From the ABC 7 Weather team

Archive for September 2012

October weather ushers in lots of fall fun

September 29, 2012 - 12:00 AM
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I can't get over how fast 2012 is flying by!  October is nearly here, we're losing hours of daylight, the temperatures are starting to drop, and I've even seen some of the leaves changing on the trees.  Autumn is my favorite time of year!

So what can we expect for the month of October in D.C.?  Well, we still don't have a crystal ball to say exactly what will happen, but based on current observations and past trends, here's what the Climate Prediction Center is expecting.

Climate Prediction Center
Climate Prediction Center

Overall, temperatures may be a bit above average with near average rainfall.  That's certainly a good thing since it still remains rather dry across the region.  The wettest October on record was actually just back in 2005 with 9.41" of rain!   I know we need the rain, but that's too much for one month.  Temperatures to start the month of October average a high of 74° and a low of 56°.  By the end of the month, the average high is only 64° and 46° is the average low. 

Even though the averages don't get close to freezing, it's not unheard of to have snow in October.  Maybe you've already forgotten, but remember last year?  Yep!  First snow fell on October 29, 2011 with a record 0.6" for the day.  The most snow to ever fall in October was way back in 1925 with a whopping 2.2 inches!  The earliest snow recorded in weather records was on October 3, 1892.  My thoughts on snow this October?  Not likely, but that's not to say it can't happen.  It's a little odd seeing snow on trees that have red and yellow leaves still on them.  Weird to see snow on pumpkins, too!

WJLA

Ok, now I feel like I'm getting a head of myself!  Let's get back the "real" fall.  How about fall foliage?  Here's when you can expect to see the leaves changing.

Fall Foliage Timing

Get ready for some fun outdoor events this October, too.  If you're a runner, maybe you're already signed up or know someone participating in the Army 10 miler (October 21) or the Marine Corp Marathon on October 28 (I hear our very own Alex Liggitt is a participant!).  If you're more of a foody, like myself, the "Taste of Bethesda" is on October 6 and the "Taste of D.C." runs from Oct.6 to Oct. 8.  There are so many other fun festivities to partake in across our area, so get out and enjoy all that the season has to offer!

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Fantastic Friday Fog Timelapses (Video)

September 28, 2012 - 11:19 AM
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Fog rolled through portions of the area this morning as you could easily tell by watching Adam Caskey out in Centreville this morning on Good Morning Washington. Fairfax County wasn't the only place to see fog.. There was a Dense Fog Advisory through 10am this morning for Fauquier County in VA and points south and west to the Blue Ridge. Check out some of these awesome timelapses from the National Park Service camera on the Blue Ridge as well as Great Falls (Fairfax Co., VA) and Middletown (Frederick Co., MD) weatherbug cameras.

This was actually radiation fog as we had plenty of moisture at the surface from the showers overnight. When the skies cleared, the temperatures dropped and reached the dew point at the surface creating the layer of fog that finally burned off in the late morning hours.

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Ready or Not, Daylight Getting Shorter Each Day

September 25, 2012 - 04:57 PM
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If you're anything like me, you're welcoming the cooler and more seasonable autumnal air that has settled in over the region, as of late.  The autumnal equinox occurred on Saturday, September 22nd at 10:49am. Until the winter solstice, the North Pole will continue to tilt farther away from the sun.  What does this mean for us, in the Northern Hemisphere?  Well, shorter daylight and cooler temperatures.  So how much daylight will we lose until the winter solstice on December, 21st?  Starting with today, Tuesday, September 25th, we have just about equal parts of daylight and darkness.  By the end of October, we'll have lost about an hour and a half of daylight and by the winter solstice, we'll only have about 9 and a half hours of daylight.

Duration of Daylight in D.C.

I found a neat image of an analemma that gives a great visual of the placement of the sun from the vernal equinox through the autumnal equinox . What's an analemma?  It's a sequence of the sun at the same time of the day at different days of the year.  It looks like a figure eight curve.

Tunç Tezel (TWAN)

This particular image was taken at the same time on 17 different days from April 2nd through September 16, 2012. The highest sun was on June 20, the summer solstice, at the northernmost declination. The two closest to the horizon are near the equinoxes.  You can clearly see the sun's position at different times of the year and how high/low in the sky the sun is in relation to the season. 

