Historic Heat Wave Reponsible for Death Valley's 129°F Gradually Weakening

One of the greatest heat waves in North American history peaked on Sunday and Monday, but will still bring some of the hottest temperatures ever recorded to portions of the Western U.S. during the afternoon today. The extraordinary heat wave, caused by an unusually extreme standing wave pattern in the jet stream, brought Earth's highest June temperature ever recorded on Sunday, June 30, when the mercury hit 129.2°F (54.0°C) in Death Valley, California. The only higher temperatures ever recorded on the planet occurred in Death Valley on July 10, 12, and 13, 1913, when readings of 134°F, 130°F, and 131°F were recorded. This 100 year-old record heat wave has many doubters, though, including Mr. Burt, who noted in a 2010 blog post that "The record has been scrutinized perhaps more than any other in the United States. I don't have much more to add to the debate aside from my belief it is most likely not a valid reading when one looks at all the evidence. Normally when Death Valley records its hottest temperatures they occur during region-wide heat waves. On July 10, 1913 the next highest temperatures recorded in southern California (aside from Greenland Ranch) were just 119° at Heber and 118° at Mammoth Tank." If Mr. Burt is correct, then this Sunday's temperature of 129.2°F in Death Valley was the hottest temperature in recorded history on Earth.


Figure 1. The official Furnace Creek, Death Valley maximum recording thermometer for the maximum temperature measured on June 30th, 2013. The 129.2°F reading was the highest June temperature ever measured on Earth. Photo courtesy of Death Valley National Park and NWS-Las Vegas.

As documented by Mr. Burt in this latest blog post, some of the all-time records from the 2013 heat wave:

June 27, 2013
102° Santa Fe, NM: all-time heat record
105° Albuquerque, NM: tied 2nd highest temperature on record

June 28, 2013
105° Salt Lake City, UT: hottest June temperature on record
114° Zion National Park, UT: hottest June temp on record, and only 1° short of their all-time record of 115°

June 29, 2013
100° Ely, Nevada: hottest June temperature on record (previous 99° June 22, 1954)
101° Eureka, Nevada: hottest June temperature on record (previous 98° on two occasions)
105° Salt Lake City, Utah: hottest June temperature on record (again, see June 28)
122° Palm Springs, California: hottest June temperature on record (tied June 28, 1994) and 1° short of all-time record of 123° set on August 1, 1993
128° Death Valley, California: hottest June temperature on record (tied previous 128° set on June 29, 1994)
It was 119° in Phoenix, Arizona their 4th warmest reading on record.

June 30, 2013
129° Death Valley, California: Earth's all-time hottest June temperature
115° Lancaster, California: all--time heat record (previous record 114° on July 18 and 19, 1960)
117° Las Vegas, Nevada: all-time heat record (tied with July 19, 2005 and July 24, 1942)

All-time June monthly records were set or tied at:
104° Elko, Nevada (previous 104° June 24, 1981)
103° Tonopah, Nevada (previous 102° on two occasions), this was also just 1° short of their all-time record of 104° set on July 18, 1960).
106° Winnemucca, Nevada (previous 106° on June 24, 1988)

July 1, 2013
127° Death Valley, California
110° Boise, Idaho: tied for 2nd hottest temperature on record

Deadly Yarnell, Arizona fire continues to burn out-of-control
The deadly Yarnell Hills, Arizona wildfire that claimed the lives of nineteen firefighters of the Prescott-based Granite Mountain Hotshots continues to burn out of control near Yarnell, a small town about 85 miles northwest of Phoenix. The fire has burned 8,400 acres (13 square miles) and was 0% contained on Tuesday morning. Temperatures in the upper 90s are expected Tuesday afternoon near Yarnell. These temperatures are about five degrees cooler than during Sunday's deadly blaze. The intense ridge of high pressure responsible for the intense heat will continue to weaken during the week, and high temperatures will be in the low 90s by the end of the week.


Figure 2. The Yarnell Hill Fire burns through the town of Yarnell, Ariz. on Sunday, June 30, 2013. The fire started Friday from a lightning strike and killed nineteen firefighters on Sunday. (AP Photo/The Arizona Republic, Tom Story)

