weather and climate across south-central texas

WEATHER 101

Weather & Climate Across South-Central TexasJason RunyenSenior ForecasterNational Weather ServiceAustin-San Antonio TX

Flash Flood Alley

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Weather Defined

The state of the atmosphere at some place and time, described in terms of such variables such as:TemperatureCloudinessPrecipitationWind speed and direction

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Climate DefinedWeather conditions at some locality averaged over a specified time period.Departures/Variability from long-term averages Extremes in weather

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Lets Talk AboutWeather First

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What Causes The Weather?The sun heats Earth unequallyOnly half the planet receives sun at one timeAmount of radiation varies from place to placeEarth tilts as it revolves around the sun

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SeasonsEqual Day/NightEqual Day/NightDay>NightNight>Day14+ hours 14+ hours

Effects of Clouds on Temperaturein daytimeCloudy skies = cooler temperatures

Clear skies = warmer temperatures

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Effects of Clouds on Temperatureat night

Clear skies = cooler temperatures

Cloudy skies = warmer temperatures

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Types of Air MassesAir massWinterSummerContinental ArcticBitter cold and dryn/aContinental PolarVery cold and dryCool and dryContinental TropicalWarm and dryHot and dryMaritime PolarMild and humidMild and humidMaritime TropicalWarm and humidWarm and humid

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Cold Front

Cooler, denser air is advancing to replace warm air

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Warm Front

Transition between warm air and colder air

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Other Boundaries

Sea breeze and land breeze

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Clouds cover roughly 50% of Earth at a Given Time

Clouds

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Clouds Tell Us Different Things about the State of the Atmosphere

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1. Surface Heating - EvaporationWays to Make a Cloud

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2. Hills & Mountains Orographic liftWays to Make a Cloud

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3. Air Pressure

LWays to Make a Cloud

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4. Cold or Warm FrontWays to Make a Cloud

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Tools to Monitor Weather: Satellite

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Christmas 2004 Snow

January 1985 SnowTools to Monitor Weather: Satellite

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Tools to Monitor Weather: NWS Radar

Smoke From Bastrop, TX Wildfire

Smoke PlumesTools to Monitor Weather: NWS Radar

Bracken Cave Bats

Biological

Tools to Monitor Weather: NWS Radar

Instability

L

Moisture

Lift

WindShear

Severe StormsMoistureInstabilityLiftWind ShearHow Ordinary Thunderstorms Become SevereIngredients for a Severe ThunderstormIngredients for Severe Storms Often Come Together Across Texas During Spring

Hot and Dry Across Texas During Summer with High Pressure Aloft

Occasionally Weak Areas of Low Pressure Aloft Can Bring Storms during June and July

Risk of Tropical Cyclones from Gulf and Caribbean During Summer

Risk of Tropical Cyclones from Long Track Atlantic Storm During September

Pacific and Gulf Moisture Can Interact with Fronts to Bring Heavy Rainfall Sep-Oct

Sub-Tropical Jet Stream

Large Dips in Jet Stream Can Send Arctic Airmass South into Texas During Winter. Moisture Overrunning Can Bring Wintry Mix

Moisture

Wintry MixCOLD

Variability of Temps and Precip During Winter & Spring Dependent on Natural Climate Cycles Such as ENSO

1,000+ Tornadoes

10,000+ Severe StormsWeather Hazards in the U.S.

Winter StormsDrought

2,500Floods

7 Hurricanes

Flash Flood Alley#1 Storm-Related KillerDont drive through low water crossings!

Flash FloodingTerrain, Heavy Rainfall, and Population Centers Dont Mix

A perfect storm with a mix of heavy rain events, little to no soil, and terrain. Throw in some urban areas with asphalt and concrete and you have a very unique location in the United States.

