A Recap of the 2011 Drought

2011 will go down in the record books as being one of the hottest and driest summers in history for the Southern Plains.  Extremely hot and dry conditions plagued the region, with numerous all-time high temperature records broken, along with record drought conditions across much of the region.  The prolonged heat and drought had drastic effects on the region's agriculture and farming communities, as well as causing numerous wild fires, and heat related illnesses and deaths.  Click on images and graphs for a larger view.

Jump to information about:  Rainfall Deficits and Drought Progression Temperature Effects on the Drought Summer 2011 Records Effects of the Drought
       
 What led to the drought?  Current Drought Information Outlook for 2012  

 


Rainfall Deficits and Drought Progression

Most will remember the summer months of 2011 as being very dry, but the drought conditions actually started during the previous fall season in 2010.  Below are bar graphs showing the 2010, 2011, and 2012 monthly precipitation (in blue), along with the average expected amounts (in red) for both Tulsa, OK and Fort Smith, AR.  Average data was taken from 1981 - 2010.

Tulsa, OK Fort Smith, AR
 Tulsa rain graph  Fort Smith rain graph

As the bar graphs show, below average precipitation was already occurring at both Tulsa and Fort Smith during the fall and winter months of 2010.  Once spring of 2011 arrived, above average rainfall fell across the area.  However, by June 2011, precipitation was almost non-existent, leading to extreme drought conditions across the area through the summer.  There was a bit of relief in mid-August, when a storm system moved into the area bringing a prolonged period of rainfall.  The Tulsa area received 4.50" of rainfall over this period, while Fort Smith received 2.06".  Most of this rainfall fell over a 3-day period (Aug 10-12), leaving the rest of the month mostly dry.  Unfortunately, this heavy rainfall was not enough to improve the drought conditions across the area.  Below normal rainfall countinued into the fall, followed by a very wet November.  This helped to alleviate the drought for December and January, especially across the eastern half of the state.

Below is a set of maps depicting the progression of the drought from October 2010 - December 2011.  During the fall of 2010, precipitation across the Southern Plains started to dwindle, creating D0 and D1 (abnormally dry and moderate drought) conditions across the state of Oklahoma.  The below average rainfall continued into the winter months of 2011, intensifying the drought to D2 level (severe drought) by early February.  Spring 2011 brought some relief across the eastern half of the state, with above normal rainfall in April and May; however, the western half of the state received little rain, increasing the drought level there to worsen to D3, and even the highest, D4 levels (extreme and exceptional drought).  The months of June and July brought very little rain to much of the Southern Plains, expanding the D4 (exceptional drought) levels eastward into central and eastern Oklahoma by August.  These exceptional drought levels persisted through much of the fall of 2011, with improvement across eastern Oklahoma during December 2011 and January 2012.

Month

Observed Precipitation
(click imager for larger view)
Percent of Normal Precipitation
(click imager for larger view)
Drought Monitor
(click imager for larger view)
October 2010 October 2010 rain October 2010 percent of normal October 2010 drought monitor
October 5, 2010
November 2010 November 2010 rain November 2010 percent of normal  November 2010 drought monitor
November 2, 2010
December 2010 December 2010 rain December 2010 percent of normal December 2010 drought monitor
November 30, 2010
January 2011 January 2011 rain January 2011 percent of normal  January 2011 drought monitor
January 4, 2011
February 2011 February 2011 rain February 2011 percent of normal February 2011
February 1, 2011
March 2011 March 2011 rain March 2011 percent of normal  March 2011 drought monitor
March 1, 2011
April 2011 April 2011 rain Apri 2011 percent of normal April 2011 drought monitor
March 29, 2011
May 2011  May 2011 rain  May 2011 percent of normal May 2011 drought monitor
May 3, 2011
June 2011  June 2011 rain  June 2011 percent of normal June 2011 drought monitor
June 7, 2011
July 2011  July 2011 rain  July 2011 percent of normal July 2011 Drought Monitor
July 5, 2011
August 2011 August 2011 rain August 2011 percent of normal August 2011 drought monitor
August 2, 2011
September 2011  September 2011 rain  September 2011 percent of normal September 2011 drought monitor
September 6, 2011
October 2011  October 2011 rain  October 2011 percent of normal October 2011 drought monitor
October 4, 2011
November 2011  November 2011 rain  November 2011 percent of normal November 2011 drought monitor
November 1, 2011

