From the ABC 7 Weather team

Archive for July 2014

Rain back in the forecast for the beginning of August

July 31, 2014 - 04:33 PM

The past few days have been just about perfect as far as the end of July is concerned. Low humidity levels and below average temperatures have made for very comfortable conditions. One thing has been missing now for a while through the majority of the D.C. area... rain.

Taking a look at some of the area climate reports, you wouldn't think the region has been hurting for precipitation. Reagan National has recorded over 4.5 inches of rain for the month of July. Even the drought monitor shows our area is doing well for precipitation. But taking a closer look, the area has been dry for the second half of the month.

Since July 16, Reagan National has only recorded 0.11" of rain, Dulles 0.13" of rain, and BWI Marshall has seen the most at 0.23" of rain. With the pattern changing as we speak, this should change over the next few days.

WPC Precipitation Outlook through Sunday evening

A frontal boundary south of the D.C. area is expected to push north along the east coast, which will help become the focus for showers and a few storms to ride along. The heaviest rain is expected to remain south and east of D.C., with upwards of 4 inches of rain possible over eastern portions of North Carolina and over 2 inches possible towards the Delmarva Peninsula.


Don't expect the weekend to be a complete washout just yet. Not all modeling is in agreement, but as of now, the highest likelihood for steady rain appears to be Friday night into Saturday morning.

Breaks in the overcast will be likely Saturday afternoon and through the day on Sunday. Temperatures will remain slightly below the average of 88 this weekend with highs only expected to reach the low to mid 80s.

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Record low this morning, but was it a chilly July?

July 30, 2014 - 08:22 AM

The debate around town this morning has been about the best way to describe this morning's temperatures. Would you call it cool? Chilly? Crisp? Pleasant? Perfect? Well, if you live around Dulles Airport, you could call it record-breaking cold. The temperature briefly dipped to 48 degrees.


(Dulles Temperatures and Dewpoint this Morning)


Here's a look at morning low temperatures across the area.


(Morning Lows)


The old record at Dulles for July 30 was 51 degrees, set in 1981. The unusually chilly temperatures also managed to break the July 29 record, dipping below the previous mark at 11:58 p.m. Tuesday night. National Airport bottomed out above its record low of 56. Martinsburg, W.Va., hit a record low and Baltimore broke its record low with 55 degrees. 


(Records at Dulles)

So why has this fall-like weather made a mid-summer appearance? A trough in the upper atmosphere has drawn in cooler air from the north into the Mid-Atlantic. It has made it's way unusually far south for this time of the year. Many records were broken in the East.


(Preliminary Record Lows via


Typically, high temperatures are in the upper 80s in late July in D.C. While we will gradually see temperatures warm up today and tomorrow, the overall pattern keeps us cool to near average through mid-August.

(6 to 10 day Temperature Outlook NOAA)

If you're thinking to yourself that this is a cool July, you're right. As of this morning, Dulles has averaged 74.7 degrees this month, about two degrees cooler than normal. At Reagan National, the average temperature is a bit warmer at 79.8 degrees, right about average. Still, this July is the coolest we've enjoyed since 2009. There were nine days of 90 degree or higher temperatures at National Airport this month, including a high of 99 on July 2nd.  At Dulles, there were just five 90 degree days this month.

If we look ahead to August, climatologically speaking, we will start the month with an average high of 88 degrees and end it with an average high of 84. August is the last meteorological month of summer, with slightly fewer minutes of daylight.

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Haze in D.C. today most likely smoke from Canadian wildfires

July 29, 2014 - 11:45 AM

What a beautiful morning it has been, with lows in the 50s and 60s across the region, including a record-tying low of 59 degrees at BWI Marshall. With such low humidity levels across the region though, you would expect to see deep blue colored skies with now a few white puffy cumulus clouds. Instead, a haze has settled in over the region.

