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JULY 2012 Severe Weather /Convection Discussion


NEG NAO

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That sounding is marginal at best. A minimum of 1500 j/kg of CAPE is needed to sustain severe convection; however, that only shows 1100 for tomorrow. And the LI is only -4*C. We need a minimum of -6*C for severe hail. But some large-scale ascent can compensate for this.

ughhh barring some wholesale changes in this system tommorow, its gonna be north and south of us cashing in with maybe some isolated severe in our neck of the woods....fingers crossed

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ughhh barring some wholesale changes in this system tommorow, its gonna be north and south of us cashing in with maybe some isolated severe in our neck of the woods....fingers crossed

I agree pretty much. Also, if the modeled shear with the combined 40-50 kt. of 700 mb westerly flow pan out with an impressive jet streak just to our north, it will prove to be too powerful for our lackluster SBCAPE and MLCAPE to handle. Thus, most of our storms will be sheared, low-topped and an elevated mess. I'd take 3000+ j/kg of MLCAPE combined with 30 kt of bulk shear any day over this progged setup.

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I agree pretty much. Also, if the modeled shear with the combined 40-50 kt. of 700 mb westerly flow pan out with an impressive jet streak just to our north, it will prove to be too powerful for our lackluster SBCAPE and MLCAPE to handle. Thus, most of our storms will be sheared, low-topped and an elevated mess. I'd take 3000+ j/kg of MLCAPE combined with 30 kt of bulk shear any day over this progged setup.

absolutely, but tommorow i dont think is gonna be for us, if we do get something id be surprised. who knows we may get something, just gotta wait till tommorow to know for sure whats going on

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SPC Day 1 Outlook: non-hatched 15% hail, 30% wind - highest probabilities yet for our area this year. If modeled shear becomes a bit more directional, helicity increases and/or storms does not become outflow-oriented, then we could be included in 2% or 5% tornado risks in later outlooks. If our LI goes below -6*C and we get sufficient cape in the hail-producing layer, then our hail probabilities could increase to 30%.

DAY 1 CONVECTIVE OUTLOOK  

   NWS STORM PREDICTION CENTER NORMAN OK

   1258 AM CDT SAT JUL 07 2012

  

   VALID 071200Z - 081200Z

  

   ...THERE IS A SLGT RISK OF SVR TSTMS FROM OH TO THE NORTHEAST...

  

   ...SYNOPSIS...

   UPPER-LEVEL ANTICYCLONE THAT HAS PERSISTENTLY BEEN ANCHORED OVER THE

   LOWER MO VALLEY WILL SUBSIDE AND ELONGATE LATITUDINALLY FROM THE

   CNTRL HIGH PLAINS TO THE SRN APPALACHIANS BY EARLY SUN AS RIDGING

   BEGINS TO BUILD IN THE WEST.  A MID-LEVEL SPEED MAX OVER THE UPPER

   GREAT LAKES/SERN CANADA WILL BECOME CENTERED ACROSS SRN NEW ENGLAND

   INTO NY BY THIS AFTERNOON. AT THE SURFACE...A SLOW-MOVING COLD FRONT

   SHOULD EXTEND FROM THE LOWER GREAT LAKES WWD TO THE CNTRL HIGH

   PLAINS THIS AFTERNOON.

  

   ...NORTHEAST/UPPER OH VALLEY...

   A COMPLEX SEVERE SETUP IS ANTICIPATED WITH RELATIVELY NARROW OVERLAP

   OF THE MOST FAVORABLE KINEMATIC PARAMETERS WITH THE BEST

   THERMODYNAMIC ENVIRONMENT AMIDST A WEAKLY FORCED LARGE-SCALE

   PATTERN.

