Friday, October 30, 2015

The First Flooding of The Season!

Thursday, October 29, 2015
4:59 pm

Record flooding in Mt. Rainer National Park, November 2006. Credit: National Park Service

For some reason, the weather always seems to get dramatically stormier as soon as we switch from October into November. The weather could be fine for trick-or-treating, and then whammo! November rolls around, and there are more fallen branches and puddles than you can shake a stick at.

This year, our storm season will be arriving early.

From Friday night to Saturday morning, a very juicy front will sit over our area and soak the entire state. The Southern Cascades will get particularly hard hit. This morning's National Weather Service forecast discussion called for over 15 inches in the space of two days to impact the windward slopes of Mt. Rainier. I'm not religious, but I think 15 inches of rain in 48 hours is pretty Biblical.

An ark with all the newest technological innovations! Credit: Kimmo Virtanen

This is a classic atmospheric river event. Atmospheric rivers are streams of moisture in the atmosphere that may be thousands of miles in length but less than a few hundred miles wide, and they are the events most commonly associated with flooding on our local rivers. These atmospheric rivers often occur along frontal zones where there is preexisting uplift, creating precipitation, and they often stall over an area instead of quickly brushing through. The picture below shows a massive atmospheric river stretching well west of Hawaii, and it is going to be plopped right over our area for the next 24 hours and give us a ton of rain in the process.

Valid 09:30 am PDT Fri 30 Oct 2015. Credit: UW Atmospheric Sciences

By tomorrow morning, this river will have moved a bit south, and will be positioned right over our area, giving extremely heavy rain to our region and blustery winds along the coast and on exposed peaks.

Valid 05:00 am PDT, Sat 31 Oct 2015 - 36hr Fcst. Credit: UW Atmospheric Sciences

We had a massive atmospheric river event on November 6-7, 2006, and this event caused record floods on many Cascade Rivers and caused millions of dollars of damage to Mt. Rainier National Park. While this event does not appear to be as devastating as the one we witnessed in 2006, it looks really wet. Take a look at the graphic made by the NWS below.

NWS SEW Current Weather Story

Right now, the National Weather Service forecasters up at Sandpoint are forecasting anywhere from 1-4 inches of rain in the lowlands, 4-8 inches of rain in the mountains, and 12-15+ inches of rain near Mt. Rainier. This will cause flooding on many area rivers, particularly those in the South Cascades. Thankfully, river levels are very low right now and the ground is not very saturated, so this event will not cause major flooding on our local rivers, with the exception of some rivers near Mt. Rainier, particularly the Carbon River.

The heaviest rain will arrive around 10 pm tonight and end around noon tomorrow. Trick-or-treaters may have to avoid some puddles, but they should not be trudging around in the rain tomorrow night.

By the way, after the cold front passes through at lunchtime tomorrow, snow levels will drop to 3,000-4,000 feet, and the Cascades will get significant snow. The Seattle NWS forecast discussion talked about issuing a winter storm watch from Saturday night through Sunday this afternoon, and I suspect they will do that!

Enjoy the fun weather! I'll be posting updates throughout the night on my Facebook page! And by the way, Snoqualmie Falls is absolutely stunning during these flood events. I'd highly suggest going to check it out Saturday night or Sunday morning.

Snoqualmie Falls during a major flooding event, January 7, 2009. Credit: Bdelisle

Stay dry!

Sunday, October 25, 2015

An Overview of Hurricane Patricia And Its Relationship To El Nino

Saturday, October 24, 2015
8:09 pm

Visible satellite image of Hurricane Patricia at record intensity approaching the Western Mexico Coast. Taken October 23, 2015. Credit: NASA Terra/MODIS Satellite

Patricia was the deepest cyclone ever recorded in the Western Hemisphere. Deeper than Wilma, deeper than Katrina, deeper than Camille, and far deeper than Sandy (all these storms are named after girls!). She had a central sea-level pressure of 879 hPa, beating out Wilma's 882 hPa central sea level pressure, which was the record for the Western Hemisphere at the time (and remains the record for the Atlantic Basin). These are astonishingly low pressures, and more representative of air pressure values you'd find at nearly 5,000 feet. For comparison, our August 29th summer windstorm, which knocked out power to 500,000 and killed two people, dropped to 986 hPa.

Perhaps even more impressive, however, was how quickly Patricia developed. Wilma took only 30 hours to drop from 982 hPa to 882 hPa, a 100 hPa drop. Patricia did a 100 hPa drop in 24 hours, and was nearly the fastest-developing cyclone on record. Averaged over an entire day, that's a drop of over 4 hPa an hour, and there were undoubtedly times when the rate was faster than that. For comparison, our major windstorms tend to deepen at 2-3 hPa per hour, and do not sustain that rate for very long. The only storm to ever develop faster than Hurricane Patricia was Typhoon Forrest in the Western Pacific.

