Lightning captured by Raul Heinrich striking the CN Tower in Toronto July, 23rd 2008

Let's just make this clear from the get go: we know little to nothing about this phenomenon. In fact, for many years ball lightning was thought to be something made-up or misinterpreted by eye witnesses. Through the rapid increase in photographic and video technology, we've added many more cameras to the world and through these observations scientists have begun to acknowledge that ball lightning exists... but now the real questions arise: what is it, and how does it form?

So we’ll start with the basics. Regular lightning itself is still quite an enigma to researchers, but at least we feel we’re beginning to grasp the foundations of how it’s created. It’s generally accepted that as a thunderstorm begins to form from a rapidly rising current of air (updraft), the water droplets eventually reach the freezing level where ice begins to form. Scientists now believe it’s the interaction between ice and water in a thunderstorm where electrical charges are exchanged and eventually dispersed into the cloud. In the most basic sense, most storms gather a positive charge at the top of the cloud while a negative charge forms at the base. Knowing that opposite charges are attracted to each other, the negative charge at the bottom of the storm induces the ground below it into a positive charge. If the storm eventually builds up enough of a charge, the energy is released as a lightning bolt from the cloud to the ground. Remember how we just talked about the negative and positive charge in the cloud itself? This difference can also create a lightning bolt within the cloud. In fact, most lightning bolts are intracloud lightning… roughly 75%-80% of the lightning a cloud produces. 

Lightning strike panorama over Bucharest, Romania on June 26th, 2007 by Catalin.Fatu at en.wikipedia

Lightning captured by Raul Heinrich striking the CN Tower in Toronto July, 23rd 2008

That’s basically how lightning forms, so what about “ball lightning”?

Since the dawn of man, people have given many descriptions of ball lightning. Most accounts talk about the sight of a glowing ball of light (about the brightness of a 100 watt bulb) anywhere from the size of a tennis ball, to the size of a beach ball. Almost all accounts talk about seeing some sort of glowing ball in the air. Sometimes reports have the ball dropping towards the ground and moving around very quickly and erratically. Some people say the ball travelled from outside to inside a house or building through and open door or window, sometimes scorching the floors and walls on its way before it vanishes. Other stories tell tales of the lightning balls fusing metal together, disrupting electrical wiring and/or equipment, and even scorching or killing people! Ball lightning accounts range from people experiencing highly electrical thunderstorms, to others saying the ball burst out of “thin air” from a gentle rain on a cloudy/cool day.

The leading theories around ball lightning all eventually point to the formation of something called “plasma”. Plasma is something thrown around in all sorts of science-fiction books and films, but it is a real thing - most recently associated with flat screen televisions. Plasma (as defined by dictionary.com) is “a highly ionized gas containing an approximately equal number of positive ions and electrons.”

WHAT??? 

Let’s look at something you’re probably a bit more familiar. You’ve seen one of these, right? 

Photo courtesy: Luc Viatour / www.Lucnix.be

I like to sum up the notion of plasma as electrified gas/air that acts more like a fluid. Now imagine taking the “electrical strands” you see in the toy plasma lamp, scrunch them up into a ball and that’s pretty much what experts believe to be ball lightning. 

So imagine that you’re just minding your business, when all of a sudden you see a bright flash, hear a tremendous boom, then see a glowing ball in the air! I find ball lightning so interesting because it’s seems to be a phenomenon that people rarely even think about, and when it does occur it’s a complete surprise! 

Ball lightning stories even have a local flavor. Our own chief meteorologist Doug Hill has a family account of witnessing a ball lightning event! According to his mother and her brothers and sisters, when living just right off the Inner Harbor in Baltimore a lightning ball came right through a wooden framed screen door in the front of the narrow, shotgun style home, travelled down the wooden floor leaving scorch marks in its wake, before exiting through the back screen door! 

Through researching this topic, I found a great website that has an extensive log of personal ball lightning accounts: http://amasci.com/weird/unusual/bl.html
There also happens to be a really cool case study that was performed on a ball lightning account in Queensland, Australia back in 2002. Here’s a link to their page: 

http://www.ernmphotography.com/Pages/Ball_Lightning/BL_Gallery1.html 

Lucky for us, a photographer caught the event! Here are some of his photos:

Courtesy of: ERN Mainka

Courtesy of: ERN Mainka

Courtesy of: ERN Mainka

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Some changes have been starting to take place in the weekend beach forecast. Overall it still looks like it will be nice for the Delmarva Beaches down to Virginia Beach. There are questions though as a new system has developed just to the east of Florida which may become another tropical system. This could really put a big question mark for the forecast for the Outer Banks and the Southeast. Here are our latest thoughts.