  

   A CLUSTER OF ELEVATED TSTMS MAY BE ONGOING AT 12Z OVER PORTIONS OF

   THE LOWER GREAT LAKES...THAT WILL PROBABLY WEAKEN AS IT EVOLVES

   E/SEWD DURING THE MORNING HOURS. STRONG HEATING SHOULD RESULT IN

   TEMPERATURES REACHING INTO THE MIDDLE TO UPPER 90S IN THE WARM

   SECTOR...WHILE MODEST LOW-LEVEL WLYS AID IN ADVECTING RICHER

   BOUNDARY LAYER MOISTURE FROM THE MIDWEST. WITH MID/UPPER-LEVEL LAPSE

   RATES NOT EXPECTED TO BE STEEP...CONSENSUS OF GUIDANCE SUGGESTS

   BUOYANCY WILL BE WEAK FROM THE HUDSON VALLEY INTO SRN NEW ENGLAND.

   HOWEVER...STRONGEST MID-LEVEL FLOW WILL BECOME CENTERED IN THIS

   REGION...TO AROUND 50 KT AT 700 MB BY 21Z. ALTHOUGH CONVERGENCE

   ALONG THE FRONT AND PRE-FRONTAL TROUGH MAY REMAIN WEAK...WIDELY

   SCATTERED TSTMS SHOULD FORM DURING THE AFTERNOON. WITH STEEP

   LOW-LEVEL LAPSE RATES AND MODERATE TO STRONG DEEP-LAYER

   SHEAR...MULTICELL TO SUPERCELL STRUCTURES ARE PROBABLE...ESPECIALLY

   ACROSS PA INTO FAR SERN NY AND NJ. HERE...THE GREATEST POTENTIAL FOR

   A SMALL MCS WITH EMBEDDED BOWING SEGMENTS SHOULD EXIST WITH PRIMARY

   RISKS OF DAMAGING WIND AND SEVERE HAIL.</p>

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SPC Day 1 Outlook: non-hatched 15% hail, 30% wind - highest probabilities yet for our area this year. If modeled shear becomes a bit more directional, helicity increases and/or storms does not become outflow-oriented, then we could be included in 2% or 5% tornado risks in later outlooks. If our LI goes below -6*C and we get sufficient cape in the hail-producing layer, then our hail probabilities could increase to 30%.

DAY 1 CONVECTIVE OUTLOOK

NWS STORM PREDICTION CENTER NORMAN OK

1258 AM CDT SAT JUL 07 2012

VALID 071200Z - 081200Z

...THERE IS A SLGT RISK OF SVR TSTMS FROM OH TO THE NORTHEAST...

...SYNOPSIS...

UPPER-LEVEL ANTICYCLONE THAT HAS PERSISTENTLY BEEN ANCHORED OVER THE

LOWER MO VALLEY WILL SUBSIDE AND ELONGATE LATITUDINALLY FROM THE

CNTRL HIGH PLAINS TO THE SRN APPALACHIANS BY EARLY SUN AS RIDGING

BEGINS TO BUILD IN THE WEST. A MID-LEVEL SPEED MAX OVER THE UPPER

GREAT LAKES/SERN CANADA WILL BECOME CENTERED ACROSS SRN NEW ENGLAND

INTO NY BY THIS AFTERNOON. AT THE SURFACE...A SLOW-MOVING COLD FRONT

SHOULD EXTEND FROM THE LOWER GREAT LAKES WWD TO THE CNTRL HIGH

PLAINS THIS AFTERNOON.

...NORTHEAST/UPPER OH VALLEY...

A COMPLEX SEVERE SETUP IS ANTICIPATED WITH RELATIVELY NARROW OVERLAP

OF THE MOST FAVORABLE KINEMATIC PARAMETERS WITH THE BEST

THERMODYNAMIC ENVIRONMENT AMIDST A WEAKLY FORCED LARGE-SCALE

PATTERN.

