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May 11, 2012

Solar Pillar and Contrails . .  . Oh My!

Western North Carolina has been enjoying some beautiful weather since the rain moved out on Wednesday.  Those mostly clear skies set the stage for a beautiful sunset on Thursday evening (5/10) – with some atmospheric optics to boot!

The image above was shot about 4 minutes after the sun dipped below the mountain last night.  The high, thin, wispy clouds painted gold by the setting sun are called cirrus clouds and are made of ice crystals (as opposed to liquid droplets that makes up most other clouds, including the darker clouds to the right). Also visible are at least 10 contrails (short for condensation trails) produced by condensation of water vapor in the exhaust of aircraft jet engines.

The six-sided, plate-like ice crystals that form the cirrus clouds can create some very interesting optical phenomena, depending on how they are aligned within the clouds. In this case – the crystals are aligned horizontally, so that the light from the sun reflects off of the bottom side of the crystal, creating a vertical solar pillar. When the crystals are alligned vertically – we can see sun dogs (see the October 27, 2011 account by scrolling down).

Weatherlore says that the appearance of solar pillars, sundogs, and halos may herald the coming of stormy weather in a few days.  In this case – it’s true. We’ll likely see more cirrus clouds this evening and tomorrow, ahead of the storm system that is expected to bring rain into the region over the weekend. So – keep you eyes on the sky and perhaps you’ll see some interesting sites tonight around sunset.

May 3, 2012

The Greening of the Mountains

One of the most amazing transformations in nature is on display right here in Western North Carolina as trees and vegetation come alive in the spring. This process occurs over a period of time with the lower elevations “greening up” first. The flush of color then moves up the mountains where the highest elevations are the last to fill out, thanks to generally lower temperatures at the higher elevations.

While it has been green in the valley for quite a while, the trees at the higher elevations (4000 ft and above) are still in the process of waking up from winter. This transformation is visible thanks to NASA’s Aqua Satellite, part of the Earth Observing System that allows us to monitor the Earth.

The image below was taken on March 1, 2012 – a beautifully clear day that allowed a clear view of the brown, pre-spring landscape.

Image Credit: NASA and the  Space Science and Engineering Center (SSEC) at the University of Wisconsin-Madison.

By last week (April 28th)– the landscape had transformed into a lush green spring paradise seen in the image below, with the exception of the higher elevations which still appear dark brown.

Image Credit: NASA and the  Space Science and Engineering Center (SSEC) at the University of Wisconsin-Madison.

The forests of Western North Carolina play an important role in our local climate and even our daily weather conditions.  The green vegetation helps to hold moisture in the soil by shading the forest floor. But the plants also transpire significant amount of water vapor into the atmosphere, making muggy air and the puffy cumulus clouds seen in the picture above an almost daily occurrence. This added moisture also helps to aid in the formation of the afternoon thunderstorms that we see in the mountains during the warm months.

April 24, 2012

April Snow!

The Black Mountains didn’t live up to their name on Monday afternoon, blanketed with about 2” of snow.

While snow in April is not unheard of in Western North Carolina – this past weekend’s snow event seemed out of place, partly because we had such a warm March this year.  Many folks reported seeing snowflakes in and around Asheville on Sunday, but it was the higher elevations where there was enough snow to accumulate, turning spring back into winter – at least temporarily.

The map below shows where most of the snowfall accumulation took place across the region. Areas in white received at least a dusting of snowand the darker blue colors indicate where the heaviest snowfall occurred.

 

April 19, 2012

Spring rains . . . and there’s more on the way!

Map: NOAA’s National Weather Service

Showers and thunderstorms brought some needed rain to Western North Carolina this week – but, as usual, it was all about . . . LOCATION, LOCATION, LOCATION.

The official reporting location for Asheville’s weather is at the AVL airport, south of town, where they recorded a total of 2.16” of rain over the 2 day event.  You’ll notice on the image above that the recorded value corresponds well with the darker green pixels on the map indicating that between 2.0 and 2.5” of rain fell.  You’ll also notice that a good portion of Buncombe County received between 2.5” to 4” of rain, as indicated by the shades of yellow. 

This helps to illustrate that what is recorded at the airport (or any single point) is often not representative of the entire area. Even with the recent rain, AVL is still reporting 1.17” below normal rainfall for the year.

This is a common issue with in situ measurements (Latin, meaning “in place’) and is a good example of why weather radar and other forms of remote sensing (like satellites) are so important to providing a more complete view of weather and climate information. The image above was generated using the National Weather Service’s radar and rain gauge data combined to provide a more accurate picture. You can visit the website here.

So how does the region look for rainfall so far this year?

The image below shows the percent of normal precipitation since January 1 of this year, and indeed, most of the state is dryer than normal as the orange and yellow indicate below normal precipitation. Those of us in the mountains are faring better with year-to-date rainfall closer to what we would normally expect, and even a few locations with above normal levels as shown in green.

Map: NOAA’s National Weather Service

A scattered shower or thunderstorm is possible today and tomorrow – but there is a much better chance for more significant rain over this coming weekend. So, perhaps we’ll reduce the deficit at the airport.

April 4, 2012

Spring Storms Create a Foggy Morning

Spring brings the return of afternoon thunderstorms, but the impact of the rain can last long after the storms move on.

