Friday, April 14, 2006

Drought Eggstended Another Day

Today's weather is a good lesson in insolation. No, not the stuff you put in your attic. Thanks to the inclination of the Earth's axis, the incoming solar radiation today, 24 days after the Equinox, is roughly the same as it was on August 28. (So don't forget the sunscreen, boys and girls!) With the persistent cloud cover over the region, however, temperatures have been slow to climb, even with a brisk southwesterly wind gusting over 20 mph. On the other hand, by mid afternoon, breaks in the clouds were allowing temperatures to reach the mid 70s.

Sprinkles associated with the clouds were mighty few and far between. Among the major local airports, BWI was the winner of the rainfall derby by far, with 0.01" eclipsing the trace at Dulles and zero at National. At mid afternoon, radar showed a band of showers from southeastern Pennsylvania to just north of Baltimore and another area southwestward from Charlottesville. Although some more showers could pop up through this evening, mainly dry conditions will prevail in the metro area.

To the west, temperatures soared under high pressure through the central part of the country. The Weather Channel reported that over 40 temperature records were set in the Midwest yesterday.

Surface weather map and satellite picture at 2pm today from HPC/NCEP/NWS

Tonight and Tomorrow

Temperatures tonight will have a hard time getting below 60 in the city under broken clouds while the 'burbs should see temps in the mid to upper 50s. Tomorrow, fewer clouds in the afternoon should have June-like conditions busting out all over with highs around 80, although there is a chance of showers, at least in the morning and possibly again late in the afternoon.

Smithsonian Plays it Cool

Two new exhibits on climate change open at the Smithsonian Natural History Museum today. They were previewed by Joel Achenbach ("Hot Air and Glacial Change: A Case Study") with his inimitable style in the WaPo on Wednesday. (CAUTION: Achenbach's columns contain over 100% of the Recommended Daily Allowance of irony; they have been known to generate severe knee-jerk reactions.) Achenbach concludes, "It's all rather low-key." It's so low-key that the exhibits didn't even appear on the museum web site until the last day or two. The exhibits are: "Arctic: A Friend Acting Strangely" and "Change is in the Air". They are both scheduled to run through November.

Picture of the atmosphere from space by NASA, via Smithsonian National Museum of Natural History

It Ain't Over Til Momma Nature Says it's Over

Just when you thought the hurricane season of 2005 had gone into the history books with a record 27 storms, the National Hurricane Center has announced that reanalysis shows a low near the Azores on October 4-5 was an unnamed subtropical storm, making a total of 28 storms for the season. There are 48 days until the official start of this year's hurricane season.

Thursday, April 13, 2006

DC: Deficit Capital

A very weak frontal boundary moving through early this afternoon touched off some thunderstorms in the southern portion of the Washington DC region. Moving southeastward from Fauquier and Prince William Counties in Virginia, the storms crossed the Potomac into Charles County, where they prompted a severe thunderstorm warning, which was cancelled shortly after 3pm. Site visitor PC reported nickel-sized hail in eastern Prince William.

At post time, radar showed some scattered light activity south of the District, but the earlier area had intensified over the lower Chesapeake Bay, just south of the mouth of the Potomac. For the rest of the afternoon and evening, a few more isolated storms could pop up, but conditions will be mainly dry. See Josh's post below for the chances of receiving some much-needed rain over the weekend.

Surface weather map and satellite picture at 2pm today from HPC/NCEP/NWS

Tonight and Tomorrow

Lows tonight will remain quite mild for the season, mid to upper 50s, under partly cloudy skies. Today's models are showing an unusually wide range of temperatures for tomorrow, but a consensus target somewhere in the mid 70s looks reasonable, with sun through broken to overcast skies. The chance of showers, especially in the afternoon, is 40%.

