Absolute Vorticity

Posted: **Mon Dec 19, 2022 11:34 am**

Plenty of talk about the 1978 blizzard and it shut everything down. Only 8 inches of snow but it was a quick 8 inches that fell and of course with rain much of the day with a quick changeover to sleet for about 15 minutes and then the heavy snow it was almost impossible to go anywhere. The flash freeze is imo the biggest problem. I have seen snow showers happening in late afternoon on a cold day almost shut down the town and that is because ice is just not a good thing and with all the hills around here makes it worse. Check out the nam and it really has the northern energy strong on Wednesday and then it does its normal nam thing and anybody's guess. I will check out the other models in a couple of hours to see if we see any differences that would affect the storm.

Posted: **Mon Dec 19, 2022 11:53 am**

I’ve had a running forecast of 1-3” since Saturday and I’m going to hold with that. This is a tricky storm, featuring a setup we have not seen in a long, long time.

Posted: **Mon Dec 19, 2022 11:55 am**

holy cow those temps and windchills on the backside are gonna leave a mark. if you haven't felt cold your gonna really feel it on Friday

Posted: **Mon Dec 19, 2022 11:57 am**

This will be a high-impact event for a ton of people, even if certain areas don’t see the huge dump of snow. That transition from rain to a period of heavy snow with rapidly falling temps and high winds will be no joke. Flash freeze is something I was discussing with Les the other night on the phone and I am still very much worried about that.

Posted: **Mon Dec 19, 2022 11:58 am**

I should say that the trend has been NE instead of due East on some guidance here. Sorry if I misspoke earlier. Like the GEFS for example, the 6Z had the low located S of Chicago. 12Z now has it NE of there over SW Lower Michigan. So we might be seeing a trend here where the storm is a bit weaker overall, and it takes a longer time to ramp up. So it will be more East as a result if this is correct. SE if better for us, and the correction might be to the NE in the guidance today. Again, sorry for the misinterpretation. I wanted to clarify that.

Posted: **Mon Dec 19, 2022 11:59 am**

Trevor wrote: ↑Mon Dec 19, 2022 11:57 am This will be a high-impact event for a ton of people, even if certain areas don’t see the huge dump of snow. That transition from rain to a period of heavy snow with rapidly falling temps and high winds will be no joke. Flash freeze is something I was discussing with Les the other night on the phone and I am still very much worried about that.

Oh yeah... I haven't changed my mind on the wind, temp drop etc etc. Not so sure on the flash freeze part though now as I was then when we spoke, because the dry slot would lend some assistance with that.

Posted: **Mon Dec 19, 2022 11:59 am**

The extent of winter weather headlines (winter weather advisories, storm warnings, wind chill advisories, etc) from multiple weather offices will be quite something with this.

Posted: **Mon Dec 19, 2022 12:01 pm**

tron777 wrote: ↑Mon Dec 19, 2022 11:59 am
Trevor wrote: ↑Mon Dec 19, 2022 11:57 am This will be a high-impact event for a ton of people, even if certain areas don’t see the huge dump of snow. That transition from rain to a period of heavy snow with rapidly falling temps and high winds will be no joke. Flash freeze is something I was discussing with Les the other night on the phone and I am still very much worried about that.
Oh yeah... I haven't changed my mind on the wind, temp drop etc etc. Not so sure on the flash freeze part though now as I was then when we spoke, because the dry slot would lend some assistance with that.

If we weren’t to get that transition from rain to a burst of snow behind the front, I would agree with you. But a layer of snow on top of rain and falling temps will not be dried up by the wind like it would be if it was just rain to nothing.

Posted: **Mon Dec 19, 2022 12:18 pm**

Trevor wrote: ↑Mon Dec 19, 2022 11:53 am I’ve had a running forecast of 1-3” since Saturday and I’m going to hold with that. This is a tricky storm, featuring a setup we have not seen in a long, long time.