Radar imagery from Sunday showed numerous dry thunderstorms over the Yarnell area, and it is likely that the outflow from one of these thunderstorms caused a sharp wind shift and strong wind gusts that caused extreme fire behavior that overran the firefighters' escape route. According to The Arizona Republic, the firefighters were trapped between two ridges when the winds suddenly reversed. A fire-monitoring station four miles from the fire measured nearly record combustion levels for the fuel on the ground, in the 97th percentile since the station was installed in 1985. The station measured southwest winds gusting to 15 to 25 mph at 4:01 PM. One hour later, ten minutes after the firefighters had deployed their fire shelters, the wind had reversed direction to northeast, and was gusting at 30 to 47 mph. The topography could have channeled these wind gusts to even higher speeds where the firefighters were. "Guys on the ground told me the fire behavior was as extreme as anything they’d ever seen,” said Dugger Hughes of the Southwest Coordination Center, an interagency organization in New Mexico that coordinates state and federal firefighting resources. The flames were 40 feet high and moved at an average speed of 1/2 mph. According to WWF blogger Nick Sundt, who is a former "smokejumper", dry thunderstorms causing sudden wind gusts and wind shifts is a common scenario with such large scale firefighter fatality incidents: for example, in the 1949 Mann Gulch fire in Montana (thirteen firefighters killed), and in the 1994 Storm King Mountain or South Canyon Fire in Colorado (fourteen firefighters killed.) Nick commented in an email to me: "It happened once to me in Idaho late one afternoon (in 1981, I think) when gusts from a building thunderstorm caused a fire to blow up in a drainage I was in with other smokejumpers.  We popped our fire shelters but the winds shifted late in the night and the fire stopped short of us. We high-tailed it out of there early in the morning before the winds picked up and incinerated everything we left behind (parachutes, jump gear, etc)." Wunderblogger Lee Grenci analyzes the 3-dimensional characteristics of the atmosphere over Arizona over the weekend in his latest post. He shows how conditions were ideal on Sunday for spawning dry thunderstorms capable of bringing erratic, gusty winds to the fire region. Here is the "Spot Forecast" that the Granite Mountain Hotshots had to work with on Sunday:

FNUS75 KFGZ 301655
FWSFGZ

SPOT FORECAST FOR YARNELL HILL...ARIZONA STATE FORESTRY
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
945 AM MST SUN JUN 30 2013

FORECAST IS BASED ON REQUEST TIME OF 0939 MST ON JUNE 30.
IF CONDITIONS BECOME UNREPRESENTATIVE, CONTACT THE NATIONAL WEATHER SERVICE.

DISCUSSION...STRONG HIGH PRESSURE OVER THE SOUTHWEST WILL MAINTAIN THE HEAT SPELL FOR THE NEXT SEVERAL DAYS. LIMITED MOISTURE WILL RESULT IN ISOLATED THUNDERSTORM ACTIVITY TODAY AND MONDAY. THESE STORMS WILL PRODUCE LIGHTNING AND STRONG AND GUSTY WINDS...BUT LITTLE OR NO MEASURABLE PRECIPITATION. TEMPERATURES WILL DECREASE SLIGHTLY AND MINIMUM RELATIVE HUMIDITY WILL SLOWLY INCREASE OVER THE NEXT FEW DAYS.

TODAY...

SKY/WEATHER.........PARTLY CLOUDY. A SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS IN THE AFTERNOON.
MAX TEMPERATURE.....100 TO 103.
MIN HUMIDITY........11 TO 15 PCT.
WINDS (20 FT).......EAST WINDS AROUND 5 MPH...BECOMING SOUTHWEST
WITH GUSTS UP TO 20 MPH IN THE AFTERNOON.
LAL.................2.
HAINES INDEX........5 MODERATE.

TONIGHT...

SKY/WEATHER.........PARTLY CLOUDY. A SLIGHT CHANCE OF SHOWERS AND
THUNDERSTORMS IN THE EVENING.
MIN TEMPERATURE.....73 TO 76.
MAX HUMIDITY........35 TO 40 PCT.
WINDS (20 FT).......WEST WINDS AROUND 10 MPH. GUSTS UP TO 20 MPH
EARLY IN THE EVENING.
LAL.................2.
HAINES INDEX........5 MODERATE.

MONDAY...

SKY/WEATHER.........PARTLY CLOUDY. A SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS IN THE AFTERNOON.
MAX TEMPERATURE.....98 TO 102.
MIN HUMIDITY........13 TO 17 PCT.
WINDS (20 FT).......SOUTH WINDS AROUND 5 MPH...BECOMING SOUTHWEST WITH GUSTS UP TO 20 MPH IN THE AFTERNOON.
LAL.................2.
HAINES INDEX........5 MODERATE.

$$
FORECASTER...DB
REQUESTED BY...BYRON R KMIBALL
REASON FOR REQUEST...WILDFIRE
TAG 20130630.YARNE.01/FGZ

The shocking and sad deaths of the nineteen brave men who died on Sunday was the largest loss of life among wildfire firefighters since 1933 Griffith Park, California fire in the U.S. (25 killed.) Fighting wildfires is dangerous work, and 1,043 firefighters died between 1910 - 2012 fighting wildfires in the U.S., according to statistics from the National Interagency Fire Center. Firefighter deaths have been on the rise in recent decades. Over the past ten years, 2004 - 2013, there have been an average of sixteen of these deaths per year, compared to eleven deaths per year during the 1970s and 1980s.

Links
Experts See New Normal as a Hotter, Drier West Faces More Huge Fires New York Times, July 1, 2013
The Climate Context Behind the Deadly Arizona Wildfires Climate Central, July 1, 2013

The tropical Atlantic is quiet
There are no threat areas in the Atlantic to discuss today, and none of the reliable forecast models predict tropical cyclone development through Sunday. There is a large upper-level cold-cored low pressure system over the middle of the North Atlantic that will move to the southwest during the week, and this low is expected to arrive in the Bahamas by Sunday and bring rainy conditions. Although the models do not show that this low will will acquire a surface circulation and develop tropical characteristics, it may be worth watching for development late this week.

Jeff Masters