Monday, January 8, 2007

Blast From the Past


Sunny, breezy. Temperatures have been falling slightly this afternoon under northwesterly winds gusting over 30 mph at times, but the main change has been in the humidity. While the temperature fell 1° in 6 hours from 9am to 3pm, the dewpoint plunged from 50° all the way to 22° (and 4 more degrees in the next hour). In the meantime, the high for the day reached 56° early in the afternoon.

While dropping only to near average January levels, temperatures in the next couple of days will seem especially cold after the warm spell we've been experiencing. There is even the possibility of some scattered flurries to go along with the more wintry temperatures.

Tonight and Tomorrow

Clear, cold, flurries possible. Under clear skies tonight, lows will range from the low 30s downtown to mid and upper 20s in the 'burbs. Tomorrow will be partly cloudy and seasonably cold, with highs near 44°. There is a 30% chance of some light snow flurries or sprinkles, especially in the afternoon.

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

Reasoning By Analogy

Analogies are always imperfect, so forecasting from past analogs is a lot like driving while looking in the rear view mirror. Nevertheless, looking at past patterns can provide what the math guys call an "existence proof" and therefore give some clues as to which of the infinite number of possible states of the atmosphere are "preferred." The recent pattern of an upper-level low pressure trough in the West and a high pressure ridge in the East is similar in a lot of ways to the pattern of January 1950, which was by far the all-time warmest January in the 130+ years of official records in Washington. The monthly average of 48° that month was more than 1° higher than the second highest January in 1932 and more than 4° higher than the third place holder, 1890. January 1950 was responsible for 5 daily temperature records which stood until this year. The record for the 6th is the one which was broken on Saturday.

The chart shows the daily highs and lows for January 1950, along with the trend of the month-to-date average for that year and the average for this year so far. Note that after building warmth in the first week, January 1950 went through a series of progressively cooler cycles through the second and third week, finally culminating in the all-time warmest Washington January day, 79° on the 26th. That day was so spectacular that it got its own article in the Monthly Weather Review. The pattern finally broke down during the middle of February. chart from NWS data, photo © Kevin Ambrose

Mediarology: Capitol Climate

Today's Diane Rehm Show on WAMU (88.5 FM) featured a discussion of the prospects of climate policy action in the new Congress. Guests were: John Fialka, environment and energy reporter for "The Wall Street Journal"; Felicity Barringer, reporter, New York Times; Sen. Jeff Bingaman, (D-NM), new chair of the Senate Energy Committee; James Connaughton, chair, White House Council on Environmental Quality. Streaming audio is available online, and the show is scheduled to be rebroadcast tonight at 9:00.

Also from NPR were reports yesterday on the impact of this winter's temperatures on central Maine and an interview with Robert Henson, author of "The Rough Guide to Climate Change".

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Seasonal Outlook

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