Visible satellite image after 11am

Take a look at the visible satellite image above. Just by looking at this image by itself without motion, it is very hard to see anything that may signify smoke over the D.C. area. But click here to see the satellite in motion. Did you happen to see the very light colored area over D.C. right after sunrise? This is showing the possibility of either some extremely thin clouds, or more than likely, a very thin layer of smoke in the atmosphere.

Courtesy: NASA MODIS

A number of fires have not only been burning in the Pacific Northwest, but also well north of the border in the Northwest Territories of Canada. Above is a look at the NASA MODIS satellite world view which I stumbled upon while perusing the web. I circled the regions of smoke that were showing up yesterday in Northern Canada and over the Hudson Bay. Given the flow of the atmosphere, much of the smoke more than likely was pushed south and eventually southeast into the Midwestern U.S., Northeast and Mid Atlantic States.

Water Vapor Imagery Tuesday Morning the 29th

The upper-level flow shows a large trough through the eastern part of the U.S. and a large ridge over the western U.S. The resulting steering flow has been from Northern Canada southeast through the Midwestern States and directly into the D.C. area. Check out the water vapor loop here. Keep in mind the orange, black and dark grey show very dry air while the purple, blue and white areas show increased levels of atmospheric moisture.

The effects from smoke in the D.C. area will be minimal and air quality is still expected to be good through the next few days, though the haze may hang around tomorrow and Thursday.

NASA MODIS image from July 23rd

The fires have burned over two million acres of land in the Northwest Territories and are thought to have been caused by lightning.

Photos of the fires near Yellowknife, Canada.

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Cooler and comfortable end to July

July 26, 2014 - 06:00 AM

After a hot start to July with eight of the first fourteen days above 90 degrees, the pattern shifted. Since then, high temperatures topped out in the low to mid 80s seven times and reached 90 degrees only once.

Looking ahead to the end of July and the beginning of August, temperatures are still expected to be cooler than normal. Once we get through the weekend, which will feature more heat, humidity, and the chance for showers and the possibility of severe storms, cooler air is forecast to filter in next week.

500mb vorticity plot for next Tuesday

While a large ridge is expected to continue to build over the southwestern U.S., a potent shortwave will move through the Midwest and into the Northeast this weekend bringing the potential for severe storms.

This shortwave will spin around an area of low pressure centered over the eastern part of the Hudson Bay in Canada (above), which looks like it will be blocked from moving anywhere as high pressure sets up east over Canadian Maritimes and the northern Atlantic.

6 to 10 day temperature outlook from the CPC

In reality, what does this mean for the D.C. area? Temperatures may only approach the 80 degree mark Tuesday and low to mid 80s Wednesday through Friday of next week. In addition, humidity levels should be low, with dew points in the 50s expected Tuesday through Thursday before more moisture slides back into the region Friday.

Tuesday afternoon 2-meter temperature anomalies (Credit: WeatherBell Models)

With record heat dominating the headlines, including the hottest global June on record per NOAA, this will most certainly be enjoyed throughout the eastern half of the U.S. next week. Portions of the eastern U.S. will enjoy afternoon temperatures 10 to possibly 20 degrees below the seasonal average.

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Severe Storms Possible Sunday and Monday

July 25, 2014 - 03:07 PM

Say goodbye to the beautiful weather of Friday and hello again to summer in Washington, D.C. for the weekend. That means a return of heat and humidity as well as a return of summertime thunderstorms. Saturday will feature very warm temperatures, right around 90 degrees for a daytime high with increasing clouds and increasing humidity late in the day. Another thing that will increase on Saturday will be the chances of showers and thunderstorms. Albeit, it is only a slight chance of showers and thunderstorms through the PM and overnight hours on Saturday, but still a chance.

An upper level piece of energy will approach the region on Saturday night. Mainly our western areas will be the breeding ground for any action, but by Sunday, we all have equal chances to see showers and thunderstorms across the area as that disturbance passes through the D.C. area.