All the information you need to know about the beaches here!

Delmarva Beach Resource Guide

Saturday & Sunday Beach Forecast

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Well, it’s that time of the year again when we will be monitoring the tropics daily for potential tropical development. The 2012 Atlantic Hurricane Season officially begins June 1st and will conclude November 30th. However, storms can and have formed both before and after the official season just like we saw already this year with Alberto. Tropical Storm Alberto formed off the South Carolina coast on Saturday May 19th and then weakened into a post tropical depression as it moved back into the cooler waters of the Atlantic by May 22nd.

The official forecast from the National Oceanic and Atmospheric Administration (NOAA) was released this morning, May 24th at 11:00 EST. Their forecast is for a near normal hurricane season with a 70 percent chance of nine to 15 names storms. Of those, four to eight will become hurricanes with maximum sustained winds of 74 mph or higher. From the four to eight hurricanes they believe that one to three of those storms will become major hurricanes, which are category 3 or greater. An average hurricane season produces 12 named storms, 6 hurricanes and 3 major hurricanes.

It is important to note that no matter if the official forecast is for an above, below or average number of hurricanes that preparation is paramount. For example, in 1992 that hurricane season only produced six names storms however one of those storms was Andrew. Andrew made landfall in south Florida as a Category 5 storm that devastated that region. A quote that is always in my head is that it only takes one and with memories from Irene still fresh in resident’s minds everyone should have a hurricane plan and be prepared to use it should a storm take aim on our area once again.

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Heavy rain, thunder, and LIGHTNING... oh my! 

Check out this timelapse from atop our ABC7 Studio in Arlington (courtesy of our WeatherBug camera). As a strong storm cell moved over the area, you can see the dark skies, raindrops on the camera lens, and an awesome end frame... take a look!

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Updated Wednesday May 23: Wow, do you see the last time this post was updated? April 30th! We haven't even been close to breaking 90 degrees at Reagan until this week. I think there are numerous chances and they all lie over the Memorial Day weekend. This could be the 2nd year in a row we hit 90 degrees on May 26th. Last year it 92 on May 26th. Thank you Chuck Bell and Twitter for that, for some reason I missed that before posting! If you haven't voted be sure to continue to get those votes in as we're still taking them in! Good luck!

Vote here: abc790degreecontest@gmail.com

Updated Monday April 30: Will Reagan National finally hit the 90 degree mark this week? Signs are pointing to yes for this Friday. This comes interestingly enough after a period of 7 of the past 8 days seeing temperatures below normal. The last time THAT happened was back in late October and early November of 2011. 6 months ago! If today is below normal that will make for the past 8 out of 9 days. So of course it would seem fitting that we would hit the 90 degree mark only 5 days later. Time will tell! 

Updated Tuesday, April 17: Reagan National hit 89 degrees yesterday which was the warmest day so far this year but still no 90 degree day. As of now the 7-day forecast doesn't show any temperatures even in the 80s let alone 90. When do you think the area will get to 90 degrees? Keep those guesses coming in! I wouldn't mind wearing the ABC 7 swagger around in the form of a t-shirt, hat and umbrella.

Send your guesses to abc790degreecontest@gmail.com and good luck!

Updated Wednesday, April 11: Nothing like a little snow and graupel across the region to get you excited about a 90 degree day contest! With highs in the 50s today, it's hard to believe the temperatures will be pushing the low to mid 80s by the start of next week. There are still a lot of submissions coming in for the contest to be sure to submit your guess for the first day that it will reach 90 degrees at Reagan National. You can win an ABC 7 umbrella, t-shirt and a hat if you happen to guess correctly as well as see your name on the News. Good luck!

