Today's Weather Discussion: Calm & Chilly
Wednesday, Dec. 1:
Good Wednesday, and happy first day of "meteorological winter"! You may have heard me reference that today on Local 6 Midday and wondered what I was talking about. Obvious, this is different that astronomical winter, which arrives on Dec. 21 and is based on the position of the sun relative to the earth's orbit. Basically, this is a method used by meteorologists of determining seasons based on the dominant weather conditions of the period. Since December, January, & February are the 3 coldest months of the year, we lump those months together as "winter".
Looking ahead to this month, the latest monthly outlook includes equal chances of either above or below average temperatures and precipitation. Average highs for the month range from 51 degrees on 12/1, to 43 degree on 12/31. Average lows range from 32 on 12/1, to 24 on 12/31. Average precip (rain & melted snow) for the month is 4.37". We'll see what happens, but for now, a very usual month seems likely. For more on the monthly forecast from the NWS/NOAA, click here.
On to the forecast....chilly but calm seems to be the going theme for the next week or so. We'll be affected by a couple of minor disturbances, but nothing too significant to worry about. High pressure building in today will make for clear skies and cold temperatures tonight, with increasing clouds overnight.
Thursday's weather will be highlighted by an "Alberta clipper" type system....an area of low-pressure/cold front that develops over southern Canada (Alberta) and quickly dives southeast through our region. (Click here for more info about Alberta clippers.) These systems are characterized by fast movement, a drop in temperatures, and lack of precipitation....all part of tomorrow's forecast. Ahead of this system, clouds will be increasing. Below is a look at a forecast model image for 6AM Thu. that we use when forecasting cloud cover and precip chances. The image depicts the relative humidity in the lower and mid layers of the atmosphere....where you see shades of purple, that represents dry air (and most likely clear skies....where you see shades of blue, that represents higher relative humidity, and thus a greater coverage of clouds.
As you can see, we'll be expecting clouds to increase by daybreak, with partly sunny to mostly cloudy skies for much of the day. There could even be some sprinkles or flurries around I-64. The cold front associated with this system isn't expected to arrive until tomorrow night, so southwest winds during the daytime will help temperatures into the upper 40's. Tomorrow night though, behind the front, lows will again plunge into the 20's.
Another clipper heads this way Friday night & Saturday, with another increase in clouds and chance of sprinkles, followed by chillier temperatures Sunday, Monday, & Tuesday. I have been watching a trough of low pressure that is expected to arrive on the west coast by late Sunday. I didn't want to cause a stir over the weekend, but a few days ago this system looked like it would pose a threat for some wintry weather for us. However, models have been showing a fairly consistent signal for a few days now that the system will stay closer to the Gulf coast. It's not totally out of the question that we may see a few snowflakes on Monday, especially across the MO Bootheel and NW TN.....but for now, it looks like a big dome of high pressure will keep things dry and quite cold for the beginning of next week.