bluewave

First time since 1875 that NYC only had a T of snow through mid-January following 10+ in mid-December. Time Series Summary for NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending. Rank Ending Date Total Snowfall Dec 10 to Dec 20 Dec 21 Jan 14 1 1948-12-20 21.1 5.7 2 1960-12-20 16.6 2.0 3 1916-12-20 13.8 0.7 4 1904-12-20 13.3 10.7 5 1945-12-20 12.1 3.5 6 2009-12-20 10.9 2.3 7 2020-12-20 10.5 T 8 1917-12-20 10.1 2.0 - 1874-12-20 10.1 T

We are actually doing better here relative to the means than areas closer to the Northern Tier. NYC is still ahead of Grand Rapids in snowfall through January 13th. Bismarck has gone the latest ever without a reading below 0°.Their average first below 0° date since 1980 is December 1st. So this would be like NYC not going below freezing until January. Time Series Summary for Bismarck Area, ND (ThreadEx) Click column heading to sort ascending, click again to sort descending. Rank Ending Date Lowest Min Temperature Oct 1 to Jan 13 Missing Count 1 2021-01-13 0 0 2 1955-01-13 -6 0 3 2012-01-13 -7 0 - 2003-01-13 -7 0 - 1983-01-13 -7 0 - 1908-01-13 -7 0 - 1891-01-13 -7 0

The Pacific Jet continues to make headlines.

Coming up on the 5th anniversary of one of the greatest snowstorms of all time.

The Northern Tier will eventually cool with the more Niña-like -EPO -PNA -AO pattern.

Warmest start to January on record for Bismarck, ND at +18.5. Time Series Summary for Bismarck Area, ND (ThreadEx) Click column heading to sort ascending, click again to sort descending. Rank Ending Date Mean Avg Temperature Jan 1 to Jan 12 Missing Count 1 2021-01-12 30.8 0 2 2012-01-12 29.2 0 3 1990-01-12 27.5 0 4 2002-01-12 27.1 0 - 1987-01-12 27.1 0 5 1983-01-12 26.9 0

It appears that the new GFS v16 scheduled to go operational in February has fixed the cold bias. https://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/

https://www.sciencedaily.com/releases/2019/08/190801120209.htm US infrastructure unprepared for increasing frequency of extreme storms August 1, 2019 American Geophysical Union Current design standards for United States hydrologic infrastructure are unprepared for the increasing frequency and severity of extreme rainstorms, meaning structures like retention ponds and dams will face more frequent and severe flooding, according to a new study. Extreme weather events are on the rise, but U.S. water management systems use outdated design guidelines. New research, published in the AGU journal Geophysical Research Letters, analyzed data from multiple regions throughout the U.S. and found the rising number of extreme storms combined with outdated building criteria could overwhelm hydrologic structures like stormwater systems. The new study is particularly timely in light of recent storms and flash floods along the East Coast. "The take-home message is that infrastructure in most parts of the country is no longer performing at the level that it's supposed to, because of the big changes that we've seen in extreme rainfall," said Daniel Wright, a hydrologist at the University of Wisconsin-Madison and lead author of the new study. Engineers often use statistical estimates called IDF curves to describe the intensity, duration, and frequency of rainfall in each area. The curves, published by the National Oceanic and Atmospheric Administration (NOAA), are created using statistical methods that assume weather patterns remain static over time. "Design engineers at cities, consulting companies, and counties use this for different purposes, like infrastructure design management, infrastructure risk assessment and so forth. It has a lot of engineering applications," said Amir Aghakouchak, a hydrologist at the University of California, Irvine who was not involved with the new study. But climate change is causing extreme rainfall events to occur more often in many regions of the world, something IDF curves don't take into account. One measure of extreme rainfall is the 100-year storm, a storm that has a one percent chance of happening in a given year, or a statistical likelihood of happening once in 100 years on average. Wright and his colleagues wanted to know how existing IDF curves compare with recent changes in extreme rainfall. They analyzed records from more than 900 weather stations across the U.S. from 1950 to 2017 and recorded the number of times extreme storms, like 100-year storms, exceeded design standards. For example, in the eastern United States, extreme rainstorm events are happening 85 percent more often in 2017, than they did in 1950. In the western U.S., these storms are appearing 51 percent more often now than they once did. The scientists found that in most of the country the growing number of extreme rainstorms can be linked to warming temperatures from climate change, although natural events, such as El Niño, also occasionally affect the Southeast's climate. By comparing the number of storms that actually happened against the number predicted by IDF curves, the researchers also showed the potential consequences for U.S. infrastructure. In some regions, for example, infrastructure designed to withstand extreme rainstorms could face these storms every 40 years instead of every 100 years. "Infrastructure that has been designed to these commonly-used standards is likely to be overwhelmed more often than it is supposed to be," Wright said. The researchers hope the findings will encourage climate scientists, hydrologists, and engineers to collaborate and improve U.S. hydrologic infrastructure guidelines. "We really need to get the word out about just how far behind our design standards are from there they should be," Wright said. Story Source: Materials provided by American Geophysical Union. Original written by Abigail Eisenstadt. Note: Content may be edited for style and length. Journal Reference: Daniel B. Wright, Christopher D. Bosma, Tania Lopez‐Cantu. U.S. Hydrologic Design Standards Insufficient Due to Large Increases in Frequency of Rainfall Extremes. Geophysical Research Letters, 2019; DOI: 10.1029/2019GL083235 https://www.nytimes.com/interactive/2020/06/29/climate/hidden-flood-risk-maps.html Nearly twice as many properties may be susceptible to flood damage than previously thought, according to a new effort to map the danger. Across much of the United States, the flood risk is far greater than government estimates show, new calculations suggest, exposing millions of people to a hidden threat — and one that will only grow as climate change worsens. That new calculation, which takes into account sea-level rise, rainfall and flooding along smaller creeks not mapped federally, estimates that 14.6 million properties are at risk from what experts call a 100-year flood, far more than the 8.7 million properties shown on federal government flood maps. A 100-year flood is one with a 1 percent chance of striking in any given year. The federal government’s flood maps guide where and how to build, whether homeowners should buy flood insurance, and how much risk mortgage lenders take on. If the new estimates are broadly accurate, it would mean that homeowners, builders, banks, insurers and government officials nationwide have been making decisions with information that understates their true physical and financial risks. Numerous cities nationwide — as diverse as Fort Lauderdale, Fla., Buffalo, N.Y., and Chattanooga, Tenn. — show the startling gap in the risks. In Chicago alone, 75,000 properties have a previously undisclosed flood risk. And minority communities often face a bigger share of hidden risk. “Millions of home and property owners have had no way of knowing the significant risk they face,” said Matthew Eby, founder and executive director of the First Street Foundation, a group of academics and experts based in New York City who compiled the data, creating a website where people can check their own address.

