David_Aldrich's Blog

Tonight: 30s and rising.

Cloudy, scattered rain showers or sprinkles.  Patchy ice possible in the Lehigh Valley and Poconos, but NOT likely.

Winds: SSW 5 - 10 mph.

Highs Monday: near 45 degrees

Damp start, Partly cloudy, Breezy.

Winds: WNW 10 - 15 mph, gusts to 25 mph..

TUESDAY:   P.M. Ice to Rain, Warm Late. Highs around 35 NORTH, 40 Philly Metro and 45 degrees SOUTH.

It will be warmer Tuesday night, than it will be during the day, as a warm front approaches from the South.

WEDNESDAY:  Rainy, Damp, Warmer.  High near 53 degrees.  Warmer South and east toward Millville and Atlantic City.  Low to mid 40s for the Lehigh Valley.

Okay, here is what I am thinking.  It is Sunday night.   And not much has changed, in my view.  Everyone in the weather community has still got themselves worked up about a storm that is still 2 days out, wondering just how many snow flakes am I going to get on Tuesday.  The answer ?  Not many.  Think SLEET and FREEZING RAIN, my friend.

Are you a snow lover ? So am I.  But as I said yesterday.  Give it up. This is NOT your storm, in my opinion.  I mean that.

I think the worst case scenario is growing more likely:

0.25 to 0.50 inches of SLEET (and some freezing rain) before changing over to plain heavy rain of another 1 inch plus.

Therefore, we have got roughly 1 to 1.5 inches of liquid to play with. I also tend to think the icing will be MORE of a problem, if it happens, NORTH of Willow Grove to Allentown.

The start time for this event appears to start late Tuesday afternoon into the evening hours.

Wednesday looks rainy and damp. I still like lower 50s for highs on Wednesday.

Thursday will be much colder.  Highs near 35 degrees.  Gusts of wind around 40 mph.  Flurries and snow showers are likely with a half inch or less for the entire viewing area.  With flurries and wind, someone is bound to cry "snow squall !"

Whatever suits your fancy.

David

Tonight: 18 to 25 degrees from suburb to city.

Starry skies, cold.

Winds: NW 5 - 10 mph.

Highs Sunday: 38 to 42 degrees from suburb to city

Sunny morning, Few afternoon clouds.

Winds: W to SW 5 - 10 mph.

MONDAY: Brief pre-dawn rain shower possible, otherwise, partly cloudy and breezy. Gusts 25 to 30 mph.

High around 45 degrees.

TUESDAY:   Ice to Rain, Warm Late. High around 45 degrees. It will be warmer Tuesday night, than it will be during the day, as a warm front approaches from the South.

Okay, here is what I am thinking. It is Saturday night. And everyone in the weather community has got themselves worked up about a storm that is still 3 days out.

Are you a snow lover ? Give it up. This is NOT your storm, in my opinion.

I think the worst case scenario is this:

0.25 to 0.50 inches of SLEET (and some freezing rain) before changing over to plain heavy rain of another 1 inch plus.

Therefore, we have got roughly 1 to 1.5 inches of liquid to play with. I also tend to think the icing will be MORE of a problem, if it happens, NORTH of Willow Grove to Allentown.

The start time for this event appears to start late Tuesday afternoon into the evening hours.

Wednesday looks rainy and damp. I still like lower 50s for highs on Wednesday before temperatures drop in the late morning.

David

Composition of the Atmosphere Near the Earth's Surface

Permanent Gases

Nitrogen  (N2)

78.08 percent

Oxygen  (O2)

20.95 percent

Argon  (Ar)

0.93 percent

Neon  (Ne)

0.0018 percent

Helium  (He)

0.0005 percent

Hydrogen  (H2)

0.00006 percent

Xenon  (Xe)

0.000009 percent

________________________

Variable Gases

Water Vapor  (H20)

0 to 4 percent

Carbon Dioxide  (CO2)

0.00385 percent    (estimated June 2008)

Methane  (CH4)

0.00017 percent

Nitrous Oxide  (N20)

0.00003 percent

Ozone  (O3)

0.000004 percent

Particles (dust, soot, etc.)

0.000001 percent

Chlorofluorocarbons  (CFCs)

0.00000001 percent

__________________________

0.00385 percent Carbon Dioxide = 385 parts per million (ppm)

Out of every million air molecules, 385 are CO2 molecules.

"Estimates are that the oceans hold more than fifty times the total atmospheric CO2 content.  Carbon dioxide enters the atmosphere mainly from the decay of vegetation, but it also comes from volcanic eruptions, the exhalations of animal life, from the burning of fossil fuels (such as coal, oil, and natural gas), and from deforestation."