Yesterday’s thunderstorms left the mountains moist as the sun set, producing the blue ridges that this part of the world is so famous for.

However, the wet ground set us up for some thick fog this morning as the moisture condensed into fog across the French Broad River Valley. With clear skies overhead, it didn’t take long for the sun to heat the air enough to burn off the fog. You can see the process in the short animated clip of this morning’s visible satellite images below.

Satellite Images: NASA MSFC Earth Science Office GOES-E CONUS Visible Satellite Data

As you watch the clip, pay attention to the motion of the clouds near the North Carolina and Tennessee state line, north and west of Asheville.  These developing cumulus clouds are the first indication of the thunderstorms that are beginning to develop again this afternoon.

While we’re talking about thunderstorms, here’s your warning. The storm system that produced the severe thunderstorms in Dallas and Northeast Texas yesterday will be moving into the Southeast U.S. tomorrow. This will increase the risk of severe weather over the Carolinas tomorrow. So, please stay weather alert.

March 29, 2012

A Few of My Favorite Things . . .

The evening sky holds many wonders – but few are as wondrous as getting to see some of the brightest objects in our sky all clustered together. Such was the case last night when the crescent moon was accompanied by the brightest planets in our sky along with the constellation Orion and the bright star Sirius.  An amazing site that you may be able to catch again this evening if you look to the west after the sun sets.

The crescent moon is growing in size each night, so it’s called a waxing crescent. (In the image above, the 30 second exposure time has caused the moon to appear a bit smeared, hiding its crescent shape.)   To the lower-right of the moon are the two brightest planets in our sky, Venus and Jupiter. Venus –is the brightest object in our sky, other than the moon and our own sun.  Jupiter, the next brightest, is the largest planet in our solar system and you can easily see several of its moons using a pair of binoculars.

My favorite constellation of all, Orion (sometimes called The Hunter) is easy to identify with its classic shape seen in the image above. Betelgeuse (think of the 80s movie Beetlejuice) is a red supergiant star and you can see its reddish-orange tint even with your naked eye.  The three stars that create Orion’s belt point you to the star called Sirius (Yes, I am serious). Sirius is an amazingly beautiful star that is actually a binary star system (two stars orbiting each other).  Sirius is the brightest star in our sky other than our own sun.  If you watch it you will notice that is flashes brilliantly through a variety of colors. This process, called scintillation, is visible with the naked eye as well as through binoculars.

So here’s hoping for good visibility tonight! I hope that you get the chance to get outside and see the beautiful site. As we get into the warmer months, reduced visibility from haze and late day thunderstorms will make such clear viewing of the night sky more difficult.

Enjoy!

March 21, 2012

Spring Has Sprung!

As we woke up this morning to the first full day of spring – many across the county are dealing with an early spring that seems to have gone haywire. From tornado outbreaks in early March, to torrential downpours in the South, and heat waves in the north – March has been one for the record books.  Including a long-lived ridge of high pressure over the Eastern U.S. that has brought numerous record high temperatures to the Eastern and Central U.S. and Canada.

Credit: NASA Earth Observatory image by Jesse Allen, using data from the Level 1 and Atmospheres Active Distribution System (LAADS).

The map above shows land surface temperature anomalies based on data from the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument on the Terra satellite – showing temperatures compared to the average of the same eight day period of March from 2000-2011.  Areas with warmer than average temperatures are shown in red; near-normal temperatures are white; and areas that were cooler than the 2000-2011 base period are blue.

It’s no surprise that Western North Carolina is shown as above normal during this time period as our high temperatures so far this month have been well above average. Only four of the last 20 days in Asheville have been below average for the recorded high temperature! But – it’s hard to find anyone around here complaining about the weather. Our memories of the winters of 2009-2010 and 2010-2011 are still too vivid!

More information on the map can be found here: http://earthobservatory.nasa.gov/IOTD/view.php?id=77465&src=eoa-iotd

March 15, 2012

Return of the Scattered Thunderstorms

For many of us in the mountains – it seems that spring has sprung almost overnight as trees are flowering, birds are singing and allergies have hit full force (cough, cough). Another sure sign of spring. . . . scattered thunderstorms that pop up in the heat of the sun.

The storm pictured above popped up just after noon today close to where  Buncombe, Madison and Haywood Counties meet, west of Asheville . Not an large storm, but radar indicated that the storm did have a hail shaft within it at about 12:30 this afternoon.

These thunderstorms are very typical of spring and summer in the Southeast U.S.  The sun warms the land and the warm air rises in a column creating a cumulus cloud. Cumulus clouds are plentiful this time of year. The puffy white cottony clouds dot the sky on days when there is ample water vapor in the air. Under the right conditions, the moist air continues to rise, the clouds grow tall and a thunderstorm is born. In most cases, these type of storms are not very large and they don’t live for long, especially this early in the year. However, they can produce some locally heavy rain, hail, and lightning  - so they can be dangerous to those who find themselves underneath one. It’s all a sure sign of spring in the mountains.

The image below was taken by NASA’s Aqua satellite this afternoon at around 2:45 pm as it passed over Western North Carolina. You can see the small cottony cumulus clouds over our region as well as the larger, taller and more feathered tops of the thunderstorms that had developed during the early afternoon. Click on the link above for the full image – beautiful!