If you're not a big fan of the shorter daylight hours, we'll start gaining daylight after December 21st.

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Today was the coldest morning in how long?

September 25, 2012 - 10:35 AM
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Temperatures dipped into the 30s in parts of the ABC7 viewing area earlier this morning (see image), but the temperature remained in the 50s at Reagan National Airport (DCA). Nevertheless, it was the coldest morning since May 12th for DCA, which is 135 days ago.  Another way to look at it: 37% of a year passed before DCA dropped to 53°. The average low today is 59° for DCA.   

Martinsburg, WV bottomed out at 39°, which is their coldest reading since April 29th (148 days). This was 11° below average. Hagerstown and Dulles Airport were more in line with DCA and saw their coolest readings since mid May. 

If you don't like the cooler weather, take comfort in knowing that today was the coolest morning of the foreseeable future was you can expect mornings in the 50s and 60s the rest of the week and through the weekend. However, I say bring on the cold and snow!

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Spectacular Sunrise & Sunset & *Almost 12 Hours of Light & Dark

September 24, 2012 - 11:30 PM
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The first Monday autumnal sunrise of 2012. What a gorgeous sunrise, too! The altocumulus clouds present in the morning made for a colorful sunrise. Take a look!

With a cloud free sky in the evening, the sunset wasn't quite as colorful, but still gorgeous, nonetheless. Take a close look at the timelapse below. I thought the white streaks buzzing through the sky looked like shooting stars. Bob Ryan thought they were UFO's. What do you think they look like?

In case you couldn't figure out what the white flashes in the timelapse are, they are jet contrails. They look a lot different when you put them in fast forward!

A little side note: the equinox occurred on Saturday at 10:49am.  It's a common misconception that there is 12 hours of daylight and darkness on the equinox.  It's close, but not exact.  Here's a more thorough explanation in a recent blog.  Tuesday, Sept. 25th will have equal hours of daylight and darkness.

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Equinox Sunset: Where is west

September 24, 2012 - 01:02 PM
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This is a real quick one.  I was in the beautiful Blue Ridge Saturday evening at sunset.  This was about 6 hours after the Autumn Equinox and these pictures were the sun setting over Skyline Drive.  The sun setting exactly in the west.  Not only in Virginia, but in Maine, Florida and even Brazil.  Not at the same time of course but on Saturday sunset is in the west every place.  Which photo did I take first?  Enjoy

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Number 2 (or is it number 1?)

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Record lows chill Dakotas; D.C. weather fall-like

September 23, 2012 - 07:27 PM
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Autumn arrived on schedule across much of the U.S. this weekend. The equinox rang in at 10:49 a.m. Saturday and Mother Nature decided to chill things off just in time Sunday morning. Now, the cool blast has settled into the nation’s capital but not for too long.

A sprawling Canadian high pressure swooped in behind a cold front to bring record lows to the Dakotas! Check out some of the temperatures from Sunday morning below:

LOWTEMPS

Now, a chunk of that autumn chill is moving into the Ohio Valley. Lows will drop into the 30s and a few areas could see frosty weather tomorrow morning. Locally, temperatures could dip just enough to see the freezing mark briefly in the Allegheny Mountains where a Frost Advisory is in effect for Garrett County.

frost

When is frost most likely during the fall season inside the Capital Beltway?  Well, it won't happen with this cold blast but check out my blog from earlier in the week to find out when it's most likely according to climatology.

Food for thought:
- The last time the temperature dipped to 39 degrees at Reagan Nat’l was March 27th.
- The last time the temperature bottomed out at freezing was March 6th.
- Temperatures didn’t fall below freezing at Reagan National last fall; it took until December 11th.

High pressure builds overhead Monday and Monday night across the Mid-Atlantic. Clear skies and light wind could allow spotty frost to form in suburbs to the west of Washington like Frederick, Front Royal, Purcellville, Sharpsburg and Smithsburg.

Temperatures will warm up a bit by the middle of the week as southerly winds return.

Stay with ABC7 and WTOP Radio for the latest forecast and have a great week!

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Autumnal equinox: Equal Hours of Daylight and Darkness? Or Not?

