12/20-12/21 Moderate/Intense Clipper Event?

[Harry]

What does euro show for qpf across iowa?

.10 to .25 from near/just north of i80 ( Less along and south of i80 ) and .25+ for the counties along the MN border.

[Harry]

The EURO/UK/NAM look almost identical with the S/W trough and all feature a very sharp S/W over northern MN with the exception of some speed differences. Right now it looks like a rather quick hitting event.

What a complete waste of energy if that happens.

Oh well. Time to start a countdown to the demise of this rotten pattern. I'll take a coast to coast torch if that's the price for getting rid of this. The sooner the better.

[TimChgo9]

I am still not biting.

Based on a quick analysis, it can go a couple of ways:

Low weakens considerably before reaching this area, resulting in a dusting at best.

Low pulls way north, and while we have plenty of cold air we still wind up with a sloppy mixing, or semi-mixing event

Track stays to our south and we have anywhere from 3" to 6" of snow. (2 to 4 probably more likely)

I am not going to quote odds on any one of these scenarios. Too many factors in play to settle on something more or less definite. I think I will wait a couple more runs before I figure on anything. Given the time of year, some sort of mixing would not be out of the question for the NE IL/NW IN/SE WI area. The last storm was shown to be too far south, then it was shown going through C IL, and then at 66 hours, the GFS showed the low over NE IL/SE WI. Eventually, there was some southerly correction, but we still wound up with a mix, and then as usual, little to nothing on the back end. With one of the models showing this current event down near Kentucky at one point, I would have to imagine in the next 24 hours or so, there will be at least a 400 mile correction on the track. I base this prediciton on the time of year, and the fact that we generally don't get our big snows here in December, January and February are the more likely months for that.

I will probably wait until later tonight, or early tomorrow to see what the models have to say, regarding snow for this area.

As far as the Christmas Eve "storm" goes... let's get this first one out of the way....

[Hoosier]

I am still not biting.

Based on a quick analysis, it can go a couple of ways:

Low weakens considerably before reaching this area, resulting in a dusting at best.

Low pulls way north, and while we have plenty of cold air we still wind up with a sloppy mixing, or semi-mixing event

Track stays to our south and we have anywhere from 3" to 6" of snow. (2 to 4 probably more likely)

I am not going to quote odds on any one of these scenarios. Too many factors in play to settle on something more or less definite. I think I will wait a couple more runs before I figure on anything. Given the time of year, some sort of mixing would not be out of the question for the NE IL/NW IN/SE WI area. The last storm was shown to be too far south, then it was shown going through C IL, and then at 66 hours, the GFS showed the low over NE IL/SE WI. Eventually, there was some southerly correction, but we still wound up with a mix, and then as usual, little to nothing on the back end. With one of the models showing this current event down near Kentucky at one point, I would have to imagine in the next 24 hours or so, there will be at least a 400 mile correction on the track. I base this prediciton on the time of year, and the fact that we generally don't get our big snows here in December, January and February are the more likely months for that.

I will probably wait until later tonight, or early tomorrow to see what the models have to say, regarding snow for this area.

As far as the Christmas Eve "storm" goes... let's get this first one out of the way....

I think the bolded scenario is most likely...that's where the best agreement is right now anyway. Also, not sure we can compare this low to the Minnesota blizzard...the setup was pretty different.

[TimChgo9]

I think the bolded scenario is most likely...that's where the best agreement is right now anyway. Also, not sure we can compare this low to the Minnesota blizzard...the setup was pretty different.

True, two different animals. I agree with the blocking in place, the southerly track is more likely, but, I am not biting until there is something more concrete. I know it's a tad early to worry about precip issues, but the fact that LOT's AFD mentioned the possibility of drizzle, and climbing temps, makes me wonder.

[goknights]

Sref continues to say congrats msp

[baroclinic_instability]

Sref continues to say congrats msp

Even it is going N and slightly more intense with more precip falling westward and into central MN and parts of ND. If these solutions occur, all snow may push out before the game since the dry slot will push in much faster. UK suggests this very scenario.

[Harry]

Sref continues to say congrats msp

Not to shabby..

[baroclinic_instability]

The 18Z NAM is going crap-busters with that S/W and really amplifying things a lot. This would be the most ideal solution for a potential spread the wealth hit.

[Thundersnow12]

18z NAM still north with a good hit from eastern SD to MN out to 54hrs. never know what the NAM is thinking. some storms its good, others its on crack.

60 hrs- really nice NW-SE oriented band of good snow eastern ND to northern IL...hmmm

[Chicago Storm]

The 18Z NAM is going crap-busters with that S/W and really amplifying things a lot. This would be the most ideal solution for a potential spread the wealth hit.

18z NAM still north with a good hit from eastern SD to MN out to 54hrs. never know what the NAM is thinking. some storms its good, others its on crack.

Coming in wetter and more NW/SE oriented.

[baroclinic_instability]

18z NAM still north with a good hit from eastern SD to MN out to 54hrs. never know what the NAM is thinking. some storms its good, others its on crack.

The NAM gets consideration here because of its ability to undergo rapid and intense cyclogenesis. A slightly different scenario here but the same general thoughts apply and the NAM can better model situations where mesoscale effects (NAM has a very strong mesoscale divergent jet circulation) may be prominent as well as times where low static stability must be taken into consideration since cyclogenesis is hastened, both on the synoptic and meso scales, under that scenario. Whenever you have a moist system with strong latent heat release in the low level with a rapidly intensifying shortwave aloft and dynamically driven height falls/cooling, static stability tanks and it can feedback onto the overall development. Static stability plays a prominent role in the omega equation and you can find it in the denominator of all the major forcing terms.

