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Hurricane Season isn't over - the West Coast is getting hammered [1]

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Date: 2023-01-07

This is one of the storms (on January 4, 2023) that have been hitting the west coast,

From gCaptain:

The Other Hurricane Season Each year there are, on average, about 6 hurricanes in the North Atlantic, 8 in the Eastern North Pacific and 17 Typhoons in the western North Pacific. Few people (outside of Mariners) realize that there is another season of hurricane winds that occurs over both the North Atlantic and the North Pacific Ocean and runs from September to May. These storms do not track through the tropics, but instead are associated with the extratropical cyclones of the mid-latitudes.

emphasis added

The storms don’t have the same ‘eye’ formation as the tropical versions, but that doesn’t mean they can’t be classed as severe weather. Bomb cyclones are no fun. From the same article about the storm on January 4, 2023:

An intense storm low over the eastern North Pacific is currently moving towards the northeast at about 20 kts and is producing winds of 50-70 knots with significant wave heights up to 12.5-13.5 meters (41-45 feet) within 120-360 nm south and west of the center. NOAA forecasters have issued gale to storm warnings along the entire US West Coast where hurricane force wind gusts are possible along with heavy rain and snow over land.

The article includes graphics and videos that give an idea of how massive these storms are.

If you’ve been following the news, California has been hit with storms that have dumped inches of rain and up in the Sierra Nevadas, snow by the foot. This is welcome news after years of drought — or would be if it wasn't happening all at once in huge volumes.

Weather systems are generating a series of storms out in the Pacific that are headed for the West Coast. The middle of the country has been experiencing serious weather resulting from these incoming weather systems spilling over the Rockies after hitting the coast.

What is happening is what are called atmospheric rivers, masses of water vapor described as equivalent to the amount of water pouring out of the mouth of multiple Mississippi Rivers.

The dynamics of these storms themselves explain why the state [California] is also prone to such swings. Meteorologists have known for decades that those tempests that descend upon California over the winter—and from which the state receives the great bulk of its annual precipitation—carry moisture from the South Pacific. In the late 1990s, scientists discovered that these “pineapple expresses,” as TV weather presenters call them, are a subset of a global weather phenomenon: long, wind-driven plumes of vapor about a mile above the sea that carry moisture from warm areas near the equator on a northeasterly path to colder, drier regions toward the poles. They carry so much moisture—often more than twenty-five times the flow of the Mississippi River, over thousands of miles—that they’ve been dubbed “atmospheric rivers.”

The Guardian has an explainer about bomb cyclones, atmospheric rivers, La Nina, and how climate change is affecting them all.

Tracking the Rivers in the Sky

The Hurricane Hunters of the 53rd Weather Reconnaissance Squadron out of Keesler Air Force Base shift from missions tracking the storms coming across the Atlantic after that season dies down to flying missions off the West Coast to track the incoming atmospheric rivers. This video, although it deals with a flight into a tropical hurricane, gives a good look at the WC-130 Hercules aircraft they fly and the equipment they have on board.

For the crews, missions require operating from airfields near the storms. For the tropical hurricane season, crews may fly out of islands in the Caribbean, or up the east coast depending on the storm track. The idea is to be close enough to make flights to the storm not too long, but far enough away to avoid having their airfields shut down by them. For the winter missions, they’ll operate out of places like Reno or northern California.

Satellites can get data and images from above, but some things can only be found out by flying out over the water into the weather.

What’s it like in California?

Rayne at Empty Wheel posted this January 5, 2023.

