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Convective Thread

weatherwiz

By weatherwiz,
in New England

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dryslot

dryslot

Posted
Posted
Just now, tamarack said:

Radar there looks hailicious!  Some pixels of 55-60 dbz.   Best-looking cells divided to bypass my place; what else is new?

Going to miss the brunt of it to the north it seems, Had a strong cell last night as well with over .50" of rain.

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Ginx snewx

Ginx snewx

Posted
Posted

NWS has confirmed an EF-1 tornado touched down in Dutchess County, NY yesterday. 

  

OUS41 KALY 011823
PNSALY
NYZ064>066-020630-

PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE ALBANY NY
223 PM EDT Thu Jun 1 2017

...National Weather Service Confirms EF-1 Tornado in Dutchess 
County, New York...

LOCATION...Town of Wappinger, Dutchess County, New York

DATE...May 31, 2017

ESTIMATED TIME...714 PM

MAXIMUM EF SCALE RATING...EF-1

ESTIMATED MAXIMUM WIND SPEED...100

ESTIMATED PATH WIDTH...One Quarter Mile

PATH LENGTH...1.25 Miles

BEGINNING LAT/LON...41.64/-73.87

ENDING LAT/LON...41.64/-73.85

* FATALITIES...None
* INJURIES...None

* THE INFORMATION IN THIS STATEMENT IS PRELIMINARY AND SUBJECT TO
  CHANGE PENDING FINAL REVIEW OF THE EVENT AND PUBLICATION IN
  NWS STORM DATA.

...SUMMARY...

The National Weather Service in coordination with Dutchess County
Emergency Management officials, have confirmed a brief touchdown
of a tornado on May 31. The tornado path began near the
intersection of Maloney Road and Route 376. The tornado traveled due
east along and just north of Maloney Road for approximately 1.25 
miles before dissipating. Damage included numerous snapped 
hardwood and softwood trees and the roof lifted off a shed.
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OceanStWx

OceanStWx

Posted
Posted
On 5/31/2017 at 10:19 AM, Phillifan22 said:

A SE surface wind is both a backed wind, and also can be referred to as veering, IF the winds turn clockwise with height relative to that SE surface wind. It is backed compared to the rest of the wind field, and the entire wind field is veering. (Ex: SE at Surface, S at 925 mb, WSW at 800mb, SW or W at 500 and up).

 

On 5/31/2017 at 10:20 AM, Phillifan22 said:

Also: Veered or Veering is the winds turning clockwise with height. Backed or backing is the winds turning counterclockwise with height.

This about covers it. The key distinction is whether you are talking about with height or surface winds. 

Surface winds back if they turn counter-clockwise (i.e. S to SE), veer if they turn clockwise (S to SW). Like you say, backed winds at the surface can veer with heights if the wind aloft are westerly. 

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CT Rain

CT Rain

Posted
Posted
Just now, CT Rain said:

Actually <0.5 for some reason. It didn't really spike until it became much broader.

Maybe too small to resolve?

What is interesting is that spectrum width really spiked for those 2 SAILS scans with the tornado... was quite a bit lower before and after. 

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CT Rain

CT Rain

Posted
Posted
9 minutes ago, OceanStWx said:

Radar range shouldn't have been a problem (I think it's 10,000 feet).

Yeah it's sampling at 6kft there so I'm not sure why NROT was so lame. The "away" side of the mesocyclone only comprised like 3 radials so even though the couplet was tight the algorithm may not have resolved it well. 

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CT Rain

CT Rain

Posted
Posted
4 minutes ago, weatherwiz said:

Good stuff Ryan and EXCELLENT call the day before...I mean I don't think you can ever beat a call like that 

Thank Wiz. I remember thinking Dutchess Co for a chase spot for you but didn't remember if I tweeted it or not lol

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OceanStWx

OceanStWx

Posted
Posted
Just now, CT Rain said:

Yeah it's sampling at 6kft there so I'm not sure why NROT was so lame. The "away" side of the mesocyclone only comprised like 3 radials so even though the couplet was tight the algorithm may not have resolved it well. 

True. I think some of the calculation is done with 3 bins, so maybe it was a sample size issue.

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CT Rain

CT Rain

Posted
Posted
Just now, OceanStWx said:

True. I think some of the calculation is done with 3 bins, so maybe it was a sample size issue.

Yeah closer to the radar where the bins aren't as large you probably would have had a much better nrot signature. Good reminder that not all algorithms are perfect - especially at longer ranges.

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OceanStWx

OceanStWx

Posted
Posted
1 minute ago, CT Rain said: 

<blockquote class="twitter-tweet" data-lang="en"><p lang="en" dir="ltr">Just go to Dutchess Co NY</p>&mdash; Ryan Hanrahan (@ryanhanrahan) <a href="https://twitter.com/ryanhanrahan/status/869608029284597760">May 30, 2017</a></blockquote>
<script async src="//platform.twitter.com/widgets.js" charset="utf-8"></script>

 

Well there you go. You gotta get in on this NWS forecast challenge.

