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May-June 2013

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U.S. Weather Highlights 2012: Heat, Drought, and Sandy

Heat, drought, and “Superstorm” Sandy headlined 2012. The warmest year on record featured one of the most extreme summer heat waves, the warmest spring in over a century, the most extensive drought in more than half a century, and the second most expensive cyclone of all time.

Almost the Year Without a Winter

The Lower-48 notched its fourth mildest and one of its least snowy winters in the past century, as the polar wind patterns kept cold air bottled up to the north.

Getting the year off to an abnormally mild start, January temperatures averaged 8°F or more above normal in the northern Plains, and every region in the contiguous United States measured above-normal temperatures. February continued the mild trend.

In stark contrast, Alaska noted its coldest January on record, averaging 14°F below the 1971–2000 average. Fairbanks recorded a memorable January average of −26.9°F (19 degrees below normal!). Minima dipped to −48°F on both January 14 and 15.

Despite the overall mild trend, the Lower-48 did experience several tastes of winter weather. An historical snow and ice storm struck the Northwest on January 18–20, leaving near-record snowfall in Western Washington (seven inches at Seattle, its sixth highest total of record), and temperatures dipped below freezing in the Southeast as far south as Daytona Beach on January 4–5. Up to three feet of snow buried the Colorado mountains west of Denver and Boulder in early February. Denver's 15.9 inches on February 2–4 represented its greatest February three-day snowfall on record.

An Early Start to the Severe Thunderstorm Season

The severe weather season got off to an early start but, thankfully, rapidly tapered off during the spring.

On January 22–23, 25 tornadoes ripped across the South, resulting in two deaths in Alabama and property damage exceeding $175 million. The Birmingham area sustained major damage early on January 23, as tornadoes hit the western and northern parts of the city. An EF-3 struck Clay, Alabama, destroying some 374 homes and businesses and injuring at least 100 people.

In one week in late February and early March, three major storm systems crossed the nation, with the second and third resulting in deadly tornado outbreaks. The February 28–29 storm launched a blizzard in the upper Midwest and spread tornadoes from Kansas to Indiana. The severe weather was blamed for 15 deaths and over $500 million in damages. One twister devastated much of Branson, Missouri.

Another frontal system triggered an historical outbreak on March 2, with twister reports extending from Illinois to North Carolina. Dozens of tornadoes swept across 12 states, killing 13 people in Southern Indiana and 22 in Kentucky. The storms nearly wiped out several towns in Southern Indiana, including Henryville and Marysville. West Liberty, Kentucky, also sustained catastrophic damage. The final toll stood at 40 dead and more than $4 billion in damage.

Balmy Spring

Not only was March abnormally mild, but the “summer in March” was unprecedented. A huge high pressure ridge built up over the eastern half of the country, pushing the jet stream well to the north, allowing warm air to gush northward. Both the longevity and the “severity” of the warmth were historic. From March 12–24, temperatures rose into the 70s and even 80s from the northern Plains to New England, shattering records for daily high temperatures, warmest temperatures so early in the season, and warmest temperatures for the month. Readings ranging from 20 to more than 35 degrees above normal were commonplace during this period, as thousands of records fell to the wayside.

The extended warm spell propelled the month to the warmest March in 118 years of record-keeping in the Lower-48, with 25 states in the central and eastern parts of the nation boasting their warmest March. National temperatures averaged 8.6°F above the 20th-century mean, making this one of the most anomalous warm months ever. The March warmth contributed to the warmest meteorological spring (March-May) in 118 years.

The warmth and widespread lack of snow last winter and early spring saved homeowners money on heating costs, but winter recreation suffered, as some ski areas in New England reported revenues down by 25 percent, and resorts were forced to shut down early from the Rockies to New England.

The abnormal warmth confused plant life, sparking premature growth of shrubs and flowers. In Washington, D.C., daffodils bloomed during the first half of February.

The lack of snow and cold also encouraged the premature emergence of more sinister things. By March, the woods and tall grass became no-go zones in deer country for hikers across the Northeast, and especially New England, due to the abundance of deer ticks, some of which carried Lyme disease.

Ironically, spring also featured a Nor'easter (April 22–23) that brought up to a foot of snow to higher elevations in the Northeast interior, so a snow-starved winter ended up being bookended by out-of-season snows in October and April.

With April temperatures near normal over parts of the East, many localities recorded temperatures lower than in March—a strange and unusual reversal in Nature's typical springtime rhythm. The relative cold in April caused early-blooming fruit trees in the Midwest and Northeast to sustain damage from freezing temperatures.

