Friday, February 24, 2006

Ice Guys ISO . . . Winter

This winter's underperformance reduced the discussion in the Comments section last night to the subject of blog ads. However, a brisk cold front which brought thundersnow to Syracuse NY and a few other places in New York and Pennsylvania has brought Washington DC metro temperatures to below seasonable levels this afternoon.

It's also very dry. Dewpoints as low as the single digits correspond to relative humidites in the 20s. Along with northwesterly winds gusting over 30 mph, this has prompted the National Weather Service to issue fire weather watches in the area for the next several days. After a quick temperature rebound upward tomorrow, a stronger shot of cold will arrive on Sunday.

As the chart shows, however, the trend may be favorable for the snow lovers, but the calendaricity is not. Taken literally, the trend so far this month would take us to an average high in the mid 30s by the end of March. Like so many other trends here in the Nation's Capital, this trend is not sustainable. chart from NWS data, photo © Kevin Ambrose

Tonight and Tomorrow

Lows tonight under scattered clouds will be from 28 in the city to the low 20s in the colder 'burbs. Temperatures should bounce back to the mid 50s tomorrow before the next cold front arrives to lower them significantly on Sunday.

Video on Demand (or Not)

The current issue of PC Magazine has a review of the new Flash-based WeatherBug VideoCast. It gives you a forecast tailored to your zip code and delivered by your choice of 3 broadcasters.

The Richmond Times-Dispatch has more background information on Roanoke weatherman Marc Lamarre's drug problems.

Thursday, February 23, 2006

Transitional Thursday

Yesterday's light snow is but a memory in the Washington metro area this afternoon, although I can still see some scrapings from my front walk basking in the strong late February sun. Temperatures were in the low 50s throughout the region by mid afternoon. Earlier, a minor area of upper-level energy passing through created the instability which produced a few briefly moderate showers, particularly in northern Montgomery County.

Geese enjoying the course at the Hidden Creek Country Club in Reston, VA, yesterday afternoon. Photo © Kevin Ambrose,

Winds have picked up from the west and northwest, gusting as high as 32 mph. Temperatures should be near seasonable levels for the next 24 hours before dropping over the weekend as the northern branch of the jet stream regains dominance over the eastern part of the U.S. (See Josh's post below for the extended-range details.)

Tonight and Tomorrow

Skies will be mostly clear tonight with lows around 30. Tomorrow will be sunny and cooler with highs near 46.

Political Science

The Council of the American Meteorological Society adopted a statement on "Freedom of Scientific Expression" last week. It states in part,
The ability of scientists to present their findings to the scientific community, policy makers, the media, and the public without censorship, intimidation, or political interference is imperative.

Weather Addiction

We already knew that weather can be addicting, but this is taking it to the extreme: The Roanoke Times, via the dcrtv blog, reports that two Roanoke TV weathermen have been struggling to deal with heroin addiction. One of them, Marc Lamarre, is no longer employed by the station, WSLS (Channel 10).

Wednesday, February 22, 2006

Nothing to See Here, Move Along

Well, that was certainly exciting. We actually saw some of that white stuff in the Washington area this morning, you know, what do you call it? Oh, yeah, I think it's coming back to me now: snow. In the snow-starved Washington region, what was nearly a meteorological non-event created a bit of a buzz among the snow fans. If you were stuck in one of the backups reported on radio and TV along I-270, the Beltway, I-66, or the Dulles Toll Road, you have my profound sympathy. Please don't blame the weather for the effects of your fellow rudely aggressive drivers, however. They can turn even the sunniest Monday holiday into a commuting disaster.

American Legion Bridge on President's Day, photo from TrafficLand via WTOP

Arriving a few hours ahead of schedule from yesterday's PM Update forecast, a weak disturbance racing eastward to the south of the area left mostly under an inch of slushy snow on some grassy and elevated surfaces in the metro area. Light rain which began at Washington National at 6:17 became mixed with snow by 9:15 and changed to light snow for about an hour before ending at 10:45. Total precipitation: a tad under ¼". A similar amount was reported at Dulles, where the precipitation was all snow, occasionally moderate, after a few minutes of rain at the beginning. By early afternoon, some drizzle and fog was being reported around the area.

