The Annual Countdown to May 1st Thread ©

[weatherwiz]

7 days!!! One week!!!

[Damage In Tolland]

First 7 days look benign with slightly AN temps , but no big heat or storms 

[weatherwiz]

Still have this showing up for May 1st  

[weatherwiz]

6-days to go!!!

[weatherwiz]

5 days!!!!!

[weatherwiz]

4 days people!!!!

[weatherwiz]

TWO DAYS...TWO Days...TWO DAYSSSSS!!!!!!

[dendrite]

Awesome. Then we can start the countdown to warm weather.

[CT Rain]

22 minutes ago, weatherwiz said:

TWO DAYS...TWO Days...TWO DAYSSSSS!!!!!!

You're more excited about 5/1 than the severe weather we had on Friday lol

[weatherwiz]

Just now, CT Rain said:

You're more excited about 5/1 than the severe weather we had on Friday lol

I think I'm still in shock lol. The past few years have been rather crazy. Not sure if marginal is the proper term to use (don't think so), but the set ups we have had which have produced severe wx just don't seem like set sups which typically work out here. Take last September/early October for example, can you think of any other years which had similar set ups and yielded similar results? I totally understand the fact that similar setups don't always yield similar results, but we've had to have numerous set ups like those in the past...so what is the driving factor between producing/not? 

The same with this past Friday...I know we have had set ups like Friday but can you remember seeing hail like that in a set up like this here? It just seems like these things are all of a sudden producing. 

[CT Rain]

Just now, weatherwiz said:

I think I'm still in shock lol. The past few years have been rather crazy. Not sure if marginal is the proper term to use (don't think so), but the set ups we have had which have produced severe wx just don't seem like set sups which typically work out here. Take last September/early October for example, can you think of any other years which had similar set ups and yielded similar results? I totally understand the fact that similar setups don't always yield similar results, but we've had to have numerous set ups like those in the past...so what is the driving factor between producing/not? 

The same with this past Friday...I know we have had set ups like Friday but can you remember seeing hail like that in a set up like this here? It just seems like these things are all of a sudden producing. 

It definitely was odd but the environment supported it with that storm firing up on the leading edge of a nice MUCAPE plume and also plenty of effective shear. A lot of times we can get 1-2k joules of MU CAPE above the stable boundary layer but there's not much effective vertical shear even though 0-6km shear is off the charts. 

[weatherwiz]

1 minute ago, CT Rain said:

It definitely was odd but the environment supported it with that storm firing up on the leading edge of a nice MUCAPE plume and also plenty of effective shear. A lot of times we can get 1-2k joules of MU CAPE above the stable boundary layer but there's not much effective vertical shear even though 0-6km shear is off the charts. 

Gotcha...that makes much more sense. After last fall and now this past Friday I know I'm definitely going to be looking much more closely at 0-3km/0-6km CAPE and effective vertical shear/helicity. I know we had the super low freezing levels, but you still need to have a pretty significant updraft to still at least produce hail of that magnitude. 

I also think synotpically things ended up being much more favorable that what was originally modeled. I think the s/w not only dug much more but ended up being much stronger and as a result so overall lift alone was strengthened and that probably enhanced the likelihood of parcels lifting to the LFC and once they hit the unstable layer they just took off. Going back and looking at mesoanalysis it looked like the timing of the MUCAPE plume/effective shear was nearly perfect. 

[CT Rain]

1 minute ago, weatherwiz said:

Gotcha...that makes much more sense. After last fall and now this past Friday I know I'm definitely going to be looking much more closely at 0-3km/0-6km CAPE and effective vertical shear/helicity. I know we had the super low freezing levels, but you still need to have a pretty significant updraft to still at least produce hail of that magnitude. 

I also think synotpically things ended up being much more favorable that what was originally modeled. I think the s/w not only dug much more but ended up being much stronger and as a result so overall lift alone was strengthened and that probably enhanced the likelihood of parcels lifting to the LFC and once they hit the unstable layer they just took off. Going back and looking at mesoanalysis it looked like the timing of the MUCAPE plume/effective shear was nearly perfect. 

And more specifically you need a robust mesocyclone. The vertical pressure deficit from the meso increases updraft strength and will give you the big hail. CAPE is a part of this but the meso is key. 

I actually thought it was well modeled. The HREF and HRRR had some nice cells with good mid level mesocyclones on the leading edge of that instability plume. 

[weatherwiz]

2 minutes ago, CT Rain said:

And more specifically you need a robust mesocyclone. The vertical pressure deficit from the meso increases updraft strength and will give you the big hail. CAPE is a part of this but the meso is key. 

