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Chicago - Do not adjust your calendar. This is December but often times this month it has felt more like spring that the start of winter. Tuesday will be our 6th straight day with above average temperatures and this streak should easily stretch to nine days by the end of this week. Record highs on both Wednesday and Thursday are within reach. We are running about 6° above average so far this month. The average temperature for the month is closer to what we expect in March than December.
O'Hare has reported a trace of snow four times this month but we have yet to have measurable snow (.1" or more). We have less than a week to go before possibly setting a new record for a lack of snowfall. The latest we have gone into the season without measurable snow is December 20th (2012). No significant snow but we have had a rare tornado in the Chicago area this December. The tornado touched down on Friday night in Crown Point and traveled nearly five miles to Crown Point before it lifted.
The Chicago office of the National Weather Service puts the rarity of this event in perspective:
- The first December tornado since 12/4/1973, and only the 4th tornado to occur during the month of December
- The latest tornado on record in a calendar year. The other three happened on 12/3/1955, 12/8/1966, and 12/4/1973.
Friday night's tornado touched down just after 10 pm in Cedar Lake and remained on the ground for nearly five miles before lifting in northern Crown Point. The peak winds reached 75-85 mph and the maximum width of the twister was 100 yards. No deaths or injuries but some minor damage was reported that included several downed trees. There were also reports of moderate roof damage.
The severe weather that impacted the area Friday night is something seldom seen this time of year. Only .7% of all 1220 severe weather days in the past 61 years have occurred during the month of December. Just 9 days of severe weather have occurred during December since 1950.
Even though it is rare this time of the year, Friday night's tornado is a reminder that severe weather can occur during any month. While the greatest number of tornadoes have historically struck during the spring and summer months, we can't let our guard down outside of the traditional severe weather season window.
Rare warmth for December is expected both Wednesday and Thursday when record highs are within reach. The record for Wednesday is 64° set in 1971 and the record for Thursday is 60° set back in 1984. The GEFS forecast of daily highs and lows has us soaring to 63° on Wednesday (my forecast high is 64°). It might be near 60° just after midnight Wednesday so the high for Thursday will be reached early Thursday morning before temperatures fall into the 40s by the afternoon. There is potential this week for two days with a high of 60° or more. That is remarkable when considering there have only been 77 total days with high of 60° or warmer during the month of December since records began here in 1871.
There is still hope for fans of typical wintry Chicago weather. In the span of about 30 hours we will go from near 60° early Thursday morning to possibly the upper 20s just before daybreak Friday morning. There is also a chance for a little light snow Friday night into early Saturday. Hang in there!