Sat Image Credit: NASA & Space Science Engineering Center at University of Wisconsin-Madison

Want to know more?  The Institute is hosting a free severe weather workshop at A-B Tech’s Asheville campus on Saturday June 2 with the National Weather Service office in Greenville/Spartanburg.  Mark your calendars!! More details to come.

February 29, 2012

The Word of the Season is  . . . Variability

As we say goodbye to February (YEAH!) and hello to the coming spring – you’ll notice how changes to our environment seem to happen very quickly this time of year.

The sun is growing higher in our sky every day as we head toward the official start of spring on March 20th. Take a look at the image I shot at sunrise on Tuesday morning of this week (2/28). You’re looking due east at the Black Mountains and you can see where the sunrise is occurring now on the horizon compared to where the sunrise occurred at the time of the winter solstice in December.

As we head toward spring, the sun is heating up the Northern Hemisphere again and bringing life back to the mountains. Clear and sunny days can quickly turn cloudy and stormy as North America becomes the battleground for competing warm and cold air masses. Such is the case now as a major storm is spreading snow across the northern states while bringing the chance for severe weather across the central and southeast U.S., including Western North Carolina later today.

So, while we’re beginning to enjoy the signs of the coming spring, remember that because the word of the season is variability – we often see some of the biggest winter storms during the months of March and April.   As they say . . . . “it ain’t over until the fat lady sings” and she’s still backstage, ready to go on at a moment’s notice!

If you’re interested in keeping an eye on the storms, I encourage you to bookmark this website.  It provides a great country-wide view of the Doppler radars that are so critical to providing severe weather information.

February 23, 2012

The Weather Seesaw Returns

Many of us woke up this morning to widespread fog across the French Broad River Valley, thanks to last night’s rain that caused the layer of air at ground-level to become saturated – producing a cloud on the ground – or fog. Looks like we may see similar conditions on Friday morning because we may see some more storms again tonight that may lead to some fog early tomorrow morning – especially in protected valleys.

Enjoying the great, mild weather today?  I encourage you to do so because winter will make itself known again tomorrow as a strong cold front will likely produce strong, gusty winds during the day as it brings some much colder air into Western North Carolina. The National Weather Service has already issued a Wind Advisory for our region starting at 9:00 a.m. tomorrow as a heads-up for the possibility of downed trees and difficulty in driving large vehicles.  Keep in mind that fires can easily get out of hand in high winds, too. So, no burning tomorrow.

Typical of the systems that we’ve seen this winter, we’ll probably see some short-lived rain and maybe a few snow flurries with the cold front, all helping to keep the western part of the state in much better shape than central and eastern sections who continue to see below average rainfall. 

Interested in seeing how we’re faring compared to the rest of the state? The State Climate Office of NC has just released its annual climate summary containing an overview of the extreme weather observed across North Carolina in 2011, including information on the April 16th tornado outbreak, the summer heat and drought, and Hurricane Irene's landfall in late August. All this and more is online here.

February 16, 2012

Where is Winter?

Snowflakes were flying earlier this week, as Valentine’s Day started off white at the higher elevations.  This image of Max Patch in western Madison County shows the short-lived snow.  So – what has happened to this winter? Why has it been so different than the last two years?

Following the harsh winters that Western North Carolina endured during the last two years, we were all waiting with some dread to see how the winter of 2011-2012 would present itself.  I don’t know about you, but I’ve really enjoyed the ability to work in the yard this winter - the same yard that was covered in 3 feet of snow during the same period for the last two years!

Whether you’re enjoying the break – or are wishing for a good ol’ winter storm – we can all look to the polar vortex for hints about what has contributed to the warmer than usual winter across much of the lower 48 states. The polar vortex is a band of winds that blow counterclockwise, circling the Arctic.  During some years, that band of winds is very strong and acts as a dam that keeps much of the cold air locked up over the polar regions, and out of the lower 48. So far, that’s been the situation for much of this winter.

Meteorologists track the polar vortex by watching two related oscillations in the Northern Hemisphere, the North Atlantic Oscillation (NAO) and the Arctic Oscillation (AO). Similar in some ways to El Nino and La Nina, these regular oscillations impact short-term climate, but their influence is usually limited to the Northern Hemisphere. If you are interested in learning more about these oscillations and their impact on North Carolina, the State Climate Office of North Carolina has an excellent write-up here.

For much of this winter, the NAO and AO indices have both been very “positive”.  In this state, the polar vortex has kept much of the cold air locked up over the arctic region resulting in less snow and fewer outbreaks of really cold air across the contiguous U.S.  The image below shows the NAO and AO indices for the month of December for each of the last sixty years. You’ll notice that December of 2011 was strongly positive for both the NAO and the AO, but that the previous 2 winters were very strongly negative for both of the indices.  Do you remember a particularly bad winter over the last 60 years? Take a look and see is both the NAO and the AO were both negative. The winters of much of the 1960s are a good example.

Graph by Hunter Allen (NOAA) and Robert Simmon (NASA) based on data from NOAA’s National Weather Service Climate Prediction Center.

Keep in mind – we have a long way to go until spring, and some our most impressive winter storms can still occur even into April.