But ultimately, the most impressive thing about Patricia though was her winds. Even though Patricia was an incredibly intense hurricane, Patricia wasn't all that large. Although this limited the storm surge and range of the damage, it meant that there were steeper pressure gradients within the storm, leading to higher winds. Patricia was estimated to have sustained winds of 200 mph, with higher gusts. For comparison, EF-5 tornadoes have winds of at least 200 mph. So, the strongest winds in Patricia were on par with those found in an EF-5 tornado. That is absolutely mind boggling. When it made landfall, winds were substantially lower at "only" 165 mph, but it still ended up being the most intense landfalling Pacific hurricane on record.

Visible satellite loop of Hurricane Patricia approaching the Western Mexican Coast. Credit: University of Miami's Rosenstiel School of Marine and Atmospheric Science

When Patricia was at peak strength, it had a very small eye that was approximately 8 miles in diameter. Small eyes are indicative of intense hurricanes; Hurricane Wilma's eye was only 2.3 miles in diameter, and it remains the smallest eye ever found in an Atlantic Hurricane. Patricia weakened as it went ashore due to it undergoing an eyewall replacement cycle, which is where a new eyewall forms and chokes off the old eyewall, weakening the storm (but often enlarging it in the process). The satellite loop of Wilma from NASA below shows this extremely well... note how the tiny eye eventually becomes filled with clouds and a much larger eye forms in its place.

Eyewall replacement cycles are extremely hard to predict, and as a result, while hurricane track forecasts have improved substantially over the past decade, intensity forecasts have not. On Wednesday evening, NWS models showed the storm deepening to 950 hPa. They were about 70 hPa off... not very good.

Surprisingly, Patricia did not do much damage, and only 7 deaths have been reported thus far. It ended up striking Cuixmala, a super luxurious and remote eco-resort (Bill Gates, Mick Jagger, George Lucas, and a host of others have stayed here). Cuixmala suffered heavy damages, but because of the compact nature of the storm, the two major cities in the area, Manzanillo to the south and Puerto Vallarta to the north, escaped the worst of the storm. Had Patricia made landfall on one of these cities, the damage would have been far worse.

Hurricane Patricia has been an astonishing example of how El Niño affects hurricane formation in the Pacific. During El Niño events, the greatest warm-water anomalies occur near the equator in the central-eastern Pacific, but these warm-water anomalies extend northward into the subtropics, and this, combined with weaker-than-average trade winds there, gives rise to active hurricane seasons.

Credit: NOAA Office of Satellite And Product Operations

The picture above explains it all. You can clearly see the blob of warm water in the tropical Pacific straddling the equator (not to be confused with our precious "Blob" of warm water in the Eastern Pacific that is slowly dying). However, these anomalously warm waters extend northward across the equator into much of the Eastern Pacific. These warm waters (as hot as 86 degrees where Patricia was forming), combined with little wind shear and high humidity, created an exceptionally favorable environment for Patricia to grow into a monster cyclone, and it didn't disappoint!

Patricia absolutely crushed the Pacific hurricane record for minimum low pressure, which was previously held by Hurricane Linda in 1997 with a central pressure of 902 hPa. As I've stated before, 1997 was the biggest El Niño in recorded history, and the jury is out to whether this current El Niño will surpass that one in strength. But the fact that these two incredibly powerful hurricanes occurred on El Niño years is no coincidence. Strong El Niños have massive impacts on weather around the world, and Hurricane Patricia was a textbook example of that.


Saturday, October 17, 2015

What Was the 1997-1998 El Niño Like?

Saturday, October 17, 2015
4:01 pm

Beach erosion by Pacifica, California due to storms during the 1997-1998 El Niño event. Credit: USGS

With all of this talk about the "Godzilla" El Niño of 2015, it's important to remember that an event of this magnitude is not unprecedented. Back during the 1997-1998 winter, we saw the largest El Niño on record, and while the jury is out on whether this El Niño will surpass that one in strength, the effects from this El Niño on weather worldwide are expected to resemble those from the 1997-1998 El Niño. El Niño is not the only factor that decides the fate of our winter, but it is definitely the largest one. Heck, this El Niño was responsible for the destruction of our beloved Blob of warm water off our coast that helped give us 19 straight months of above-normal temperatures.

Therefore, it makes sense to take a look back at the 1997-1998 El Niño and see how the two events have compared thus far. We have weather models to predict our precipitation and temperature anomalies, but climate models do not predict specific events. By looking at the specific events that occurred with the 1997-1998 El Niño, we can get an even better idea of what to expect this coming winter.

Credit: Shrimp News

As this graphic shows, El Niño is truly a global phenomenon. One of the first effects of the 1997-1998 El Niño was a series of devastating wildfires in Indonesia in the summer of 1997. Many Indonesian farmers use slash-and-burn agriculture to create fields, but because Indonesia is so wet, catastrophic forest fires typically do not occur, as the moist soil, summertime downpours, and green vegetation help slow or stop the spread of these fires. However, during El Niño years, convection that typically takes place over Indonesia shifts to the east over the central tropical Pacific, leaving Indonesia much drier and much more prone to these fires. The 1997 Indonesia fires were some of the largest, if not the largest, wildfires in recorded history.

