Mesoscale Vortex Ignites Supercell Tornado Risk in Western Maine, Northern New Hampshire — SevereWX

A mesoscale convective vortex crossing from Canada is setting the stage for intense thunderstorms in parts of western Maine, northern New Hampshire, and Vermont this afternoon.

Storms near the vortex have been fading, but new development is firing along a trailing outflow boundary from southwestern Quebec. This activity is tapping into a moist boundary layer with dewpoints near 70°F and CAPE exceeding 2000 J/kg—prime fuel for severe weather.

A warm elevated mixed layer (EML) cap is slowly eroding southward, allowing storms to root deeper into the unstable air. Strong wind shear will help some storms organize into supercells, posing risks for large hail (1.5-2.5 inches), damaging wind gusts (65-80 mph), and even a tornado or two (120-145 mph winds).

Expect scattered supercells to intensify between 4-6 PM EDT (20-22Z), spreading southeast toward Downeast Maine. A watch issuance looks likely within the hour, per SPC's 60% probability.

Peak Threats:

• Tornadoes: EF2 intensity most probable
• Hail: Up to tennis ball size
• Winds: 80 mph gusts

This setup echoes recent Slight Risk areas but highlights the vortex's role in sharpening the severe potential. Monitor radar closely as storms evolve.

Preparedness: Review your severe weather plan, ensure mobile alerts are on, and seek shelter if rotation or large hail is spotted. Stay safe!