The sun shines on the middle of the continent while the coasts face the wrath of ocean storms

Quite the day out in weather world, although you wouldn’t know it from looking outside here in the land of the corn. Beautiful day, although still waiting for the leaves to make an appearance. Soon enough, but the sun shines bright overhead. Calming and peaceful for a walk later.

Outside my favorite coffee shop in Lincoln. 52 degrees F and very light wind. Your normal late March day in all its glory.

After a winter which was tumultuous with big temperature swings (sometimes 50 degrees F within days), it’s nice to have a little stability for some days. Looking near or mildly above normal temperatures the next several days with periods of rain showers. Our winter in this region was less than 0.5 C below normal relative to 1981-2010, but running 0.5-1 C above normal relative to 1881-1910 when factoring the effect of climate change. And temperatures from anthropogenic climate change began rising globally after the mid-1700s, so late-19th century values are still conservative on the changes which have occurred here. People around here were complaining about how cold it was this winter. It could’ve been a lot worse as we had a few 60 and 70 degree temperatures in February mixed with the 10s and 20s for highs in January and February! Just wild.


Global temps relative to the late-20th century vs. the late-19th century (the latter showing the effect of anthropogenic climate change very obvious). The Arctic is getting “hot” (for the survival of sea ice) fast with major effects on the region and world for further global warming.

Actually reminds me of a story in the coffee shop of a mother and adult daughter discussing this past winter. The daughter saying how “normal” it was to have these huge swings in temperature and crazy weather (snow then short-sleeve weather). Mother saying “Well I remember when I was young, it would be more consistently cold with a lot more snow, not like now”. What’s normal has changed with time in a lot of world, but you wouldn’t know it unless the different generations notice and chit chat about it.

Our chances of snow appear to be over. Never say never, as the East Coast seems to be getting blasted by these cold storms, but when you start seeing these consistent mild conditions finally, it’s usually a sign of the seasonal transition…finally.

I do have some concern over this Spring’s tornado season I must say. La Nina periods in the El Nino Southern Oscillation tend to be known for quite intense tornado outbreaks. Trying to get a science paper reading in about it this week if I can. The Gulf of Mexico waters are running above normal for moisture, the South has been quite warm overall with record warm days and months this winter. And jet stream dynamics continue to be favorable for bringing periodic shear profiles for significant severe weather. The atmosphere put on quite a show this weekend in the Deep South where it is climatologically favorable for tornado activity. Reminds me to prep an emergency kit. We do have a weather radio, but with things like tornadoes and urban flooding, you never know when you will need a little more to get through a few days of darkness and no refrigeration.

While, it’s quiet here, the West and East Coasts are being battered by major winter storms to start Spring. Very strong upper-level trough over the eastern third of the country and another over the Eastern Pacific means the 4th nor’easter of the month in the East and huge atmospheric river event in Southern California. Heavy snow or flooding/mudslides?

Middle atmosphere wave pattern showing deep trough generating significant coastal storm with snow over the mid-Atlantic/Northeast. Atmospheric river from SW flow over California.
Strong east coast storm. You can also see how dead quiet it is over the center of country from prominent high pressure overhead.
Moderate to heavy snow falling over New Jersey and New York City/Long Island.
Strong West Coast storm impacting California with heavy rain.
Moderate to heavy rainfall impacting parts of Southern California. Problems with flooding and mudslides/debris flows likely. (radar as of 1 pm PDT).

Good mid-week to all and stay safe in these stormy areas!

–Meteorologist Nick Humphrey


High Amplitude Jet Stream Pattern To Lead to Extremely Abnormal Temps for Central/Eastern US; “Blow Torch” Heat to Arctic.

The US will be a land of extremes as a high amplitude jet stream…the story of this winter continues to impact the US as very abnormally cold temperatures impact the Central US and (later) the Great Lakes region, with very abnormal heat spreading northward into the Eastern third of the country mid-week. Sunday, much of the Great Plains were experiencing temperatures 20-25 degrees F above normal (~10-12 degrees C). As the week progresses, the jet stream amplitude over North America will intensify and bring highs of 30 degrees F (15+ C) or greater above normal mid-week to the Ohio and Tennessee Valleys into the mid-Atlantic and New England states. This means mid-Spring highs on the East Coast and a resumption of well below freezing temps over the Central and Northern Plains.

