Tuesday, November 1, 2005

Nice November Start

High, thin clouds ahead of a weak cold front are keeping November 1 from being quite as spectacular as Halloween, but it's a nice start to the new month. Temperatures around the Washington DC metro area are in the range of upper 60s to 70. Showers associated with the front, a few of them moderate, were making their way at mid afternoon from just past Pittsburgh to Morgantown, WV and across western West Virginia.

Regional radar image at 3:53pm from The Weather Channel.
Today's forecast problem is not earth-shattering, but it does illustrate one of the classic dilemmas in forecasting for the Nation's Capital: Will it rain tonight as the cold front moves through? On the one hand, the models are remarkably low in their "POPs" (probabilities of precipitation). One of them, the "NAM", keeps the POP no higher than 8% through tomorrow morning. The latest model run, from data collected at 1pm this afternoon, brings light precipitation (up to 0.10") about halfway across Maryland before drying it out. The National Weather Service forecast discussion this afternoon says, "The models have been pretty consistent bringing this boundary through with very little measurable precip and rapid drying behind the boundary." On the other hand, there is the "look out the window" (or at least the Doppler radar screen) factor. The line of showers is quite respectable-looking, and it has already brought about 0.1" to Pittsburgh. There is, however, the matter of those pesky mountains between there and here which often break up the precipitation before it can reach the metro region.

My bottom line is: The long-term average number of days with measurable precipitation in November is the third lowest of the year at 8.5, but this is still 28%. The current situation is at least as likely as any random November day to produce precipitation. Therefore, I would have to say that the probability of precipitation is 30% tonight, rather than ruling it out, as the official forecast does. The caveats are: Any rainfall will be very light and scattered, and it is more likely to the north and west of the immediate metro area.

Tonight and Tomorrow

Tonight will be mostly cloudy with a 30% chance of light and scattered showers, lows near 49. Tomorrow will be sunny and a little cooler with highs in the mid 60s.

Tropical Beat

The tropics remain relatively quiet. There are several tropical waves across the Caribbean and Atlantic, but none of them are showing signs of development.

Broadcast News

I accidentally came across some nice hurricane video on NASA TV this morning, but it's not listed in the schedule. If you're flipping channels, you might want to look for it (channel 21 on Comcast Montgomery analog).

The NASA hurricane web page has an animated depiction of the 2005 hurricane season from Arlene through Wilma, including sea surface temperatures, clouds, and storm tracks. I didn't have time for the 2-hour download, so if anyone looks at it, please let us know in the comments how it looks.

WETA, channel 26, is broadcasting "Global Warming: The Signs and the Science" tomorrow night at 8:00. The show is hosted by Alanis Morissette; it "profiles people who are living with the grave consequences of a changing climate, as well as the individuals, communities and scientists inventing new approaches." A 2-minute preview is available to download.


The Weather Man movie got 2 Thumbs Up® from Ebert and Roeper last weekend. As Jason pointed out in his review below, it's not about meteorology; the science is somewhere between negligible and nonexistent.

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