Tag Archives: flooding

California Flood Worst Case Scenario (hypothetical yet real) UPDATED

Regarding the real storm hitting California right now, 30,000 are being urged to evacuate. There is more informaiton about that storm down at the bottom of the post.

Meanwhile, on the hypothetical worst case scenario for flooding in California…

If an ARkStorm were to come to the US West Coast, this is what the flooding in California could look like: Continue reading California Flood Worst Case Scenario (hypothetical yet real) UPDATED

More’easter Jonas Looks Like The Real Deal (UPDATED Storm shifts to the north)

Friday AM Update: Overall the storm has shifted north. Washington DC is still on track to have something close to two feet of snow in the city, more to the west. The predicted snowfall for New York City, the city that eats meteorologists, is increasing, and The City may see a foot or more, with closer to two feet to the northwest. DC will have its most intensive snowfall during the night on Friday, while New York City will have most of its snow falling during the day on Saturday.

With this northward shift, Boston is likely to get more snow too, possibly over a foot. Snow will start there during the afternoon on Saturday and continue through Sunday AM and early PM.

Wave and storm surge erosion with winds gusting to 50 MPH along the coast is still expected, especially along coastal New Jersey, Long Island, southern New England, Cape Cod, and down south across the Delmarva Peninsula. Normal tides are strong this time of month. Expect power outages here and there.

Regardless of the apparently senseless and, frankly, mean spirited comments we see from some of the climate science denialists (i.e., that blizzards have happened before therefore…) it is simply true that most of the big storms that have hit this area since good record have occurred in just the last few years. That’s the observation. These storms are made worse by global warming enhanced sea surface temperatures. That’s part of the mechanism. Changes in jet stream patterns have also probably played a role in both the concentration of moisture and the length of storms, and their tracks. So, yes, this is a global warming enhanced storm that earns an extra merit badge for having a bit of extra energy from El Nino.

See THIS for more about the science behind the predictions and the storm itself.

A quick update (Thursday 10:30PM Central). Not much change in the overall pattern, but the “most likely” amount of snow for DC and environs has increased. You’all are likely to get way over a foot, possibly 20 inches or so, maybe more. The minimum is 9 inches. That’s not too likely. Overall, predicted snowfall amounts are increased. New York is expected to receive a half a foot or more, but as I note below this is hard to predict for that area. The estimate of snow for Boston has gone down, most likely an inch or so. But, that estimate has a fat tail, and it could be much more in the Boston area or East/Central Mass (up to 10 inches). Coastal flooding in New York, New Jersey, Delaware, Maryland and parts of Virginia are still expected.

I had previously mentioned Jonas, the storm about to bear down on the US East Coast. I cautioned that we should be open to a lot of possible outcomes, and to realize that prediction of exact snowfall amounts in a given area are very difficult with this sort of storm. Here, I’ll repeat that warning. If you see a big blob of predicted snow on a weather map, you can be pretty sure that if you are within or near that blob, you’ll get snow. But if you look at the exact locations of 12″ snow here, or 6″ snow there, and expect that to be accurate, than please contact me off line, I have nice bridge to sell you.

However, as the storm approaches the predictions get more reliable. In this case, multiple weather models have been in line with each other all along, and the convergence on a big storm with certain characteristics is emerging. The storm will affect land areas staring during the day Friday, and continue through the weekend, depending on your location.

What will happen in Washington DC?

One of the big questions is what will happen in DC. At the moment, some of the standard weather services are predicting five or six inches from between some time Friday and early Sunday in the DC metro. This is conservative, and if you are ramping up your expectations about this storm but are not going to be in the DC area, keep this in mind so later you can be all surprised at a larger amount. But if you are living or working in DC, you need to know that other highly reliable sources, such as the National Weather Service, are suggesting a larger amount.

