Feb 032012
 

Jared N asked a great question yesterday. Basically, he was asking how long this current dry spell will last and what will the fire outlook be? La Nina and the general cold of the Pacific Ocean is driving our weather pattern and it doesn’t look like a big change is on the way

ENSO (El Nino Southern Oscillation) Outlook from the International Research Institute for Climate and Society - January 19, 2012

ENSO (El Nino Southern Oscillation) Outlook from the International Research Institute for Climate and Society - January 19, 2012

El Nino and La Nina are the warm and cold episodes for the sea surface temperatures in the equatorial Pacific. El Nino usually indicates a cool wet pattern for the Southwest. La Nina usually means a warm dry winter for the Southwest. In the chart above, most of the models show that La Nina will hang on at least through Spring. The March-April-May (MAM) data point shows the temperature anomaly just crossing above -0.5 degrees C. One half of a degree anomaly is the demarcation of La Nina or El Nino.

La Nina Impacts- CLIMAS - University of Arizona

La Nina impacts CLIMAS - University of Arizona

With El Nino, the storm track is typically right across the southern United States. With La Nina, the jet stream and storm track stay to the north. Since our last storm in December, we experienced this nearly exact situation. With La Nina predicted to stay in tact, the outlook is for more of the same. While it seems to me that the Climate Prediction Center’s 3-month outlook looks nearly the same for any situation, it actually applies now. Warm and dry conditions are forecast for the next 3 months. The would indicate a potentially bad fire season. However, a single errant storm could dump a bunch of snow and get us back to normal.

3 month temperature out look from the Climate Prediction Center

3 month temperature out look from the Climate Prediction Center

3 month precipitation outlook from the Climate Prediction Center

3 month precipitation outlook from the Climate Prediction Center

 

 Posted by at 7:09 am
Jan 112012
 

The Pacific Decadal Oscillation is a climate variability pattern that cycles over decades. An indicator of the phase is sea surface temperature. In the warm phase the eastern Pacific Ocean is warm and the western Pacific Ocean is cool. In the cool phase, the western Pacific is warm and the eastern Pacific is cool. Right now, the eastern Pacific is very cool. Also, notice the equatorial Pacific is cool with La Nina in place.

Pacific sea surface temperature anomaly on January 9, 2012. NOAA

Pacific sea surface temperature anomaly on January 9, 2012. NOAA

The Pacific Decadal Oscillation Index represents the degree of PDO variability. With the current cool conditions, the November 2011 measurement of the PDO Index is the lowest it has been since 1961. The PDO INdex in November was -2.33. It has been mostly negative since 2005.

PDO Index based on data from Joint Institute for the Study of the Atmosphere and the Ocean at the University of Washington

PDO Index based on data from Joint Institute for the Study of the Atmosphere and the Ocean at the University of Washington

While a number of factors affect Arizona’s climate, a cool or negative PDO Index is typically associated with drier than normal conditions across the southern United States. This seems to fit our current dry pattern.

The chance for snow on Sunday is evaporating.

 Posted by at 7:09 am
Jan 082012
 

The National Weather Service office in Flagstaff produced two very nice documents about 2011. One is a review of top weather events in 2011. It’s a pdf of a Powerpoint slide set. The second is their standard text review of 2011. Here they are:

Top 10 Weather Events in 2011

2011 Year in Review

Both pdfs are worth seeing. The only point I would like to make about the year is that overall it was below average on temperature. Sure, it was dry, but we typically don’t hear about things being colder than average.

La Nina drove the dry weather. La Nina and a cold Pacific Ocean could have contributed to the cooler weather. Also, throughout the year the solar cycle continued to underperform to NASA’s models. The Sun has been very dim.  Half a degree of temperature swing may not seem like much. The Arizona Daily Sun didn’t report on the cold year in their 2011 Year in Review: Drought in Flagstaff ends article. Keep in mind that this average temperature included one of Flagstaff’s hottest Augusts on record. By comparison, the global temperatures change by a similar amount during El Nino events. That is typically news.

UAH Global Temperature Update for Dec. 2011

UAH Global Temperature Update for Dec. 2011

It seems to me that half of a degree merits pointing out. Consider it done.

