December 2015: Wettest Month on Record

Oneiric 3

I think this deserves a thread of its own. Just looking solely at the IMT 11 station mean, it is clear now that this month (December 2015) will finish even wetter than the historic wet month of November 2009.

This chart shows November '09 rainfall totals compared with this December totals so far up to the 29th, and even though we still have two days to go, this month has already proved to be wetter at 9 of the 11 stations used in the index, bringing the mean total up to almost 20 mm above the mean total of that infamous month in 2009. All data is from Met Eireann and averages are based around the 1981-2010 climate period:



Will be interesting to see how other station data compares which I'll do once this month is complete. But whichever way, this month likely to go down in weather history as the wettest on record in many places.

Gaoth Laidir

I am still pretty convinced that El Niño has had a hand in this. I know you have found no statistical correlation with winters in Ireland, but breaking it down to sub-seasonal scales I think the pattern that El Niño promotes in the Pacific does lend to setting up a particular pattern in the Atlantic too.

The ridging in the west and east of the North American continent has to have an impact in the Rossby pattern downstream. You have found very little correlation with El Niño and the NAO during December, but I think NAO is not the be-all and end-all of it. NAO has been positive over the past month, but the particular orientation of the Atlantic trough has led to this conveyor belt of rain systems. I reckon this trough has been locked in place by the pattern over NA, which in turn has strong links to El Niño.



November 2009 saw a similar setup, albeit with an El Niño in earlier stages of development. But it was similar, and also occured during an El Niño. Only two datapoints, I know, and you admit that we need more to make a proper statistical analysis. I know there is not much correlation with surface pressure, but that may not be relevant in the orientation of the strong southwesterly conveyor belt. How do precipitation patterns look? Is there any correlation? That would be an interesting insight.

sryanbruen

Well Cork Airport is up 396.5mm now - very scary if you ask me of it going this high

Oneiric 3

Gaoth Laidir wrote: »

I know there is not much correlation with surface pressure, but that may not be relevant in the orientation of the strong southwesterly conveyor belt. How do precipitation patterns look? Is there any correlation? That would be an interesting insight.

You can check the stats here yourself:
http://climexp.knmi.nl/start.cgi?id=someone@somewhere

As I am sure I said a while back, patterns do conform somewhat in areas directly affected by El Nino - during an El Nino, but way too much going in between here and there to be able to conclude that certain patterns are favoured over the N.Atlantic & Ireland/Europe. I certainly can't see much evidence from the statistics and practical examples I looked at, but am open to being convinced otherwise.

ABC101

Speaking to a American colleague today.... he mentioned there is flooding on the Mississippi river up by St Louis.

Normally flooding occurs in the spring....when the snows start melting etc... but to have flooding in December is rather rough.

CNN had this article here 30th December 2015 By Ashley Fantz and Ben Brumfield, CNN

http://edition.cnn.com/2015/12/30/us/severe-weather-us/

A 24-mile stretch of I-44 is closed from Interstate 270 in St. Louis County to the Highway 100 exit in Gray Summit in Franklin County, authorities said. Many people are in hotels and all are encouraged to stay off the roads.

Throughout the country's midsection about 400 river gauges are over flood stage, with around 45 showing major flooding, the National Weather Service said.

Many of those are in or around St. Louis. Some rivers and streams have already crested, and some haven't yet, like the Mississippi. It is expected to reach its peak late Wednesday or early Thursday in Missouri along with other area streams.

Missouri will still have "major to historic river flooding through early next week," the National Weather Service's St. Louis office said. "Record crests expected on area rivers the next several days."

"We've never seen water this high," Missouri Gov. Jay Nixon told CNN's "New Day." "The Meramec River is going to be 4 feet over its historic level."

At its peak, the Mississippi should be at its highest level ever, Nixon said, beating the highest level of the great flood of 1993.

"That's why we've got a state of emergency," he said. But it is expected to drain off rapidly, so he is hopeful the cleanup phase will begin soon.

I cannot scientifically say....it is definitely El Nino... but El Nino must be having some effect on the weather we are having this year.

Oneiric 3

ABC101 wrote: »

El Nino must be having some effect on the weather we are having this year.

This would need to be quantified though. During the cold, dry winter of 2009/2010 here in Ireland and the UK, El Nino and its effects were the big buzz phrases at the time, and in the years following.

I took a quick look at the wettest winter months in Northern Ireland, and of the top 20, only 4 occurred while the NINO index was significantly positive (> 1.0) 1958, 1966, 1988 & 1995; of the top 5, there is only one instance (Feb 1966).