Sticking with the idea that snowfall prediction is a game of probabilities, I offer this EXPERIMENTAL prediction method showing possible snowfall for a few spots in DC:

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It is pretty obvious how to read this. This information shows that there could be as little as 8 inches across the DC area, but as much as 30 inches. The chance of the snow on the ground adding up to over 18 inches is better than 50-50, meaning that the chances of there being a mere half of this large amount (the 30 inch apocalyptic number) is also 50-50. There is about a 20% chance that the total snow will be less than a foot. This means, of course, that the good money is on a total accumulation of over a foot, possibly a lot over a foot.

In a place like DC, over a foot and over two feet are not that different. Both are city-shutting amounts.

By the way, I’m hearing rumors that in the greater DC area, out in Virginia and such, there was some icing and snow over the last 24 hours that the authorities in charge decided not to plow or treat, so driving conditions in the area are currently very bad. Just rumors, but from credible sources. Maybe the snow plow people are saving up their resources for the big one. (See this!)

Will New York City get much snow?

Yesterday it was looking like New York might get a few inches. However, overnight, various model projections have started to show a big lump of snow on or near New York, suggesting that the storm might have a bigger impact there. Right now, the National Weather Service is saying that there may be 8-12 inches of accumulation in New York.

New York is tricky because it has a strong urban heat island effect. Also, it is adjacent to not one, but two seas, and can be quite windy. Also, while New York has a lot of people in it, and the “Greater New York Area” is huge, overlapping large portions of three states and several counties (at least a dozen), when people go and look at the snowfall in New York City, they look at downtown Manhattan, and that is a tiny area (comparatively) that happens to be situated in a way that makes weather prediction extra hard. It is very common for a substantial snowfall predicted for New York to end up being nothing, or an inch or two. So, expect the unexpected. It is not unreasonable to assume a better outcome for The City than the forecasters suggest. But it may not be wise to rely on that assumption.

Will Boston get much snow?

In a way, Boston is even worse than New York. At the larger scale, Boston has a sort of barrier island, Cape Cod, which can influence some of the weather that comes its way, but Cape Cod is very far away covers only part of the sea in that area. Most storms sneak around it from the northeast. Nor’easters are not named as such for no reason.

Boston is a very small city surrounded by many, many other cities, that are together called “Boston” as in “I lived in Boston” but actually lived in Somerville or Medford or something. Also, Boston is in a basin (the “Boston Basin”) snuggled up to the harbor and Mass Bay, and the highlands rise quickly (but not too much) around it, so it is not at all uncommon for Boston to get one inch of slush proceeded by some rain, while Lexington and Concord (commuting bedroom suburbs of Boston) get several times that.

And, in this case, the northern extent of More’Easter* Jonas is somewhere around Boston but nobody can say for sure yet.

The National Weather Service is suggesting that the worst case, but unlikely, scenario for the Greater Boston Area is 5-6 inches, the most likely 2-3 inches, but with a distinct possibility of zero. The Cape and Islands, and southern Rhode Island and SE Mass may get 6-8 inches. So, for that region, snowfall wise, just a typical winter snow but windy.

Where will the biggest accumulations be?

The biggest accumulations of snow are likely to be inland, at somewhat higher elevations, focusing around a couple of points. Here’s a map I cribbed from Paul Douglas’ blog:

No, wait, here is a more recent updated version, read the discussion below with that in mind:

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Technically, since over a foot of snow is a lot, the answer to this question is “everywhere form Long Island across most of New Jersey, half of Pennsylvania, Much of Virginia and West Virginia, and Maryland.” But, there seems to be two major centroids of heaviest accumulation being predicted, one in New Jersey south of New York City, and the other wet of Washington across Maryland and the Virginia-West Virginia border. But, as I’ve now said a half dozen times or more, these sorts of snowfall projections are notoriously inaccurate at any level of detail. If you live anywhere in the area of this map bounded by the yellow stripe, expect snow. If you are in or near the red and purple zones, there is a chance you will be snowbound. So, run out to the store now with all the other people and get stuff.

