From the ABC 7 Weather team

Archive for March 2012

Auroras appearing from the geomagnetic storm (Video)

March 9, 2012 - 09:24 AM
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The fierce geomagnetic storm wasn't quite as potent as space weather forecasters thought at first but it is now ramping up and plenty strong to cause some beautiful auroras to show up across the globe. Check out some of these awesome pictures coming in to Spaceweather.com from places such as RussiaFinland and Iceland. There are even some videos coming in as well.

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Mother Nature’s March Madness (VIDEO)

March 6, 2012 - 10:24 AM
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Following the Leap day tornado outbreak that spawned 33 reported tornadoes and impacted seven different States, including Nebraska, Missouri, Kansas, Illinois, Kentucky and Tennessee. Many of the same states braced for yet another round of severe weather just two days later. On Friday March 2nd all of the severe weather “ingredients” were there, which ultimately led to the devastating, destructive and likely historic March tornado outbreak. During the early morning hours Friday the SPC, “Storm Prediction Center” already had portions of the Ohio and Tennessee Valleys under a moderate risk. 
          Convective Outlook - Valid 02/1200Z-03/1200Z - NOAA/NWS

The main threat in this area was for a few long-track, strong tornadoes. Later that morning the SPC upgraded parts of southern Indiana, Kentucky, and Tennessee to a High Risk. High risks are reserved by the Storm Prediction Center for rare events and therefore they are only issued a few times each year.

 
          Convective Outlook - Valid 02/1300Z-03/1200Z - NOAA/NWS 

At 9:55 AM the SPC issued the first of three PDS Tornado Watches, “Particularly Dangerous Situation.” The first PDS focused on portions of central and southern Illinois, central and southern Indiana, western Kentucky, and southeast Missouri. The storm prediction center stated that “destructive tornadoes, large hail to 2.5 inches in diameter, wind gusts to 70 mph, and dangerous lighting are possible in these areas.” In all, on this day, the Storm Prediction Center issued three Severe Thunderstorm Watch Boxes, three PDS Tornado Watches, and seven Tornado Watch Boxes. There were 654 warnings issued by local National Weather Service offices, including Tornado, Severe Thunderstorm, and Flood warnings. The first of 279 total Tornado Warnings were issued at approximately 10:42AM for north-central Alabama and southeast Tennessee. In addition, there were more than 400 reports of large hail and nearly 300 damaging wind reports spread across nine different States.

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After a record warm winter, are we in for a hotter than average summer?

March 6, 2012 - 05:00 AM
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Winter 2011-2012, in D.C., ranked the third warmest with an average high of 43.4°.  With all of the "warmer than average temperature" talk I've been hearing, I thought it would be neat to look back at past record breaking warm winters to see if there is a correlation between above average winters and above average summers. 

We all remember 2010 and 2011's scorching temperatures.  The average summer high, for both years, was roughly 81°, about 3° above average.  But looking back at both 2010 and 2011's winters, they were both about 2 to 3° below average.

Here's a list of the top 10 warmest winters in D.C.   I've also added the following summer's averages and how far above or below those temperatures deviated from average.

 
From this list, you can see there is nothing that really stands out.  Out of the ten warmest winters, about half of the summers after were above average and the other half below average for summer temperatures. 

Here's another list of the top ten warmest summers. I've also included the winter averages for those years. 

 
Again, no real correlation, as the 10 warmest summers had a mix of above average and below average winters.  So if you're wondering what kind of a winter we can expect, it looks like past climate data isn't really steering us in any particular direction. 

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Monday's snowfall totals from Central Virginia to Southern Maryland

March 5, 2012 - 02:34 PM
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Did you see any snow today? Chances are if you were in the D.C. area, it was limited to a couple flurries or snow showers. That is nothing like what was falling this morning in parts of Central Virginia. Barboursville, VA in Orange County seemed to be hit the worse, with 10 inches of snow. Where is Barboursville? Here's a nice little map to give you a good idea as it lies just to the northeast of Charlottesville.


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Other areas around Charlottesville and Staunton reported up to 6 inches of fresh, powdery snow. Here's a look in a map form of how much snow was reported and where.

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Ready to spring forward? Not just the season, but the time!

March 4, 2012 - 08:26 AM
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After a whopping 2 inches of snow for the nation’s capital this winter, spring is on the horizon and coming quickly. Even better for those yearning to grab a tennis or golf match after work following the deep, dark days of winter, we get the pleasure to spring forward in just a week!

We’ve been on Eastern Standard Time since November but early next Sunday, March 11, we turn the clocks ahead by an hour at 2 a.m. and Daylight Saving Time begins!

What does this mean for us? First of all, we lose an hour of sleep next weekend (Boo!) but the benefits will outweigh that loss of sleep if you like to see more daylight during the latter half of the day. Keep in mind, too, that turning the clocks ahead by an hour means more darkness in the morning (at least temporarily because the days continue to get longer and longer until June 21!)

Take a look at the upcoming sunrise/sunset calendar. Take note of the last column, change in daylight from the previous day!

Sunday, March 11th Sunrise/Sunset 7:25 a.m.; 7:12 p.m. (+2 min 33 seconds)
Monday, March 12th 7:23 a.m./7:13 p.m. (+3 minutes)
Tuesday, March 13th 7:22 a.m./7:14 p.m (+2 minutes)
Wednesday, March 14th 7:20 a.m./7:15 p.m. (+3 minutes)

Do you remember when the government altered the dates we spring forward and fall back? Yes, it was the Energy Policy Act of 2005, passed by Congress on July 29, 2005 and signed into law by President George W. Bush on Aug. 8, 2005. As a part of this law, clocks were set ahead one hour on the second Sunday of March instead of the first Sunday in April and set back one hour on the first Sunday in November instead of the last Sunday in October.

