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February 2011
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Solar Flares Ignite Worldwide Sun Watch

posted on Thursday, February 17th, 2011 at 7:35 pm

The National Weather Service, Space Weather Prediction Center, is reporting a solar blast occurred this week, “…prompting a rerouting of air traffic and causing disruptions to high frequency communications.” (National Weather Service) The solar flare is already disrupting radio communications in China. NASA is concerned it could disrupt electrical power grids and satellites used on Earth tonight through Saturday, February 19th.

According to NASA, “On Valentine’s Day the Sun unleashed one of its most powerful explosions, an X-class flare. The blast… was also accompanied by a coronal mass ejection, a massive cloud of charged particles traveling outward at nearly… (sic)  600 miles per second.”  Tonight some of energy from the sun could pass through the earth’s atmosphere and put on a light show for the northern and southern hemispheres. The charged particles excite the oxygen and nitrogen atoms in the earth’s atmosphere, making them glow blue, red, green, or magenta. Chances are most of us won’t see it, but my cousin up in Minneapolis might be lucky enough to see the spectacular display of light!

Solar X-Ray, GOES Satellite

Solar X-Ray, GOES Satellite

Check out this latest solar x-ray image from the GOES 15 satellite program. According to NOAA, or the National Oceanic and Atmospheric Administration, the latest GOES spacecraft carry a solar x-ray imager to monitor the sun for early detection of solar flares and other solar events that impact the earth. It’s an early warning program to try and protect astronauts during space missions, and also military and commercial satellite communications.

Solar Flare 2011

A solar flare in 1989 caused a major blackout in Canada. Concern over the impact of this week’s event have caused air travel to be rerouted

For a current list of solar flare rankings, click here. (This one isn’t at the top of NOAA’s list.) For the latest images from NOAA’s solar x-ray, click  here.

Besides the excitement from the solar flares, the other exciting weather news today was the winter storm warnings for the Sierra. Check out the latest forecasts for Sacramento, Reno.

Biggest Solar Flares in 4 Years Heading Toward Earth

Frame from an animated GIF showing the solar flare in question. [Photo: NASA/Solar Dynamics Observatory]That big massive ball of burning hydrogen in the center of our solar system has been getting more and more active as of late–the sun recently had three solar flares explode from the corona, its high temperature plasma atmosphere. Particularly powerful solar flares produce coronal mass ejections, which can reach temperatures of millions of degrees Fahrenheit at the time of explosion and can eventually reach Earth.

We’re lucky to live on this planet: This round, sweet Earth has a magnetic field that protects us terrestrial inhabitants from a good deal of space weather, including high radiation-charged particles emitted from the Sun during these coronal mass ejections (CMEs). That said, these latest three solar flares were the largest in the last four years, and should put on a spectacular light show when they reach us tonight and on Friday. These flares also mark the ramping up of a new solar cycle, which means we should be seeing more and more solar flares in the next few years.

Most of these charged particles are deflected or trapped by Earth’s magnetic field, but some make it through to our atmosphere and excite the oxygen and nitrogen atoms, making them glow blue, red, green, or magenta, producing the spectacular aurora we can see in northern or southern latitudes (sorry, folks at the equator). These recent solar flares should make for some spectacular aurorae tonight

Here Comes The Fog Again

posted on Tuesday, February 15th, 2011 at 10:03 pm

After an unusually cold and dry winter so far across the Gulf South, the pattern has taken a more typical turn.  High pressure is building back in, winds out of the southeast are setting up, and warmer temperatures are ushering back in, but also so is dense overnight fog.  As the pattern stagnates over the next several days, reduced morning visibilities can be expected across portions  of the Gulf states.  In fact Dense Fog Advisories have been issued for the coast of Southeast Louisiana for visibilities below 1/4 mile at times.  Cities that can expect slow morning commutes are places like New Orleans, Baton Rouge, and Biloxi.