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118 Deaths in South Central Texas since 1996Flash Flood Fatalities

There are 225 Flood/flash flood fatalities in the state 1996-2014. Our cwa has 118. rest of state has 107. so our CWA has more than 50% of the states flood deaths.Bexar county has the most of any county in the state.36

Record May RainfallMemorial Day 2015 Flooding

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How Quickly a Flash Flood Can HappenBlanco River at Wimberley

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Blanco River Flood 2015

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Over 200 homes affected in the Bexar county areawith nearly 40 receiving major damage or destroyed. Most of the Destroyed homes where in SE San Antonio, away from the heavy rain core. 40

USGS River Gauge, Inside the 410 Loop

2.58 inches in 15 minutes 6.13 inches in 1 hour 8.59 inches in 1.5 hours 9.46 inches in 2 hours13.70 inches in 4 hours15.31 inches in 5 hours17.00 inches in 24 hours

Result of cell mergers near this area. 41

14 of Rain

Onion creek in South Austin peaked at 930 AM at 40.15 ft.new record height. Estimated flow was at 135,000 cfs. 825 homes were impacted by the flood.with nearly 500 of them being heavily damaged or destroyed. 7 Fatalities reported in South Central Texas. Core of the rain fell across two main basins, the Onion Creek watershed which has Onion creek starting in Hays County and then it goes into southern Travis County/Austin eventually dumps into the Colorado River. Rain around Wimberley dumps in the Blanco River basin which flows to the north side of San Marcos and crosses I-35 and merges with the San Marcos River.42

About a 12 hour loop from the evening of 10-30 through the morning of 10-31.43

They Wont Save You

Dont Rely on Your Big Vehicles

It typically will take 18-24 of swift moving water to push most vehicles off the road. 1 foot of water will displace about 3000 lbs. The faster the water is moving, the less water it takes. People take more chances with their SUVs and PickUp trucksthey think they can make it through the water.

Pix on the top left is of a school board member coming back from a meeting near Hunt Texas in Kerr County in April 2010. Long term residentBottom left was lady that died in Austin during the 2010 TS Hermine rains, died near Bull Creek and FM2222, drove around an ongoing rescue. Long term resident and business owner.44

5537 Large Hail ReportsLarge Hail Reports in 2014

11986 Straight-Line Wind ReportsSevere Straight Line Wind Reports in 2014

1057 Tornado ReportsTornado Reports in 2014

These are preliminary reports from LSRs. Not official. We had 3 official tornadoes in 20142 up in Burnet County, 1 in Bastrop County.47

All Tornadoes 1950-2013

We have had 30 tornadoes in our EWX area since 2008. 3 EF2s, 4 EF1s, 23 EF0s 48

81% of South-Central Texas TornadoesCauses 7% of all deathsLife span 1-2 minutesPath length less than 1 mileWind speeds up to 110 mphMany are difficult to detect by radarDifficult to get spotter confirmationMany go unreportedWeak TornadoesEF0-EF1

49You wont always see a funnel all the way to the ground. Look for debris at ground level to confirm its a tornado.

18% of South-Central Texas TornadoesCauses 42% of all deathsLife Span 15-20 minutesPath length up to 15 milesPath width up to 500 yardsWind speeds up to 165 mphEasily identified by NWS Doppler RadarGood spotter confirmationMost are reported

Strong TornadoesEF2-EF3

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Violent TornadoesEF4-EF5

Less than 1% of South-Central Texas TornadoesCauses 51% of all deathsLife Span many minutes to hoursPath length up to 20-50 milesPath width up to to 1 MileWind speeds over 200 mphVery easily identified by NWS Doppler Radar TDS Signatures

Jarrell, TX Tornado - 1997

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Now Lets TalkAbout Climate

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What is Average? - PrecipitationYear to Year Variability and Trends in Annual Precip San Antonio & Kerrville

What is Average? - PrecipitationVariability in Annual Precip San Antonio

1886-2014: Mean Precip 28.76Standard Deviation 9.071985-2014:Mean Precip 32.44Standard Deviation 10.53

Comparing Variability SeattleAnnual AverageStandard Deviation (Variability)Seattle 37.85Seattle 6.93San Antonio 32.44San Antonio 10.53

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What is Average? - TemperatureYear to Year Variability and Trends in Annual Temp San Antonio & Kerrville

Temperature TrendsTexas

Rainfall Variability During Wet Season

May 2011May 2015

Percent of Normal

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Drought2011 vs 2015

Droughts Effect on Temperature 2011 vs 2015

Droughts Effect on Temperature 2011 vs 2015

Drought Interrupted by Periods of Flood

Remember this from grade school!The Vicious Drought Cycle

Hydrologic Cycle

Lakes dry upGrass/fields get brownLess humidityLess RainLakes get lowerGrass/fields brownEven less humidityEven less RainWhat happens when it gets dry?