The whole concept of this measure was to save energy. The idea is that Americans use less energy in the morning before work because they spend less time between waking up and going to work as opposed to the end of the day when more waking hours are spent between coming home from work and going to sleep. This resulted in more energy use in the evening than the morning.

In the spring, turning the clocks ahead an hour three weeks ahead of time would mean longer periods of daylight in the evening (with sunsets an hour later) and reduced energy consumption with respect to the number of hours of lighting needed inside the house in the late afternoon to early evening.

According to this government report, electricity consumption was down by 0.03 percent two years following the passage of this legislation in 2007. On a daily basis there was a 0.50 percent savings on electricity in March compared to a 0.38 percent savings in the fall (November).

No matter how you slice it or dice it, the days are getting longer and you’ll need less lighting for the next few months. Today there will be 11 hours, 29 minutes and 1 second of daylight. By the Vernal Equinox on March 20th at 1:14 a.m. EDT, there will be 12 hours of daylight and 12 hours of night. Then, following the first official start of summer on June 20, 2012 at 7:09 p.m. EDT, there will be 14 hours, 53 minutes and 54 seconds of daylight on June 21st!

Interested in the official start dates of the astronomical seasons through 2020? Click here.

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Dual Pol Part 2

March 2, 2012 - 09:30 PM
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Part 2 of a guest blog by Greg Schoor NWS, Baltimore Washington  

 What are the new products available with Dual-Pol?

There are three base products, each of them go into creating the Hydrometeor Classification (HC) product, previously mentioned. One of the best ways examples to show each of the new Dual-Pol products and what purpose they can serve is to go through case with hail in a thunderstorm. Starting off with what we are more used to seeing, the lowest tilt Reflectivity product. A white oval surrounds the area just north of the storm’s updraft where large hail is likely falling. Reflectivity, however, only shows how “reflective” the surfaces of raindrops, hail, ice and snowflakes, not giving much more information about the echo.

 

 

ZZZZZ

 However, when hail is present and mixed in with rain, different characteristics can be seen with Dual-Pol products that cannot be detected by conventional radar. Looking at Correlation Coefficient (CC) product gives us a few key pieces of information:

1). Which echoes are precipitation and non-precipitation (ground clutter).
2). Where echoes are the same type of precipitation and where there is a mix of different precipitation types. The magenta and dark reds are where precipitation types are the same, in this case, all rain. Once you see a mix of lighter oranges and yellows, there is a mix of other precipitation types, in this case, hail.
3). The white circle denotes the same region in the Reflectivity image that is the core of hail.

 

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Severe weather strikes the Tennessee and Ohio Valleys

March 2, 2012 - 03:18 PM
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In what will be the biggest tornado outbreak since the April 27-28 Outbreak of last year, today has already seen numerous reports of tornadoes and damage across the U.S. A High Risk for severe storms was put out by the Storm Prediction Center. That only occurs a few times per year and so far this system has lived up to the warning. Be sure to check out all of the links below to follow the system and keep an eye on it as it heads east.

Storm Chaser's Live Cams - This is the only one I could get to work as of late as I am sure these sites are getting a ton of traffic.

Storm Chaser's Live Camera on Ustream

More Storm Chasers Cams from TornadoVideos.net

Storm Reports so far today

Current Watch Boxes

Storm Analysis Products for Weather Enthusiasts and Meteorologists

 Below you can see on the left a reflectivity image of a supercell thunderstorm located to the north of Louisville, KY with a noticable debris ball at the bottom of the comma. This signifies debris in the atmosphere picked up on radar that could only be there by a tornado on the ground.

Reflectivity and Velocity Image of a storm just north of Louisville, KY

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Climate statistics for Meteorological Winter

March 2, 2012 - 04:00 AM
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March 1st is known as the start of Meteorological Spring. The period that meteorologists use to keep climate records for winter (December through February) is now over. Let's go over some of the numbers provided to us by the National Weather Service office in Sterling, VA.

Temperatures

Dulles Airport ranked as the warmest winter of all time with an average of 40.1 degrees. This breaks the previous mark of 39.8 degrees set back in 2001-02. Remember the climate record only goes back to 1963 at Dulles.

Reagan National posted its 3rd warmest winter of all time. This is behind the 1931-32 and 1889-90 winters.

BWI Thurgood Marshall recorded its 7th warmest winter of all time and the warmest winter since 1949-50.

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Severe weather threatens the Tennessee Valley again Friday

March 1, 2012 - 11:44 AM
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After Tuesday and Wednesday were extremely active with numerous reports of tornadoes and damaging winds, it appears the chance for severe weather will return for Friday. This isn't expected to affect the D.C. area, but it will have a big impact to regions that experienced the severe storms over the past two days. The bullseye for tomorrow's severe weather will again lie over the Ohio and Tennessee Valleys from Southern Ohio to northern Alabama.

Friday's Outlook for severe weather from the Storm Prediction Center

In those areas, strong long-track tornadoes will be possible. I was looking at the set up with Meteorologist Adam Caskey and we both agreed this looks like a very serious and dangerous situation. The set up shows all of the ingredients will be in place. This includes the necessary moisture, lift and shear to produce tornadoes. It's one of those times that if you know people in the area such as friends or relatives, give them a call and a heads up.

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