In the meantime, Western North Carolina continues to enjoy above average temperatures and precipitation.  However,  it looks like we may see a little snow, especially in the mountains this weekend. Not too bad - for the dead of winter.

 

February 1, 2012

W is for Water . . . not Winter (apparently)

As we head into February, Western North Carolina continues to see plentiful rain as a steady stream of weather systems spread rainfall across the southern plains and into our area. 

The image below shows the rainfall totals for January across the SE U.S. (The scale on the right is in inches.)

Asheville has seen its fair share of rain over the last several months.  The monthly total for January at the AVL airport was 3.85”.  That’s 0.18” above the average rainfall for January. And, we came into 2012 with some above average rainfall accumulations in November (1.67” above average) and December (1.52” above average).

With rain in the forecast for much of the weekend, it looks like we’ll keep adding to the totals in the near-term. 

These images were generated using the National Weather Service’s radar and rain gauge data here.

January 26, 2012

Our Planet – A Unique View of a Truly Unique Place!

Most of us have seen the famous “Blue Marble” picture that was taken on December 7, 1972 by the astronauts on Apollo 17 as they were headed to the moon.  The famous image, below, was taken with a hand-held camera just over 5 hours after launch, as the last manned lunar mission was about 2800 miles from the Earth.

Credit: NASA

NASA has now released an amazing new view of our planet. One that highlights the advances that we’ve made in observing the Earth’s weather and climate from the satellites that orbit our planet.

Credit: NASA

Click on the image above for a high-res version (16.4 MB)

The image above is not a single image taken with a camera, but a series of images taken 512 miles above the planet by the newest Earth-observing satellite launched by NASA, the Suomi National Polar-orbiting Partnership (NPP).

Launched from Vandenberg Air Force Base in California on October 28, 2011, the satellite began making its first measurements in November as scientists tested the instruments. The image above was produced on January 4th of this year (an amazingly clear winter day across North America) by the Visible Infrared Imaging Radiometer Suite (VIIRS), one of the 5 scientific instruments on board.You may remember that on that day Western North Carolina had just seen snow at the higher elevations. You can see the cloud cover with that system moving toward the NE U.S.in the image above. (See the January 5th Fun Facts e-mail for a view of the snow from NASA’s Terra satellite.)

As a polar-orbiting satellite, Suomi NPP rises in the south and sets in the north on the daylight side of the planet. As the Earth rotates below it, the satellite circles from south to north 512 miles overhead imaging a 1,900 mile wide swath. This allows the satellite to cover the surface of the globe in a day. But the satellite’s orbit is also sun-synchronous, meaning that it passes over the equator at the same local time on the ground. This maintains the angle between the sun and the Earth – so all images have similar lighting producing a consistent and well lit view across the whole globe.

Suomi NPP does so much more than take beautiful images. It is the first satellite designed to collect data to improve short-term weather forecasts and to increase our understanding of long-term climate by measuring key climate variables.  It is a bridge between NASA’s Earth Observing System satellites and the next generation of weather and climate observing satellites called the Joint Polar Satellite System, a National Oceanic and Atmospheric Administration (NOAA) program.  Data from Suomi NPP will come to NOAA’s National Climatic Data Center in Asheville.

To learn more about Suomi NPP click here.

To learn more about how NASA constructs images of the Earth - click here.

 

January 19, 2012

Where the Trees Are . . . and Aren't

Credit: NASA Earth Observatory map by Robert Simmon, based on multiple data sets compiled and analyzed by the Woods Hole Research Center

For the first time ever, researchers now have a detailed view of the forests across the lower 48 states. Taking 6 years to complete, the National Biomass and Carbon Dataset project mapped our nation’s forests at the highest resolution ever (30 meters), providing baseline information about tree height, forest structure and carbon storage capability in the year 2000.

It’s believed that as much as 45 percent of the carbon stored on land is tied up in trees. Western North Carolina’s unique climate has produced amazing biodiversity across our region and our important role in the Earth’s carbon cycle is evident in the dark green colors on the national map above. The map depicts the concentration of biomass— a measure of the amount of organic carbon—stored in the trunks, limbs, and leaves of trees. The darkest greens reveal the areas with the densest, tallest, and most robust forest growth.  

And while it’s interesting to see the important role that our forests play in the role of carbon storage - it’s the details of the new maps that will leave you stunned.

The image below is an up-close look at Western North Carolina/Eastern Tennessee taken from the national map. Heavily forested areas are dark green, lakes are light blue, and areas with less trees are lighter in color.  Can you make out the major population centers in the region?  If you look carefully – you can even see the corridors formed by major roadways such as I-40 through Buncombe County and Highway 19 through Madison and Yancey Counties.

Credit: NASA Earth Observatory map by Robert Simmon, based on multiple data sets compiled and analyzed by the Woods Hole Research Center

I’ve labeled some of the major points of interest in the image below to help you find your way around.

Credit: NASA Earth Observatory map by Robert Simmon, based on multiple data sets compiled and analyzed by the Woods Hole Research Center with annotation by Pamela McCown

You can find NASA’s story on the project here.