Atlantic Multi-Decadal Oscillation (ADO)Pacific Decadal Oscillation (PDO)El Nio Southern Oscillation (ENSO)Madden Julian Oscillation (MJO)North Atlantic Oscillation (NAO)Arctic Oscillation (AO)Pacific-North American Pattern (PNA)1-2 Weeks

30-60 Days

6-18 Months

Decades

Naturally Occurring Oscillations

Its a climate pattern that occurs across the tropical Pacific Ocean on average every two to seven years.What is El Nio Southern Oscillation? (ENSO)

Changes in ocean temperatures in the tropical Pacific is one of the most noticeable effects of ENSO

ENSOLa Nina Mean SST Anomalies

ENSOEl Nino Mean SST Anomalies

ENSOOscillation of Mean SST AnomaliesLa Nina Jan 1997El Nino Nov 1997

History of ENSO Since 1982El NinoLa Nina

ENSO ImpactsWinter Precipitation AnomaliesEl NinoLa Nina

ENSO ImpactsPrecipitation Impacts are NOT Identical, Even During Strong El NinosStrong El Nino 1982-83Strong El Nino 1965-66

ENSO ImpactsWinter Temperature AnomaliesEl NinoLa Nina

ENSO ImpactsEl Nino Winter vs Summer Precipitation AnomaliesEl Nino WinterEl Nino Summer

ENSO ImpactsWestern Gulf of Mexico HurricanesEl NinoLa Nina

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South-Central Texas Winter Severe WeatherENSO Impacts

ENSO ImpactsSouth-Central Texas Spring Severe Weather

ENSO ImpactsMeasurable Snow Years (1950-2015) San Antonio & AustinSAT - 16 Seasons AUS 21 Seasons

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Current SST Anomalies

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Current T-Depth AnomaliesDate LineOcean SurfaceOcean Surface

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El NioLa NiaENSO ForecastNeutral

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ENSO Probability Forecast

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TemperaturePrecipitationOutlooksFall 2015

TemperaturePrecipitationOutlooksWinter 2015-2016

TemperaturePrecipitationOutlooksSpring 2016

TemperaturePrecipitationOutlooksSummer 2016

Drought OutlooksFall 2016

El NioSouthernOscillation

MJO

NorthAtlanticOscillation

ArcticOscillation

PacificNorth AmericanPatternOur Climate Variability is driven by interaction of these Oscillations (Operating on Different Time Scales)

Drought

Flood

TornadoesIs Weather Getting Worse?

Is Reporting Getting Better?

Hundreds of chasers hit the road every day in the Spring and early Summer

Population Growth Are More People Living in Hazardous Areas?

Hundreds of chasers hit the road every day in the Spring and early SummerClimate Change


U.S. Billion Dollar Weather Disasters Trends (1980-2013)


U.S. Billion Dollar Weather Disasters Texas Leads Country (1980-2013)


Weather Cycles and Climate Change Effects on Ecology

Water Resources in Volatile Precipitation and Increasing Population Regions

Lake TravisEdwards Aquifer

Medina Lake

Jason [email protected] Austin/San Antonio2090 Airport RoadNew Braunfels, TX 78130830-606-3617 (public line) weather.gov/sanantonio

[email protected]?

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CoCoRaHS Community Collaborative Rain,Hail & Snow Network

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Local View - Google Maps

CoCoRaHS Community Collaborative Rain,Hail & Snow Network

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VolatilityTrend in Annual Precip Standard Deviation San Antonio

weather and climate across south-central texas

Environment