"Deforestation plays a role as cut timber, either burned or left to rot, releases CO2 directly into the air, perhaps accounting for about 20 percent of the observed increase."

Courtesy:  Meteorology Today       C. Donald Ahrens

My conclusion ?  Find something else to worry about.

David 

"It's A Wonderful Forecast"

by David Aldrich

CLICK HERE

Enjoy !

Just got off the phone with my older brother.  He lives in Las Vegas.

He said they are expecting 3 to 6 inches of snow in Sin City by 6 AM tomorrow morning.

The weather guy on the radio said this is the most snow that Las Vegas will have received since 1979.

CLICK HERE

for the answer.

Don't look now.  But some areas in the DEEP SOUTH have received more snow this season than Philadelphia.

Philly's official snowfall so far... 1.3 inches at PHL airport.

Philly's snowfall for last year (Winter 2007-08):  6.3 inches.

New Orleans

CLICK HERE

Houston

CLICK HERE

Dec. 9, 2008: No, you can not see Neil Armstrong's footprint. But go ahead and look: The full Moon of Dec. 12th is the biggest and brightest full Moon of the year.

It's no illusion. Some full Moons are genuinely larger than others and this Friday's is a whopper. Why? The Moon's orbit is an ellipse with one side 50,000 km closer to Earth than the other: diagram. In the language of astronomy, the two extremes are called "apogee" (far away) and "perigee" (nearby). On Dec. 12th, the Moon becomes full a scant 4 hours after reaching perigee, making it 14% bigger and 30% brighter than lesser full Moons we've seen earlier in 2008.

Above: In 2004, Greek amateur astronomer Anthony Ayiomamitis photographed an apogee Moon and a perigee Moon, and set the images side by side to show the difference. [Larger image]

A perigee Moon brings with it extra-high "perigean tides," but this is nothing to worry about, according to NOAA. In most places, lunar gravity at perigee pulls tide waters only a few centimeters (an inch or so) higher than usual. Local geography can amplify the effect to about 15 centimeters (six inches)--not exactly a great flood.

Okay, the Moon is 14% bigger, but can you actually tell the difference? It's tricky. There are no rulers floating in the sky to measure lunar diameters. Hanging high overhead with no reference points to provide a sense of scale, one full Moon looks much like any other.

  The best time to look is when the Moon is near the horizon. That is when illusion mixes with reality to produce a truly stunning view. For reasons not fully understood by astronomers or psychologists, low-hanging Moons look unnaturally large when they beam through trees, buildings and other foreground objects. On Friday, why not let the "Moon illusion" amplify a full Moon that's extra-big to begin with? The swollen orb rising in the east at sunset may seem so nearby, you can almost reach out and touch it.

But you still won't be able to see Armstrong's footprint. Not even Hubble can do that. The Moon is 384,400 km away (on average). At that distance, the smallest things Hubble can distinguish are about 60 meters wide. The biggest pieces of left-behind Apollo equipment are only about 9 meters across and smaller than a single pixel in a Hubble image.

What you will see is the world around you. This is both the brightest and (in the northern hemisphere) the highest-riding full Moon of the year. If you go outside around midnight it will be close to overhead and act like a cosmic floodlamp making the landscape absolutely brilliant, especially if there's snow. Full moons are always high during winter and, indeed, the solstice is right around the corner on Dec. 21st.

A fun experiment: Take a friend outside on Friday evening and ask if they notice anything unusual. Is the Moon big and bright enough to impress the unwary? Explain perigee later....

Author: Dr. Tony Phillips | Credit: Science@NASA

CLICK HERE

Seasonal forecasting is extremely tricky.  It is NOT an art form that I profess to have mastered.

It often relies heavily on indices being positive or negative (like the North Atlantic Oscillation (N.A.O) and Arctic Oscillation (A.O.)) or on history repeating itself.  For example, determining a set of analog years and assuming the average of those years must equal our future.

Some also assume if October (-0.6 degrees below normal in Philly) and November (-1.5 degrees below normal in Philly) are cold, then we will automatically be cold for the rest of winter.  Think of this as a persistence forecast.  This method has pitfalls as well.  Just because it is cold, for example, does not mean it is going to be snowy.

Now that you understand the challenge, here is my take on the 2008-2009 Winter Season.

So far, we have had 1.0 inch of snow at PHL.  It came on November 21st.   

My prediction ?  

 ____________  

WEAK La Nina 

More variability this year than last.  Last year we had a very STRONG La Nina. 

Negative NAO December

Colder and Snowier than normal

Positive NAO January

Warmer than normal.  Less snow than normal.  

Variable NAO February & March

The true wildcards  

More snow than last year.  

Winter 2007-2008

6.3 inches  

My prediction for 2008-2009 

10 to 14 inches for PHL airport

The 2008 Hurricane season is now over.

We had 16 named storms. 

8 Hurricanes.

5 Major hurricanes that include:

BERTHA

GUSTAV

IKE

OMAR

PALOMA

Some of these names will likely be retired.  You'll have to wait until Spring 2009 for an official announcement.

CLICK HERE

Spectacular Conjunction

Nov. 24, 2008: This story ends with the best sky show of the year--a spectacular three-way conjunction of Venus, Jupiter and the crescent Moon.

It begins tonight with a sunset stroll.

At the end of the day, when the horizon is turning red and the zenith is cobalt-blue, step outside and look southwest. You'll see Venus and Jupiter beaming side-by-side through the twilight. Glittering Venus is absolutely brilliant and Jupiter is nearly as bright as Venus. Together, they're dynamite:

Above: Venus and Jupiter converging over Hawaii on Nov. 19, 2008. Photo credit and copyright: Stephen O'Meara. [Larger image]

Add another stick of TNT and voila!—it's tomorrow. Go outside at the same time and look again. You’ll be amazed at how much the Venus-Jupiter gap has closed. The two planets are converging, not in the slow motion typical of heavenly phenomena, but in a headlong rush—almost a full degree (two full Moon widths) per night. As the gap shrinks, the beauty increases.

On Nov. 29th (sky map) the two planets will be less than 3 degrees apart and you'll think to yourself "surely it can't get any better than this."

And then it will. On Nov. 30th (sky map) a slender 10% crescent Moon leaps up from the horizon to join the show. The delicate crescent hovering just below Venus-Jupiter will have cameras clicking around the world.

Dec. 1st (sky map) is the best night of all. The now-15% crescent Moon moves in closer to form an isosceles triangle with Venus and Jupiter as opposing vertices. The three brightest objects in the night sky will be gathered so tightly together, you can hide them all behind your thumb held at arm's length.

The celestial triangle will be visible from all parts of the world, even from light-polluted cities. People in New York and Hong Kong will see it just as clearly as astronomers watching from remote mountaintops. Only cloudy weather or a midnight sun (sorry Antarctica!) can spoil the show.

Although you can see the triangle with naked eyes--indeed, you can't miss it—a small telescope will make the evening even more enjoyable. In one quick triangular sweep, you can see the moons and cloud-belts of Jupiter, the gibbous phase of Venus (69% full), and craters and mountains on the Moon. It's a Grand Tour you won't soon forget.

Right: A sky map of the triple conjunction on Dec. 1, 2008. More maps: Nov. 24, 25, 26, 27, 28, 29, 30, Dec. 1 2008.

Finally, look up from the eyepiece and run your eyes across the Moon. Do you see a ghostly image of the full Moon inside the bright horns of the crescent? That's called "Earthshine" or sometimes "the da Vinci glow" because Leonardo da Vinci was the first person to explain it: Sunlight hits Earth and ricochets to the Moon, casting a sheen of light across the dark lunar terrain.

By itself, a crescent Moon with Earthshine is one of the loveliest sights in the heavens. Add Venus and Jupiter and … well ... it's time to stop reading and go mark your calendar:

Dec. 1st @ sunset: Sky show of the year!

Author: Dr. Tony Phillips | Credit: Science@NASA

Solar Wind Rips Up Martian Atmosphere

Nov. 21, 2008: Researchers have found new evidence that the atmosphere of Mars is being stripped away by solar wind. It's not a gently continuous erosion, but rather a ripping process in which chunks of Martian air detach themselves from the planet and tumble into deep space. This surprising mechanism could help solve a longstanding mystery about the Red Planet.

"It helps explain why Mars has so little air," says David Brain of UC Berkeley, who presented the findings at the 2008 Huntsville Plasma Workshop on October 27th.

Billions of years ago, Mars had a lot more air than it does today. (Note: Martian "air" is primarily carbon dioxide, not the nitrogen-oxygen mix we breathe on Earth.) Ancient martian lake-beds and river channels tell the tale of a planet covered by abundant water and wrapped in an atmosphere thick enough to prevent that water from evaporating into space. Some researchers believe the atmosphere of Mars was once as thick as Earth's. Today, however, all those lakes and rivers are dry and the atmospheric pressure on Mars is only 1% that of Earth at sea-level. A cup of water placed almost anywhere on the Martian surface would quickly and violently boil away—a result of the super-low air pressure.

Above, right: An artist's concept of ancient Mars with abundant air and water. [Larger image]

  So where did the air go? Researchers entertain several possibilities: An asteroid hitting Mars long ago might have blown away a portion of the planet's atmosphere in a single violent upheaval. Or the loss might have been slow and gradual, the result of billions of years of relentless "sand-blasting" by solar wind particles. Or both mechanisms could be at work.