A fire in East Kalimantan province in Borneo, an island of Indonesia. Credit: Global Fire Monitoring Center.

Not surprisingly, 2015 has been a bad year for fires in Indonesia as well. While it has been much better than 1997, nearly 100,000 fires have been detected as of October 15 thus far, more than any other year since at least 2003 (likely 1997, but we did not have satellite fire detection then).

Credit: Global Fire Data

We are on pace to have the worst fire season here since 1997, but as you can see, 1997 was much, much worse. The fires have released over one gigaton of Carbon Dioxide into the atmosphere so far this year, and the season is far from over. That's two BILLION pounds. Think about that. Still, over 8 billion pounds of carbon dioxide were released in 1997, which is more carbon dioxide than the entire European Union emits in a year. Basically, the fires are bad this year, but they are nowhere near as bad as 1997. Thank goodness.

Credit: Global Fire Data

Strong El Niños are also commonly associated with active Pacific hurricane/typhoon seasons due to above-average water temperatures in the tropical Pacific and reduced wind shear. The 1997 Pacific typhoon season (Western Pacific basin) was the most active on record with a record 10 category 5 supertyphoons, and the 2015 Pacific hurricane season (Northeast/Central Pacific basins) has been extremely active as well, with record activity in the Central Pacific. 23 tropical storms have formed thus far, and I have a feeling we will surpass the record of 27 storms set in 1992, also an El Niño year. During late August, there were three major hurricanes occurring simultaneously in the Pacific east of the International Date Line, something that had never occurred in history. It was very impressive, and reminded me of a similar trifecta of storms that was depicted in the extremely realistic climate thriller "The Day After Tomorrow." Meanwhile,  El Niños actually tend to decrease the amount/strength of cyclones in the Atlantic due to increased wind shear, and this year has been no exception.

From left to right, major hurricanes Kilo, Ignacio, and Jimena. Satellite picture taken August 30, 2015. Credit: NASA Earth Observatory
A storm simulation from The Day After Tomorrow. These storms would kill trillions of people and lead to the next ice age. Credit:Climate Change Dispatch

I could go on and on talking about the worldwide effects of the 1997-1998 El Niño. It temporarily warmed the Earth by 1.5 degrees and was responsible for the death of 16% of the world's coral reefs. Although individual places have weather extremes every year, no year in the 20th century was as abnormal worldwide as the 1997-1998 El Niño.

Over the United States, the 1997-1998 El Niño featured wet conditions in the southern states and warm conditions in the northern states, something that is consistent with an active southern branch of the jet stream and a northern branch acting to keep arctic air locked up in central Canada. This is a very typical El Niño pattern, and as a rule of thumb, the stronger the El Niño is, the more probable it is that this pattern will occur. January and February 1998 were the warmest and wettest months ever recorded for the United States, with December 1997 being slightly colder and drier than these two months (but still warmer and wetter than average).

In December 1997, warm and dry conditions dominated the northern half of the country, particularly the northern plains states and the Midwest, as the northern branch of the jet stream prevented arctic air from intruding southward into the U.S. Meanwhile, the southern branch of the jet stream was responsible for cooler-than-average weather in the southeast, with record rainfall in parts of Florida and near-record rains throughout much of the southeast. The Southwest was wet as well, but the effects were not record-breaking (California would go on to have record rains in February). Interestingly enough, the central-southern portions Great Plains and Midwest received above-normal snowfall, as they were cold enough to pick up snow but still had the benefit of the active southern storm track to give them above-normal precipitation.

January 1998 was similar to December 1997 throughout most of the country. Precipitation records were broken throughout the Gulf States, with New Orleans racking up a record 19.28 inches that month. Temperatures in the northern plains, Great Basin, Ohio Valley, and Mid-Atlantic were as high as 10 degrees F above normal for the month in some regions. The Pacific Northwest actually saw above-normal precipitation that month, which is somewhat unusual for an El Niño winter but definitely not unheard of. The Pacific Northwest generally receives near or slightly below normal precipitation in El Niño years. Sea-Tac received 7.15 inches of rain compared to its average of 5.63, and Snoqualmie Pass picked up 149 inches of snow, way above its average of 103.8 for the month.

A powerful, early February 1998 storm that caused flooding throughout California. Credit: NOAA

February was very similar to January and December for much of the nation, with warm conditions to the north and cool temperatures with record rainfall to the south. For example, the average temperature of 29.1 degrees F at Sault Ste. Marie, MI was 15.1 degrees above normal, setting a new record for the warmest February ever. Lake Erie remained unfrozen for only the third winter in history... the last two being 1952-1953 and 1982-1983. Both of these years were El Niño years, and the 1982-1983 El Niño was the second-strongest ever recorded, just being a smidge weaker than the 1997-1998 El Niño. Although the southeast was still wet, California was now making headlines and breaking records as storm after storm pummeled it, causing flooding, mudslides, and substantial beach erosion. Santa Barbara received an incredible 21.74 inches of rain for February alone, setting a new record for the wettest month in recorded history. For comparison, they've only accumulated  20.19 inches since 2013. California would benefit from a lot of rain this year, but the biblical rains they saw in February 1998 caused death and destruction. In other words, let's hope they get really wet, but not really really wet.

