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Feb. 23-25th Winter Storm Potential


Chicago Storm

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Eh, I personally dont think snowcover alters storm tracks per say, but I give that possiblity a lot more credence then the "snow wont stick during the daytime" that will start popping up in earnest on the board.

This is definitely not true. Try forecasting in spring after big storms where the models fail with initialization of the snow pack. It is pretty tough.

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This is definitely not true. Try forecasting in spring after big storms where the models fail with initialization of the snow pack. It is pretty tough.

this from the morning AFD from DVN.

A

GOOD BET THAT THE SYSTEM MAY PULL UP FURTHER NORTHWEST THAN EVEN THE

ECMWF SOLUTION SUGGESTS...AS MODELS GET A BETTER HANDLE ON LLVL

THERMAL FIELDS AND SNOW COVER ACRS THE UPPER MIDWEST.

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this from the morning AFD from DVN.

A

GOOD BET THAT THE SYSTEM MAY PULL UP FURTHER NORTHWEST THAN EVEN THE

ECMWF SOLUTION SUGGESTS...AS MODELS GET A BETTER HANDLE ON LLVL

THERMAL FIELDS AND SNOW COVER ACRS THE UPPER MIDWEST.

Well, considering there's also snow across the lower Great Lakes and Ohio Valley, I don't see how this comment makes any sense.

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So there is credence to the theory that Winter Storms will sometimes follow the snow pack?

Atmospheric dynamics is a long and complicated discussion--but it can be shown through various equations that the upper level jet can be related to the horizontal thermal gradient in the vertical. The greater the horizontal thermal gradient through a vertical layer--the stronger the wind aloft.

post-999-0-74713500-1298346165.png

The snow pack, especially in spring, can reinforce where the greatest thermal gradient is in the low levels and that can even feedback into the vertical through boundary layer mechanisms of diffusion, vertical convection, horizontal advection, etc. So yeah--the snowpack is important--and it can lead to weaker storms and/or upper tropospheric wave disturbances embedded in the jet level flow "propagating" along the low level thermal gradient aka baroclinic zone. Eventually larger rossby waves associated with the various teleconnection/large scale planetary circulation patterns will drive large scale flows through a deep enough layer of the atmosphere that can develop much larger storms that develop their own baroclinic zones. In other words--they not only develop off existing baroclinic zones--they make their own. So to a degree--a snowpack can result in storms continuously propagating along the low level baro zone where the upper jet resides--but like anything in weather--is only one small piece of the puzzle.

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Well, considering there's also snow across the lower Great Lakes and Ohio Valley, I don't see how this comment makes any sense.

After tonight there is a bunch across Northern Indiana and Ohio, you are right, but not much over Northern Illinois, it would probably be influenced by the snowpack over Minnesota and Wisconsin before Indiana and Ohio, given geography. Just a thought.

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Atmospheric dynamics is a long and complicated discussion--but it can be shown through various equations that the upper level jet can be related to the horizontal thermal gradient in the vertical.

post-999-0-74713500-1298346165.png

The snow pack, especially in spring, can reinforce where the greatest thermal gradient is in the low levels and that can even feedback into the vertical through boundary layer mechanisms of diffusion, vertical convection, horizontal advection, etc. So yeah--the snowpack is important--and it can lead to weaker storms and/or upper tropospheric wave disturbances embedded in the jet level flow "propagating" along the low level thermal gradient aka baroclinic zone. Eventually larger rossby waves associated with the various teleconnection/large scale planetary circulation patterns will drive large scale flows through a deep enough layer of the atmosphere that can develop much larger storms that develop their own baroclinic zones. In other words--they not only develop off existing baroclinic zones--they make their own. So to a degree--a snowpack can result in storms continuously propagating along the low level baro zone where the upper jet resides.

Looks like Im gona have to bust out my meteo books.

Baro..Thanks for the good write up! Your a wealth of knowledge to us home gamers.

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Yes but both of those models are on the northern end of the envelope, no model right now is showing a track close to that.

Considering the problems well documented on here with the southern group of solutions, I'm trusting the northern solutions a lot more right now. I think it was Detroit's AFD that said it is a pretty likely bet this tracks through the Ohio Valley, which would be solid for the aforementioned areas.