January 11, 2012

Angry Skies

The clouds thickened over Western North Carolina this morning (Wed. 1/11) as the latests storm system brought rain into the region. The image above was taken in Madison County as the rain was moving in. We’ll continue to see showers, and maybe even a few isolated thunderstorms, through the rest of the day and into tonight.   The next weather maker is right on its heels and we’ll feel its impact by late tomorrow.

A heads-up as the mild temperatures we’ve been enjoying this week will come to an end late tomorrow as a cold front sweeps into the region. The cold air will help produce snow showers across the area, with accumulations most likely in the higher elevations tomorrow night.

The cold front will also bring gusty winds that could increase the risk of falling trees, especially with our soils so wet from today’s rain.

Wet soils also increase the risk of ice on roadways tomorrow night and into Friday as the runoff and temperatures below freezing will combine to create problems with black ice on roads. So, be careful.

NASA’s Terra satellite caught the 2 weather systems as the satellite passed over the Central and SE U.S. at around noon today. You can see the area of low pressure that I labeled as “1” and its movement to the NE.  The cold air (labeled “2”) is moving toward the SE and is expected to arrive in Western North Carolina late in the day tomorrow.

Image Credit: NASA and the  Space Science and Engineering Center (SSEC) at the University of Wisconsin-Madison.

You can always find the latest forecasts and radar images for Western North Carolina from the National Weather Service Forecast office in Greenville-Spartanburg.

January 5, 2012

Clear Skies for This Evening’s International Space Station Pass

Sat Image Credit: NASA & Space Science Engineering Center at University of Wisconsin-Madison

The image above was taken today (1/5/2012) by the Terra satellite, part of NASA’s Earth Observing System. It shows that the skies are so clear over Western North Carolina that we can still see the areas of snow left from the snow event earlier this week.

These clear skies should make for excellent viewing this evening of the International Space Station as it makes a pass over our region beginning at 6:33 pm.  Look to the WNW. You’re looking for a bright light, similar to Venus, that is visibly moving toward the south.  Traveling at a speed of over 17,000 mph, the ISS will be visible for over 6 minutes as it crosses relatively low on the horizon – at about 30°.

Grab a pair of binoculars, if you’ve got them, and watch this engineering marvel as it orbits the Earth at an altitude of over 230 miles.

You’ll find more information about spotting the International Space Station here.

 

December 21, 2011

Bring On The Light!

Are you tired of the long hours of darkness?  If so – rejoice as the powers of light are about to overcome . . . the dark side (insert “Darth Vader’s Theme” music here)!

The December (winter) solstice occurs at 12:30 AM EST tomorrow morning marking the beginning of astronomical winter in the northern hemisphere, and the return of more hours of daylight.

For many of us – the winter solstice passes almost unnoticed thanks to modern conveniences like electricity and cars with headlights. But these are relatively new technologies that allow us to function through the long hours of darkness that occur this time of the year. Past generations were much more aware of the changing seasons because the lack of natural light had a significant impact on one’s ability to be productive. As a result, the winter solstice was a time of great celebration.

Beginning tomorrow– we will gain precious daylight each day as the Earth’s northern hemisphere begins to pick up more sunlight on our yearly trek around the sun. These changes occur because our planet is tilted 23.5 ° in relation to the sun. And, at the winter solstice in the northern hemisphere, the Earth’s axis is tilted at its largest angle away from the sun as shown in the illustration below. 

Credit: Timeanddate.com                              Note: Not to scale

Today and tomorrow (12/21 and 12/22) are the days with the shortest daylight hours of 2011 here in Western North Carolina. Each day having just under 9 hours and 45 minutes of daylight in Asheville. Compare that to the 14 hours and 34 minutes of daylight that Asheville sees at the summer solstice in June, and you can understand why our ancestors would celebrate the return of the sun in late December with festivals that would last for days, even weeks.

I encourage you to take time over the next couple of days to notice where the sunrise and sunset occurs on the horizon.  This is as far south as the sun will appear to us  - and the difference between where the sun rises and sets in December, and where it rises and sets well to the north in June, is truly amazing.

Click on the image below to get an interesting perspective on how the sun’s light changes on the Earth through the year.  This movie was produced from a series of images from the European Organization for the Exploitation of Meteorological Satellites (EUMETSAT).

Credit: NASA images and animation using data ©2010 EUMETSAT

December 13, 2011

Meteor Shower Tonight!

Mid-December brings one of the most unique meteor showers that we get to see throughout the year, the Geminid Meteor Shower. And, although viewing conditions won’t be perfect for viewing in Western North Carolina, the mild conditions may make it worth the effort.

We’ll likely see some cloud cover with the bright Waning Gibbous moon tonight (just past full at 90.5%). We may also see the development of some fog in the valleys overnight, but if you venture outside after 10:00 tonight, set out a blanket, make yourself comfortable and give your eyes time to adjust to the darkness, you may get a glimpse of a few meteors. Point your feet toward the East, and look toward the constellation Gemini (see the sky map below). Viewing is always best if you can get to an area without city lights, but we’re expecting mostly cloudy skies tonight. So, a special trip away from any lights may not be worth the effort if the clouds do set in.

Most meteor showers are produced as the Earth crosses the debris path left by a comet. However, the Geminid Shower is unique because it’s created from the dusty debris left by a near-Earth asteroid named 3200 Phaethon.