New weather prediction instrument added!!!

My family gave me an “Admiral Fitzroy’s Storm Glass” for Christmas. You can view it next to my Shark Oil Barometer.  It has a similar reported behavior. I think it is still getting acclimated. Wikipedia has Storm Glass page. About.com has a Fitzroy’s Storm Glass page. I will be modifying the barometer webpage to include a Storm Glass section. For now, here is how it should work:

  • If the liquid in the glass is clear, the weather will be bright and clear.
  • If the liquid is cloudy, the weather will be cloudy as well, perhaps with precipitation.
  • If there are small dots in the liquid, humid or foggy weather is expected.
  • A cloudy glass with small stars indicates thunderstorms.
  • If the liquid has small stars on sunny winter days, then snow is coming.
  • If there are large flakes throughout the liquid, it will be overcast in temperate seasons or snowy in the winter.
  • If there are crystals at the bottom, this indicates frost.
  • If there are threads near the top, it will be windy.

It didn’t seem to change as we had the windy system move through last night. But, we will see what it does in the future. I had to move the barometer out of the window. The storm glass should not be placed in the direct sunlight. I’m not sure where I will leave it.

Stu's weather equipment including Admiral Fitzroy's Storm Glass

Stu's weather equipment including Admiral Fitzroy's Storm Glass

 Posted by at 6:22 am
Nov 192011
 

Does it seem like we have had a wet fall? It has been. It has also been similar to last fall. In the chart below, I have plotted the daily and cumulative precipitation for the months of September through November for the last 4 years.

Fall Precipitation for  2008-2011

Fall Precipitation for 2008-2011 - Source data from the National Weather Service preliminary monthly climate data

The daily precipitation is in the bar chart at the bottom, and uses the right axis.  The cumulative precipitation is in the line chart and uses the left axis. The falls of 2008 and 2009 were considerably drier. Both the falls of 2010 and 2011 have seen the onset of La Nina. This could be a reason. Fall of 2008 brought the emergent warming of the equatorial Pacific Ocean with El Nino setting in during 2009. Since late 2009, the equatorial Pacific Ocean has cooled with back to back La Nina events.

I also took a look at temperatures for the last four falls. Other than this fall appearing cooler than the last 3, I struggled to find a meaning sign of a trend. With that said, this month to date is more than 4 degrees below normal. October was 0.7 above normal and September was 1.4 above normal.

Cumulative departure from normal daily temperatures, Falls 2008-2011

Cumulative departure from normal daily temperatures, Falls 2008-2011

The chances of added precipitation for the rest of the month keep popping in and out of the forecast models. The GFS and NoGAPs models are not consistent with each other. GFS this morning is showing a snowy Thanksgiving.

 Posted by at 7:00 am
Jul 252011
 

We’ve been hearing a lot about the heat wave in the Midwest and it’s expansion to the East Coast. Meanwhile, Flagstaff’s temperatures have been dead on the average for the month to date. The graphic from HAMWeather.com shows temperature records for the last week. New high temperature records we set in a broad fashion across the United States. Just a note that some low temperature records were set in the West.

HAMweather Climate Center - Record Events for The Past Week - Continental US

HAMweather Climate Center - Record Events for The Past Week - Continental US

The rest of the world isn’t exactly following the North American heating trend. Below is a graphic of global surface temperatures for 2009-2011. Notice that global temperatures are lower now than in the last couple years.

Global satellite temperatures - AMSU-A

Global satellite temperatures - AMSU-A

The real drivers for the lower global temperature are ocean temperatures.

8 day forecasted average temperature anomaly. R. Maue - Florida State University

8 day forecasted average temperature anomaly. R. Maue - Florida State University

Europe, Africa, North America, Asia, Australia and Antarctica are all showing up as mostly above normal. But, by and large, the world’s oceans are cooler than normal. Interesting situation.

For Flagstaff, if we can get the daily heating from mostly cloudless morning skies, we should see some nice monsoonal activity this week.

