Friday, July 12, 2013

A Hemi / Demi / Semi D.C. Area Midnight Hour Deluge -OR- Quasi-stationary Monsoon

Sterling (LWX) NWS radar in enhanced composite mode at 12:28AM EDT July 12, 2013.

Composite mode shows both what is falling from the clouds and internal cloud activity, so it tends to look more dramatic in convective situations such as this.


Torrential rains / t-storms have set up literally a few miles from where I am around Dupont Circle and extending to the north and west in an arc around the District of Columbia. Dulles Airport climate station (KIAD) has had at least 3 inches of rain in the past two hours.

LWX NWS radar in base mode reflectivity also at 12:28AM EDT July 12, 2013.


The sky is really dramatic looking as seen from my 5th floor apartment looking across the miles from the southwest to the northwest with a low-hanging shelf (arcus) cloud that is being illuminated by frequent flashes of electric blue lightning. The skyline of Rosslyn is still visible. To the northwest, things sort of disappear behind the rise of Meridian Hill Park and the nearby buildings of the Brittany and the Camden-Roosevelt, both of which front onto 16th Street.  Alas, I cannot take a picture of any of this with my low-quality cellphone camera.

Sterling (LWX) county warning area (CWA) weather advisories in effect as of 12:29AM EDT July 12, 2013. The crimson/dark red colors are flash flood warnings.


The low dull grumble of thunder is also audible. The entire District of Columbia is under a flash flood warning even though the rain at this precise moment (12:29AM) has not yet reached much beyond far upper Northwest D.C., and certainly not at National Airport climate station (KDCA).

A quasi-stationary frontal boundary with its convergence zone has set up right over the immediate Baltimore / Washington area aligned NE to SW. There is a deep southeasterly flow over to the east of the boundary. (This SE flow has been a frequent feature this non-hellishly hot and relatively wet summer.)

Above: A close-up of the NWS / WPC surface analysis valid at 0000Z July 12, 2013 (8PM EDT July 11, 2013) issued at 0124Z July 12, 2013 (9:24PM EDT July 11, 2013).

It is 1230AM and it is NOW beginning to rain outside. However, this could be a situation where KIAD gets far more rainfall than KDCA with KBWI splitting the difference.

(Updated image): LWX enhanced composite mode radar at 1:00AM EDT July 12, 2013 close-in on central Maryland and northern Virginia.


Changing subjects, I have a new worry at work, but I'll refrain from discussing that right now. I did not go to the gym tonight (I'm still hurting a bit from last night) but instead I walked home -- it was a semi-harrowing walk across downtown owing to snarled traffic heading up 12th Street NW. I stopped for two drinks (two for one special) at No. 9 before walking home.

That's all for now. I'll update this entry as necessary.


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