 Credit: Dr. Tony Phillips, NASA Science News

For more detailed information on the Geminid Meteor Shower from NASA Science News, click here.

 

December 8, 2011

Snow – From Two Different Perspectives

Last night’s snowfall blanketed the higher elevations with a couple inches of snow bringing beautiful views this morning, both on the ground, and from space!

The image above was taken by the GOES-13 satellite that hovers about 22,300 miles above the Earth to provide critical weather observations over the Eastern U.S.  Clear skies at sunrise made it possible to see the white areas of snow along the Southern Appalachian Mountains. If you look closely, you can also see the snow on the mountains of NE Buncombe County.  

The image below shows the ground truth. Beautiful snow – but also areas of rime icing on the trees.

Rime icing occurs when super-cooled (below freezing) water droplets collect and freeze on objects. This happens when low clouds and/or fog form in sub-freezing conditions and it occurs quite often during the cold months here in Western North Carolina. Up close, rime ice crystals are uniquely beautiful because they grow INTO the wind, making delicate spikes.

 

November 30, 2011

First Accumulating Snowfall of the Season. From this . . .

. . . to this in 3 hours.

Early yesterday afternoon (11/29), snow flurries started at the higher elevations in Madison County and it wasn’t long before a dusting turned into the first accumulating snowfall of the season.  The first image above was taken around 1:00 yesterday afternoon. Three hours later, the same trees resembled the flocked Christmas trees I remember seeing at the tree lots of my youth. (I grew up in Houston, TX - I had no idea what a real snow-covered tree looked like!)

There were still snow flurries in the mountains this morning. But by this afternoon, the snowfall has come to an end and the clouds are slowly dissipating to the north of Asheville as the cold air continues to spill into the valley through the gap formed by the French Broad River.

Unofficially, we saw between 2” and 2 ½ “ at 4000 ft.  If you’d like to see the reports from around the region, you can find the National Weather Service Spotter Reports here.

November 21, 2011

Doing the Wave . . .

You may have noticed a significant change in our skies yesterday afternoon as fair skies turned cloudy. These clouds moved in from the west late in the day ahead of the system that brought showers overnight and more significant rain into the region this afternoon.

I noticed an interesting feature to the clouds . . . waves. The waves are caused by the interaction of the air with the complex terrain in the mountains and they occur fairly regularly, especially in the fall, winter and early spring as storm systems approach from the west. The clouds in the picture are called Altostratus Undulates.

Meteorologists classify clouds using three main criteria:

-Height of the cloud base

-Shape

-Whether or not the cloud is producing precipitation

 In this case, the clouds were at mid-level (6,500 – 20,000 ft). So, they are given the name Alto –meaning mid. Their shape is like that of a sheet or blanket. So, they are called Stratus – meaning layer.  And, you can recognize the word undulate, meaning wavy. (Scientists love to use Latin to classify things – even clouds!)

 November 9, 2011

Planets at Sunset

It’s easy to forget that we live on a rock that is hurling through space in an orbit around our star – but occasionally, we can see reminders of that fact when our fellow planets are beautifully displayed in the sky over our mountains.

This is a great month for sky watchers. The planets are putting on a show in our evening skies and our atmosphere is typically clearer than it is during the summer months thanks to frequent frontal passages that help bring in cleaner and drier air.

The image above was taken last night (Tues 11/9/2011) as Venus and Mercury (along with a few cirrus clouds) were visible to the southwest after sunset. Clouds have increased today (Wed) ahead of an approaching cold front that will hamper viewing tonight, but clearer skies are expected later in the week, and it will be easy to spot Venus as the bright “star” on the southwest horizon after sunset.   Mercury is there too, to the lower left of Venus, but you may need to look through binoculars to really see it well.

Have you been wondering what that brilliant evening star in the East is?  It’s not a star at all, it’s Jupiter!

Looking to the East just after last night’s sunset, Jupiter was a bright beacon just below the moon.  The planet is easy to spot because it is so bright and it remains visible all night as it climbs high in our sky and eventually sets in the west in the early morning hours. Jupiter will be easy to see all month. So, pull out your binoculars or telescope and you’ll even be able to see some of Jupiter’s moons - well worth the effort!

October 27, 2011

Sundogs

Just before sunset last night – the ice crystals in the cirrus clouds that you can see in the picture created an optical phenomena known as a sundog.  Sundogs, also called parhelia (Greek, meaning “beside the sun”) appear to follow the sun as it moves in the sky -  that is why they are called sundogs.

A little background – cirrus clouds are high, thin, nearly transparent wispy clouds that are made of ice crystals.  Sundogs occur when the ice crystals that form the cirrus clouds are all aligned vertically so that they refract the sunlight and produce bright spots of light concentrated on either side of the sun.  In many cases there are two spots, one on each side of the sun. Last night, I was only able to see one sundog that appeared to the south of the sun about 15 minutes before sunset when I took the picture.

Weather lore sayings warn that sundogs can alert us to a coming change to the weather.  In this particular case, the weather lore will prove to be correct.  Last night’s cirrus clouds were the first sign of increasing moisture ahead of the clouds, rain and colder air that are moving into Western North Carolina tonight and tomorrow (Thursday and Friday, 10/27 & 10/28).

October 18, 2011

So soon to say goodbye . . . Brace yourself!

