Late in the afternoon, as convection continued along the southern fringe of BTV’s county warning area, a storm cell began pulsing up and down.  This series of images shows how the max reflectivity on radar and the maximum updraft output from 3D-VAR began oscillating.  Maximum updraft strength from 3D-VAR would precede a peak in radar reflectivity by about 20 minutes.  We issued a warning for a southern BTV county, based on the Max Updraft data.  The storm produced 3/4 inch hail.

2205z.  Reflectivity is maximizing from a previous pulse, and current Max updraft values are less than 10 m/s.

2235z. Maximum Updraft values around 14 m/s. Max Reflectivity around 56 dbz.

2300z. Max Reflectivity back up to 60 dbz, while Max Updraft Strength continues around 18 m/s.

Dankers/Kearney