Isolated thunderstorms will be possible Sunday afternoon through early evening ahead of a cold front. Recently, some data has been hinting toward a potentially severe event. Unlike past events, this is an extremely complex forecast with many driving factors. While potentially widespread, conditions leading up to the event may very well also hinder development. The main question will be whether storms materialize or not.
Timing: The main severe threat appears to be anytime after 12:00 noon through sunset.
Main Threats: All modes of severe weather are possible, including damaging winds, large hail, heavy rainfall, and an isolated tornado.
Midday tomorrow will feature an advancing warm front, which will cause clouds and scattered showers throughout the region. Behind the warm front will be an extremely moist air mass (dew points in the mid-upper 70’s). This will help result in high CAPE (Convective Available Potential Energy) values of up to ~3,000 J/kg, which is extremely favorable for severe weather development. Also, there will be a good deal of shear, which could allow for a few cells to rotate, resulting in an isolated tornado or two. While likely not a widespread tornadic event, it cannot be completely ruled out at any given location. The Storm Prediction Center has placed nearly our entire region in a slight risk (level 2 out of 5) for severe thunderstorms.
Simulated radar for Sunday (Aug 2nd) :
Conflictingly, many model runs show lingering cloud cover after the warm front passes, which will put a cap on any convection. Also, widespread cloud cover will not allow for surface heating, which is essential for updrafts. This appears to be the case on the most recent run of the Nam 3 km, which doesn’t show much convective development due to cloud cover. While a possible solution, it will only take a couple of breaks of sunshine to create a very unstable atmosphere, resulting in severe thunderstorm development. Like always, we will monitor this situation and give updates as we get closer in time.
Have a great evening!