The Winter Winter Recap and Spring Outlook Jason Hansford Senior Forecaster National Weather Service Forecast Office Shreveport, LA

December Rainfall December Observed Rainfall Departure From Normal

2011 Total Precipitation City:2011 Total Precip. Departure from Normal Rank (Driest) 2010 Total Precip. Shreveport, LA33.07 in in.17 th in. Monroe, LA49.52 in in in. Texarkana, AR30.69 in in.11 th in. El Dorado, AR37.62 in in.15 th in. Tyler, TX24.97 in in.3 rd in. Longview, TX30.54 in in.9 th in. Lufkin, TX33.77 in in.21 st in.

December-March Rainfall Departure From Normal 90 Day Observed Rainfall

April Rainfall (Ending 4/16/12) Observed Rainfall Departure From Normal

Cumulative Winter Rainfall City:Dec. - Feb. Rainfall Departure from Normal % of Normal Shreveport, LA14.63 inches+0.91 inches107% Monroe, LA18.04 inches+3.11 inches121% Texarkana, AR11.27 inches-1.17 inches91% De Queen, AR8.60 inches-2.76 inches76% El Dorado, AR14.58 inches+0.31 inches102% Tyler, TX11.88 inches+0.77 inches107% Longview, TX13.31 inches+1.46 inches112% Lufkin, TX15.25 inches+2.76 inches122%

March Flooding Significant rainfall (widespread 4-8 inches, isolated amounts > inches) area wide. Drought has been eliminated across most areas. Significant rainfall (widespread 4-8 inches, isolated amounts > inches) area wide. Drought has been eliminated across most areas. March Month to Date Rainfall: Departure from Normal:

The March Flood Contributor

March Monthly Rainfall City:March Rainfall:Departure from Normal: Rank for Wettest March on Record: Shreveport, LA7.94 in in.10 th Monroe, LA10.67 in in.2 nd Texarkana, AR5.52 in in El Dorado, AR8.77 in in.9 th De Queen, AR5.27 in in Tyler, TX6.38 in in Longview, TX4.77 in in Lufkin, TX8.67 in in.2 nd

Hydrological Drought Impacts Cane River in Natchitoches, LA Measured near 2 ft. on 10/11/11 (Photo courtesy of Wiley Butler) Cane River in Natchitoches, LA Measured near 2 ft. on 10/11/11 (Photo courtesy of Wiley Butler) Cane River in Natchitoches, LA Taken 3/21/12 around 10 am (Photo courtesy of Wiley Butler) Cane River in Natchitoches, LA Taken 3/21/12 around 10 am (Photo courtesy of Wiley Butler)

Hydrological Drought Impacts Cane River in Natchitoches, LA June 17 th, 2011 (Photo courtesy of Wiley Butler) Cane River in Natchitoches, LA June 17 th, 2011 (Photo courtesy of Wiley Butler) Cane River in Natchitoches, LA March 21 st, 2012 (Photo courtesy of Wiley Butler) Cane River in Natchitoches, LA March 21 st, 2012 (Photo courtesy of Wiley Butler)

Calculated Soil Moisture (Ending March 24, 2012) Soil Moisture has INCREASED to mm (20-24 in.) deep! Soil Moisture has returned to near/slightly above normal!

Calculated Soil Moisture (Ending April 13, 2012)

Soil Moisture Comparison

Drought Severity Indices Palmer Drought Severity Index: Is most effective in determining long term drought by using temperature and precipitation to calculate dryness. It is also standardized to the local climate. a)Measured on a scale of -4 to 4, with negative values indicating drought, and positive values indicating moisture surplus. Crop Moisture Index (CMI): Is a short term drought index, based on precipitation, dryness, and wetness affecting agriculture. It changes more rapidly from week to week than the Palmer Index. a)Uses the same scale as the Palmer Index. Palmer Drought Severity Index: Is most effective in determining long term drought by using temperature and precipitation to calculate dryness. It is also standardized to the local climate. a)Measured on a scale of -4 to 4, with negative values indicating drought, and positive values indicating moisture surplus. Crop Moisture Index (CMI): Is a short term drought index, based on precipitation, dryness, and wetness affecting agriculture. It changes more rapidly from week to week than the Palmer Index. a)Uses the same scale as the Palmer Index.

