Friday, February 2, 2007

Another Arctic Attack Approaching


Mixed precipitation showers, cold. Some leftover moisture and energy from yesterday's non-event was being swept over the Washington metro area today ahead of a cold front moving eastward from the Ohio Valley. Showers of mixed precipitation type were falling through temperatures mainly in the mid and upper 30s. The next Arctic attack, now massing on the Canadian border, will sweep into the area over the weekend, setting the stage for what promises to be the most frigid week of the season so far.

Tonight and Tomorrow

Showers/flurries ending, clearing, breezy, cold. Scattered showers and snow flurries will end this evening, with cloudiness decreasing by morning. Lows will be in the mid 20s in the city, near 20° in the 'burblands. Tomorrow will be partly cloudy, windy, and cold, highs near 34°.

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

Climate Corner

The release of the first volume of the IPCC Fourth Assessment Report this morning was widely covered in the world press. Among at least 1000 others, articles appeared online in the WaPo, NYT, ChiSunTimes, BoGlo, USAT, and Miami Herald. The package of articles at the UK Guardian was especially comprehensive. A pdf file (about 2.3MB) of the report and the webcast of the announcement are available online. has started a thread for discussion of the report.

Bob Ryan had a short, but effective, interview on the subject last night with Ralph Cicerone, who is President of the National Academy of Sciences here in Washington. Imagine that: a broadcast meteorologist actually consulting a real climate scientist, an "atmospheric scientist whose research in atmospheric chemistry and climate change has involved him in shaping science and environmental policy", instead of promoting radical right radio rhetoric. One of Dr. Cicerone's comments should be listened to carefully by Bob's more paranoid broadcast brethren: There will still be jobs for operational forecasters, even with global warming!

The belief tanks, of course, have geared up for attack mode in response. If you want to keep score at home, the droll Prof. Rabett has devised a version of Global Climate Denialist Bingo. Get 4 hits in a row and win a prize! In addition to his political role, Benjamin Franklin was one of the founders of American scientific meteorology, so it's only fitting that the denialists are putting their money where their mouths are and offering 100 Benjies for attacking the IPCC.

Thursday, February 1, 2007

Snowstorm Suppressed South


Cloudy, cold. "Do your homework, boys and girls." (Bob Ryan, 11pm last night) Fortunately or frustratingly, depending on your position on the Washington snow spectrum, light snow slid off to the east today south of a line from just south of Charlottesville to near Ocean City. The precipitation was associated with an Atlantic coastal front northeast of a weak low pressure area having trouble getting organized along the Gulf coast. This low is expected to develop more off the Carolina coast tonight, taking the main body of precipitation away with it south and east of the Beltway.

Little, if any, frozen accumulation is likely. The team will continue to monitor the situation and post a mid-evening update if conditions warrant.

Surface weather map at 1pm today from HPC/NCEP/NWS shows . . . not a lot going on in the Mid Atlantic area

Tonight and Tomorrow

Mostly cloudy, cold, some light precipitation, mostly to the south and east. Skies will remain mostly cloudy overnight with some light snow or mixed precipitation developing after midnight, mainly to the south and east of the immediate metro area. Lows will be in the low 30s. Clouds will linger through most of tomorrow as the next Arctic attack approaches, with a chance of some showers or snow flurries in the afternoon or evening. Highs will be near 40°, but turning colder late in the day.


A trace of precipitation was recorded today from very widely scattered snow flurries in the metro area. Perhaps the site visitor who criticized Bob Ryan's long and distinguished career yesterday would like to reconsider those remarks. Bob's 11pm forecast of flurries or a dusting at most was definitely more accurate than the one on a certain HDTV news broadcast.

"Sometimes a cigar is just a cigar." (S. Freud) The reason the models have had a hard time getting a handle on this system is simply that there hasn't been much to get a handle on. The much-maligned NAM model has been hinting at a southern suppression of the precipitation since at least yesterday at this time, however. This afternoon's models continue in that direction.

Capital Climate

"This generation has altered the composition of the atmosphere on a global scale through . . . a steady increase in carbon dioxide from the burning of fossil fuels." (Al Gore? Heidi Cullen? Union of Concerned Scientists? No, President Lyndon Johnson in 1965.) Naomi Oreskes, professor of science history at UCSD and author of an important survey of scientific consensus on global warming, has an op ed piece, "The Long Consensus On Climate Change" in today's WaPo tracing the more than century-long history of scientific concern with greenhouse gases' effects on climate.

Set your clock radio: The release of the IPCC Working Group I report will be webcast tomorrow from Paris at 3:30am Washington time.

Wednesday, January 31, 2007

Upcoming Storm: A Mix, a Mess, or a Miss?


Clear, seasonably cold. January is closing out the books on a cold note in the Washington metro area, with afternoon temperatures reaching only the low and mid 30s despite abundant sunshine; highs were 34° at National, 33° at Dulles and BWI. A storm system just beginning to organize itself along the Gulf Coast will bring increasing cloudiness and some wintry precipitation into the picture for tomorrow into Friday.

Tonight and Tomorrow

Increasing clouds, cold, some snow likely developing. Clouds will increase tonight with lows in the low to mid 20s. Tomorrow will be mostly cloudy in the morning with some snow likely developing in the afternoon, highs around 35°.


