For those living from NC up through NYC and parts of New England, last night turned quite windy behind the cold front. The thought was that the highest wind gusts would most likely occur with the squall line (possibly > 50 kts), then more general gusts to 40-45 kts (45-50 mph) behind the front with a rapid pressure rise. Not a bad forecast, but it was the post-frontal wind that wreaked the most havoc with many locations seeing wind gusts from 50-65 mph causing power outages, downed trees, and even some shingles blown off of buildings!
So what happened?! Was it purely pressure gradient force (+ 7 mb per hour behind the front)? Strong low-level jet? Stratospheric intrusion? Maybe a little bit of each.
Although the above animation is grainy due to the ~8-10 km resolution of the sounder, I wanted to focus on the Mid-Atlantic and match up the red-coloring of the stratospheric intrusion with the wind speeds and gusts (12z 03/12/14 – 12z 03/13/14). The highest wind gusts occur as the stratospheric drying is moving into the Mid-Atlantic and are stronger than the winds seen through the mountains and points west (it was quite breezy though). I would speculate that the deep mixing in this dry layer prior to sunset was maintained as it crossed the Allegheny and Blue Ridge Mountains. Could the mountains have helped to maintain the deep vertical circulations that helped to transport the higher winds aloft to the surface? Most of the 60+ gusts occurred from 7-10 pm.
I’ve included some higher resolution MODIS images with the same obs to show off what GOES-R resolutions (2 km) would look like for this case.
Unfortunately, we didn’t get the best ozone retrievals produced by Dr. Emily Berndt (SPoRT) for this event, but I have included the 06 UTC 03/13/14 retrievals for a proof on concept. Notice the higher ozone moving towards the Mid-Atlantic, further supporting the stratospheric component to the red-coloring on the Air Mass product.
Overall, an impressive non-convective wind event that continued offshore (not shown). It may be possible to identify these events using the air mass before the first damaging winds occur. . .
Thanks for reading!