Now you see it, now you don't: Regional radar to the right from The Weather Channel shows snow falling in most of the metro DC area at 9:38 this morning. An hour and a half later, it's all rain, some moderate, on the Eastern Shore back across the Bay to the Northern Neck.

As for the forecasts, you can scroll on down and make your own judgment. Personally, I think we did pretty well, along with the TV forecasters I saw last night (Sue Palka on 5 and Topper Shutt on 9) and the National Weather Service. (FWIW, the Weather Channel Local on the 8s was still predicting a 40% chance of snow at noon today in Montgomery County.) Take my word for it, boys and girls, I've seen enough decades (yes, that goes back close to half a century) of busted DC snow days to have not gone out on any more of a limb than I did 24 hours ago. The vast majority of these weak systems fall apart crossing the mountains or move just a little too far north or south to be of any consequence to our area.

In fact, I'm very impressed that the current generation of high-resolution numerical models was able to pick up anything at all with this system. If you looked at the surface weather map about 18 hours before the event, I don't think you would have seen any signs of precipitation to occur here. To see the entire sequence of maps at 6-hour intervals through this afternoon, click here, here, here, and here.

Another wave moving along that pesky front hanging around the Carolinas could bring us a similar event tomorrow, but as of now the indications are that any precipitation will stay mainly to the south of us. Once again, temperatures will be marginal, but cloud cover overnight will keep readings above freezing in most places.

Tonight and Tomorrow

Areas of fog and drizzle will persist through this evening. Tonight will remain cloudy with lows in the low and mid 30s. Tomorrow there is a slight chance of light rain or mixed rain and snow in the morning. Clouds will decrease in the afternoon with highs around 49.

High-Def Open Mike

Overheard this morning when the studio audio was inadvertently left on during Local on the 8s on The Weather Channel was Kristina telling Kevin, "'CNN buys new line of high-def makeup.' . . . I'm really not looking forward to that day."

Tuesday, February 21, 2006

Zoning Out

It was exciting while it lasted, but the dip in the jet stream which brought Arctic air into the Washington DC area over the weekend has been replaced by more "zonal" (east-west) flow. The chart to the right shows the 500 mb height (approximately the middle of the atmosphere) over North America this morning. The colors represent areas of roughly equal height, and the solid lines are the barometric pressure at the surface.

The milder temperatures have reached above the long-term average, nearing or hitting 50° by mid afternoon throughout the area with westerly and southwesterly breezes. Despite the 17° departure below "normal" on Sunday, we are still nearly 2° above average for the month so far. A weak disturbance moving eastward south of the area will bring the threat of light precipitation tomorrow afternoon, mainly rain through central Virginia and some mixed rain and snow to the north.

Graphic from Unisys

Tonight and Tomorrow

Clouds will increase tonight with lows near 32 in the city and upper 20s in the colder 'burbs. Tomorrow will be cloudy with a 40% chance of light precipitation by late morning or early afternoon, mainly rain with some snow possibly mixed in to the north and highs in the mid 40s.

"In Life, Accuracy Counts"

It's not really about weather, but the "Weather Man" movie (2 Thumbs Up®) is out on DVD today. The movie, which is rated "R", stars Nicolas Cage as Chicago weatherman David Spritz, whose "professional successes are overshadowed by his personal failures." The DVD bonus features include:
  • Extended Outlook: The Script
  • Forecast: Becoming a Weatherman
  • Atmospheric Pressure: The Style and Palette
  • Relative Humidity: The Characters
  • Trade Winds: The Collaboration

Seasonal Outlook

Latest seasonal forecast: Click here.

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