Send your guesses with your name and email adress to abc790degreecontest@gmail.com  

Updated Thursday March 29: Another day has gone by and there doesn't seem to be a 90 degree day in sight, though it can't be too far off! The record high for today is 92 degrees at Reagan National, set back in 1907. As we get into April, more often than not the record high for the day is in the 90s. There are actually only 8 days in April that have record highs below 90 degrees. Be sure to send in your guesses as there are already tons of submissions! Good luck!

Original Post Below:

As the D.C. area has seamlessly transitioned into Spring and early summer, it got us thinking about when the first 90 degree day will be. It's not quite that time of year yet but it will be upon us soon enough. Remember last year? Reagan National had the second warmest summer on record at an average of 81.1 degrees F, which was only second to the summer of 2010 which had an average temperature of 81.3 degrees F.

2011 included 50 days at or above 90 degrees. Six record highs were broken during the summer and 3 days were at or above 100 degrees. The hottest day was on July 29 when the temperature soared to 104 degrees at Reagan National. That same day the temperature hit 106 degrees at BWI Marshall.

So will this summer be just as bad? Meteorological Spring has started off very warm with temperatures in the 80s 3 days in a row including a record breaking 82 degrees on March 15. Are we close to our first 90 degree day? Climate statistics would tell you we aren't. Check out the first day Reagan National hit the 90 degree mark over the past 20 years.

First 90 degree day for the past 20 years

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On June 5th, 13 days from now, the transit of Venus will occur and can be seen during the evening and through sunset. This is when Venus passes directly between the earth and the sun and we see the distant planet as a small dot passing slowly across the face of the sun. Interestingly and historically, this rare alignment is how we measured the size of our solar system. For those of you who have smart phones, there’s an app for this. The phone app is creatively called the VenusTransit phone app and will actually allow everyone to send their observations of the transit to participate in a global experiment to measure the size of the solar system. Do not try to observe the transit of Venus directly! You must use proper eye protection at all times with the proper solar filters. You still have time to order a pair of glasses online and here is a place where I know you can get them dirt cheap. Enjoy the show!

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The clouds and partial clearing set the stage for a picture perfect sunrise over our nation's capital this morning.  If you hit the snooze button and missed the spectacle, the WJLA roofcam has you covered and captured the scene in this timelapse video.  Enjoy!

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“THIS IS AN EXTREMELY DANGEROUS TORNADO WITH COMPLETE DEVASTATION LIKELY. … SEEK SHELTER NOW! … MOBILE HOMES AND OUTBUILDINGS WILL OFFER NO SHELTER FROM THIS TORNADO — ABANDON THEM IMMEDIATELY.” Pretty ominous statement but this and other similar apocalyptic statements from the National Weather Service have been, and will be issued experimentally this tornado season in Missouri and Kansas in an effort to have us make a better life or death decision. Yet only 60 years ago, the then U.S. Weather Bureau would not issue a tornado alert for fear of causing widespread public panic.

The first public tornado risk statement was given by broadcast meteorologist, Harry Volkman in March 1952, who was afraid of being arrested by the government for communicating (correctly) there was a tornado “risk” for central Oklahoma. My  science of meteorology has made incredible advances in understanding and forecasting short-term life threatening weather such as tornadoes. Do we know everything? Is the science of tornado prediction “settled”?  In Joplin, MO, in 1970, in 1990 or now? Of course not. There is much to learn and still about 70% of tornado warnings are false alarms- there is no tornado. But we make a decision. Sometimes as many tragic stories from the devastating tornado season last year, the decision was not take shelter. Lives were lost. But the terrible tornado season last year also lead thousands of Americans in or near “tornado alley” to make the decision to purchase a “safe room” for their home. Joplin, Missouri, the city almost destroyed by a rare EF-5 monster one year ago, will spend $26 Million (with federal funding) for safe shelters for their schools. A good decision? Probably after the tragedy and near tragedy of last year, yes a good decision. Forecasting tornadoes still has many uncertainties, yet if a tornado warning is issued, we all have to make a short-term decision. Now more of us will head to a safe room and not worry if this is another false alarm. There will never be 100% certainty in forecasting tornadoes, but we will make a “best”decision.

The science of meteorology through satellite observations, computer “models” and continuing basic and applied research has also made impressive progress in forecasting the track and intensity of hurricanes.

