Weather Outlook for Spring and Summer in Central TX Aaron Treadway Meteorologist National Weather Service Austin/San Antonio
Outline A Look Back At 2014 Spring 2015 So Far El Niño Update Climate Prediction Center Outlooks 2015 Atlantic Hurricane Season
Austin Mabry & Bergstrom Bergstrom went 41 days without rain (7/25-9/3) 7 th longest period since 1942 (record: 64 days in 1993) Camp Mabry was only climate site that had above normal rain due to heavy rain event night of 7/17-7/18 (over 5 ) Over half of our rainfall in 2014 at both Camp Mabry and Bergstrom occurred in five events lasting 3 days or less! Austin Mabry: 1. 5.36 (7/16-7/18) 2. 4.14 (9/17-9/19) 3. 3.67 (11/20-11/22) 4. 3.53 (5/12-5/14) 5. 2.11 (11/4-11/6) 18.81 of 35.53 (52.9%) Austin Bergstrom: 1. 4.34 (5/12-5/14) 2. 3.72 (11/20-11/22) 3. 3.05 (5/27-5/28) 4. 2.85 (11/4-11/6) 5. 2.05 (9/17-9/19) 15.99 of 29.47 (54.3%)
Location Average Temp Normals Difference Austin Bergstrom 66.9 67.2-0.3 Austin Mabry 69.0 69.3-0.3 San Antonio 70.4 69.4 +1.0 Del Rio 70.9 70.5 +0.4 Location Average Max Temp Normal Max Temp Difference Austin Bergstrom 79.2 79.7-0.5 Austin Mabry 79.2 79.7-0.1 San Antonio 81.1 80.2 +0.9 Del Rio 82.1 81.6 +0.5 Location Average Min Temp Normal Min Temp Difference Austin Bergstrom 54.7 54.8-0.1 Austin Mabry 58.3 58.9-0.6 San Antonio 59.7 58.6 +1.1 Del Rio 59.8 59.2 +0.6
2014 36 th Warmest 75 th Coldest 2014 55 th Warmest 6 th Coldest
2014 Drought Monitor
Flash Flooding
2015 Climographs
2015 Precipitation So Far
Current Drought Monitor
April 12 th April 19th
Why may help be on the way? Warmer than normal sea surface temps (SSTs) in Pacific El Niño Conditions Latest Weekly SST Departures: 0.9 o C 1.3 o C 1.3 o C 0.8 o C La Niña Conditions
Oceanic Niño Index (ONI) ONI is based on SST departures from average in the Niñ0 3.4 region. 3 Month running-mean SST departure Definitions For El Niño: Positive ONI greater than or equal to +0.5ºC For La Niña: Negative ONI less than or equal to -0.5ºC 0.9 o C
ONI Evolution Since 1950 El Niño Neutral La Niña
El Niño Conditions Present! Approx. a 70% Chance that El Nino Conditions will Continue through summer 2015, and a greater than 60% chance it will last through autumn. El Niño Conditions Normal ( Neutral ) Conditions
El Niño Winter Teleconnections El Niňo typically causes subtropical jet to be active over southern U.S. and polar jet to be displaced to the north Subtropical jet Teleconnections are statistical linkages between changes occurring in widely separated regions
El Niño Winter Teleconnections El Niňo typically causes South Central Texas to be wetter and cooler than normal more than half of the time! 10-50% wetter than normal Trend Holds ~50% of the time Subtropical jet 1-2 o C cooler than normal Trend holds ~75% of the time
El Niño Conditions Continue!
El Niño 3.4 SST Model Outlook The majority of the models indicate Niño 3.4 SST anomalies will remain greater than or equal to +0.5C through the end of 2015. Figure provided by the International Research Institute (IRI) for Climate and Society (updated 14 April 2015).
El Niño Conditions Continue! The NCEP CFS.v2 ensemble mean (black dashed line) predicts El Niño through NDJ 2015-16.
6-10 Day Outlook
8-14 Day Outlook
May 2015
May / June / July Outlook
April Drought Outlook
April 16 th July 31 st Drought Outlook
2014 Hurricane Outlook AY 8-13 3-6 1-2 Actual 8 6 2
Normal and Record Activity Named Hurricanes Major Average (1981-2010) 12.1 6.4 2.7 Record High 28 (2005) 15 (2005) 7 (2005) Record Low 4 (1983*) 2 (2013*) 0 (2013*) *Last Year this Occurred
Tropical Storm Risk December Forecast ACE Major Hurricanes Hurricanes 79 (± 58) 2 (± 2) 6 (±3) 13(±4) April Forecast 56 2 5 11 Tropical Storms Two Professors in the Department of Science and Climate Physics at University College London, UK ACE Accumulated Cyclone Energy wind energy index. Reasons for Below Normal Season: Suppression of trade winds over the Caribbean and North Atlantic ENSO Neutral Conditions (not the current ENSO forecast) They note high uncertainty in their trade winds and SST forecasts
Colorado State University Major Hurricanes Hurricanes April Forecast 1 3 7 Tropical Storms Philip J. Klotzbach and William M. Gray One of the least active seasons since the middle of the 20 th Century Reasons For Forecast: Moderate Strength El Niῆo Negative Atlantic Multidecadal Oscillation (AMO) Positive North Atlantic Oscillation (NAO) Strong Atlantic Subtropical High & Strengthened Trade Winds
NAO Hurricane Teleconnections Iceland Azores NAO Positive Phase Subtropical high shifted to north and east (hurricanes recurve farther east) More East Coast landfalls (although most out to sea) NAO Negative Phase Subtropical high shifted to south and west (hurricanes blocked from recurving to the north) More Gulf Coast landfalls
El Niῆo Hurricane Teleconnections A Decreased Number of Storms in the Atlantic Basin Storms affected by atmospheric circulation, largely through the vertical wind shear profile. Increased vertical wind shear due to increases in westerly winds aloft. http://www.aoml.noaa.gov/hrd/landsea/lanina/
El Niῆo Hurricane Teleconnections
ENSO Hurricane Influence El Niño vs La Niña
North Carolina State University Major Hurricanes Hurricanes April Forecast 1 3 6 Named Storms Dr. Lian Xie, Professor of Marine, Earth and Atmospheric Sciences Significantly less active than the overall averages from 1950 to present Evaluates more than 100 years of historical data on Atlantic Ocean hurricane positions and intensity, as well as other variables including weather patterns and sea-surface temperatures, to predict how many storms will form in each ocean basin. Reminder that it only takes one landfalling storm to create loss of life and property see Hurricane Andrew (quiet 1992 Hurricane Season)
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