 December 2011

 December 2011 rain  December 2011 percent of normal
 December 2011 drought monitor
November 29, 2011
 January 2012  January 2012 rain  January 2012 percent of normal

January drought monitorJanuary 3, 2012

 

 January 1, 2011 - December 14, 2011
 (observed and depature from normal)

2011 oberseved rain 2011 departure from normal rainfall drought monitor legend
 


Temperature Effects on the Drought Conditions

Conditions across the area were also very hot during the summer months, only serving to further aggravate the existing drought.  Below are graphs showing the 2010 and 2011 monthly average temperature (in blue), along with the expected monthly average temperature (in red) for both Tulsa, OK and Fort Smith, AR.  Average data was taken from 1981 - 2010.

Tulsa, OK Fort Smith, AR
 Tulsa temperature graph  Fort Smith Temperature graph

As the line graphs show, the fall and winter season of 2010, along with the spring of 2011, were fairly close to normal.  However, once we entered the 2011 summer months of June, July, and August, the temperature rose to between 5°F and 10°F above normal.  The extremely hot temperatures also served to draw any remaining moisture out of the soil, exaggerating the drought conditions.  Further, these hot temperatures quickly evaporated any rain that did occur.


Summer 2011 Records

Many of the extreme heat and drought records set during the 1980s, 1950s, and even "Dust Bowl" years of the 1930s, were broken during the months of June, July, and August for both Tulsa, OK and Fort Smith, AR.

Tulsa, OK:

Tulsa, OK

Monthly Average Temperature Departure from 1981-2010 Normal
Rank Record Monthly Average High Temperature Normal Monthly High Temperature Monthly Average Low Temperature Normal Monthly Low Temperature
June 2011 84.4°F +6.8°F #2 hottest 85.8°F 1911 95.6°F 87.5°F 73.2°F 67.7°F
July 2011 90.9°F +8.0°F #2 hottest 91.7°F 1980 103.0°F 93.1°F 78.7°F 72.7°F
August 2011 87.6°F +5.4°F #5 hottest 91.0°F 1936 99.9°F 93.1°F 75.3°F 71.3°F
Summer 2011 87.7°F +6.8°F #2 hottest 88.0°F 1980 99.5°F 91.3°F 75.8°F 70.6°F

 

Tulsa, OK  Rainfall  Departure from 1981-2010 Normal  Rank  Record
June 2011 1.47"  -3.25" #10 driest 0.27" 1933
July 2011 0.36" -3.00" #14 driest Trace 1935
August 2011 5.76" +2.86" #14 wettest 0.00" 1896
Summer 2011 7.59"  -3.39" #32 driest  2.70" 1983

* Of the 30 days in June, 29 of them were 90°F or higher (19 days were 95°F or higher).

* Every day in July was 95°F or higher (27 days were 100°F or higher).

* Of the 31 days in August, 25 of them were 95°F or higher (14 days were 100°F or higher).

* The hottest day of the summer was August 3rd, with a high temperature of 113°F.

* The longest stretch of temperatures greater than or equal to 95°F lasted 42 days, from June 29th until August 9th.

* The longest stretch of temperatures greater than or equal to 100°F lasted 14 days, from July 26th until August 8th.

Fort Smith, AR:

Fort Smith, AR

Monthly Average Temperature Departure from 1981-2010 Normal
Rank Record
Monthly Average High Temperature Normal Monthly High Temperature Monthly Average Low Temperature Normal Monthly Low Temperature
June 2011 85.0°F +7.2°F #1 hottest 85.0°F 2011 96.3°F 88.1°F 73.7°F 67.5°F
July 2011 91.2°F +8.9°F #1 hottest 91.2°F 2011 104.1°F 93.0°F 78.4°F 71.6°F
August 2011 88.2°F +6.1°F #2 hottest 88.4°F 1936 100.4°F 93.4°F 76.0°F 70.8°F
Summer 2011 88.2°F +7.4°F #1 hottest 88.2°F 2011  100.3°F 91.5°F 76.1°F 70.0°F

 

Fort Smith, AR
 Rainfall  Departure from 1981-2010 Normal  Rank  Record
June 2011 0.44" -3.84"  #3 driest 0.38" 1914
July 2011 0.22" -3.08" #7 driest 0.07" 2001
August 2011 4.13" +1.54" #33 wettest Trace 2000
Summer 2011 4.79" -5.38" #11 driest  2.94" 1934

* Every day in June was 90°F or higher (23 days were 95°F or higher).

