As a shortwave lifts from the Southern Plains toward the Great Lakes on Monday, an attendant surface low should track from across eastern Arkansas toward Indiana during the daytime. Due to the proximity of the surface low and stronger pressure gradient, expect the potential for gusts around 25-30 mph during the morning and early afternoon – especially through the Delta region. Some stronger gusts may be possible.
This area of low pressure will bring a cold front through Mississippi through the afternoon and evening on Monday. Models continue to indicate modest instability across the warm sector, which will become increasingly surface- based during the day on. Strong deep layer wind shear will be in place, so storms which do develop will have the chance to become strong to severe.
With weaker low-level lapse rates in place, any severe storms will likely be confined to near the cold front where bowing segments will pose a damaging wind threat and isolated tornado threat. Based on the current expected timing and strength of low- level warm advection, the Marginal Risk for severe weather has been expanded a little farther west to encompass all of our Mississippi counties as well as portions of far southeast Arkansas and northeast/central Louisiana.
The chance for thunderstorms should quickly diminish after sunset on Monday as everyone prepares to ring in the New Year, however, a chance for showers may linger through southeast and eastern Mississippi into the overnight hours. The front does not look to push too far away from our area, so better rain chances return once again by Tuesday night into Wednesday as over-running moisture will spread rain chances inland. Model guidance continues to struggle with resolving the energy in a trough sweeping across the country in the middle of the week, so there is still lower confidence with regards to temperatures and precipitation type for our northern counties.
If the trough remains a mostly open wave as it passes, expect precipitation to end before any colder temperatures can work into our northernmost counties. If some portion of the trough can close off and deepen as it passes, there may be a chance for some precip to fall in the colder air and produce some wintry precipitation in our northeastern counties.
So, I will mention light rain or light snow for parts of northern Mississippi Wednesday night into Thursday morning, with no accumulations currently expected. Would not be surprised for some sleet to mix in either, due to marginally conducive mid-level thermal profile. Will continue to re-evaluate this system as well as the trough takes shape across the Inter-Mountain West this week. Regardless, the trend for temperatures will be toward cooler for Wed-Fri, with a gradual warming trend heading into the weekend as an upper-level ridge moves east toward our region.
Hattiesburg, Mississippi Extended Forecast:
