While a white Christmas is always unlikely for our area, a wet Christmas does appear to be in the works. The rain may be the least of our concerns, as forecast models have been consistent for much of the last week advertising an elevated risk for severe thunderstorms.
That risk includes all of the areas within East Mississippi and West Alabama in the Newscenter 11 viewing area. Severe thunderstorms will be capable of producing dangerous tornadoes, damaging wind, and large hail. As of Sunday afternoon, timing looks to be Tuesday late afternoon and evening. Some adjustments in the timing may be necessary since this system is still developing.
Now is the time to review your severe weather plan and make sure your batteries work in your NOAA Weather Radio. Remember, if you do not have a NOAA Weather Radio you can purchase them from Cowboy Maloney's in Meridian as well as Walgreen's in both Meridian and Philadelphia. Be sure your family and any guests from out of town know what to do if severe weather threatens.
Above is the short version. Continue reading for the longer, more detailed, technical version.
Sunday afternoon weather analysis shows us low pressure developing along a cold front along the Red River in northern Texas and southern Oklahoma. The low pressure is moving eastward into an environment that is cool and overall unfavorable for rapid intensification, but the counter-clockwise circulation is drawing moisture off the Gulf of Mexico and bring showers to East Mississippi and West Alabama for Sunday afternoon.
The moisture being brought to our area will linger as this weak low pressure lifts out of our area. High pressure east of us will bring warmth northward from the Gulf. Farther west, surface pressure is already falling east of the Rocky Mountains from northern New Mexico to Southern Colorado. That is the developing system of concern for our Christmas Day weather.
Forecast models indicate a rapidly intensifying storm system over the Plains Monday. Ahead of that system, the warm wind intensifies, helping to destabilize the atmosphere in our area. Forecasts of stability forecasts are unusually intense for this time of year. Combine that high level of instability with strong turning of the lower level wind, and the stage is set for severe weather.
To add more pieces to this weather puzzle, the jet stream may set up in a manner where the upper level wind pattern is diffluent, or spreading out. This pattern will enhance lift and help to sustain thunderstorm updrafts, meaning some of these severe storms could last longer than normal. Longer lasting, spinning updrafts will be very much capable of producing dangerous tornadoes and large hail. This is primarily the case with supercell thunderstorms ahead of the cold front's squall line, which will bring an increased threat for damaging wind in addition to a continued tornado threat.
Model forecasts indicate that as warm air is drawn north into the east side of the low pressure, instability could spike in our West Alabama counties and the intensity of the thunderstorms could erupt Tuesday evening as the storms approach the Mississippi/Alabama line.
This severe risk is highly dependent on the track of the low pressure circulation. Late in the week, some model forecasts suggested a track that kept the low pressure south of us. That track would confine the severe weather threat to the coastal areas of Mississippi and Alabama. By Sunday, most models have trended north with the path of the low pressure, which favors severe weather along and south of Highway 82 (Greenwood to Winona to Starkville to Columbus to Aliceville).
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