September 22, 2012 - 09:00 AM
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Wait for it... 10:49am EDT Saturday, September 22, 2012 = autumn in the Northern Hemisphere! 

The equinox occurs when the sun passes directly over the equator.  It can also be understood that the tilt of the Earth's axis is neither away or toward the sun.  This occurs twice a year - on the spring and autumnal equinox.  The word equinox, in Latin, means "equal night", which signifies the equal parts of daylight and darkness.  Take a look at where the Earth is in relation to the sun during both the vernal (spring) and autumnal equinoxes. 

NASA

Since equinox means equal, the hours of daylight and darkness should be equal, right?  Here are the sunrise and sunset time for D.C. on the equinox (Saturday, Sept. 22): Sunrise: 6:56 a.m.  Sunset: 7:04 p.m..  So if there isn't equal parts of daylight and darkness on Saturday, why is it the equinox?  The day we have 12 hours of daylight and 12 hours of darkness actually falls on Tuesday, Sept. 25.  Sunrise: 6:59 a.m.  Sunset: 7:00 p.m.   Shouldn't Tuesday be the autumnal equinox?

Well, we have the atmosphere to thank for this oddity.  Also, the definition of sunrise and sunset.  Sunrise occurs the moment the tip of the sun can be seen on the horizon and sunset is the last minute the sun can be seen before it dips below the horizon.  Also, keep in mind our atmosphere refracts, or bends, light, which makes it appear as if the sun is rising or setting earlier. 

The true equinox occurs when the center of the sun's disk crosses the celestial equator and this occurs at 10:59 a.m. EDT on September 22.  At the same time the equinox occurs in D.C., it occurs across the globe.  As the Northern Hemisphere enters the fall season, losing hours of daylight, the Southern Hemisphere, enters the spring season and gains hours of daylight.  Here's a neat view of the equinox and the solstices from space!

NASA

You won't notice anything striking at the time of the equinox, but just think about the sun passing directly over the equator. Then, after Tuesday, the hours of daylight start getting shorter until the winter solstice.

Happy Equinox!

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D.C. Sunset: Great sunset looking west

September 20, 2012 - 10:26 PM
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A very quick blog, but here is the video of the sunset. Tomorrow, Friday, the sun will set exactly in the west.... but this was colorful.  Enjoy!  Sunset tomorrow is at 7:06pm. 

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Weather Forecasting: How is it done?

September 20, 2012 - 03:50 PM
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Every wonder how we meteorologists do what we do? Or maybe “What the heck are they doing”? Or, I know, “How did they make such a busted forecast”? Well this weekend is your chance to learn all about weather, weather forecasting, meet many meteorologists, ask questions, watch a forecast being made 

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and even watch a weather balloon and instruments being launched.

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It’s all part of the Open House at the local National Weather Service Forecast Office in Sterling, Virginia this Saturday and Sunday. 

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Saturday 9:30 AM – 4 PM and Sunday 12:30 PM-4 PM. Here is the link with all the information. Saturday afternoon you probably will be able to watch meteorologists tracking approaching showers on the new Dual-Pol Doppler radar 

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If you are a student interested in a career in meteorology . . . or a parent with a future meteorologist this is a great opportunity to learn what forecasting is all about. And I’ll be there Saturday morning too.  Hope to see you there.

 

 

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First Frost D.C. : When Will the Growing Season End?

September 20, 2012 - 05:00 AM
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Say it isn’t so… just at the very beginning of the month temperatures were in the middle 90s and now much more refreshing lower 70s are coming down the pike for the latter half of the weekend. The days are getting shorter by the day and the jet stream is dipping farther south as the sun gets lower in the sky. This all equals one thing: Fall!

The big question now before we race into winter is……how much longer will the flowers be in bloom and the grass stay green before the big killing frost hits?

To answer that question, let’s look at what past weather records show for the first frost.

localfrost

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Wild Weather: Big changes in the sky in 24 hours

September 19, 2012 - 04:44 PM
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September usually is a bit more tranquil than the last 24 hours.  Watch the rapidly moving storms moving into Washington from the west Tuesday.

Then look at the beautiful sky today as we had just some high clouds drifting by on much lighter winds.

But our area and the East Coast weren't the only regions recently hit by big storms.  Look at this great visualization from NASA showing a huge storm in August almost moving across the North Pole.  The red arrows are the highest winds.