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In addition to the abnormal temperatures, another major story will be potentially heavy rainfall across a wide swath of the Midwest and Deep South ahead of the accompanying cold front which will push eastward mid-week. Abundant moisture from the Gulf of Mexico will aid in the generation of rainfall, some of which will help short term drought conditions, but could also produce flash flooding.

Moderate risk of flash flooding over portion of Texas, Oklahoma, much of Arkansas and southern Missouri Tuesday.
Tuesday evening forecast surface map showing widespread moderate to heavy rainfall likely from Texas to Michigan.

The Arctic Ocean has been experiencing an extraordinarily warm winter with consistent high heat to the region (relative to regional norms). As a result, sea ice has been suffering severely as the combination of high amplitude high pressure ridging and ocean cyclones push heat, wave action and wind into the sea ice sheet, along with very abnormal sea surface temperature right up against the sea ice (9-18 degrees F/5-10 degrees C above normal). Sea ice extent is currently running at the lowest on record in the history of human civilization, rapid melting already in progress in the northern Bering Sea, and 2017 annual sea ice volume was the lowest on record. The current max extent this season occurred on February 6th. The current earliest maximum peak extent is February 25th in 2015. The current record year for record minimum peak extent is 2017…2018 is currently beating that record and has the 2nd lowest year-to-date volume as well.


The sea ice is showing some signs of refreezing after its early February peak. However, more extreme heat is to come as more storms from both the Bering Sea and the North Atlantic advance heat and moisture into the Arctic Ocean this week. One storm will move over far Eastern Siberia and into the Chukchi Sea on Tuesday. Wednesday, another, stronger storm will approach Greenland, moving over the Canadian Archipelago Thursday, slowly shifting toward the Beaufort Sea Friday.


Note the last two sea level pressure images for 2/23 and 2/24. Not only the strength of the cyclone (in blue) but the tightly packed lines of equal pressure (isobars) between the low pressure system and the strong high pressure system over the Barents Sea, north of Scandinavia. These tightly packed isobars represent a very strong pressure gradient which will result in very strong southerly wind gusts (near hurricane-force) and intense wave action striking the sea ice sheet of the Arctic Ocean mid to late week. This in combination with the very warm, moist air moving into the region will make for a “blow torch” of heat from the Atlantic, eroding the cold conditions of the Arctic, stunting the freeze season further. This will likely lead to further ceasing or recession of sea ice as well.

GFS forecast high temperature for Thursday, showing above freezing temperatures penetrating into the deep Arctic. This may continue into Friday. Today through Tuesday will feature near or above freezing temperatures moving out of the Bering Sea into the southern Chukchi Sea as well.

I’ve been tracking the Arctic all season and there has been a shocking level of persistent warmth in the region with 2-3 degrees C above normal temps (for the region) being quite common many more extreme day higher than that. The Arctic Ocean basin may experience, as a region, anomalous temperatures of an incredible 6-8 degrees C above normal Tuesday-Saturday. This is relative to the 1981-2010 average. However, as climate change is abruptly warming the Arctic region, leading to rapid sea ice loss compared to the past, relative to the late 19th and mid 18th centuries (in the early era of human generated climate change), the anomalies are likely 0.7 or 1  degree C higher than that, respectively.

GFS Anomalous temperature forecasts for the Arctic region valid 00 UTC Feb 23rd. Extreme heat by regional standards over the Arctic for much of the week.

The implications for the collapse of sea ice are quite serious. The sea ice sheet regulates the jet stream by making the Arctic region permanently cold across a wide area. As long it it remains permanent with only modest seasonal melt, it can behave much like a continental ice sheet would behave on the atmosphere (like in Antarctica). The jet stream exists because the Arctic atmosphere is cold throughout the vertical column. The strong temperature gradient with the mid-latitudes is what makes it exist. But with abrupt warming of the Arctic caused by the collapsing ice sheet (which feeds back on accelerating such a collapse), this weakens the jet stream and has been causing it to become wavier with increasingly more extreme and frequent high amplitude patterns (which feedback and melt the Arctic more). Such research has been conducted by scientists such as Dr. Jennifer Francis of Rutgers University and others, showing the jet stream slowing and becoming higher in amplitude since the 1960s. Such abrupt warming also leads events such as “sudden stratospheric warming” and “splitting” of the polar vortex, supporting Arctic blasts to the south and abundant heat transport to the Arctic.