Rather than minutes or hours, Americans in the possible path of a hurricane have to make a decision. Days ahead.  Do I evacuate? Do I believe the forecast? There is that cone of uncertainty . . . do I take a chance? Is the science of hurricane forecasting, “settled”? Again of course not, but decisions, human and economic decisions effecting sometimes millions are made, knowing the exact outcome is uncertain.

Supposedly the great Yogi Berra said, “It’s tough making predictions, especially about the future”. However, we make decisions every day about some prediction whether it is the traffic during rush hour, canceling a weekend picnic or headed with my family to a shelter when I hear a tornado siren.

Why should a decision about what action we take based on expert outlooks for our climate and national, regional and local changes 50 or 100 years from now be any different than making a decision, taking actions, minutes, hours, days or even a week from now knowing the tornado or hurricane, snow storm or seasonal forecast is also uncertain. The science is not settled but the modern science of forecasting short term weather is solid and the modern science of estimating long term climate changes (yes global warming and it impacts) is solid.  Are either 100% accurate?  Do we require 100% accuracy before making a decision or taking action?  Ask folks in Joplin what they will do the next time a tornado warning siren sounds.

We make decisions every day without 100% certainty, other than the sun will come up. The science of short-term weather and longer-term climate is solid. Neither is 100% certain but look where we have come in 60 years from no alerts to “You could be killed if not underground or in a tornado shelter”. Where will we be in making climate related decisions 60 years from now? Let’s hope history gives us some perspective for our future shared decisions.

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It was a Sunday afternoon, 5:34 PM, one year ago from today, when a supercell thunderstorm spawned an EF5 tornado over Joplin, Missouri.  In just over a half hour, residents' lives changed drastically.  Despite fatalities, property destruction and damage, and a forever changed landscape, the people of Joplin and surrounding communities have come together to show the true power of Americanism. 

Going back to that devastating day, we start with a look at the radar and storm relative velocity at 5:48 PM on May 22, 2011.

NOAA Radar  

The radar (left) is extremely impressive.  The higher/brighter reflectivity shows the extremely heavy rain and hail.  The area circled is the debris ball from the tornado itself.   A hook echo can also be made out surrounding the debris ball.  The storm relative velocity depicts inbound (green) and outbound (red) winds.  The tight couplet shown on the right indicates strong rotation. 

Over 200 mph winds, tracking six miles across the city of Joplin, caused more than a thousand injuries and 160 fatalities.   The Joplin tornado is the deadliest tornado on record since modern tornado record keeping began in 1950 and falls 7th on the list of deadliest in U.S. history.

Google Maps - Path of Joplin Tornado 

               2011 was an unusually active year for tornadoes.  It ranks second as the most active year for tornadoes with 1691 tornadoes recorded (2004 most active year with 1817 tornadoes).  In May 2011, 326 tornadoes were reported.  There were 178 fatalities in May 2011, with 158 of those fatalities due to the Joplin tornado.

NOAA - Joplin Damage

In an effort to prepare and protect people in the wake of severe weather situations, many new initiatives are evolving.  The federal and local (Missouri) goverenments are coming together to fund "weather safe rooms" in new Joplin schools being built.  NOAA continues the "Weather-Ready Nation" intitiative to help spread better information, so people make better decisions.  

Among the overwhelming images of a city succumb to a natural disaster of this magnitude, come images of renewal and revival. The StormWatch7 weather team compiled a photo gallery on the one year anniversary.

On this one year anniversary of the Joplin tornado we remember all those who lost their lives and loved ones in this tragic weather event and the people who continue to pick up the pieces after a life changing event. More photos in this gallery of before and after and today in Joplin

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A low pressure that sat and spun over the Gulf Stream off the South Carolina Coast officially became named Tropical Storm Alberto on Saturday. The storm will start to move away from the Carolina Coast next week, eventually fading into the distance in the cooler water of the North Atlantic by the middle and latter half of the work week. Of course, Alberto formed two weeks before the official June 1 start to the Atlantic hurricane season.

Story Image: Visible satellite imagery from Saturday, May 19th showing Tropical Storm Alberto forming off the South Carolina Coast. Courtesy of the Space Science and Engineering Center (SSEC) at the University of Wisconsin-Madison.

Prior to Alberto, Tropical Storm Aletta stirred things up in the Eastern Pacific at the beginning of the week....forming just one day shy of the start of the Eastern Pacific’s hurricane season. That storm was hundreds of miles from Mexico and the southern California Baja and posed no threat to land.

