Death Valley National Park is famous for being the hottest, driest, and lowest place in the United States. The interesting thing about all these extremes, as I learned during a recent visit, is how they interconnect.
Situated in eastern California near the Nevada border, the park’s topography is known as basin and range. This is where the earth’s crust is rifting apart, creating mountains in some areas and deep basins in others. Death Valley is a long, narrow basin that reaches a depth of 282 feet below sea level. It is also in the rain shadow of four different mountain ranges to the west – the Coastal Range, the Sierra Nevada, the Argus Range, and the Panamint Range.
As storms move inland from the Pacific, they must rise up and over each range. In doing so, they cool and their water vapor condenses into rain or snow that falls on the western side of these mountains. By the time a storm system reaches Death Valley, it has lost most of its moisture. The average annual rainfall in the park, according to NOAA, is just 2.36 inches.
These dry conditions, along with the valley’s below-sea-level elevation, help to produce the park’s famous heat. With cloud free skies and sparse vegetation, a maximum amount of sunlight can reach the ground. The rocks and parched soil absorb the heat and radiate it into the air. The warm air rises but becomes trapped by the steep valley walls. After cooling slightly, it is recycled back toward the valley floor where it is heated even further by atmospheric compression. During the summer months, this process generates hot winds and sizzling temperatures. The average high temperature in the park ranges from 67°F in January to 116°F in July. The hottest temperature ever recorded was 134°F on July 10, 1913 – a world record.
Looking ahead, as the climate changes, the southwestern region of the US is expected to become even hotter and drier. It seems like only a matter of time before Death Valley breaks its own heat record.
At 282 feet below sea level, Basin in Death Valley National Park is the lowest point in the US. Credit: Melissa Fleming
Over the past week, a cavalcade of intense rain and snowstorms battered the west coast of the US and put a major dent in California’s five-year drought.
According to the latest report from the US Drought Monitor, the northern third of the Golden State is now drought free. This is a major change from just three months ago, when the entire state was in some form of drought.
Across the region, copious amounts of precipitation were reported. More than a foot of rain fell in the Sierra Nevada, with 20.7 inches measured locally at Strawberry Valley, CA. Higher elevations saw tremendous snowfall totals. Heavenly Ski resort in South Lake Tahoe, according to the NWS, received an incredible 12 feet of snow in just one week.
These staggering totals came courtesy of a weather phenomenon known as an “atmospheric river”. These are narrow, but intense bands of water vapor sourced from the tropics. Often originating near Hawaii, this fire hose of moisture is sometimes called a “pineapple express.”
While this excessive rainfall did cause flooding events across the region, reservoir levels have benefited. Lake Shasta, the largest largest reservoir in California, is currently at 81% of total capacity and 126% of its historical average for the date.
Southern California also picked up some much-needed rainfall, but still remains in drought. That said, only 2% of the state is currently in exceptional drought, the worst possible category.
Northern California is drought free for the first time in five years. Credit: US Drought Monitor
The world of weather has some interesting words and phrases. One of these is “Rain Shadow”.
While it sounds rather poetic, a rain shadow refers to the land area on the leeside of a mountain that is exceptionally dry. Mountains act as barriers for weather systems traveling in a region’s prevailing winds, forcing them to drop most of their moisture on the windward side before they can pass.
As an air mass rises up and over a mountain, it enters an area of lower atmospheric pressure where it expands and cools. As a result, the moisture it contains condenses, clouds form, and precipitation falls. After the air mass moves over the mountain, it starts to descend the other side. The air is warmed by compression and the clouds dissipate. This means little to no rain falls on the leeward side.
Rain shadows are found all over the world, from the Tibetan Plateau in Asia to the Atacama Desert in South America. Here in the US, Death Valley is a famous example as it lies in the rain shadow of four different mountain ranges.
The Rain Shadow Effect. Credit: Kagee Commons
November felt like a weather roller coaster in New York City this year. We had highs that ranged from a relatively balmy 72°F to a chilly 41°F. However, with 19 out of 30 days posting above average readings, the warmth won out in the end. The city’s mean temperature for the month was 49.8°F, which is 2.1°F above our long-term norm. This was the Big Apple’s 17th consecutive month with an above average temperature – its longest streak on record.
In terms of precipitation, November was unusually wet and marked the first month since July that NYC received above average rainfall. In all, we received 5.41 inches of rain which is 1.39 inches above normal. The majority of this plentiful total fell during two separate heavy rain events. In fact, November 29th was the city’s wettest day of the year and set a new daily rainfall record with 2.20 inches measured in Central Park. Nonetheless, despite these soakers, NYC remains in a moderate to severe drought according the latest report (12/1) from the US Drought Monitor.
November 2016 was NYC’s 17th consecutive month with an above average temperature. Credit: The Weather Gamut
November was the first month since July that NYC received above average rainfall. Credit: The Weather Gamut
A rainy day in New York City is typically nothing to write home about, but Tuesday’s precipitation was extreme. Heavy downpours brought the city more than half a month’s worth of rain in a single day.
According to the NWS, 2.2 inches of rain was measured in Central Park. Not only is that a new daily record for the date, it was the wettest day the city has seen so far this year. On average, we normally get 4.02 inches of rain for the entire month of November.