I actually thought it was well modeled. The HREF and HRRR had some nice cells with good mid level mesocyclones on the leading edge of that instability plume. 

What tools or I guess ways to analyze or I guess visualize something like vertical pressure changes? I know this is a huge (and perhaps maybe even underrated or underanalyzed) aspect of convection and I've at least never done much with assessing this, outside of using the UD helicity products which is a pretty fantastic tool...although I'm starting to feel like some (mainly in the twitter world) misuse the product and directly correlate to tornadic activity...which I'm thinking isn't an entirely correct correlation (though obviously there can be a connection). 

The HRRR definitely did highlight this well...I'm disappointed I really didn't look more into it Thursday night and through Friday morning. It picked up quite well with the initial cells which developed. 

[OceanStWx]

1 hour ago, CT Rain said:

It definitely was odd but the environment supported it with that storm firing up on the leading edge of a nice MUCAPE plume and also plenty of effective shear. A lot of times we can get 1-2k joules of MU CAPE above the stable boundary layer but there's not much effective vertical shear even though 0-6km shear is off the charts. 

The effective shear is such a nice tool that SPC added to their meso plots. And now you can see it modeled to some effect on SHARpy soundings on the model sites. 

An example being IAD from Friday. You have great mid level lapse rates (nice 150mb layer of 7.5C/km), and over 40 kt 0-6km shear. Normally we bang that.

But see the purple bracket showing the effective inflow layer. It's elevated, meaning the near surface parcels are not buoyant enough to be part of the inflow (i.e. tornado environment is not great). 

Of course it's complicated as all get out to manually do, because you're looking for each parcel that meets GTE 100 J/kg CAPE and GTE -250 J/kg CIN as enough buoyancy for the inflow layer. Then you take shear up to 50% of the EL to get your effective shear. 

[OceanStWx]

1 hour ago, weatherwiz said:

What tools or I guess ways to analyze or I guess visualize something like vertical pressure changes? I know this is a huge (and perhaps maybe even underrated or underanalyzed) aspect of convection and I've at least never done much with assessing this, outside of using the UD helicity products which is a pretty fantastic tool...although I'm starting to feel like some (mainly in the twitter world) misuse the product and directly correlate to tornadic activity...which I'm thinking isn't an entirely correct correlation (though obviously there can be a connection). 

The HRRR definitely did highlight this well...I'm disappointed I really didn't look more into it Thursday night and through Friday morning. It picked up quite well with the initial cells which developed. 

Oh there can be a correlation between UH swaths and tornado activity, but that's because supercells overwhelming produce the majority of tornadoes. Some models, like the HRRR, can discriminate between 2-5km UH (mid level) and 0-2 (low level). Having higher amounts of 0-2km UH will correlate even higher with tornado reports in most cases. But the most important thing is knowing the environment. 

You are asking yourself can supercells form, and what type of inflow access do those supercells have. 

[CT Rain]

3 minutes ago, OceanStWx said:

The effective shear is such a nice tool that SPC added to their meso plots. And now you can see it modeled to some effect on SHARpy soundings on the model sites. 

An example being IAD from Friday. You have great mid level lapse rates (nice 150mb layer of 7.5C/km), and over 40 kt 0-6km shear. Normally we bang that.

But see the purple bracket showing the effective inflow layer. It's elevated, meaning the near surface parcels are not buoyant enough to be part of the inflow (i.e. tornado environment is not great). 

Of course it's complicated as all get out to manually do, because you're looking for each parcel that meets GTE 100 J/kg CAPE and GTE -250 J/kg CIN as enough buoyancy for the inflow layer. Then you take shear up to 50% of the EL to get your effective shear. 

I've noticed that a lot of the time we get these elevated instability plumes on the nose of a good LLJ. So you wind up with pretty crappy effective shear given the fact the winds are ripping in the effective inflow layer and winds don't increase much above that so you're left with a lot of 0-6km shear but minimal effective shear.

It's definitely a great tool that is pretty valuable in these cases (and many of the sunrise bangers we get). 

[OceanStWx]

6 minutes ago, CT Rain said:

I've noticed that a lot of the time we get these elevated instability plumes on the nose of a good LLJ. So you wind up with pretty crappy effective shear given the fact the winds are ripping in the effective inflow layer and winds don't increase much above that so you're left with a lot of 0-6km shear but minimal effective shear.

It's definitely a great tool that is pretty valuable in these cases (and many of the sunrise bangers we get). 