Palmer/Crop Moisture Index

U.S. Drought Monitor (April 17 th, 2012)

U.S. Drought Monitor (October 25 th, 2011)

2011 Avg. Monthly Temperature City:2011 Avg. Monthly Temp. Departure from Normal: Rank: Shreveport, LA68.2°+2.5°T4 th (with 1927 and 2006) Monroe, LA68.2°+2.4°1 st Texarkana, AR66.0°+2.1°T5 th (with 2005) El Dorado, AR64.4°+0.9°T20 th (with 1945 and 2004) Tyler, TX69.1°+3.7°2 nd (behind 1921 at 69.6°) Longview, TX68.5°+3.1°T1 st (with 1911) Lufkin, TX68.9°+2.1°2 nd (behind 1998 at 69.1°)

CONUS Temperature Departure from Normal

Winter Temperature Comparison (“The Winter That Wasn’t”) City:Dec. – Feb. Avg. Temperature: Departure from Normal: Warmest Winters Rank: Shreveport, LA52.6°+4.0°14 th Monroe, LA51.9°+3.6°4 th Texarkana, AR49.0°+3.2°17 th El Dorado, AR47.2°+1.5°31 st Tyler, TX51.0°+2.7°8 th * Longview, TX51.3°+3.1°8 th Lufkin, TX53.6°+3.0°T10 th ** * Tied for 8 th warmest winter on record with Sporadic records since ** Tied for 10 th warmest winter on record with Records since 1906.

Month by Month Temperature Comparison for Shreveport, LA (Nov – April 15 th, 2012)

March Avg. Temperature City:March Avg. Temperature: Departure from Normal: Rank for Warmest March on Record: Shreveport, LA67.3°+9.4°1 st Monroe, LA68.0°+10.0°1 st Texarkana, AR64.8°+8.9°3 rd El Dorado, AR63.0°+7.2°3 rd De Queen, AR61.2°+8.0°2 nd Tyler, TX65.6°+8.7°3 rd Longview, TX65.9°+8.3°3 rd Lufkin, TX67.2°+7.6°2 nd

Arctic Oscillation Refers to the atmospheric circulation pattern in the northern middle and high latitudes in the Arctic. These can generate strong shifts in the climate pattern than can overwhelm or amplify the typical La Niña impacts. 1)Exhibits a negative phase when higher pressures develop over the Polar region, and low pressures develop in the mid- latitudes (near 45°N). This results in frigid air plunging south into North America east of the Rockies. 2)Exhibits a positive phase when lower pressures develop over the Polar region, and higher pressures develop in the mid- latitudes. This will keep the frigid air locked up in the Arctic region, but also drives ocean storms farther north. Thus, wetter weather is usually associated throughout Alaska, Scotland, and Scandinavia. Refers to the atmospheric circulation pattern in the northern middle and high latitudes in the Arctic. These can generate strong shifts in the climate pattern than can overwhelm or amplify the typical La Niña impacts. 1)Exhibits a negative phase when higher pressures develop over the Polar region, and low pressures develop in the mid- latitudes (near 45°N). This results in frigid air plunging south into North America east of the Rockies. 2)Exhibits a positive phase when lower pressures develop over the Polar region, and higher pressures develop in the mid- latitudes. This will keep the frigid air locked up in the Arctic region, but also drives ocean storms farther north. Thus, wetter weather is usually associated throughout Alaska, Scotland, and Scandinavia.

Arctic Oscillation (Nov. – Mar Current) Limitations to Forecasting: Strong AO episodes typically last only a few weeks, and are difficult to predict more than a week or two in advance. Limitations to Forecasting: Strong AO episodes typically last only a few weeks, and are difficult to predict more than a week or two in advance.

North Atlantic Oscillation Fluctuations in the difference of sea-level pressure between the Icelandic Low and the Azores high. Fluctuations in the difference of sea-level pressure between the Icelandic Low and the Azores high. + NAO prevents cold air from plunging southward over eastern North America. + NAO prevents cold air from plunging southward over eastern North America. Shows multi-decadal signal. Shows multi-decadal signal. Has an effect on Hurricanes in the Atlantic. (During +NAO events, the Bermuda High is weaker, allowing for a more W-E flow across the Atlantic. SST’s in the Atlantic are also unusually cold following +NAO winters.) Has an effect on Hurricanes in the Atlantic. (During +NAO events, the Bermuda High is weaker, allowing for a more W-E flow across the Atlantic. SST’s in the Atlantic are also unusually cold following +NAO winters.)

Historical NAO Index Strong positive anomalies this past winter. Strong negative anomalies last winter.

Monthly Observed Arctic and North Atlantic Oscillation Indices

SST’s in the Equatorial Pacific Niño 3.4 Region: 5°N - 5°S and 170° - 120°W [] []

Long Term SST Anomalies

La Nina is Ending! So, What’s Next?!

Probabilistic ENSO Forecast

Spring Outlook TemperaturePrecipitation

20 Month Rainfall and Departures (Mar. ’10-Apr. 11 ‘12) City:Total Precipitation: Departure from Normal: % of Normal: Shreveport, LA % Monroe, LA % Natchitoches, LA % Texarkana, AR % El Dorado, AR % Hope, AR % Dequeen, AR % Idabel, OK % Mt. Pleasant, TX % Tyler, TX % Longview, TX % Lufkin, TX %

Long Term Drought Outlook

The End Any Questions???