From the ABC 7 Weather team

Archive for category Severe Weather September 2014

Roller coaster temperatures this week, strong storms possible Thursday

September 9, 2014 - 08:46 AM
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The weather picture is rather complex this week and we've got a little bit of almost everything in the forecast, even SNOW! (Ok, the snow is for Canada, Montana and maybe the Western High Plains, but now I have your attention!)

Low pressure has been keeping us cloudy and cool in the Mid-Atlantic since Sunday night. The high in D.C. yesterday was 77 degrees and with mid-upper 70s again today, it will be the coolest stretch of temperatures since late May (thanks to Ryan Miller for that nugget). All of this is happening on the average last date of 90 degrees at Reagan National.

 

(This Afternoon)

 

As the low pressure system departs tonight, our focus turns to a potent cold front that is currently in the Midwest.  MUCH cooler air is coming in from Canada behind it where they have been seeing some snow!

 

(GFS Model showing possible snow in Western NE Thursday)

 

The cold front drops through the plains and spreads toward the east. Check out the chilly nights ahead for our friends to the north!

(Flirting with Freezing Thursday AM Midwest)

Notice on that forecast model that as the cool air invades the nation's mid-section, warm air will be drawn in ahead of that front it the east. It will be muggy in D.C. Wednesday as it warms up to around 80 and by Thursday we reach the top of the roller coaster with  highs back in the mid to upper 80s. Here's a look at highs from the North American Model.

 

(NAM Temperatures Thursday)

 

By the time it arrives in the D.C. area, this storm system will already have a history of producing severe weather. Today it will hit the Midwest and then the Great Lakes/Ohio Valley on Wednesday. By the time it reaches us, much of the energy will be to the north. However, with a strong jet in the upper levels of the atmosphere, the thunderstorms that develop over the D.C. region could produce damaging winds Thursday afternoon/evening. 

 

(Storm Prediction Center Severe Outlook Thursday)

 

This all should pass us overnight on Thursday and stall in the southeastern U.S. That puts us in the cool sector with 70s again for highs and overnight lows in the 50s even inside the beltway. The core of the cool air evades us, but it sure will feel like fall. In addition, a reinforcing cold front comes in on Saturday (bottom of roller coaster) with a few showers. Expect below average temperatures into next week.

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Strong Storms Likely Saturday

September 5, 2014 - 08:19 PM
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It says September on the calendar, but it certainly doesn't feel like meteorological fall.  Temperatures have started out well above average for the first few days of the month, but big time changes are on the way!

A strong cold front is currently moving through the Midwest.  Ahead of the front, very hot and humid conditions exist.  Behind the front, much cooler and drier air.

Strong storms have been firing up along the front all day.  Tomorrow, as the front approaches the east coast, scattered strong and severe thunderstorms will develop.  It'll feel like summer tomorrow afternoon with highs back into the lower 90s, but feeling like the upper 90s with very high humidity.  The heat and humidity, combined with the approaching front, will trigger strong to possibly severe thunderstorms.  The greatest threat from the storms will be damaging winds.  As far as the timing, storms could pop anytime after 2pm.  Here's one simulation at 2pm showing a few storms firing up.

WeatherBell - NAM 2pm

A few other simulations suggest the storms will arrive after 6pm.  Check out our in-house computer model that shows widely scattered showers and storms around at 9pm.

Since it will be so hot and humid, you'll want to keep an eye to the sky for ominous looking clouds.  Storms could fire up at any time.  If you're planning on being outdoors, make sure you have the StormWatch weather app downloaded to your phone for radar updates, as well as dangerous storm warning alerts based on your location.  The greatest risk for storms will be between 2pm and 10pm Saturday.

The rain should wrap up overnight Saturday from NW to SE, as the drier air slowly filters in.  Humidity levels will be noticeably lower Sunday with highs around 80 degrees.  Check out a comparison of dewpoint temperatures (measure of humidity/moisture) Saturday and Sunday.

WeatherBell - EURO 2pm Saturday dewpoint temperature
WEatherBell - EURO 2pm Sunday dewpoint temperature

Saturday afternoon dewpoints will be in the lower 70s compared to upper 40 lower 50 degree dewpoint temperatures by Sunday afternoon. 

The front will stall off the coast Sunday and will keep temperatures slightly below average for the early part of next week.  We'll have to watch the front closely because an area of low pressure may develop along the front and could bring a few showers by Tuesday.  It's still too early to tell, but one thing is certain -- cooler and drier, more September-like, weather will return by the end of the weekend! 

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StormWatch 7 blog: Daylight disappearing quickly in D.C.

September 4, 2014 - 10:45 AM
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I've been talking to a lot of people lately that have noticed just how quickly the D.C. area has been losing daylight. In August alone, the area lost over an hour of daylight, from fourteen hours and ten minutes on the 1st all the way back to thirteen hours and four minutes on the 31st. Take a look at the graphic below, which will give you a good idea of the big milestones coming up.

(Duration of Daylight in D.C.)

So far D.C. has lost two hours of daylight since the solstice, but that will jump to over three hours lost by the end of September. Unfortunately the area will be below twelve hours of daylight by then as well. We'll have to wait until October 20th for eleven hours of daylight, and November 17th for ten hours of daylight.

To find the duration of daylight for D.C. or anywhere in the U.S., go to this site here and go to form A, or look around the world in form B.

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Lapse of the thunderstorms moving through Frederick, MD Tuesday

September 2, 2014 - 06:18 PM
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After seeing the potent line of storms form west of the mountains moving east towards D.C., we quickly scrambled to get all of the necessary information out before clicking a few buttons to record a time lapse! Check it out here.

Did you happen to see it? If you did and took any pictures or video, feel free to share them to our Stormwatch 7 Facebook page!

Here is a great picture sent in from Renee Rohwer from Mount Airy, MD this afternoon.

Shelf Cloud in Mt. Airy, MD from Renee Rohwer

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Severe Thunderstorm Watch until 10pm Tuesday

September 2, 2014 - 04:49 PM
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Numerous thunderstorms have developed across the region and some of them have become strong to severe. This prompted the Storm Prediction Center and National Weather Service to post a Severe Thunderstorm Watch for the D.C. Metro and points north until 10pm.

Severe Thunderstorm Watch until 10pm

Storms will have the potential for damaging wind, large hail, heavy rain and frequent lightning. Stay tuned to ABC 7 News for the latest updates and please follow @SteveRudinABC7, @alexliggitt and @DevonLucie for updates on twitter.

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