Correlation value between the top 20 wettest NI winter months on record, and the NINO index is 0.05446396, with a P-Value of 0.5741; very poor on both counts.

sryanbruen

I would say El Nino is the main cause of warm Winters here, I totally disagree with colder Winters here - 2009 / 10 was just because of the jet stream and the pressure centres etc. Winter 2006 / 07 was another great example. Cumbria in England has recorded 3 of its greatest floods during 3 El Ninos (2004 / 05, 2009 / 10, 2015 / 16)

ABC101

Well... if it is not El Nino...its La Nina... and if its not either of them.... its the number of Sunspots.... suns magnetic cycle and so on and on ....

We basically can't say for sure. There is most probably a link... but by how much.... by what quantification etc?

Science will just have to continue trying to prefect the model of global climate etc.

Oneiric 3

Final totals at the reporting Met Eireann synoptic stations. An extraordinary month for rain.




Expressed as percentage of averages, Roches Pt values topped the table at 341.6%, followed by Oak Park's 324%. Lowest percentage values were Mace Hd's 151.0% and Newport's 176.4%

All data C/O Met Eireann.

sryanbruen

In parts of Florida, it was also their wettest December on record largely due to storm Desmond which affected here also.

Stinicker

Forest fires in Indonesia were outputted the same Co2 in two weeks as the entire German economy did in a year.

http://www.wri.org/blog/2015/10/indonesia%E2%80%99s-fire-outbreaks-producing-more-daily-emissions-entire-us-economy.

The scale of environmental and ecological devastation wrath by these fires seems to be hugely ignored or brushed under the carpet. People in Manila nearly 1,000kms away had to wear breathing masks due to the pollution unleashed by those fires burning rainforest and ancient bog in Indonesia.

You just cannot emit so much pollution in the air in such a short timeframe and not expect global ramifications.

Gonzo

hard to believe my neck of the woods has the lowest rainfall in Ireland, goes to show just how much it rained in the west and south with those massive month totals.

Xenji

We have averaged about 285mm of rain in Castlebar for the last two Januarys, if we get similar this month we would be looking at over 1000mm of rain since the start of November.

sryanbruen

Was 402.2mm at Cork Airport the highest monthly total for a lowland station in Ireland on record? By lowland, I mean no:

*Lake (Cloone Lake)
*Mountainous
*Valley (Maam Valley)

etc

ABC101

Came across this article on the NASA website... about El Nino..

I found it fascinating... one of which was 20inches difference in sea level height between East and West Pacific!!

So I thought I should share it here with you ... just in case you missed it.


Link here..

http://www.nasa.gov/press-release/nasa-examines-global-impacts-of-the-2015-el-ni-o

A Still-Growing El Niño Set to Bear Down on U.S.


The current strong El Niño brewing in the Pacific Ocean shows no signs of waning, as seen in the latest satellite image from the U.S./European Ocean Surface Topography Mission (OSTM)/Jason-2 mission.


El Niño 2015 has already created weather chaos around the world. Over the next few months, forecasters expect the United States to feel its impacts as well.


The latest Jason-2 image bears a striking resemblance to one from December 1997, by Jason-2's predecessor, the NASA/Centre National d'Etudes Spatiales (CNES) Topex/Poseidon mission, during the last large El Niño event. Both reflect the classic pattern of a fully developed El Niño. The images can be viewed at:

http://sealevel.jpl.nasa.gov/elnino2015/index.html

The images show nearly identical, unusually high sea surface heights along the equator in the central and eastern Pacific: the signature of a big and powerful El Niño. Higher-than-normal sea surface heights are an indication that a thick layer of warm water is present.


El Niños are triggered when the steady, westward-blowing trade winds in the Pacific weaken or even reverse direction, triggering a dramatic warming of the upper ocean in the central and eastern tropical Pacific. Clouds and storms follow the warm water, pumping heat and moisture high into the overlying atmosphere. These changes alter jet stream paths and affect storm tracks all over the world.


This year’s El Niño has caused the warm water layer that is normally piled up around Australia and Indonesia to thin dramatically, while in the eastern tropical Pacific, the normally cool surface waters are blanketed with a thick layer of warm water. This massive redistribution of heat causes ocean temperatures to rise from the central Pacific to the Americas. It has sapped Southeast Asia’s rain in the process, reducing rainfall over Indonesia and contributing to the growth of massive wildfires that have blanketed the region in choking smoke.