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A look at the heavy rain and severe weather Tuesday

September 19, 2012 - 12:19 PM
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Not only did the D.C. area have strong storms roll through the region yesterday (Photo Gallery) but also very heavy rainfall. I actually think we lucked out, as if the region had any clearing ahead of those storms, the line itself could have been worse. We could have also seen additional storms develop ahead of the line which would have been bad with the available shear. Lucky for us, it didn't happen.

Storm Reports on Tuesday the 18th

Here is what the region did see. Above is the storm reports from the Storm Prediction Center. You can see the blob of blue directly over the D.C. area, which had numerous reports from the Sterling National Weather Service office. Throughout the day, there were 133 wind damage reports for the United States, most of which from the Mid Atlantic to the Northeast.

Rainfall was even heavier than predicted, with some locations recording over 4 inches of rain. On our WeatherBug Network, Myersville in Frederick County, MD received over 4 inches of rain, Purcellville in Virginia had 2.5, and locations around D.C. saw just over an inch.

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D.C. Sunrise: Great skies after the storm

September 19, 2012 - 11:24 AM
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Adam Caskey had our camera looking over Washington running before sunrise this morning as the clouds from yesterday's wild storms were moving away. 

We're losing over 2 minutes of daylight each day as we get closer to the Autumn Equinox, so enjoy all the sun we have and this great timelapse.

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Severe weather in the D.C. area yesterday our (Live Blog)

September 19, 2012 - 06:40 AM
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LIVE SUPER DOPPLER      Send Pictures to iwitness@wjla.com

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6:13pm: Tornado watch has been canceled for all counties West of the Chesapeake Bay.  The severe threat for the area is over.  Showers will continue through about 9pm, but skies will clear overnight and cooler, drier air will return for tomorrow.

5:27pm: Tornado watch canceled for the entire viewing area with the exception of Calvert and St. Mary's county, which continues through 7pm. 

5:14pm: Severe threat over, but showers, and a few bands of heavy rain, are still possible through the rest of the evening.  Temperatures are already dropping into the 60s.

4:38pm: Check out our Stevensville WeatherBug camera as the line heads over the Chesapeake Bay!

4:24pm: Anne Arundel county under a Severe Thunderstorm Warning until 4:45pm. 

Live Super Doppler

4:15pm: Tornado watch has been canceled for D.C. and counties West.  The Tornado Watch remains in effect through 7pm for Prince George's, Anne Arundel, King George, and couties East.  Here's the latest watch map.  I wouldn't be suprised if the current counties are dropped early.

Tornado Watch until 7PM for counties highlighted in yellow

4:08pm: Here is typically what the D.C. area saw with heavy rain and gusty winds with the line that moved through. This was taken by our own Sam Ford in the Bloomingdale part of D.C. 

Heavy rain in the Bloomingdale part of D.C.

4:01pm: Severe thunderstorm warning for Calvert, Charles, and St. Mary's counties until 5pm.  The line currently extends from Clinton, to Waldorf, and towards La Plata and is moving East at 45mph.  There is still minimal lightning, but expect torrential rain and gusty winds.

Live Super Doppler

3:58pm: Here was a picture taken by Dave Johnson at Dulles Airport of an Air France A380 awaiting the line of storms.

Air France A380 from Dave Johnson

3:50pm: The severe line of storms continues to push east of D.C., though heavy rain is still common through much of the area even west through Loudoun and Clarke Counties. The worst part of the line will affect Charles, Anne Arundel, Calvert and St. Mary's Counties over the next hour to hour and a half. Wind gusts to 60 mph will be possible as well as very heavy rainfall with 2 inch amounts common.

Frederick, MD has received 3.74 inches of rain at Hillcrest ES, Martinsburg picked up 2.03 inches at Rosemont ES and Dale City has seen 1.53 inches so far at Godwin MS. Be careful on your commute home as it is sure to be a wet one!

3:44pm: Severe thunderstorm warning in effect until 4:30pm for Anne Arundel, Calvert, Charles, St. Mary's & King George's counties.  These areas can expect downpours and gusty winds. 

