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Severe weather thread number ...I think X ?


Typhoon Tip

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Tonight is gonna be a wild night of model watching...wiz you should compile a list of model links and times worth looking at...just cause you love doing stuff like that haha

Yep. Although this looks to me like yet another one of those events in which subtle details are going to have major effects on the final outcome, particularly in regards to the tornado threat. How big will the morning MCS be and will it move out fast enough to let the BL thoroughly recover? Over how big an area? Where exactly will the WF eventually set up? And then there’s storm mode, how long will the late afternoon convection stay discrete? These things can’t really be predicted with all that much accuracy… I mean yeah, you can look at models till you’re blue in the face - and I admit I’ll probably be doing just that along with everyone else - but it’s almost inevitable things will look subtly different in the morning. An interesting day in store, that’s for sure.

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Noyes.. It wouldn't let me copy the link from Twitter

Thursday will be an extremely varied day across New England. Rain will fall in Northern New England periodically for much of the day, and with relatively cool and dry air preceding that rain, temperatures will likely remain in the 60s through the day for much of Northern VT, NH and much of Central and Western Maine. Farther south, at least some showers will spread from northwest to southeast during the morning into the afternoon, but these initial showers will lose their punch as they move east, meaning total rainfall amounts will likely be below .25" farther east from the morning/midday showers, and some outdoor plans that have a tent or allow for ducking in and out as showers come through, may be OK in these areas. Meanwhile, deep heat and humidity will surge northeast across the Ohio Valley and into the Northeast U.S., boosting temperatures into the 80s for southwest New England, and 90s farther southwest. Squarely in the warm, humid air of Ohio and Pennsylvania, this sets up a favorable scenario for strong thunderstorms with damaging straight-line wind. For the areas that just barely get into the warmth and humidity - likely Connecticut, Western MA, and the Southern Tier of NY - this leaves a precarious setup of a changing wind direction through the atmosphere with just enough heat and humidity to provide ample energy for thunderstorm development. This very well may result in the issuance of a Tornado Watch for the aforementioned area late Thursday into Thursday evening. Farther east, through the remainder of Southern New England, a somewhat rare phenomenon of thunderstorms continuing to develop through the first half of the night very well may unfold, meaning the very late evening or night may actually bring the most substantial severe weather potential farther east, though that's more touch-and-go as it depends on just how much of a push warmth and humidity has after sundown in these areas. Regardless, the Storm Prediction Center has made the rather rare move of placing these higher-risk areas into a "Moderate Threat" for severe weather, meaning a 45% chance of damaging storms near any given point in the area, indicated on the map below. Certainly, all interests in the Northeast will need to monitor weather updates Thursday through Thursday night. -Matt

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Noyes.. It wouldn't let me copy the link from Twitter

Regardless, the Storm Prediction Center has made the rather rare move of placing these higher-risk areas into a "Moderate Threat" for severe weather, meaning a 45% chance of damaging storms near any given point in the area, indicated on the map below. Certainly, all interests in the Northeast will need to monitor weather updates Thursday through Thursday night. -Matt

That is not what the risk means. The risk is a severe report within 25 miles of any given point.

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Wow..An early start from Forbes

Dr. Greg Forbes@DrGregForbes

There could be a morning derecho - widespread thunderstorm wind event - Thursday morning in NY, CT, MA, RI, north NJ, maybe by sunrise

Pretty irresponsible, if legitimate, from Mr. Severe Weather. I would have told the powers that be to stfu if they asked me to write a tweet like that.

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Yep. Although this looks to me like yet another one of those events in which subtle details are going to have major effects on the final outcome, particularly in regards to the tornado threat. How big will the morning MCS be and will it move out fast enough to let the BL thoroughly recover? Over how big an area? Where exactly will the WF eventually set up? And then there’s storm mode, how long will the late afternoon convection stay discrete? These things can’t really be predicted with all that much accuracy… I mean yeah, you can look at models till you’re blue in the face - and I admit I’ll probably be doing just that along with everyone else - but it’s almost inevitable things will look subtly different in the morning. An interesting day in store, that’s for sure.