Brain has uncovered a new possibility--a daily ripping process intermediate between the great cataclysm and slow erosion models. The evidence comes from NASA's now-retired Mars Global Surveyor (MGS) spacecraft.

In 1998, MGS discovered that Mars has a very strange magnetic field. Instead of a global bubble, like Earth's, the Martian field is in the form of magnetic umbrellas that sprout out of the ground and reach beyond the top of Mars' atmosphere. These umbrellas number in the dozens and they cover about 40% of the planet’s surface, mainly in the southern hemisphere.

For years, researchers thought the umbrellas protected the Martian atmosphere, shielding pockets of air beneath them from erosion by the solar wind. Surprisingly, Brain finds that the opposite can be true as well: "The umbrellas are where coherent chunks of air are torn away."

Above: Solar wind blowing against Mars tears atmosphere-filled plasmoids from the tops of magnetic umbrellas. Credit: Graphic artist Steve Bartlett. [Larger image]

Addressing his colleagues at the Workshop, he described how he made the discovery just a few months ago:

Brain was scrolling through archival data from Global Surveyor's particles and fields sensors. "We have measurements from 25,000 orbits," he says. During one of those orbits, MGS passed through the top of a magnetic umbrella. Brain noticed that the umbrella's magnetic field had linked up with the magnetic field in the solar wind. Physicists call this "magnetic reconnection." What happened next is not 100% certain, but Global Surveyor's readings are consistent with the following scenario: "The joined fields wrapped themselves around a packet of gas at the top of the Martian atmosphere, forming a magnetic capsule a thousand kilometers wide with ionized air trapped inside," says Brain. "Solar wind pressure caused the capsule to 'pinch off' and it blew away, taking its cargo of air with it." Brain has since found a dozen more examples. The magnetic capsules or "plasmoids" tend to blow over the south pole of Mars, mainly because most of the umbrellas are located in Mars' southern hemisphere.

Above: Dave Brain of UC Berkeley presented this slide at the 2008 Huntsville Plasma Workshop to explain in cartoon fashion how plasmoids carry air away from Mars. [Larger image]

Brain isn't ready to declare the mystery solved. "We're still not sure how often the plasmoids form or how much gas each one contains." The problem is, Mars Global Surveyor wasn't designed to study the phenomenon. The spacecraft was only equipped to sense electrons, not the heavier ions which would make up the bulk of any trapped gas. "Ions and electrons don't always behave the same way," he cautions. Also, MGS sampled the umbrellas at fixed altitudes and at the same local time each day. "We need to sample many altitudes and times of day to truly understand these dynamic events."

In short, he told the audience, "we need more data."

Brain is pinning his hopes on a new NASA mission named MAVEN. Short for "Mars Atmosphere and Volatile Evolution," MAVEN is an upper atmosphere orbiter currently approved for launch to Mars in 2013. The probe is specifically designed to study atmospheric erosion. MAVEN will be able to detect electrons, ions and neutral atoms; it will be able to measure both magnetic and electric fields; it will travel around Mars in an elliptical orbit, piercing magnetic umbrellas at different altitudes, angles, and times of day; and it will explore regions both near and far from the umbrellas, giving researchers the complete picture they need.

If magnetized chunks of air are truly being torn free, MAVEN will see it happening and measure the atmospheric loss rate. "Personally, I think this mechanism is important," says Brain, "but MAVEN may yet prove me wrong."

Meanwhile, the Mystery of the Missing Martian Air is shaping up to be a ripping good yarn.

Author: Dr. Tony Phillips | Credit: Science@NASA

How much SNOW are you dealing with this morning ?

Leonard from Chester County (Westtown) reports 2.5 inches.

Feel free to leave your totals.

Remember, snow showers (even lake effect) is the story of the HAVES and HAVE NOTS.

NIGHT LAUNCH: The sound of a space shuttle blasting off its launch pad is a bone-rattling, remember-it-for-the-rest-of-your-life experience. The view isn't bad either:

Mike Deep of Titusville, Florida, took the picture on Nov. 14th shortly after space shuttle Endeavour executed a spectacular after-dark launch from Kennedy Space Center. "The combination of the launch, a nearly full moon, high cirrus clouds, and some low haze made for an amazing show," he says. "There was even a brief moondog ten minutes before launch. I used a Canon 30D to take these pictures."

Endeavour is now en route to the ISS where it will dock and deliver more than 14,000 pounds of supplies and equipment. The station will receive a new toilet and kitchenette, extra sleeping quarters, and a waste recycling system necessary to expand the crew from three to six in the spring of 2009. NASA describes the mission as "home improvement."