April also saw its share of severe weather events. Tornadoes tore through the Dallas-Fort Worth area on April 3, while baseball-sized hail struck planes at the DFW airport. Slow-moving thunderstorms on April 11 brought a deluge of hail and rain to the Texas Panhandle. A highway near Amarillo shut down after heavy rain pushed hail into 3–4 foot drifts. Just three days later, tornadoes struck Oklahoma, Kansas, and parts of Nebraska and Iowa, with EF-3 damage in Wichita, Kansas. An EF-4 in Central Kansas stripped the bark off of trees, and a weaker tornado left six people dead in Woodward, Oklahoma. On April 29, when severe thunderstorms hit the Saint Louis area, high winds blew over a tent housing a beer garden south of Busch Stadium, injuring around 100 people and killing one. This was part of an April 28–29 severe weather outbreak across the Midwest, Plains, and Southeast that included 34 reports of hail at least two inches in diameter. Total damages from hail and wind rose to a startling $4.25 billion.

Nevertheless, the onset of drought during late spring and summer caused a sharp drop-off in tornado activity. The annual twister count of 936 ranked 2012 only 25th since 1950.

Farther west, lack of seasonal snow and rain led to expanded drought across a large chunk of the West. October-April precipitation totaled less than 70 percent of normal from Southeast Oregon to Colorado and southward to Arizona and New Mexico. April 1 mountain snow pack was largely one-half of normal in this region. The lack of snow plus the warm spring brought dangerous wildfire conditions to the West, especially in Colorado, Utah, Arizona, and New Mexico during spring and early summer, and in Idaho, Wyoming, Oregon, and California later in the summer.

In contrast, enormous piles of snow created problems during winter and early spring in Southern Alaska, as communities ran out of space and residents battled drifts to get into their homes. In early January, heavy snow caused at least three buildings to collapse or partially collapse in the fishing village of Cordova. Valdez reported a monumental depth of 100 inches on March 6, and still held onto 82 inches on March 31.

Elsewhere, winter and spring rains erased drought over much of Texas, but drought lingered in the Southeast. Streams were far below normal over much of Florida into June, but Tropical Storm Debby changed that in a hurry. The earliest fourth named storm on record became nearly stationary in the eastern Gulf of Mexico on June 23–26, causing heavy bands of rainfall to soak the Florida Peninsula and eastern Florida Panhandle. Rainfall totals of 5–10 inches across the state triggered widespread street flooding. The heaviest rains struck Wakulla County south of Tallahassee, with locally over 20 inches.

Epic Heat and Drought

June-July heat and dryness led to the worst Midwest drought since 1988. June rainfall was less than one-fourth of normal in parts of Indiana and Illinois. In Indianapolis, Indiana, June rainfall totaled a record 0.09 inches. June 28 was its 24th day without measureable rainfall, breaking the June record for most consecutive dry days.

The growing Midwest drought merged with the ongoing western drought, leading to one of the most extensive droughts in the United States since the 1930s dust bowl, with 62 percent of the country in drought by the end of July as measured by the Palmer Drought Index—the greatest area since 1939.

In Western New Mexico, the lightning-sparked Whitewater-Baldy blaze began May 16 and continued into late June, burning over 297,000 acres and setting a record as the largest fire in the state's modern history, surpassing a record set just last year. In Colorado, the High Park blaze west of Fort Collins, triggered by lightning on June 9, burned over 87,000 acres and destroyed 191 homes.

The historical heat wave that affected much of the nation in June and July progressed in several stages. Extreme heat initially spread across the High Plains from Montana to Texas during June 22–27, with temperatures reaching the century mark across this region, and even hitting 110°F in Kansas. June 26 was the fifth consecutive day of 100-degree temperatures in Denver, Colorado. The thermometer soared to 105°F on June 25 and 26 in the mile-high city, tying its all-time record. Relative humidity during the heat wave dipped to five percent in Colorado, leading to extreme fire danger.

Strong winds on June 26 whipped a fire near Colorado Springs out of control; the nightmarish conflagration ultimately consumed 146 homes, making this Colorado's most destructive fire.

Triple-digit heat migrated eastward during late June, engulfing most of the eastern half of the nation in July, and then retreating to the central states in late July before finally ending in early August. By any measure, this was one of the most severe heat waves on record, setting numerous daily and monthly heat marks and several all-time benchmarks as well. The July average United States temperature edged out July 1936 as the hottest month ever measured since such records began in 1895.

Thermometer readings from late June into early August were almost unbelievable. The June 29 reading of 104°F in Washington, D.C., was unprecedented for June. Chicago, Illinois, noted 102°F on July 4 and 103°F on both July 5 and 6. In Missouri, Saint Louis sweltered in triple-digit heat for 10 consecutive days to July 7, the longest such streak since 1936. Later in the month, the mercury soared to 108°F on July 25. Nashville, Tennessee, broke its all-time record with 109°F on June 29, as did Atlanta the next day (106°F). A reading of 113°F in Columbia, South Carolina, on June 29 established the all-time mark for the state.

