Jump to content
  • Member Statistics

    17,586
    Total Members
    7,904
    Most Online
    LopezElliana
    Newest Member
    LopezElliana
    Joined

Spring/ Summer 2014 Convection Discussion


weatherwiz

Recommended Posts

While this Tuesday's (circa) convection ship hasn't completely set sailed, the dock hands are certainly removing the mooring cables... 

 

This has no where near the same look as it did 4 days ago, when the most guilty Euro was doing what it always does ...erroneously drilling lowering heights through the OV/NE regions.  Then, it had a stripe of hybridized continental/EML air in place, well timed diabatic heating, and strong vorticity advection entering the area, ...along with veered lower 200mb wind field.  It was tornado Tuesday on those runs back when. Even driving SPC to through up a D5/6 outlooks for the NE corridor.  

 

Now that the Euro bias has completed yet another demonstration of being a POS in that time range, the interest shifts toward the higher SBCAPE ... which is in the MA.  

 

Doesn't mean there won't be anything in the area..  We should pool theta-e in our own rite, and together with oreographic forcing and/or frontalysis convergent vectors, there's likely to be pulse strong storms, and invariable when those occur there are an isolated incident of severe or two or three.   Just probably less organized at this point.  Guess you call that a See TXT.  

 

I honestly don't think the setup 5 days ago for Tuesday as modeled looks much difference from how it looks now. I never really saw an EML kind of setup. 

Link to comment
Share on other sites

  • Replies 2.7k
  • Created
  • Last Reply

The point is that while this threat has some low-end potential, unless there's a major shift in the model guidance with a number of factors, this will probably be a See Text event, as Tip mentioned. I wouldn't even rule out a brief rain-wrapped spinner, for the record. When asked for ULL cases that support a "notable" severe event, all that's given is a cherry pick of 7/24/08 and no consideration is given to the numerous top analogs/setups that produced little to no severe weather across SNE.

 

lol - Quincy... go look at the research. There's been plenty of research about warm season cut-off lows and severe weather in the northeast. I don't know why you keep talking about "high end" severe not happening... no one ever thought it was. 

 

With the exception of the weird timing issues that popped up between the GFS and Euro the models have always shown a pretty strong signal for severe and even tornadoes Monday and Tuesday. Nothing has really changed IMO. 

Link to comment
Share on other sites

I honestly don't think the setup 5 days ago for Tuesday as modeled looks much difference from how it looks now. I never really saw an EML kind of setup.

I'll admit when the 00z Euro a few days ago was showing a roaring 50+ LLJ with strongly backed surface winds, I was a bit intrigued. Times have changed.
Link to comment
Share on other sites

The main thing that I've noticed is that with the ULL slowing down and then lifting out the main threat has shifted to west of the Hudson where the models have been focusing the heaviest precip for many runs now. This doesn't bode well for New England but increases the threat for NYC and points south and west. I still think that most areas see at least one good storm tomorrow and Tuesday but I don't see a setup which would allow for enough discrete development for severe. The atmosphere won't be capped and moisture will be plentiful. With the storm motion parallel to the front the main threat should be flash flooding, with perhaps some isolated hail and gusty winds. Activity looks to be too numerous for much more than that. At least away from the Mid-Atlantic.

Link to comment
Share on other sites

You don't need discrete for severe or even tornadoes necessarily.  You could have a multi-cell broken line where you have to watch the breaks for rotation.  

 

Having as much as 35-45 knots also at 850 with as much as 1000-1500 Cape is pretty significant.  If this were a setup with only 20-25 knots at 850 you would go meh but those shear values are quite significant.  

 

You also have shear values of around 25-30 m/s and those values are quite significant as well

Link to comment
Share on other sites

You don't need discrete for severe or even tornadoes necessarily. You could have a multi-cell broken line where you have to watch the breaks for rotation.

Having as much as 35-45 knots also at 850 with as much as 1000-1500 Cape is pretty significant. If this were a setup with only 20-25 knots at 850 you would go meh but those shear values are quite significant.

