General Severe Weather Discussion 2018

[weatherwiz]

6 minutes ago, OceanStWx said:

The timing and location of forcing is certainly important. I think also having the warm front draped across the region was helpful too, whereas the busted event before that it blew through to Canada.

Warm front positioning and storm motion were very key here. The storm motion was virtually right along the warm front and we had one of the more impressive differential heating boundaries you’ll see

[OceanStWx]

22 hours ago, vortex95 said:

There has been a distinct downward trend of U.S. tornado activity starting in 2012.  Some stats:

Going by inflation adjusted tornado counts, through 10/3/18, it is the lowest count on record (since 1950).

https://4k4oijnpiu3l4c3h-zippykid.netdna-ssl.com/wp-content/uploads/2018/10/SPC_torgraph.png

 

5 tornado fatalities so far this year.  This is the lowest on record for so late in the year.

 

No EF4 tornadoes in the U.S in 525 days.  This is the longest period on record by 40 days and counting.

 

10 EF3 tornadoes so far this year which is at record low levels for the second year in a row.  2017 had

15 which was the lowest in 30 years.

 

Through 10/6, it has been 1964 days since the last EF5 tornado.  This is the second longest period on

record.  The record is 2922 days set 1999 to 2007.

 

From 5/16/17 to 3/19/18 (306 days), no EF3 tornado occurred in the U.S.  This is by far the longest

EF3+ gap since reliable records began in early 1950s.

From 5/17/17 to 2/23/18 (283 days), there were no tornado fatalities in the  U.S.  This is the longest

stretch on record.

In 2018, only 3 EF3+ tornadoes occurred through 5/31.  This is the least amount so late into a year in

modern records.

 

Longer term, the tornado drought since 2012 continues with 2018 possibly under 1000 tornado total,

which would make it the 5th time in 7 years.  From 1990 to 2011, every year except 2002 was above

1000.  Record low monthly tornado counts for February, March, May, July, and August have all

occurred since 2010 going back to 1985.

 

That is consistent with the expected trends due to climate change (), which of course comes with a load of caveats. The tornado record only goes back to 1950, is fairly subjective in nature, and prone to many errors. But the effects of climate change would be to increase CAPE (more moisture) but also decrease shear (as temp differences across the globe are smoothed out). Overall that would suggest a decrease or weakening of tornadoes.

Locally? Maybe not, as CAPE is usually our limiting factor.  But our tornado record is probably even worse than the rest of the country and prone to small sample size errors. 

[weatherwiz]

2 minutes ago, OceanStWx said:

That is consistent with the expected trends due to climate change (), which of course comes with a load of caveats. The tornado record only goes back to 1950, is fairly subjective in nature, and prone to many errors. But the effects of climate change would be to increase CAPE (more moisture) but also decrease shear (as temp differences across the globe are smoothed out). Overall that would suggest a decrease or weakening of tornadoes.

Locally? Maybe not, as CAPE is usually our limiting factor.  But our tornado record is probably even worse than the rest of the country and prone to small sample size errors. 

I wonder if we could also start seeing a shift in peak maximum...I know now there are two maximums (spring and a weaker one in the fall) but theoretically we should still yield large enough temperature gradients in the NH winter to yield strong shear, however, increasing moisture/CAPE. Perhaps eventually we’ll see bigger numbers geared more towards late fall and into early spring? 

[OceanStWx]

4 minutes ago, weatherwiz said:

Warm front positioning and storm motion were very key here. The storm motion was virtually right along the warm front and we had one of the more impressive differential heating boundaries you’ll see

12z PIT had right movers at 284/28, and by 00z OKX was 282/31. So for an entire 12 hour stretch it was pretty favorable for any east/west oriented boundary.

[weatherwiz]

Just now, OceanStWx said:

12z PIT had right movers at 284/28, and by 00z OKX was 282/31. So for an entire 12 hour stretch it was pretty favorable for any east/west oriented boundary.

Something you don’t see here very often. I remember a setup in the mid-to-late 90’s which was similar. I want to say maybe like 96 or 97. All I remember it being though was during the summer and on a Friday. We had a TOR go up I think around 11:30 AM

[OceanStWx]

Just now, weatherwiz said:

I wonder if we could also start seeing a shift in peak maximum...I know now there are two maximums (spring and a weaker one in the fall) but theoretically we should still yield large enough temperature gradients in the NH winter to yield strong shear, however, increasing moisture/CAPE. Perhaps eventually we’ll see bigger numbers geared more towards late fall and into early spring? 

Plausible, as long as you aren't in a pattern that is scouring out Gulf moisture. 

[weatherwiz]

18 minutes ago, OceanStWx said:

Plausible, as long as you aren't in a pattern that is scouring out Gulf moisture. 

True

[CT Rain]

3 hours ago, OceanStWx said:

There is a lot of evidence that points to thresholds being necessary for severe weather. But it is a sliding scale, because you are trying to balance shear with instability. Too much shear and too little instability isn't good, but neither is too much instability and too little shear. 

Then you also have issues like our tornado parameter space looks an awful lot like our flash flood parameter space. How do we establish which threat will dominate?

Sort of reminds me of that big tornado even last summer in Indiana. Big miss by SPC. Neither instability nor shear were off the charts but they were perfectly co-located for several hours and everything wound up going to town. 

[Ginx snewx]

On 10/3/2018 at 10:12 PM, CT Rain said:

Second tornado touchdown in Mansfield, CT? Looks like Kevin just missed a tree topper. 

Woah I missed this, was under anesthesia at the time. Any damage, never mind just caught up 

confirmed that a weak EF0 tornado touched down in the town of
Mansfield, Connecticut on Tuesday, October 2nd. We were able to
confirm this tornado based on a number of sources, including an
eyewitness account, information from the Mansfield Emergency
Management director, aerial drone footage provided by the media,
and a weak tornado debris signature seen on Doppler radar.

Trees were downed, in a very chaotic pattern, starting from just
west of Storrs Road (Route 195) between Cemetery Road and Bassetts
Bridge Road and continuing east-northeastward across Cemetery
Road and ending just to the east of the southernmost portion of
Echo Road. Several shingles were blown off of a roof on Storrs
Road and were found 500 yards downstream. A person living on
Centre Street, just west of Echo Lake observed a swirling mass of
leaves and sticks passing to his southeast, some of which were
hitting his house. The Mansfield Emergency Management Director
walked the path and found that downed trees north of Cemetery Road
were facing the southwest while they were mainly facing northeast
just to the south of Cemetery Road.

NWS-Norton would like to thank the Mansfield Office of Emergency
Management, NBC Connecticut, the eyewitness, and Skywarn amateur
radio operators for providing very useful information.