What we may think of as an “active” start to the tropics actually awakened a “tropical drought” on Earth! Believe it or not, Aletta broke what had been a 41-day streak with no tropical cyclones on the globe! According to the U.K. Met Office, this was the longest stretch without a tropical cyclone in at least 70 years!

Speaking of tropical withdrawl, a record number of days have passed between major U.S. hurricane landfalls. As a matter of fact, that record was shattered even before Christmas! 2,232 days had passed way back on December 4, 2011 since Hurricane Wilma made landfall along the Gulf Coast as a category 3 storm in 2005. Previously, it was between September 8, 1900 and October 19, 1906 where no major hurricanes made landfall in the U.S.

Graph courtesy of Roger Pielke, Jr., professor of environmental studies at the Center for Science and Technology Policy Research at the University of Colorado at Boulder.

So, with two tropical systems kicking things off early this year, should we be extra cautious of how the 2012 Atlantic Hurricane Season might turn out this year? Not necessarily. Let’s look back at two other seasons in recent times where an early start didn’t necessarily equal a busy season.

In 2009, the first tropical depression of the season formed in the same vicinity as Alberto on May 29th. The storm only had a life cycle of one day as a vigorous upper disturbance kicked it off into the cooler water faster than Alberto will be next week. In the 2009 season though only 9 named storms developed. This is two less than the average of 11 for a season.

In 2003, Tropical Storm Ana was the first tropical storm on record in the North Atlantic basin. It became a subtropical storm early on April 20th then later that same day transitioned to a tropical storm as microwave data suggested it had a warm core. Ana formed within 300 miles of Bermuda and then wondered east through the Atlantic, so it posed no threat to land.

An early named storm in that season (2003) lead to an active year with 16 named storms.

The major factor at stake for the upcoming 2012 season is a transition to a weak El Nino which tends to increase upper-level wind shear in the Atlantic, suppressing tropical formation a bit. Therefore, the forecast is for an average to slightly below average season for tropical storm formation. So, while we got an early start, things could level off as the season wears on and El Nino tries to make an appearance.

Of course, stay tuned to the ABC7 Weather Center and WTOP Radio for the latest on any tropical development that may head our way this summer and fall!

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Here we are only 1 week away from the Memorial Day Weekend, the "traditional" beginning of summer. After so much record heat last summer (remember 104° July 29?)  many folks are not ready for heat and humidity. Look at our recent poll.  Boy only 15% say, "Bring it on"

But ready or not, we can't escape summer heat and humidity completely in Washington. So what will the coming summer be like? Another scorcher such as last July, out hottest month ever, with 25 90° days and that high of 104° on July 29th?  Or a break in hot humid summers?  Four of of the last five summers have been hotter than average. Each of our entire weather team has an opinion and the elements we look at include ocean- atmosphere links such as El Nino and La Nina . . . ENSO is neutral right now.   

One element I look at is soil moisture and drought and right now much of the south and southwest soil is dry and much of the area in drought.

It’s conditions like this that can give what we meteorologists call “feedback”. The soil, being very dry, does not absorb heat the way wet soil or the oceans do, but rather reflects heat back into the air and thus the heat feeds back or builds.

I’m afraid with that pattern now established and our warm pattern (12 of 13 months now above average) we are in for another hotter than average summer. But not as hot as last summer (+3.4°) or the summer of 2010 (+3.6°). I know that is being darning. So here is the rundown of what we all think about the coming summer.

Myself – Another hot one - temperatures above average and 35-45 90° days for the summer

Doug - I think it will not be a long, hot summer. Rather a “normal” summer is more likely, I think. If anything, might be a fraction below average temperature wise. Rainfall subject to tropical effects.

Alex - I'm a statistics guy and will go with persistence here. 7 of the past 10 summers have been above normal. I'll continue that but not nearly as hot as the last two. The normal is 77.7 degrees but the last two years have averaged above 81 degrees. I'll go with 78.5 degrees, nothing too excessive!

