Monster Snowstorm? 12/23

I'm hoping we can at least see the western fringe of the cirrus deck, that will be more than exciting :p. Enjoy this storm all you easterners...
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ETA is movin' on west, and getting stronger... Since the event is still a solid 24-36 hours away, and if this westward trend continues, maybe you will get snow after all Joel...
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I'll hold you to that. 8)
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I'm thinking NWS offices will have to make some big changes with the A.M. forecast package regarding the ongoing warnings/watches. DTX menioned that if the 18Z run continued a pronounced westward trend, significant changes to the forecast would need to be made. Nothing is worse than getting a blizzard/snowstorm on one of the busiest travel days, especially when it wasn't predicted until 24 hours or less in advance (no significant warning for ground crews and the road commission). Hopefully I get hammered with this storm, my area kind of missed out on the Blizzard of 1999 (we only got 10 inches), whereas Chicago got just over 24 inches.
 
Anybody still use the traditonal empircal techniques when
its comes to forecasting winter precipitation:

Examples:
Cook Method
Garcia Method
LEMO
Magic Chart by Chaston
and so on

Mike
 
Anybody still use the traditonal empircal techniques when
its comes to forecasting winter precipitation:

Examples:
Cook Method
Garcia Method
LEMO
Magic Chart by Chaston
and so on

Mike
Click to expand...

I no longer use those methods, each of them seem to miss one feature or another. First, I look at QPF and basic temp profiles to determine the threat area. Then I look at low level vertical velocity, troughs, low tracks, and the thermal/moisture profile (mixing ratios, PWAT values just south of the baroclinic zone, etc.). Looking at isentropic data is also a must, and using cross sections to idenfity any instability (CSI), which may lead to thundersnow, and enhanced snowfall rates. I usually will wait until 12 hours before the event, and use the closes model data for making an in depth analysis, so nothing on this storm yet, as there is still room for pretty big changes.

I just got done looking at the ETA and GFS, and the GFS did a much better job with the trough in the west. The ETA is too weak, and doesn't extend the 546 height far enough southwest, so chances are, the GFS will depict a more accurate picture (not too mention, the GFS was on the money all along, and the ETA just recently trended towards it).

EDIT:

Anyone know why the GFS has a broad area of 110-130knt jet diving into the west at 300mb during the 00Z timeframe, but then by 06Z it dramatically weakens it (down to a small area of 90-110knts)? I don't know if that's realistic, do jet streams weaken that rapidly?
 
Okay... I'm gonna say the GFS model has the best depiction of things. It starts off with a better initialization with the 500mb heights (right on the money as far as the obs are concerned), where the ETA is too weak and too far northeast. Also making me lean towards the GFS, is the fact that it has been depicting this solution for quite some time (except for the brief eastward trend yesterday). All of the other models are essentially following along with the GFS. However, one thing that could be a plus for the ETA is it's usually better with low level thermal fields/baroclinic zones, which will also influence the track (since the storm is running into cold air, it may tend to track further east)... Time will tell of course...

The GFS then takes the system through the southern plains, while the 200-250mb jet rapidly strengthens to 150knts. This ultimately causes the storm to deepen, and allow for a further northwest track. All of the models have been conistant in making the upper level jet stream stronger with each run, so the storm could actually be a touch stronger than the GFS and a bit further northwest.

GFS QPF is nearly identical to it's 18Z run, with 1.00 to 1.25 inches falling on the cold side of the system from IN northeast through Ontario Canada... With 850mb temps of -8C or lower, and SFC temps in the low to mid 20's, this should result in 15:1 or 18:1 snow ratios. Winds will also be picking up, in the 30-40MPH range, so it's gonna be nasty, and possibly getting very near blizzard criteria...

That's all for my current wishcast...
 
Mesoscale models really going bonkers with this storm, deepening it to sub 990MB -- The FSL RUC and the WRF model (run by NASA). I have noticed that these models usually do well in high amplitude patterns, where the ETA and GFS have some problems... QPF on these models are very similar to the GFS though...

I am thinking a general 12-18 inch snowfall is in store for southern/eastern IN, western/northern OH, and southeastern MI. The OH/IN areas will generally have more QPF, but the snow ratios will be a bit lower, whereas MI will have less QPF, but snow ratios will be a bit higher. I could see a few locations in OH reaching the two foot threshold, or perhaps slightly more, where mesoscale banding sets up... FSL RUC also picks winds up into the 25-35knt range, which would qualify for blizzard status, when combined with the wind chills, and low visibilities...

And now, it's time for bed so I can wake up and check the 06Z models, and see how they have blow apart the storm... :lol:
 
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