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June 11-17 Severe Threats


Quincy

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Beyond the MCS/damaging wind potential tomorrow, some amplification the upper level pattern should support an elevated threat of severe weather through Saturday. Storm mode remains to be seen beyond tomorrow's largely linear threat, but given increasing deep layer shear and good turning with height (WNW in the upper levels), I wouldn't be surprised if the supercell potential increases a bit by Friday and Saturday over portions of Iowa/Kansas/Missouri/Nebraska.

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10 minutes ago, Quincy said:

Beyond the MCS/damaging wind potential tomorrow, some amplification the upper level pattern should support an elevated threat of severe weather through Saturday. Storm mode remains to be seen beyond tomorrow's largely linear threat, but given increasing deep layer shear and good turning with height (WNW in the upper levels), I wouldn't be surprised if the supercell potential increases a bit by Friday and Saturday over portions of Iowa/Kansas/Missouri/Nebraska.

I've been interested in Friday/Saturday on the GFS for quite a few days now. Both seem like days where *if* discrete supercells develop, then a few tornadoes could easily occur given the progged wind fields. 

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3 hours ago, jojo762 said:

I've been interested in Friday/Saturday on the GFS for quite a few days now. Both seem like days where *if* discrete supercells develop, then a few tornadoes could easily occur given the progged wind fields. 

Friday is probably the more intriguing of the two days, with a decent supercell/tornado threat near the warm front where winds are backed fairly significantly. Assuming the NAM/GFS have a decent handle on LL moisture, some moderate to significant instability will exist along the boundary too. A few soundings I pulled from the 0z NAM have almost 300 m2/s2 of 0-3km SRH, but several questions still remain on if storms do develop and what storm mode will be predominant. 

 

Saturday's threat is a little more obvious with a more potent shortwave moving through, but the true threat level will probably depend on a lot on Friday night's convection and how well the front recovers. My experiences in Ohio always tell me to assume the warm front won't progress as north as modeled a few days out, and therefore would limit the threat to southeastern Nebraska, southern IA and northern MO

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The 12z 3km NAM shows a rather bullish scenario for Saturday, with a 992mb low cutting through Iowa during the afternoon. The parameter space advertised on the NAM would suggest the potential for the development of a significant MCS across the Midwest by Saturday evening. Storm mode would probably be a bit of an issue for chasers, but one would have to imagine at least a narrow window for discrete supercells early on in the event given the strength of the wind fields aloft and veering with height. (Even low level jet is impressive by early afternoon.)

The Euro is more conservative, but still develops a seasonably strong surface low in the Iowa vicinity. 

Of course, there's the potential as mentioned above that any significant convection early Saturday could have an effect on renewed storm development, especially if a large cold pool is leftover. 

Either way, Saturday definitely has my attention. 

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9 minutes ago, cmasty1978 said:

i was on the fence about going out but i think i'll try near SLN and hope to catch a decent sup prior to congealment...

Gonna congeal fast, and I wouldn't want to be in the way of that bow when it first starts to form and still has transient supercell structures within it (i.e, still capable of producing very large hail... possibly baseball sized). The SPC weenie in me wonders if we'll manage to get a PDS SVR watch out of this, seems like a good possibility imo. 

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Just now, jojo762 said:

Gonna congeal fast, and I wouldn't want to be in the way of that bow when it first starts to form and still has transient supercell structures within it (i.e, still capable of producing very large hail... possibly baseball sized). The SPC weenie in me wonders if we'll manage to get a PDS SVR watch out of this, seems like a good possibility imo. 

thanks jojo, i promise to be safe :ph34r:

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In addition to the moderate risk issued today, SPC has issued an enhanced risk tomorrow for far E Nebraska and northern MO, as well as a good portion of southern Iowa. All the CAMs fire something tomorrow afternoon, although timing/location issues still exist. Wouldn't be surprised if the ENH gets shifted a touch north along the best moisture gradient in IA.

How tomorrow plays out will be crucial for Saturday's potential. If storms can clear the area fairly quickly overnight Friday night/Saturday morning, we should see a pretty quick recovery and some significant severe weather. Also worth watching what happens with the activity in the Dakotas overnight. Either way should be a very busy next 3 days across the region.

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BULLETIN - EAS ACTIVATION REQUESTED
Tornado Warning
National Weather Service Dodge City KS
152 PM CDT THU JUN 15 2017

The National Weather Service in Dodge City has issued a

* Tornado Warning for...
  East central Trego County in west central Kansas...
  Southwestern Ellis County in central Kansas...

* Until 230 PM CDT
    
* At 151 PM CDT, a severe thunderstorm capable of producing a tornado
  was located near Riga, or 13 miles southeast of Wakeeney, moving
  east at 10 mph.

  HAZARD...Tornado and tennis ball size hail. 

  SOURCE...Radar indicated rotation. 

  IMPACT...Flying debris will be dangerous to those caught without 
           shelter. Mobile homes will be damaged or destroyed. 
           Damage to roofs, windows, and vehicles will occur.  Tree 
           damage is likely. 

* This dangerous storm will be near...
  Riga around 205 PM CDT. 
  Ellis around 225 PM CDT. 
  Yocemento around 230 PM CDT. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TAKE COVER NOW! Move to a basement or an interior room on the lowest
floor of a sturdy building. Avoid windows. If you are outdoors, in a
mobile home, or in a vehicle, move to the closest substantial shelter
and protect yourself from flying debris.

&&

LAT...LON 3888 9973 3902 9974 3900 9939 3874 9947
TIME...MOT...LOC 1851Z 283DEG 9KT 3892 9967 

TORNADO...RADAR INDICATED
HAIL...2.50IN
 

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Ouch...