3:35pm:  Tornado warning is canceled for Prince George's and Montgomery counties.  Still expect some heavy rain and gusty winds along the main line of storms that's moving through Prince George's and Anne Arundel county.  More storms building just South of D.C. and South along I95.   

3:26pm:  Latest live doppler in the area where the Tornado Warning has been issued.  No strong indication of rotation; however, there could be a little spin up and with the heavy rain it could be difficult to see.  This line of storms moving very quickly to the NE at 45 mph.

Live Super Doppler

3:16pm: A Tornado Warning is in effect until 3:45pm for Prince Georges and Montgomery Counties. Locations that may be impacted are Chillum, Beltsville and Fairland. It's moving along Rt. 1 and I-95. There is no ground sightings of this tornado, it is radar indicated.  Still seek safety at this time if you are in the path of this cell. 

3:13pm: Here's a picture from Lauren Bevington of the approaching line in Tysons Corner about 20 minutes ago.

Here's a picture from Lauren Bevington in Tysons Corner, VA

3:10pm: Severe thunderstorm warning now extended until 4:15pm for D.C., Arlington, Fairfax, Montgomery, Prince George's, and Anne Arundel counties. Storms are moving quickly to the NE at 15mph.

3:03pm: The line of storms is currently moving through the D.C. Metro and 495 Beltway. It stretches from Rockville and Bethesda south to Lorton and will move over the Potomac into D.C. and Prince Georges County in the next 15 mintues. 

2:55pm: Here's a view of the line from Virginia from Whitney Wild. 

Photo from Newschannel8's Whitney Wild

2:36pm: Strong line now moving into western Fairfax County, Montgomery County and Prince William with damaging wind gusts and heavy rain possible. Watch out Reston, Herndon, Fairfax City and east towards Arlington, Alexandria and D.C. In addition, people around Rockville, Silver Spring, Gaithersburg and Bethesda should stay indoors over the next hour.

2:25pm: Here's a look at the severe line heading towards Fairfax and D.C.

2:16pm: I'm really not liking the look of the line moving into Prince William County in Virginia as it appears to be possibly bowing just a bit. It also looks like it will be heading towards Fairfax, the 66 and 95 corridors, and the D.C. Metro.

The National Weather Service actually just issued a Severe T-Storm Warning for this line that extends through D.C., Fairfax, Prince William and Montgomery Counties until 3:15pm. The line is moving around 50mph and winds may exceed 60mph in this line.

1:53pm: A severe line of storms has developed and is heading east towards the D.C. Metro. The main line is already heading into Loudoun, Montgomery, Fauquier, Prince William and Fairfax Counties. In addition, a Flash Flood Watch is now in effect until 8pm for the majority of the D.C. area.

1:00pm: There have already been a few storm reports today in Loudoun and Clarke Counties in VA. Trees were reported down in Purcellville in Loudoun and Wickliffe and Briggs in Clarke County.

12:51pm: A heavy line of storms will continue to move through Frederick and Loudoun Counties. Here's a view.

12:42pm: There is a line developing from Pennsylvania south into Maryland and Virginia that you can see here on this Mid Atlantic Radar loop. It appears like this line may get to the D.C. Metro as early as 3pm this afternoon. It will definitely accompany damaging wind gusts and very heavy rain so be sure to stay tuned here for further updates.

12:29pm: Speaking of that heavy shower, a Severe T-Storm Warning is in effect until 1:30pm now for the line moving into Northern Loudoun County in VA and Frederick County in MD. Damaging winds in excess of 60mph will be possible in this line as it heads towards the City of Frederick.

12:18pm: Another heavy rain shower with gusty winds will be entering western Loudoun County in VA and southwestern Frederick County in MD. Wind gusts to 40 mph or higher will be possible along with the heavy rainfall.

11:51am: Here's a quick severe weather video update.

11:27am: An upgrade to a Moderate Risk for storms will be coming soon from the Storm Prediction Center. This continues to show just how volatile the atmosphere is today. Be safe! 

11:19am: Severe Thunderstorm Warnings are now in effect for Loudoun and Frederick Counties as this strong line of storms moves east. The most dangerous part of the storm right now is along the Jefferson, Clarke and Loudoun County borders moving northeast around 40 mph. 

