Friday, October 5, 2007

21 Days and Counting
Rainless streak expected to extend into next week


Partly sunny, warm, humid. Today is the 21st consecutive rainless day since a mere 0.15" fell in the official precipitation bucket at National Airport on Sept. 14. It's not as bad as what The Weather Channel has taken to calling the "desert southeast", but the latest drought monitor map shows the Severe Drought category (dark brown) extending northward from Virginia across DC and most of Maryland, while the Extreme Drought area is pushing into southern Virginia toward the Richmond area. Fairfax City (not County) is now the latest local jurisdiction to impose water restrictions.

Temperature-wise, the retreat westward of the center of high pressure to the north of the area has shifted the wind more to the east. This has kept enough clouds around to prevent temperatures from reaching the more optimistic forecast levels. Although Dulles, Leesburg, and BWI had all reached or exceeded 80° by mid afternoon, many other locations were still in the upper 70s. National was at 80° by 4pm with scattered clouds at around 3200 ft. Dewpoints are actually a couple of degrees lower than yesterday, but still in the noticeably humid range.

U.S. Drought Monitor map released yesterday by NOAA/NESDIS/NCDC

Tonight and Tomorrow

Warm, humid. Tonight will be continued warm and humid with some low clouds and patchy fog by morning; lows will be from the upper 60s downtown to the low 60s in the 'burbs. Morning clouds tomorrow will give way to mostly sunny skies in the afternoon with highs 82-86°

For the outlook through the rest of the Columbus Day weekend, scroll on down to Camden's post below.

Energy Watch

The latest post at The Weather Channel's Forecast Earth blog, "$1.8 BILLION FOR MARYLAND POWER LINES?", is an interesting analysis of the tradeoffs between investment in long-distance power transmission and smart grid technologies. The post is by Jigar Shah, Chief Strategy Officer of SunEdison, which is based in Beltsville. The company is "North America's largest solar energy service provider." The transmission line in question is intended to bring more coal-generated power from the Midwest into the state. According to their latest report, Pepco currently derives 54% of power from coal and only 3.8% from renewable sources, of which 0% is solar.


This week's Forecast Earth broadcast (5pm Saturday and Sunday) is focused on nuclear energy.

CNN's Rob Marciano is the latest broadcast meteorologist to jump into the political crossfire over global warming.

Thursday, October 4, 2007

DC: Desiccated Community


Mostly sunny, warm, humid. Increased humidity and nearly calm winds produced some dense fog overnight in the Washington metro area. Visibilities plunged as low as half a mile at National, a quarter of a mile at Dulles, and an eighth of a mile in heavy drizzle at BWI.

The return of the sun, however, has pushed temperatures mainly to the mid and upper 80s by mid afternoon, although the river-cooled south wind is keeping National several degrees lower. Dulles at least tied the record for the date with 87° at 4pm and again the following hour. Traditional hotspot Culpeper reached 91° by 2pm. The dewpoint reached 70° by noon at National and has remained within 1° of there all afternoon.

Once again, no significant rain is in sight, and a regional government committee has issued a drought watch. On Tuesday, Loudoun County imposed mandatory water restrictions. chart of visibility (blue) and relative humidity (green) noon yesterday through early afternoon today from NWS data, photo © Kevin Ambrose

Tonight and Tomorrow

Warm, humid. Warm and humid conditions will continue overnight; AC usage at the typical start of the heating season seems like sacrilege, but the hum of the compressor will likely be heard in many neighborhoods. Lows will be in the upper 60s to near 70° in the city and in the mid 60s in the 'burbs. Some locally dense fog is again likely after midnight. Any morning fog or clouds will give way to a mostly sunny afternoon tomorrow with highs 83-87°. (Tomorrow's record high of 90° at Dulles is also the all-time October high.)

For the outlook through the Columbus Day weekend and beyond with Larson's Long-Range, scroll on down to Josh's post below.

Tropical Topics

The tropical Atlantic is still relatively quiet; the reconnaissance flight scheduled for the Gulf of Mexico this afternoon was canceled.