Dense Fog Advisory February 15, 2011, Image: NOAA

Dense Fog Advisory February 15, 2011, Image: NOAA

What’s the deal with this Gulf Coast fog during the Fall, Winter, and Spring?  Well, its something called sea fog and it doesn’t just happen in Louisiana and Mississippi.  In fact, it also occurs in other places in the United States, like San Francisco, and even in other places around the world, like Hong Kong!

Sea Fog Formation, Image: Hong Kong Observatory

Sea Fog Formation, Image: Hong Kong Observatory

Take a look at the image above.  This is what causes sea fog to form.  Winds from a warm and humid source region blow over an area of colder water.  This helps to condense the moisture out of the warm, moist winds as they pass.  This process forms a low cloud.  Those same winds then push the newly-formed cloud over a nearby landmass and voila: fog.

In the case of the Gulf South, these winds are southeasterly and pick up warmth and moisture from the Central Gulf of Mexico, where the deep waters still have temperatures well into the 70s.  These rather tropical winds then run northwestward over shallower near-shore waters, that are much more subject to cooling by the cold wintertime land temperatures.  These coastal waters have temperatures only in the 50s.  This helps condense the moisture out of the warm, relatively muggy southeasterly winds.  Hence, a bank of low clouds forms.  The southeasterly winds then push that batch of clouds onshore and there you have it: sea fog and rough morning commutes across the Central Gulf states this week.

Pretty “Cool” Ice Photos & Its “Effect” On Lake-Effect Snow

posted on Sunday, February 13th, 2011 at 8:19 pm

Think this winter’s been bad in the South?  Well imagine over 100 inches of snow… every year!  Places like the Great Lakes see it, routinely. You know when you hear about those Christmas or New Year’s reports of 35 inches of snow snarling holiday travel in places like Buffalo, New York?  Well, typically that’s caused by a phenomenon known as lake-effect snow.  Lake-effect snow is caused by an unstable atmosphere (similar to the atmosphere during a thunderstorm.)  In the case of thunderstorms, you have an atmosphere with lots of humidity, warm ground, and a cool upper atmosphere.  Lake-effect snow is caused by cold, arctic air rushing in on cold winds out of the northwest over the relatively warmer (and of course, moist) Great Lakes waters.  Now, of course, you need “water” to get lake-effect snow going.  If there’s ice covering the lake, the water vapor needed for lake-effect snow is not available and the lake basically “shuts down” for the production of lake-effect snow.

The Great Lakes, as you may  know, are very big: hundreds of miles long, tens of miles wide, and hundreds of feet deep, so it’s not likely they’ll all entirely freeze over for any significant amount of time, although it is, on rare occasion, possible that they’ll mostly freeze over, like during the very cold winters of 1976-1977, 1977-1978, and 1978-1979.  Most years, though, most locales on the lakes don’t get a break and get inundated with lake snow all winter long.

In several areas, though: far western New York, northwestern Pennsylvania, and northern Ohio, folks do get a break!  During the coldest months of the winter; it’s typical during many winters, the shallowest of all the lakes, Lake Erie, will nearly entirely freeze over and this nearly closes down the heavy snow machine along its shoreline.

February 8, 2011 Lake Erie Ice Cover, Image: NOAA

February 8, 2011 Lake Erie Ice Cover, Image: NOAA

In the latest February image of Lake Erie taken via satellite above, you can see  there’s lots of white over the lake.  That’s actually a sheet of ice.  The darker black area, in fact, is the area of the lake that has been left uncovered and unfrozen. By far, there’s more ice than water.   Therefore, it’s tough to get much more than lake-effect flurries going.  Earlier in the season, though, before it really gets cold, it’s a totally different story.

January 11, 2011 Lake Erie Ice Cover, Image: NOAA

January 11, 2011 Lake Erie Ice Cover, Image: NOAA

In the satellite photo above, you can see just a month ago, before the long duration of cold… the lake is wide open with plenty of water and water vapor to work with!  This is the season where we see the blizzards along the lake shore.

To check out the forecast in places affected by the lake  freeze-over lull, take a look at Cleveland and Buffalo.