Adam –I think it'll be a slow start to the summer. We'll have a typical amount of heat and humidity, but I anticipate the final tally of 90 degree days to be near or slightly below average.  To be honest, I don't put much energy into the summer forecast because it's always hot and humid here in the D.C. area - you can't escape it. Sure, some summers are hotter than others and will have a greater impact on sensitve groups of people and some are cooler, but it's still just hot. You'll need your A/C and a pool will always feel refreshing in July in Washington no matter the final statistics.

Brian- Not an extremely hot summer with above average rain. 
Coming off a historically warm March, one may want to leap to the conclusion that the summer will be unbearable. Looking over the past statistics, we have actually had years with below-average summer temperatures following unusually mild, late winter/early springs so don’t fret the cooling bills just yet. Much like we’ve seen the repetitive pattern as of late with extended dry stretches followed up by periods of soaking rain.

Chris - I'm forecasting Summer temperatures that will run "+1.0 degrees above normal."  All told, it will feel like a “typical Mid-Atlantic Summer.” Additionally, I DO NOT think we will have more than one or two periods of prolonged heat (IE: Heat waves) and those periods, IF we see them, would last a week or less. Getting to specific numbers (31-36) 90° d or greater days this Summer, with the majority occurring in July.  I will add that I think this Summer will be rather active in terms of severe weather and storms, so make sure have your emergency kit in order and ready to go. Last, I believe that precipitation this Summer will be average or slightly above average. The wild card in all of this, of course, would be the impact of any tropical system.

Eileen - slightly above average temperatures overall with average to slightly below precipitation

Devon – I'd take a wild stab and say our summer will average "above" for temperatures and average "below" for total rainfall at Reagan National by the time we tally up the initial info. What do I think that REALLY means? I'd say a stretch or two (one or two weeks) of very hot weather, with generally a bearable summer but lacking in total rainfall... if I'm right, get ready to water!

Ryan Miller - I'm going slightly above average temps due in part to neutral ONI and slightly below rainfall values which could aid in bumping temps up.

Steve-I don’t think it will be as hot as last summer, but don’t look for prolonged periods of below average temperatures either. Around 40 90-degree plus days with at least 10 in the upper 90s and a few "super ugly hot days." Total number of days with rain or showers will be limited, but when it does rain, look for significant totals quickly. "

So the final tally is roughly 7 to 3 for a hotter than average summer in the DC area.  A guarantee?  Surely you jest.  There is no skill in day to day forecasts beyond about 7 days so all we can really talk about is the general outlook for the coming summer.

And can't forget what our colleagues at NOAA's Climate Predictiion Center think. The very latest outlook 

So be prepared, but if you don't like heat,  hope that this at least comfortable, low humidity pattern continues . . .and Doug, Adam and Brian are correct and myselfI and 5 of our team are wrong.  Of course keep watching Channel 7, News Channel and right here on WJLA.com.  We'll keep you posted throughout the summer hot, humid or cool and comfortable.

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If you are heading to the beach this weekend, I'm sorry to tell you but it won't be warm and sunny. The pesky low which has been sitting off the southeast coast will have an affect on the Eastern Shore, bringing breezy winds and cooler temperatures as the air flows off the cool ocean. Water temperatures are still in the lower 60s so it makes sense why the air will be so cool. If you are going, Saturday will be the nicer of the two days with a little more sunshine and warmer temperatures than Sunday.

Saturday Beach Forecast for Delaware & Maryland Beaches

Sunday will only be a few degrees cooler overall but the added cloudcover will make it feel even cooler. Be sure to bring the sweatshirt and pants if headed down to sit on the beach. We'll be adding a forecast for the Virginia Beach area and Outer Banks for next weekend's Memorial Day Weekend Beach forecast. Sorry you can't enjoy a warm weekend the quiet week before Memorial Day! Early model guidance is depicting a very warm weekend next week!

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There was just enough of today's waning crescent moon left (6% illumination) to see the sun chase it into the sky early this morning. Enjoy this timelapse from the WJLA roofcam:

By the way, there will be a solar eclipse on Sunday, but we won't be able to view it here on the east coast.

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After a sighting of the supermoon earlier in May, get ready for another spectacular night sight this coming weekend -- a solar eclipse.  Now before I get your hopes up, if you live on the East coast, you won't be able to see the eclipse; however, people in the West and Southwest will get quite a show. 

