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Potential locally significant severe weather event Tuesday 5/24

earthlight

By earthlight,
in New York City Metro

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earthlight

earthlight

Posted
Posted

Short range forecast guidance is still coming into focus with the handling of a significant--but compact--shortwave trough which will be ejecting northeastward from the Mississippi Valley on Tuesday. This feature--interacting with a moderately unstable airmass characterized by MLCAPE upwards of 1000j/kg and elevated/MUCAPE in excess of 2000j/kg--will act as a significant forcing mechanism for the development of convection and strong to severe updrafts. Although 0-6km bulk shear and effective shear is lacking somewhat, the close proximity of a mesoscale surface low, owing to the very strong vorticity with the shortwave trough, will be suffice to support the development of organized strong to severe convection. The presence of the low pressure will also allow for favorable low level winds..which may support an isolated tornado or two in any supercells that can develop.

f48.gif

You can see this very intense shortwave, the warm sector, and the surface low above on the image from tonights 00z NAM. That being said, there is still a tremendous amount of uncertainty with this feature. Global models are much weaker with the feature--and the NAM itself has been highly inconsistent. If this feature does develop as modeled on tonight's NAM--the severe threat would in fact likely be somewhat widespread. However, if the shortwave is weaker, a more isolated threat for severe weather will likely exist. Worth watching, no doubt. SPC has highlighted the area in a 30% probability and a Slight Risk on the Day 2 Outlook.

day2.prob.gif

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earthlight

earthlight

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...NORTHERN MID ATLANTIC STATES INTO THE LOWER HUDSON VALLEY...

WEAK TO MODERATE DESTABILIZATION ALONG AND AHEAD OF THE

SOUTHEASTWARD ADVANCING COLD FRONT...AND WITHIN THE PRE-FRONTAL LEE

SURFACE TROUGH...IS EXPECTED TO PROVIDE THE FOCUS FOR VIGOROUS

CONVECTIVE DEVELOPMENT WITH THE APPROACHING UPPER IMPULSE TUESDAY

AFTERNOON. MODELS ARE A BIT MORE UNCLEAR CONCERNING THE STRENGTH OF

THE VERTICAL SHEAR...BUT IT SHOULD BE ENOUGH TO SUPPORT POTENTIAL

FOR ORGANIZED STORM CLUSTERS...AND ISOLATED SUPERCELLS MAY NOT BE

OUT OF THE QUESTION. THIS COULD IMPACT MUCH OF THE URBAN

CORRIDOR...FROM WASHINGTON D.C./BALTIMORE TO NEW YORK CITY...BEFORE

CONVECTION DIMINISHING/SPREADS OFFSHORE WITH UPPER FORCING BY

TUESDAY EVENING.

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weatherwiz

weatherwiz

Posted
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John,

What's your thoughts on that s/w? This is very interesting b/c this is the first any model has really picked up on this, if not the first time it's definitely much stronger than any past runs. Also interesting b/c the GFS does not really have this feature at all....or it's a much, much weaker version.

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earthlight

earthlight

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John,

What's your thoughts on that s/w? This is very interesting b/c this is the first any model has really picked up on this, if not the first time it's definitely much stronger than any past runs. Also interesting b/c the GFS does not really have this feature at all....or it's a much, much weaker version.

It's likely something convective and related to what's going on over the MS/TN Valleys. There will be an incredible amount of variance in regards to that feature, in all likelihood.

For what it's worth, the 00z RGEM has the feature as well. The mesoscale models seem to be picking up on something this evening.

If it does come to fruition, we could really light up Tuesday evening. That shortwave means serious business in a moderately unstable atmosphere as advertised by guidance tonight.

f48.gif

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weatherwiz

weatherwiz

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Yeah I was wondering if that was convective related b/c the mesoscale models are definitely picking up on this feature more. This could be VERY interesting b/c the areas of the stronger shear could actually be right along the areas that receive the greatest instability. While ML lapse rates will be rather modest they are not too bad, right around 6 C/KM but with that s/w (if it happens as modeled) there would be a nice area of stronger height falls which could really enhance upward motion.

Going to have to watch this extremely closely.

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earthlight

earthlight

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Yeah I was wondering if that was convective related b/c the mesoscale models are definitely picking up on this feature more. This could be VERY interesting b/c the areas of the stronger shear could actually be right along the areas that receive the greatest instability. While ML lapse rates will be rather modest they are not too bad, right around 6 C/KM but with that s/w (if it happens as modeled) there would be a nice area of stronger height falls which could really enhance upward motion.

Going to have to watch this extremely closely.

Agreed on all counts. And yes...it's going to need to be closely monitored. It doesn't look like the 00z Euro has any significant rainfall along the lines of the NAM or RGEM. Can't see the shortwave specifics for a few hours.