Long Island used to get normal snowfall before the mid1990s. But since then, we switched to all or nothing mode. More frequent very high or very low snowfall winters. Fewer closer to the mid range. https://www.bnl.gov/weather/4cast/MonthlySnowfall.htm

This is the composite for the last 10 La Niña events to reach 6” or more in NYC during January and February. That’s why we need that -PNA trough out West to pull back off the West Coast at storm time. Like I said in the post above, relevant details like that may not be known for a while yet. And there may have probably been lesser than 6” storms that had more leeway.

https://news.stanford.edu/2021/01/11/climate-change-caused-one-third-historical-flood-damages/ In a new study, Stanford researchers report that intensifying precipitation contributed one-third of the financial costs of flooding in the United States over the past three decades, totaling almost $75 billion of the estimated $199 billion in flood damages from 1988 to 2017. The research, published Jan. 11 in the journal Proceedings of the National Academy of Sciences, helps to resolve a long-standing debate about the role of climate change in the rising costs of flooding and provides new insight into the financial costs of global warming overall. “The fact that extreme precipitation has been increasing and will likely increase in the future is well known, but what effect that has had on financial damages has been uncertain,” said lead author Frances Davenport, a PhD student in Earth system science at Stanford’s School of Earth, Energy & Environmental Sciences (Stanford Earth). “Our analysis allows us to isolate how much of those changes in precipitation translate to changes in the cost of flooding, both now and in the future.” The global insurance company Munich Re calls flooding “the number-one natural peril in the U.S.”However, although flooding is one of the most common, widespread and costly natural hazards, whether climate change has contributed to the rising financial costs of flooding – and if so, how much – has been a topic of debate, including in the most recent climate change assessments from the U.S. government and the Intergovernmental Panel on Climate Change. At the crux of that debate is the question of whether or not the increasing trend in the cost of flooding in the U.S. has been driven primarily by socioeconomic factors like population growth, housing development and increasing property values. Most previous research has focused either on very detailed case studies (for example, of individual disasters or long-term changes in individual states) or on correlations between precipitation and flood damages for the U.S. overall. In an effort to close this gap, the researchers started with higher resolution climate and socioeconomic data. They then applied advanced methods from economics to quantify the relationship between historical precipitation variations and historical flooding costs, along with methods from statistics and climate science to evaluate the impact of changes in precipitation on total flooding costs. Together, these analyses revealed that climate change has contributed substantially to the growing cost of flooding in the U.S., and that exceeding the levels of global warming agreed upon in the United Nations Paris Agreement is very likely to lead to greater intensification of the kinds of extreme precipitation events that have been most costly and devastating in recent decades. “Previous studies have analyzed pieces of this puzzle, but this is the first study to combine rigorous economic analysis of the historical relationships between climate and flooding costs with really careful extreme event analyses in both historical observations and global climate models, across the whole United States,” said senior author and climate scientist Noah Diffenbaugh, the Kara J Foundation Professor at Stanford Earth. “By bringing all those pieces together, this framework provides a novel quantification not only of how much historical changes in precipitation have contributed to the costs of flooding, but also how greenhouse gases influence the kinds of precipitation events that cause the most damaging flooding events,” Diffenbaugh added. The researchers liken isolating the role of changing precipitation to other questions of cause and effect, such as determining how much an increase in minimum wage will affect local employment, or how many wins an individual player contributes to the overall success of a basketball team. In this case, the research team started by developing an economic model based on observed precipitation and