Diagram of an eclipse 

The solar eclipse will occur Sunday, May 20, 2012. A solar eclipse occurs when the new moon passes directly in between the Earth and the Sun. Now there are different types of eclipses: partial, total, annular, and hybrid. The eclipse visible for folks on the West coast, Sunday, will be an annular eclipse.  This is when most of the sun is covered by the moon (roughly 90%), but a sliver of the outside of the sun is visible -- resembling a ring and sometimes referred to as the "ring of fire".  It is important to those viewing the eclipse that they wear protective eyewear.  Even though most of the sun is covered, you still want to protect your eyes.  If you think about it, you're still looking at the bright sun (although much less of it) and that exposure can be damaging to the retina.

"Ring of Fire" in China

I found a great quote from NASA's leading eclipse expert, Fred Espenak of the Goddard Space Flight Center, giving us his take on eclipse viewing.  Espenak says, "I like to compare different types of eclipses on a scale of 1 to 10 as visual spectacles. If a partial eclipse is a 5 then an annular eclipse is a 9."  Expenak went on to say  "On that scale of 1 to 10, a total eclipse is 'a million!".   A total solar eclipse occurs when the moon covers the entire surface of the sun, so everything gets dark -- the sun is completely hidden!  The last total solar eclipse seen from the United Sates was 18 years ago - May 10, 1994.  If you want to see a total eclipse in the U.S., your time is getting closer -- only 5 years to go. 

So why won't residents in the East coast get to see the annular eclipse?  Well, the sun will have already set by the time the annular eclipse occurs.  The few that will be lucky enough, in the U.S. to catch a glimpse of the annular solar eclipse will be a swath from Northern California to the Texas Panhandle.  The map below also shows where people in the middle of the country will see a partial eclipse.

Even though we, in D.C., won't get to see the eclipse there will certainly be lots of images circulating the internet that we'll be able to ooh and ahh over. 

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Humidity -- we talk about it often in weather.  We mostly reference the humidity when the weather gets warm, but there is humidity all the time -- it just depends on whether it's high or low.  That then leads to how it "feels" outside.  For example, the three H's of summer you're probably familiar with in D.C. - Hazy, Hot, and Humid.  It's one thing to be hot in the summer with temperatures in the 80s and 90s, but factor in the humidity and that's when it can feel downright uncomfortable... and don't even get me started on what it does to my hair!

So what exactly is the humidity?  And why does it make the air feel so "sticky"?  Let's break it down a little.  Humidity is the amount of water vapor in the air.  It's measured in different ways, but you'll most commonly hear it referred as the relative humidity or the dew point.  The image below gives you a visual of the temperature and the amount of water vapor present (think of the beakers as the atmosphere).  The lower the temperature, less moisture needs to be present for the air to become saturated.  The same thought can be applied for warmer temperatures, but you can see more water vapor can be present.

FAA - http://www.aviationweather.ws/026_Water_Vapor.php

Let's start off with relative humidity.  The relative humidity is the amount of moisture in the atmosphere relative to the amount that would be present if the air was saturated.  It sounds confusing, I know.  The relative humidity is expressed as a percentage and is based off the temperature.  We tend to associate rainy days or humid days with higher humidity, which can be true, but it can also be misleading.  Often times the humidity is near 100% in the morning.  The reason is the air is typically cooler in the morning and cooler air holds less water vapor - you can go back to the image above to help visualize this.  The relative humidity is a good measure of humidity; however, it can be a little tricky to understand.  I have always been a fan of the dew point.  

The dew point is the temperature the air has to "cool" to, to become saturated.   I put the word "cool" in quotations, since the dew point can be a fairly high temperature.  Now the dew point temperature will never be greater than the air temperature, but the closer the dew point is to the air temperature, the more water vapor in the air, and the more "sticky" or muggy it feels.  Usually when the dew point gets above 65°, that's when it starts to feel uncomfortable.

For example, if the temperature is 86° and the dew point is 70° it will actually feel like 91°!  The reason it feels hotter is because it's harder for our bodies to cool us off when there is higher humidity.  Our bodies use a process of evaporative cooling, so if there's a lot of water vapor in the atmosphere, it is much harder for our bodies to cool off, as compared to a day when there is less water vapor and lower humidity.  The chart below shows the Heat Index which calculates the temperature and relative humidity to determine how hot it feels to our bodies.  Hot temperatures combined with high humidity can be very dangerous.