If the ice sheet collapses completely (no more in summer, low to little meaningful extent in the polar night), you get even more abrupt warming of the sea surface from below and above through collapse of the ocean thermocline (persistently cold water “cap” atop somewhat warmer water) and air temperature inversion (warmer air atop cold surface air) as well as from the much reduced albedo (white, reflective surface). The warming atmospheric column with height further reduces the temperature gradient with the mid-latitudes, weakening the jet further and causing more extreme “wave action”, greater blocking patterns as you get these big waves and little eastward progression of systems and the polar jet actually retreats farther north. This can dramatically shift precipitation patterns northward could cause much hotter, drier conditions in the mid-latitudes. It’s been a major concern for a long time in in climate change science, but a process thought to be of concern in the “high emissions” scenarios of the mid to late 21st century as increasing aridity across the mid-latitudes would destroy forests and not allow crops to be grown where they are currently grown because of increasing extreme heat (or storms). So this would have impacts not only in the Arctic, but also in the mid-latitudes. Unfortunately, a recent phrase has been increasing use the past few years. “Faster than expected”. Some prominent researchers openly admit an ice-free Arctic may be possible before 2020. See also HERE.

I’ll have more on the situation in the Arctic this week as well as the heavy rainfall in the US. Also, keep an eye on Tropical Storm Gita approaching New Zealand to start the week!

–Meteorologist Nick Humphrey

Cyclone Gita headed for close passage of Tonga

Cyclone Gita in the South Pacific is a powerful Category 4-equivalent tropical cyclone on the Saffir-Simpson Scale (as of the time of this post). Maximum sustained winds analyzed by the US Joint Typhoon Warning Center are up to 130 mph with gusts to 155 mph. Gita is moving westward and is expected to pass near or over Tonga around 12 UTC Monday (6 am CST or 1 am Tuesday local time). The storm is expected to be at least a powerful Category 4 storm. There is moderate wind shear (increasing winds with height effecting the cyclone and limiting more rapid intensification. However, with water temperatures along the path of 28-29 degrees C (82-84 degrees F) and well-organized structure, Gita will be a potentially catastrophic storm if its eye wall moves over the main island. Gita will also produce very heavy rain (perhaps 6-12 inches) which will lead to flooding. A state of emergency has been declared in the island nation.

Gita (9P) moving westward toward Tonga. Visible satellite image at 04:52 UTC Monday.
03 UTC Monday Advisory on Cyclone Gita by the Joint Typhoon Warning Center.

After 24 hours, Gita is expected to gradually weaken as sea surface temperatures cool and vertical wind shear increases as the system begins to turn to the southwest into higher latitudes. However, Gita is expected to remain a hurricane-force storm through the end of the week.

New Zealand will need to keep an eye on the remnants of Gita as the dying circulation an moisture plume may curve back southeastward in the mid-latitude westerlies. While, the forecast will certainly change somewhat…such as the position of the upper-level trough of low pressure southwest of New Zealand which will cause the system to curve back towards the country beginning Sunday…any remnant system may lead to locally heavy rainfall for both the North and South Islands early to mid-week next week.

European Model accumulated total precipitation forecast ending 00 UTC February 22nd. The remnants of Gita are forecast to curve back southeast toward New Zealand early next week delivering very rainfall.


–Meteorologist Nick Humphrey

Effect of Sun-Mon Arctic Ocean Storm on Sea Ice

You may remember I posted last Friday about the major North Atlantic storm which was expected to move into the Arctic Ocean Sunday and Monday producing hurricane-force winds, 30 ft+ waves and temperatures over 40 degrees F above normal (near or even above freezing in places). Well that storm advanced through the Arctic and now noticeable effects can be seen (via satellite analysis) on sea ice concentration (amount of ice vs. open water in a given area) and on sea ice sheet growth and resulting extent.

North Atlantic Surface Analysis valid at 06 UTC February 5th (midnight CST) showing the 958 millibar low pressure system off shore northeast Greenland entering the Arctic Ocean from the North Atlantic basin. (US National Weather Service)
Global Forecast System model analysis valid 12 UTC February 5th (6 am CST). This shows the very strong sustained winds and (by Arctic standards north of 80N) extremely warm temperatures during the height of the storm. This was thanks to very strong warm air advection from the Atlantic Ocean. The system had a sub-tropical connection with heat and moisture originating from the subtropical western Atlantic. Average temperatures in many places should be -30 to -15 F (-34 to -26 C). (

Included are two images of the sea ice concentration…one I saved from the February 3rd, another just posted for February 6th. Lighter blues are for 90-95% concentration, with yellows and reds being for 75-90%.