A line of tornadic supercells rolling through Florida at 1:55 am. Credit: NOAA

Three weeks later and over 3,000 miles away, the deadliest tornado outbreak in Florida State history occurred. While tornadoes can occur any time of the year (especially in Florida), it is unusual to have them in February. Also, the vast majority of tornadoes that occur in Florida are relatively weak, but this outbreak had several tornadoes that were classified as upper-level F3 twisters. These struck between 11:30 pm February 22 and 2:30 am February 23, and because of their unfortunate timing when many people were sleeping and did not have time to escape, this tornado outbreak is colloquially known as the "Night of the Tornadoes" and remains the deadliest outbreak in Florida history.

In conclusion, the 1997-1998 winter (December-February) was super wet with average temperatures to the south and super warm and relatively dry in the north. The map below summarizes the winter quite nicely.

Credit: NOAA

In this map, the numbers represent how the precipitation total and average temperature of the state compare to 103 years of historical record, with 1 being the coldest/driest and 103 being the warmest/wettest. The northern Plains states and the Midwest were exceptionally warm, with most states either having their warmest or second-warmest winter ever, and many of them were relatively dry as well. The southern states saw more-or-less average temperatures, but they were slightly below average during rainy periods. They were exceptionally wet, particularly in the southeast during December and January and the southwest during February. Here in the Pacific Northwest, we escaped relatively unscathed, and our snowpack was only slightly below normal.

At first glance, it would seem like we should expect very similar conditions for this winter. Both of these El Niños are similar in strength, and they are the main driver of the climate system. However, there are important differences between this El Niño and the 1997-1998 El Niño. For example, the 1997-1998 El Niño was strongest in the Eastern Pacific, while this El Niño was been strongest in the Central Pacific thus far. Additionally, even if the El Niños were identical, the world is different now than it was in 1997-1998. Other oscillations like the Pacific Decadal Oscillations are in different states now than they were during the last El Niño. The world is warmer now than it was back then, with less arctic sea ice. You get the idea.

Still, we've seen fires in Indonesia, a historically active Pacific hurricane season, and catastrophic flooding in the southeast. And this El Niño continues to become stronger. Nobody knows for sure, but preliminary winter forecasts are calling for warm and dry to the north and wet to the south, first the southeast and then California as winter progresses. WeatherOn is releasing an extended winter outlook on November 1st that will cover the entire country, so stay tuned. Spoiler alert: Seattle is going to be colder than last winter.

Thanks for reading!

Thursday, October 15, 2015

Why Are Our Evergreens Turning Brown?

Thursday, October 15, 2015
3:52 pm

Every autumn, our beloved deciduous trees shed their leaves, creating an annual economic boom for children everywhere as parents and neighbors pay them the proverbial quarter to rake excess leaves off their lawns. Of course, once these upstart entrepreneurs have reaped the monetary rewards of their labor, they get to romp around in the leaves until they are spread all over the yard again. I would give anything to go back to those days. But since I can't, I'll bore you with a blog on tree biology.


These types of trees are called "deciduous" trees, while those that keep their leaves all year long are called "evergreens." However, even evergreens do a little shedding, and this autumn, they appear to be more ambitious than usual.

I happen to have a pretty sizable Western Red Cedar in my front lawn, and this bad boy is as brown as I have ever seen it. I took this picture on Monday the 12th, and it really makes you question whether this cedar tree is deserving of the title "evergreen."

Flagging on a cedar tree in my front yard. Taken October 12, 2015

So what's with the brown "flagging" on this Cedar tree? Why are the evergreens doing this so much this year, and will there be any green left for our winter? The answer is yes, and there are two main reasons why.

First, we had a hot and dry summer. Cedars and many other conifers (trees with needles, like Firs, Spruces, Pines etc.) have relatively shallow root systems. This makes them vulnerable to drier and hotter-than-normal summers, as the upper soil responds more quickly to precipitation and heat than the soil deeper down.

A Douglas Fir pulled straight out of the ground at Avery Park, Oregon due to the Hanukkah Eve Storm of 2006. Note how shallow the roots are. Credit: Wolf Read's Storm King Website

This summer, soil moisture was significantly less than average both in the lowlands and mountains, which did not have the benefit of a large winter snowpack to keep the ground moist well through spring. The majority of water loss from a tree occurs through its foliage, so it makes sense that the tree would kill some of these needles to conserve water. If water was low but the tree kept all of its leaves, it would lose even more water, potentially killing the tree. Cedars always flag in the autumn, so the fact that this summer was much hotter and slightly drier (our heavy rains in August made up for much of our deficit) than normal explains why the flagging this year is more prominent than years past.

