TORNADO OUTBREAK IN OKLAHOMA, ARKANSAS, AND IOWA Round One: April 26-27, 2014 Walter Hays, Global Alliance for Disaster Reduction, Vienna, Virginia, USA

The most destructive tornado outbreak of 2014 killed at least 18 people in three states and hammered the suburbs of Little Rock, Arkansas over a 200-mile-long path.

THE FORECAST: APRIL 14

ACTUAL: APRIL 26-27

In all, at least 31 tornadoes were recorded. They formed late in the day, and were especially destructive in Arkansas because they struck as night fell.

Some of the tornadoes were rated as EF-3, which have wind fields of at least 246 kph (136 mph).

VILONIA, ARKANSAS (ALSO HIT BY TORNADOES IN 2011)

IMPACTS Faulkner County, Ark., particularly the suburbs of Mayflower and Vilonia, was the hardest hit on Sunday, with as many as 18 people dead, including two children At least 150 homes destroyed. Two highways closed; 20,000 power outages

“ROUND TWO” MONDAY, APRIL 28 Millions of people braced for more severe weather as at least three tornadoes struck Mississippi on Monday afternoon.

TUEPLO, MISSISSIPPI: APRIL 28

INITIAL IMPACT REPORTS A tornado hit Tupelo and tracked northward, causing "significant property damage, but no deaths" Tueplo Mayor Jason Shelton said.

BACKGROUND SEVERE WINDSTORMS-- TORNADOES

UNDERSTANDING AND PREPARING FOR TORNADOES A PRIMER OF KNOWLEDGE THAT CAN MULTIPLY AND SPILL OVER FOR THE BENEFIT OF MILLIONS

THE PHYSICS OF SEVERE WINDSTORMS SEVERE WINDSTORMS: TORNADOES

COMMUNITYCOMMUNITY DATA BASES AND INFORMATION SEVERE WINDSTORM HAZARDS INVENTORY VULNERABILITY LOCATION RISK ASSESSMENT RISK ACCEPTABLE RISK UNACCEPTABLE RISK SEVERE WINDSTORM RISK REDUCTION PREVENTION/MITIGATION PREPAREDNESS EMERGENCY RESPONSE RECOVERY and RECONSTRUCTION EDUCATIONAL SURGES POLICY OPTIONS Wind profile Storm Hazards: -Wind pressure -Surge -Rain -Flood -Waves -Salt water -Missiles -TornadoesOceanOcean Gradient Wind

WIND AND WATER PENETRATE BUILDING ENVELOPE SEVERE WINDSTORMS SEVERE WINDSTORMS UPLIFT OF ROOF SYSTEM FLYING DEBRIS PENETRATES WINDOWS HEAVY PRECIPITATION IRREGULARITIES IN ELEVATION AND PLAN POOR WORKMANSHIP IGNORING NON-STRUCTURAL ELEMENTS CAUSES OF RISK CASE HISTORIES

BASIC PRINCIPLES OF PHYSICS UNDERPINNING WINDSTORMS HEAT AND HEAT FLOW PRESSURE AND PRESSURE FLOW GRAVITY FIELD KINETIC ENERGY POTENTIAL ENERGY

SEVERE WINDSTORMS TORNADOES OCCUR OVER LAND AS THE RESULT OF COLLISIONS OF COLD AND WARM AIR MASSES

TORNADOE SEASON The peak tornado season is late winter through midsummer,…. But tornadoes can happen any time of the year when the atmospheric conditions are right.

TORNADO ALLEY ALTHOUGH TORNADOES HAVE OCCURRED IN EVERY STATE, THEY OCCUR MOST FREQUENTLY IN “TORNADO ALLEY,” WHICH INCLUDES PARTS OF: TEXAS, OKLAHOMA, ARKANSAS, TENNESSEE, NEBRASKA, KANSAS, MISSOURI, ILLINOIS, AND IOWA.

MAP OF TORNADO ALLEY

THE PHYSICS OF TORNADOES TORNADOES ARE CAUSED BY THE COLLISION OF DESCENDING COLD AIR MASSESS COMING FROM THE NORTH AND ASCENDING WARM AIR MASSES COMING FROM THE SOUTH.