The big problem with Jonas may be the wind

But when you do get to the store, if you want to be a True Survivalist, don’t get frozen food or anything that requires electricity to prepare. And get extra batteries. And when you get home, do your laundry so you can get that done before your power goes out. The heavy snow amounts have the potential of knocking down power lines, of course, but there will also be windy conditions during this blizzard, and that will very likely knock a few wires off their poles. If this happens in many places over a large area, a simple outage that could be fixed in a few hours may take much longer. Between roads being closed because of snow and a high demand for repairs, some outages could last much longer than average, maybe even a day or a few days in the worst case. So be ready for that.

Coastal Erosion

My friend Paul Douglas referred to this storm as roughly like a “tropical storm with snow”.* It isn’t really a tropical storm, as he notes, but it is like one in the sense that there will be strong coastal winds and, owing to the winds and very low pressure, a storm surge in some areas.

The storm surge may be most severe between the central New Jersey coast and the Chesapeake. However, the effects of a storm surge are highly local. So, for instance, the Delaware coast, because of the shape of the coast line and its position in the maw of the fetch, may experience high water. Small embayments along the Jersey coast may see very high local surges. There will also be high water in the same areas where Superstorm Sandy rose up to flood New York City and nearby New Jersey, but the height of those waters will not be as bad as during that storm.

The other local phenomenon that determines the severity of a storm surge is, of course, local elevation. Areas with low relief behind the strandline facing the ocean may see several feet of water washing inland, and serious damage to property and natural areas. Places where the land rises quickly behind the beaches will still be affected by wind and spray (expect to see a lot of damaged or dead trees in some areas next spring form the salt) but structures and roads would be less affected. Pay close attention to what your local authorities are saying. At this point, though, the storm surges are expected to cause possibly record-book altering floods. From Paul:

Unseasonably warm water in the Gulf Stream will fuel rapid intensification and pressure falls, a partial vaccuum that will pull air into the core of this developing Nor’Easter, whipping up high winds and pounding surf; the rough equivalent of a wintertime tropical storm (without the warm core). Here’s an excerpt from WXshift: “…On Saturday, powerful winds in excess of 60 mph could whip up waves that could reach 30 feet. As they come ashore, beaches will take a pounding and face widespread erosion. Models also show a current storm surge of around 5 feet coming ashore with Saturday’s high tide. In Cape May, N.J., the current forecast high tide mark on Saturday evening would be the third-highest on record while Atlantic City would come in at 10th in the record books, according to Stephen Stirling at NJ.com. That could push water inland and cause widespread property damage…”

Bottom line: If you live or work in a place within the range of this storm that has been storm-flooded in the past, assume this is a possibility this time.

UPDATE: The storm surge and coastal flooding is starting to ramp up as one of the more likely negative outcomes here. Paul Douglas just sent me these words of warning: “I’m increasingly concerned about the threat of widespread coastal flooding from this super-sized Nor’easter. Blizzard and 50+ mph winds arriving during full moon with sustained onshore winds creating a 4-7 foot storm surge capable of lowland flooding and beach erosion. Facilities that were impacted by Sandy in 2012 may experience problems with this storm.”

The National Weather Service in New York is warning that this may be one of the top five flooding events on record in the area.



So, when Paul made mention of the “Tropical Storm with Snow” to some mutual colleagues, the idea came up that this sort of storm needed a new name (Snowicane, or something like this). I suggested that during the last two decades, there have been more Nor’easters, with more moisture and precipitation, covering more geographical areas (mainly to the south) than in the past. So, maybe the term “More’easter” would be appropriate. Paul anointed the idea, and now you can use the term as well, if you like. I don’t expect the meteorology textbooks to be updated any time soon, but who knows?