Also what we are watching after Sunday’s disturbance is a very strong cold front will be dropping out of the upper Midwest and down into the region for Monday. Therefore, we have a chance of showers and thunderstorms Saturday night – Monday, some of which could be strong to severe.
Above graphic, at the top, shows the slight risk area for severe weather Saturday through Monday. The risk moves from the Ohio Valley Saturday to our area on Sunday and Monday. On the bottom of the graphic, the surface features show an area of high pressure overhead bringing us very pleasant on conditions on Friday. Then through 8 p.m. Saturday, the area of high pressure scoots off the coast giving us a southerly flow bringing humid air from the south and transporting it right here into the D.C. area as a warm front approaches the region. By Sunday and Monday morning, the strong cold front is still to the north and west of the area.

So now that we know what is going on, what can we except through the weekend? Well considering that warm front is just to the south on Saturday night, lift from warm advection around the warm front and the piece of energy approaching us from westerly flow aloft will give us that about a 20% chance of storms on Saturday afternoon and evening continuing through the overnight hours. There will be a good chance of severe weather across our area through the day on Sunday as that disturbance moves through the region. One thing that still remains a question is temperatures on Sunday. Right now I have temperatures fairly warm, nearing 90 degrees. But, if we get some thunderstorms in the morning hours, that could down our temperatures for the afternoon and lessen the instability in the atmosphere. Either way, it will still be very muggy outside through the day on Sunday with mainly clouds hanging around. Some of our models do suggest that we get some thunderstorms during the first part of the day on Sunday.




Caption: Showers and thunderstorms around the region weaken slightly as they travel to our area from the north and west. This is around 11a.m. on Sunday.

We do know that any of these storms could produce damaging winds, possible hail and heavy rain. There will certainly be substantial moisture around the region given the nice southerly flow, therefore localized flash flooding is definitely a concern. Take a look at our precipitable water values:




You may have heard this term or “PWATS” quite a bit this summer. Really what preciptable water values are are the amount of water within a vertical column above the surface if it were all precipitated out. These values are over 2.00” in some spots and when we see that, we know there is enough moisture available to create flooding conditions.

By Monday, the chance of showers and storms remains through the day as the cold front finally travels through the region. Again, some of there could be strong to severe but by Tuesday, we are in for another treat.


A nice refreshing airmass moves into the region bringing low humidity and refreshing temperatures. Daytime highs on Tuesday are in the upper 70s to lower 80s! We just got to make it through some summertime storms to get the reward by mid-next week!

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Cherrystone tornado rated EF-1

July 25, 2014 - 11:46 AM

The National Weather Service office in Wakefield, VA surveyed the damage from yesterday morning's storm in Northhampton County in southeastern Virginia and determined the damage was due to a tornado, straight line wind, and a large swath of hail.

Path of the tornado, straight line wind and large hail

Above is a look at the path of the tornado, wind and large hail. The tornado originated in the Chesapeake Bay as the storm rapidly intensified. The EF-1 tornado had estimated maximum wind speeds of 80 to 100 mph and was on the ground for 8 miles over a span of 15 minutes. It's maximum width was 150 yards. The tornado wasn't the only feature that caused damage in this storm.

A downburst resulting in straight line winds was observed in the yellow wind damage swath. Wind speeds were estimated between 65 and 75 mph and downed numerous trees and even contributed to overturning several camping trailers in the Cherrystone Campground.

The hail core fell mainly within the blue lines (first image above) in the size of golfballs to a few reports of baseball size. This caused considerable tree and leaf debris, crop damage and siding damage on homes in the path.

The storm caused 36 injuries and 2 fatalities.

See the rest of the preliminary storm survey here.

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Average hottest days in D.C. in the rearview, daylight diminishes

July 23, 2014 - 12:18 PM

With temperatures forecast to be in the low to mid 90s, one wouldn't think the average hottest days are behind us, but the average high drops to 88 today. Don't worry, cold air isn't exactly going to march right into the D.C. area, as the average high temperature remains in the mid to upper 80s through the month of August. August also averages nearly 10 90-degree days, something we haven't seen too much of this year.