Nice post. Agree with all of this.

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What are your thoughts on 18z runs?

The tornado threat is a bit more ambiguous with the 18z GFS run and probably lessened while the NAM remains threatening (basically SW CT / SE NY / N NJ is in for it). The best course of action, as you know, is to see how tonight's convection evolves.

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Finally time to really review things!

Holy crap...tomorrow has really been looking better and better with the past several set of models runs. Normally as we get closer things look worse and worse but not this time!

As for morning activity goes I think there almost certainly will be some sort of MCS that rolls through right along the front and where the axis of strongest MUcapes reside. Sfc instability is quite weak, however, very good dynamics so can't rule out a few strong embedded cells and going back to the past we probably can't rule out an isolated severe cell or two.

I don't think we really have much problems clearing out and we should be able to see moderate destabilization take place...both NAM/GFS have a MAJOR instability burst in just a short amount of time and this is great for eliminating any CIN.

What we're really going to have to watch for is if sfc winds back to the S/SSE...0-1km helicity is already forecasted to be dangerously high and backing these winds will just boost it even further. EHI values are ridiculous as well! We're also dealing with nearly fall-like dynamics aloft and as we saw on 6/1/12 in the mid-Atlantic fall-like dynamics with summer-like instability are a great recipe for a major outbreak.

If we can get discrete supercells to form and maintain I could see several tornado reports tomorrow along with some hail reports in the 2-3'' diameter range...this will all depend though on whether or not we can get maximized instability and keep those >200m2s2 0-1 and 0-3km helicity values.

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Early Morning MCS/Derecho are rare, but happen, well lets see what happen on May 31st, 1998, the Derecho lasted from the evening into the overnight into the afternoon hours the next day, that's an example right there

Early morning MCS are NOT rare and they actually prefer the overnight / early morning. But more importantly, what is the point of your post?

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The tornado threat is a bit more ambiguous with the 18z GFS run and probably lessened while the NAM remains threatening (basically SW CT / SE NY / N NJ is in for it). The best course of action, as you know, is to see how tonight's convection evolves.

Agreed. GFS is probably veering the winds too much near the warm front. Instability a bit more meh on the GFS but still sizable.

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If we can get discrete supercells to form and maintain I could see several tornado reports tomorrow along with some hail reports in the 2-3'' diameter range...this will all depend though on whether or not we can get maximized instability and keep those >200m2s2 0-1 and 0-3km helicity values.

I am looking for the enhanced warm front / gradient (aided by precip falling in the cool sector) and organized surface trough to get the tornadic potential realized. Otherwise, tomorrow becomes mainly a significant wind event and possibly multiple rounds.

Did you notice the increase in cyclonic vorticity 00-06z on the new runs? This vort has been getting more and more realized with each run. Is it possible we see multiple rounds of thunderstorms in N PA, S NY into southern New England?

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I am looking for the enhanced warm front / gradient (aided by precip falling in the cool sector) and organized surface trough to get the tornadic potential realized. Otherwise, tomorrow becomes mainly a significant wind event and possibly multiple rounds.

Did you notice the increase in cyclonic vorticity 00-06z on the new runs? This vort has been getting more and more realized with each run. Is it possible we see multiple rounds of thunderstorms in N PA, S NY into southern New England?

Yeah I mentioned this tonight on the air. Seems like we could see several rounds lasting past 00z. The initial tornado threat evolving into a damaging wind threat.

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Agreed. GFS is probably veering the winds too much near the warm front. Instability a bit more meh on the GFS but still sizable.

Yeah I can buy that argument about the 18z GFS run.

Yeah I mentioned this tonight on the air. Seems like we could see several rounds lasting past 00z. The initial tornado threat evolving into a damaging wind threat.

