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Central/Western Summer Medium/Long Range Discussions


Srain

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Tuesday has a ridiculous ceiling along the boundary near the KS/NE border, especially by 2014 standards. The only thing I'm not liking right now is that almost every model has widespread precip ongoing through the day N of said boundary. One date this setup reminds me of in some ways (though there are certainly large differences, too) is 17 June 2009, which I recall also having morning storms in the same area. If there's a decent window for insolation along the boundary, a prolific storm or two seems like a good bet.

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Tuesday has a ridiculous ceiling along the boundary near the KS/NE border, especially by 2014 standards.

 

I like how storm motions are going to favour storms moving along/parallel to the boundary rather than across it.

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Had to save some of the 18z NAM soundings for posterity's sake near the WF on Tuesday (no matter how unreliable the model is).

 

Local AFDs for Tuesday...

 

OAX:

A BREAK IN THE CONVECTIVE ACTIVITY SHOULD OCCUR ON MONDAY AND
MONDAY NIGHT...WITH THE NEXT ROUND OF SEVERE WEATHER LIKELY ON
TUESDAY. FLOW BECOMES MORE ZONAL BUT FASTER...WITH THE BIG CHANGE
BEING A SIGNIFICANT INCREASE IN DEEP LAYER SHEAR. MOST
DETERMINISTIC MODELS AGREE ON A DEEP SURFACE LOW FORMING IN
EASTERN COLORADO WITH A WARM FRONT MOVING FROM NORTHERN KANSAS
INTO SOUTHERN NEBRASKA. SHORTWAVES MOVING THROUGH THE FAST ZONAL
FLOW WILL AID IN LARGE SCALE ASCENT. AIRMASS WILL REMAIN MOIST AND
QUITE UNSTABLE. WARM FRONT WILL FOCUS ORGANIZED CONVECTION WITH
GOOD POTENTIAL FOR LONG LIVED MESOCYCLONES AND PLENTY OF LOW LEVEL
SHEAR. SEE SPC DAY4-8 DISCUSSION FOR ADDITIONAL INFO.

 

 

GID:

GETTING FURTHER INTO THE WORK WEEK...PLENTY OF UNCERTAINTIES TO WORK
OUT IN THE FORECAST. 24 HRS AGO IT APPEARED THE NEXT BEST CHANCE FOR
THUNDERSTORMS MIGHT COME WED/THUR...BUT LATEST RUNS HAVE MOVED THE
MORE INTERESTING PERIOD UP TO TUES/TUES NIGHT. THE REMAINDER OF THE
LONG TERM PERIOD THROUGH FRIDAY SHOWS THE REGION UNDER GENERALLY
ZONAL FLOW IN THE UPPER LEVELS...THANKS TO ELONGATED HIGH PRESSURE
OVER THE FAR SRN CONUS...AND THESE PERIODIC DISTURBANCES MOVING
THROUGH. THE CONCERN ON TUESDAY LIES WITH THE NEXT OF THESE
DISTURBANCES MOVING TROUGH...WITH THE POTENTIAL FOR THE MAIN SFC
WARM FRONT DRAPED THROUGH THE CWA...PROVIDING A FOCUSING MECHANISM
FOR DEVELOPMENT...MAINLY TUES AFTERNOON/EVENING. AT THIS POINT THE
HIGHER POPS ARE ACROSS THE NRN HALF OF THE CWA...BUT WILL SEE HOW
MODELS TREND WITH THE TIMING/LOCATION OF THE SYSTEM AND SFC BOUNDARY
OVER THE UPCOMING RUNS...ITS STILL SEVERAL PERIODS OUT BUT IF THINGS
REMAIN SIMILAR POPS WILL NEED TO BE RAISED.