90 degree days in D.C.

In fact, D.C. is actually below average for 90-degree days so far this summer, with only 15 this year. Compare that to last year, which recorded 21 by the same time. Typically there are around 36 90-degree days per year in the D.C. area, so it appears this summer may go down as below average in that category. Ninety-degree days or not, this summer has still been above average, with temperature departures of +2°F in June and +0.5°F so far in July. We'll see how August fares.

Looking ahead, the heat will briefly subside Thursday and Friday but will return for the weekend. Highs should top out in the 90s both Saturday and Sunday, prior to a big-time cool down next Tuesday through the end of the month. Highs may only reach the 80-degree mark next Tuesday!

Duration of daylight for D.C.

Daylight continues to diminish since the summer Solstice, with 28 minutes gone in just a month's time. An additional 14 minutes of daylight will be lost by the end of the month, and over an hour more will be lost by the end of August, so enjoy it while it's here.

While this may be a depressing blog post for some, after summer, there's always cooler and crisp days, fall colors, the Nats playing in October, the Skins taking the field, and plenty of other great things to look forward to. Here's to a fantastic last 39 days of meteorological summer to go!

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45th Anniversary of Landing on the Moon

July 20, 2014 - 05:00 AM

"One small step for man, one giant leap for mankind".  These are the words Neil Armstrong said 45 years ago today after he stepped onto the surface of the moon.

Astronauts Neil Armstrong, Buzz Aldrin, and Michael Collins were all aboard the infamous Apollo 11 flight to the moon.


The three launched into space aboard Apollo 11 on July 16, 1969 via the Saturn V rocket at the Kennedy Space Center in Florida.  Armstrong and Aldrin then climbed into the lunar module Eagle (below) that would descend onto the moon, while Collins orbited in command module Columbia.


At 4:18pm EDT, Armstrong connected with mission control in Houston saying "Houston, Tranquility base here.  The Eagle has landed". 

At 10:56 pm EST, Armstrong set foot onto the surface of the moon.  You can see in the image below the American flag the astronauts planted on the lunar surface.


Buzz Aldrin then joined Armstrong on the moon and the two spent time deploying instruments that would be used for experiments, gathering samples of lunar soil, and taking pictures. 

Here's a great "Moonwalk Montage" that takes us back to that day:


The three astronauts accomplished something the Russians had not.  NASA states they did not want to focus on the "victory" of the mission, but rather emphasized the "peaceful lunar landing by the United States. 

The patch designed for the mission was created by Michael Collins.  On the patch, the American Bald Eagle is depicted landing on the lunar surface, delivering an olive branch of peace.   The words "Apollo 11" were chosen for the top of the patch above a distance crescent shaped Earth.


The United State's determination in exploration through the Space program has taken us to the point where we now have a rover on Mars.  The mission 45 years ago today reemphasizes the spirit of our country and the desire to explore and discover outer space.

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Severe Storms Likely Monday and Tuesday

July 13, 2014 - 06:39 PM

We've reached the climatological hottest time of the year in D.C. with our average high now 89°.  Some big changes on the horizon, as a strong cold front approaches the area.  This cold front will bring a welcome drop in the heat and humidity by Wednesday, but it will come with the price of severe weather for Monday and Tuesday.

Ahead of the front, our airmass remains very hot and humid.  Forecast high temperatures Monday are in the low to mid 90s.  Factor in the humidity and it will feel closer to the 100 degree mark.

The cold front will slide farther east Monday increasing the atmospheric dynamics for severe weather.  Take a look at the surface features, as of Sunday night.

The viewing area will remain under the very warm and moisture laden air until the cold front passes late Tuesday night.  That will help fuel the fire for the strong and severe storms.  The Storm Prediction Center has the entire vewing area (shaded in yellow in the image below) under a 'Slight' risk for severe storms Monday.   This means damaging winds (60+mph), large hail, and isolated tornadoes will be possible with any storms that develop.