Second, conifers shed old limbs so they can devote more resources and water to growing new ones, meaning that even in the wettest of years, cedar trees still undergo flagging. On average, Seattle only gets 37 inches of precipitation a year, which is approximately the same amount that Dallas gets. If our trees tried to equally distribute water, they would grow very slowly. Trees in the Hoh Rainforest tend to experience less flagging because of the wetter climate, but needles that are several years old still die every year as the tree focuses on new growth, allowing them to grow to unbelievably massive sizes.

"Big Cedar Tree" with a girth of over 66 feet in Olympic National Park. Credit: Tom and Dianne's North American Adventure

Although the term "flagging" is mostly reserved for cedars, most conifers shed old needles in the autumn, particularly after a hot, dry summer.

There are a number of conifers that actually are deciduous. Most of these are Larches, but some Cypress trees and even the Dawn Redwood have this quality. Meanwhile, there are some non-coniferous trees and shrubs that are evergreens. For example, our state flower, the Pacific Rhododendron, is an evergreen shrub.

A Pacific Rhododendron in Olympic National Park. Credit: Walter Siegmund

Hope you enjoyed a different type of weather blog for today! It's fun to mix things up. Keep an eye out for WeatherOn's winter forecast, which will be released on November 1st. Right now, it looks like we are going to be warmer and slightly drier than normal, but nowhere near as warm as last year. I'd still hold off on a seasons pass until the 2016-2017 winter though.


Thursday, October 8, 2015

The Tragedy of Climate Misinformation

Wednesday, September 23, 2015
3:52 pm            

Albuquerque Tea Party, April 2009

Global warming deniers come in all shapes and sizes. Some are quite bold in their statements, denying any reasonable scientific claim, and instead claiming that global warming is a 'socialist scam.' Others are more subtle, claiming that evidence for the Earth warming is "inconclusive." And then there are others that claim that yes, the Earth is indeed warming, but there is no evidence that humans are causing it. Some will go so far as to say that the very thought of humans being able to influence the climate is a manifestation of the arrogance of mankind. Pretty ironic, huh?


But we also know about the global warming alarmists. The "Chicken Littles" of society. Just like the deniers, no matter what you say to them, they'll deny the science and instead claim that global warming is going to destroy us all. And just like the deniers, there are the true "air raid siren" alarmists who go door-to-door prophesying the end of the world as we know it, and those who simply pass on alarmist misinformation from biased, unreliable sources.

I firmly believe that the vast majority of both deniers and alarmists are not to blame for their ignorance when it comes to climate change. Instead, I think the blame falls on a few self-appointed experts on climate change, our politicians, and most of all, the media.

I did a quick Google search for "Climate Change," and here are some recent news articles I found.

The Guardian
The Guardian

Articles like these frustrate me immensely. The first article ties a slight (10% increase over the past few decades) increase in precipitation to massive rainfall totals this year that destroyed pumpkin crops, thus blaming climate change on pumpkin pie shortages. Yes, climate change will increase precipitation intensity in many places around the world, but blaming a massive rainfall event solely on climate change? There are so many other variables to consider, most notably the goliath El Niño event currently underway in the tropical Pacific. As far-fetched as this article is, it is significantly more reasonable than the three below it.


I also checked out the positions on climate change of the top two GOP candidates from the most recent Pew Research Center poll this October. Front runner Donald Trump (25%) says climate change is a hoax created by the Chinese to distract the United States and allow the Chinese to overtake our economy, while Ben Carson (16%) believes that the climate changes any time that the temperatures go up or down. This theme is common throughout the party, both for the candidates and the others in politics. I believe that most of them actually do believe that anthropogenic climate change is real, but they deny it to gain support from certain industries and their voter base.

Finally, let's not forget about the wacko scientists who make false claims about global warming.

Dick Lindzen. Credit: The Cato Institute

The most notorious of these climate swindlers is Dr. Dick Lindzen of MIT. The thing about Dr. Lindzen is that he is a very smart dude. If I had a debate on climate change with him, I would lose, even though I am right and he is wrong. He has published over 200 scientific papers, and was the Alfred P. Sloan Professor of Meteorology for 30 years. He even did work for the Intergovernmental Panel on Climate Change. He focused his career on atmospheric dynamics and significantly advanced knowledge of that area in our field. He's a genius.

But he's also a contrarian. Not only does he deny anthropogenic global warming, he denies that smoking plays a significant role in causing lung cancer. It's OK to have opposing viewpoints when evidence supports them, but Lindzen relishes the contrarian label. Numerous scientists, including professors I know, have categorized him as "intellectually dishonest," "deeply unprofessional," a "formidable opponent," etc. Naturally, he's gone on places like Fox News to discuss his views, and viewers just assume he is right because of his credentials. If I didn't know anything about climate science, I know I would.

Another disturbing thing is that, according to a 2015 George Mason University study, only 74% of broadcast meteorologists believed that human activity was at least half to blame for global warming. When this study was done in 2011, only 65% of broadcast meteorologists held this view.

With all of this misinformation floating around, it's no wonder that the public is so confused about climate change.

