Thursday, February 2, 2006

Round Rodent vs. Regression

Happy Groundhog Day! Even the most diehard snow fan must admit that temperatures pushing toward 60°, and even above on the southern fringes of the region, can't be all bad on the 2nd day of February. Meanwhile, unless you've been totally isolated from all media, you know by now that our Phurry Phriend Phil has done his duty for another year by seeing his shadow and predicting 6 more weeks of winter.

Regional radar is mainly clear as clouds gradually increase from a developing low pressure area moving northeastward from the Gulf states. Some widely scattered showers have reached into West Virginia and southwestern Pennsylvania. This low will bring some rain to the area overnight. Current indications are that the next system may end as some wet snow or flurries on Sunday, with little or no accumulation in the immediate area. The models are becoming more consistent on this, but there is still some difference in timing.

Tonight and Tomorrow

Clouds will increase this evening, with showers beginning around 1am and lows in the mid 40s. Showers will end in the morning tomorrow, with some sun in the afternoon and highs in the upper 50s.

Snow Statistics

A couple of weeks ago, we noted that, statistically at least, January snowfall gives virtually no clue to February's amount. Today's chart shows that there is one element which does provide some insight, and that is February temperature. Colder temperatures do correlate to some extent with more snow. As some site visitors have pointed out in earlier comments, however, this is far from a lock. There is a lot of scatter in the data, and some quite cold Februaries have had little or no snow, even a few which averaged below 30° (13° colder than this January).

The dashed regression line shows that for each degree the monthly average temperature is below about 44.1°, the expected monthly snow total increases by about ¾". The value of R² indicates that about 25% of the variance in snow amounts is accounted for by the average temperature. chart from NWS data

DC Comics

Tom Toles' cartoon in today's WaPo commenting on political science:

Seasonal Outlook

Latest seasonal forecast: Click here.

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