Storm Prediction Center

A big dip in the jet stream will allow temperatures and humidity to drop off significantly by Wednesday and the rest of the week.  The clash of airmasses; however, is what is causing this elevated risk for severe weather.  Check out an upper level map (500mb level) that clearly shows the large trough digging into the area.  The brighter colors indicate higher wind speeds, which leads to increased wind shear.  Wind shear can cause damaging wind gusts and tornadoes.

WeatherBell - European Model 500mb heights and wind speed/direction

As mentioned, behind the front much cooler and drier air.  Take a look at the difference in forecast dewpoint temperatures on Monday and Wednesday.  Dewpoints will go from the mid 70s Monday afternoon to the low 50s Wednesday.  You will certainly feel the difference by midweek.

WeatherBell ECMWF Dewpoint Temperature Monday
WeatherBell ECMWF Dewpoint Temperature Wednesday

Remember to stay updated with the StormWatch7 weather team for the latest weather updates.  We also encourage you to download the free StormWatch7 weather app.  You'll have access to Live Super Doppler within the app, so you can track storms on the go.

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Cooler Air, but Not Cold Air Infiltrating the D.C. Area Next Week

July 12, 2014 - 05:10 PM

Once we get through the possibility of severe storms on Monday and Tuesday, cooler air will move right into our region for the end of next week.

Classification. Yes, we are a society that likes to name things: Snowmaggedon, Commutergedon, SnowGuinness, etc. Where a squall line is a “derecho” and where a spill of cold air from the north is coined the “polar vortex.” I get it. I really do. Classification of tornadoes or hurricanes is absolutely necessary, however, to call every snowstorm a “blizzard” just makes me shake my head-but then move on with my life.

Before 2012, we had NEVER heard of the term “derecho” and now it seems every storm that comes through during the summer is classified as that. Before last winter, we NEVER EVER heard the term “polar vortex” used before and now, several months later, we gravitate right to it.

It is all in the eye of the beholder and left up to interpretation amongst professionals in the meteorology field. Although I didn’t want to touch this subject with a ten foot pole, I feel that we are forced to say something. The storm on Tuesday night left so many people wondering whether a “derecho” in fact hit the area that we had to reach out to the Storm Prediction Center to include their thoughts. So now onto the “polar vortex” or let’s just say the “unusual pattern setting up for Mid-July.”

All in all, we do know that next week unseasonably cold air will migrate out of the north and into the United States, spreading out into the Mid Atlantic. There is so much misuse of several weather terms throughout the year that I thought we should revisit the term “polar vortex”.

Our friends at the National Weather Service in New York made this graphic after the hysteria in social media yesterday about “the return of the polar vortex.” They reminded everybody on their Facebook page that “the most basic definition for “polar vortex” is that it is a piece of energy that comes from the polar region. It is generated by the large difference in temperature between the tropics and the poles. The temperature gradient is strongest during the winter; therefore it is more likely to affect mid-latitudes (our area) in the winter. However, it can affect us in the summer, but it is not nearly as strong as it is in the winter.”


There are differing opinions in the meteorology field on whether this is a “true polar vortex’ and that is why you will see so many different articles ALL OVER the internet on whether this is or it is not. This is what the Weather Prediction Center put out yesterday:\


Great. So in the grand scheme of things I ask myself “does it really matter to the general public what we coin this?” The answer I give myself is “no”.
So here is what we know. We have some unseasonably cold air coming down from the north and spilling into the region. The Midwest will get the brunt of the cold weather where temperatures could be as much as 20-25 degrees below normal! That is very impressive for summertime climate. Our normal temperature in the D.C. area for this time of year is a warm 89 degrees. The Climate Prediction Center has given us about a 40%-50 of seeing below normal temperatures next week.

