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12/3-12/6 MW/GL snow event?


Thundersnow12

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Lets see if I still got the magical touch...

from the MKX office

BACKING UPPER LEVEL WINDS TO RESULT IN TIGHTENING LOW LEVEL

BAROCLINIC ZONE ACROSS NORTHERN PLAINS INTO SRN WI AND NRN IL ON FRI

AND SAT. OVER THE LAST SEVERAL DAYS...ALL EXTENDED GUIDANCE HAS

BEEN SHOWING SHORT WAVE TROUGH MOVING THROUGH THERMAL RIBBON...

HOWEVER STRENGTH AND TIMING HAVE BEEN VERY INCONSISTENT. HI RES

ECMWF HAS BEEN WAFFLING LAST DAY OR SO...AND HAS RETURNED TO SNOWIER

SOLUTION...WITH 0.25 TO 0.50 INCH LIQUID EQUIVALENT OVER SRN WI FRI

NGT AND SAT. LATEST GEM HAS ALSO TRENDED TOWARD THIS WETTER

SOLUTION...BUT CARRIES SFC LOW FARTHER SOUTH...WHILE GFS SLIGHTLY

DRIER BUT WARMER. FOR NOW WL CARRY CHC POPS FOR -SN DURING THIS

PERIOD BUT BEARS WATCHING. WL RETURN WORDING TO HWO FOR POTENTIAL

HEADLINE EVENT.

GEM

ECMWF

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Per usual a lot of the area NWS's are being very conservative and broadbrushing the system with very light mention so far out. The system actually started on the GFS a good 5 days ago before it totally lost it, but the Euro and GEM have been relatively consistent. We shall see what happens. I will admit, for the first time of the season, i am checking every model run and counting the days. Welcome winter 2010-2011! :thumbsup:

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Per usual a lot of the area NWS's are being very conservative and broadbrushing the system with very light mention so far out. The system actually started on the GFS a good 5 days ago before it totally lost it, but the Euro and GEM have been relatively consistent. We shall see what happens. I will admit, for the first time of the season, i am checking every model run and counting the days. Welcome winter 2010-2011! :thumbsup:

In this case I am ok with that. This one is a tough one because it is a partial phase event over the Pacific: http://www.atmos.was...+2010112912///3

Models are going to be doing the flippity-flop for the next couple days most likely.

Models, therefore, have a tough time in simulating how far south the wave develops and the amount of moisture it will have. Moreover models are progging this to be a surface frontal wave event in some aspects so there is potential for some pretty sharp snow gradients associated with frontal banding. It would be a bad idea for them to start pin pointing things at this point.

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Yeah I agree. Even though we all know the relative risk and potential with this thing, the NWS and broadcast media are smart not to get too cute with it yet. Even though the GEM, Euro and others have been relatively consistent with it, it's still a ways out there. Anyway, I can't wait to see the new GEM and Euro.

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The new GFS keeps it further north than the earlier GEM and Euro runs, much like the 12z GFS. It is much wetter than the 12z though, pumping out 0.3-0.6" of QPF. The evolution of the storm is slower than the Euro and GEM by about 12hrs.

It's all going to come down to where the baroclinic boundary parks itself.

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The new GFS keeps it further north than the earlier GEM and Euro runs, much like the 12z GFS. It is much wetter than the 12z though, pumping out 0.3-0.6" of QPF. The evolution of the storm is slower than the Euro and GEM by about 12hrs.

It's all going to come down to where the baroclinic boundary parks itself.

Mostly right, and the amount of upper level wave phasing as well. The last supposed clipper null event that was hyped a lot a couple weeks ago for Indiana/IL/Iowa was a good example of a baroclinic boundary being significantly farther displaced than what models originally suggested because the OV storm ended up being considerably more intense than models were predicting. The baroclinic zone was shunted well to the south and the associated clipper took a huge dive south and missed everyone. A good learning example in model fail with low amplitude waves when the associated waves are still well over the Pacific and outside of the upper air raob network.

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Mostly right, and the amount of upper level wave phasing as well. The last supposed clipper event that was hyped a lot a couple weeks ago for Indiana/IL/Iowa was a good example of a baroclinic boundary being significantly farther displaced than what models originally suggested because the OV storm ended up being considerably more intense than models were predicting. The baroclinic zone was shunted well to the south and the associated clipper took a huge dive south and missed everyone. A good learning example in model fail with low amplitude waves when the associated waves are still well over the Pacific and outside of the upper air raob network.

Good point. I remember that quite well. The models handled that system very poorly right up to about 48hrs out.

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Well we do know that there's a bias for models to phase energy, and especially includes the GFS, which has been notorious for doing this in the past. I'm inclined for this to be 2 separate waves. We do know that there's a good chance there will be an upper high (subtropical) sitting over Mexico, so this will generally put a restriction on how far south the system can track. This was not the case with the previous clipper system, however Baro makes a good point in mentioning that this thing is still well outside the reach of our RAOB network, and still vulnerable to drastic adjustments.

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One thing that should help ground temperatures is the fact end of this week is supposed to be below freezing all day.

At least here that is.

Wed: High: 27 Low: 16

Thu: High: 27 Low: 17

Fri: High: 28 Low: 20

In Chicago:

Wed: High: 29 Low: 19

Thu: High: 31 Low: 20

Fri: High: 31 Low: 23

So it looks to be below freezing in most areas.

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If this thing does pan out, I will be interested to see what the thermal profiles look like. Anyone know the current ground temps around here?

Not sure, need to hook my ground temp sensor back up.

When we were cold a few days ago it was enough to fully freeze puddles and keep the heavy frost on the ground through the day with full sun...so i'm sure as long as air temps are around/below freezing snow would stick fairly well.

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Well we do know that there's a bias for models to phase energy, and especially includes the GFS, which has been notorious for doing this in the past. I'm inclined for this to be 2 separate waves. We do know that there's a good chance there will be an upper high (subtropical) sitting over Mexico, so this will generally put a restriction on how far south the system can track. This was not the case with the previous clipper system, however Baro makes a good point in mentioning that this thing is still well outside the reach of our RAOB network, and still vulnerable to drastic adjustments.

Yeah I agree, GFS is the most notorious with phasing. That said, I definitely won't deny the potential, especially if something along the lines of the 12Z Euro and to a degree the CMC were to develop. Cold side frontal banding and prolonged heavy snow with no worry of deep cyclogenesis and warm sector crap/dry slots...these things can be fun to watch. GFS is by far the least exciting and for now I am not considering it much since it has been all over the map with this system.

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Yeah I agree, GFS is the most notorious with phasing. That said, I definitely won't deny the potential, especially if something along the lines of the 12Z Euro and to a degree the CMC were to develop. Cold side frontal banding and prolonged heavy snow with no worry of deep cyclogenesis and warm sector crap/dry slots...these things can be fun to watch. GFS is by far the least exciting and for now I am not considering it much since it has been all over the map with this system.

And then we'll get to see what the good ole NAM shows in the next few days lol I love events like these. nothing worse then being in the dry slot.

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