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October 24-27, 2022 | Winter Storm Northern Plains and Severe Threat Southern Plains


StLweatherjunkie

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  • Meteorologist
8 hours ago, ClicheVortex2014 said:

Seems like the models are honing in on a threat in Kansas rather than E NE/W IA.

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Area average sounding for south-central KS... that's nasty. There is a slight inversion but, considering this is an area average sounding, there's gonna be some spots where there's sufficiently weak capping. 

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Yup was talking about this at work yesterday. Looks like it may be one of those conditional days here.

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25 minutes ago, CentralLA_Wx said:

Some Dixie Alley potential next Tues? 

image.png.865933b55955bd1a6510c113556e3faf.png

Yes, per SPC Discussion. 

A southern-stream shortwave trough is forecast to progress from the
   southern Plains northeastward across the Mid-South and into the OH
   Valley on D4/Tuesday. An associated surface low will move
   northeastward just ahead of this shortwave, with an attendant cold
   front sweeping eastward as well. Moderate low-level moisture will
   likely be in place across the Mid-South and Lower MS Valley ahead of
   this front, supporting the development of thunderstorms along the
   front as it moves eastward/northeastward. Current expectation is
   that poor lapse rates and limited heating will temper buoyancy.
   However, given the strong forcing for ascent and intense kinematic
   fields, only modest buoyancy will be needed for a severe
   thunderstorms. As a result, a 15% area was delineated from southwest
   TN across much of MS for D4/Tuesday.

Either way, welcome here! You're likely the very first from Dixie Alley to join here! 😄 

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  • Meteorologist

I'm skeptical about Sunday because of capping, but Monday and Tuesday look really impressive. Sunday has almost always had capping concerns, but those concerns evaporate afterward.

Although they come from the same longwave trough, Sunday is a different event from Monday and Tuesday. 

 

floop-gfs-2022102212.500wh.conus.gif

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  • Meteorologist

Getting very concerned about Tuesday. Looks like a pretty classic Dixie Alley setup. 

image.png.3446f4370c94d7b69675cd5799c4d61f.png

image.png.e9772f17871d48a30813694361b721bd.png

 

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I don't see a reason to doubt the moisture quality because of reasons I shared on the previous page, but GFS has a pretty narrow warm sector. That wouldn't mean anything for frontal storms, but would discourage severe warm sector activity. 

The difference in warm sector width is due to disagreements about how quickly the Southeast recovers from cold air damming. 

image.thumb.png.334eafc5f38c574a8a240906fc35d73a.png

Edited by ClicheVortex2014
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11 hours ago, Ingyball said:

Yup was talking about this at work yesterday. Looks like it may be one of those conditional days here.

Most models have pretty low MUCAPE for the severe threat tomorrow. The convection-allowing models are not showing much. I think it just one of those days with a relatively common problem for fall, lack of instability. The HRRR does have a bit more activity for Kansas.

Here is a map of I am talking about. The MUCAPE values are only 250-500 J/kg with a couple possible areas of activity. I would suppose that areas of convection could be in a few areas, but obviously the system is fighting with low CAPE.

 

hrrr_2022-10-22-18Z_033_45.5_250.333_32.111_274.533_CAPE_Most-Unstable_Simulated_Reflectivity_Reflectivity.png

Edited by Chinook
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2 hours ago, Chinook said:

Most models have pretty low MUCAPE for the severe threat tomorrow. The convection-allowing models are not showing much. I think it just one of those days with a relatively common problem for fall, lack of instability. The HRRR does have a bit more activity for Kansas.

Here is a map of I am talking about. The MUCAPE values are only 250-500 J/kg with a couple possible areas of activity. I would suppose that areas of convection could be in a few areas, but obviously the system is fighting with low CAPE.

 

hrrr_2022-10-22-18Z_033_45.5_250.333_32.111_274.533_CAPE_Most-Unstable_Simulated_Reflectivity_Reflectivity.png

CAPE almost doesn't matter in this kind of setup. We're talking about 55-65kt winds at 850mb. It doesn't take much convection to mix those down. However, I am skeptical we actually see storms, I think the cap likely holds. 

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 HRRR is showing one of those squalls that start early in the day and continue throughout. Seems pretty reasonable to think there won't be much, if any, strong warm sector convection given the trough is still positively tilted... though it gets close to neutral tilt by 0z. 

Tuesday should be a different story as the trough should be negatively tilted by then. 

floop-hrrr-2022102300.refcmp.us_sc.gif.d5a47cf109eecd31b36702b4c5d3d1a5.gif

 

Both images are for 15z Monday. The positive tilt axis is all the way in Arizona while the frontal storms are ongoing in central Texas. Only meaningful forcing there is due to the cold front.

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9 hours later, the original squall significantly weakens and slows. The trough is now roughly neutrally tilted over east NM/west TX. Now you see new development BEHIND the cold front... that's due to the trough axis/jet streak swinging around and adding a new area of forcing. Divergence aloft associated with the jet streak also creates a new area of low pressure. It'll take some time for the airmass behind the squall to recover, but it will. Now you have a low pressure located MUCH closer to the trough. 

Unfortunately, it's looking like the trough will begin to take a negative tilt in the nighttime. This'll increase shear, forcing, and moisture. That should cause the squall to strengthen throughout the night. It should be a full-on negative tilt by daytime, which raises the concern for warm sector convection.

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Edited by ClicheVortex2014
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14 minutes ago, ClicheVortex2014 said:

So much going on here. Dust in Kansas. Gravity waves in New Mexico.

Those in Ohio/Indiana... why is satellite showing so much brown? Only thing I can think of is crops.

CODNEXLAB-GOES-East-regional-midwest-truecolor-19_51Z-20221023_map_-24-1n-5-100.gif

I think it's showing how parched it is, the Mississippi River is at an all-time low

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31 minutes ago, ClicheVortex2014 said:

So much going on here. Dust in Kansas. Gravity waves in New Mexico.

Those in Ohio/Indiana... why is satellite showing so much brown? Only thing I can think of is crops.

CODNEXLAB-GOES-East-regional-midwest-truecolor-19_51Z-20221023_map_-24-1n-5-100.gif

Quite a few wildfires popping up in KS and NE as well 

ezgif-2-cdbe0fa594.gif.fc7b1d611f3282f87a6f673eb1670dbc.gif

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3 hours ago, ClicheVortex2014 said:

So much going on here. Dust in Kansas. Gravity waves in New Mexico.

Those in Ohio/Indiana... why is satellite showing so much brown? Only thing I can think of is crops.

CODNEXLAB-GOES-East-regional-midwest-truecolor-19_51Z-20221023_map_-24-1n-5-100.gif

You can see the dirt or smoke on the move in Kansas on the loop.

There were two confimed tornadoes in Nebraska, at 5:53PM and 6:04PM

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