There are numerous warnings and advisories about the extreme weather event underway in California. The central portion of the state is and will be hardest hit over the next 12-24 hours because of a “bomb cyclone” but the entire state will feel the effects in varying degrees. In no small part it will be due to the accumulation of rain before this cyclone; the ground in many area is already waterlogged and unable to soak up more water. As you can see from this California Water Watch map based on Tuesday’s data, portions of central CA had already passed 200% of the year-to-date precipitation before the cyclone hit. ...Power outages are ongoing, some beginning late morning Wednesday. The entire Mission district in the Bay area went dark in early evening local time; by 10:00 p.m. 100,000 residents had lost power in the region. (Gee, I wonder how Silicon Valley and San Jose are handling this weather event.) Portions of Santa Cruz upgraded from evacuation warning to evacuation ordered. I listened to a podcast Wednesday evening on KQED featuring Daniel Swain, climate scientist, Institute of the Environment and Sustainability at UCLA; Brian Garcia, warning coordination meteorologist, National Weather Service SF Bay Area/Monterey; and Gerry Diaz, newsroom meteorologist, SF Chronicle. I was struck by how blasé and banal some of the inquiries to the station were, like how to deal with problematic trees, or whether a person living less than 14 feet above sea level on a canal might be at risk of flooding. It was already far too late to be asking these kinds of questions when much of the area was already without power, the coastline was surely being battered by gale and hurricane-force winds, and people should have evacuated 12 hours earlier. So much denial.

Rayne notes in passing the irony of Kevin McCarthy being put through the wringer by people who will do nothing to address any of this, while back in California his constituents are floating away...

Rayne has this for resources, for those still able to go online:

If you’re in California, please, please, PLEASE heed the National Weather Service’s warnings about conditions in your area. Mastodon user Jenny from the Bloc (@[email protected]) pulled together a nice list of informational links for use by Californians and curious folks outside the Golden State: https://aware.zonehaven.com/search – map of evacuation orders and statuses (not complete – only works where integrated with local services) https://pgewam.lovelytics.info/pge_weather_app/ – pg&e-run weather map with information on winds, precipitation, and more https://pgealerts.alerts.pge.com/outages/map/ – pg&e-run map of outages. lets you search by address https://poweroutage.us/area/state/california – third party map of outages. does *not* let you search by address https://calalerts.org/ – landing page for county-based emergency alerts. note that each county runs their own system, so if you want to keep track of multiple locations in different counties you will need a unique account for each county https://sfplanninggis.org/floodmap/ – hypothetical flood risk map for city of sf (NOT real time) https://tidesandcurrents.noaa.gov/map/# – noaa-run map of tides, water levels, meteorological observations, and more https://marin.onerain.com/map/?view=www_marincounty – marin-based map of winds, precipitation, river levels, and more https://www.oaklandca.gov/topics/winter-storms city of oakland’s dedicated winter storms webpage with further links to oakland-specific resources https://www.windy.com/ – weather map with information on temperature, precipitation, air quality, and more https://quickmap.dot.ca.gov/ caltrans-run map of road conditions https://sonomacounty.maps.arcgis.com/apps/webappviewer/index.html?id=69a0e54e9e2b48c086d122027b21c961 – sonoma county evacuation map

https://slvpost.com/at-home-when-debris-flow-strikes-there-is-hope/ – article about recognizing and responding to debris flows (land slides, mud slides, etc) https://www.wunderground.com/ – weather site that is extra useful for under-served areas https://alert.valleywater.org/map?p=map – surface water data & map for the south bay https://www.cityofpaloalto.org/Departments/Public-Works/Engineering-Services/Creek-Monitor-Cam creek monitor and camera for palo alto https://www.nytimes.com/interactive/2022/08/12/climate/california-rain-storm.html – not about this storm in specific, but an interactive article predicting exactly this kind of storm, explaining how we got here, and exploring what we can do to respond to storms of this type. For the rest of our community members, do spend some time this week checking your emergency/disaster preparedness plan.

One more thing — do NOT drive through water. It takes a surprisingly small amount of moving water to wash a vehicle away or knock someone down. Turn around — don’t drown.

How Bad Could It Get? Biblically Bad

Pretty much everyone has heard of the 1906 Great San Francisco Earthquake — but it’s only recently that people have become aware of a far greater natural disaster that hit California in 1861-62. The winter rains started that year as usual — then did not stop for weeks. Central California became a lake several hundred miles long; the loss of life and property damage was immense. (The current long term forecast for Sacramento includes what looks like another 2 weeks with rain.)

What makes it of particular interest is that geological evidence suggests this happens every 100-200 years or so, and it might be coming around again. If so, the damage will be in the trillions and the loss of life will be far higher. Mother Jones featured an article by Tom Philpott in 2020 that looked at the history of the event, and the current science attempting to understand it.