Climate Prediction Center

Now, I got to tell you, if you are expecting temperatures in the 50s/60s then you have to travel to the north and west of here. Temperatures next week (starting Wednesday) are going to fall below normal but we are still talking 70s/80s. Here is a look at our 7-day forecast:

However, before we even get to that cooler air moving in, as you notice on the 7-day we are heating up! Temperatures on Sunday, Monday and Tuesday will have no problem reaching into the 90s. With the added July humidity, we are talking about heat indicies approaching 100 degrees all with the added threat of severe weather each day. The Storm Prediction Center has ALREADY outlined us in an area for a shot at severe weather on Monday into Tuesday:

Storm Prediction Center

So all in all, are we cooling down slightly for the end of next week? Yes. Are we going to have to deal with heat and humidity and severe storms at the beginning of next week? Yes. It is going to be a roller coaster week and we will certainly welcome the cooler air by the end of next week, not matter what we want to call it.

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Full "Supermoon" Tonight

July 11, 2014 - 09:42 AM

It's that time of the lunar calendar where we approach full moon status.  The moon will be full tomorrow morning at 7:25am.  But even tonight, expect a 14% bigger and 30% brighter full moon than full moons of 2013.  The reason?

The moon is in perigee.  The terms perigee and apogee refer to the distance of the moon from the earth.  During perigee the moon is closest to Earth.  The opposite is true when the moon is at apogee. 


Tonight's full moon will be the first of three supermoons this year.  The next will occur on August 10th and the final on September 9th.  The full moon tonight will be less than 224,851 miles away from Earth.  To put that in perspective, at apogee the moon is roughly 252,000 miles away from Earth.  Here's a photograph of the two full moons overlayed on one another. 


The July full moon is referred to as the "Buck" or "Thunder" moon.  The buck moon came from deer's antlers pushing out of their forehead.  The moon is also referred to as the thunder moon because July is the most common month for thunderstorms.


Weather conditions for supermoon-viewing will fairly good. Aside from a few scattered clouds, the sky should feature the bright moon rising at 6:46pm tonight and setting at 5:02am tomorrow morning. If you take some moon pictures, we'd love to see and share them! Happy moon viewing!

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Flash Flood Watch for the D.C. area until Midnight

July 10, 2014 - 03:48 PM


A Flash Flood Watch is in effect through Midnight tonight for the majority of the D.C. area. Showers and storms along a frontal boundary are moving extremely slow, allowing for a prolonged period of heavy rainfall. Baltimore experienced its own storm earlier today which dropped a radar estimated 2.5 inches of rain. Additional storms may do the same for parts of the D.C. area through tonight.

Flash Flood Watch in effect until Midnight

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Rocket Launch from Wallops on Saturday

July 10, 2014 - 07:04 AM

First it was engine trouble and then thunderstorms delaying the launch of an unmanned commercial rocket that will resupply the International Space Station.  As of today, all signs point to a "go" for the Cygnus Rocket launch at 1:14p.m. on Saturday at Wallops Flight Facility in Virginia. The rocket was rolled out onto the pad this morning at Wallops as shown here in a tweet by NASA.

Antares Rocket on the Launch Pad at Wallops Flight Facility

 The rocket will be carrying 3,300 pounds of supplies for the ISS, including food, science experiments to expand the research capability of the space station's Expedition 40 crew members, and tools.  Many student experiments will be on board as well.  This is the second of eight scheduled rocket launches for Orbital Sciences, a private company based in Virginia that has a contract with NASA for the resupply  missions.

Orbital Sciences

 Although the launch will take place in the daylight hours, the burn off from the rocket may still be bright enough to see, even here in Washington, D.C.  Weather looks cooperative with partly cloudy skies forecast. You need to look at about 5 degrees above the  horizon in the southeastern sky about a minute or two after the launch.  Here is a map where it would be visible.


visibility of launch expected from Orbital Sciences

 You can also watch it live on NASA TV starting at 12:30p.m. ET.  If the launch happens on time, it will reach the International Space Station on Tuesday, July 15th. 


