Monthly Archives: January 2014

South Florida’s Rising Seas – A Documentary

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Sea level rise is one of the most pressing aspects of climate change for coastal communities around the globe.  One of the most vulnerable regions in the United States is southern Florida, which is the subject of the documentary, “South Florida’s Rising Seas”

Produced by Florida International University professors, Kate MacMillin and Dr. Juliet Pinto (a longtime friend), the half-hour production explains the science of sea level rise and explores the potential threats to the region.  It also addresses the actions being taken to help keep South Florida habitable.

The documentary is scheduled to air for the first time on WPBT2 – the public television station for South Florida – at 8PM on January 15th.  It will be followed by a half-hour panel discussion moderated by Helen Ferré, host of WPBT2’s public affairs program Issues, and featuring: John Englander, author of “High Tide on Main Street”; Dr. Hal Wanless, chair of the University of Miami’s Dept. of Geological Sciences; Richard Grosso, Director of the Environmental & Land Use Law Clinic and professor of law at Nova Southeastern University; and Dr. Juliet Pinto, co-producer of the documentary.

To watch the trailer, visit http://journalism.fiu.edu/#!/Spotlight

For those outside the viewing area, the program is available online at http://video.wpbt2.org/video/2365148517/

Weather Whiplash for NYC

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New York City was on a temperature roller coaster this week.  From unseasonably warm to brutally cold, we saw it all.

On Monday, it was 55°F in Central Park.  Then, in a matter of twenty-four hours, from 8 A.M. on Monday to 8 A.M. on Tuesday, the temperature in the city dropped 51°F!  With a low reading of 4°F on Tuesday morning, the Big Apple set a new record low for the date.  This dramatic change was ushered in by a weakened polar vortex and a deep dip in the jet stream.  After a few days of bitterly cold conditions, the mercury climbed above freezing on Friday and then continued to rise. On Saturday, the city’s temperature reached a relative balmy 58°F!  Our average high for this time of year is 38°F.

From the mid-50s to the single digits and back again in a matter of six days, it felt like weather whiplash!  Temperature swings of this magnitude in NYC are very unusual.

Image Credit: The Weather Gamut

Graph Credit: The Weather Gamut

The Dead of Winter

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The deep freeze that gripped much of the U.S. this week has begun to thaw.  The “Dead of Winter”, however, is just beginning.

While actual daily weather varies, this old saying refers to what is statistically the coldest part of the winter season.  Between January 10th and February 10th, average temperatures reach their lowest point of the year in the northern hemisphere.

These few weeks are the climatological opposite of the “Dog Days of Summer“.

The Polar Vortex

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The Polar Vortex has been making headlines across most of the United States recently.  But, what exactly is it?

According to NOAA, the northern hemisphere polar vortex is a high altitude low-pressure system anchored over the Arctic.  More specifically, it is “the pattern of winds around the North Pole.”  It is always present, but tends to be stronger in the winter.

The configuration of the polar vortex – smooth or wavy – determines how much cold air escapes the region. Driven by the temperature difference between north and south, these winds typically circle the pole from west to east in a smooth pattern that bottles up the Arctic’s cold air.   When these winds weaken, the pattern becomes wavy and cold air pushes southward.

The connection between warming conditions in the Arctic (decreasing the temperature difference between north and south) and extreme weather events in the mid-latitudes is an active area of research. Some scientists suggest that increasing Arctic temperatures may be responsible for disrupting the pattern of the polar vortex.

The polar vortex is shown in purple. Image Credit: NOAA

Polar Vortex configuration: Smooth vs Wavy.  Image Credit: NOAA

A Deep Freeze in NYC

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A massive arctic outbreak has sent most of the U.S. into a deep freeze.  From the Mid-West to the Gulf Coast and along the eastern seaboard, many cities are dealing with the coldest temperatures they have seen in nearly two decades.

Here in New York City, the mercury fell to 4°F in Central Park this morning – a new record low for the date.  The previous record of 6°F was set in 1896. Our normal low temperature for this time of year is 27°F.

While it certainly was bitterly cold today, it was not the coldest day the Big Apple has ever experienced. That dubious honor, according to the NWS, belongs to February 9, 1934, when the low was a brutal -15°F.