 Posted by at 3:33 am
Jan 232011
 

There has been much hype about last year being one of the warmest on record. If you look at the data that hasn’t been “corrected” to fit a model, 1934 was the warmest on record. 1998 was the second warmest and 2010 was below 2010. However, most of the anthropogenic global warming supports have corrected their data over time and have declared 2010 the warmest on record. They have also deleted the Medieval Warm Period. If you delve into the IPCC reports over the years, this is clear. But, there is quite a buzz building about the future.

NASA recently reduced their forecast for the current solar cycle, solar cycle 24. The current revision moves the peak level to 59 sunspots. A team of Russian scientists have been predicting aggressive cooling due to reduced solar activity for quite some time. NASA has been playing catch-up and the continuous reduction in their sunspot forecast is show below. There are two solar minimum in “recent history” that they are comparing this too.

NASA's historic predictions for Solar Cycle 24 keep dropping

NASA's historic predictions for Solar Cycle 24 keep dropping

First, the Dalton Minimum is associated with Solar Cycles 5 and 6 from 1798 to 1823. During the Dalton Minimum these solar cycles had sunspot peaks of 49.2 and 48.7 sunspots. At a prediction of 59, Solar Cycle 24 is close to this range. There are very few temperature records that go back to this time period, but 3 stations did show downward temperature trends. Oberlach in Germany showed an average temperature decline of 2 degrees Celsius during this time frame. The famous “Year Without a Summer” happened during this time frame. The Year Without a Summer was probably also affected by a major volcanic eruption.  Also, winters were characterized by people being able to skate on the Thames River. The winter of 1813-1814 was the 4th coldest on the Central England temperature record. London had great Christmas snow during this time frame, too:

Christmas Snow in London

Christmas Snow in London

The other major solar minium in recent history is called the Maunder Minimum. The Maunder Minimum is associated with the coldest part of the Little Ice Age. The Maunder Minimum lasted from 1645 to 1715. During the Maunder Minimum, lower temperatures were noted across Europe. Given that Central England just had their coldest December in 400 years, it should be noted that their coldest winter in the last 500 years occurred during the Maunder Minimum and is know as the Great Frost of 1709. The London area recorded temperatures of -12C that winter.

New Scientist ran a good article last summer, What’s Wrong With The Sun (New Scientist, 14 June 2010). If you want something with deeper technical information, Are Cold Winters in Europe Associated with Low Solar Activity (Environmental Research Letters, 5, 14 April 2010), provides details on how this is manifested and the actual data to support the theory. Average temperatures dropped by as much as 2 degrees celsius for the Maunder Minimum. This would wipe out all of the warming of the last century.

Other than our New Years cold wave, we have had a nice, warm winter. That hasn’t been the case elsewhere. The global average temperature has dropped since the El Nino aggressively switched to a La Nina. England, Europe and Australia have all been cold. The climate conference in Cancun in December was greeted with the coldest December temperatures ever recorded.

Personally, I think the long lingering snow and ice of the last few winters, and the associated damages, are a result of the long solar minimum and the current weak solar cycle. But, what really got me started was this recent video blog post from Joe Bastardi at Accuweather:

So, what will we be facing? We should be prepared for colder temperatures and the associated effects. Will it last two solar cycles like the Dalton Minimum, or 60 years like the Maunder Minimum? That is the question.

One more note. Friday saw the setting of new record lows for International Falls, Minnesota. At -46F, it was the 5th coldest temperature ever recorded at International Falls since 1897.

 Posted by at 6:26 am
Dec 102010
 

Sorry folks, I’ve been in Japan for the last week and out of the loop as a result. Sorry the storm didn’t materialize while I was gone. It looks like there will be a couple chances for white stuff in the near future.

The normally conservative AccuWeather forecast has snow forecasted for the week of Christmas. Not just for a single day that week, but the entire week. In fact, they see the snow starting next Thursday and continuing through December 24. To some extent, his is reinforced by the GFS model which shows a strong system on a southerly track hitting Arizona on December 23. The Flagstaff forecast from the National Weather Service has a chance of snow next Thursday.

But, the high pressure off the coast of Southern California has been quite strong and unmovable of late. I am highly skeptical. But, my T-model shows a similar possibility for Christmas Week.