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OceanStWx

OceanStWx

Posted
Posted

http://rammb.cira.colostate.edu/templates/loop_directory.asp?data_folder=dev/lindsey/loops/31may17_band2&image_width=640&image_height=480&loop_speed_ms=50

I think you all can see this loop, but you can see the tornado probably resulted from the merger of two updrafts towards the end of the loop. Two separate storms form around 22z, and just before 23z they merge. The result is a nice overshooting top just about tornado touchdown time. According to Ryan, not ALY. ;)

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CT Rain

CT Rain

Posted
Posted
5 minutes ago, OceanStWx said:

http://rammb.cira.colostate.edu/templates/loop_directory.asp?data_folder=dev/lindsey/loops/31may17_band2&image_width=640&image_height=480&loop_speed_ms=50

I think you all can see this loop, but you can see the tornado probably resulted from the merger of two updrafts towards the end of the loop. Two separate storms form around 22z, and just before 23z they merge. The result is a nice overshooting top just about tornado touchdown time. According to Ryan, not ALY. ;)

Nice catch - yeah I think that's definitely the case. We were watching that storm out in front that moved from Ulster Co and weren't sure how it was going to interact with the main line. I figured it would fizzle but the merger actually allowed the thing really to surge in strength.

The 22z HRRR has some atrocious low level SRH at POU with really weak 0-3km wind fields but it's a good reminder that with favorable conditions for supercells in general (good deep layer shear) cell mergers and interactions can do some funky stuff in low levels and locally enhance SRH etc. 

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weatherwiz

weatherwiz

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  • Author
Posted
53 minutes ago, CT Rain said:

Thank Wiz. I remember thinking Dutchess Co for a chase spot for you but didn't remember if I tweeted it or not lol

Yeah you did.  I was seriously thinking about it.  They always get nailed.  B/c my friend from NH was in a car accident (he and his car are fine but he doesn't want to drive a long distance until insurance goes through and it's fixed) he wasn't coming down here this year so I was going to be picking him up if we chased.  

If the day before I didn't have to go to Naugatuck, Danbury, Shelton, and Milford I was going to pick him up that night.  I didn't get back to WeHa tough until after 11 and it would have been arouhd 12:45 when I got him then probably 3 AM when we got back.  

But we had a successful trip...some pea/dime hail and what really looked like a rotating wall cloud.  

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OceanStWx

OceanStWx

Posted
Posted
Just now, CT Rain said:

Nice catch - yeah I think that's definitely the case. We were watching that storm out in front that moved from Ulster Co and weren't sure how it was going to interact with the main line. I figured it would fizzle but the merger actually allowed the thing really to surge in strength.

The 22z HRRR has some atrocious low level SRH at POU with really weak 0-3km wind fields but it's a good reminder that with favorable conditions for supercells in general (good deep layer shear) cell mergers and interactions can do some funky stuff in low levels and locally enhance SRH etc. 

I hate cell mergers. Mainly because they basically go one of two ways: either increase updraft strength or decrease updraft strength. They rarely ever maintain updraft strength. And it's next to impossible to guess which outcome will occur.

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weatherwiz

weatherwiz

Posted
  • Author
Posted
2 minutes ago, CT Rain said:

Nice catch - yeah I think that's definitely the case. We were watching that storm out in front that moved from Ulster Co and weren't sure how it was going to interact with the main line. I figured it would fizzle but the merger actually allowed the thing really to surge in strength.

The 22z HRRR has some atrocious low level SRH at POU with really weak 0-3km wind fields but it's a good reminder that with favorable conditions for supercells in general (good deep layer shear) cell mergers and interactions can do some funky stuff in low levels and locally enhance SRH etc. 

Another 10-15 knots of low-level shear and yesterday would have been very interesting.  Sfc winds stayed mainly SE across much of the region too which is usually a strong signal for something...especially when you break into some sun and erode CIN

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CT Rain

CT Rain

Posted
Posted
8 minutes ago, weatherwiz said:

Another 10-15 knots of low-level shear and yesterday would have been very interesting.  Sfc winds stayed mainly SE across much of the region too which is usually a strong signal for something...especially when you break into some sun and erode CIN

Yeah there was some turning but the wind fields at 850mb and even 700mb were very meh. 

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OceanStWx

OceanStWx

Posted
Posted
10 minutes ago, CT Rain said:

Check this out - the cell merger by looking at ZDR in the bottom left about 13kft ARL. As soon as that cell merger happens the updraft definitely strengthens with a lot of liquid water getting lofted. It's a really quick spike. 

Good grab there. 

It's almost like sometimes updrafts can constructively merge, where the more northward moving cell just ahead of the more southeastward moving cell can enhance the counter-clockwise rotation of the SE mover.

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