The historic band of severe thunderstorms that raced across the Midwest and mid-Atlantic on June 29 did little to ease the heat and left millions without power in the sweltering heat for days on end. The derecho—one of the most severe to ever strike North America—with winds to 60–70 mph and greater, began in the Illinois area and tracked eastward into Indiana and Ohio. The derecho maintained its ferocity crossing the Appalachians, knocking out power to much of the Washington, D.C., area. From Illinois to Delaware, tumbling trees and limbs left more than 4 million households and businesses without power, in many instances for three or more days. Lack of refrigeration in homes and supermarkets left tons of food rotting, and lack of air conditioning had residents scrambling to find beds with friends and relatives.

The heat returned to the Plains states in late July and early August, causing some locations in Oklahoma to endure up to 19 consecutive 100-degree days through August 4. Oklahoma City experienced 112°F on both August 1 and 2, finally setting an all-time record of 113°F on August 3.

A welcomed frontal passage ended the heat for the Plains and later the East during August 4–5, although abnormal heat dominated the West this month, contributing to massive wildfires, especially in Nevada, Idaho, and California. Fires charred more than 3.6 million acres in the United States during August, setting an August record.

Although August rains from Isaac and other weather systems improved conditions for pastures and some crops, corn and hay took big hits from the drought, with the Unites States Department of Agriculture calling this the “nation's worst agricultural calamity since 1988.” Corn production plummeted 27 percent from early-season forecasts. Dollar losses to corn, soybeans, sorghum, and hay totaled some $33 billion, making this the most expensive agricultural drought in nominal dollars.

Although Isaac was overshadowed by Sandy two months later, residents on the Gulf will remember Isaac for some time to come. At tropical storm strength, the storm entered the eastern Gulf on August 26. Isaac continued on to make landfall twice in Southeastern Louisiana on August 28–29 as a category 1 storm. The reinforced levies held in New Orleans, but other communities found themselves submerged in up to 10 feet of water. About 900,000 homes and businesses were left without power in Louisiana, and damages across the region added up to $2.35 billion. Isaac dumped up to 22 inches of rain on Mississippi. The storm was blamed for five deaths in the United States.

Superstorm Sandy

There is something about October 29. “Superstorm Sandy” struck New Jersey exactly four months after the historical derecho rampaged across the East, exactly one year after the historical “Snowtober” storm, and exactly 11 years after Hurricane Grace collided with a cold front southeast of Nova Scotia, leading to the sinking of the Andrea Gail as described in the book and movie The Perfect Storm. As Hurricane Sandy tracked northeastward parallel to the Southeast coast on October 27–28, an upper-level trough and cold front interacted with the storm, pulling her northwestward into New Jersey on October 29. Sandy became extra-tropical before making landfall near Brigantine, New Jersey. The rise in water (storm surge plus tide) of 13.88 feet at New York City's Battery Park shattered all previous records. The ensuing flood damage to the subway system was unprecedented, as were so many other impacts and aspects of “Superstorm Sandy.” The Jersey coastline was devastated, with some 346,000 housing units damaged or destroyed. In New York, the high surf and damaging winds damaged or destroyed 305,000 housing units. Winds of 80–90 mph took down trees and powerlines along the New Jersey and New York coastal areas, while winds gusting to 50–70 mph knocked out power from Indiana to Maine. Some 8.5 million customers lost power at one point, making this the second greatest weather-related power outage of all time in the United States. Air transportation ground to a halt, with over 18,000 flights cancelled. Record snows piled up in the higher terrain to the west of the storm in Maryland, West Virginia, and Tennessee. Even farther west, Sandy's winds whipped up 20-foot waves on Lake Michigan. Estimated direct losses equaled or exceeded $60 billion, making “post-tropical cyclone Sandy” the second most expensive storm to ever strike the United States (exceeded only by Hurricane Katrina in 2005). Sandy was blamed for 72 direct deaths, including 48 in New York.

In the “adding insult to injury” category, a fierce Nor'easter brought strong winds and up to a foot of snow to the damaged areas of New York and New Jersey on November 7, bringing renewed power outages.

Stormy November and December

Several giant storm systems plagued large parts of the nation in November and December.

A series of low pressure areas and cold fronts penetrated the West Coast during November 27-December 5, bringing very heavy rains and strong winds to the region. Up to 23 inches of rain deluged Northern California, and 150-mph winds blasted Mammoth Mountain ski area. As much as 46 inches of snow buried California ski areas.