I believe that things will get better as time goes on and global warming becomes more apparent. There will be fewer and fewer deniers, both in the atmospheric science community and elsewhere, and as climate change becomes more and more of a mainstream topic, the public will become better educated on what it actually is.

In the meantime, there are some fantastic resources for getting accurate information on climate change. I highly suggest reading the EPA's page on climate change, and NOAA's Earth Systems Research Laboratory is a great resource as well.

One of the biggest misconceptions floating around is that you can attribute an individual event to climate change. For example, right after Hurricane Sandy, there were tons of articles linking that singular event to climate change, even though there was some evidence that hurricanes in that part of the Atlantic would be less likely under global warming. Asking whether an individual event can be attributed to climate change misses the entire point of climate change... it focuses on long term climate, not day-to-day weather. Every weather event is affected by anthropogenic global warming because the climate in which it occurs is warmer and moister than it otherwise would be if humans never emitted greenhouse gases. In order to truly see evidence of climate change, you have to look for signs of the climate, well, changing. Hurricane Sandy is not an example of the climate changing, but the Earth warming over 1.5 degrees Fahrenheit since 1880 is.

Credit: NOAA's National Climatic Data Center

And when you consider that 93% of the additional heat due to man-made climate change is going into the ocean compared to just 2% for the atmosphere, you can see that global warming is very real, and very serious. But it as serious as this?

Credit: History Today

I don't know about the UK minister, but I'll take global warming over nuclear war.


Tuesday, October 6, 2015

Will Hurricane Oho Impact the Pacific Northwest?

Tuesday, October 6, 2015
3:29 pm

A tower atop Campbell Hall, Western Oregon University collapsing under the 100+ mph winds of the Columbus Day Storm. Credit: Wes Luchau, Statesman Journal

The Pacific Northwest has never gotten hit by a hurricane and never will. Our waters are simply too cold to sustain a tropical system. For a hurricane to form and keep its strength, you generally need to have 80+ degree water extending from the surface to at least 150 feet. The summer water temperatures off our coast are in the mid-50s due to the upwelling of deep, cold, nutrient-rich, acidic water (good for salmon, bad for Willapa Bay oyster larvae). But we can get the extratropical remnants of these storms, and due to the deep, tropical moisture source they provide, they can turn into quite vicious midlatitude cyclones.

The strongest of these was the Columbus Day Storm, which devastated the entire Pacific Northwest on October 12, 1962. No extratropical storm we've seen here or anywhere else in the United States can compare to the winds witnessed on that day. Not Superstorm Sandy, not the "Storm of the Century" of 1993, and certainly not the "Perfect Storm" of 1991. The map of peak gusts from the storm below speaks for itself.

Credit: Wikipedia User Spiritchaser

The Columbus Day Storm started out as Typhoon Freda, which reached category-3 status and had a minimum pressure of 948 millibars. As it traveled north, it became more entrained in the prevailing midlatitude westerly flow, and as a result, it weakened into an extratropical cyclone just before the International Date Line. As you can see, it sped up tremendously while retaining its structure. Just off the Northern California coast, it explosively redeveloped after interacting with a very strong jet stream, and the Columbus Day Storm was born (or resurrected, depending on how you see it).

The track of Typhoon Freda. The points are at 6-hour intervals, and circles represent a tropical system, while triangles delineate an extratropical one. Credit: Supportstorm

Yeah, it's fair to say I'm pretty obsessed with the Columbus Day Storm. It just kills me that I wasn't there to experience it. Nonetheless, I can't help but get excited every time there is talk of an ex-hurricane or typhoon hitting us. 

As it turns out, there is a specific tropical cyclone a little bit east of Hawaii. And the name of that tropical cyclone is Hurricane Oho.

Credit: Central Pacific Hurricane Center

Fortunately, Hurricane Oho does not appear to be a serious threat to the Pacific Northwest. This evening's model runs are forecasting a landfall near Haida Gwaii as a strong and compact extratropical storm. However, this morning's model runs showed it coming ashore Vancouver Island as a weak blob of rain. The general trend with the models has been to push Oho further westward and make it stronger, so while I doubt we will feel any effects here besides a few showers from a trailing cold front, it will be interesting to watch how this system evolves. The latest UW WRF-GFS model shows it making landfall as a 963 mb cyclone Friday morning, which is not that much weaker than the Columbus Day Storm. 

Valid 11:00 am PDT, Fri 09 Oct 2015: UW WRF-GFS

I'm not gonna lie... I'm a little bummed that Oho has its sights set on Alaska, and I don't think that will change. Still, it will be fascinating to study Oho's evolution from a tropical to an extratropical system as it races north, especially near the 53rd anniversary of the Columbus Day Storm. Stay tuned... this will be a storm to watch!