10:56am: A Tornado Watch is in effect for the entire D.C. Metro area until 7pm tonight. Be prepared today to take shelter immediately preferably in a basement or a small interior room away from doors and windows.

10:41am: With severe weather imminent for the D.C. area. Know what to do in case of a power outage and what to do with your food in case you lose power for a prolonged period of time.

What to do in case you lose power?

How long will your food last? Food Safety List Here

10:35am: The first Severe Thunderstorm Warning of the day is in effect until 11:15am for much of the Shenandoah Valley. Winds in excess of 60mph will be possible along this line.

10:28am: Here are some of the greatest rainfall totals so far today from our WeatherBug Network:

Wintergreen Mountain: 2.97"      Frostburg, MD: 1.87"      Hagerstown, MD: 1.39"      Martinsburg, WV: 1.29"      Harrisonburg, VA: 1.11"

10:21am: Rainfall potential across the area looks good with up to an inch or two of rain across the area. Flash flooding doesn't seem like a huge threat with the recent stretch of dry weather but could be possible if areas get more rain than anticipated. Below is from one of our in house weather models. Here is what HPC is thinking for today.

Rainfall Potential Today

10:05am: This is what we are thinking as far as threats to the D.C. area today. The highest threat will be damaging winds, with the secondary threat being isolated tornadoes. We will let you know as soon as any watches or warnings are posted.

Main threats for the D.C. area today

10:01am: Check out this WeatherBug camera is storms enter the Raleigh, NC area over the next hour.

9:56am: A Tornado Watch has been issued for Central North Carolina including the Raleigh area until 5pm this afternoon.

9:49am: A Mesoscale Discussion has been posted for our region and south into North Carolina, stating that a Tornado Watch may be needed to be placed in the circled area in the next few hours. The Storm Prediction Center is monitoring our area and will place the region under a watch if necessary.

Mesoscale Discussion Area as of 7:49am

Here's the story. A strong area of low pressure and associated cold front will move through the region today. Ahead of this front, there is a tremendous amount of shear in the atmosphere, which is basically winds changing in speed and direction with height. It is so today that not only will damaging winds be possible, but also the potential for tornadoes. Be sure to stay with this live blog through the rest of the day to know exactly what is going on across the D.C. area.

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Tuesday Severe Weather: The latest risk and timing

September 17, 2012 - 04:45 PM
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10:00PM Update:  No reason to change this.  Risk of severe weather for Tuesday continues.  Damaging winds LATE and will increase risk of small whirlwinds but risk of large tornadoes very low.  The late outlooks from Storm Prediction Center remain the same

Usually when we get into mid-September the chances of severe thunderstorms diminish.  But Tuesday, the combination of a storm and rain moving near us and a strong cold front moving in from the west, will generate a combination of rain and likely strong winds and what is called "shear" in the air above us. 

All likely to combine to bring a high risk of strong and perhaps damaging winds.  Here is how we see the risk of tornadoes, wind, hail and flooding for Tuesday. 

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The National Weather Service Storm Prediction Center has the D.C. area right at the center of a 30 percent probability of severe weather Tuesday.  

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Here is one of the the things that show us the risk of severe weather Tuesday. It's a "model" or simulation of the temperature, moisture and wind profile above us Tuesday afternoon.  

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I've circled the winds near the surface and about 3 miles above us.  You can see the very moist winds from the south at the surface and the indication of winds about 75 mph above us and from the southwest.  

 

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The combination of the change in wind speed with height, and the change in direction is what is wind shear and one of the indications of possible severe weather.  The very latest from some of the ensemble simulations at the Storm Prediction Center also do show a risk of possible small tornadoes because of all the shear or spin in the atmosphere. 

 

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No sign of a big outbreak, but even rotating rain showers can generate a small tornado or whirlwind in our area.  More to come and we will also be live blogging starting Tuesday morning to keep you posted and any severe warnings go out immediately on our @StormWatch7 Twitter account.  We will keep you informed.

 

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Heavy rain possible in D.C. next week

September 14, 2012 - 11:20 AM
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After the past 5 days with complete sunshine and cool temperatures, clouds have finally streamed back into the area today ahead of a cold front. Oddly enough, the past 5 days have been below average at Reagan National Airport. There hasn't been a stretch of 5 days below average since June 3rd through the 7th! That's over 2 months!