 

 

TOP:

Tuesday...Incoming high pressure helps reinforce the surface
boundary across the CWA by early Tuesday. Front then gets a boost
back to the north as low pressure develops across the high plains
through the day. How far north this boundary can retreat will have
an impact on where storms develop on Tuesday afternoon. NAM and
GFS hold on to some degree of a cap across the southern portions
of the area but becomes very weak near the I70 corridor in the
middle afternoon. Atmosphere is strongly unstable with SBCAPE
3500J/kg and 0-6KM bulk shear running 50-60kts for surface based
parcels. It will be a race between the warmer temperatures aloft
as to where storms initiate, with models suggesting northern two
tiers are greatest risk with all modes of severe weather possible
in the afternoon and evening hours.
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Yeah some of the forecast hodos are wallpaper material. 

 

A few I pulled had SRH >700 m2/s2 with near 5000 J/kg of uncapped SBCAPE (over 3500 J/kg MLCAPE), silly stuff.

 

Oh, and >70 kts of 0-6 km shear on top of that.

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im gonna have to see if i can get Tuesday off, if model trends continue, especially since I wouldnt have to venture too far from my apartment.   Note to any chasers who will be in or around Lincoln then, there is tons of construction in town, On 70th street, Cornhusker hwy from 48th to the i-80 exit (399), then several areas down to 1 lane 

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GFS came south at 18z, might be a bit of a problem since warm mid level temperatures are gonna be an issue with southward extent. Interesting to note that the GFS has suffered from grid scale feedback for the past several runs though.

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1500 m^2/s^2 of 0-3 km helicity on the 18Z GFS? Heh heh. At least that area is thermonuclearly capped by then.

 

Looking to where storms actually have the possibility of forming, modeled ML CAPE >2500 J/kg and 0-3 km helicities >400 m^2/s^2 allude to an explosive environment for storms Tuesday afternoon.

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The NB/KS area looks pretty interesting. Just to cherry pick the raw GFS parameters for KLSN at 03Z on 6/4...STP of 15, 0-1km EHI of 10, VGP of 0.82. 60+ kts of bulk shear of which most of that is in the 0-1 km layer. There's definitely a big cap in place, but the GFS still pops convection off in that KLSN area anyway. The amount of shear in the lowest 1 km after the nocturnal low level wind maximum ramps up is quite astonishing.

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The low level shear/helicity forecasted Tuesday afternoon/evening is absolutely amazing, any mesocyclones that go off in those types of wind fields will go nuts in a hurry. Still a bit concerned about the warm nose around 700 mb, but it's the type of environment where just one storm could steal the show.

 

I've actually had to double and triple check soundings making sure what I have been reading is right.

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Not much mention of tornadoes in the D3, mostly focusing on the MCS threat.

 

I noticed that as well. Considering this is easily the best plains setup of 2014 thus far (even with concerns) I'm surprised at the lack of more than one mention of tornadoes in the entire outlook. We'll see how things evolve today as we get into range of the higher resolution model guidance (namely the 4-KM NAM). I can already say there are a ton of chasers planning to be out on Tuesday. After all, this is 2014. 

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It looks like the dry line could be too capped so that explains why the SPC is more interested in the MCS risk along the theta-e boundary to the north. The MCS indicators are pretty high, but so are the supercell/tornado indicators. Since the wind shear vectors are going to be more parallel to the boundary up there I would think the MCS risk trumps the discrete supercell risk in this case. But, even the hypothetical derecho would probably have a substantial leading edge tornado risk with the setup I'm seeing. Thoughts?

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Regardless of the D3 outlook, most of the area AFDs are hitting the tornado threat harder than SPC. Upper level flow is actually quite good near the WF unlike 5/11 so this could lead to longer maintenance of favorable storm modes.

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The 12Z ECMWF shows an incredibly deep, progressive (for mid-June) longwave trough pattern setting up out West in the long range.

 

That would almost certainly result in a very active severe weather pattern assuming the trough doesn't get stuck.

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That would almost certainly result in a very active severe weather pattern assuming the trough doesn't get stuck.

 

And there remains the big question. 500 mb heights remain well in excess of 588 dam out ahead of the trough on the model run, so that monster trough very well could get stuck so to speak out in the west. Ten days out is forever in the meteorological world, but against my better judgement, this model run has me salivating.

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