THE PHYSICS OF TORNADOES THE COLLISION CREATES A FUNNEL OF HIGH-VELOCITY WIND THAT IS VERY DESTRUCTIVE AS IT “TOUCHES DOWN” ONE OR MORE TIMES ALONG A LONG, NARROW (TYPICALLY M) PATH.

PHYSICS OF A TORNADO

HAZARDS OF A TORNADO (AKA POTENTIAL DISASTER AGENTS) WIND: SPEEDS CAN REACH 500 KM/HR (300 MI/HR) THUNDER, LIGHTNING, AND HEAVY PRECIPITATION E EXTREME HAIL CAN BE VERY DAMAGING

HISTORIC OCCURRENCES

THIRTY TO FORTY TORNADOES STRIKE FIVE SOUTHERN STATES Mississippi, Alabama, Arkansas, Kentucky, and Tennessee impacted 54 dead FEBRUARY 5, 2008

LOCATION MAP

TORNADOE SEASON AFFECTED BY LA NINA This tornado outbreak could be a consequence of La Nina, the cooling of the Pacific Ocean, which can cause changes in weather patterns around they world.

WARNING The people had ample warning to get out of harm’s way and take cover, … In spite of the fact that some of the warning sirens did not work.

A TORNADO TOUCHES DOWN NEAR ATKINS, ARKANSAS

DEVASTATION NEAR ATKINS, ARKANSAS

COLLAPSE OF WAREHOUSE IN SOUTH HAVEN, MS

COLLAPSE OF WALL IN SHOPPING MALL: MEMPHIS, TN

A FIRE BROKE OUT IN A NATURAL GAS PUMPING STATION: HARTSVILLE, TN

SEVERE THUNDERSTORM SYSTEM SPAWNS TORNADOES IN TEXAS: APRIL 24, 2008

A SUPERCELL

THE FUNNEL

IMPACTS IN WEST AND NORTH TEXAS WORST DAMAGE NEAR FT WORTH, TX WITH LOSSES ESTIMATED AT $35 MILLION WIND SPEED REACHED 116 KM/HR (70 MI HR)

IMPACTS IN WEST AND NORTH TEXAS HEAVY RAIN FALL CAUSED POWER OUTAGES AND MINOR FLOODING BASEBALL-SIZED HAIL

WIND DAMAGE

TORNADOES STRIKE IOWA AND MINNESOTA Continuation of deadliest tornado season in a decade Accompanied by large hail May 25, 2008

HUGO, MINNESOTA: DEBRIS MARKS STORM'S PATH

PARKERSBURG, IOWA: DAMAGE

PARKERSBURG, IOWA: LOOKING FOR SURVIVORS

LESSONS LEARNED FROM TORNADOES RECOVERY USUALLY TAKES LONGER AND COSTS MORE THAN EXPECTED.

LESSONS LEARNED FROM TORNADOES EVACUATION IS NOT TO THE STREET; IT IS TO THE BASEMENT OR THE “SAFE ROOM” BECAUSE THE WARNING IS EITHER VERY SHORT OR NON-EXISTANT.

LESSONS LEARNED FROM TORNADOES TIMELY COMMUN- ICATION OF CRITICAL INFORM- ATION IN THE FORM OF WATCHES AND WARNINGS IS ESSENTIAL FOR SAFETY.

LESSONS LEARNED FROM ALL TORNADOES HIGH VELOCITY WIND LIFTS THE ROOFS OFF OF BUILDINGS AND IS A KILLER IN TORNADOES.

LESSONS LEARNED FROM ALL SEVERE WINDSTORMS HIGH VELOCITY WIND AND PRESSURE CHANGES CAUSE BUILDINGS WITH INADEQUATE ENGINEERING DESIGN TO COLLAPSE.

RISK ASSESSMENT INTEGRATES RESEARCH AND SCIENTIFIC KNOWLEDGE GAINED FROM “DISASTER LABORATORIES,” WITH EMERGING TECHNOLOGIES INTO POLICY TO BE IMPLEMENTED IN THE COMMUNITY’S POLITICAL PROCESS.

PUBLIC POLICIES INTEGRATE TECHNICAL AND POLITICAL SOLUTIONS FOR THE LONG-TERM BENEFIT OF THE PEOPLE.