Friday, May 3, 2013

It's a Very Fine Dandelion Wine*: On Omega Blocks, Vorticity Lobes, Backdoor Fronts, and Morning Stratus in a Cerulean / Azure Sky

A fine wine dandelion* (!) growing in the small grassy "yard" along 15th Street between Massachusetts and Rhode Island Avenues NW, Washington, D.C., 7:59PM May 1, 2013.

*With apologies to the late, great Ray Bradbury for both the blog entry title and caption.


I was going to post a new entry but it is already the 130AM hour, and I am so tired after a day at work and then a good gym workout (comparable to the Monday and Tuesday ones). Tonight, I updated this blog entry -- prompted by reasons I plan to explain in a subsequent entry. I intend to post a Friday night musical interlude.

This should be a normal / regular D.C. weekend for me, but next weekend I am supposed to go with Andrea & Co. on a weekend camping trip to western Maryland (near Hancock). I have to get a sleeping bag this weekend since (surprise) I don't have one.

The view from Pizza Autentica looking outside onto 15th Street NW, Washington, D.C., 7:52PM May 1, 2013.

I was heading to No. 9 on Wednesday evening (I skipped the gym that night) to meet Kristof but had to get something to eat.


The weather remains a bit anomalous with a maritime polar high off New England nosing down the U.S. Eastern Seaboard while an unseasonably cold cutoff low with surface reflection slowly spins over the mid-Mississippi River valley. It has brought late season snowfall to the Upper Midwest into the central and northern Great Plains (having cleared the Rockies) while ahead of it rainfall is streaming south-to-north into Missouri, Illinois, and Iowa.

The NWS 24-hour surface map forecast for the contiguous U.S. valid at 00Z 05 May 2013 (8PM EDT May 4, 2013).


Highs reached 68F at KDCA, 67F at KBWI, and 69F at KIAD -- all 3 to 4F below normal highs -- with dew points mostly in the 42F to 46F range. There were low stratus clouds this morning but it soon cleared up with cloudless spectacularly cerulean (or is it azure?) blue skies. Unfortunately, we really need some additional rainfall.

The 00Z 03 May 2013 GFS showing 500mb heights and vorticity valid at hour 18 / 18Z (2PM EDT) May 3, 2013.

In the animated loop, a "bowling ball" of vorticity ever-so-slowly rolls across the southern U.S. toward Georgia by Tuesday.

The 00Z 03 May 2013 GFS showing 500mb heights and vorticity valid at hour 75 / 3Z May 6, 2013 (11PM May 5, 2013).

The two closed height contours / vorticity lobes on either side of the United States remind me of this cheap silk screen painting my dad had of a nude woman when I was a little boy in New Jersey that hung over his bed (which I shared with him for years). Or of a weird monster.


The upper level low may slowly spiral toward the Ohio River valley and toward the Eastern Seaboard by Tuesday as the high finally recedes. In the meantime, though, there is already a coastal / backdoor front that at the 2AM hour is over New Jersey and may make it to the D.C. doorstep with stratus clouds by dawn.

A portion of the high-resolution NWS surface map for the United States showing the Northeastern U.S. valid at 3Z May 3, 2013 (11PM EDT May 2, 2013).


And another vorticity lobe may move down the coast (southward) on the backside of an upper level low located in the western Atlantic. There is a fairly dramatic Omega-block pattern in place now across North America.

The cirrus shield from the central US low is already overspreading the area, but the block pattern is still in place.

L'Enfant Plaza North as seen from the Aerospace Building upper floors, Washington, D.C., 7:22PM May 1, 2013.

Yes, it looks Hopper-esque.


Oh, yes, speaking of these airport climate station, the FAA has decided for the time being to keep funding the contractors who take the observations rather than handing it off to the air traffic controllers. (No, the NWS does not typically keep these airport climate station records.)

A jet take off from Reagan National Airport with the U.S. Capitol Building prominently visible along with other buildings and structures while in the nearer-in foreground are seen the Potomac River and East Potomac Park. I got this picture from the above CWG link.


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