October is the start of the secondary severe weather season in Mid-Missouri and for the second weekend in a row, this month is living up to that reputation.
For most of the week, we saw temperatures gradually climbing into the low to mid-70s and then eventually the 80s Saturday afternoon. The warming trend came as southerly winds not only pulled in warmer air from the south, but moisture from the Gulf of Mexico. These are two key ingredients needed to fuel strong storms here in Mid-Missouri. While we remained unscathed last week, this weekend another strong cold front is set to bring the potential for severe weather once more through Saturday night.
A slight risk of severe weather is in place for areas along and west of Highway 63, with a marginal risk extending to areas east of 63. While all modes of severe weather are possible, the greatest threat looks to be damaging winds as the storms track to the east.
A cold front associated with a decent mid-level trough tracking through the Central Plains will interact with low-level moisture and a warm atmosphere. With a freezing level up to 11,000 feet and increasing winds with height, the atmosphere has sufficient fuel for supercells to form. As the cold front tracks through Mid-Missouri, convection along the front is expected to become more linear. This occurs as the front become parallel with the upper level winds and shifts the main threat to damaging winds. As the storms track to the east they will gradually weaken, as the atmosphere becomes more stable and loses what daytime heating we did see today. As the cold front pulls through the region, we'll see winds shift out of the northwest with a return to fall conditions.
With the bulk of the upper level energy to our southwest, the severe threat in Mid-Missouri will mainly be localized to healthier supercells. Areas along and west of Highway 65 are expected to see all modes of severe weather, with the greatest threat being damaging winds and quarter-size hail.
An isolated tornado can't be ruled out, especially embedded in the line where circulation can be found. As the storms march to the east the tornado and hail threat gradually weaken, with winds up to 50 mph and localized flooding becoming the primary threat near Highway 63. This will likely occur as the frontal boundary begins to outrun the storms themselves, rapidly decreasing the severe threat for Mid-Missouri. All of Mid-Missouri will see anywhere from one to two inches of rain, with localized heavier amounts.
Highway 65: Between the hours of 9 and 10PM.
Highway 63: Between the hours of 10PM and 12AM.
Interstate 44: After midnight.
Once storms clear the area, we'll gradually dry out through Sunday. It's following this cold front that we truly see a fall pattern begin to take shape. A series of cold fronts through next week will gradually knock our highs into the 40s and lows into the 30s. By next weekend we will likely see our first freeze of the season, nearly two to three weeks earlier than in the past two years.