 Posted by at 6:39 am
Nov 132010
 

If you have your own rain gauge, I strongly encourage you to supply your data to Rainlog.org.

<from Rainlog.org> Rainlog.org is a cooperative rainfall monitoring network for Arizona. Data collected through this network will be used for a variety of applications, from watershed management activities to drought planning at local, county, and state levels. Precipitation amounts are highly variable across Arizona due to topography and seasonal weather patterns. This is especially true during the monsoon season, when thunderstorms can produce heavy rainfall that is very localized.

Here is a graphic of the data for the Flagstaff Area in October 2010. Their monthly report is attached below. You can see the variability that makes this such a great service. If you don’t have a rain gauge, you can look on this site and find someone near you. This can help you decide if you need to water your plants, or not.

October 2010 Rainfall - Flagstaff

October 2010 Rainfall - Flagstaff

Rainlog Climate Summary for October 2010

Sorry for the delay in sending the October summary. November snuck up on us.

October was full of weather surprises including a record number of tornadoes and unusually wet conditions across the northern half of Arizona. Several strong low pressure systems moved through the Southwest during October, bringing unsettled weather, cooler temperatures and widespread precipitation to parched areas of northern Arizona. Several of these storm systems dropped one-day totals of over an inch of rain in the Kingman and Flagstaff areas.

Rainloggers in northern Arizona reported two-day totals in excess of 3 inches from large thunderstorm complexes that moved from north to south on October 4th and 5th. October 5th was the busiest day with the development of several severe thunderstorms and eight confirmed tornadoes that touched down from Cottonwood to Flagstaff, destroying several homes and flattening over 5,000 acres of forest.

October precipitation amounts were two to four times greater than average across the northwest quarter of the state. The southern half of Arizona has seen far less precipitation with most locations reporting only 50-75% of normal rainfall.

October’s wild, wet weather gave way to a dry and warm weather pattern in early November. This most likely will be the main story for the rest of the winter. A strong La Nina event is underway in the Pacific Ocean and is expected to steer winter storms north, away from the Southwest, leaving us with unusually dry weather and the threat of rapidly emerging short-term drought conditions.

 Posted by at 6:02 am
Nov 112010
 

I just think we have a great group of dedicated folks at our local Flagstaff National Weather Service. They have pulled together a very nice review of Possible La Nina Impact on Northern Arizona. I encourage you to give their website a visit and watch the presentation. It has some great comments and covers the exceptional variability we can have in Northern Arizona. They review October 1 to April 15 precipitation for every year since 1950 with a La Nina.

Going back to my Fall and Winter Outlook(Fall Outlook, Winter Outlook) posts, (I mentioned La Nina, the associated negation Pacific Decadal Oscillation(PDO) and another feature, the Atlantic Multidecadal Oscillation(PDO)). I have included the Wikipedia links for those terms if you want to learn more. Currently, La Nina is in a cool or negative phase. The PDO is in a cool or negative phase. And, the AMO is in a warm or positive phase.  La Nina’s are more frequent during cold PDO phases.

Historically, the AMO was in a warm phase from 1901-1963 and from 1995-present. The AMO was in its cool phase from 1964 until 1994. Graphically, I have overlayed this on the NWS presentation below.

AMO + La Nina Precipitation Effects for Flagstaff

AMO + La Nina Precipitation Effects for Flagstaff

Taking the average of the AMO warm phase precipitation amounts yields 7.59 inches for October-April, with a standard deviation of 2.95 inches. For the AMO cool phase, the average precipitation was 12.6 inches with a standard deviation of 4.7 inches. These are fairly large differences with minimal overlap at the first standard deviation.

I think the obvious trend for La Nina with a warm AMO is for a significantly greater chance of a dry winter. With that said, 2007-2008 has some similarities to this year, and was near the historic average since 1950. For now, I am sticking with my previous forecasts. If cooler than normal temperatures become the rule, I may change my mind.

For the near term, we will continue to have fronts move through the area on occasion. Also, temperatures will continue their cooler trend. This week will pretty much be the model for the rest of the month, at least through Thanksgiving. Will it snow on Thanksgiving?