A CLUSTER OF ELEVATED TSTMS MAY BE ONGOING AT 12Z OVER PORTIONS OF

THE LOWER GREAT LAKES...THAT WILL PROBABLY WEAKEN AS IT EVOLVES

E/SEWD DURING THE MORNING HOURS. STRONG HEATING SHOULD RESULT IN

TEMPERATURES REACHING INTO THE MIDDLE TO UPPER 90S IN THE WARM

SECTOR...WHILE MODEST LOW-LEVEL WLYS AID IN ADVECTING RICHER

BOUNDARY LAYER MOISTURE FROM THE MIDWEST. WITH MID/UPPER-LEVEL LAPSE

RATES NOT EXPECTED TO BE STEEP...CONSENSUS OF GUIDANCE SUGGESTS

BUOYANCY WILL BE WEAK FROM THE HUDSON VALLEY INTO SRN NEW ENGLAND.

HOWEVER...STRONGEST MID-LEVEL FLOW WILL BECOME CENTERED IN THIS

REGION...TO AROUND 50 KT AT 700 MB BY 21Z. ALTHOUGH CONVERGENCE

ALONG THE FRONT AND PRE-FRONTAL TROUGH MAY REMAIN WEAK...WIDELY

SCATTERED TSTMS SHOULD FORM DURING THE AFTERNOON. WITH STEEP

LOW-LEVEL LAPSE RATES AND MODERATE TO STRONG DEEP-LAYER

SHEAR...MULTICELL TO SUPERCELL STRUCTURES ARE PROBABLE...ESPECIALLY

ACROSS PA INTO FAR SERN NY AND NJ. HERE...THE GREATEST POTENTIAL FOR

A SMALL MCS WITH EMBEDDED BOWING SEGMENTS SHOULD EXIST WITH PRIMARY

RISKS OF DAMAGING WIND AND SEVERE HAIL.</p>

In other words if everything changes, lol. No way you'll see a 5% tor, let alone a 2% in all likelihood.

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NAM soundings are not impressive. Let's see how the day unfolds. If we see a small MCS form, that would help. It won't be individual storms. Cape has really backed off the last few days but we do have good shear, so if we get better cape, that would be good. 00Z sounding is big.

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I think we'll be more unstable than what the NAM suggests. We already have around 7.0 C/km mid-level rates. We'll have to watch convective debris from the north, though:

this is ahead of the front though that's the problem.

A lot of clouds today, high temps in trouble?

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The latest NAM is hinting that storms will blossom in the I-80 to I-78 corridor of NNJ then move ESE from there

where the 700 mb jet hits the higher instability.

our best shot is 0-3z tonight. i expect a lot of posts calling bust before then
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Just a quick map I whipped together, but I'm very concerned about NE PA and that could spill over into portions of SE NY and N NJ. I think we could see some powerful storms develop later on, but it will be interesting to see how the current activity in western NY affects that. Severe weather parameters, including spiking dew-points I think put portions of NE PA into the sweet spot.

post-533-0-53039100-1341673021_thumb.png

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best chance of storms is clearly with the complex droping SE from the finger lakes, that should impact the area 2-4pm

Weathergun says HRRR dissipates it. What do over models say? Looks like a new complex forms on the NAM judging from its farther west positioning.

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This is where things get interesting. HRRR breaks it down and then sparks a stronger one by mid-afternoon.

If the current complex hangs on now, that might diminish the threat of a more severe one later.

If the complex breaks down, that could allow further destabilization of the column and a higher severe threat for mid-late afternoon.

actually if it moves through at the current rate some spots could very well see two rounds of strong storms

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actually if it moves through at the current rate some spots could very well see two rounds of strong storms

Quincy whats the chances of severe storms form NYC on east? Being that im from this area want to know if i should get excited lol. Looks like we could get something but not so sure

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Quincy whats the chances of severe storms form NYC on east? Being that im from this area want to know if i should get excited lol. Looks like we could get something but not so sure

I'm not sold on much severe weather east of the Hudson in NY/CT or from NYC metro on east, but we will still need to keep a close eye, especially if we can hang onto more sunshine and keep the current NY activity away

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