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Potential thunderstorms/svr thunderstorms Thread


tombo82685

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Real nice. :P

Yeah, the surface based instability has been getting shoved southward due to the earlier convection plus the east to southeast low-level flow. The cell that ramped up some in eastern Chester county not long ago turned southward as it was ingesting more unstable air in northern Delaware. We have limited rainfall totals so far in a PNS which are from Northampton county.

do you want some rain totals? ill call in my works total?

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Tstorm Watch Possible

mcd1753.gif

MESOSCALE DISCUSSION 1753

NWS STORM PREDICTION CENTER NORMAN OK

0424 PM CDT TUE JUL 26 2011

AREAS AFFECTED...ERN PA...SERN NY...CNTRL/NRN NJ

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 262124Z - 262230Z

THE THREAT FOR SVR STORMS COULD EXTEND TO THE ATLANTIC COAST...AND

AN ADDITIONAL WW MAY BE NEEDED SOUTH OF WW686/WW687...OR SWD WW

EXTENSION MAY BE NEEDED.

VISIBLE SATELLITE IMAGES DEPICT DEVELOPING CONVECTION ALONG A

PREFRONTAL CONVERGENCE AXIS STRETCHING SWWD FROM SERN NY INTO ERN

PA. WHILE INSTABILITY IS ONLY MARGINAL TO MODERATE...EFFECTIVE BULK

SHEAR MAGNITUDES OF 40 TO 50 KT WILL MAINTAIN A THREAT FOR ORGANIZED

MULTICELLULAR OR POSSIBLY SUPERCELLULAR STRUCTURES TOWARD THE

COAST...WITH ATTENDANT THREATS FOR DMGG WIND GUSTS AND POSSIBLY

MARGINALLY LARGE HAIL. THE THREAT MAY BE MITIGATED TO SOME DEGREE

OVER LONG ISLAND...WHERE THE STABLE MARINE LAYER WILL OFFER ENHANCED

MLCINH. THE GREATEST THREAT FOR SVR STORMS WILL BE ACROSS NRN PARTS

OF THE DISCUSSION AREA...WHICH WILL BE IN CLOSER PROXIMITY TO

STRONGER DEEP-LAYER ASCENT ASSOCIATED WITH A SHORTWAVE TROUGH

SWINGING THROUGH PARTS OF NEW ENGLAND.

..COHEN.. 07/26/2011

ATTN...WFO...OKX...PHI...BGM...CTP...

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ehh, not impressed with severe chances here. all 3 cape values are marginal AOA 1500 or less. Lift index is very marginal arouns -2.

MId level lapse rates arent even at 5degrees. BR numbers are nill

The only positives i see going are sufficient shear, and 8 degree low level lapse rates.downdraft cape is solid looking, but im inclined to say thats due to the low level lapse rates.

If its not the shear thats lacking, its the thermo's.

Looking at radar, not impressed yet. Worth keeping an eye on.Pwats arent terribly high, so that shouldn't waterload any updraft and help sustain any storm that can/does develop.

I think we're looking at a TTN north target area.

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Interesting little cells dropping SE into Chester/Mont Co. now. Lets see what they do.

What's even more interesting is to see how the outflow boundry from the NY cells interact with those cells, now dying, in the next

hour:http://synoptic.envsci.rutgers.edu/site/radar.php?&dix=anim&radar=Fort%20Dix%20Radar

Wonder if it will flare them up or downright kill em.

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What's even more interesting is to see how the outflow boundry from the NY cells interact with those cells, now dying, in the next

hour:http://synoptic.envsci.rutgers.edu/site/radar.php?&dix=anim&radar=Fort%20Dix%20Radar

Wonder if it will flare them up or downright kill em.

meh, one of the stronger cells moved overhead with no thunder and just sporadic large rain drops.

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Day 3 slight risk out for Monday, for some of the area. Wouldn't be surprised to see it expanded in the upcoming outlooks.

DAY 3 CONVECTIVE OUTLOOK

NWS STORM PREDICTION CENTER NORMAN OK

0200 AM CDT SAT JUL 30 2011

...THERE IS A SLGT RISK OF SVR TSTMS MON ACROSS PARTS OF THE

NORTHERN MID ATLANTIC COAST THROUGH THE HUDSON/CHAMPLAIN VALLEYS AND

MUCH OF NEW ENGLAND...

...NORTHEAST...

