Wednesday, September 29, 2010

La Niña Influence on U.S. Winter Weather

Headline: La Niña to Influence our Winter Weather Pattern.

As noted in the last posting in the SNR Climate Corner Blog (see link below)
we are currently seeing La Niña conditions in the Pacific Ocean. It is currently a moderate strength La Niña, and it is expected to become a strong La Niña by mid-Winter 2010-11. The attached figure shows the generalized influences on weather and climate in North America for both an El Niño and a La Niña.

Unlike an El Niño which results in a very wet pattern for the southwestern U.S. and Gulf region, the La Niña phase sees the storm track deflected well north to the Pacific Northwest and toward Alaska resulting in very dry and warm conditions across the southwest and Gulf region. Cold air, with much below normal temperatures builds in Canada during the typical La Niña and warm air with above normal temperatures builds across the southern Plains.

La Niña winters in Nebraska are most known for very large swings in temperature as the two air masses, (colder than normal to the north and warmer than normal to the south) battle it out for supremacy. So, don't be surprised if we see some days this winter with record warmth as well as some days with record cold temperatures throughout the region. With drier than normal conditions across the Gulf and a storm track well off to our northwest, Gulf moisture (the primary ingredient for heavy snowfall in our area) should be restricted in our area this coming Winter 2010-11.

Link to La Niña forecast:
http://snrclimatecorner.blogspot.com/2010/09/la-nina-returning-for-winter-2010-11.html),

Link to animation of Ocean surface temperatures (showing the current La Niña):
http://www.elnino.noaa.gov/

Tuesday, September 28, 2010

La Niña Returning for Winter 2010-11

Headline: La Niña Returns
We are currently in a La Niña phase for the Pacific Ocean. Last Winter we were in an El Nino phase and we transitioned into the La Niña phase earlier this Summer. This oscillation back and forth is known as the El Nino Southern Oscillation (ENSO).

The attached graph shows the predictions from over a dozen computer models for the upcoming Winter 2010-11 through Spring 2011. The three letters on the bottom axis are clusters of three months (SON = September, October, November for example). The left axis shows the forecast temperature anomalies (with negative numbers indicating La Niña and positive numbers indicating El Nino.

All of the models show the La Niña peaking in intensity (most negative values on the left axis) in early to mid Winter. Indications are that this La Niña will be one of the more intense ones and it will also quickly begin to disappear by mid-Spring (with several models indicting neutral conditions, i.e. neither La Niña or El Nino by next Summer).

La Niñas can have a dramatic impact on our winter weather on the Plains and will be illustrated in the next BLOG posting at our site.

Tuesday, September 21, 2010

Lincoln, NE, 90 Degree Heat in 2010


September 20, 2010 marked the 42nd day that the temperature in Lincoln hit 90 F or higher.


The "Average" or "normal" number of days reaching 90 F in Lincoln, NE is 42 days.


Therefore, 2010 has been exactly "normal" for heat wave days of temperatures reaching 90 F or higher in Lincoln.
More information on "heat wave days" can be found at the following link: http://www.lincolnweather.org/lincoln-heat-waves.html


Friday, September 17, 2010

Jan-Aug. 2010 Globe Warmest on Record



Headline: "January 1-August 31, 2010 was Warmest on Record for the Globe".

From NCDC: Year-to-date (January–August)
The January–August 2010 map of temperature anomalies shows above-average temperatures over most of the globe's surface area. The warmest surface temperature anomalies for the year-to-date period occurred over Canada, the northern U.S., southern Greenland, Africa, southwest Asia, and the tropical North Atlantic Ocean. Cool temperature anomalies were present across central Asia, non-equatorial eastern Pacific Ocean, and the southern oceans. The global land and ocean surface combined temperature for January–August 2010 tied with 1998 as the warmest such period on record with temperatures 0.67°C (1.21°F) above the 20th century average. Global ocean surface temperatures were the second warmest January–August on record, behind 1998, with temperatures 0.53°C (0.95°F) above the 20th century average. The average global land surface temperature for the period was 1.04°C (1.87°F) above the 20th century reference period and ranked as the warmest January–August on record.

Thursday, September 16, 2010

Global Climate Summary - August 2010



Headline: August 2010 Global Temperature 3rd Highest on Record (131 years of data).

Note the table below that I crated which has all of the monthly Global Averages for Year 2010.

From NCDC: August 2010 Global Highlights
The combined global land and ocean surface temperature for August 2010 was the third warmest on record at 16.2°C (61.2°F), which is 0.60°C (1.08°F) above the 20th century average of 15.6°C (60.1°F). August 1998 is the warmest August on record and 2009 is the second warmest.


The August worldwide land surface temperature was 0.90°C (1.62°F) above the 20th century average of 13.8°C (56.9°F)—the second warmest August on record, behind 1998.


The worldwide ocean surface temperature was 0.50°C (0.90°F) above the 20th century average of 16.4°C (61.4°F) and tied with 1997 as the sixth warmest August on record.

The combined global land and ocean average surface temperature for June–August 2010 was the second warmest on record, behind 1998, at 16.2°C (61.3°F), which is 0.64°C (1.15°F) above the 20th century average of 15.6°C (60.1°F).

Here is a listing of the monthly global temperature rankings for Year 2010:
Global Data Rankings
1880-2010:(131 years)
Jan. 2010: 4th Warmest (Much Above Normal)
Feb. 2010: 5th Warmest (Much Above Normal)
Mar. 2010: #1 Warmest on Record (Much Above Normal)
Apr. 2010: #1 Warmest on Record (Much Above Normal)
May 2010: #1 Warmest on Record (Much Above Normal)
June 2010: #1 Warmest on Record (Much Above Normal)
July 2010: 2nd Warmest on Record (Much Above Normal)
Aug. 2010: 3rd Warmest on Record (Much Above Normal)
Year 2010: (Jan.-Aug.): #1 Warmest on Record

Monday, September 13, 2010

Lincoln, NE: Last 90F Temperature of 2010?

