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February 21-23 Major Winter Storm


Hoosier
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18 minutes ago, RCNYILWX said:

I'd recommend grabbing the winter sounding from COD (just have to select winter and generate new sounding) or go to Pivotal Weather which automatically will give a winter sounding.

On the bottom right of the winter soundings, you'll see layer energy information, which is the Bourgoin method to determine precipitation types. It's analogous to CAPE and DCAPE, positive energy aloft and negative energy low level. The precip. type tab in BUFKIT uses the Bourgoin method.

Any positive energy of 25+ J/kg represents full melting, while sleet probabilities increase at -75 J/kg and below. Even with high positive energies (near or above 100 J/kg), negative energies of -100 J/kg or lower tend to allow for sleet to at least mix in and the higher magnitude negative energies can overcome high positive energies to result in primarily sleet. The preferred profile to use is the wet bulb vs. solely temperature based profile.

Two examples of this from the 12z ECMWF below, first from interior far northeast IL and the other from near the state line on WI side of the border. 6c0e99783a4bf5632e4b411813570651.jpg7f332c395a399bbb66b2c2242025b6dd.jpg

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Thanks!  Kinda embarrassed to say that I didn't know COD had that winter selection lol.  I was basically eyeballing the positive/negative energies on the soundings, but it's nice to have numbers.

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1 hour ago, RCNYILWX said:

I'd recommend grabbing the winter sounding from COD (just have to select winter and generate new sounding) or go to Pivotal Weather which automatically will give a winter sounding.

On the bottom right of the winter soundings, you'll see layer energy information, which is the Bourgoin method to determine precipitation types. It's analogous to CAPE and DCAPE, positive energy aloft and negative energy low level. The precip. type tab in BUFKIT uses the Bourgoin method.

Any positive energy of 25+ J/kg represents full melting, while sleet probabilities increase at -75 J/kg and below. Even with high positive energies (near or above 100 J/kg), negative energies of -100 J/kg or lower tend to allow for sleet to at least mix in and the higher magnitude negative energies can overcome high positive energies to result in primarily sleet. The preferred profile to use is the wet bulb vs. solely temperature based profile.

Two examples of this from the 12z ECMWF below, first from interior far northeast IL and the other from near the state line on WI side of the border. 6c0e99783a4bf5632e4b411813570651.jpg7f332c395a399bbb66b2c2242025b6dd.jpg

Sent from my SM-G998U using Tapatalk
 

Is it even possible to get a low-level hodo like that in a warm sector with CAPE? Where the wind goes from ENE at the surface to SW at 1KM? And those SRH numbers...

:twister::twister::twister:

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1 hour ago, CheeselandSkies said:

Is it even possible to get a low-level hodo like that in a warm sector with CAPE? Where the wind goes from ENE at the surface to SW at 1KM? And those SRH numbers...

:twister::twister::twister:

It happens commonly where there is terrain influenced flow, like Colorado.  Denver area gets some wild looking hodos.  It seems more difficult outside of the plains though.

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37 minutes ago, Hoosier said:

The GFS solution would be pretty wild, especially in parts of MI.  Lots of ice, which would be followed by quickly melting/falling ice courtesy of very strong winds as the trailing surface low of decent depth passes nw.

It's kind of a complicated situation with the lead low having most of the moisture.  On the GFS there's a definite break between the initial surge of overrunning precip and the main low.  I don't know if that will help much though.  The warm sector looks mostly dry, but there could be one of those narrow lines of convective showers right by the cold/occluded front that pulls some strong gusts down to the surface.

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There was one ice storm I remember from the vaunted winter of 2013-'14 where I came out to leave for work one night (3AM start) and found my car completely encased in about 1/4" of solid ice. That was a fun nearly half hour of chipping and scraping.

Still waiting to top that, now that I live at an apartment complex with indoor parking. ;)

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3 hours ago, frostfern said:

It's kind of a complicated situation with the lead low having most of the moisture.  On the GFS there's a definite break between the initial surge of overrunning precip and the main low.  I don't know if that will help much though.  The warm sector looks mostly dry, but there could be one of those narrow lines of convective showers right by the cold/occluded front that pulls some strong gusts down to the surface.

Also have some uncertainty on the exact track of the second low.  The first wave is pretty well agreed upon to go through central IL/IN and into Ohio, staying south of Michigan.  ECMWF and Canadian aren't as far north as the GFS is with the trailing low, and the best winds with that should occur near/south of its track.

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50 minutes ago, Hoosier said:

Also have some uncertainty on the exact track of the second low.  The first wave is pretty well agreed upon to go through central IL/IN and into Ohio, staying south of Michigan.  ECMWF and Canadian aren't as far north as the GFS is with the trailing low, and the best winds with that should occur near/south of its track.

The strength of the northern stream system is kind of in question too.  There's a lot of baroclinicity, but the wave itself is not very compact.  The lead southern stream low pulls a lot of moisture north, but it doesn't really deepen the broad upper-level system ejecting from the SW.  The phasing isn't very constructive.

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42 minutes ago, Toro99 said:

Omg, the overnight GRR write up is worth a read

That was quite the read. Interesting language they are using. I work for a power company in SE mich and how some of our power lines look and some of the 60 year old poles we have. The area would be in for some deep trouble if current forecasts hold

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1 hour ago, sbnwx85 said:

GFS is a touch south at 12z. Canadian a touch north. Some relatively minor run-to-run variability but overall each model has been really consistent since Friday. 

Was surprised to see the GFS even trying to paint a little ice here.  Seems like an outlier at this point.

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This mid-level jet is a freakshow.  500 mb winds of 130-140 kts on Thursday.  Hardly ever see that in this region, with the most notorious occurrence probably being on 4/11/1965.  To be clear, I'm not predicting an outbreak like that or anything close to it.  Only comparing the wind speeds.  :lol:

Thursday is sort of an atypical high wind setup with a relatively modest surface low (maybe not much below 1000 mb) and lack of a stronger surface high.  So much wind aloft though and the pressure gradient that we do have is packed in pretty nicely.

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