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Hoosier

2017 Short/Medium Range Severe Thread

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As in previous years, this thread is for discussion of severe threats in the medium/long range, as well as small scale short term events that aren't thread worthy.

On Monday and Tuesday, a deep surface low will track into the Plains and move into Canada.  Moisture return looks so-so at this point, and it looks like we may not have quite as good of an EML this time.  Wind fields do look pretty decent.  All in all, given the aforementioned factors, I'm not that bullish on this system from a severe perspective in this region right now, but there may be at least some severe potential.

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12z NAM doesn't look terrible out west in the Plains on Monday.  Gets 60F dewpoints well north in KS with upper 50s as far as the IA/MN border.

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Yes, the plains have better parameters with this system Monday than in our area, Hoosier.  But I am already intrigued by Sat. March 11th and its potential for the Midwest at this very early stage.  At least the parade of storms continues.

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Looks like maybe a seasonally decent squall line event Monday afternoon/eve from southern MN down through IA into MO.  Wind profiles are pretty stacked from IA northward.  Some better profiles further south out of our sub towards southeast KS into OK.  Looks like dews increase enough to build some marginal surface cape immediately out ahead of the advancing cold front.  Very nice surface convergence along the cold front, so initiation looks like a given with the other ingredients in place.  Was a bit surprised SPC didn't have a PREDICTABILITY TOO LOW for Monday instead of the POTENTIAL TOO LOW they put up.  Should be a decent enough of a setup to get a few severe reports scattered along the advancing squall line IMO.

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57 minutes ago, cyclone77 said:

Looks like maybe a seasonally decent squall line event Monday afternoon/eve from southern MN down through IA into MO.  Wind profiles are pretty stacked from IA northward.  Some better profiles further south out of our sub towards southeast KS into OK.  Looks like dews increase enough to build some marginal surface cape immediately out ahead of the advancing cold front.  Very nice surface convergence along the cold front, so initiation looks like a given with the other ingredients in place.  Was a bit surprised SPC didn't have a PREDICTABILITY TOO LOW for Monday instead of the POTENTIAL TOO LOW they put up.  Should be a decent enough of a setup to get a few severe reports scattered along the advancing squall line IMO.

Agree

Question is how well this survives into our area.  The GFS is on the fast side and figuring on something slower like the ECMWF or NAM, the timing isn't favorable but the pressure gradient in the warm sector would suggest that nocturnal cooling may be slow.  Slower solution would likely allow for somewhat better moisture return.   

 

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Large marginal risk area for day 3

swody3_severeprob.png

 

The wind fields are really strong Monday night/Tuesday morning, so I wouldn't be surprised to see a threat continue farther east despite less favorable instability.

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The GFS has back to back ~980 mb lows next weekend, with the first one sort of acting as a sacrificial lamb and allowing for better moisture return for the second system. Interesting look but obviously too far out to put stock in any individual model solution.

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48 minutes ago, Hoosier said:

The GFS has back to back ~980 mb lows next weekend, with the first one sort of acting as a sacrificial lamb and allowing for better moisture return for the second system. Interesting look but obviously too far out to put stock in any individual model solution.

Like 4 runs in a row of something in that time frame, of course the Euro has a blizzard on the east coast at that time frame so who knows.

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DVN mentions the T word in their latest disco...

 

This storm system will be accompanied by a strong jet and narrow
zone of instability pooling head of the cold front - suggesting a
high-shear low-CAPE environment. Models are forecasting 0-1 km bulk
shear around 40 kts, 0-3 km shear vectors near 45 kts with some
perpendicular component to the line of convection, and sfc-based
instability of at least 500 J/kg). The greatest severe risks are
straight line damaging wind gusts and a few brief tornado spin ups.

 

This stuff will line up quickly at initiation, so we'll have to count on that sfc-1km shear to kink up the quickly advancing line in a few locations for any brief tor threat.  Looks like a decent wind threat though with lots of momentum just off the surface.  The storms will likely never be able to leave the fast moving cold front, so the squall line wind-shift looks to become the effective cold front right off the bat.

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1 hour ago, cyclone77 said:

DVN mentions the T word in their latest disco...

 


This storm system will be accompanied by a strong jet and narrow
zone of instability pooling head of the cold front - suggesting a
high-shear low-CAPE environment. Models are forecasting 0-1 km bulk
shear around 40 kts, 0-3 km shear vectors near 45 kts with some
perpendicular component to the line of convection, and sfc-based
instability of at least 500 J/kg). The greatest severe risks are
straight line damaging wind gusts and a few brief tornado spin ups.

 

This stuff will line up quickly at initiation, so we'll have to count on that sfc-1km shear to kink up the quickly advancing line in a few locations for any brief tor threat.  Looks like a decent wind threat though with lots of momentum just off the surface.  The storms will likely never be able to leave the fast moving cold front, so the squall line wind-shift looks to become the effective cold front right off the bat.

My appreciation for QLCS tors increased today when I attended spotter training and the met said that 40% of Indiana's annual count of tornadoes comes from spin ups in these lines.  Pays to be on guard and not dismiss these squall lines.

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14 hours ago, Indystorm said:

My appreciation for QLCS tors increased today when I attended spotter training and the met said that 40% of Indiana's annual count of tornadoes comes from spin ups in these lines.  Pays to be on guard and not dismiss these squall lines.