NOAA Heat Index

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It was a very soggy start to our Tuesday, but the sun eventually appeared and we caught it all on our rooftop camera.  Here's another great timelapse of the sky over Washington, D.C. from this morning:

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Washington D.C. remains in a  precipitation deficit of more than four inches since January 1st, but we put a nice dent in that deficit with the recent rain.  I'm a happy gardener today!  Here's a breakdown of the highest rainfall totals per county from Monday morning through 9 a.m. Tuesday:

 Washington, D.C.:
• Children’s Hospital: 1.24”
• Lafayette ES: 1.07”

Arlington, VA:
• Washington-Lee HS: 0.90”
• Campbell ES: 0.88”

Fairfax County, VA:
• Centreville: 1.48”
• Oakton: 1.27”
• Fairfax: 1.18”
• Burke: 1.16”

Loudoun County, VA:
• Aldie: 1.30”
• Chantilly: 1.18”
• Leesburg: 0.98”
• Ashburn: 0.97”

Prince William County, VA:
• Dale City: 1.52”
• Manassas: 1.40”
• Woodbridge: 0.95”
• Quantico: 0.87”

Montgomery County, MD:
• Olney: 1.82”
• Gaithersburg: 1.54”
• Germantown: 1.43”
• Rockville: 1.39”

Prince Georges County, MD:
• Adelphi: 1.41”
• District Heights: 1.27”
• Suitland: 1.15”
• Oxon Hill: 1.05”

Charles County, MD:
• Indian Head: 1.16”
• Waldorf (Westlake HS): 0.83”
• Waldorf (Wade ES): 0.56”

Frederick County, MD:
• Myersville: 1.34”
• Monrovia: 1.20”
• Frederick: 1.11”
• New Market: 1.09”

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Ring, Ring -- this was the main use of telephones and cell phones in the beginning, but in today's day in age it's all about mobile apps, GPS, gaming, email, text messaging, video chats, and much, much more!  To be honest, I can hardly keep up with it. 

Smartphones

Now I will say, I do like to keep up with the latest weather apps, since I always like to know what's going on with the weather.  Obviously I'm bias, but I think the StormWatch 7 app for iPhone and Andorid is a great go-to (sorry, had to plug!).  Whether you download weather apps or not, you'll soon start receiving text alerts when severe weather warnings are issued.  

Wireless Emergency Alerts (WEA) are emergency messages sent by authorized government alerting authorities through your mobile carrier.  WEA is a partnership between FEMA, the Federal Communications Commission (FCC), and wireless carriers, to enhance public safety.

Anytime a life threatening weather warning is issued you'll receive a text message.  The National Weather Service will send out alerts such as, tsunami warnings, tornado and flash flood warnings, hurricane, blizzard and a few warnings.  This alert system will also be utilized to send Presidential alerts and Amber alerts.

Now, don't worry - your phone won't start alerting you when there is a tornado warning in Oklahoma, but it will text you if you are in the geographic area with an active warning.   How does your phone know?  An alert will be sent through the nearest cellular broadcast towers, so it is not utilizing GPS and therefore does not know your exact location.  Any WEA-capable phone in that particular area on a participating network will receive the alert.  The text alerts won't cost you anything either. 

The goals is to have these push text messages sent within the next few months.  Some areas have already undergone test text alerts.  You can find out more information here.  

With such highly sophisticated "smart" phones, I think this is a "smart" and effective way of reaching the public and alerting them to pertinent information.  It could help save your life. 

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The D.C area is abnormally dry, and part of the region is facing a drought with a precipitation deficit of more than five inches since January 1st (DCA: 5.21" below normal since 1/1/12).  We need rain, and we're getting it, but will it put a dent in the deficit?  Here's a video indicating the latest prediction from our own computer model (06Z Microcast). 

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Overall, the weekend looks great especially on Saturday. Expect total sunshine and highs near 80° on Saturday with low humidity.  Some upper-level energy should develop clouds on Mother's Day, but temperature are still expected to spike near 80° in the afternoon.  It's worth noting that an few sprinkles are possible over the higher terrain of West Virginia and Western Maryland by Sunday evening, and there's a slight chance a few drops could fall over the Shenandoah Valley late Sunday evening.  Happy Mother's Day to all the moms! 

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