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Storms possible through this evening in the D.C. area

July 9, 2014 - 03:35 PM


A Severe Thunderstorm Watch has been posted for much of the D.C. area until 10pm. This comes out after the Storm Prediction Center stated a watch would be unlikely for the D.C. area about an hour ago. After a few storms exhibited damaging winds, it appears they've changed their minds and decided to post one for the region through this evening and early tonight!

Severe T-Storm Watch until 10pm

Showers and thunderstorms will continue to be possible through the afternoon and evening, so please listen for the latest on where they are located and be sure to check Live Doppler Radar before going outside.

Storms will have the potential for heavy rainfall, frequent lightning and gusty winds. We will cover them live on ABC 7 News at 5pm and 6pm.

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Severe Thunderstorm Watch in the D.C. area Tuesday

July 8, 2014 - 07:06 PM

As expected, a Severe Thunderstorm Watch has now been expanded to include the entire ABC 7 News viewing area until 11:00 p.m. Storms will likely bring periods of heavy rain, gusty winds and small hail. Wind gusts may exceed 70 miles per hour in some storms.The watch for western Maryland will expire at 8:00 pm. For the counties included, click here. Stay with ABC 7 News for additional update.


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July Weather in D.C.: Hot, Humid & Stormy

July 6, 2014 - 06:09 PM

The mercury will soar into the 90s while heat indices climb close to 100 degrees early next week. In the meantime, a cold front will likely ram into this heat and humidity, triggering midweek thunderstorms once again.

Downpours and gusty winds are likely with the first round that breaks the heat spell either late Tuesday evening or Wednesday afternoon. This pattern is all too common across the Washington metro area.

Analyzing past weather trends since 1980, July tops the list for the most combined hail, wind and tornado events in the region (see table below).

July Climatology

The biggest threat from any single thunderstorm in July is wind gusts. In order to qualify as a severe thunderstorm, gusts must at least reach 58 mph. July also ranks #1 for the most tornadoes area-wide. On average, there are 6 tornadoes in the region (the western Maryland panhandle into the Shenandoah Valley, northern Virginia, the District and all the way to the Chesapeake Bay) during the month of July.

Notice the breakdown of severe weather reports per hour on any given day. Hail, gusty winds and tornadoes are most common at 6 p.m. (22 UTC = 6 p.m. between daylight saving time (in early March) and standard time (in early November). This makes sense given the atmosphere is generally most unstable late on a summer's day after the sun has been warming the ground all day.

Hourly Severe Climatology

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Arthur Update and Fireworks Forecast

July 4, 2014 - 09:05 AM

Hurricane Arthur has put a damper on numerous firework's displays with many locations having to postpone or cancel.  Fortunately for us, the fireworks should be able to get off without a hitch in the Nation's Capital.  Here's a list of cities where fireworks have been rescheduled.

Hurricane Arthur made landfall near Beaufort, N.C. around 11:15 p.m. Thursday night.  Arthur was downgraded to a category 1 hurricane with winds at 90 mph as of the 9 a.m. update from the National Hurricane Center.  The storm has moved off the coast of the Outer Banks, NC and is quickly moving northeast.
(National Hurricane Center)
As a cold front slides through our area and Arthur moves farther out to sea, skies will clear from west to east, as drier air filters in.  It'll also be quite breezy, with winds gusting to around 30 mph through the day.
Winds will subside by the time the fireworks are set to go off downtown at 9:10pm.  And we couldn't ask for a more pleasant fireworks forecast.  It will be very comfortable, with low humidity and still just a bit breezy.  Click here for a full list of Fourth of July parades, events, and fireworks' displays.
The rest of the holiday weekend looks fantastic!  The humidity will remain low with plenty of sunshine and seasonable temperatures.

