A very active weather pattern will impact much of the country through Christmas Day. While the west will see rain and snow, the east will see rain and severe weather, including an increased threat of tornadoes on Wednesday in the Lower Mississippi River Valley as well as the Tennessee Valley.
The weather surface map for this evening shows several fronts and low pressure systems across the country.
For the western US, upper level energy and moisture will continue to funnel into the region allowing for rain and snow to continue especially in the Pacific Northwest and the Intermountain Rockies. Winter Weather Advisories and Winter Storm Warning are in effect for areas with higher accumulations expected.
The graphic below highlights areas that may see at least 8 inches of snow through Thursday Evening.
For areas in the Southern Plains, Severe Weather and heavy rain is the main focus. The NWS Storm Prediction Center has outlined parts of Texas, Oklahoma, Louisiana and Arkansas with a Slight risk for severe weather tonight. The main threat is damaging winds and large hail however an isolated tornado is possible. The thunderstorms are expected to develop late tonight and continue into the early morning hours.
Mississippi and Tennessee River Valleys
The severe weather threat will increase as it shifts east into the Lower Mississippi River Valley for Wednesday. The risk for tornadoes is higher as the atmosphere has a significant amount of energy which will be further fueled by the much above normal surface moisture and temperatures. The areas outlined as “Enhanced” in the NWS SPC day 2 outlook below indicate regions of higher concern which includes Little Rock, Memphis and Nashville. While activity will likely be ongoing Wednesday morning from the storms tonight, the timing for the increased threat of severe weather and tornadoes comes together around midday in Arkansas and Louisiana. The storms will move into the Tennessee Valley Wednesday afternoon with the eastward push of cold front.
While most people might think the first day of winter means the end to severe weather, actually severe weather is not abnormal in the winter months, especially in Dixie Alley. The graphic highlights areas that in the past 30 years have historically seen tornadoes on this day. In fact, in 2012 a tornado outbreak occurred on Christmas Day. The NWS Jackson Office has a write up of this event.
The other side to this story is the copious rainfall that will fall across much of the country through the end of the week. The first graphic below outlines precipitation totals through Thursday morning. The second graphic shows the five day rainfall totals through Sunday morning. So once the system that is triggering severe weather tonight and Wednesday moves east, the system impacting the Pacific Northwest will move into the central and eastern part of the country in time for Christmas Day and the Holiday Weekend. With widespread Rainfall totals of 2 to 4 inches, some areas will have areal and localized flash flooding.
Christmas Day Temperatures
Finally, for a quick glance at the temperatures for Christmas Day, the much above normal temperatures will continue for the eastern 2/3rds of the country. Many areas in the central US will be 10 – 15 degrees above normal while much of the south and east will be 15 to 20+ degrees above normal. For the Rockies and West, below normal temperatures will be the rule.
With the treat of tornadoes, double check your supplies in your tornado shelter/safe room. Aso make sure you have a way to obtain storm updates. Also check that you have enough food, water, extra medicines, and etc. especially if you have guests in town. Finally, ensure your guest know where to go in case you have to quickly seek shelter.
With the threat of damaging winds, consider bringing inside any toys, furniture, and outdoor decor and/ or deflating the blow up holiday decorations that may easily be lofted with 58+ mph winds.
For those impacted by the snow, if you are traveling, double check your car safety kit. Ensure that you have extra water and food for your entire family including pets if they are traveling with you.
If you are impacted by heavy rain, be mindful for localized flooding especially in creeks and streams and other low lying areas. Remember do not drive into a flooded roadway. Even if the water is not moving very quickly, you cannot be sure if the road surface is still intact.
The team at WxIntegrations will continue to provide relevant information and resources to help you better understand and prepare by incorporating weather impacts into your planning and response.