As a cold front will move into D.C. overnight, the area will see some rain right? Not exactly.. Typically the D.C. area will see some rain when cold fronts pass overhead, but this one may actually be a dry front as it is a very moisture starved system. Most won't really care about this as long as the weekend is nice, but heavier rain will be back by early next week.

HPC 4-5 Day Precipitation Outlook

Above is the 4 to 5 day quantitative precipitation forecast (QPF) outlook from the Hydrometeorological Prediction Center (yea we just call it HPC). Meteorology can be wordy can't it?? Check out the heavy swath of moisture forecast from the Gulf Coast to the Northeast. Our area should be able to tap into some Gulf moisture with the heaviest threat for rain coming on Tuesday.

As of today's forecast, parts of the D.C. area could receive up to 2 inches or more of rain. We'll be sure to keep you updated on this throughout the weekend and into early next week. Just wanted to give you a heads up so you'll have something to talk about while out on the town this weekend!

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Summer of 2012: Just Hot or Did We Do It?

September 14, 2012 - 10:17 AM
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The recent break in the heat and humidity have sure been welcomed by all of us. This summer (June-August) was another hot, humid DC summer and the 3rd hottest in Washington weather records. In a recent report and data compiled by the National Climatic Data Center, also the 3rd hottest summer in the United States.

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 More evidence of climate change and global warning . . . or just one of those hot summers we get in DC? As I pointed out recently, the urban heat island effect has had a significant impact on the temperature records of Washington, officially recorded at Regan National Airport since the early 1940s. This past summer the temperature at Dulles Airport was almost 4°cooler than at DCA so we have to be careful. Right now here in Washington, we are on a pace to have the warmest year in weather records.  

Both at Washington National and Dulles.  The placement of weather instruments and the changes of of environments around the instruments are important as an AGW critic blogs about. It's important to have critics and critical comments.  But we all, you and myself, the AGW unconvinced, and sure, the climate scientists have to be careful we don't have biased blinder on.  An interesting read on this is Matt Ridley's recent columns in the Wall Street Journal on"confirmation bias".  Here is his third of three columns on this.  All three sure worth a read for all of us.  But, looking at summer and annual temperatures in the DC area and the globe, the trends all point in the same direction. The average temperature is slowly increasing. 

 

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Sure as you can see there are year to year variations and even variations over decades, the slow warming is sure not a smooth upward curve but the trend is clear. The big question is how much of this warming have human footprints. How much is natural and how much is “us”. I don’t think anyone would argue we have NO impact on our environment. Look at this recent TERRA satellite image from 400 miles above us. 

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See any human footprints on the environment?  We sure have changed the land and environment around Washington DC. As a prominent critic of “simple” climate answers, Roger Pielke Sr. argues “The needed focus for the study of climate change and variability is on the regional and local scales. Global and zonally-averaged climate metrics would only be important to the extent that they provide useful information on these space scales.”  But the global "metrics" or footprints are important in that they are showing more and more evidence and confirmation of ideas and projections made years and years ago. Some of the first global projections made decades ago by leading climate scientists such as Warren Washington, forecast more rapid warming and impacts at higher latitudes.  the very latest satellite measurements of sea ice extent in the arctic ocean is now at a record low.  

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Oceans continue to become more acidic as the majority of carbon released in worldwide burning of fossil fuels is absorbed by the oceans but also forms carbonic acid. 

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The evidence continues to mount that we are having an impact on our local, regional, and global environment, weather patterns and climate.  Does that mean next summer even hotter or no snow this winter?  of course not.  there are many strong natural factors, ocean temperature patterns, long term cycles, natural variability still not well understood.  Look at the regional summer temperatures across the United States.  

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 "Third hottest summer in the United States" but not in the Southeast or parts of the Pacific Northwest. So what about next summer?  Look again at the variability of average summer temperatures across the United States.  