Not a lot has changed since Dan's early afternoon update, so I won't repeat his post. The latest models have continued to support the notion of a storm track suppressed to the south of the Mid Atlantic area. Although there are some differences in the intensity of the storm development, both major U.S. models keep the heaviest precipitation from central and southeastern Virginia southward, where it would be mostly in liquid form. At this point, the observed storm system is extremely weak, and the models don't provide a lot of upper air energy support, so any major development is likely to take place well offshore, after precipitation has ended in this area. We're adjusting our snow accumulation potential chart to reflect the likelihood of lower amounts.

For the details of the rest of the week and the Snow Lover's Crystal Ball, scroll on down to Dan's post below. chart, photo © Kevin Ambrose


Reliable sources tell us Larry King (CNN, 9pm) is scheduled to be focusing on climate change tonight. Expected guests: Inhofe, Boxer, Cullen.

Capitol Climate

Yesterday's House and Senate hearings on global warming policy were reviewed in a WaPo article today, "Lawmakers on Hill Seek Consensus on Warming". PM Update's favorite quote, from committee chairman Waxman: "All of us have a right to our own opinions as to the seriousness of global warming. We don't have the right to our own science."

Also covering the subject, among about 550 others, were the SF Chron, AP (via BoGlo), NYT, ChiTri, LATi, UK Guardian, Reuters, and the Financial Times.

Tuesday, January 30, 2007

A Flurry of Interest


Variable cloudiness, seasonably cold. Southerly winds ahead of a "clipper" low pressure system moving eastward from the Great Lakes have pushed temperatures into the seasonable lower 40s this afternoon, despite considerable cloudiness at times. A band of snow showers extending from just north of the Mason-Dixon line southwestward to the West Virginia panhandle gave a trace of precipitation to Hagerstown and was moving into Frederick at mid afternoon. This band is likely to provide some scattered flurries to the Washington metro region, especially the northern portions through Baltimore and northeastern Maryland. A new cold shot will follow tonight into tomorrow, with the likelihood of some mixed precipitation later in the week.

Tonight and Tomorrow

Scattered flurries, turning colder. After a 30% chance of snow flurries through this evening, skies will clear later tonight with lows in the low 20s downtown to the upper teens in the 'burblands. Tomorrow will be mostly sunny with highs in the mid 30s.

Looking Beyond

This afternoon's models, while still waffling on the details, are confirming the likelihood that a projected storm for Thursday into Friday is likely to be a mixed precipitation event, with some accumulation of snow and ice possible. The exact track and precipitation amounts from a storm which doesn't yet exist have varied from run to run, but one factor which has been quite consistent since at least late Saturday is the lack of a mechanism to hold enough cold air in place and in enough depth for a significant all-snow event in this area, although some might consider any measurable amount to be significant at this point in the season. (For the model-watchers out there, don't forget when looking at a 2-dimensional map that the atmosphere is a dynamically evolving 3-dimensional compressible fluid. Just reading off green shading and red and blue lines at a point in time doesn't give the whole picture.)

For the details of the rest of the week and the Snow Lover's Crystal Ball, scroll on down to Jason's post below.

Capitol Climate: "Atmosphere of Pressure"

The House Oversight and Government Reform committee hearing on government climate science integrity opened this morning with a bipartisan complaint from both Chairman Waxman and Ranking Member Davis of Virginia that the Administration did not fully comply with the committee's request for documents. C-SPAN cut away from the hearings for the House session, but promised to broadcast the hearings later; check your listings. The prepared testimony from the witnesses is posted on the committee web site.

On the Senate side, the Committee on Public Works held a hearing today to provide a "Senators' Perspectives on Global Warming". Twelve Senators were confirmed to present their views on the subject.

C-SPAN-3, the "Oldies Channel", is scheduled to re-broadcast several old speeches and hearings on climate change, beginning tonight at 8:00.

Monday, January 29, 2007

Watching a Wintry Washington Week


Sunny, cold. A weak low pressure wave which gave some scattered snow flurries to the region yesterday, mainly to the east of the metro area, deepened rapidly well offshore to help pump in colder temperatures today. Readings struggled to reach freezing in most locations with a brisk northwesterly breeze; highs were 33° at National, 32° at Dulles, 31° at BWI.

The month has now dropped out of the top 10 warmest Januaries. As Jason has already noted, this week is likely to be the coldest so far this season, with at least one chance of some wintry precipitation later in the week.

Surface weather map at 7am today from HPC/NCEP/NWS shows a deep low off the Atlantic coast

Tonight and Tomorrow

Mostly clear and cold, then slight chance of flurries. Tonight will be mostly clear and cold with diminishing winds. Lows will be near 20 in the city to the mid teens in the 'burblands. Tomorrow will be partly cloudy and continued cold with a 30% chance of snow flurries, mainly late in the day, highs near 37°.

For the outlook through the rest of the week and the Snow Lover's Crystal Ball, scroll on down to Jason's post below.

Capitol Climate

The House Oversight and Government Reform committee is holding a hearing tomorrow "regarding political interference in the work of government climate change scientists." The witness list includes a NASA scientist, a former staff member at the U.S. Climate Change Science Program, the Director of the Scientific Integrity Program of the Union of Concerned Scientists, and science policy researcher Dr. Roger Pielke, Jr. of the University of Colorado. Montgomery County Congressman Chris Van Hollen is a member of the committee.

Seasonal Outlook

Latest seasonal forecast: Click here.

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