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Extent growth basically stopped between February 3-6 (near 13,300,000 sq km for four days).

2018 year-to-date extent (currently at record lows) vs 2016 extent (previous daily record lows for this time of year) and the 1980s average. Sea ice extent and volume collapse is underway in the Arctic Ocean because of Anthropogenic Climate Change caused by abrupt warming in the Arctic (notable since the 1980s, accelerating since the 2000s). 

More very above normal temperatures will hit the Arctic this weekend as a powerful blocking high pressure system over the Pacific (sound familiar…) raises temps once again across Alaska and allows storm tracks to head for the Bering Strait and Chukchi Sea once again. Meanwhile, the Atlantic side will continue to remain “open” with another storm also moving into the region this weekend. No storm appears to be nearly as powerful as the Sunday-Monday event, but the litany of systems bringing at least some wind, wave action and temps not far below the freezing point of salt water is no good for the Arctic.

Temperature anomaly (degrees above or below average) forecast by the GFS model for the Arctic region valid 18 UTC February 10th (noon CST). Normal is based on 1981-2010 baseline. To approximate the major effect of anthropogenic climate change since the end of the 18th century add +0.9 degrees C (K).
GFS maximum temperature forecast valid 18 UTC February 10th (noon CST). Very warm air temperatures on both the Atlantic and Pacific entrances to the Arctic Ocean.

Arctic sea ice is extremely important for everything from Arctic regional ecology, marine biology to effects on overall warming of the Arctic Ocean and surrounding land areas (and permafrost). There is also evidence that the rapid warming of the Arctic because of anthropogenic climate change is altering the polar jet stream circulation which may be leading to an increased frequency and magnitude of extreme weather events. 

Sea ice thickness and thickness anomalies in January 2018. (Zach Labe)

–Meteorologist Nick Humphrey



Meteorological Analysis of January 22, 2017 Great Plains/Midwest Blizzard As It Happened

Here is a meteorological analysis I did on Monday of the blizzard which raked much of the Central Plains and upper Midwest from Nebraska and Kansas to Minnesota and Wisconsin with heavy snow and high winds. It was recorded around 11:30 am CST Monday. Those who follow me on my Facebook page (also see my feed on the sidebar) were able to see it right after it was uploaded, but I’m posting it here for those interested in hearing me discuss the event as it happened. Peak snow totals up to a foot and a half resulted in parts of Nebraska, Iowa and Minnesota. Lincoln and surrounding parts of the town only saw 2-3 inches but the totals increased dramatically not far west and north. We got off easy compared to the one foot and greater totals in northeast Nebraska. Winds gusts throughout the region peaked 45-60 mph. You can hear the noise of the high wind through my door in the video.

By the way, my son Bruce makes a guest appearance as he tries to turn off my computer while recording. Haha.

The Science Behind “Atmospheric Bomb” Cyclones

The first full week of January featured a powerful winter storm – known as a nor’easter – intensify off the east coast of the United States causing snowfall from the North Florida to Maine into Atlantic Canada, along with widespread power outages from strong winds as well as storm surge flooding and battering waves.

Powerful nor’easter offshore Long Island Thursday afternoon.
Vehicles navigate Monument Square on Sunday in North Adams, Massachusetts, which was under a snow emergency. Gillian Jones / AP

The storm underwent rapid intensification known in meteorological slang as “bombogenesis”. An “atmospheric bomb” occurs when a developing cyclone’s low pressure center intensifies explosively…defined as at least 1 millibar or 1 hectopascal drop per hour on average during a 24 hr period. This system had a pressure drop of 54 millibars in 24 hrs (1004 to 950 millibars). This bombogenesis phase can occur in both frontal cyclones seen in the mid-latitudes such as with this week’s storm or with tropical cyclones. A famous example would be Hurricane Patricia in the Eastern Pacific in 2015 which experienced a minimum central pressure drop of 95 millibars during a 24 hr period (967 to 872 millibars).


