Friday, February 23, 2007

Windy Cold At Bat; Wintry Mix On Deck

*Winter Storm Watch in Effect Late Saturday Night Through Sunday Night*


Windy, cold. We're in the late innings, but winter isn't ready to put away the bat just yet. Winds peaking as high as 55 mph overnight have made it feel a lot colder than the near 40° temperatures this afternoon in the Washington metro area, especially after the relatively balmy experience of 3 consecutive days above average (and above freezing). Highs were 41° at National, 39° at Dulles, and 38° at BWI.

A low pressure area just now becoming organized in the central Rockies will deepen and move northeastward toward the Great Lakes, bringing with it the threat of some wintry precipitation in the Mid Atlantic region Sunday.

Tonight and Tomorrow

Clear, less windy, cold. Under clear skies and diminishing winds, lows tonight should be from the low 20s downtown to the mid and upper teens in 'burbland. Tomorrow will be mostly sunny and continued cold, less windy than today with highs 42-45°

For the outlook through the rest of the weekend, including Sunday's potential wintry mix, scroll down to Camden's post below.

Tropical Topics

Winter may be still batting, but tropical season is just over 90 days away. Here at PM Update, we're getting in the mood by starting to read Ivor van Heerden's "The Storm", a scientist's on-the-scene report of the Katrina experience. From the tone of the introduction, it appears that he will be pulling no punches in his analysis of what went on.

Meanwhile, yesterday the National Hurricane Center published their annual post mortem analysis of forecast accuracy for last year's storm season. The good news: Atlantic track forecast accuracy set new records in the range from 12-72 hr., beat each individual dynamical model, and only slightly trailed the consensus models. The bad news: Intensity forecasting continues to be a formidable problem. Intensity accuracy was close to the average of the last 5 years, but skill levels (improvement over average conditions, or climatology and persistence) were "down sharply."

Chart of hurricane track forecast accuracy in nautical miles at 24, 48, 72, 96, and 120 hr., years 1990-2006, from NHC

Thursday, February 22, 2007

Spring Pops Up; Winter Attempting to Rally

*Wind Advisory in Effect Through 10am Friday*


Windy, turning colder. Some light showers (0.01") and even the sound of thunder in some places ushered in winds gusting over 40 mph at times as a cold front south of an energetic clipper system moved briskly eastward through the Washington metro area today. Temperatures, however, again exceeded expectations, popping up to the nearly spring-like upper 50s before they began to drop around mid afternoon. Highs were 59° at National, 56° at Dulles, 55° at BWI. To the south, Charlottesville and Richmond were both in the low 60s.

Winter will be attempting to stage a comeback in the next couple of days as below-average temperatures return along with a marginal possibility of some more winter-like precipitation on Sunday.

Surface weather map at 1pm today from HPC/NCEP/NWS

Tonight and Tomorrow

Clearing, windy, colder. Lows tonight under clearing skies will be in the upper 20s to near 30°. Tomorrow will be mostly sunny and breezy with highs only in the low 40s.

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

Winter Thunder

The 30-year climatological average is 1 February thunderstorm every 5 years in Washington, but thunder has now been observed in 2 consecutive Februarys and in 3 out of the last 5. The previous occurrence to last year was in 2003.

Mediaorology: Channel 4 Sweeps V-Day Storm Coverage

Yesterday's WaTi business section had an article, "TV news makes hay out of snow" about the local news ratings during the Valentine's Day storm and the implications of the weather coverage for the all-important February "sweeps" period. The corrected rankings in today's dcrtv blog show WRC-4 in first place for all 3 time slots (6am, 5pm, 11pm), followed by WJLA-7 at 6am and 5pm; WTTG-5 was second at 11pm. WUSA-9 was last at 6am and 11pm and 3rd at 5pm. WRC's score was at least 50% above the last-place station in each set of ratings; it was over 4 times the last-place WUSA-9 at 11pm. chart from Washington Times data via, photo © Kevin Ambrose

Wednesday, February 21, 2007

Winter Strikes Out


Sunny, seasonably mild. There are still a few more innings to be played, but winter has struck out in the Washington metro area, at least for now. Despite a northerly breeze, mild Pacific air and strong sunshine pushed temperatures beyond the optimistic end of the forecast range by mid afternoon, reaching the mid 50s. Highs were 56° at National, 52° at Dulles and BWI. After 7 consecutive days with 1" or more of snow/ice on the ground, melting has reduced the depth to 0. The melting was helped by the 0.25" of showers which fell last night. Freezing temperatures throughout the country have retreated to near the Canadian border.

Temperature chart at 3pm today from Unisys

Tonight and Tomorrow

Partly cloudy, mild. Lows tonight will be in the mid to upper 30s under partly cloudy skies, with some low 30s in the cooler 'burblands. Tomorrow will be variably cloudy with highs near 50°, but becoming breezy and colder late in the day. There is a 30% chance of showers in the late afternoon or evening.

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

Climate Corner

Today's WaPo reports that the Maryland House of Delegates has approved with a wide bipartisan 122-16 margin a bill to regulate auto CO2 emissions. Following inaction at the federal level, 10 other states have already enacted regulations based on those established in California. Senate approval is expected, and Gov. O'Malley has promised to sign the bill, which requires new vehicles sold or registered in the state to have an average fuel economy of 43 miles per gallon by model year 2011.

Tuesday, February 20, 2007

Spring Training


Mostly cloudy, seasonably cool. It's not quite spring-like, but except for a slight dip around noon, temperatures have been steadily rising since 8pm last night to more seasonable levels in the Washington metro area. Persistent clouds and a slowly melting ice pack kept readings in the immediate area to the mid and upper 40s, but sunnier locations as close as Fredericksburg exceeded 60°, and the 60s were common southward and eastward through the rest of Virginia. Today's high of 47°, with the midnight low of 37°, makes this the first day this month with above-average temperatures.

The nearest precipitation is an area of showers in the Ohio Valley. Some of these showers ahead of a weak cold front should arrive overnight, to be followed by drier and seasonably mild conditions tomorrow.

Tonight and Tomorrow

Scattered showers, followed by clearing and seasonable. There is a 60% chance of rain showers overnight with lows in the upper 30s to around 40°. Clouds will decrease tomorow with highs 48-52°.

For the outlook through the rest of the week, scroll down to Jason's post below.

Climate Corner

The board of the AAAS, the world's largest general science organization, released a statement on climate change on Sunday at the association's annual meeting in San Francisco. The statement, the first on global warming by the AAAS, was featured in an article, "Scientist Group Warns of Warming 'Threat'", on the back page of the WaPo A-section yesterday.

Also at the annual meeting, AAAS President John P. Holdren strongly urged scientists and engineers to become personally involved in working to find solutions to the challenges posed by "poverty, climate change and nuclear proliferation." His call to "tithe" 10% of their time "to working to increase the benefits of science and technology for the human condition and to decrease the liabilities" was received with a standing ovation.


Dave Statter's WUSA-TV report of vehicles spinning out of control on untreated Lee Highway in Rosslyn Sunday night was featured prominently and repeatedly on the Weather Channel's Evening Edition last night.

Seasonal Outlook

Latest seasonal forecast: Click here.

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