We get tornado warnings/watches all the time now. It's become a regular occurrence around here.
The northeast has seen the largest increase in wintertime average temperatures over the last 40 years. I believe it's a 4.7F increase in average winter temperature.
We've had no measurable snowfall the last two winters which is crazy. Of course just when I get my ZR2 LOL.
Many daily records I see for my forecast area in Wakefield NWS clearly indicate it was both hotter and colder well back in time… In the winter of 1899 there was a 4 day stretch of record cold high temps on my region. Same was true in 1940. Then the hottest temps ever recorded go well back to the 1930s and 1910s… 107 the all time hottest high temperature recorded was from the 1930s. I will double check that…
The winters in the last 13 years I have noted varying weather conditions… December 2013 and 2014 both the warmest on record… By a solid margin… However the moths after those Decembers it was either really, really cold or a little below average. Plus both winters we had numerous good snow storms… February 2015 was the 4th coldest in record in Richmond… It was brutally cold that month. We had high temperatures in the last week of that month where it did not get much above 20 degrees Fahrenheit… That is remarkably cold for the last week of February.
We actually got to below 0 degrees Fahrenheit in January 2016 and 2017. Those two winters were marked with very cold weather and very warm weather too.
The December of 2010 turned out to be the coldest on record…. Beating the December of 1989.
The overall winter pattern for this region is set by the NAO pattern, PNA pattern and the AO pattern to a degree too. Plus the activity or lack of activity in the southern jet stream is a huge factor too. Another factor is the activity in the upper level of the atmosphere in the northern jet stream. Those systems start surface cyclogenesis in the Gulf of Mexico or off the southeast US coast. One last factor is the polar vortex… People in the media acted like this was a new “phenomenon” 5 or so years ago. It’s not…. I have read about that for the past 24 years on Weather Prediction Center forecast.
Many factors go into what happens in the observational weather we see and notice. A negative or turning negative North Atlantic Oscillation paired with a positive Pacific North American pattern is an early signal to a potential storm and trough in the eastern US. GFS forecasts for those patterns are fairly accurate to 7 days out. Beyond 10 days there are no where near as accurate. In the winter time I look at those and the GFS model runs to see what is possibly going to happen days 6-10.
As far as tornadoes go… I think the advent and usage of Doppler radar and the ability to see winds inside a thunderstorm has allowed for more possible warnings to be issued. The wind velocity radar can be extremely easy to spot a tornado if it’s relatively close to a radar site. I saw a EF-3 that hit Suffolk in my area in 2008 and it was extremely obvious it was a strong tornado. The dual pol radar is ok… I think it’s helpful to diagnose a strong tornado like a EF-2 or stronger tornado. It sees the debris thrown high up into the atmosphere. Which only stronger tornadoes really do that.
The strongest tornado to hit the northeast happened in Worcester Massachusetts.. And that was in the early 1950s from the top of my memory. And the strongest hurricane was the Long Island express hurricane of 1938. Which was a strong category 3 hurricane that was moving north at 60 mph… That was an amazingly fast pace for a hurricane to be moving.
What creates tornadoes is a strong upper level system with cold air aloft over spreading a buoyant warm surface layer that is destabilized by sunshine, wind shear with changes in direction and height, a developing low level jet too, a developing surface low pressure and a warm front as well.
Those conditions can happen any time of the year… In my area 30 years ago we had the largest tornado outbreak in recorded history. And it was in August… Not a typical time for that to happen. But it did…
Yesterday all of the parameters were met for a strong event to take place… This summer it has been surprisingly cool in my area for the most part. The month of June we had almost every day with below average high temperatures seen. That introduces an active upper level jet stream along with upper level vortices moving along that too. Which are typically the missing pieces to severe weather this time of year. So, to no surprise to me we had the possibility of having a bad weather event possibly happen.
In the stupid hot summer of 2010 we had no such events take place… And with the derecho of 2013 we had what is not totally uncommon in the summer weather pattern. A very strong line of thunderstorms moving east at 50-60 mph where the jet stream pushes the storms east at a high rate of speed on the northern periphery of a strong high pressure ridge to the south.