I mean the 8/4/15 sunrise surprise shows a much more scary set up on the 12z CHH sounding.

Effective inflow was to the surface despite over -150 J/kg CIN (remember criteria is GTE -250). Effective shear 56kt. Theta-e difference of 26 in the lowest 400 mb. Screams wind potential.

[Torch Tiger]

3 hours ago, weatherwiz said:

TWO DAYS...TWO Days...TWO DAYSSSSS!!!!!!

Big May incoming. 

[CT Rain]

[weatherwiz]

1 hour ago, OceanStWx said:

The effective shear is such a nice tool that SPC added to their meso plots. And now you can see it modeled to some effect on SHARpy soundings on the model sites. 

An example being IAD from Friday. You have great mid level lapse rates (nice 150mb layer of 7.5C/km), and over 40 kt 0-6km shear. Normally we bang that.

But see the purple bracket showing the effective inflow layer. It's elevated, meaning the near surface parcels are not buoyant enough to be part of the inflow (i.e. tornado environment is not great). 

Of course it's complicated as all get out to manually do, because you're looking for each parcel that meets GTE 100 J/kg CAPE and GTE -250 J/kg CIN as enough buoyancy for the inflow layer. Then you take shear up to 50% of the EL to get your effective shear. 

This is great information!!

1 hour ago, OceanStWx said:

Oh there can be a correlation between UH swaths and tornado activity, but that's because supercells overwhelming produce the majority of tornadoes. Some models, like the HRRR, can discriminate between 2-5km UH (mid level) and 0-2 (low level). Having higher amounts of 0-2km UH will correlate even higher with tornado reports in most cases. But the most important thing is knowing the environment. 

You are asking yourself can supercells form, and what type of inflow access do those supercells have. 

That is sort of what I was alluding to with my statement. If you have great 2-5km UH but weaker 0-2km....you could probably wager you're looking at a better chance for hail producing supercells against tornadic supercells, but if you have strong 0-2km tornadic supercells can probably be hit harder. 

[weatherwiz]

oh man...I forgot to do a thread for western PA for Wednesday. If the steeper lapse rates can get into that area there could be a few boundary riding supercells

[weatherwiz]

1 day to go!!!

Notice how I had to take the "s" away from days...incredibly exciting stuff. 

[Cyclone-68]

We’re long overdue for a derecho. Maybe this summer will deliver 

[weatherwiz]

MAY 1st!!!!!!!

Happy May 1st!!!!!!

[Torch Tiger]

15 hours ago, Cyclone-68 said:

We’re long overdue for a derecho. Maybe this summer will deliver 

Two or three

[SlantStickers Anonymous]

Happy belated May 1, Wiz. 

[Torch Tiger]

the south coast of RI and MA, where a lone thunderstorm was
already marching east. Not expecting severe weather from this
thunderstorm, as there is simply not enough energy to work with.
This storm was barely capable of producing lightning.

 

Trolling? ;D

[ineedsnow]

Paul check out this one two confirmed tornados Otg 

TXC033-115-060130-
/O.CON.KMAF.TO.W.0018.000000T0000Z-190506T0130Z/
Borden TX-Dawson TX-
758 PM CDT Sun May 5 2019

...A TORNADO WARNING REMAINS IN EFFECT UNTIL 830 PM CDT FOR
NORTHWESTERN BORDEN AND NORTHEASTERN DAWSON COUNTIES...

At 758 PM CDT, a confirmed tornado was located 7 miles east of
O`donnell, or 15 miles south of Tahoka, and is nearly stationary.

HAZARD...Damaging tornado and golf ball size hail.

SOURCE...Weather spotters confirmed two tornadoes about 15 miles
         northwest of Gail

[weatherwiz]

10 hours ago, ineedsnow said:

Paul check out this one two confirmed tornados Otg 

TXC033-115-060130-
/O.CON.KMAF.TO.W.0018.000000T0000Z-190506T0130Z/
Borden TX-Dawson TX-
758 PM CDT Sun May 5 2019

...A TORNADO WARNING REMAINS IN EFFECT UNTIL 830 PM CDT FOR
NORTHWESTERN BORDEN AND NORTHEASTERN DAWSON COUNTIES...

At 758 PM CDT, a confirmed tornado was located 7 miles east of
O`donnell, or 15 miles south of Tahoka, and is nearly stationary.

HAZARD...Damaging tornado and golf ball size hail.

SOURCE...Weather spotters confirmed two tornadoes about 15 miles
         northwest of Gail

Nuts!