate (I can go into greater details in this in the comments or provide resources). Generally this was something expected much later in the future, but may occur earlier than expected, although it is difficult to predict when exactly this will occur as it would be nonlinear and abrupt. However, as mentioned, ice volume and extent for ice are running at record or near record lows across the Arctic Basin. Some of these effects on albedo and heating have already begun to be felt over the past several years on the marginal seas which are beginning to become increasingly ice free during the warm season (Chukchi Sea, Beaufort Sea, Eastern Siberian Sea), but it’s important to not have the interior Arctic Ocean lose significant ice. Particularly in the winter, but it has been struggling just to freeze this winter! For more on recent sea ice developments see these videos by Paul Beckwith (M.Sc, PhD candidate; HERE and HERE).
In the meantime, while we have year to year variability…various teleconnection patterns, anthropogenic forcing (CO2, other gasses) is the most dominant regime on our climate and so even while I must emphasize weather is not climate…I must also emphasize that climate is a statistical distribution of weather events; and so extreme weather events which are increasing in frequency and magnitude are a sign of our climate shifting to more extreme conditions and in sensitive places (particularly cold climates like the Arctic), those shifts are incredibly noticeable.
–Meteorologist Nick Humphrey
After periods of very abnormally warm weather, surges of very cold air from the Arctic will be barreling out of Canada starting Thursday into next week.
These cold surges are a result of a highly amplified jet stream which has been shifting around North America for the past few weeks with a strong ridge over the Western US and trough over the US. However, the ridge is retreating over the Eastern Pacific and intensifying into Alaska, heating up the Arctic and putting southern Canada and the US in the ice box.
The Storm Prediction Center does have a marginal risk of severe weather ahead of this week’s major frontal system over Southeast TX Friday. The risk appears to be for a isolated severe thunderstorm wind gusts over 60 mph and low risks of tornadoes.
Here in the land of the corn? We should peak in the upper-30s tomorrow morning and then have falling temperatures and increasing winds during the afternoon with freezing drizzle with increasing breezy conditions out of the northwest. Not much snow accumulation expected here, although it could get slick from some of the freezing precipitation. Anyone else in the middle of the country, be careful as the cold air moves in if you’re on the roads!
Quick update on the Thomas Fire in California:
As of this post, the fire burned 272,000 acres…the 2nd largest in California state history (within less than 1500 acres of the state record). It has killed two people, including a firefighter. It is 60% contained. It began December 4th.
No significant rainfall is expected is expected in Southern California through the end of the month based on computer models. The Eastern Pacific ridge of high pressure seems to have a dominant grip on the region unfortunately. A combination of a La Nina pattern and climate change-induced extremely low Arctic sea ice and warm Arctic causing an incredibly amplified jet stream which tends to produce “stuck” and “stale” patterns.
We can only wait and see if the lack of rain and snow forecast in the models in fact verifies for the Southwest US.
Happy first day of (astronomical) winter!
–Meteorologist Nick Humphrey
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.
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.
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.
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.
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
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:
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.
But now, because of Anthropogenic Global Warming (AGW) from climate change, we are leaving that stability in the geologic blink of an eye.
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.
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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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.
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.
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.
It was VERY smoky in the Northwest Wednesday unfortunately because of major fires in the Interior US and Canada.
BELOW were the highs Wednesday for select cities. Southwest WA and Western OR are being particularly hit hard by this heat wave. Interior Western WA and Puget Sound were actually sparred some of the worst of the heat today by the smoke; it was thick enough to act as a cloud to dampen the radiation and limit warming in places such as Seattle. It remains to be seen if that will be the case Thursday. If not, the hottest day if the heat may very well be Thursday for Western WA (and about the same for Western OR). This, along with an Air Quality Alert in effect for much of Western WA/OR means those in the area will need to not only be careful with strenuous activity to avoid heat-related illnesses, but also avoid breathing problems, if sensitive to such smoke particulates.
(record highs in red)
Seattle (National Weather Service Office): 88
Seattle (International Airport): 91 – Old Record 89 (2009). Special Note: Seattle also shattered its daily record for warmest minimum temperature with a morning low of 69 (old record was 61 set back in 2015) and it ranks as the 2nd warmest daily minimum temperature on record.
Hoquiam: 89 – Old Record 81 (1993)
Quillayute (North WA Coast): 98 – Old Record 89 (1993). Special Note: This was likely caused by easterly downslope winds; easterly surface winds flowing along the higher hilly terrain descends down the slopes resulting in “adiabatic heating” (compression heating from increasing pressure on the air molecules as the flow drops in elevation). This hot air blows into town and shoots the temperature up fast. This process occurs throughout the region and is the reason why it is typically a “dry heat” in Western WA/OR during heat waves. The heated air becomes dry, with little moisture added to it.
Astoria: 93 – Old Record 88 (1939)
Portland (International Airport): 103 – Old Record 96 (1986)
Troutdale (East Portland Metro): 105 – Old Record 99 (1995)
Hillsboro: 105 – Old Record 99 (1939)
Salem: 107 – Old Record 102 (1939)
Eugene: 102 – Old Record 99 (1939)
Medford: 112 – Old Record 105 (1993)
Klamath Falls: 99 – Old Record 94 (1977)
As you see, for Oregon, there was a major theme in the records for Wednesday’s climate stations. It was the hottest day many of these locations had seen on this date since 1939.
Please be safe if you live in this region the next couple of days. Drink PLENTY of water, take breaks from the heat as necessary, use fans if you don’t have air conditioning (common problem in this region, I lived there without air conditioning and the summers statistically are generally getting warmer because of anthropogenic climate change…), and again, like me, I have asthma; if you don’t need to do anything strenuous outside DON’T! Just drive instead of walk or just stay inside, cool and relax. The slightly cooler weather (still above normal, however) starts Friday.