On a side note, take a look at the imagery again and focus on the upper right.  That’s Lake Ontario.  It’s over 10 times deeper than Lake Erie.  You can see, between both photos, there’s not much change in the amount of white on the lake.  Lake Ontario, since its much deeper and contains a larger volume of water, has a much harder time cooling off and, therefore, has a much harder time freezing.  In places like Rochester and Watertown, New York, there’s nary a respite from the lake snow onslaught.

Arctic Air and New Snow Sets Stage For Record Lows

posted on Thursday, February 10th, 2011 at 8:17 pm
Snow Depth Analysis, Image: NOAA

Snow Depth Analysis, Image: NOAA

Texas, Oklahoma, Arkansas, Mississippi, Alabama and Georgia woke up to new fallen snow again this Thursday. Between the freshly fallen snow and arctic air mass, Oklahoma suffered from record cold temperatures.

Fresh snow has a high albedo, or high reflectivity. Generally speaking, objects with a high albedo reflect most of the sunlight that hits it. Surfaces with a high albedo include snow cover (especially fresh snow) and clouds. On the other hand, alsphalt and dirt tend to absorb heat… so the air above these surfaces would be warmer than the nearby snow covered area.

(This is why the snow on a highway will melt even when the nearby ground is covered in a blanket of snow.)

This high albedo of snow affects the air temperature. If the sun’s radiation is being reflected away from the earth, the air temperature will be lower in that area. The sun doesn’t directly heat the air. The sun’s radiation heats the earth, and the earth in turn heats the surrounding air. Sure, a little bit of the sun’s rays will heat the atmosphere, but most of the daytime heating comes from the longwave radiation coming from the surface of the earth.

Morning Lows, Oklahoma, Image: NWS Norman, OK

Morning Lows, Oklahoma, Image: NWS Norman, OK

Record lows were recorded in Oklahoma today because of the fresh snow and arctic air.

Dawn Brown, FOX 8 New Orleans

Paralyzing Winter Storms Rank 3 Out of 5

posted on Tuesday, February 8th, 2011 at 10:21 pm
2011 Northeast Storm, Image: NASA

2011 Northeast Storm, Image: NASA

NASA captured this image of the Christmas Blizzard of 2010 on December 28, 2010. (The clouds in the picture have waves, the snow looks like spray paint.) All in all, the system dumped almost 2 feet of snow across metro New York. The storm paralyzed the city, caused thousands of airline cancellations, and led to loud outcries from New Yorkers frustrated with the slow response. And some people just went a little crazy… did you hear the story about the guy who skied behind a car going 40 mph? Here’s the video from youtube if you missed it.

The National Climate Data Center finally came out with its ranking of the storm. There are currently 43 storms ranked on the Northeast Snowfall Impact Scale, the scale ranks storm from 1960 forward. The Christmas Blizzard or “Great Snowstorm of 2010” ranks as #20. (The two storms that followed on January 9-13th and February 1-3rd rank #18 and #19.)

Christmas 2010 Blizzard

Christmas 2010 Blizzard

January 2011 Snowstorm

January 2011 Snowstorm

February 2011 Snowstorm

February 2011 Snowstorm

In 2006, NCDC began ranking Northeast snowstorms based on their impact to the community. The storm is either notable (category 1), significant (2), major (3), crippling (4), or extreme (5). The storm is categorized by the amount of snow, the size of the area impacted and the population of the area impacted. A snowstorm that dumped 30+ inches of snow across portions of the Northeast in 1993 ranks the highest.

The difference between the Northeast Snowfall Impact Scale and the Saffir-Simpson Hurricane Wind Scale (a scale used in forecasting hurricanes), is that the snowstorm ranking is given after the storm hits. It’s not used to forecast the impact of the storm.

The difficulties in trying to forecast the impact abound. Just like determining the track of a hurricane, forecasting the track of a blizzard can be equally frustrating. The entire forecast can depend on the position and strength of the low pressure system in the center of the storm. (Hurricanes are tropical cyclones, blizzards or winter storms are extra-tropical cyclones. Both are centers of low pressure with a counter-clockwise spin. Hurricanes are warm-core systems, winter storms are cold-core systems.) In a winter storm, if the storm weakens or strengthens, or the center of the storm tracks 50 miles north or south, the amount of snow across the metropolitan New York region could range from 1-2 inches to 1-2 feet! In a hurricane, the strength of the low can be the difference between power outages and the widespread devastation.