Sunday, September 12 saw the temperature soar to 92 F in Lincoln, NE.
This was only 4 degrees below the record high for the date of 96 F.

Although this may seem late in the season to have a temperature of 90F or higher, it is in fact near the normal date for the last 90F or higher in Lincoln. The average last 90 F in Lincoln is September 18.

The latest 90F or higher temperature in Lincoln occurred on October 20, 1947.

So, the odds are this was probably not our last 90 F or higher temperature for the year.

Finally, how does our total so far of temperatures reaching or exceeding 90 F compare to normal? As of September 12, 2010, Lincoln has experienced 41 days with temperatures reaching 90 F or higher. The normal is 42 days, so this year with 41 days is almost exactly normal at this point.

The year with the most number of days 90 F or higher? 1936 with 82 days!
The year with the least number of days 90 F or higher? 1889 with only 7 days!


For more information about Lincoln's heat waves and hot temperatures check out:
http://www.lincolnweather.org/lincoln-heat-waves.html
.

Friday, September 10, 2010

Summer 2010 U.S. Climate Summary


Headline: It was the 4th warmest on record for the U.S. Summer 2010.
Climatologists and Meteorologists use June 1 through August 31 to define Summer and not the astrological dates of June 20,21,or 22 for the start of Summer and September 20, 21 or 22 for the end of Summer.
From NOAA: U.S. Temperature Highlights – Summer (June through August)


It was the fourth warmest summer on record in the United States. Three climate regions had temperatures in the top five: the Southeast (warmest), the Central (third warmest) and the Northeast (fourth warmest).

Abnormal warmth dominated much of the east, where a record warm summer occurred in Rhode Island, New Jersey, Delaware, Maryland, Virginia, North Carolina, Tennessee, South Carolina, Georgia and Alabama. Nineteen other states experienced “much above normal” average temperatures.

Several cities broke summer temperature records, including New York (Central Park); Philadelphia; Trenton, N.J.; Wilmington, Del.; Tallahassee, Fla. (tied); and Asheville, N.C.
U.S. Precipitation Highlights – Summer (June through August)
The summer storm pattern brought significant precipitation to the Upper Midwest. Wisconsin had its wettest summer on record, 6.91 inches above average. Several states in the region had a top-10 wettest summer: Michigan and Iowa (third wettest), Illinois and Nebraska (sixth), South Dakota (ninth) and Minnesota (10th). The East North Central climate region had its second wettest summer on record, and the nationally averaged precipitation was above average.
A persistent high pressure system and the lack of any significant tropical weather during the summer months contributed to below average precipitation in much of the Southeast and Mid-Atlantic. Long-term dryness in the Mid-Atlantic led to the development of severe drought in parts of Virginia, Maryland and West Virginia.
Heavy rainfall during the summer months across the Upper Midwest helped diminish rainfall deficits from the first five months of the year.

Thursday, September 9, 2010

August 2010 Statewide Climate Rankings

Headlines:
August 2010: Nebraska was warmer than normal
95th coldest or 21st warmest on record with 116 years of data

U.S. August 2010: 7th warmest August on record.

Summary From NOAA/NCDC:
Temperature Highlights - August
Persistently strong high pressure continued to dominate the weather pattern in the U.S. during August 2010. This was the 7th warmest August on record with a temperature that was 2.2°F above the long-term average.
The majority of the U.S. had above average temperatures during August. Florida, Louisiana (tied) and Tennessee (tied) each had their second warmest August on record. Fourteen other states had an August temperature among their warmest ten percent. No state experienced an average temperature significantly below its long term average.
Regionally, the Southeast had its third warmest August on record, while it was the seventh warmest in the South and the eighth warmest in the East North Central. Of the nine climate regions in the contiguous U.S., only the West and Northwest observed near normal August temperatures.

Friday, September 3, 2010

Summer 2010 Lincoln was Warmer than Normal


"A Warmer than Normal Summer for Lincoln Nebraska in 2010"

The Summer of 2010 (June 1-August 31, 2010) was the 30th warmest out of 124 years of data for Lincoln, NE.

The graph on this page shows the normal or average high temperature with a red curve and the normal or average low temperature with a blue curve. The top of each black vertical line is the high temperature for the day and the bottom of each black vertical line is the low for the day.
For example, the black vertical line for August 12, 2010 shows a high temperature of 100 F well above the normal of 88 F (the red curve) and the low for the day was 67 F and was just a few degrees above the normal of 65 F (the blue curve)

Thursday, September 2, 2010

Summer 2010: Top Ten Wettest for Lincoln



Lincoln Nebraska Summer 2010 Precipitation.

Summer 2010: June 1 - August 31 (see below for why we use these dates)

The precipitation total for Lincoln, NE in Summer 2010 was 18.54 inches and this was the 6th wettest summer on record for Lincoln with 124 years of data going back to 1887.

With 2.53 inches of precipitation falling in Lincoln on September 1, the total for the June 1-September 1, 2010 time period was 21.07 inches and was the 4th wettest for that time period.

The attached map shows that Lincoln and much of eastern Nebraska was in a region of excessive precipitation during the Summer of 2010.

Why do we use June 1-August 31 as "Summer"?

Climatologists and meteorologists define Summer as June 1-August 31 and not the commonly used astronomical definition of June 21 to September 21. In fact the beginning and ending dates of Summer using the astronomical method varies from year to year with Summer starting as early as June 20 and as late as June 23. This makes it difficult to compare one summer to the next so we use the June 1 to August 31 dates for the beginning and end of summer.