It's not very often we see 1-3" of snow post-frontal like this, but so far every model is showing it. I also believe that many areas will see additional accumulations from areas of snow/snow showers coming off the lakes that the models just can't pick up on.

Posted: **Mon Dec 19, 2022 12:25 pm**

dce wrote: ↑Mon Dec 19, 2022 12:18 pm
Trevor wrote: ↑Mon Dec 19, 2022 11:53 am I’ve had a running forecast of 1-3” since Saturday and I’m going to hold with that. This is a tricky storm, featuring a setup we have not seen in a long, long time.
It's not very often we see 1-3" of snow post-frontal like this, but so far every model is showing it. I also believe that many areas will see additional accumulations from areas of snow/snow showers coming off the lakes that the models just can't pick up on.

I suspect most will see a quick inch or two post frontal. Then additional light accumulation on Friday. Should allow for most to see 1-3” in total. Maybe a bit more north of town.

Posted: **Mon Dec 19, 2022 12:26 pm**

GEFs track cluster

gfs-ememb_lowlocs_us_fh60-90 (1).gif

Posted: **Mon Dec 19, 2022 1:16 pm**

One thing going for the Flash Freeze idea is the rate at which the temp drops. We will have a better idea on that once this gets a little more into the short term / mesoscale model range. With the globals we get 3 to 6 hour increments. Hourly increments will be more useful in another day or two to calculate how fast the temp actually drops. I saw a model that has it dropping 50 degrees in like 6 hours! I think it was the UKMET. That would do it dry slot or no dry slot. I mean if we're talking a 20 degree drop in 30 mins we are in trouble with things icing up. A strong wind can dry things fast but if the temp drop is faster then the wind can dry, then there you go. So that is something we need to calculate to really start honking about it.

The wind is worth honking about and the risk of power outages due to down trees / limbs. Leaves are basically off now minus a few oaks so that helps, but any old or weak trees will be problematic in some areas. Then with the cold air rushing in your home will cool off quickly. Have a generator, a kerosene heater, etc. some way of getting alternative heat. There is also a fire risk here so def use common sense and make sure it's well ventilated. Don't set it on carpet or anything that can catch fire. Make sure it isn't too close to a wall, etc etc. Common sense stuff.

Now thru Wednesday is the time to prepare and have a game plan. Get food, alcoholic beverages

medicines, cash, charge those cell phones on Thursday... make sure your car is filled up, that never hurts. Etc. Etc. That is my message for today. These are the highest impacts in my opinion based on the data I have seen. Snow, low visibilities are secondary impacts.

Posted: **Mon Dec 19, 2022 1:21 pm**

12Z Euro nearly identical to its 0Z run.

Posted: **Mon Dec 19, 2022 1:27 pm**

tron777 wrote: ↑Mon Dec 19, 2022 1:16 pm One thing going for the Flash Freeze idea is the rate at which the temp drops. We will have a better idea on that once this gets a little more into the short term / mesoscale model range. With the globals we get 3 to 6 hour increments. Hourly increments will be more useful in another day or two to calculate how fast the temp actually drops. I saw a model that has it dropping 50 degrees in like 6 hours! I think it was the UKMET. That would do it dry slot or no dry slot. I mean if we're talking a 20 degree drop in 30 mins we are in trouble with things icing up. A strong wind can dry things fast but if the temp drop is faster then the wind can dry, then there you go. So that is something we need to calculate to really start honking about it.

The wind is worth honking about and the risk of power outages due to down trees / limbs. Leaves are basically off now minus a few oaks so that helps, but any old or weak trees will be problematic in some areas. Then with the cold air rushing in your home will cool off quickly. Have a generator, a kerosene heater, etc. some way of getting alternative heat. There is also a fire risk here so def use common sense and make sure it's well ventilated. Don't set it on carpet or anything that can catch fire. Make sure it isn't too close to a wall, etc etc. Common sense stuff.