A PRE-FRONTAL BAND OF MID-LEVEL FORCING FOR UPWARD VERTICAL MOTION

MAY SUPPORT CONSIDERABLE THUNDERSTORM ACTIVITY ACROSS THE CHAMPLAIN

VALLEY THROUGH NORTHERN NEW ENGLAND DURING THE DAY MONDAY...WITH

ADDITIONAL STORMS POSSIBLY BECOMING NUMEROUS WITHIN A PRE-FRONTAL

SURFACE TROUGH ACROSS THE NORTHERN MID ATLANTIC COAST INTO SOUTHERN

NEW ENGLAND. DEEP LAYER MEAN FLOW AND SHEAR MAY BE SOMEWHAT

MARGINAL FOR SEVERE STORMS...BUT MODERATELY LARGE CAPE AND

RELATIVELY COOL MID-LEVELS MAY BE SUFFICIENT FOR HAIL AND

POTENTIALLY DAMAGING WIND GUSTS.

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Day 2 slight risk now includes all of E PA, and all of NJ, excluding far SJ.

DAY 2 CONVECTIVE OUTLOOK

NWS STORM PREDICTION CENTER NORMAN OK

1200 AM CDT SUN JUL 31 2011

VALID 011200Z - 021200Z

...THERE IS A SLGT RISK OF SVR TSTMS MON ACROSS PARTS OF THE

NORTHERN MID ATLANTIC COASTAL AREAS THROUGH THE HUDSON/CHAMPLAIN

VALLEYS AND MUCH OF NEW ENGLAND...

...NORTHEAST...

MODELS CONTINUE TO INDICATE THE PRESENCE OF RELATIVELY STEEP

MID-LEVEL LAPSE RATES AND THE DEVELOPMENT OF MODERATE CAPE MONDAY

AHEAD OF THE DIGGING UPPER LOW/TROUGH...ACROSS NORTHERN MID ATLANTIC

COASTAL AREAS THROUGH THE HUDSON/CHAMPLAIN VALLEYS AND MUCH OF NEW

ENGLAND. MID/UPPER FORCING FOR UPWARD VERTICAL MOTION SHOULD BE

SUFFICIENT FOR CONSIDERABLE THUNDERSTORM ACTIVITY. ALTHOUGH DEEP

LAYER FLOW AND SHEAR MAY BE GENERALLY MODEST...RELATIVELY COOL

MID-LEVEL TEMPERATURES WILL PROBABLY CONTRIBUTE TO FAVORABLE

THERMODYNAMIC PROFILES FOR HAIL AND POTENTIALLY DAMAGING WIND GUSTS

IN STRONGER STORMS.

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The MCS that comes through lays some sort of boundry.warm front set up for later that evening. Doesnt seem like the WF makes it north of Philly. but along it, shear is excellent. No real instability, but the NAM does have a precip maxima over us @ hr 51. Not sure if its convective feedback( 500 mb rel vort looks a little too strong)... Anyhow, mt. Holly had mentioned a scenario like this today in the AFD. 1 event at a time i guess.

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The MCS that comes through lays some sort of boundry.warm front set up for later that evening. Doesnt seem like the WF makes it north of Philly. but along it, shear is excellent. No real instability, but the NAM does have a precip maxima over us @ hr 51. Not sure if its convective feedback( 500 mb rel vort looks a little too strong)... Anyhow, mt. Holly had mentioned a scenario like this today in the AFD. 1 event at a time i guess.

Just my .02 -- we should have different threads for each event of note and leave this thread just to general banter about potential. This MCS is a real deal...just a question of where it goes.

post-105-0-63000000-1312275567.gif

SPC's WRF has a weakened (but still rainy) MCS moving in around 8 AM Wednesday FWIW. http://www.emc.ncep....d_1000m_f36.gif

FWIW, MCS' typically outrun computer guidance so it's possible that these storms get in around 3 AM locally and get out a bit earlier. Would not surprise me if we get some sun in the afternoon and outdo the GFS/NAM MOS from 0z (80 and 76, respectively). I don't think we hit 90 tomorrow but mid 80's is certainly within ballpark of reality in the city. Could also lead to some additional firing of storms in the PM as the NAM has depicted...

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Phlwx,

I saw that the nws had our high as 77. Doesn't seems like the wf will lift north of the area with their thinking. That could be a limiting factor later in day in regards to instability. Just something that could happen

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Phlwx,

I saw that the nws had our high as 77. Doesn't seems like the wf will lift north of the area with their thinking. That could be a limiting factor later in day in regards to instability. Just something that could happen

That's assuming the model timing is right...personally, knowing past history with MCS' they can often outrun the models. The warm front might not technically lift north of the region (might get to Philly) but I don't discount the potential for at least a midday sunny break and warmer temps than what MOS is spitting out IF (and that's a big if) the faster arrival plays out.

If the modeling is right, the temps will probably not hit 80 and we get storms during the morning and DE gets a 2nd round in the PM...I'm just throwing out there that the models could just as easily bust.

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I agree. The 0z nam seemed to have a few hours of cloud debris throughout the day, which seemed to limit diurnal heating. As usual , like you said, won't know untill tomorrow how it plays out.

But the prospect of having an mcs roll through would be a nice relief for everyone to get a little rain.

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