Suffering through moderate to severe drought conditions for several months, this rainstorm was largely beneficial for the area even if did put a damper on the Rockefeller Center Christmas Tree Lighting Ceremony. That said, even more rain is needed to bust this drought completely. Year to date, the city’s rainfall deficit is 7.24”.
This type of heavy rain event, according to NOAA, is expected to become more common in the northeast as global temperatures rise and precipitation patterns change.
October felt like a weather roller coaster in New York City this year. We had highs that ranged from a balmy 85°F to a chilly 51°F. But, in the end, the warmth won out. The city’s mean temperature for the month was 58.8°F, which is 1.9°F above our long-term norm.
On the precipitation side of things, the city received near average rainfall for the first time in months. In all, we received 4.15 inches of rain in Central Park, which is only 0.25 inches below normal. Of this total, 1.41 inches fell during a single heavy rain event on October 27th – the city’s wettest day since last May. Despite this soaker, the Big Apple remains in a moderate to severe drought according to the latest report (released on 10/27) from the US Drought Monitor.
October was a temperature roller coaster in NYC. Credit: The Weather Gamut.
Rainfall was near average in NYC for the first time in months. Credit: The Weather Gamut
Hurricane Matthew, the 13th named storm of the Atlantic Hurricane Season, hammered the southeastern United States this weekend from Florida to Virginia.
Tearing up the coast as it trekked northward, Matthew made landfall near McClellanville, SC on Saturday as a category-1 hurricane with 75mph winds. It had reached category-5 status in the Caribbean – the first storm to do so since Hurricane Felix in 2007- but weakened as it moved toward the US.
Despite this downgrade, Matthew still packed a powerful punch. Its strong winds, flooding rains, and storm surge caused significant property damage and widespread power outages throughout the region. The death toll from this storm currently stands at 26 people from across five states and is expected to increase in the coming days.
With successive bands of heavy rain, Matthew also caused catastrophic inland flooding. In Fayetteville, NC – 100 miles from the coast – 14.82 inches of rain was reported. As a result, several rivers in the region rose to record or near-record levels and overflowed their banks, inundating communities.
All told, Matthew dumped 13.6 trillion gallons of water on Florida, Georgia, South Carolina, North Carolina, and Virginia before heading out to sea as a post-tropical storm. That is enough water to fill over 20 million Olympic-size swimming pools. The highest rainfall total, 17.49 inches, was reported near Savannah, GA.
The damage caused by Matthew is currently estimated at $6 billion.
Hurricane Matthew batters the southeastern US. Credit: NOAA/NASA
Hurricane Hermine, the eighth named storm and fourth hurricane of the 2016 Atlantic Hurricane Season, made landfall in the Big Bend region of Florida early Friday morning. It slammed the Sunshine state’s west coast from Tampa to Tallahassee with heavy rain and winds measured up to 80 mph.
The category-1 hurricane generated a 9-foot storm surge in Cedar Key and dumped more than 22 inches of rain in parts of Pinellas County, flooding many communities. The storm also downed trees and knocked out power to over 250,000 people. Only one storm related death was reported.
Traveling across Florida, Hermine was downgraded to a tropical storm. It is now in the Atlantic moving north along the eastern seaboard. Impacts such as powerful winds, heavy rain, coastal flooding, and dangerous rip currents are expected to be felt from Georgia to Connecticut this holiday weekend.
Hermine was the first hurricane to make landfall in Florida in eleven years.
Hurricane Hermine makes landfall in Florida on September 2, 2016. Credit: NOAA
July is normally the warmest month on the calendar for New York City, and this year, despite a relatively cool start, was no exception. Overall, 20 out of 31 days posted above average temperatures. These included ten with readings in the 90s, which is four more than what we typically see for the month. Additionally, July produced our first official heat wave of the summer. With overnight lows also running mostly above normal, the city’s mean temperature for the month was 78.7°F, which is 2.2°F above average.
In terms of precipitation, July was unusually wet and marked the first month since February that NYC received above average rainfall. In all, we received a staggering 7.02 inches of rain in Central Park, which is 2.42 inches above normal. The majority of this plentiful total fell on four separate days in the form of intense downpours. Nonetheless, despite these soakers, NYC remains in a moderate drought according the latest report (7/26) from the US Drought Monitor.
July brought NYC ten days with temperatures in the 90s, which is four above average. Credit: The Weather Gamut.
More than seven inches of rain fell in Central Park this July. Credit: The Weather Gamut.
Tropical Storm Colin, the third named storm of the 2016 Atlantic Hurricane Season, made landfall in the Big Bend region of Florida on Monday. It slammed the northern part of the Sunshine state with heavy rain and sustained winds measured up to 50 mph.
According to the NWS, more than 10 inches of rain fell in the Tallahassee area and Gainesville posted its second wettest June day on record with 5.65 inches of rain reported. All this precipitation in such a short period of time caused widespread flash flooding. Storm surge flooding was also an issue for communities along the state’s Gulf Coast.
The storm, according to FEMA officials, downed trees and knocked out power to more than 45,000 people between Tampa Bay and Jacksonville.
Traveling across Florida, the storm transitioned to a “post-tropical” cyclone on Tuesday as it moved up the east coast and out to sea.
Colin was the first named storm to hit the Sunshine state since Andrea in 2013. It was also the earliest “C” storm on record to form in the Atlantic Basin.
Tropical Storm Colin over the Gulf of Mexico on June 6, 2016. Credit: NASA