* Every day in July was 95°F or higher (30 days were 100°F or higher).

* Of the 31 days in August, 25 of them were 95°F or higher (13 days were 100°F or higher).

* The hottest day of the summer was August 3rd, with a high temperature of 115°F.

* The longest stretch of temperatures greater than or equal to 95°F lasted 42 days, from June 29th until August 9th.

* The longest stretch of temperatures greater than or equal to 100°F lasted 35 days, from July 5th until August 8th.

Oklahoma State Records:

* The state of Oklahoma had the 2nd hottest June, with an average temperature of 83.6°F.  The record is 84.6°F from 1953.

* The state of Oklahoma had the hottest July, with an average temperature of 89.3°F.  The old record was 88.1°F from 1954.

* The state of Oklahoma had the hottest August, with an average temperature of 87.9°F.  The old record was 87.2°F from 1936.

* The state of Oklahoma had the hottest summer (June - August) on record, with an average temperature of 86.9°F.  The old record was 85.2°F from 1934.

* The state of Oklahoma had the 4th driest June, with an average rainfall of 1.13 inches.  The record is 0.46 inches from 1933.

* The state of Oklahoma had the 4th driest July, with an average rainfall of 0.71 inches.  The record is 0.41 inches from 1980.

* The state of Oklahoma had the 43rd driest August, with an average rainfall of 2.31 inches.  The record is 0.14 inches from 2000.

* The state of Oklahoma had the 3rd driest summer (June - August) with an average rainfall of 4.15 inches.  The record is 2.79 inches from 1936.


Effects of the Drought

The extremely hot and dry conditions had dire consequences across all of the Southern Plains, including crop and livestock losses, water restrictions, brush fires, losses in recreation due to low lake levels, and numerous heat related illnesses and deaths. In Oklahoma, a majority of range and grazing pastures were classified as in "very poor" condition for much of the 2011 crop growing season.  The persistent heat and drought scorched cattle grazing fields and devastated hay and corn crop production.  Cattle farmers had to sell off their cattle herds when they were unable to keep them watered and fed due to high hay prices, and dried out watering holes.

devastated corn crop low farm pond

Devastated Corn Crop in NE Canadian County, OK - July 19, 2011

Photo Credit: Oklahoma Farm Report

Dried-up Farm Pond in Southern OK - July 2011

Photo Credit: Oklahoma Farm Report


Continued drought, paired with periods of extreme heat and gusty winds, created conditions favorable for a series of wildfires across Oklahoma.  Burn bands were ordered for counties across much of the state during June, July and August.  One large wildfire in early August destroyed over 20 homes, barns, and cars in southern Pawnee County, near Terlton.  The thick black smoke from the fire also closed the Cimarron Turnpike temporarily, backing up hundreds of cars.  In 2011, Oklahoma Forestry Services battled 1,745 fires, burning over 132,000 acres.

sapulpa fire tulsa fire

Wildfire near Sapulpa, OK - August 2, 2011

Photo Credit: AP-Tulsa World

Wildfire in Tulsa, OK - August 2, 2011

Photo Credit: AP-Tulsa World

With little rainfall during the summer or fall months, lake and river levels have dropped to near record levels.  Many boat ramps are still exposed, and docks grounded, making it difficult for boaters to venture out on the lakes.  Lakeside resorts and businesses have lost much of their summer revenue due to the heat and below normal water levels, along with the blue-green algae outbreak in July.  On a positive note, however, it enabled the clean-up of lake shores and boat ramp repairs which aren't possible unless water levels are low.

low Arkansas River in Tulsa exposed boat ramp

Arkansas River in Tulsa, OK - April 1, 2011

Photo Credit: Stephen Pingry - Tulsa World

Exposed Boat Ramp at Pine Creek Lake, OK - November 4, 2011

Photo Credit: U.S. Army Corps of Engineers

Many of the Oklahoma lakes, including Grand Lake, Keystone Lake, Fort Gibson Lake, Lake Tenkiller, Skiatook Lake, and Lake Eufaula were either closed or under an advisory or warning due to the development of a toxic blue-green algae.  The unusual heat and lower lake levels at many Oklahoma lakes promoted the development of the toxic algae during the months of June, July, and August.  Several people were hospitalized with respiratory problems, and several of the lakes were later closed.  The blue-green algae can affect the nervous system and liver, causing weakness, muscle tremors, and even death.  The algae can also contaminate marine life and any animals drinking from the affected water.