A quick word about climate change and El Niño

Yes, this storm is getting its extra moisture and power from climate change with a does of El Niño added in. The driver of this wetness (which will be snowness) is very high sea surface temperatures in the Atlantic. El Niño influences this, but frankly, the sea surface temperatures off shore right now are not a lot different than they were last January, when a huge More’easter blanketed New England in a big pile of snow. This is a global warming enhanced storm.

Does global warming destroy your house in a flood?

Joe and Mary built a house.

They built it on an old flood plain of a small river, though there’d not been a flood in years. This was a 500-year flood plain. Not a very floody flood plain at all.

The local zoning code required that for a new house at their location the bottom of the basement needed to be above a certain elevation, with fill brought in around the house to raise the surrounding landscape. But Joe’s uncle was on the zoning board, and it wasn’t that hard to get a variance. This saved them thousands of dollars, and they built the house without the raised foundation or the fill.

Over the previous fifty years much of the hilly wooded land up river from Joe and Mary’s house had been converted to agriculture. This changed the nature of the flow of rain across the land surface and into the groundwater. It caused the streams to rise more quickly when it rained, rather then slowly over several days fed by springs linked underground to the forest. Downstream, a century ago, engineers built a bridge for the new road, and they put the pilings closer than would be done in modern times. This caused flotsam from spring floodwaters to accumulate at the bridge, backing up water quite a good distance upstream. A large marsh that fed into the river, upstream from Joe and Mary’s house, normally flooded during high water, holding much of the excess. But about a decade ago, Joe’s uncle built a large housing development there, filling the marsh. There was controversy, and it was even covered in the local Pennysaver, but he got the variance. All these things would have made flooding near Joe and Mary’s house to be much worse than otherwise, but that never happened. The 500-year flood zone hadn’t had any 500-year floods in a long time, maybe 500 years.

Meanwhile, while the forest was being cleared, the road and its bridge built, the housing development constructed over the marsh, and Joe and Mary’s house erected, everybody was putting CO2, a greenhouse gas, into the atmosphere. By the last decade or so of the 20th century, there was significant global warming. The increase in global surface temperature was not even; The Arctic warmed more than the rest of the planet. This caused a change in the behavior of the polar jet stream. Instead of occasionally becoming curvy and kinky and slow moving, the jet stream started to do this all the time. Then these waves went “quasi resonant” meaning that the large curves and loops would sit in one place for a long time, weeks or months. Meanwhile the heated up atmosphere started to take on more water vapor. Air that was wet enough to rain in the old days held the vapor longer because of the warmth, but when the super saturated air let the water out in the form of rain or snow, there was a lot of it. Since the weather systems follow the jet stream, they slowed down and would hang around for a long time in one region, raining and raining and raining while elsewhere there would be short term droughts.

One day, at Joe and Mary’s house, it started to rain. It rained four or five inches in a week. The basement got wet. The tomatoes were overwatered, and their leaves cringed. Everybody’s shoes started to smell. The dark, cloudy, wet days produced a sense of ennui.

Then, on the eight day, it really rained. It rained four inches in one day. The groundwater had been saturated, the streams and the river were already high. The torrential rainstorm raised the river to the 100 year flood level. Then to the 500 year flood level. Then a few feet more. Joe’s uncle’s housing development flooded. The bridge with its jam of flotsam became a dam. The water flowed around Joe and Mary’s house, filling the first floor with three feet of dirty water. Snakes took refuge on their roof. Their car floated away.

Eventually the water receded and Joe and Mary’s home was a total loss. The insurance guy had come by to give them the good news. They would receive a full payout for replacement cost of the home. While they were chatting, the insurance guy noted that the flood was caused by the dam of tree branches and house parts down at the bridge. Joe remembered his uncle’s housing development, the controversy about the flood basin, and noted that may have been a problem. The insurance guy agreed. Mary said she had read about how replacing forest with corn fields made runoff worse, so the streams and rivers would flood more. Joe and the insurance guy nodded. Yes, yes, that was a factor too. Nobody mentioned the fact that Joe and Mary had failed to build their home to code, but they were thinking it. They didn’t mention it because, really, they would only have raised the whole house by about two and a half feet, and the flood was higher than that, so what did that matter?