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Severe Thunderstorm Watch until 9 p.m. Thursday

July 3, 2014 - 01:24 PM


A Severe Thunderstorm Watch is in effect for the majority of the D.C. area until 9 p.m. tonight. Storms will continue to develop mainly southwest of D.C. and move into the region closer to the evening rush around 5 p.m. to 6 p.m. Very heavy rainfall will be possible in storms, which is why the National Weather Service also put the entire area under a Flash Flood Watch. Be sure not to cross any flooded roadways.

(Severe Thunderstorm Watch until 9 p.m.)

Storms will linger through late this evening but should diminish overnight. A few showers will be possible through the morning hours as the front continues to move through the region and Hurricane Arthur approaches from the south.

Find the latest on Hurricane Arthur here.

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Hurricane Arthur: First Hurricane of the Atlantic Season

July 3, 2014 - 06:14 AM

As of the 8am update from the National Hurricane Center,  Arthur is now a Category 1 hurricane with max winds of 80 mph and moving north/northeast at 8 mph.  Check out the storm via satellite and radar.   

Intellicast Radar

The storm is currently bringing rain to eastern South Carolina and is expected to pass over eastern NC later tonight.   Mandatory evacuations are already in place for Hatteras Island, NC.   Hurricane warnings are in effect for these areas, as heavy rain, gusty winds, coastal flooding, and dangerous surf are expected. 

NWS Morehead City, NC

Arthur is projected to brush the Carolina coast tonight and be off the mid-Atlantic coast by midday tomorrow.  Check out the latest track map from the National Hurricane Center.

National Hurricane Center.

Our local impact from Arthur will occur today.  As a cold front approaches from the west, and tropical moisture from Arthur feeds into our area, severe storms and flash flooding will be possible this afternoon and evening.  The Storm Prediction Center has our area in an elevated risk for severe storms with damaging winds.  The National Weather Service has also issued a flash flood watch for later today, as well.

Storm Prediction Center
NWS Sterling, VA

The cold front will slide east tomorrow morning and help push Arthur farther out to sea.  Drier air will slide in from west to east through the day tomorrow.  It should be rather delightful for the fireworks displays tomorrow evening with low humidity, comfortable temperatures, and a nice breeze.

The rest of the holiday weekend forecast looks great.   Have fun and be safe!


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Tropical Storm Arthur: Forecast Track

July 2, 2014 - 05:30 PM

Tropical Storm Arthur as of 5 p.m. Wednesday has maximum sustained winds of 70 mph and is moving slowly to the north around 7 mph. It is currently centered around 220 miles south-southeast of Charleston, South Carolina. .

Arthur is encountering some upper-level dry air north and west of the center but conditions are still favorable for intensification in the next 24 hours or so. The forecast continues to show Arthur as a Category 1 hurricane with winds around 85 mph by the time it approaches the Outer Banks of North Carolina.

The storm is expected to continue to the north today before a slight turn to the northeast into Thursday morning. As it approaches the Outer Banks and Mid Atlantic, the system will start to push farther northeast into the Atlantic as it encounters the frontal boundary which will move into our area today and tomorrow. This will be the feature that you can thank for hopefully making for a dry 4th of July fireworks display.

8am NHC forecast track update

For Friday, expect cloudy skies, breezy winds and possible showers in the morning hours in the D.C. area. The best chance for rain will be east of the city. Conditions should improve by the afternoon, with a little bit of clearing and diminishing breezes. Temperatures will be more comfortable in the mid 80s and humidity levels will fall with dewpoints back in the low 60s and upper 50s. Not like our typical 4th of July!

WPC QPF forecast for this morning through Saturday morning

If you are heading to the beaches, including the Delmarva, heavier rainfall is more likely along with high surf and gusty winds. Thursday and Friday will be the worst. Heavy rain, high surf and gusty winds will be likely, so get your movie tickets soon!

Saturday and Sunday will be sunny and warm, but dangerous rip currents will continue to be a likelihood as the remnants of the storm move farther northeast into the Atlantic. Keep this in mind if you are heading there and be sure to check with the lifeguards before entering the water if you aren't a strong swimmer or familiar with rip currents.

Check back here for the latest updates.

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