 Posted by at 4:41 am
Oct 092010
 

Winter is just around the corner. What will it be like? If you want to cut to the chase, scroll down to the bottom. If you want some interesting details, read on.

There are two major long term ocean temperature effects that play key roles in global weather situations. If you read my blog regularly, I refer to the Pacific Decadal Oscillation(PDO) as a key player in our weather. Another, that I don’t mention as often is the Atlantic Multidecadal Oscillation(AMO).

The AMO and PDO are long term cycles.  Both take several decades to oscillate from warm to cold and back again to warm. These compare to the relatively short term El Nino Southern Oscillation (ENSO). ENSO includes La Nina, El Nino, and La Nada. These cycles tend to shorter cycles of several months.

In the graphs below, the positive (red) portions of the graph are the warm phases and indicate positive temperature anomalies in the the northern Pacific and Atlantic Oceans.

Pacific Decadal Oscillation Index - University of Washington

Pacific Decadal Oscillation Index - University of Washington

Atlantic Multidecadal Oscillation - Wikipedia from NOAA data

Atlantic Multidecadal Oscillation - Wikipedia from NOAA data

Notice the time scales are different in the two graphs. Here are current shorter term graphs of both indices.

Atlantic Multidecadal Oscillation since 1981

Atlantic Multidecadal Oscillation since 1981

Pacific Decadal Oscillation since 1981

Pacific Decadal Oscillation since 1981

I find that most experts believe that the PDO shifted to a cool or negative phase in 1998 and remains there today. Also, as I have read more most believe the AMO shifted to a warm phase in 1995. So, who cares? You should. The NorthAtlantic and North Pacific have very strong influences on our weather patterns.

Here is a 2003 article from McGabe, et alPacific and Atlantic Ocean influences on multidecadal drought frequency in the United States. It’s an interesting article that helps explain the drought we have seen for the last decade or so. This chart provides a summary of the outcome of their research.

Drought frequency (in percent of years) for positive and negative regimes of the PDO and AMO. (A) Positive PDO, negative AMO. (B) Negative PDO, negative AMO. (C) Positive PDO, positive AMO. (D) Negative PDO, positive AMO.

Drought frequency (in percent of years) for positive and negative regimes of the PDO and AMO. (A) Positive PDO, negative AMO. (B) Negative PDO, negative AMO. (C) Positive PDO, positive AMO. (D) Negative PDO, positive AMO.

The 4 maps represent that possible combinations of positive and negative AMO’s and PDO’s. The red areas show a greater than 30 percent likelihood of a drought. The blue areas show a lesss than 20 percent chance of drought. For the current combination of positive AMO and negative PDO, we would look to image D in the lower right hand corner of this chart. This is the region with the highest likelihood of drought.

So, back to my analog year for this year. The AMO was very positive at this time of year. The PDO shifted from very positive to negative. While the chart above doesn’t show the most recent months, this is very similar to this year. The AMO is currently very positive and the PDO has aggressively shifted to negative. Some say that this PDO shift is the most aggressive ever recorded.

The outlook is for the AMO to stay positive, or warm, the PDO to stay negative and a strengthening La Nina (cool phase ENSO). Here is the sea surface temperature anomaly outook  for December 2010 to February 2011 from the International Research Institute for Climate and Society.

Global sea surface temperature anomaly outlook for December 2010 to February 2011

Global sea surface temperature anomaly outlook for December 2010 to February 2011

The current La Nina is forecasted to continue to deepen through the winter. This is a major La Nina event that should cause global temperatures to be significantly cooler this winter. This is apparently the most aggressive shift and deepest La Nina since 1955.

El Nino Southern Oscillation Index (ENSO) forecast (IRI)

El Nino Southern Oscillation Index (ENSO) forecast (IRI)

So, I continue to see this winter being quite dry. I am still up in the air about temperature. December 1998 to February 1999 precipitation in Flagstaff was 1.18 inches, 5.74 inches below normal. This winter could be on par with those amounts.

Keep in mind that last year at this time, the forecast was for a strengthening La Nina and a very dry winter. That obviously didn’t happen. There is still lots of time for something to change.

 Posted by at 6:30 am
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