A few days later Joe and Mary were down at the coffee shop to meet a contractor to talk about using their insurance money to build a new house. They were sitting with the contractor going over preliminary plans, but were distracted by two graduate students form the nearby university sitting at the table next to them. They were talking about the flooding. They were talking about how global warming, caused by that CO2 being released into the atmosphere all these years, had caused the flooding. They were talking about the amplification of warming in the Arctic, the jet streams getting curvy and slowing down, the quasi resonant waves and the extra moisture in the atmosphere.

The contractor became annoyed. He had heard about global warming and all that, everybody had. But he also knew that the last four winters were unusually cold and snowy. His cousin had bought a Tesla electric car a few months earlier, and his cousin was an annoying tree hugging hippie. And, he remembered, he had heard an actual climate scientist on the TV the other day saying something about global warming and storms. In fact, he remembered quite clearly what the scientist had said. And now he wanted to say it too.

The contractor turned to the two graduate students, and got their attention. “Couldn’t help overhear your conversation,” he said to them. “But you know, you can’t attribute a single flood, or other weather event, to global warming. This was just a flood.”

Global warming. Dancing backwards and in high heels for more than 20 years.*

Minnesota's Current Weather Disaster — Don't worry we'll be fine.

I woke up this morning to find about a dozen reports on my iPad Damage app indicating trees down and hail damage in many communities from Mankato to Edina, south of the Twin Cities. More of the same. We have been having severe weather for about a month now, or a bit less. One day in late May, Julia and I were taking pictures of people driving too fast through the lake that formed in front of our house form a major downpour. Early in that storm we witnessed a ground strike not too far away. A short while after that an ambulance came screaming by our house, coming from the direction of the ground strike to the hospital just south of us. Later we heard on the news that a woman at a little league game (which, frankly, should have been cancelled) was struck and transported to the hospital … that was certainly her. This morning, Mankato was flooded, a day or two ago a woman was rescued from her car that was eventually swept away by a river that does not normally exist. Flooding up on the Canadian Border has been epic. The entire state is under a Meteorological Siege.

Not exactly a Turn Round Don't Drown situation, but perhaps a Slow Down So As To Not Crack Your Engine Block situation .
Not exactly a Turn Round Don’t Drown situation, but perhaps a Slow Down So As To Not Crack Your Engine Block situation .
Yet, somehow, CNN has not taken notice.

I believe that what is happening here is an expanded, intensified version of what we usually get around this time of year. The Norther Plains has storms in the late Spring and early Summer for various meteorological reasons. But this Spring, the jet stream continues to experience it’s kinkyness, not the good kind of kinkyness, and we are having stalled weather systems. So, instead of having a storm front move through the area every few days, we have a big huge stormy thing hanging over us for weeks on end.

This is a similar phenomenon, most likely, to what brought epic floods to Central Europe, the UK, Calgary, and Colorado over the last two years. But, since we have no mountains to speak of and the state is full of more swamp and pond than arroyo and river, we don’t have the same kind of result. The rain that fell over the last 24 hours in southern Minnesota, falling in Colorado’s front range would have wiped out towns and people would be missing for days. Here, we have different results. Same weather phenomenon (more or less) likely caused by the same changes to the environment resulting form global warming (most likely) but spread out a bit in time and space so it becomes, rather than a single big huge national news story, this string of little local news stories (listed by day of month for June):

The interaction between the nature of events and the nature of news journalism certainly is interesting. We couldn’t stay out of the news when the Polar Vortex was visiting. Now, we are being ignored in all our glorious wetness. That is reasonable … so far this weather has not caused the death and destruction of epic flooding in mountain areas, and we are lucky that we’ve not had significant tornadoes here – the twisters are staying to the south of us, just. But it is interesting that we suffer the weather of countless tiny drops Minnesota style. In silence. With the occasional stern look. We will be making some hot dish now, out of season, but it is our comfort food. Don’t worry, we’ll be fine.