monthly reports of flood damage, controlling for other factors that might affect flooding costs like increases in home values. They then calculated the change in extreme precipitation in each state over the study period. Finally, they used the model to calculate what the economic damages would have been if those changes in extreme precipitation had not occurred. “This counterfactual analysis is similar to computing how many games the Los Angeles Lakers would have won, with and without the addition of LeBron James, holding all other players constant,” said study co-author and economist Marshall Burke, an associate professor of Earth system science. Applying this framework, the research team found that – when totaled across all the individual states – changes in precipitation accounted for 36 percent of the actual flooding costs that occurred in the U.S. from 1988 to 2017. The effect of changing precipitation was primarily driven by increases in extreme precipitation, which have been responsible for the largest share of flooding costs historically. “What we find is that, even in states where the long-term mean precipitation hasn’t changed, in most cases the wettest events have intensified, increasing the financial damages relative to what would have occurred without the changes in precipitation,” said Davenport, who received a Stanford Interdisciplinary Graduate Fellowship in 2020. The researchers emphasize that, by providing a new quantification of the scale of the financial costs of climate change, their findings have implications beyond flooding in the U.S. “Accurately and comprehensively tallying the past and future costs of climate change is key to making good policy decisions,” said Burke. “This work shows that past climate change has already cost the U.S. economy billions of dollars, just due to flood damages alone.” The authors envision their approach being applied to different natural hazards, to climate impacts in different sectors of the economy and to other regions of the globe to help understand the costs and benefits of climate adaptation and mitigation actions. “That these results are as robust and definitive as they are really advances our understanding of the role of historical precipitation changes in the financial costs of flooding,” Diffenbaugh said. “But, more broadly, the framework that we developed provides an objective basis for estimating what it will cost to adapt to continued climate change and the economic value of avoiding higher levels of global warming in the future.”

This is the composite for the last 10 La Niña events to reach 6” or more in NYC during January and February. That’s why we need that -PNA trough out West to pull back off the West Coast at storm time. Like I said in the post above, relevant details like that may not be known for a while yet. And there may have probably been lesser than 6” storms that had more leeway.

I will be happy If we can get that -PNA trough off the West Coast for at least a few days. The 360 hr EPS is taking a step in the right direction. But you can see how important that ridge over the Plains was for the 3-22-18 event when the -PNA trough pulled back.

I think we’ll need that -PNA trough over the Western US to back off a bit from what the week 2 EPS has. In March 2018 it pulled just off the West Coast with higher heights over Southern Canada. This allowed a ridge in Minnesota for separation between systems.

The fact that NYC is yet to drop below 20° highlights how little Arctic air has been around. This is only the 5 year that NYC has gone this far into the cold season without one. For Boston it’s only the 6th year not to drop below 16. At BTV it’s only the 10th year not to reach 0 yet. Time Series Summary for NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending. Rank Ending Date Lowest Min Temperature Oct 1 to Jan 12 Missing Count 1 1975-01-12 26 0 2 2013-01-12 22 0 3 2021-01-12 20 1 - 2002-01-12 20 0 - 1932-01-12 20 0 Time Series Summary for Boston Area, MA (ThreadEx) Click column heading to sort ascending, click again to sort descending. Rank Ending Date Lowest Min Temperature Oct 1 to Jan 12 Missing Count 1 2002-01-12 22 0 2 2007-01-12 20 0 3 1975-01-12 17 0 4 2021-01-12 16 1 - 1955-01-12 16 0 - 1929-01-12 16 1 Time Series Summary for Burlington Area, VT (ThreadEx) Click column heading to sort ascending, click again to sort descending. Rank Ending Date Lowest Min Temperature Oct 1 to Jan 12 Missing Count 1 2007-01-12 5 0 2 2002-01-12 3 0 3 2016-01-12 2 0 - 2000-01-12 2 0 5 2021-01-12 1 1 - 2012-01-12 1 0 - 1987-01-12 1 0 - 1955-01-12 1 0 - 1932-01-12 1 0 - 1924-01-12 1 0

