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Sept 11-12 Wednesday, Thursday Storm Threat


free_man

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yeah but it's akin to the kind of numbers that happen to our SW all summer long...while they just bake away and nothing happens. 

 

 

They'll be days and days of -15C LIs in Texas with nothing. Used to hate it...jsut seeing the clouds not able to muster any vertical depth.

 

 

The cap is an issue that has to be dealt with.

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SPC AC 091628   DAY 2 CONVECTIVE OUTLOOK     NWS STORM PREDICTION CENTER NORMAN OK   1128 AM CDT MON SEP 09 2013   VALID 101200Z - 111200Z   ...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF THE NORTHEAST   STATES...   ...NORTHEAST STATES...   A BROAD UPPER RIDGE WILL REMAIN OVER THE SOUTH-CENTRAL AND   SOUTHEASTERN UNITED STATES ON TUESDAY...WHILE A BAND OF STRONG   WESTERLIES EXTENDS FROM THE NORTHERN PLAINS INTO NEW ENGLAND.  A   STRONG SHORTWAVE TROUGH CURRENTLY OVER MN/ND IS FORECAST TO TRACK   ACROSS THE GREAT LAKES REGION AND INTO WESTERN NY BY 10/12Z.  MOST   MODEL SOLUTIONS INDICATE THAT AN MCS WILL BE ONGOING IN THIS REGION   AT THE BEGINNING OF THE FORECAST PERIOD...AND WILL PROPAGATE   EASTWARD ACROSS NEW ENGLAND DURING THE DAY.  THE TIMING OF THIS   SYSTEM IS A MAJOR COMPLICATION REGARDING THE SEVERE THREAT...SINCE   LOW LEVEL MOISTURE WILL NOT HAVE MUCH TIME TO RETURN AHEAD OF THE   MCS...AND CONSIDERABLE CLOUD COVER MAY EXIST PRECEDING THE   CONVECTION.  NEVERTHELESS...WIND FIELDS ARE FORECAST TO BE QUITE   STRONG OVER MUCH OF NY AND CENTRAL/NORTHERN NEW ENGLAND WITH SHEAR   PROFILES FAVORABLE FOR SUPERCELL/BOWING STORM STRUCTURES.  DESPITE   QUESTIONS REGARDING INSTABILITY...HAVE OPTED TO EXPAND SLIGHT RISK   AREA TO INCLUDE MORE OF VT/NH/ME.   IN THE WAKE OF THE MORNING SYSTEM...SUBTLE SHORTWAVE RIDGING WILL   TAKE PLACE ACROSS THE NORTHEAST STATES.  HOWEVER...STRONG   INSTABILITY MAY DEVELOP ALONG A BOUNDARY EXTENDING ROUGHLY ALONG THE   US-CANADIAN BORDER...WHERE FAVORABLE VERTICAL SHEAR WILL REMAIN.    CONVECTIVE INITIATION IN THIS REGION WILL LIKELY BE LIMITED IN AREAL   COVERAGE.  BUT ANY STORM THAT CAN FORM WILL POSE A RISK OF LARGE   HAIL AND DAMAGING WINDS.   ..HART.. 09/09/2013
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Heavy, heavy CIN

I understand what the concept of cinh is. I know marine air etc is where it likes to live.

 

I understand the lifting action and the rising of air and how that leads to storms etc. I guess I don't grasp mentally what cinh actually is. Is it simply the opposite of instability? What is it in the atmosphere? Is there different types?

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I will be ready, especially for a nice shelf rolling across the lake. It would of course be nice to get some discretes too. One thing I learned from the April 16th, 2011 historic tornado outbreak in NC (see my profile pic), is the local WFO was keyed in ahead of SPC so definitely watch those afternoon discussions.

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Damn looks good up here... I'm leading in a few hours to head south to CT till Wednesday evening though.  Hopefully don't miss like an F-2 moving through the heart of BTV's warning area, lol.  I already got my 60mph straight-line winds and no power for 3 days earlier this summer, so I'm good on the heavy damage stuff.

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I understand what the concept of cinh is. I know marine air etc is where it likes to live.

 

I understand the lifting action and the rising of air and how that leads to storms etc. I guess I don't grasp mentally what cinh actually is. Is it simply the opposite of instability? What is it in the atmosphere? Is there different types?

 

CINH is just convective inhibition, so yes, it is like the opposite of Cape (you could think of it that way).  It's different than marine tainted air b/c marine air stabilizes the llvl's and/or the sfc.  In order to break the CIN you need to reach the convective temperature or have some sort of lifting mechanism.  Depending on how strong the CIN is you might need some really strong forcing or very little.  