Here’s a few tweeted pics from the NWS Twin Cities:

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Levees and the National Flood Insurance Program (NAP)

The National Academies Press of the United States has recently released a report that will be of interest to those of you concerned with climate change (which better be every one of you dammit!). The report talks about increasing floods due to weather whiplash and sea level rise due to glacial melting (and subsidence), mainly in relation to the levees program and insurance, but also more generally. Here’s a small excerpt to give you a flavor:

Community flood risk scenarios will continue to evolve as change occurs. Climate change will have a variety of regional impacts, and the geographic location of a community will affect how changing conditions affect risk. Some areas will have more droughts, some will have more frequent floods, and others will have more intense floods. Research to understand these hydrologic changes is ongoing (NRC, 2011, 2012a). A recent special report of the Intergovernmental Panel on Climate Change (IPCC, 2012) indicates a likely increase in many regions of the frequency of heavy precipitation events, and when coupled with increasing vulnerability presents a myriad of challenges for coping with climate-related disastersIPCC. Galloway (2009) cites 11 major international studies conducted from 1987 to 2002 that all predict significant climate change–induced hazards, including increased flooding, higher mean atmospheric temperatures, higher global mean sea levels, increased precipitation, increased strength of storms, more energetic waves, storm surges that reach further inland, undercapacity of urban sewer- age and drainage systems, increased vulnerability of port cities, and disproportionate impacts on disadvantaged population segments (Galloway, 2009). The rise in sea level and the increase in storm surge due to climate change puts many coastal areas at risk from intensified flooding (NRC, 2010).

Hirsch and Ryberg (2012), in examining trends in annual floods at 200 stream-gauge sites in the United States, found that , while there appeared to be no strong statistical evidence for flood magnitudes increasing with increasing global mean carbon dioxide concentration, there were differences in flood magnitudes among the four quadrants of the conterminous United States (Figure 6-8). They indicate that the attention should be paid to the effects of changes in the relative “importance of the role of snowpack and rain on snow events.” Raff (2013) suggests that the increase in magnitude of floods in the northeastern and midwestern United States (Figure 6-9, Upper Right), may have consequences in the Upper Mississippi, Ohio, and Missouri watersheds (Hirsch and Ryberg, 2012; Raff, 2013).

The Draft National Climate Assessment, issued in January 2013 by the National Climate Assessment Develop- ment Advisory Committee, begins with the statement:

Climate change is already affecting the American people. Certain types of weather events have become more frequent and/or intense, including heat waves, heavy downpours, and, in some regions, floods and droughts. . . . The largest increases have occurred in the Northeast, Midwest, and Great Plains, where heavy downpours have exceeded the capacity of infrastructure such as storm drains, and have led to flooding events and accelerated erosion.

The report goes on to point out the increasing vulnerability to flooding of those in floodplains and coastal areas

You can buy the report for a mere $53, or download it for free. (Downloading from the NAP involves signing in and stuff, but it is pretty easy, though at the moment their server is running a bit slow since they just publicized the report and everybody wants a copy of it.)

Go HERE to get the report.

Welcome Spring Storm Season

This picture, from a current (as of this writing) accuweather forecast page, is an excellent illustration of what happens here in the upper Midwest the spring.


The overall pattern of movement of air masses at the continental scale is west to east, with extra moist and extra warm air secondarily moving north from the Gulf of Mexico, and cool and usually dry air coming form the Northwest (not shown here but note the “blizzard” part) and with dry Pacific/Rocky Mountain air coming from the west. The main energy flow to keep an eye on is that coming from the Gulf.

There is a rule of thumb you can apply here….

Continue reading Welcome Spring Storm Season