Thanks for reading,

Monday, October 5, 2015

Historic Flooding in South Carolina

Monday, October 5, 2015
2:49 pm

Flood waters in Charleston at intersection King Street and Huger. Credit: US Army National Guard

The Pacific Northwest is no stranger to flooding. I believe that Washington has had the most federal disaster declarations of any state, which may be surprise you due to our seemingly-mundane weather. But we get these massive floods from time to time, and we also have a tendency to get strong winds, especially on the coast. We have extremely heavy snows and avalanches in the mountains as well. Our natural disasters aren't just limited to the weather... we've got earthquakes, volcanoes, and landslides too. Let's not forget about those wildfires either. When you think about it, we live in a pretty disaster-prone place, even though it might not seem like it when it rains an entire day and we've only got a tenth of an inch of liquid sunshine to show for it.

But there are times when we are reminded that no matter how hard we try, we just can't outdo some of the severe weather found in other parts of the country. And this is one of those times.

The stalled rain band over South Carolina on 16:10z October 3, 2015. Notice Hurricane Joaquin to the southeast. Credit: NASA Worldview Terra MODIS Satellite

South Carolina is just recovering from an extraordinary rainfall event, and North Carolina got hit pretty hard as well. The rainfall was primarily caused by two things: strong easterly flow due to a low pressure center over the southeast and a high pressure system way up north by Hudson Bay and convergence due to air circulating around the southeast part of the low. Converging air rises and forms clouds and precipitation, and in this case, there was a lot of convergence, and therefore a lot of rain. Additionally, once this stream of moisture went ashore and interacted with terrain, the air was forced to rise more, resulting in even heavier rainfall. This rain was NOT directly associated with Hurricane Joaquin, which was just to the southwest. However, Joaquin did provide a tropical moisture source which further contributed to the heavy rainfall. In the end, the strength of the convergence, the uplift from terrain, the stationary nature of the rainband, and the influence of nearby Hurricane Joaquin all combined to create a massive flooding event for Southern Carolina.

Rainfall accumulations across the Carolinas and surrounding states from October 1–4, ending at 6:24 p.m. EDT (22:24 UTC). Areas in white indicate accumulations in excess of 20 in (510 mm). Credit: Raleigh, NC NWS Twitter Page

The picture above shows 4-day rainfall totals from October 1-4 ending at 6:24 pm EDT on the 4th. As such, it does not represent final rainfall totals, but it represents most of what they got. The rainfall is off the charts. The chart only goes up to 16 inches, but those areas of white that you see in South Carolina represent areas where over 20 inches were estimated to have fallen! The Pacific Northwest has had very impressive rainfall totals before, but I can't remember anything like this, especially for lowland areas. For South Carolina, many locations got over 20 inches, and while this was measured over four days, the majority of the rainfall occurred over the weekend. Here are some South Carolina rainfall statistics I found on (I'm sure they got them from the National Weather Service). Amounts are in inches, and these are through October 4th.

Mount Pleasant: 26.88
Kingstree: 21.80
Dalzell: 21.66
Georgetown: 20.95
Sumter: 19.43
Summerville: 17.75
Charleston Airport: 17.29
Moncks Corner: 17.02
Charleston (Downtown): 16.29
North Myrtle Beach: 13.84
Columbia (Downtown): 11.93
Greer: 6.30

By the way, the previous state record for most rain in 24 hours was 14.80 inches, set in 1999 with Hurricane Floyd. Numerous places smashed this record.

Mt. Rainier National Park: Left pic, November 5, 2006. Right pic: same location two days later. Credit: National Park Service

Washington has had many major flood events, and I remember one back in November 2006. An incredible amount of rain fell throughout Western Washington and the Cascades from November 5 to November 7. I went to Snoqualmie Falls on November 7 - a Tuesday - and it was as muddy and high as I had ever seen it. It was something of a spiritual experience for me. Still, Seattle got 3.29 inches on the 6th, good for our 4th rainiest day ever (the rainiest day was October 20, 2003, when Sea-Tac picked up 5.02 inches of rain!). Meanwhile, Charleston got 11.50 inches of rainfall on Saturday, breaking their old record of 10.52 inches set back on September 21, 1998. We can get very wet here and have catastrophic flooding both in the mountains and very rarely in Seattle (the December 14, 2006 flood comes to mind, where a woman in Madison Valley died), but being in such a moderate climate, we tend not to see the flash flooding that South Carolina got this past weekend.

You'll see many media reports saying that this is a "once in a thousand years" flood event. I decided to take a look at this, and it turns out that while this event is unprecedented in many areas, the "once in a thousand years" might be a bit overstated. Technically speaking, "once in a thousand years" means that an event of this magnitude has a .1% chance of occurring any given year, but headlines like "South Carolina Reeling From ".1% Chance Of This Bad Of A Flood Occurring Any Given Year" Flood" just don't, well, make that much money.

There's also talk of climate change, but keep in mind that heavy rainfall events have always happened and always will. There is evidence that heavy rain events will increase in severity (for example, more "Pineapple Express" flooding events are expected here in the Pacific Northwest in a warming climate), but it is far from conclusive. Besides, the global warming signal is fairly weak throughout the globe right now with the exception of the far northern latitudes. Long story short... let's talk about the "new normal" in 2100, when our climate will be significantly different from what it is today. The climate is not much different today than it was 20 years ago.

