Strong to severe thunderstorms are possible as a spring-like weather pattern sets up on Tuesday.
A few scattered thunderstorms are possible late tonight into Tuesday morning as a warm front lifts north, driving in warmer temperatures and more moist air for the afternoon.
Some high-level cloud cover could limit our afternoon heating and ability to break through the "cap" that would keep air from rising and developing thunderstorms. However, several other factors will be present that will help storms to get going by Tuesday evening. Ample wind shear and the strengthening low level jet stream will be positioned right over or just south of our region, allowing for a surge of moisture and for storms to begin rotating.
All of the bi-state will experience well above average temperatures on Tuesday, with highs in the mid-upper 70s and dew points in the upper 50s and low 60s, which is a contributing element to our severe weather potential.
Storms are expected to develop out ahead of a cold front by Tuesday evening. Forecast models are not in complete agreement on when storms will initiate, but generally we think the first storms will develop sometime after 8-9PM in our northwestern counties and evolve from there.
Strong storms are expected to arrive in St. Louis somewhere between 10PM and midnight, and could be ongoing into the pre-dawn hours of Wednesday. Most thunderstorm activity should end by mid-morning Wednesday as the cold front exits to our southeast.
The primary threats will be large hail in excess of 1" diameter (quarter size), and damaging winds of 60+ mph. A few tornadoes cannot be ruled out, either. The most favorable area for tornadoes will be along and south of I-44, but the possibility is there for the entire viewing area.
The Storm Prediction Center has placed almost all of our viewing area in an enhanced (3/5) risk for severe weather tomorrow night.
Since thunderstorms will likely be rolling through during a time when most people are asleep, it's imperative that you have a way to receive warnings in the middle of the night. NOAA radios are ideal for this scenario, and you can find those at your local hardware store. You can also download the free KSDK weather app and set your exact location to receive up to the minute watch and warning information right to your phone. Make sure you have the volume turned on on your phone so you can hear the alert come through.
The 5 On Your Side weather team will be here around the clock to keep you updated. You can find the latest information at ksdk.com/weather, and by following our team on Facebook and Twitter.