If you have a favorite color spot – make a point to see it today before winter-like conditions move into the area beginning tomorrow!

A cold front will move into Western North Carolina early tomorrow bringing much colder air, rain and gusty winds that will likely bring many of our fall colors crashing to the ground. Tomorrow (Wed) will seem dramatically different than the beautifully warm days we’ve enjoyed recently. So, be prepared.  Scattered showers and falling temperatures throughout the day will combine with gusty winds tomorrow night into Thursday and that’s not good news for those of us who enjoy the color of fall leaves.

There’s also a decent chance for snow for folks above 3500 ft. The Great Smoky Mountain National Park will likely see snow beginning during the day tomorrow and that area of snow will move toward the east into Haywood and Madison Counties by sunset tomorrow with accumulation possible through Thursday, especially at locations over 4000 ft.

So, enjoy these last hours of beautiful fall weather and be prepared for a taste of winter . . .  all too soon if you ask me!

 October 12, 2011

Foggy Start to a Beautiful Day!

This morning started with fog over many of the valleys in Western North Carolina, as you can see in the image above of Mount Pisgah taken across the layer of fog that settled into the French Broad River Valley overnight.

With mostly clear skies over the region, the morning fog shows up well on visible satellite images.  Click the image below for a loop of images taken by the

Geostationary Operational Environmental Satellite-East (GOES-E).  Note the arrow pointing to Buncombe County in the first frame of the animation to help you get your bearings. You can see the fog disappear as the morning progresses.

As a geostationary satellite, GOES-E travels at the same speed as  the Earth’s rotation, allowing it to hover over the same place on the planet at an altitude of about 22,300 miles above the Earth. The U.S. normally operates two meteorological satellites in geostationary orbit, GOES-E and GOES-W. These satellites provide many of the images that we use to track weather systems, including the satellite images you see during weathercasts on the local news.

For more information on the GOES satellites, click here. Interested in more satellite images? You’ll find one of my favorite resources here.

 

October 6, 2011

Smoke on the Water . . .

Well, OK – it’s really fog - but I could still hear the Deep Purple song in my head this morning as the French Broad River is clearly visible snaking through the valley under its thin veil of fog just before sunrise this morning.

Light winds, clear skies and longer nights are the perfect recipe for the development of river fog. The relatively warm water of the river gives up some of its moisture to the cool air just above the river and the air becomes saturated, creating a layer of fog. Fog develops when the air temperature drops to the dew point and the water vapor in the air condenses into water droplets.  Once the sun rises, the air quickly heats up (so it’s no longer saturated) and the fog vanishes.

For those of you waiting for the rest of the phrase . . .

 . . . And Fire in the Sky

Turning to the east just seconds later - about 60 seconds before the sun rose over the Black Mountains.

 

September 29, 2011

Too Cool to Not Share!!

The astronauts on the International Space Station (ISS) captured an amazing movie of the “southern lights” while passing over the Indian Ocean on September 17th.  Click on the image above to start the movie.You can see the solar panels and other sections of the ISS in the movie as the station passes over the Southern Hemisphere.

 The “southern lights” (aurora australis) are the South Pole’s version of the aurora borealis, the “northern lights”. This display was brought on by an explosion of hot, ionized gas from the Sun—a coronal mass ejection—that left the Sun on September 14, 2011.

The beautiful ribbons of light are caused by fast-moving electrons that collide with Earth’s upper atmosphere, transferring their energy to oxygen and nitrogen molecules and making them chemically “excited.” As the gases return to their normal state, they emit photons, small bursts of energy in the form of light. The color of light reflects the type of molecules releasing it; oxygen molecules and atoms tend to glow green, white or red, while nitrogen tends to be blue or purple. These lights originate at altitudes of 60 to 250 miles in our atmosphere

For more information – visit NASA’s Earth Observatory website here.

September 22, 2011 

The Season of Spectacular Change!

At 5:05 a.m. (EDT) Friday morning, those of us in the Northern Hemisphere pass into what is arguably the most wondrous of all seasons . . . autumn.

We’ve already seen a shift to cooler conditions as the Sun is no longer at its highest point in our sky and you may have noticed how the hours of daylight are getting shorter as well. At noon on June 21st, the longest day of this year, the Sun was at its highest elevation angle above Asheville at 77.9° and we enjoyed 14 hours and 34 minutes of daylight. By September 23rd, the Sun’s angle at noon has already decreased to 54.3° and the daylight hours have decreased to 12 hours and 7 minutes.

Changes happen quickly this time of the year.  The leaves seem to change overnight and the squirrels are so busy that they forget to look both ways as they cross the road and many of them meet their fate.

Enjoy these days as they too will pass quickly. Our orbit around the sun will soon bring the shortest days in the Northern Hemisphere when we will have only 9 hours and 45 minutes of daylight on the first day of winter in December.

 For more information:  http://www.timeanddate.com/worldclock/astronomy.html?n=745

September 15, 2011

Looking Into the Face of Evil

If you suffer from allergies, late summer is a particularly bad time because it’s when the ragweed plants in our area release their pollen . . .and spread misery.  There are numerous species of ragweed, some are short, but the Giant Ragweed plant I took this picture of yesterday in Madison County is over 13’ tall! In all, there are 21 species of ragweed in the U.S. A single plant lives only one season, but can produce up to 1 billion grains of pollen.