Historic rainfall in SC -- only happens once every 100-200 years. Credit:

The National Weather Service compiled a neat little graphic showing the return period of events like these, and it looks like it's more of a 100 to 200-year event for most places. There are some places where it looks to be off the charts and that the "1000-year event" label is justified, but these places look few and far between. The media can be very misleading... don't let it fool you!

Enjoy the nice weather here! We'll have a couple weak systems coming through this week, but nothing major. However, I don't think it's misleading to say that storm season is right around the corner!

Thanks for reading,

Friday, October 2, 2015

Another Heat Record Bites The Dust/Thoughts on The Blob

Thursday, October 1, 2015
4:08 p.m.

"It ain't the heat, it's the humility" - the late, great Yogi Berra

At Sea-Tac, the last time we had a month that was cooler than average for that month was February 2014. Since then, 20 months have passed, with 19 consecutive months being warmer than normal. That's right... this September was the first colder than normal month since February 2014.

We've broken some impressive records in that time. Our records to Sea-Tac go back to January 1948, but within the span of these months, we've broken two all-time records for hottest months (March 2015 and June 2015). In addition, December 2014 and June and July 2015 broke records for all-time highest maximum temperature, and October 2014 and February, March, June, and July 2015 broke record for all-time highest minimum temperature. In other words, these 19 months weren't just warm, they were scorching!

Why so warm?

Two answers: a massive and persistent ridge of high pressure, and a larger-than-life blob of boiling-hot (OK, maybe not that hot, 2-3 degrees warmer than normal) water in the Northeast Pacific. With this ridge, instead of getting cool, northwesterly flow from the Gulf of Alaska and places to the Northwest, we got warmer flow originating from our south, and our surface winds were often offshore, further warming us due to downslope adiabatic warming effects off the Cascades (that's fancy terminology for the phenomenon of air warming as it sinks). With the warm water, onshore flow off the Pacific into our region was often at least 2 degrees higher than it would have been due to the long time it spent over the Blob of warm water. 

The picture above shows our sea-level-pressure compared to normal values, and you can clearly see that we had higher than normal pressure this summer. As you can see, we clearly had higher than normal pressure over the Northeast Pacific this year.
This ridge of high pressure was associated with relatively little mixing of the ocean, so the surface got nice and warm instead of having this warmth being mixed down deep by storms and waves. Also, these ridges are associated with sunny skies, so the sun heated the ocean.

I was unable to find out how to get a similar chart to this for sea surface temperature (SST), but as you can see from the February-March 2015 SST anomaly chart below, the "Blob" is located in the same area that the higher-than-normal pressure is located. This is not a coincidence! The Blob is a direct result of this higher-than-normal pressure.

As you can see below, the Blob wasn't just present in 2015. It was there in 2014 too; in fact, that is when it was first named. It was a bit further west, and a bit more "blob-like" then (at least in my opinion).

Credit: NOAA Earth Systems Research Laboratory: Physical Science Division

So, why did this persistent ridge of high pressure (and the resulting Blob) occur? There's been a lot of study concerning it, particularly at the University of Washington, where Professor Nick Bond (great guy, had him for my senior capstone forecasting course spring quarter) first came up with the "Blob" name. It turns out that the high pressure looks to have originated from atmospheric waves originating from the western Pacific. On a larger time scale, the Pacific Decadal Oscillation, an oscillation in Pacific Ocean temperatures on 20-30 year time scales that has atmospheric implications, may be a factor. Finally, some studies like those by Diffenbaugh et al. (2015) have hypothesized that we will see more of these "Ridiculously Resilient Ridges" and therefore Blobs in a warming climate. This is likely due to a weakening meridional temperature gradient, as the poles (particularly the North Pole) are warming faster than the tropics and midlatitudes. This creates a weaker "polar vortex" (yes, the infamous vortex you hear about on CNN) and allows strong ridges of high pressure to occur in some regions while other regions have large troughs and arctic outbreaks. When the vortex is all wavy like this, it is weak and in a "highly amplified" pattern. I know amplified = more powerful most of the time, but in this context, it refers to a lot of ridging and troughing. A strong, non-amplified polar vortex is said to be "zonal." And yes, our record breaking heat and the eastern U.S.'s record breaking cold as of late are directly related... we've had the ridge, and they've had the trough.

Thanks to the strong, potentially record-breaking El Nino, the Blob is pretty much toast, and our winter won't be as warm as last winter. I don't think we'll have 19 consecutive months of above average temperatures soon, but as we go further into the 21st century and really start to feel the effects of global warming, we'll shatter more and more heat records. Someday, air conditioning may be a standard feature for Seattle homes. That’ll probably have to do more with our rapidly growing economy than rapidly warming climate though.

On that happy note, enjoy some cooler weather. Sunday should be beautiful, but we should have typical early October weather for this time of the year this coming week. Come late October, things will start to feel a lot different. The transition to storm season is a lot more abrupt than the transition out of it!

Thanks for reading,