I wonder if the ridge bridge over the top of the -PNA trough today is a result of the EPS seeing continuing influence from the SSW? This raises the question of whether the EPS will correct from what it’s showing now in early February. We really need a strong -EPO -AO connection to counteract the influence of the -PNA.

The latest EPS weeklies keep the window of opportunity open from January 25th to Feb 1st. Jan 11-18 Jan 18-25 Jan 25-Feb 1 Feb 1 - Feb 8

It’s as if the historic December 2015 +13.3 reset the whole winter climate warmer. NYC Dec 15....+13.3 Jan 16....+1.9 Feb 16....+2.4 Dec 16....+0.8 Jan 17....+5.4 Feb 17....+6.3 Dec 17....-2.5 Jan 18.....-0.8 Feb 18....+6.7 Dec 18....+2.6 Jan 19....-0.1 Feb 19....+0.9 Dec 19....+0.8 Jan 20....+6.5 Feb 20....+4.8 Dec 20.....+1.7 Jan 21.....+3.6...so far

It’s ironic that we may get our first -EPO drop since mid-December as the PNA is turning negative just after the 20th. This can often happen as the ridge pulls back to Aleutians and higher heights extend toward Alaska. So it looks like the PNA drop which the models had originally forecast near the start of February is moving up by 6-10 days.

You area has been warm rather than mild. POU is +5.1 through the 10th. The departures are being driven by the warm minimums. POU is +2.3 for the average daily max departure and a whopping +7.8 for the minimums. NYC is +3.6 with a +2.7 max and a +4.5 min departure. BTV is even more extreme at +6.8. They are +2.9 on the max and a +10.7 on the minimum. The more impressive warm departures have been the further north you go.

The Pacific Jet continues on steroids. Looks like a 220KT max today. So no surprise that we will continue with this mild airmass.

It’s always a challenge guessing when snowfall will start up again following a long break. It will be a month this week since the area near the coast saw accumulating snows. Snowfall return intervals after past pauses have been highly variable.

The all or nothing snowfall pattern continues for North America. Rollercoaster ride hitting record highs in October followed by record lows in November. Quick rise in mid-December then a fall around Christmas. Now the snow extent is near the bottom of the list for January 9th.

You have to look at it through the lens of the pattern that we have at the time. When we have a record breaking Pacific Jet pattern, we need all the help that we can get from Pacific blocking. So in the case this December, it took the poleward extension of the ridge through the EPO region to the North Pole to get us the snowstorm. But during other years with a less amped up Pacific Jet, we have gotten by with just the +PNA and +EPO and -AO. That’s why the +EPO during El Niño’s can be OK. The North Pacific Jet weakens while the STJ becomes the strongest. This helps carve out the trough over the SE US and allows the 50/50 low and high over New England hold its ground with a +EPO and weaker Pacific Jet. So +EPO during an El Niño isn’t the liability it can be with a La Niña. That’s why our best La Niña seasons like 95-96 had such frequent blocking near Alaska. While great El Niño’s had the STJ running the show with -AO and +PNA. NYC 2 greatest snowstorms 27.5”....Jan 22-23 -16 super El Niño +EPO 2016 01 20 43.26 2016 01 21 31.89 2016 01 22 48.24 2016 01 23 71.40 2016 01 24 71.56 2016 01 25 14.98 2016 01 26 29.36 2016 01 27 55.70 2016 01 28 160.56 2016 01 29 177.26 26.9”.....Feb 11-12-06....La Niña -EPO 2006 02 09 -53.06 2006 02 10 -93.77 2006 02 11 -74.28 2006 02 12 -35.51 2006 02 13 -69.84 2006 02 14 -214.72 2006 02 15 -288.49 2006 02 16 -309.34 2006 02 17 -330.28 2006 02 18 -298.10 Late November 95 into April 96 historic snowfall pattern for a La Niña