Heavy rain and storms Tuesday afternoon and evening. Latest info on flooding and severe storm risk.
A multi-faceted storm system will bring the threat of flooding and severe storms to our area on Tuesday afternoon. The midday update from the Storm Prediction Center expanded the Level 1 of 5 risk of severe storms for Tuesday northward to now include portions of southern middle Tennessee, and it was already covering all of north Alabama and north Mississippi. The higher risk is to our south and southwest, where there is as high as a Level 4 of 5 risk over Mississippi and Louisiana. However, high-resolution model guidance has been trending higher with our instability here locally in the Tennessee Valley, especially south of the Tennessee/Alabama state line, and I think the Level 2 risk may be pulled into northwest AL and northeast MS during the overnight update. The overall timeframe for our local area is roughly from 2:00 PM to 10:00 PM tomorrow afternoon and evening. We will break that down in more detail with Futurecast model imagery in a moment. A few of the storms tomorrow afternoon and evening may produce damaging winds of 60-70 mph, as well as a few tornadoes. Severe criteria hail isn't likely (quarter size or larger) but can't be ruled out completely with any individual storms that may develop ahead of the line. Heavy rain and flooding is an elevated risk, and this may be our larger and more widespread threat.
You can scroll through the Futurecast timeline above for the evolution of the storms. During the morning hours, we expect to have mostly cloudy skies with temperatures starting in the 50s. As we head into the midday, a few showers may work through the area but most folks will stay dry. We actually expect some breaks in the cloud cover to allow sunshine during the late morning and early afternoon. This gets temperatures into the low to mid 70s. As we head into the mid afternoon, we will be watching the potential for isolated individual storms to develop over north Mississippi and north Alabama. IF these form, they have the CHANCE of becoming supercells with a tornado risk. As we head toward 5-7pm, the main line of storms will move into the area from west to east with a more widespread threat of damaging straight-line winds and a few tornadoes. The higher severe weather risk with this line will be on the Alabama/Mississippi side, but we can't rule out isolated severe wind gusts or a tornado in southern Tennessee either. As we head toward 8-10pm, the line will push eastward through the area, but we will begin to lose daytime heating and instability, and although the threat of severe storms won't be zero, it will be on the decrease. By 10pm-Midnight, we likely will have worked over the atmosphere enough that the main threat will have shifted to continued heavy rain and flooding. This transition may even happen a little bit earlier than that, closer to the 8-9pm timeframe depending on the exact evolution of the line of storms.
In addition to the severe storm/tornado threat, flooding is a significant risk. A Flood Watch has been issued for all of northwest Alabama, northeast Mississippi, and southwest Tennessee. It is very possible that southern middle Tennessee could be added to this Flood Watch as well. A widespread 2-3 inches of rain is likely over our area, and some isolated totals could exceed 4 inches. In addition to all that, gradient wind gusts away from the storms tomorrow may exceed 30-40 mph, and a Wind Advisory is in place across north Mississippi and Alabama, and this may be added to middle Tennessee as well.
We will be right here tomorrow and tomorrow evening to provide live coverage should any warnings be issued for our area!