Currently, forecasters try and determine the impact of a storm by the amount of snowfall and emergency managers response to the storm.  The Northeast Snowfall Impact Scale could eventually be used to forecast the storm in a manner similar to how the Saffir-Simpson Scale is used for hurricanes. It could eventually be used to give emergency managers an idea of how to prepare, how many snow plows and drivers to have on standby, how much water and/or milk you need to buy before you hunker down for the storm.

The south is preparing for yet another wintry mess. Catch the local forecasts in Little Rock, Jackson and Atlanta.

-Dawn Brown, FOX 8 New Orleans

NOAA Blames La Nina for Blizzard, Yasi

posted on Thursday, February 3rd, 2011 at 1:09 pm

When NOAA meteorologists posted their winter outlook, the weather phenomenon La Nina, was the driving force behind their forecast.

NOAA Winter Outlook, courtesy: NOAA

Winter Temperature Outlook, courtesy: NOAA

Winter Precipitation Outlook, courtesy: NOAA

Winter Precipitation Outlook, courtesy: NOAA

One month into the winter, when the West Coast was getting slammed with winter storms typical of an EL Nino year, and the southern states were suffering another round of arctic cold, NOAA proclaimed one of the strongest La Nina’s ever in the last century, the proof being the unusual rainfall over Australia and the cold sea surface temperatures in the Pacific Ocean.

Latest La Nina Analysis, courtesy: NOAA

Latest La Nina Analysis, courtesy: NOAA

When you look at the satellite analysis of sea surface temperatures in the central and eastern Pacific Ocean, you definitely won’t dispute the cooler sea surface temperatures. It definitely looks opposite the El Nino pattern, where warmer water builds up in the eastern equatorial Pacific, off the coast of Central and South America.

El Nino Comparisons, 1997 and 2004, courtesy: NASA

El Nino Comparisons, 1997 and 2004, courtesy: NASA

But, what about the impacts to the US? The West Coast was pummeled with storm after storm in early winter, raking up rain and snowfall totals normally seen during El Nino years. And while arctic outbreaks are common for the northern tier of the United States during a La Nina year, the southern states usually experience warmer winters during La Nina.

One phenomenon repeating itself this year is the Negative Arctic Oscillation. During a NAO phase, cold arctic air spills southward into the mid-latitudes or deep into the United States.

NWS Watches and Warning

NWS Watches and Warnings

The image above shows the weather warnings across the United States. The areas in pink indicate winter storm warnings for most of southeastern Texas, Louisiana and Mississippi. The NAO looks to be active again this week.

-Dawn Brown, FOX 8, New Orleans

Gulf Low Brings Another Winter Blast

posted on Wednesday, February 2nd, 2011 at 5:38 pm
February 2011 Blizzard

February 2011 Blizzard, courtesy: NASA

Click on the image above twice for a high resolution picture.

Calling it one of the largest storms since the 1950s, NASA turned its cameras toward the Midwestern States Tuesday to capture a winter storm stretching across 30 states. Chicago and Oklahoma City were two of the hardest hit cities. Chicago came to a standstill with its 3rd highest snowfall on record, 20. 2″ of snow fell during the blizzard. Blizzard warnings are issued when winds are expected to reach 35 miles per hour. That is one of the reasons this storm was so dangerous. The other reason was ice on the roadways. Warmer air in the upper atmosphere can support other types of wintry precipitation, such as sleet or freezing rain. Freezing rain is rain that freezes on contact with the surface or roadways.

If you want more information on sleet versus freezing rain, read my previous blog entry on wintry precipitation.

A lot of excitement here in New Orleans, Louisiana, as sleet began falling shortly before noon in our viewing area. The mighty Midwest storm yesterday was a rain and wind event for us, with a line of heavy thunderstorms crossing  before the arctic cold front blasted us with freezing temperatures overnight.

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