El Niño is also implicated in Indian heat waves caused by delayed monsoon rains, as well as Pacific island sea level drops, widespread coral bleaching that is damaging coral reefs, droughts in South Africa, flooding in South America and a record-breaking hurricane season in the eastern tropical Pacific. Around the world, production of rice, wheat, coffee and other crops has been hit hard by droughts and floods, leading to higher prices.
In the United States, many of El Niño’s biggest impacts are expected in early 2016. Forecasters at the National Oceanic and Atmospheric Administration favor an El Niño-induced shift in weather patterns to begin in the near future, ushering in several months of relatively cool and wet conditions across the southern United States, and relatively warm and dry conditions over the northern United States. The latest El Niño forecast from NOAA’s Climate Prediction Center is at:

http://www.cpc.ncep.noaa.gov/

While scientists still do not know precisely how the current El Niño will affect the United States, the last large El Niño in 1997-98 was a wild ride for most of the nation. The “Great Ice Storm” of January 1998 crippled northern New England and southeastern Canada, but overall, the northern tier of the United States experienced long periods of mild weather and meager snowfall. Meanwhile, across the southern United States, a steady convoy of storms slammed most of California, moved east into the Southwest, drenched Texas and -- pumped up by the warm waters of the Gulf of Mexico -- wreaked havoc along the Gulf Coast, particularly in Florida.


"In 2014, the current El Niño teased us -- wavering off and on," said Josh Willis, project scientist for the Jason missions at JPL. "But in early 2015, atmospheric conditions changed, and El Niño steadily expanded in the central and eastern Pacific. Although the sea surface height signal in 1997 was more intense and peaked in November of that year, in 2015, the area of high sea levels is larger. This could mean we have not yet seen the peak of this El Niño."


During normal, non-El Niño conditions, the amount of warm water in the western equatorial Pacific is so large that sea levels are about 20 inches (50 centimeters) higher in the western Pacific than in the eastern Pacific. "You can see it in the latest Jason-2 image of the Pacific," said Willis. "The 8-inch [20-centimeter] drop in the west, coupled with the 10-inch [25-centimeter] rise in the east, has completely wiped out the tilt in sea level we usually have along the equator."


The new Jason-2 image shows that the amount of extra-warm surface water from the current El Niño (depicted in red and white shades) has continuously increased, especially in the eastern Pacific within 10 degrees latitude north and south of the equator. In the western Pacific, the area of low sea level (blue and purple) has decreased somewhat from late October. The white and red areas indicate unusual patterns of heat storage. In the white areas, the sea surface is between 6 and 10 inches (15 to 25 centimeters) above normal, while in the red areas, it is about 4 inches (10 centimeters) above normal. The green areas indicate normal conditions. The height of the ocean water relates, in part, to its temperature, and is an indicator of the amount of heat stored in the ocean below.


Within this area, surface temperatures are greater than 86 degrees Fahrenheit (30 degrees Celsius) in the central equatorial Pacific and near 70 degrees Fahrenheit (21 degrees Celsius) off the coast of the Americas. This El Niño signal encompasses a surface area of 6 million square miles (16 million square kilometers) -- more than twice as big as the continental United States.


While no one can predict the exact timing or intensity of U.S. El Niño impacts, for drought-stricken California and the U.S. West, it’s expected to bring some relief.


"The water story for much of the American West over most of the past decade has been dominated by punishing drought," said JPL climatologist Bill Patzert. "Reservoir levels have fallen to record or near-record lows, while groundwater tables have dropped dangerously in many areas. Now we’re preparing to see the flip side of nature’s water cycle -- the arrival of steady, heavy rains and snowfall."


In 1982-83 and 1997-98, large El Niños delivered about twice the average amount of rainfall to Southern California, along with mudslides, floods, high winds, lightning strikes and high surf. But Patzert cautioned that El Niño events are not drought busters. "Over the long haul, big El Niños are infrequent and supply only seven percent of California’s water," he said.
"Looking ahead to summer, we might not be celebrating the demise of this El Niño," cautioned Patzert. "It could be followed by a La Niña, which could bring roughly opposite effects to the world’s weather."


La Niñas are essentially the opposite of El Niño conditions. During a La Niña episode, trade winds are stronger than normal, and the cold water that normally exists along the coast of South America extends to the central equatorial Pacific. La Niña episodes change global weather patterns and are associated with less moisture in the air over cooler ocean waters. This results in less rain along the coasts of North and South America and along the central and eastern equatorial Pacific, and more rain in the far Western Pacific.


El Niño events are part of the long-term, evolving state of global climate, for which measurements of sea surface height are a key indicator.
For an animation of the evolution of the 2015 and 1997 El Niños, visit:

https://sealevel.jpl.nasa.gov/elnino2015/2015-animated.gif

For more information on how NASA studies El Niño, visit:

http://climatesciences.jpl.nasa.gov/enso

To learn more about NASA’s satellite altimetry programs, visit:

http://sealevel.jpl.nasa.gov

http://www.nasa.gov/earth

Alan Buis
Jet Propulsion Laboratory, Pasadena, Calif.
818-354-0474
Alan.buis@jpl.nasa.gov

sryanbruen

It was also confirmed as the UK's wettest month on record today