On December 9–10, a storm dumped 10–17 inches of snow from South Dakota to Minnesota, resulting in hundreds of road accidents.

From December 17–21, a massive storm system tracked from the West Coast to the East Coast, bringing heavy snows to the West and blizzard conditions to Iowa, Wisconsin, and Northwest Illinois. In Washington, Paradise Ranger Station measured 54 inches of snow on December 18. Nationwide, over 1,000 flights were cancelled, mainly on December 20. Tornadoes across the South caused destruction in Arkansas and Alabama, including Mobile. Up to 20 inches of snow fell around Madison, Wisconsin.

Still another massive storm system swept across the Plains, South, Midwest, and East on December 24–27. This one brought heavy snow as far south as Texas and Arkansas and blizzard conditions from Western Kentucky to Ohio. On Christmas Day, the National Weather Service at one point posted weather watches, warnings, or advisories for at least 27 states from New Mexico to Maine. Twisters on Christmas struck Texas, Louisiana, Mississippi, and Alabama, resulting in the worst Christmas Day tornado outbreak on record. A tornado struck Mobile, Alabama, for the second time in 5 days.

The December storms put down widespread snow cover, unlike the year before. Ironically, the warmest year on record across the continental United States ended with 62 percent of the nation covered by snow, the greatest New Year's Eve extent in at least 10 years.

Top 10 U.S. Weather Events 2012

The weather event rankings consider the following: rarity (once every decade, 100 years?), geographical extent (local? regional? national?), monetary impact (costs exceeding $100 million? $1 billion?), duration (days, weeks, months?), and socioeconomic impacts (fatalities, injuries, power outages, transportation, evacuations, homelessness, etc.).

1. Superstorm Sandy. October 28–29. Category 1 Hurricane Sandy transitioned into a monstrous extratropical storm while making landfall along the New Jersey coast, resulting in one of the most intense and damaging East Coast storms of all time. Surging Atlantic waters (8–14 feet) inundated the Jersey shore and low-lying areas of NYC and Long Island, causing estimated damages of at least $60 billion. The storm caused 72 direct deaths (87 indirect) in the United States, the loss of power to 8.5 million homes and businesses, and the cancellation of more than 18,000 airline flights.

2. Midwest Drought. June-August. Hot, dry weather led to the most intense drought since 1988 over the Corn Belt, wilting crops, drying up pastures, shrinking lake and river levels, and lifting commodity prices to record levels. By mid-July, severe to extreme drought gripped nearly the entire Corn Belt from Nebraska to Ohio, causing over $30 billion in agricultural losses. Nationwide, this was the most extensive drought since 1939.

3. Summer Heat Wave. June 22-August 4. Extreme heat that began over the High Plains, expanded to the East Coast, and then centered on the Heartland broke thousands of temperature records and resulted in July 2012 edging out July 1936 as the hottest month on record for the contiguous United States. The heat, which was blamed for over 100 deaths, contributed to the drought that affected much of the country.

4. Southern Tornado Outbreak. March 2. Dozens of tornadoes ripped across 12 states, killing 40 people, including 13 in Indiana and 22 in Kentucky. Damages exceeded $4 billion.

5. Mid-Atlantic and Midwest Derecho. June 29. The widespread severe winds associated with the band of rapidly moving thunderstorms (a derecho) left a trail of destruction from Illinois to the mid-Atlantic, leaving some 4.25 million homes and businesses without power, killing 24 people, and costing hundreds of millions of dollars in property damage.

6. Hurricane Isaac. August 28–29. Category 1 Isaac made landfall in Southeast Louisiana and moved slowly northward across the state bringing heavy rain and flooding to Louisiana and Mississippi. Five died, some 900,000 customers lost power in Louisiana, and losses totaled $2.35 billion.

7. Summer in March. A record warm March, featuring a summer-like heat wave that broke thousands of records and contributed to the warmest spring (March-May) on record for the Lower 48.

8. Mild Winter. December-February warmth made this the fourth mildest winter in over 100 years across the contiguous United States, which also experienced the third smallest snow cover extent.

9. February Tornado Outbreak. February 28–29. One of the deadliest February outbreaks on record, Kansas to Indiana, took 15 lives.

10. Western Drought. Winter-summer. Abnormal spring warmth plus a dearth of winter season snowfall contributed to severe drought across much of the southwestern quadrant of the nation, contributing to enormous wildfires from Oregon to Colorado.

Weatherwise Contributing Editor DOUGLAS LECOMTE is a retired meteorologist formerly with NOAA's Climate Prediction Center in Camp Springs, Maryland.


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