Beginning in the 1980s, scientists including B. Lynn Ingram began examining streams and banks in the enormous delta network that together serve as the bathtub drain through which most Central Valley runoff has flowed for millennia, reaching the ocean at the San Francisco Bay. (Now-vanished Tulare Lake gathered runoff in the southern part of the valley.) They took deep-core samples from river bottoms, because big storms that overflow the delta’s banks transfer loads of soil and silt from the Sierra Nevada and deposit a portion of it in the Delta. They also looked at fluctuations in old plant material buried in the sediment layers. Plant species that thrive in freshwater suggest wet periods, as heavy runoff from the mountains crowds out seawater. Salt-tolerant species denote dry spells, as sparse mountain runoff allows seawater to work into the delta. What they found was stunning. The Great Flood of 1862 was no one-off black-swan event. Summarizing the science, Ingram and USGS researcher Michael Dettinger deliver the dire news: A flood comparable to—and sometimes much more intense than—the 1861–1862 catastrophe occurred sometime between 1235–1360, 1395–1410, 1555–1615, 1750–1770, and 1810–1820; “that is, one megaflood every 100 to 200 years.” They also discovered that the 1862 flood didn’t appear in the sediment record in some sites that showed evidence of multiple massive events—suggesting that it was actually smaller than many of the floods that have inundated California over the centuries.

emphasis added

The Philpott article is a long read, but it’s full of unsettling information and graphics. What would another megaflood do?

Starting in 2008, the USGS set out to answer just that question, launching a project called the ARkStorm (for “atmospheric river 1,000 storm”) Scenario. The effort was modeled on a previous USGS push to get a grip on another looming California cataclysm: a massive earthquake along the San Andreas Fault. In 2008, USGS produced the ShakeOut Earthquake Scenario, a “detailed depiction of a hypothetical magnitude 7.8 earthquake.” The study “served as the centerpiece of the largest earthquake drill in US history, involving over five thousand emergency responders and the participation of over 5.5 million citizens,” the USGS later reported. That same year, the agency assembled a team of 117 scientists, engineers, public-policy experts, and insurance experts to model what kind of impact a monster storm event would have on modern California.

What they estimated — for a storm not as big as the 1861-62 event:

What they found stunned them—and should stun anyone who relies on California to produce food (not to mention anyone who lives there). The headline number: $725 billion in damage, nearly four times what the USGS’s seismology team arrived at for its massive-quake scenario ($200 billion). For comparison, the two most costly natural disasters in modern US history—Hurricane Katrina in 2005 and Harvey in 2017—racked up $166 billion and $130 billion, respectively. The ARkStorm would “flood thousands of square miles of urban and agricultural land, result in thousands of landslides, [and] disrupt lifelines throughout the state for days or weeks,” the study reckoned. Altogether, 25 percent of the state’s buildings would be damaged. In their model, 25 days of relentless rains overwhelm the Central Valley’s flood-control infrastructure. Then large swaths of the northern part of the Central Valley go under as much as twenty feet of water. The southern part, the San Joaquin Valley, gets off lighter; but a miles-wide band of floodwater collects in the lowest-elevation regions, ballooning out to encompass the expanse that was once the Tulare Lake bottom and stretching to the valley’s southern extreme. Most metropolitan parts of the Bay Area escape severe damage, but swaths of Los Angeles and Orange Counties experience “extensive flooding.”

Is this the start of another megaflood? It depends on how long storms keep rolling in from the Pacific. We can’t say exactly when it will happen — but we can expect, given the historical record, that’s it’s only a matter of time. We can also expect that climate change will likely make it — and many other things — worse.

It wasn’t all that long ago that Pakistan was flooded to record levels in 2022. In 2021 Europe suffered devastating floods; in 2022 the story was drought. The Mississippi has hit low levels that have been affecting shipping. We are heading into the unknown as far as weather events go; if California is about to have another megaflood, it will fit right in.

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[1] Url: https://www.dailykos.com/stories/2023/1/7/2145864/-Hurricane-Season-isn-t-over-the-West-Coast-is-getting-hammered

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