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weatherwiz

weatherwiz

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Agreed on all counts. And yes...it's going to need to be closely monitored. It doesn't look like the 00z Euro has any significant rainfall along the lines of the NAM or RGEM. Can't see the shortwave specifics for a few hours.

One thing that may not be necessarily good with that s/w wave is it may be accompanied by warmer mid-level temperatures which could really kill lapse rates even more and decrease some of the instability.

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Dark Energy

Dark Energy

Posted
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ANY time i see a strong vort/sfc low on a run i take it with a grain of salt. i would bet this doesnt show up on the 12z run or is weaker at best. doesnt mean it wont happen, but in a convective pattern, these kind of flukes happen all the time. reason why when i forecast in these patterns, i dont really go over 40 pops given run to run changes.

edit. - but, your topic title did say big bust potential, so that has no issues with me. good call.

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Mikehobbyst

Mikehobbyst

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The urban landcape will be converted and flooded with 4XLT Tees in the coming days from DC, PHL to NYC. The shorts which go below the knees are for another discussion. Tall tee city next stop. The weather gets nice and summery, and the fashion suffers, but better than suffering with east winds. I always ask to myself why that when skin and bones rocks the 4XL and takes this consumer good away from somebody that really could use the shirt and needs the size. Just baffles me everytime.

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6zNam

6zNam

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The urban landcape will be converted and flooded with 4XLT Tees in the coming days from DC, PHL to NYC. The shorts which go below the knees are for another discussion. Tall tee city next stop. The weather gets nice and summery, and the fashion suffers, but better than suffering with east winds. I always ask to myself why that when skin and bones rocks the 4XL and takes this

consumer good away from somebody that really could use

the shirt and needs the size. Just baffles me everytime.

Lol

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TheTrials

TheTrials

Posted
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Cue TheTrials to post about the storms staying away from NYC :lmao:

But really, no matter what, we will be dealing with a decent surface low and very nice moisture with no capping. Instabiliy wont be an issue. Game on :devilsmiley:

Hey, what can I say, severe storms in the spring for nyc points east is a low percentage call. And so far this year, I have been right as severe storms have stayed away from the city for various reasons.

I haven't looked into this event yet.

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weatherwiz

weatherwiz

Posted
Posted

Most mesoscale models have weakened the small area of vorticity pretty dramatically on the last run or two, which would keep the severe threat more isolated.

Man that was interesting to see on the 0z runs last night :lol:

There are several ways to go about this...there have been times in the past when one or two model runs hinted at something like this then they backed off it only for the day of the event for that solution to verify. I believe something like this may have occurred Tuesday, June 5th, 2007?

This is just something we might have to nowcast...I'd still definitely be very conservative on this but wouldn't totally give up hope. At least it's better than tracking 50F with stratus.

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earthlight

earthlight

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winner, ding ding ding. Good call.

It was well documented in the early posts that it was likely convective and not a stable feature.

What's your thoughts on that s/w? This is very interesting b/c this is the first any model has really picked up on this, if not the first time it's definitely much stronger than any past runs. Also interesting b/c the GFS does not really have this feature at all....or it's a much, much weaker version.

It's likely something convective and related to what's going on over the MS/TN Valleys. There will be an incredible amount of variance in regards to that feature, in all likelihood.

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CooL

CooL

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Hey, what can I say, severe storms in the spring for nyc points east is a low percentage call. And so far this year, I have been right as severe storms have stayed away from the city for various reasons.

I haven't looked into this event yet.

you really have been right with most of the severe weather threats so far staying west of nyc unfortunately :cry:

nam really backed off the instability tomorrow for some reason..3000 to <1000 cape, its probably a blip.

have you or anyone seen any of these videos out of Joplin? Holy crap...This is a video of the actual tornado gaining strength and size..very rapidly too.

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weatherwiz

weatherwiz

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you really have been right with most of the severe weather threats so far staying west of nyc unfortunately :cry:

nam really backed off the instability tomorrow for some reason..3000 to <1000 cape, its probably a blip.

have you or anyone seen any of these videos out of Joplin? Holy crap...This is a video of the actual tornado gaining strength and size..very rapidly too.

Yeah b/c it finally backed off it's insane interpretation of the dewpoints.

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weatherwiz

weatherwiz

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Posted

Yeah we're going to have a severe weather event with this system at some point. It's just a matter of when.

I totally agree, the entire country has just been getting pounded with this pattern and were finally starting to get late enough into the season to where it's much easier for us to get some good instability. This kind of reminds of of 1998 a bit.

Even the SPC SREF is picking up on a possible EML advection towards our region...it's quite interesting though the direction it's coming from, normally I'd think of a more WSW or WNW direction.

http://spc.noaa.gov/exper/sref/sref.php?run=2011052315&id=SREF_prob_H7_to_H5_LapseRate_7__

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