You also have shear values of around 25-30 m/s and those values are quite significant as well

I see large scall convective complexes looking at the high res data. Total washout type stuff, at least down this way.
Link to comment
Share on other sites

I honestly don't think the setup 5 days ago for Tuesday as modeled looks much difference from how it looks now. I never really saw an EML kind of setup. 

 

Then the trough axis was cutting through with strong DPVA, with lead theta-e and yes ...some hybridized continental/EML (Just not pure EML.   There was some mixing synoptically...)  

 

But that's less the point for me.  The main big deal is the weakening frontal mechanics and the correction toward the trough axis now not cutting through as depicted. In fact, it may never... It may fill and wind up a shear axis (this latter suggestion started to emerge 2 days ago).  The Euro is no longer plowing that feature through and that's a big loss in mechanical forcing there.

 

But anyway... I didn't realize I was getting in between you guys.  It's just my take on things.  Prolly be totally wrong.  word

Link to comment
Share on other sites

So the 45 knot LLJ on the Euro for Tuesday is a big change? lol

I'll post a comparison if you'd like in the banter thread, it's not a black and white matter of 45kt vs. 50kt. Anyway, why do you think the SPC went from 30% probs to 5% probs and lackluster wording if this is still an "impressive" setup as you said earlier today? I fully realize that SNE has had big days in See Text and SLGT risks, but even SPC is much less impressed.

I also recall a post saying the surface reflection didn't make sense given the ULL prog, yet now we're seeing a less amplified trough (slightly further north), still somewhat faster timing of the FROPA and other key forcing features (jetmax, vortmax, SLP) displaced NW of SNE.

Link to comment
Share on other sites

You don't need discrete for severe or even tornadoes necessarily.  You could have a multi-cell broken line where you have to watch the breaks for rotation.  

 

Having as much as 35-45 knots also at 850 with as much as 1000-1500 Cape is pretty significant.  If this were a setup with only 20-25 knots at 850 you would go meh but those shear values are quite significant.  

 

You also have shear values of around 25-30 m/s and those values are quite significant as well

Of course not...no.   TORs occur all over the world and for a variety reasons...  I've heard of colliding outflow boundaries curling around one another at the nexus point under an updraft causing EF2 land spout damage.   I mean geez.  

 

I think the interesting TORs are those that happen near the spout areas of Miami  and thereabouts.  They have such huge DPs there with clear air below the cloud bases, such that the wind whipped harbor spouts are really super hi def.  Kinda cool to geek out with video.

 

Anyway, I've noticed over the years that there appears to be higher frequency of discrete ...longer tracked type SC from open synoptic waves, and that weaker pulse TORs swarm in conjunction with closed deep layered circulations.  Those arcs of higher DBzs that rotate N from the western MV to the Dekotas in spring can have lots and lots of machine-triggered warnings, a few sites and sparadic damage. 

 

Contrasting, CAP punchers with 500mb temps falling over top as an open wave jet streak noses in (nice to have the typical SSE broad flow below the 850mb).  Nice.    

 

'Course, the difference between the two gets harder to define at times.

Link to comment
Share on other sites

I'll post a comparison if you'd like in the banter thread, it's not a black and white matter of 45kt vs. 50kt. Anyway, why do you think the SPC went from 30% probs to 5% probs and lackluster wording if this is still an "impressive" setup as you said earlier today? I fully realize that SNE has had big days in See Text and SLGT risks, but even SPC is much less impressed.

I also recall a post saying the surface reflection didn't make sense given the ULL prog, yet now we're seeing a less amplified trough (slightly further north), still somewhat faster timing of the FROPA and other key forcing features (jetmax, vortmax, SLP) displaced NW of SNE.

Exactly... Fropa slowed down. We thought the gfs timing was bogus.

As for the SPC I really don't judge how a threat changes based on what another forecaster who I don't know decides to do.