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The long term trend is clear, but the year to year variability is also clear.  I deal with probabilities so I'll go out on a limb and say I think it is unlikely next summer in Washington will be our 4th really hot summer in a row.  Then to answer the question in my title.  Did "we" make the past summer as hot as it was?   I think the answer is no . . . but we sure helped make it hotter than average and our footprints of a warmer world, probably a warmer DC area in the coming decades are clearer and clearer all the time.  Some of my colleagues don't agree.  I look forward to their blogs on climate and if there is a human "footprint" on our environment, climate and weather patterns.  Meanwhile enjoy what many folks say is their favorite 3 months of the year.  See our poll and have a great weekend

 

 

 

 

 

 

 

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Atlantic hurricane season now passing peak

September 13, 2012 - 05:00 AM
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Tropical Storm Nadine is the only lone storm churning in the Atlantic here in mid-September. Just like its predecessors Leslie and Michael, it will get deflected away from the East Coast in the coming days.

Nadine

September is historically known for producing the greatest number of tropical cyclones. As a matter of fact, September 10th is the day when over the last 100 years there is the most number of active named storms.

Hurricanepeak

Now that we are past that point, the numbers will likely fall off dramatically. This can be contributed to cooling ocean temperatures as the lower sun angle results in less heating and increasing amounts of upper-level wind shear or higher velocity jet stream winds that move south from the polar region to impede on tropical development.

The prospects for an East Coast landfalling hurricane are diminishing as well. The weather pattern across the lower 48 by the end of September becomes rather progressive. The jet stream dipping south tends to send frequent cold fronts and disturbances across the U.S. into the eastern Atlantic. The upper-level winds tend to deflect storms away from the coast for this reason.

upperchart

We’ve already surpassed the average of named storms that form in a season. That number is 12 and Nadine marks the 14th named storm so far. Isaac has been the only landfalling U.S. hurricane this year, similar to the “I” storm Irene last year. Prior to Irene last year, the last landfalling tropical cyclone was Ike in 2008.

Wondering about other land falling hurricanes prior to Ike? Check out this great NOAA site that shows landfall location, name of the storm and year it happened.

By October, south Florida becomes most at risk for a landfalling hurricane. Florida was hit by 6 of the 8 major hurricanes that hit the U.S. in October between 1900 and 2000. Wilma was the last major hurricane to hit the U.S. in October.

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Neil Armstrong: NASA Coverage of Memorial Service at National Cathedral

September 12, 2012 - 05:40 PM
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The first person to walk on the moon, Neil Armstrong, will be celebrated at the National Cathedral Thursday, September 13th, 2012.

Neil Armstrong - NASA

Armstrong passed away Saturday, August 25, 2012 after complications from cardiovascular procedures at the age of 82.  Armstrong lived a full life with many accomplishments, namely, his work with NASA.  You are probably familiar with Armstrong's famous first words, as he set foot on the moon, "that's one small step for man, one giant leap for mankind". 

Personal Note by Bob Ryan: I was probably one of the few Americans who could not see Neil Armstorng's historic first step onto the moon.  In July 1969, I was working for NASA, but on Barbados of all places.  It was part of one of the first international weather experiments, Project BOMEX, and there was no live satellite television on Barbados.  I listened to the historic moment rebroadcast via short wave and heard that the landing was a success.  The first picture I saw was the cover of Life magazine in a hotel lobby.  I had to wait until I returned to the U.S. a few weeks later to see the TV "replays" of Neil Armstrong's historic first step and he and Buzz Aldrin bounding around the moon.

Armstrong on the Moon - NASA

Neil Armstrong began his NASA career in Ohio and received many awards and special honors throughout his career including the Presidential Medal of Freedom; the Congressional Gold Medal; the Congressional Space Medal of Honor; and the Explorers Club Medal, just to name a few. 

The memorial will be televised on NASA TV at 10am EDT, Thursday, September 13th from the National Cathedral, right here, in Washington, D.C.  The National Cathedral holds a moon rock that the astronauts of Apollo 11, Neil Armstrong, Buzz Aldrin, and Michael Collins, brought back from their mission to the moon.  These astronauts presented the National Cathedral with the moon rock on July 21, 1974, on the five year anniversary of the first lunar landing. 

Washington National Cathedral Space Window

The National Cathedral dedicated a window titled the "Scientists and Technicians Window (Space)".  This window is a special part of the Cathedral's iconography that tells the stories of our nation's history.  According to the National Cathedral, the space window " symbolizes the role of faith in America". 

You can watch special programming from the memorial service through NASA TV - this link will provide you with an online link and where to find the program on cable television.

 

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