Yep, and they're likely a huge headache for the NWS offices as well, as they usually happen very quickly.  Have to constantly be checking higher tilts to see if there's anything starting to rotate in the mid-levels.  Sometimes you can see it show up there a scan or two before it shows itself down low.  

The NAM products continue to slow up the progression of the cold front tomorrow.  Now closer to what the EC has been forecasting all along.  GFS will likely end up being too fast.  The best chance for anything other than a brief QLCS spinup looks to take place down in southeast KS.  Mid-levels are more veered down there on the right side of the mid-upper jet, and the moisture is deeper there as well.  I'd like to see the shear vectors a little more veered in relationship to the front, but they're not terrible by any means.  Any storm that can stay discrete for awhile down in this area should have a decent chance to produce.  

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2 hours ago, Hoosier said:

12z GFS gets the surface low down to 970 mb near the Canada border (and lower north of there).  

Very impressive.  I like the fact that we have a very strong/strengthening surface low, but it's fairly far to the north.  It keeps surface flow relatively backed out ahead of the front, but with the surface low so far north there's nothing to keep the CF from crashing east/southeastward.  Would love if a secondary were to develop further south just to hold up the progression a bit in a given area.  Of course would love more instability as well lol, but at least there should be enough for some severe as far north as southeast Minnie.

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26 minutes ago, cyclone77 said:

Very impressive.  I like the fact that we have a very strong/strengthening surface low, but it's fairly far to the north.  It keeps surface flow relatively backed out ahead of the front, but with the surface low so far north there's nothing to keep the CF from crashing east/southeastward.  Would love if a secondary were to develop further south just to hold up the progression a bit in a given area.  Of course would love more instability as well lol, but at least there should be enough for some severe as far north as southeast Minnie.

SPC did add an enhanced risk area outside of the region, and also expanded the slight risk.

That somewhat backed flow you mentioned is a negative in one sense in that it keeps low level trajectories coming off the surface high longer, especially farther east, hence the narrowing moisture/instability plume with eastward extent.

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8 minutes ago, Hoosier said:

00z NAM has a narrow tongue of 1500+ J/kg CAPE into IA tomorrow. It has been more bullish on destabilization.

01z HRRR already has over 1900J/kg surface cape over northwest Iowa at 19z tomorrow per some forecast soundings.  Dews up close to 60 by that time as well.  

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10 minutes ago, cyclone77 said:

01z HRRR already has over 1900J/kg surface cape over northwest Iowa at 19z tomorrow per some forecast soundings.  Dews up close to 60 by that time as well.  

Conceivable that the ENH could be pulled north if these more unstable soundings are even remotely close.  The GFS is on another planet with instability but we'll see if 00z trends upward.

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The 0z NAM actually has a decent threat across IA/S. MN.

 

I might have gambled and chased it if I could. Actually like that area more than down south where the SPC has the ENH risk.

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16 minutes ago, Hoosier said:

Conceivable that the ENH could be pulled north if these more unstable soundings are even remotely close.  The GFS is on another planet with instability but we'll see if 00z trends upward.

Not going to be too difficult to pull out appreciable CAPE with the level of cooling aloft here (again). The lack of sub-tropical jet influence has really enhanced the lapse rates this year (as one would expect).

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The same areas in our sub that were starved for snow this winter are also getting the short end on the severe outbreaks.  This pattern just blows :thumbsdown:

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The same areas in our sub that were starved for snow this winter are also getting the short end on the severe outbreaks.  This pattern just blows :thumbsdown:


Definitely not entirely true.

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6 hours ago, Hoosier said:

Will be in a quiet period for a while but it's been an impressive start, especially with the northern reports.

2017_annual_map_all.gif

Extremely impressive to say the least.  Pretty cool graphic.  I also really like the SPC graphic display of the tornado/severe watch accumulation.

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9 hours ago, Hoosier said:

Will be in a quiet period for a while but it's been an impressive start, especially with the northern reports.

2017_annual_map_all.gif

 

9 hours ago, Jackstraw said:

The same areas in our sub that were starved for snow this winter are also getting the short end on the severe outbreaks.  This pattern just blows :thumbsdown:

 

9 hours ago, Chicago Storm said:


Definitely not entirely true.

No, but you have to admit that impressive as it is, there's a pretty good sucker hole over Central IL/IN.

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12 minutes ago, IWXwx said:

 

 

No, but you have to admit that impressive as it is, there's a pretty good sucker hole over Central IL/IN.

Hopefully carnage pays a visit to those areas soon enough. ;)

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7 minutes ago, IWXwx said:

 

 

No, but you have to admit that impressive as it is, there's a pretty good sucker hole over Central IL/IN.

Same for Lower Michigan outside of the first tier of counties. Of course it is early in the season so that is to be expected.

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3 minutes ago, Hoosier said:

Hopefully carnage pays a visit to those areas soon enough. ;)

We had our share of carnage here today, with three structure fires, including one that lit up a half block section of downtown, multiple power outages from trees being blown over (our asos had a 59 MPH gust), trees blocking roadways, a brick wall facade being blown over, and two trucks blown over on I 69. Otherwise, just a typical March day in Huntington County.

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