I feel like there's been a lot of bad meteorology and funny expectations about Monday/ Tuesday. Synoptically, the setup remains favorable for severe convection and flash flooding. Those who latch on to different numbers and indices each run and lose sight of the Synoptics will have forecasts and expectations that vary wildly from run to run.

Link to comment
Share on other sites

Exactly... Fropa slowed down. We thought the gfs timing was bogus.

As for the SPC I really don't judge how a threat changes based on what another forecaster who I don't know decides to do.

I feel like there's been a lot of bad meteorology and funny expectations about Monday/ Tuesday. Synoptically, the setup remains favorable for severe convection and flash flooding. Those who latch on to different numbers and indices each run and lose sight of the Synoptics will have forecasts and expectations that vary wildly from run to run.

That's why I have to give you credit for sticking to your guns and being consistent about your expectations for Monday/Tuesday. Let's see how it plays out.

Cheers.

Link to comment
Share on other sites

Exactly... Fropa slowed down. We thought the gfs timing was bogus.

As for the SPC I really don't judge how a threat changes based on what another forecaster who I don't know decides to do.

I feel like there's been a lot of bad meteorology and funny expectations about Monday/ Tuesday. Synoptically, the setup remains favorable for severe convection and flash flooding. Those who latch on to different numbers and indices each run and lose sight of the Synoptics will have forecasts and expectations that vary wildly from run to run.

 

One thing to also keep in mind (not that your're not ...just sayin' for the general reader)  is that the DPs are going to be pooled pretty well from the SE-MA and into New England, and with that comes an elevated land-scape of volitility  Optimistic ceilings in the morning can lead to ...itchy trigger fingers in during the afternoon, and higher CAPE has the advantage of having higher negative CAPE as exhaust ;)   Also, that a conditionally unstable environment can explode with little CIN and just about any increase in 700-500mb wind. 

 

Even if it see TXT now, they could expand that right on up and need little reason to do so with that set up. 

Link to comment
Share on other sites

SPC isn't even giving us 5% probs on Tuesday.

 

attachicon.gifday3.gif

 

O - kay.  so what-

 

SPC just made my point for tomorrow... Earlier they were well SW of us, but they just updated and now Monday's looking better for them... for whatever reason. I haven't delved into their forecast philosophy on this thing, just sayin.

 

day2otlk_1730.gif?1405279711396

Link to comment
Share on other sites

Heh, just got down saying this to y'all via Ryan:

 

THE SLIGHT RISK AREA
WAS EXTENDED NWD ACROSS SRN NEW ENGLAND WHERE 35-40 KTS OF SHEAR
WILL BE PRESENT BY AFTN AND HEATING OF LOWER 70S DEW POINTS
WILL
SUPPORT MLCAPE OF 1000-1500 J/KG.

 

With so much volitility - to re-iterate, a light increase in mid level velocities can make things pop.

Link to comment
Share on other sites

Why is everyone so infatuated with SPC? Who gives an F what they have.

 

Because they have valid insights developed off of superior education and advanced technology/computing power at their disposal, and can boast better verification scores over most other agencies over the longer term performance profile.... 

 

Any questions?   

 

And no one has demo'ed infatuation with them -- though I suspect you are just speaking hyperbole.  Even so, they are not a bad guide-line to base-line one's expectation, then build from there.  Certainly for people who live in Connecticut that don't know what the f they are doing at all ...  

Link to comment
Share on other sites

Gotta remember the SPC is in place more for large scale and widespread severe weather events as opposed to more localized threats or localized setups...those events/setups the local WFO's will usually carry much more weight.  

 

With that said, as for Tuesday, I am shocked we don't see at least 5% probs in place, however, for tomorrow I have no problems with how they are handling the situation.  Given the consistency/agreement within the guidance of us seeing at least 1500 J/KG of SBcape and perhaps as much as 1000 J/KG of MLcape, they feel that was significant enough when coupled with the shear to extend the slight risk into SNE.  

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

Guest
This topic is now closed to further replies.
  • Recently Browsing   0 members

    • No registered users viewing this page.

×
×
  • Create New...