 algae bloom algae in Grand Lake

Blue-green Algae in Eufaula Gentry Creek area, OK - July 2011

Photo Credit: KOTV

Blue-green Algae at Grand Lake, OK - July 2011

Photo Credit: AP

The hot and dry weather also took its toll on the public.  Individuals with heat stroke or heat exhaustion were seen at local hospitals, fire departments, and police stations state-wide.  By the end of the summer, 20 people had died in Oklahoma due to the heat.  The heat also caused an extreme demand on electricity to run air conditioners.  Many residents lined up at locat cooling stations to get in out of the heat.  Based on NOAA's Residential Energy Demand Temperature Index, the contiguous U.S. temperature-related energy demand was 22.3 percent above average during summer 2011. This is the largest such value during the index’s period of record, which dates to 1895.  Temperatures got so hot, that several streets, and even highways, buckled as the concrete expanded.  Well below normal precipitation also caused water shortages across much of the state in July and August.  Residents were asked to restrict their water usage, limiting outside watering to certain hours of the day and certian days of the week.  These water shortages have persisted into the winter months in some counties, including Pawnee county, which is still asking residents to conserve water, and may have to purchase water from Stillwater if the drought continues into the summer months of 2012.

cooling station road buckled

Cooling Station inTulsa, OK - August 5, 2011

Photo Credit: KTUL

Road buckled on Cimarron Turnpike, OK - July 11, 2011

Photo Credit: KOTV


So, why was it so hot and dry?

Many factors go into such a significant drought that the Southern Plains experienced during 2011, and continues to experience in 2012.

First, the El Nino - Southern Oscillation (ENSO) was in the La Niña phase.  This means that the equatorial waters of the Pacific Ocean off the western coast of South America are cooler than normal.  This has an effect on the weather across the United States, shifting the jet stream further north across the northern half of the nation.  This shift in the jet stream, in turn, can lead to an enhanced chance for drier and warmer weather in the Southern Plains.

Second, a large area of high pressure developed across the southeastern portion of the country during the early part of June, and persisted for much of June, July, and into the first part of August.  The dome of high pressure would shift toward the west and east at times, however, never fully exiting the region.  This created the unusually hot and dry conditions that continued through much of the summer months.

These two weather situations, combined, created the unusually hot and dry conditions we experienced during the summer months.  By the time summer 2011 arrived, the Southern Plains were already experiencing drought conditions, especially Texas and western Oklahoma.  Once the summer heat began in June and the large area of high pressure developed over the southern portion of the nation, very little rain was able to move into the region.  The rain that did move into the area evaporated quickly due to the high heat and dry soil conditions, or was so minimal, it didn't help to improve the drought conditions.

La Nina impacts

July surface map

Schematic of La Niña effects on the U.S. Surface weather map from July 18, 2011 at 7am CDT

 


What can we expect for the winter, spring, and summer of 2012?

Once September 2011 arrived, the extreme heat finally broke, with temperatures slightly below average for the month.  November brought some much needed rain, with an average of 4.87 inches state-wide (ranking it the 9th wettest November).  Southeast Oklahoma received nearly 20 inches of rain during the month, creating flooding across portions of Le Flore and Pushmataha counties.  The cooler and wetter weather greatly improved the drought across Oklahoma, especially across the eastern half of the state.

A weak to moderate La Niña pattern is expected to continue in the Pacific Ocean through the remainder of the winter season, and into the early spring, before dissipating.  This pattern will tilt the odds in favor of warmer than average conditions across eastern Oklahoma and northwest Arkansas through the summer.  When it comes to precipitation however, there is no strong signal in eastern Oklahoma and northwest Arkansas to tilt the odds to wetter or drier.  So for now, there is an equal chance for above, near, and below normal rainfall across this area.  You can continue to monitor the latest drought information from the eastern Oklahoma and northwest Arkansas drought page.

 CPC 3-month temperature outlook  CPC 3-month precipitation outlook
 3-month Temperature Outlook  3-month Precipitation Outlook

 For current drought conditions see the links below:

 drought monitor for south  U.S. Seasonal Drought Outlook
Drought Monitor for the Southern Plains National Seasonal Drought Outlook

Updated: February 23, 2012


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