Bombogenesis in mid-latitude cyclones occurs when there are favorable jet stream dynamics which allow for strong vertical motion, to force air up and away from a developing surface low. These include very strong upper-level winds and diverging flow. This allows for a high rate of decrease in surface pressure, intensifies the pressure gradients, reinforces the “conveyor belts” of warm, moist air flowing into the cyclone for clouds, releases latent heat and producing precipitation, which further strengthens the storm.


For frontal cyclones, the most intense atmospheric “bombs” occur when you have a merging or “phasing” of the northern and southern jet streams (basically the polar jet with much colder air to its north and the subtropical jet with far richer moisture sources to its south). This “phasing” of jet streams occurred with the most recent nor’easter.

Upper-atmospheric air flow maps from Wed-Thurs morning showing the phasing of the polar and sub-tropical branches of the jet stream, which intensified the massive East Coast nor’easter.


“Bomb” cyclones are nothing new. Unfortunately for us who have to live and deal with their impacts, human-induced climate change has forced our world to retain a significant amount of heat energy. These major changes on climate in just the past 20-30 years have caused statistical changes in observed weather. And one of those changes is in rapid intensification of cyclones. With tropical cyclones, there is evidence that a warming ocean and lower atmosphere (with greater moisture/latent heat release) is playing a role in increasing the frequency of rapidly intensifying tropical cyclones (here’s a paper by Kishtawal et al. on the topic). With mid-latitude cyclones, there is ongoing debate on the issue. However, there ongoing research suggests that in addition to thermodynamic roles, the increasing “waviness” of the polar jet stream theorized to occur in a warming world may have impacts on mid-latitude weather and long-term climate patterns. High amplitude jet streams produce greater mixing of air masses at lower levels of the atmosphere between the polar regions and sub-tropics (a process known as temperature advection). The increase in jet stream amplitude acts as a feedback to further amplify Arctic warming rapidly relative to the mid-latitudes as much warmer air advects into the far north (jet slows slightly with less temperature gradient, but becomes much more amplified, enhancing warming further). While the effect of the mid-latitudes circulation patterns on the Arctic seems more well-established because of the rapid changes in the far north, climate scientists are in much higher disagreement on the effects of feedbacks back on the mid-latitudes. Dr. Jennifer Francis (Rutgers University; see short webinar on possible connection between Arctic warming and mid-latitude extreme weather), among other scientists continue to do research actively on jet stream dynamics in the mid-latitudes with regards to climate change. But such a combination of warming energy sources and amplified jet stream patterns could further the development “bomb” cyclones in the future as the world continues to warm, at least while there remains strong temperature gradients between air masses to fuel mid-latitude storms (mid-latitude cyclones may be weaker and/or found much farther north in a much warmer planet). And there has already been a statistically detectable shift northward in winter storm tracks in the Northern Hemisphere and an increase in the severity (intensity of cyclones and precipitation rates) and frequency of “atmospheric river” events in the Eastern Pacific toward North America since the 1950s (see Key Finding #4-5/Chapter 9 of US Climate Report).

What “bomb” means as far as hazardous impacts will depend on the specific storm, but when it comes to ocean storms, like what was witnessed this week, obviously, damaging winds, heavy surf, storm surge flooding and heavy precipitation which can cause dangerous disruptions are what are all possible. In this case, much of it was all snow and ice. In the warm season, it can be flooding rainfall. But human-induced forcing (retaining of heat in Earth’s system) is now known to play a role in the attribution of the intensification of these large-scale weather systems within the changing climate regime.

–Meteorologist Nick Humphrey

Multiple Arctic Air Surges Expected Into Next Week

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.

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European model model depiction of morning temperatures over the US and southern Canada at 6 am CST Tuesday 12/26. May be colder with winds.
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.

US Global Forecast System model forecast for 6 pm CST Thursday 12/21 showing highly amplified wave pattern of atmosphere at 500 millibar pressure surface (approximately 18,000 ft altitude).

“HOT” Arctic. Temperatures in Barrow, AK running over 30 degrees F above normal on Thursday (normal high is -3 F). Normal low is -15 F. That abnormal warmth will become less intense, but persist into next week.
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.

European model forecast accumulated precipitation through 12/30 showing the possibility of little to no measurable rain or snowfall in much of the Southwest US. Been little to be had in that region in December.
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