Deficits Matter

The Nation's Capital has been the home of "Red Ink Run Amok" for quite some time, but it is also recently experiencing a deepening precipitation deficit. The chart shows the accumulated precipitation this year as a percentage surplus or deficit relative to the long-term average. Following a January which was almost exactly "normal", early February was quite wet, but the surplus was more than wiped out by the record-breaking dry March, and the rain so far in April has barely maintained the status-quo. Although a holiday weekend is coming up, that sound you hear is from the lawns and shrubs throughout the region crying out for more moisture. chart from NWS data, photo © Kevin Ambrose

Tuesday, April 11, 2006

A Beautiful Day in the Neighborhood

"It's a beautiful day in this neighborhood", with even the Anomalous Airport reaching 70° by early afternoon. Many other locations in the Washington DC metro area were in the mid or upper 70s at mid afternoon. Here at Afternoon Blog Central, it's up to an unofficial 78&deg.

It's also still very dry, although not as much as Ft. Belvoir's continuing bogus 11% relative humidity. My first lawn mowing of the season today was probably as late as any in the last 16 seasons at this address. That's probably due to the record-breaking dryness of March, since temperatures have not been particularly cold. Thanks to the rain last week and over the weekend, we're still about a third of an inch above normal for April, but that excess is likely to be dissipated within the next couple of days.

Tonight and Tomorrow

Tonight will be mostly clear with lows around 50. Tomorrow, clouds will increase, especially in the afternoon, with highs in the low 70s.

Space Weather

In the nearby Solar System neighborhood, the European Space Agency Venus Express mission was successfully inserted early this morning into orbit around Earth's evil twin. Venus' atmosphere is an example of the greenhouse effect on steroids. The nearly 100% CO2 atmosphere has about 90 times the density of our own atmosphere. This results in a surface temperature of about 470° C, even higher than the surface of Mercury and hot enough to melt lead. Unlike an earlier mission whose main purpose was to map the surface of the planet, Venus Express is designed to study the atmosphere. For some interesting background information, see the latest post at

Graphic from European Space Agency

Monday, April 10, 2006

60s and 70s Greatest Hits

A big fat high pressure area parked over the Mid Atlantic region is allowing a strong dose of "Mellow Yellow" through the bright blue sky. Along with a "Wind-a velocity nil", it's a "So Fine" day here in the Washington DC metro area. If you don't have your mower ready for the season yet, it's "too late baby, now." With the weekend's rains and the "Good Day Sunshine", the roar of the 2-cycle engine will soon be abroad in the land.

Surface weather map at 1pm today from IntelliWeather

By early afternoon, temperatures had reached or exceeded 60 in all locations, but the dewpoints in the upper 20s or low 30s (except Ft. Belvoir!) made it almost impossible to break a sweat. Winds were variable mostly under 5 mph.

Tonight and Tomorrow

Lows tonight will be from the mid 40s city to upper 30s in the colder 'burbs under mostly clear skies. Tomorrow will be much like today, but with temperatures warming to around 70.


The PBS NOVA science series is showing its annual rerun of "Hunt for the Supertwister" tomorrow night (8pm locally on WETA, channel 26). The program, which I have now seen twice since it was first broadcast 2 years ago, puts a lot of emphasis on Discovery-Channel-style storm chasing, but it has much better production values than the Weather Channel's "It Could Happen Tomorrow" series. It also manages to get in some real science, including by meteorology professor/storm chasing pioneer Howie Bluestein of the University of Oklahoma.

Image from

Party On

A tip of the hat to site visitor PJ, who pointed out that the local National Weather Service Forecast Office in Sterling is inviting the community to an open house the last weekend of this month, from 9 to 5 on Saturday the 29th and noon to 5 on Sunday the 30th. There will be presentations on "Aviation and Marine Operations, Fire Weather, Tropical Weather, Severe Weather, CO-OP Program, and Hydrology." You can also attend a Skywarn class to become a certified weather spotter.

Seasonal Outlook

Latest seasonal forecast: Click here.

Latest 3-month temperature outlook from Climate Prediction Center/NWS/NOAA.