Where will February 2007 rank?

At the halfway point of February 2007, the temperatures departures are quite impressive. Bowling Green is at -9.2 F, Louisville is at -12.3 F, and Lexington is at -13.6 F. Using the latest 7-day forecast from the NWS, by February 21st, the departures for the month should be Bowling Green at -9.2 F, Louisville at -12.1 F, and Lexington at -13.3 F with only seven days left in the month. So what can we expect for the last week of February? Even with a warmup, where will February 2007 rank among the all-time coldest?

Both the 6-10 day and 8-14 day forecasts show that Kentucky and the rest of the eastern U.S. will warm to above normal levels during the last week of the month. This is because the polar vortex which has tormented the eastern U.S. since mid-January will finally retreat back to the Yukon by the middle of next week. This will produce a more zonal (west to east) flow in the upper levels of atmosphere which will allow milder Pacific air to surge across the country. However, the cold air will not be far to the north, so any disturbance in the flow may allow a return of Canadian air across the country. Therefore, I think it is safe to make a prediction that the last week of February may average out somewhere around +4 for the state (Highs upper 50s, lows mid 30s).

When a week of +4 anomalies are averaged in with the three weeks of very cold anomalies, the averages for the month should be around -5.9 F for Bowling Green, -8.1 F for Louisville, and -9.0 F for Lexington. Aggregating the departures for the various cities into climate divisions would produce a departure from normal of roughly -7 F for climate division 2 (Bowling Green and Louisville) and -9 F for climate division 3 (Lexington). For CD 2, the February normal is 37 F, which means that the monthly average of 30 F would be the coldest since the bitterly cold winters of 1978-1980, which averaged 23.6, 29.0, and 30.2 respectively. A climate division average of 30.0 would rank it near the 10 coldest Februarys since 1895.

For climate division 3 (Bluegrass), the historical February average is 35 F, so a departure of -9 F would produce an average of 26 F for the month. This would also be the coldest since the 1978-1980 time period, but the larger departure would put the month between the 5th and 10th coldest Februarys since 1895.

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