[Thundersnow12]

impressive dumping for some

spreading the wealth..

[baroclinic_instability]

Expanding on that above topic...you can see the NAM has the co-location of the low level warm nose directly underneath the tanking upper level shortwave, and I have a feeling those ridiculous rates are convectively enhanced in western MN and the Dakotas.

[Hoosier]

18z NAM is a good example of how the 540 line isn't the end all be all for precip type. If you get a deep layer of sufficiently cold but not really cold temps it can be misleading. Of course most here know this.

[cyclone77]

Precip type issues getting a little too close for comfort here near the QC, but am digging the wetter solution. Definitely looks really good for the southern half of Minnesota. This continuous pattern is starting to build a hell of a snowpack up there.

[Thundersnow12]

Interesting watching the 850mb warm front with 45-55kts pushing it north and the cold air holding its ground. For a time you get a really nice SSW flow from 850mb but as the system presses on the winds veer and its not that impressive anymore, nice to see my area not budge below -3 at 850

[baroclinic_instability]

Don't have to look any farther than a simple 4/6 panel to see what the NAM is doing with the co-location of those features. This is why the NAM is absolutely tanking this system so fast. The height falls aloft with that shortwave are rapidly destabilizing the mid levels directly above a region of strong low level WAA/diabatic heat release.

This NAM solution is actually quite realistic and is definitely realizing the potential I suggested earlier under this configuration.

[JayPSU]

Then it completely fizzles out by the time it gets here.

[cyclone77]

18z would suggest 7-9" snow potential for much of Minnesota...

[Thundersnow12]

Don't have to look any farther than a simple 4/6 panel to see what the NAM is doing with the co-location of those features. This is why the NAM is absolutely tanking this system so fast. The height falls aloft with that shortwave are rapidly destabilizing the mid levels directly above a region of strong low level WAA/diabatic heat release.

This NAM solution is actually quite realistic and is definitely realizing the potential I suggested earlier under this configuration.

we need to get the s/w further south so MN stops getting all the snow lol

[baroclinic_instability]

Then it completely fizzles out by the time it gets here.

Yeah that is the only problem with these rapidly intensifying systems is they process the baroclinic zone so efficiently and quickly the systems don't take long to reach max intensity before falling apart.

[TimChgo9]

It bothers me that the last few model runs that have been posted, are consistently putting the best precip west of here. It would appear that there is either some serious dry air above far NE IL, or some other situation.

The last snow to come through left us nothing on Wed, and about .5" on Thursday. Off to the west, about 40-50 miles they had 3"-5" and within 25 miles west of me they had about .5" with totals growing larger as one went west, up to 5" in some spots.

Is this the result of the retrograding low across Canada? Is it pumping some drier air down this way? Not sure what to make of the situation. But the maps definitely show better qpf to my west.

[BowMeHunter]

Back to how I more envisioned this event going down.

SNE getting a weenie tease from the NAM, too.

[baroclinic_instability]

It bothers me that the last few model runs that have been posted, are consistently putting the best precip west of here. It would appear that there is either some serious dry air above far NE IL, or some other situation.

The last snow to come through left us nothing on Wed, and about .5" on Thursday. Off to the west, about 40-50 miles they had 3"-5" and within 25 miles west of me they had about .5" with totals growing larger as one went west, up to 5" in some spots.

Is this the result of the retrograding low across Canada? Is it pumping some drier air down this way? Not sure what to make of the situation. But the maps definitely show better qpf to my west.

Read my above post. But basically, if some of these solutions verify, the shortwave aloft will undergo rapid cyclogenesis and will effectively "process" the low level baroclinic zone, essentially occluding early and resulting in a rapid weakening as it heads east. It is a feedback process and a rapidly intensifying solution with low static stability and an active jet combined with an intense S/W aloft all result in a rather rapid but intense period of precipitation followed by a quick drop-off and weakening. This example can be shown with all very intense storms. Sometimes you will hear of "instant occlusion" with very strong storms and really the same general principle applies.

[Harry]

Then it completely fizzles out by the time it gets here.

And here for that matter!

It would be a fitting end to this miserable damn pattern though. And yeah it would be over as it would help kick the miserable block out of the way. bye bye motherfooker. Don't come back..

[Hoosier]

18z NAM tries to change us over to some freezing drizzle at the end but not before some damage is done.

[dilly84]

And here for that matter!

It would be a fitting end to this miserable damn pattern though. And yeah it would be over as it would help kick the miserable block out of the way. bye bye motherfooker. Don't come back..

I agree. No offense to you WI/MN guys but damn, Im sick of seeing you guys get all the snow Same goes to you Cincinnati.

[Harry]

I agree. No offense to you WI/MN guys but damn, Im sick of seeing you guys get all the snow Same goes to you Cincinnati.

I don't mind people getting snow ( Hope all gets buried ) but lets spread it around some.

[Hoosier]

never know what the NAM is thinking. some storms its good, others its on crack.

That's the problem isn't it. This may be a situation it's more likely to have a handle on as baro has explained, but part of me still says "it's the NAM."