The colored rectangular image shows the sea surface temperature anomalies across the central Pacific Ocean for the past four weeks. The white areas on either side of the image indicate the Americas (right) and Australia (bottom left). The deep oranges and reds show areas where the water temperature is between 1-2 degrees Celsius above average (2 to 4 degrees Fahrenheit). This water temperature pattern is a classic sign of El Niño and has effects on the weather in the United States.

 

Sea surface temperature anomalies across the central Pacific Ocean (courtesy NOAA).

To get an idea how this will effect temperatures during the late fall and early winter in Virginia, we look back in the climatological record for times in which the El Niño was in place. There are 10 years in particular which area good match for this situation. They are indicated from the second graphic (courtesy NOAA).

(Graphic courtesy of NOAA)

The composite of these 10 years indicates the average temperature for the state is 1.5 to 2.0 degrees above the long-term average for the 60-day period encompassing November and December. Notice in the very strong El Niño year of 1982, the temperature for that period was about 4 degrees above normal.

The El Niño building now is strong-to-moderate in intensity, and it continues to strengthen, so it stands to reason we may need to rethink our forecast a few weeks ago for a cold December. It appears more likely that temperatures will be close to or moderately above normal. 

Any meteorology textbook or weather website will list the “Official” Hurricane Season in the Atlantic Ocean as between June 1st and November 30th. Further, the text book will explain that the most active period is in September. However, nature doesn’t like to follow rules, and sometimes, storms form very early or late in the designated “season” and sometimes, tropical storms even occur outside of the tropical season altogether. This is rare, but does happen, for example, in 2005; the number of named storms exceeded the alphabet. Do you remember Tropical Storm Zeta over New Years?

Early season storms and late season storms have different characteristics than traditional, middle of the season tropical cyclones. This is due to different initial conditions in the atmosphere when the storms develop. A late season storm, like Ida, has a much different kind of origin and behavior. Late in the fall, the Gulf of Mexico is still holding onto the heat of the summer. But as the temperatures over the land drop and cool fall rains soak into the continent and wash out into the gulf, the shallow water near the shore cools before the deeper water far from shore. That is because of cooler rain runoff over the land chills the near shore water first. So, it is typical to have deep ocean warmth in the center of the Gulf of Mexico well into the late fall, but the water temperatures in the northern gulf are too low to sustain a growing hurricane. Water should be at least 80 degrees Fahrenheit.

Another reason for the relatively few late season tropical cyclones is the position of the jet stream. In the summer, the jet stream is far to the north. That means over much of the southern half of the USA, winds even at higher altitudes are not particularly strong. So, as a cluster of thunderstorms develops into a tropical storm over warm ocean waters, the winds at the higher levels won’t act to pull apart the storm.

In the fall, the jet stream often will dive far south and bring cold air from Canada deep into the south. These intrusions mark the changing of the seasons, but every time cold air dives south, also diving south are stronger westerly winds from the polar jet stream. This combination of stronger winds and cooler water over the gulf push the zone where tropical storm formation can develop further south into the Caribbean Sea.

This is where Ida got its strength. Ida strengthened of the coast of Central America in some still very warm water and light upper level winds. After soaking parts El Salvador and Honduras, Ida did move north into the central Gulf of Mexico. In those warm waters, Ida did strengthen to a Category 2 storm with winds over 100 mph in the southern Gulf before encountering stronger upper level winds and cooler waters over the northern Gulf of Mexico.

As cooler and drier air got incorporated into the circulation of Ida, the storm lost its “tropical” characteristics and attained a comma shape. Cold fronts and warm fronts could be picked out of the storm. By Friday, Ida will have moved away from the area, as a classical looking “nor’easter” type storm bringing heavy rain and strong wind to the Mid-Atlantic and New England for the weekend. A strong nor’easter can be more damaging than a hurricane with potential for beach erosion and flooding.

 

 

 

 

Chip Maxham

ABC 13 Meteorologist

From November 5^th through the 12^th the Earth will be entering a stream of debris from a comet known as 2P/Encke.  This will bring us the annual Taurid Meteor Shower.  Each night (especially around the midnight hour) about 5 Taurids per hour will shoot from the constellation Taurus straight overhead.  While this is not as many as an average meteor shower, the Taurid meteors are remarkable in other ways!  Many stargazers have observed the Taurids to be very bright and slowing fireballs in the sky.  Below are a few stories submitted to NASA after the 2005 Taurid Meteor Shower, which happened to bring many -- a big show.

 

 

-On Oct 28, Lance Taylor of Edmonton, Alberta, woke up early to go fishing with five friends. At about 6 a.m. they "noticed a nice fireball. Then 20 minutes later there was another," he says.

-On Oct. 30, Bill Plaskon of Jonesport, Maine, was "observing Mars through a 10-inch telescope at 10:04 p.m. EST when a brilliant fireball lit up the sky and left a short corkscrew-like smoke trail that lasted about 1 minute."

-On Nov. 2 in the Netherlands, "The sky lit up very bright," reports Koen Miskotte. "In the corner of my eye I saw a fireball about as bright [as a crescent moon]."

 

 

 

This year keep your eyes peeled toward the night sky, as you may happen to sight one of these spectacular occurrences!