Mediarology: Hype Alert

The Weather Channel's Stu Ostro tries to apply some scientific sense to the media's Niño/Niña obsession in a blog post today, "Oh No! La Nina is Coming!"

Wednesday, October 3, 2007

Same ol' Sol


Mostly sunny, warm, humid. Probably one reason October is Matt's favorite month is that it has, on average, by far the highest number of clear days (10.7, over 10% higher than its nearest rival, September, although the month just ended had 15 clear days).

That's not the case today as persistent clouds overnight and even some morning drizzle have kept the low so far today to the balmy midnight reading of 68°. On the other hand, a more southerly than easterly wind has allowed an abundance of sunshine to push temperatures into the low and even mid 80s in some places this afternoon. Humidity has also increased; dewpoints in the mid and upper 60s are nearly 10° higher than yesterday. chart from NWS data, photo © Kevin Ambrose

Tonight and Tomorrow

Warm, humid. Some low clouds and patchy fog are likely to form again tonight; lows will be in the mid 60s downtown to the upper 50s in the 'burbs. Any morning clouds should burn off in time to produce a mainly sunny day tomorrow with highs 83-87°.

For the outlook through the rest of the week and into the Columbus Day weekend, scroll on down to Jason's post below.

Tropical Topics

There are no active storms in the tropical Atlantic or eastern Pacific, but the National Hurricane Center is still keeping an eye on a low pressure area in the eastern Gulf. The reconnaissance flight scheduled for today was called off, but this system still has some potential for development. Meanwhile, another area a little east of the Bahamas is encountering more favorable upper level winds and could become a tropical depression in the next couple of days.

The Gray team at Colorado State have revised their hurricane season forecast (again).

Book Sale

Get 'em while they're hot: As a public service, we waive the usual Amazon referral fee to note that the Oxford University Press has several weather-related books in its Fall Sale: None of these titles come with any recommendation from the management, staff, or advertisers of, but this is a very well respected publisher, especially in the area of reference books.

Monday, October 1, 2007

DC: Drought Continues


Mostly sunny, warm. With Thursday's rain focused mainly to the north and west of the Beltway (only a trace at National), the month just ended finished out in the top 5 of driest Septembers in Washington. As Dan details below, this first week of October is getting off to a dry start as well.

As high pressure centered over extreme eastern Canada slides slowly off the coast, a more easterly wind has brought in a little more humidity, a few more clouds, and very slightly cooler temperatures this afternoon in the metro area. By mid afternoon, temperatures at local reporting stations were generally in the mid 70s and dewpoints were in the comfortable mid 50s.

24-hour precipitation ending Friday morning from NWS Precipitation Analysis shows amounts up to 0.5" (dark blue) across much of Montgomery and Fairfax Counties with a few higher amounts, but much less across DC and to the south and east.

Tonight and Tomorrow

Warm, becoming a little more humid. Under scattered to broken clouds, lows tonight will range from the upper 50s in the city to the low and mid 50s in the 'burbs. There is a chance of some fog in low lying areas. Tomorrow will be mostly sunny with highs 76-80° and a little more humidity.

For the outlook through the rest of the week and into the Columbus Day weekend, scroll on down to Dan's post below.

Tropical Topics

Melissa developed near the Cape Verde Islands on Friday, briefly became a tropical storm over the weekend and quickly dissipated. Neither the remnants of Karen nor Melissa are expected to redevelop.

The only other significant area of interest in the Atlantic is over the Bahamas, Florida, and the adjacent Atlantic. Some slow subtropical development is considered possible for this system in the next couple of days.

Making Lemonade Out of Lemons

For an idea about what to do with all this excess sunshine (although the temperatures are a bit warm), check out the article about the rechargeable jacket in the Sept. 24 New Yorker (article not available online). The Solar JKT from fashion designer Zegna of Italy comes with solar panels on the collar for recharging an iPod (spellcheck suggests "Izod", probably not compatible with Zegna) or cell phone.

Seasonal Outlook

Latest seasonal forecast: Click here.

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