From the ABC 7 Weather team

Archive for category Just For Fun August 2014

Coolest August morning in 10 years? It's possible Friday

August 14, 2014 - 01:02 PM
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So far, the month of August has been slightly cooler than normal. There have only been two days this month with above-average temperatures. Now, let me set the record straight: It hasn't been abnormally cold so far this month, but it will definitely be much cooler than normal over the next two days.

(Forecast morning lows Friday)

Low temperatures Friday morning and Saturday morning may drop into the 50s at Reagan National Airport. This hasn't happened in 10 years, since August 7th, 2004, when the mercury dropped to 58 degrees. Since 2009, temperatures haven't dropped into the 50s at Reagan National until September 1st, the 11th twice, the 14th and the 15th, so we're nearly a month ahead of where we've been over the past few years.

The average low doesn't eclipse the 50s until September 24th. Looking back a little further into the climate data, temperatures in the 50s in the month of August have been largely absent in D.C. after 2004.

There were numerous times prior to that date though, as Reagan National reached the 50s in August in 2000, 1998, and 1997, four times in 1994, once in 1992 and two times in 1989. That gives 12 occasions in the past 25 years, though none in the past 10. I guess we'll see if we can break the warm streak starting tonight.

(Secondary cold front will move through this evening)

The forecast low tonight for D.C. is 60 degrees. As a secondary frontal boundary pushes through the region this afternoon and evening, drier air will settle overhead along with clearing skies overnight. By the early morning, clear skies and light winds should lead to plenty of radiational cooling, which may help D.C. reach its potential. The wild card: The Potomac's water temperature still stands at 77.5 degrees. A slight shift in the wind could keep the temperature from dropping below 60.

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Areas of heavy rain in the D.C. area Tuesday

August 11, 2014 - 02:06 PM
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An area of low pressure continues to move into the Great Lakes region today and an associated frontal boundary will bring the possibility of heavy rain through Tuesday. Showers will begin Monday evening, rather light in nature, and will continue to overspread the D.C. area overnight.

Surface map for Monday Evening

The Tuesday morning commute may be a wet one, but the heaviest rainfall is expected to fall Tuesday afternoon and evening. A few embedded thunderstorms will be possible, and some locations may see the potential of 1 to 2 inches of rain with isolated higher amounts.

RPM Precipitation Forecast

Our in-house RPM model shows the potential for much of the D.C. area to be closer to the 0.5" to 1" range, with isolated spots mainly north and west of D.C. with the higher amounts. This is in line with other modeling as well as the excessive rainfall discussion, which is pegging the state of Pennsylvania with the potential for the heaviest rainfall.

While ponding on the roadways will be possible, flooding doesn't appear to be a big threat at the moment. However, if some of the heavier showers and storms begin training over the same locations, some localized flash flooding may be possible, especially by the afternoon and evening hours on Tuesday.

Rain should wrap up for the most part overnight Tuesday into Wednesday morning. Drier air will filter back into the area Wednesday afternoon and at this point, conditions look about perfect Thursday through Saturday with plenty of sunshine and comfortable temperatures in the lower 80s.

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Supermoon and Perseid Meteor Shower

August 10, 2014 - 05:00 AM
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A lot going on in the night sky over the next several days.  The August full moon, which occurs tonight, may look a little bigger and brighter than normal.  In fact, it will be 14% bigger and 30% brighter.  The reason is because the moon is at lunar perigee.  This means the moon is about 30,000 miles closer to the Earth than normal.

NASA

You'll have to wait for breaks in the clouds to see the bright moon Sunday night.  If you don't get a chance to see the moon tonight, you'll get another chance at catching a 'supermoon' when it happens again on September 9, 2014.   The August supermoon will be the closest of all supermoons this year.  The moon will not be this close again until the full moon on September 28th, 2015.

NASA

Another fantastic night sky event is the annual Perseid meteor shower.  One of the most vibrant meteor showers of the year with nearly 60 to 100 meteors in an hour from a dark place at peak. The only caveat is the perseids will be competing with the very bright supermoon.  The perseid meteor shower peaks on the mornings of August 11th, 12th, and 13th. 

NASA

As for local weather, conditions won't be ideal for supermoon and meteor shower viewing.  It looks like skies will be rather cloudy for the next few nights with clear skies returning by Wednesday night.  You should still be able to see a few shooting stars by midweek, with the still bright waning gibbous moon.

The Stormwatch weather team would love to see your supermoon pictures.  Upload them to our Stormwatch Facebook page and maybe you'll see them on air! 

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