The National Weather Service in Dodge City has issued a

* Tornado Warning for...
  East central Trego County in west central Kansas...
  Southwestern Ellis County in central Kansas...

* Until 245 PM CDT
    
* At 158 PM CDT, a severe thunderstorm capable of producing a tornado
  was located 3 miles south of Riga, or 15 miles southeast of
  Wakeeney, moving east at 15 mph.

  HAZARD...Tornado and softball size hail. 

  SOURCE...Radar indicated rotation. 

  IMPACT...Flying debris will be dangerous to those caught without 
           shelter. Mobile homes will be damaged or destroyed. 
           Damage to roofs, windows, and vehicles will occur.  Tree 
           damage is likely. 

* This dangerous storm will be near...
  Ellis around 210 PM CDT. 
  Yocemento around 245 PM CDT. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TAKE COVER NOW! Move to a basement or an interior room on the lowest
floor of a sturdy building. Avoid windows. If you are outdoors, in a
mobile home, or in a vehicle, move to the closest substantial shelter
and protect yourself from flying debris.

&&

LAT...LON 3888 9973 3895 9967 3893 9941 3874 9947
TIME...MOT...LOC 1858Z 284DEG 13KT 3891 9963 

TORNADO...RADAR INDICATED
HAIL...4.00IN
 

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SPC mentioned the potential consideration for a PDS severe watch as significant MCS evolution is possible. The downstream environment across central to southeast Kansas would certainly support it: 

IMG_2798.thumb.JPG.b0738ae02b6faba1d94d0e0225328412.JPG

Even the initial supercell near Hays was very outflow dominant. I'm a few miles to the south of the leading edge of precip and it's clear that cool, outflow winds are occurring. The temperature has dropped at least 15F here in the last hour.

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Complex convective evolution expected once again this afternoon/tonight and during the second half of Saturday. The latter will be even further modulated by what happens over the next 12-24 hours. 

Today looks like mixed convective modes in two regimes, perhaps most focused in eastern Nebraska immediately ahead of a surface low, and farther northeast along a surface boundary into the upper Midwest. The greatest potential for a few initial supercells will probably be over Nebraska, although I wouldn't rule out something in northern Kansas as well. The potential exists for a modest MCS tonight, as storms interact, moving into northern Missouri  

Saturday looks more messy than some earlier progs, at least with respect to the orientation of a surface boundary and more of an area of low pressure, as opposed to a strong surface cyclone. Still, I'd expect mixed modes with at least some brief supercell potential. The bigger story will probably be the threat of a significant MCS evolving Saturday night across parts of the Midwest and vicinity. Model progs have been wavering (with both placement of surface features and intensity of the low) and better details may hold off until we see how convective trends look tonight. 

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Been an interesting week here in Council Bluffs. I'm waiting on the NWS to review my video and pictures to confirm it but I'm fairly certain a small weak landspout/tornado occurred near/in my grandparents yard on Monday afternoon. I still do not know where the winds from the west came from on velocity because it went from nothing to strong straight line winds (only knew because brother mentioned winds being really strong in Omaha but radar showed nothing impressive until I looked at velocity and then stepped outside) but it never developed into a storm; the closest storm was about 30-40 south/southeast of me and moving away. My guess is the unexplained winds from the west and the winds that popped up in the last frame coming south to north collided over town and possibly either the Missouri River and/or Lake Manawa enhanced some kind of rotation.

It took down a street sign, nearly pulled a tree over (winds were blowing very strong towards Omaha west of me at the very beginning, like it was being pulled into something, the exact opposite of what velocity showed coming) some fence boards had their tops popped outward, a tree branch knocked into a transformer and another branch in the road on the other side of the block. Very small and narrow path of damage but watching the uncompressed video multiple times, I've paid close attention to the direction the ground debris goes in the initial moments of chaos and that's when I decided to have the NWS review it.

Velocity loop 8 minutes prior

 giphy.gif 

Reflectivity loop 

giphy.gif

Full video. First minute is the chaos, the rest was going out to check for other damage. 

 

Last night was a storm with near constant lightning, made for some great video and watching the backside of it. Today should be interesting if things pan out.

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TOG with this storm now

BULLETIN - EAS ACTIVATION REQUESTED  
TORNADO WARNING  
NATIONAL WEATHER SERVICE OMAHA/VALLEY NEBRASKA  
444 PM CDT FRI JUN 16 2017  
  
THE NATIONAL WEATHER SERVICE IN OMAHA HAS ISSUED A  
  
* TORNADO WARNING FOR...  
  NORTHEASTERN MADISON COUNTY IN NORTHEASTERN NEBRASKA...  
  SOUTHERN PIERCE COUNTY IN NORTHEASTERN NEBRASKA...  
  
* UNTIL 515 PM CDT  
      
* AT 444 PM CDT, A SEVERE THUNDERSTORM CAPABLE OF PRODUCING A TORNADO  
  WAS LOCATED 8 MILES WEST OF PIERCE, OR 16 MILES NORTHWEST OF  
  NORFOLK, MOVING SOUTHEAST AT 30 MPH.  
  
  HAZARD...TORNADO AND QUARTER SIZE HAIL.   

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Great shot! I was wondering what janetjanet's source was...new warning still says radar indicated.

*Storm to the NE is also acquiring fairly significant rotation, headed in the general direction of a town that is rather well-known in storm chasing circles, but I'm sure they'd rather not repeat that event.

*2nd edit: TOR warned just as I hit post!

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