I still don't know what I was waiting for And my time was running wild A million dead-end "models" Every time I thought I'd got it made It seemed the taste was not so sweet So I turned myself to face me But I've never caught a glimpse Of how the others must see the "GFS" in me. I'm much too fast to take that "run"
Ch-ch-ch-ch-Changes (Turn and face the change) Ch-ch-Changes Don't want to be a rainy man Ch-ch-ch-ch-Changes (Turn and face the strain) Ch-ch-Changes Just gonna have to be a different pattern Time may change me But I can't trace time
I will tell you that this is not going to be a boring pattern for the rest of December. A few days ago I talked about BACK END snow and this still sits in my mind this morning as we see a transition from Mild to Cold on the indices and the storm track.
We have a few things going in our favor but we don't have the timing of it all just perfect...just yet on the NAO and AO combo snow blower.
The GFS is does not look totally right here. I just can't justify all the 540 (red dotted lines) all over the place. I still think this model is making errors and will try to adjust over the weekend.
The CMC or Canadian is now in the GFS world of taking a storm and wrapping in the cold as it is delayed until the passing of the storm in the I-95 region.
This would bring back end snow even to the I-95 but not a ton just a small snow event at this point. NE PA, Upstate NY and parts of New England would have the best chance of several inches of snow.
The EURO or ECMWF shows a back end of cold after the track moves into New England. Not the best track if you want a decent snow from NYC south but all the models do show a storm the middle part of next week.
MY THINKING AT THIS POINT...
We just simply can't write off any snowstorm potential from December 18 to December 31 at this point. The AO or Arctic Oscillation will send down some cold over the next 17 days so bank on it getting colder in the Midwest and East.
The storm track is still not etched in stone so a shift of 50-100 here or there with some supported cold can change a forecast very quickly.
My gut says December 19th is a small event of snow for NYC south and more in Northern New England.
The real payoff for snow lovers is December 21-23 as the storm track finally gets the support it from the cold air and than simply means GAME ON.
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Happy to help! I am not currently blogging..but I will be within a few weeks on my soon-to-be website, www.WeatherTalk.tv !! In the meantime, here are some cool links for checking out the 1000-850mb thickness (130 dkm critical) and the 850-700 mb thickness (154 dkm critical). Start with this data for NYC from this morning's (12/19) ETA run: http://126.96.36.199/text/NAM80km/NAM_knyc.txt
If the critical thickness for the two layers are in conflict, i.e., the lower one shows "snow (less than or = 130)" while the upper one shows "borderline (= or above 154)," look at the temps at the individual pressure layers to see if the mild layer is deep enough to melt falling snow.
Here's the data from the GFS: http://beta.wxcaster.com/text/gfs/GFS_KNYC.txt Delete and replace the 3-letter ID for any station you're interested in.
Let me know if this helps! Happy forecasting, Michael
Mike F I would love to read more of the subject matter you touched on. Any chance of you doing a blog on layer conditions needed to support snow and where one might find the needed model links to keep track of such things as a storm approaches?
Yes, Rob's explanation is good, I just wanted to set the table for him to go, maybe, to the next level if he wishes.
At this time, OakMAN, I must confess that you have "outed" me. I am now "out of the closet" -- as a snow *hating* meteorologist! Give me last winter's pattern, any time -- give me sunshine and warmth!
As I watch these model runs along with Rob and all of you, I am actually rooting for these coastals to "just miss" my neighborhood (southwestern CT), weaken, not tap the arctic air, not form that secondary circulation, take a turn slightly more inland or southward, etc.
But it's all in fun. Since none of us can actually, physically, do anything about it, we can go on together just watching how these things unfold and learn. What the hay, right? (I actually do root for *lots* of snow to fall on all of the popular ski resorts, though -- and since I can't beat it, I can only join it, so I have taken up skiing, both downhill and Nordic ;) )
Ok; can we think of the 19th storm as an appetizer for the main event maybe on the 23 rd or around there? Time will tell. Oak,good to see you back and your ideas on the storms. Still way too early for anything for sure for next weekend, but its fun to think about it.
I know that the storms are several day's out & have plenty of time to change from now to then probably several times....but if either storm develops as your expecting is Tn, Va or Charlotte area expected to get any snow from these storms?
Philly- that run of the gfs does have cold air, just no disturbances. It shows the tanking AO and the loss of the -NAO that we have had around for a while. The Pacific looks a marginally better but at the same time we are losing our block in long range. It will certainly be colder around Xmas that much appears fairly certain on all the models. I think the models are absolutely struggling and I am fairly confident that after this weekend and next weeks event they will probably look totally different :)
If you are a snowlover you better cover your eyes before looking at the latest GFS(12Z) run. It is a massacre to any snow chances. I'm not saying it is right, but I will say it isn't pretty! The models are obviously struggling with the pattern, but I'm thinking we may be at least 10 days away from any legit snow chances around here. I only say that because there seems to be a serious lack of cold air in the pattern up until then.
I never like the thread the needle storms(I know people hate that phrase). I pay attention when the cold air is in place ahead of the storm. That is when I say game on!
Michael, I thought Rob did do a great job of explaining. Yes models are what they are but this time of year the models are great to show patterns and if these long range models continue to show storms as we obviously will get colder going into the REAL winter period.....that's a very good sign!!
Let's educate the weather-enthusiast audience a little finer, so-to-speak.
Being "to the left of" or "west of" the 540 red line is a GENERAL first step. But, as you know, it can rain, too, west/north of 540 just as easily, or snow east/south of it.
You have to look at a finer resolution of the layers through 540 decameters of airmass thickness. You also have to look at the thickness of the 1000-850 layer and the 850-700 layer. This is critical, esp. in "borderline" situations such as the one impending for next Tues./Wed.
You may want to talk about this with your next blog. Research has shown the critical thickness for rain vs. snow to be: about 130 dkm and 154 dkm for 1000-850 and 850-700 layers, respectively.
As you said, the models are a little sketchy for this next potential event, and yes, it can get vexing when you can't pinpoint it several days in advance. But, it is what it is: as wonderful as the models can be, we have to live with their limitations, and be honest about them with our weather info-consuming audience.
The 19th threat = insert fork it's way too warm. We never had much of a shot without some real cold air source nearby and we lost some of our block that was modeled as well. Time to look further ahead and see what we have beyond b/c we should finally have some realtively cold air around to work with. We all need a snowy Xmas present in this area badly. I bought a snowblower over a year ago and I haven't used it yet and I feel like I am cursed b/c of it!