 

To get significant severe though you really want strong CIN in place b/c it allows for extreme amounts of instability to bottle up so when that cap breaks you get explosive updraft development and a storm can go from a single CU to a organized severe storm within minutes.  The strong CIN can also prevent numerous development which allows for those discrete cells to just live forever and remain very potent.

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Thursday still is very interesting for the rest of us.  Could get overshadowed if anything substantial happens tomorrow and/or Wednesday but Thursday is definitely in the cards too...may be less significant overall but still a solid threat

Wondering what we see down here; obviously W CT/W MA better shot than us in the east.

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Wondering what we see down here; obviously W CT/W MA better shot than us in the east.

 

Thursday would likely be more of a wind/hail threat.  We do have to worry about timing issues though as latest guidance slows down the front/trough a bit.  However, the amount of forcing along this front is pretty insane, more typical of mid to late October and while we may lose sfc instability there is a decent amount of elevated cape.  

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Somewhat OT but still on the convection topic, does anybody remember the 10/4/11 flooding on the north shore? Some areas got 5" of rain in the early morning hours, a cell with torrential downpours just sat over the area for hours. Anyone remember what the atmospheric conditions were for that setup?

 

Guessing low shear if the storm just sat but I don't really remember.

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I guess in SNE as Scooter said re: Tuesday PM..we can hope the complex bends right. You can think of many times when things were modeled to hit us and ended up going to our SW. Not likely..but the option remains there

 

it is something to keep in mind.  Models do struggle with handling MCS activity and they can end up being further SW than modeled.  They also typically love to ride the highest instability/theta-e axis so it's important to watch where those are setting up.

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Very unusual synoptic scenario about to unfold over the next two days.  

 

In one sense we have this very, very dry air in place, but then just two days later we have to flood the area with DPs in the upper 60s and kinetic temperature potential into the mid 90s.   One is left to wonder how such an atmospheric turn-around can transpire without consequence.  It's very romantic to think along such dramatic themes, but... sometimes conditions just flip around without consequence, just the same.  

 

I recall something like this occurring much earlier in the summer, with a 1 day turn around going from dry in the 70s to 90s the next day.  I remember seeing the rather densely packed thickness gradient over western NE modeled for a 12z time period, and then noting that by 00z the following evening the gradient was modeled well E of Logan.  

 

Edit: I think I found it... it was those last 2 days in May into June.  Went from 70 at logan, to 88 than 94, boom boom turn around

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I'd have to think any tail end stuff tomorrow in NH or NE MA would be elevated.  I can see echoes really struggling in that environment. 

 

More for Tuesday night, but yeah I just mention it as a small possibilty since there is still an isentropic push thanks to the instability spike aloft. The dynamics are all north though, but it wouldn't shock me for some sct stuff to clip nrn Essex county.  Also, some weakening shwrs/tstms may approach srn VT and the Berks tomorrow morning.

 

I haven't seen an instability push like this in a long time.

 

 

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More for Tuesday night, but yeah I just mention it as a small possibilty since there is still an isentropic push thanks to the instability spike aloft. The dynamics are all north though, but it wouldn't shock me for some sct stuff to clip nrn Essex county.  Also, some weakening shwrs/tstms may approach srn VT and the Berks tomorrow morning.

 

I haven't seen an instability push like this in a long time.

 

attachicon.gifavn_850_theta-e_24.gif

 

attachicon.gifavn_30_rh.gif

 

Very impressive.

 

I wonder if tomorrow evening in CNE we could get something to fire on the outflow boundary from the convection to the north. 

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Very impressive.

 

I wonder if tomorrow evening in CNE we could get something to fire on the outflow boundary from the convection to the north. 

 

I also wonder if whatver comes through Tuesday into Tuesday night leaves a remaining boundary over that region. Might serve for a focal point Wednesday despite heights pretty darn high. These setups are always difficult to figure out because these things can be off a few hours and there goes a forecast. The region up there is primed for one to perhaps three good events from tomorrow into Thursday.

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I also wonder if whatver comes through Tuesday into Tuesday night leaves a remaining boundary over that region. Might serve for a focal point Wednesday despite heights pretty darn high. These setups are always difficult to figure out because these things can be off a few hours and there goes a forecast. The region up there is primed for one to perhaps three good events from tomorrow into Thursday.

I'm just glad the questions aren't focused around morning cloud debris, instability concerns, and or crapvection for once.

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I'm just glad the questions aren't focused around morning cloud debris, instability concerns, and or crapvection for once.

 

Hopefully any MCS debris clouds don't muck up tomorrow, but not sure it matters with the warm push. The morning stuff may target VT with the initial surge and then we'll see what happens in the aftn.

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Hopefully any MCS debris clouds don't muck up tomorrow, but not sure it matters with the warm push. The morning stuff may target VT with the initial surge and then we'll see what happens in the aftn.

Shouldn't be an issue...luckily with EML advections they tend to clear out the war sector

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