Our current frigid conditions are the product of a weakened polar vortex – the pattern of winds around the North Pole.  As it slowed down, arctic air pushed southward and caused a deep dip in the jet stream. This frosty air is not likely to stick around much longer, though.  As the jet stream retreats northward, temperatures are forecast to rebound to more seasonable, and even above average, levels by the end of week.

Image Credit: Mesonet

Image Credit: Mesonet

Today is Earth’s Perihelion

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The Earth reached its Perihelion today at 12 UTC, which is 7AM Eastern Standard Time. This is the point in the planet’s orbit where it comes closest to the Sun.

This annual event is due to the elliptical shape of the Earth’s orbit and the off-centered position of the Sun inside that path.  The exact date of the Perihelion differs from year to year, but it’s usually in early January – winter in the northern hemisphere.  The Earth will be furthest from the Sun in July.

While the planet’s distance from the Sun is not responsible for the seasons, it does influence their length.  As a function of gravity, the closer the planet is to the Sun, the faster it moves. Today, the Earth is about 146 million kilometers away from the Sun.  That is approximately 5 million kilometers closer than in early July.  This position allows the planet to speed up by about one-kilometer/second.  As a result, winter in the northern hemisphere is about five days shorter than summer.

The word, perihelion, is Greek for “near sun”.

Image Credit: Academy Artworks

Image Credit: Academy Artworks

First Major Winter Storm of 2014

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The first major winter storm of 2014 blasted a large area of the U.S. overnight. Packing heavy snow, high winds, and bitterly cold air, it impacted nearly twenty states from the Mid-West to New England.

Locally, the storm brought New York City 6.4 inches of powdery snow.  On average, the city usually receives 7 inches for the entire month of January. The storm also sent temperatures plummeting.  The high reading in the Central Park today was only 18°F.  Tonight, the temperature is expected to drop to a frigid 5°F.  When you factor in the wind chill, it will feel like -10°F.  Our normal high for this time of year is 39°F and our normal low is 28°F.

Bow Bridge

Central Park’s Bow Bridge in the snow.  Image Credit: The Weather Gamut.

Winter 2014

View of midtown Manhattan’s skyline from snow-covered Central Park.                                      Image Credit: The Weather Gamut.

 

NYC 2013: The Year in Review

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New York City experienced some noteworthy weather in 2013. We bounced between the extremes of our coldest March in seventeen years and a July with extended heat waves.  In fact, we had 17 days this summer with readings at or above 90°F, which is two above normal.  Despite these superlatives, the city’s average temperature for the year was 55.34°F. That is only 0.5°F above our long-term norm.

Precipitation in the Big Apple this year was erratic. We fluctuated between our second wettest June on record and our third driest October. In the end, though, we were mostly dry. The city received a total of 46.32 inches of rain for the entire year.  That is 3.62 inches below normal.  Snowfall, however, was abundant.  February brought the city a blizzard that dumped 11.4 inches of snow in Central Park.  March and December also delivered above average snow totals.  For the year as a whole, the city accumulated 29.6 inches, which is 4.5 inches above average.

On the storm front, the 2013 Atlantic Hurricane season left NYC unscathed. This was a welcome relief after being hit by major storms two years in a row – Irene in 2011 and Sandy in 2012.

Moving into 2014, we are off to an active start. A winter storm warning is currently in effect for the city as a nor’easter makes its way up the coast.

Graph Credit: The Weather Gamut

Graph Credit: The Weather Gamut

NYC Monthly Summary: December 2013

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New York City experienced a wide array of temperatures this December.  We had highs that ranged from a chilly 30°F to a record warm 71°F.  These extremes balanced each other out in the end, though.  The city’s mean temperature for the month was 38.6°F, which is only 0.65°F above average.

On the precipitation side of things, NYC collected 4.85 inches of rain, which is 0.85 inches above normal.  This was the first time since June that we received above average rainfall. In terms of snow, the city saw 8.6 inches accumulate in Central Park, which is 3.8 inches above average for December.  Most of this fell during a widespread pre-season winter storm in the middle of the month.

Graph Credit: The Weather Gamut

Graph Credit: The Weather Gamut

Graph Credit: The Weather Gamut

Graph Credit: The Weather Gamut