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Considering the problems well documented on here with the southern group of solutions, I'm trusting the northern solutions a lot more right now. I think it was Detroit's AFD that said it is a pretty likely bet this tracks through the Ohio Valley, which would be solid for the aforementioned areas.

Yes, a track through the northern side of Ohio valley doesn't yield a CR-RFD-MKE hit though, not at all.

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Yes, a track through the northern side of Ohio valley doesn't yield a CR-RFD-MKE hit though, not at all.

I'm not saying it WILL happen this way, but you're the one discounting the possibility of it occurring. Our best track would probably be something like just north of St. Louis to Champaign to Fort Wayne, which is through the central or northern Ohio Valley region. Then again, I've always considered Illinois, Indiana and Ohio as encompassing the Ohio Valley, but I understand not everyone would agree.

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I'm not saying it WILL happen this way, but you're the one discounting the possibility of it occurring. Our best track would probably be something like just north of St. Louis to Champaign to Fort Wayne, which is through the central or northern Ohio Valley region. Then again, I've always considered Illinois, Indiana and Ohio as encompassing the Ohio Valley, but I understand not everyone would agree.

The southern parts of those states are, STL to Champaign to FWA is much further north than those areas. Either way I am not expecting this to track that far north.

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As said in the other thread about the storm exiting tonight. It has a bit to do with entry point in the plains and then blocking and ofcourse the snow cover. The AO/NAO is/has moved back up and thus a lessor chance of this being suppressed/staying south. Which leaves us with the entry point into the plains, snowcover and strength of storm. Chances are very high this one does not cut nearly as far nw as the one just leaving did ( should enter the Plains via Texas ) but it will end up farther north because of the lack of blocking and thus don't expect for it to come up to i70 ( for example ) and get turned east. How hard it cuts ( turns north once it gets into Texas ) will depend on how fast it develops/strengthens. Rarely ( always exceptions ) do you see a Texas low track over or west of here unless it was a bombing low/closed off. Now if it was to come out and track along the KS/OK line the chances go up for a cut over or west of here towards the Lake. With the trough coming into the west/rockies and then energy having to take the southern route near MX the system should emerge into the Plains in Texas. Basically it is a question of how strong will this thing get and how quick. I say that because it really should not feel the snowcover effects till reaching IL/IN etc. Best way ( not saying much ) for this to stay farther se and track across say TN/KY would be for it to stay very weak and that will still be hard to do.

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As said in the other thread about the storm exiting tonight. It has a bit to do with entry point in the plains and then blocking and ofcourse the snow cover. The AO/NAO is/has moved back up and thus a lessor chance of this being suppressed/staying south. Which leaves us with the entry point into the plains, snowcover and strength of storm. Chances are very high this one does not cut nearly as far nw as the one just leaving did ( should enter the Plains via Texas ) but it will end up farther north because of the lack of blocking and thus don't expect for it to come up to i70 ( for example ) and get turned east. How hard it cuts ( turns north once it gets into Texas ) will depend on how fast it develops/strengthens. Rarely ( always exceptions ) do you see a Texas low track over or west of here unless it was a bombing low/closed off. Now if it was to come out and track along the KS/OK line the chances go up for a cut over or west of here towards the Lake. With the trough coming into the west/rockies and then energy having to take the southern route near MX the system should emerge into the Plains in Texas. Basically it is a question of how strong will this thing get and how quick. I say that because it really should not feel the snowcover effects till reaching IL/IN etc. Best way ( not saying much ) for this to stay farther se and track across say TN/KY would be for it to stay very weak and that will still be hard to do.

Yeah as I mentioned earlier, to see this thing cut hard left we would need it to take on a negative tilt very early and be very vigorous also.

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The southern parts of those states are, STL to Champaign to FWA is much further north than those areas. Either way I am not expecting this to track that far north.

OK, thanks for the clarification. I always thought the Ohio Valley was the area between the Great Lakes and the Ohio River, which would include prime territory for a winter storm if a storm tracked through the northern sections of that region. The Ukie, Euro, and NAM all take a track through Central Missouri, Central or Southern Illinois, and Central Indiana I believe. It's them vs. the GFS and GGEM overall.

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