From the ABC 7 Weather team

Archive for category The Outside Story September 2014

Only A Few Days of Summer Left Before Autumn Begins

September 19, 2014 - 02:19 PM
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Enjoy this last weekend of summer - because it is going to feel more like summer here in the Washington D.C. area! Temperatures throughout this last week of summer have been running below normal giving us a little taste of Fall.  However, by the time we head into this weekend, temperatures will top out in the 80s for much of the region thanks to high pressure clearing out cloud cover and helping us boost into the 80s with a light southeasterly flow.

A cold front will cross the area Sunday which will give way to some clouds and about a 30% chance of showers in the afternoon and evening hours moving from west to east. This cold front will also sweep away any of the summer-like weather we have left and leave us with another spell of Autumn weather around the region.

This is happening right in time because the autumnal equinox arrives at 10:29 p.m. on Monday! People celebrate this moment across the world and really the precise moment is when the sun passes directly over the equator! This happens twice a year as you may recall (the "spring equinox" and the "autumnal equinox"). 

 

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In latin, the word "equinox" means "equal night" --"equi" meaning "equal" and "nox" meaning "night". This signifies the equal parts of daylight and darkness.

However, this is not always so "matter-of-fact." The sunrise on Monday is 6:55 a.m. and the sunset is 7:07 p.m. This isn't exactly equal. In fact, we have to wait until Tuesday, the first full day of Autumn to get the full equal light-equal night. The sunrise on Tuesday is 6:56 a.m. and the sunset is 7:06 p.m.

My colleague Eileen Whelan summed it up correctly when she wrote:

"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 10:29 p.m. EDT on Monday, September 22. At the same time the equinox occurs in D.C., it occurs across the globe."

Either way, you won't notice a different from Monday to Tuesday, from Summer to Autumn. However, you will notice that the hours of daylight start getting shorter until the Winter Solstice which begins on December 21, 6:03 P.M. EST (which is also the darkest day of the year meaning the day with the least amount of daylight.

However, as we make the transition into Fall, it may seem a little cooler according the outlook by the Climate Prediction Center:

 

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But, also according to the Climate Prediction Center for the 8-14 day outlook, temperatures may be a little on the warmer side!

 

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So don't pack away those flip-flops yet for those boots. Fall is here to stay but bouts of summer may stick around until early October!

 

 

 

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Dry start to September in the D.C. area, dry outlook ahead

September 16, 2014 - 12:06 PM
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Over the past few weeks, a few locations saw some moderate to heavy rainfall from storms but they were highly localized. Here are some of the locations that have seen decent rainfall this month on our WeatherBug Network.

Monthly Rain and temps as of Noon Tuesday on our WeatherBug Network

Other parts of the area haven't been quite as lucky as of late, with official reports at the local observation stations capturing relatively little rain for the month of September. Officially, precipitation totals so far this month are running anywhere from 1" to 1.5" below normal. Unfortunately, the current outlook isn't going to bring appreciable rainfall anytime soon.

Rainfall by the numbers this month and for the year

Above is a look at how the region is faring as far as precipitation this September. Dulles Airport is struggling the most, with only 0.21" of rain in the first 16 days. The observation station is running over an inch and a half below average for the month.

BWI Marshall has been the closest to average precipitation but is still running around an inch below for the month.

Maryland Drought Monitor

As far as the drought monitor is concerned, the region isn't even abnormally dry. This may change over the next week or two, but looking at the statistics for Virginia and Maryland, there aren't any regions with drought in Maryland and only a few abnormally dry spots south of D.C. in Virginia.

Virginia Drought Monitor

Much of this is due to the fact that the region has such a big surplus for the year and stayed around normal over the summer months. Precipitation is still running nearly 6 inches above average for the year at Reagan National and over 9 inches above average at BWI Marshall.

QPF today through next Tuesday morning from the WPC

The forecast looking ahead over the next few weeks doesn't look to good for rainfall chances in the D.C. area. The WPC forecast above only brings about a chance for light rain over the next week, and other modeling continues to depict dry conditions even through next week. A few showers may be possible with a cold front next Monday into Tuesday, but beyond that the region may not see decent rainfall until after the following weekend of the 27th and 28th. We'll of course keep you up to date with our latest 7-Day Forecast.

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Sunday Night "Mysterious Flash of Light" in the Sky

September 15, 2014 - 07:53 AM
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Many reports have been coming in of people in the D.C. region seeing a bright flash in the sky last night. It happened just before 11 p.m. Eastern Daylight Time. Most reports on the American Meteor Society website are described as a bright white or yellow flash that lasted around one second. Here is a map of all of the reports:

(Meteor Sightings via American Meteor Society)

So, what was it? Most likely, it was a meteor. Meteors are pieces of rock, ice and dust, usually from a comet, that explode and burn up as they enter the Earth's atmosphere. There are two meteor showers taking place in the month of September. First, the Southern Taurids, which are active for two months from Sept. 7-Nov. 19th. According to the American Meteor Society, they tend to produce few "shooting stars" but can be rich in fireballs and often responsible for an uptick in fireball reports to the society's website. In addition to the Southern Taurids, the less known Piscids will be near their peak in September and continue through October.  Check out this article from In-The-Sky.org. Let us know if you saw anything: Just go to our Stormwatch7 Facebook page and leave a note. 

Update:

This video was taken from Jesse Ferrell who works for Accuweather in State College, PA. You can see how the fireball completely lit up the night sky.

Here's another look at the meteor from Jeremy Settle, Assistant News Director at News 12 in New Jersey.

 

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Hottest stretch so far this year looks to continue into September

September 1, 2014 - 08:16 PM
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After a hot end to August, the heat doesn’t want to go anywhere for the beginning of the month. Check out the 7-Day forecast here. Tuesday through Saturday all appear like they will at least be close to the 90 degree mark, with the hottest day for the remainder of the week Tuesday. Oddly enough, Reagan National Airport hasn't recorded four days in a row with highs at or above 90 degrees this year. The 15th through 21st of July 2013 was the last time we've experienced a prolonged period of high heat, with 7 days in a row at or above 93 degrees.

Last September also started off on a hot note, but beyond the first few weeks there was a nice cool down with a long stretch of days in the 70s. The average high is 84 degrees to start the month, but falls to 74 degrees by the end of the month.

90 degree days as of September 1

Temperatures should get back near normal come Sunday as cooler air moves in after a cold front. For the year, D.C. is still below the normal number of 90 degree days, with 19 as of Monday, compared to the 28 we were at by September 1st in 2013, and compared to the 36 average D.C. typically records in a year. With the recent hot summers, however, this is nothing compared to the record 67 90-degree days in 2010 or even the 56 in 2012, so at least it has been nice!

Monday's rainbow over D.C. captured by Richard Barnhill

Check out this beautiful picture from Richard Barnhill. You can find him on social media here and here, and check out his other pictures on flickr here.

What about storm chances the rest of the week? After a stormy past two days in parts of the area, a cold front will move into the region late Tuesday bringing an additional chance for afternoon storms. A break in the action will be likely Wednesday and Thursday before chances return Friday in an isolated nature and more widespread action with a potent cold front on Saturday.

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