The individual grains of pollen (shown magnified in the inset picture) travel long distances on the wind, thanks to tiny air bladders that help them to be buoyant.(You can see the bladder as the light circle on the outer edge of some of the grains.)

Weather plays an important role in pollen production and dispersion.  The plants typically release the pollen in the early morning, just after sunrise when the relative humidity is fairly high. The moisture helps the air bladder remain flexible so the grains can catch the breeze and travel long distances. Ragweed pollen has been measured in the air 400 miles out to sea and 2 miles up in the atmosphere!  Rain and temperatures below 50°F help to slow the release and rain also helps to scour some of the pollen from the air as it falls. So, those of us suffering may get some temporary relief with the approaching cold front.

Additional Info:

Avoid Nasal Allergies.com http://www.avoid-nasal-allergies.com/index.html

Asthma and Allergy Foundation of America http://www.aafa.org/display.cfm?id=9&sub=19&cont=267

September 7, 2011

How Much Rain Did You Get?

The image above shows the wide variation of rainfall that occurred across the region over the Labor Day weekend as a result of the remnants of Tropical Storm Lee. While it may look like someone spilled something on the map, the legend on the right side of the image (units are in inches) will help to make sense of the colors.  Just like the radar images you see on the evening news, the brighter oranges and reds indicate the heavier rainfall,as seen just south of Boone where there were reports of 6”- 8” of rain.   The total for the event in Asheville, recorded at the airport, was 1.82” of rain.

The image below shows the impact of the rain to date over the Eastern U.S. – where it continues to rain, even into today (Wed 9/7/2011).

 

These images were generated using the National Weather Service’s radar and rain gauge data here.

August 31, 2011

The Layer We Live In

The Earth’s atmosphere has many layers, each playing their part to make this planet an oasis for life. You’ve heard of the Ozone Layer – located in the stratosphere – it helps to absorb dangerous ultraviolet radiation from the Sun. The troposphere is the lowest layer of atmosphere and is where almost all weather occurs.  The lowest part of the troposphere - where we live  - is called the  Planetary Boundary Layer or PBL.  This layer, usually less than 1 mile deep is where our atmosphere is in contact with the planet. When conditions are right, you can see the PBL from higher elevations, as was the case yesterday evening (8/30/2011). The recent stable weather pattern over Western North Carolina has not allowed the air in the PBL to mix with the free atmosphere above it.  As a result, tiny particles of smoke, pollen, dust, etc. have collected in the PBL causing the hazy conditions that we sometimes experience during the summer. In the image taken yesterday evening, the PBL is plainly visible hanging over the valley. Good news is that we are expecting a change to the weather pattern during the upcoming holiday weekend that may bring a chance of rain and help to clear the particulates from the air.   

August 24, 2011

Irene Is Cause for Concern as Major Hurricane Takes Aim on NC and the Highly Populated East Coast

Many of us in Western North Carolina know that hurricanes are not something to dismiss simply because we’re in the mountains and hundreds of miles from the coast.  The storms of 2004 (Charley, Frances, Ivan) left their mark on the mountains and our communities with flooding rains, landslides, and high winds.  On its current projected path, Hurricane Irene does not pose an immediate threat to the mountains - we may see gusty winds and a shield of high clouds from the storm. However, it does pose a threat to much of the state and will threaten millions as is moves up the coast into the Mid-Atlantic and New England. Those with property and/or family along the coast should stay informed and have plans for contacting those in the path if the worst should be realized. Irene reached Category 3 status this morning and may become a Category 4 hurricane on Thursday.

 Important points to remember:

• Do not focus only on the path of the storm and its projected landfall.  Irene is a large storm and it will have a significant impact over a very large area.
• If you own property along the coast, do NOT plan on “riding out the storm” along the coast. All indications are that this will be a historic hurricane with the potential to do really bad things to property, life, communication systems and the structure of the coast itself.
• Stay informed!  Here are my favorite sites for information related to tropical systems:

• National Hurricane Center :  http://www.nhc.noaa.gov/index.shtml#IRENE  (lots of maps so you can see what the experts think the storm will do)
• NASA: http://www.nasa.gov/mission_pages/hurricanes/archives/2011/h2011_Irene.html  (cool satellite images and visuals)

Image and video from NASA

 Click on the image to see a video of Irene as it grows from a disorganized system into a Cat 3 Hurricane with a well-defined eye. You may notice that you can see the change from day to night sweep westward across the land as the video progresses.

 

August 23, 2011

Morning Fog Along the French Broad River Valley

The cooler and drier air we’re enjoying across Western North Carolina on this late summer day set the stage for fog this morning across the region, especially along the rivers.  This image, taken at 7:08 AM on 08/23/2011 shows the fog in the French Broad River Valley as seen from Madison County looking south toward Asheville.

The French Broad is not only a focus of recreation for locals and tourists alike, it also impacts the weather and climate of the area by allowing air masses and storms to move from Tennessee into North Carolina through the valley formed by the river. 

Some say that the French Broad River is the third oldest river on Earth and it is one of a few rivers in the U.S. that flows to the north! (http://www.ashevillenc.com/area_info/french_broad_river )