Agreed with these thoughts. This synoptic aid behind the first shot could keep things going into the late evening. We'll see...I would imagine we will have enough juice left.

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I am looking for the enhanced warm front / gradient (aided by precip falling in the cool sector) and organized surface trough to get the tornadic potential realized. Otherwise, tomorrow becomes mainly a significant wind event and possibly multiple rounds.

Did you notice the increase in cyclonic vorticity 00-06z on the new runs? This vort has been getting more and more realized with each run. Is it possible we see multiple rounds of thunderstorms in N PA, S NY into southern New England?

I wonder if we could see some of those classic looking rotating comma heads with any squall lines tomorrow? Setup looks really good for that.

Yes...I am beginning to think we could really be dealing with severe weather from early tomorrow afternoon right through the overnight period into early AM Friday. Some models keep well over 1000-2000 J/KG of Cape throughout the night and we still have impressive dynamics.

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Seems okay to me. He is just laying out possibilities. If the general public cannot read context and the msm wants to go after the histrionic "it could happen tomorrow" angle, that's not Forbes fault. Plus he probably got paid $200k in stock options to say it. ;)

You can lay out all the possibilities you want...hail flows, F4 in CT, swollen rivers, a blizzard....but in the land of reality, there is no evidence to support a high enough probability to mention derecho in the forecast tomorrow morning...even if it ends up happening.

I would imagine his work and reputation are worthier than a JB-like move.

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Agreed. GFS is probably veering the winds too much near the warm front. Instability a bit more meh on the GFS but still sizable.

I admittedly haven't looked at the GFS much (mostly the NAM) but a cursory glance down in NJ seems to show it lacking the EML that the NAM shows entirely (and hence lower lapse rates and less of a cap). Why would that be?

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I wonder if we could see some of those classic looking rotating comma heads with any squall lines tomorrow? Setup looks really good for that.

Yes...I am beginning to think we could really be dealing with severe weather from early tomorrow afternoon right through the overnight period into early AM Friday. Some models keep well over 1000-2000 J/KG of Cape throughout the night and we still have impressive dynamics.

The deep layer SRH will definitely do that to a line of thunderstorms and it is definitely a possibility (esp. with the first round). I agree with you and Ryan about the persistent threat into the evening with the current data we have.

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The deep layer SRH will definitely do that to a line of thunderstorms and it is definitely a possibility (esp. with the first round). I agree with you and Ryan about the persistent threat into the evening with the current data we have.

The other thing to we have to consider is there will be several distinct leftover boundaries from any morning activity. The million dollar question here is what will storms do when they interact with these boundaries? On a day like tomorrow you could have a supercell which has that tornadic look but not quite enough to generate one then all of a sudden it interacts with one of these boundaries and boom, you have yourself tornadic supercell riding right along the boundary and completely taking off.

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You can lay out all the possibilities you want...hail flows, F4 in CT, swollen rivers, a blizzard....but in the land of reality, there is no evidence to support a high enough probability to mention derecho in the forecast tomorrow morning...even if it ends up happening.

I would imagine his work and reputation are worthier than a JB-like move.

Social media is making the world much stupider.

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Yeah I can buy that argument about the 18z GFS run.

Agreed with these thoughts. This synoptic aid behind the first shot could keep things going into the late evening. We'll see...I would imagine we will have enough juice left.

18z nam bufkit has ewr at 95/72 1z tomorrow evening

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The other thing to we have to consider is there will be several distinct leftover boundaries from any morning activity. The million dollar question here is what will storms do when they interact with these boundaries? On a day like tomorrow you could have a supercell which has that tornadic look but not quite enough to generate one then all of a sudden it interacts with one of these boundaries and boom, you have yourself tornadic supercell riding right along the boundary and completely taking off.

This post right here...

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can't contribute anything to the discussion, but felt compelled to let you all know this is a great thread and i'm really enjoying the analyses...thanks to all who are participating!

same thing here on the discussion,but if any would like to add some information for us FD guys here it would be greatly appreciated.

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