Now thru Wednesday is the time to prepare and have a game plan. Get food, alcoholic beverages medicines, cash, charge those cell phones on Thursday... make sure your car is filled up, that never hurts. Etc. Etc. That is my message for today. These are the highest impacts in my opinion based on the data I have seen. Snow, low visibilities are secondary impacts.

Great points as always, Les. I have high confidence that the rate of fall in terms of temperatures is going to nothing short of tremendous, and something we don’t see all that often around here.

Posted: **Mon Dec 19, 2022 1:29 pm**

Euro solution would drop an inch or two basically along and NW of the I-71 corridor and 2-3" for I-70 Crew. Your 4" line and up NW of IND Metro. Something like that. Seems fair given the low tracking to our West which is never going to work for heavy snows anyway.

Posted: **Mon Dec 19, 2022 1:30 pm**

Yea , not much change in EU again. Verbatim, after the change over to snow ,looks like a .10"- .25" leftover QPF for the region.

Posted: **Mon Dec 19, 2022 1:33 pm**

Hard to argue with the consistency of the Euro.

Posted: **Mon Dec 19, 2022 1:34 pm**

Trevor wrote: ↑Mon Dec 19, 2022 1:27 pm
tron777 wrote: ↑Mon Dec 19, 2022 1:16 pm One thing going for the Flash Freeze idea is the rate at which the temp drops. We will have a better idea on that once this gets a little more into the short term / mesoscale model range. With the globals we get 3 to 6 hour increments. Hourly increments will be more useful in another day or two to calculate how fast the temp actually drops. I saw a model that has it dropping 50 degrees in like 6 hours! I think it was the UKMET. That would do it dry slot or no dry slot. I mean if we're talking a 20 degree drop in 30 mins we are in trouble with things icing up. A strong wind can dry things fast but if the temp drop is faster then the wind can dry, then there you go. So that is something we need to calculate to really start honking about it.

The wind is worth honking about and the risk of power outages due to down trees / limbs. Leaves are basically off now minus a few oaks so that helps, but any old or weak trees will be problematic in some areas. Then with the cold air rushing in your home will cool off quickly. Have a generator, a kerosene heater, etc. some way of getting alternative heat. There is also a fire risk here so def use common sense and make sure it's well ventilated. Don't set it on carpet or anything that can catch fire. Make sure it isn't too close to a wall, etc etc. Common sense stuff.

Now thru Wednesday is the time to prepare and have a game plan. Get food, alcoholic beverages medicines, cash, charge those cell phones on Thursday... make sure your car is filled up, that never hurts. Etc. Etc. That is my message for today. These are the highest impacts in my opinion based on the data I have seen. Snow, low visibilities are secondary impacts.
Great points as always, Les. I have high confidence that the rate of fall in terms of temperatures is going to nothing short of tremendous, and something we don’t see all that often around here.

Thanks Trev! If this temp drop is that tremendous that the flash freeze is going to be there for sure. It's just something that is hard to even think of, let alone put in a forecast since it rarely ever happens. I can only think of one or two events like that in my 40 plus years of living in this area. But at the same time, we're not dealing with a run of the mill storm either if this thing bombs out as advertised. I mean a 1060 something MB high on its Western side and a 1040s MB high in Quebec. This storm should have been an Apps Runner for us with that huge banana shaped high like that! But nope, the Pacific had to go and shoot that PNA ridge just off the West Coast instead of right along it where we needed that. That little bump to the West and boom... this thing wraps up in ILL, IN, and MI instead of TN, WVA, SE Ohio or NW PA. Sigh....

Posted: **Mon Dec 19, 2022 1:36 pm**

mainevilleweather wrote: ↑Mon Dec 19, 2022 1:33 pm Hard to argue with the constancy of the Euro.

I'm doing this

but not at the Euro. It's been rock solid minus a few blip East Coast runs that made DT fail, and fail royally.

Posted: **Mon Dec 19, 2022 1:40 pm**

tron777 wrote: ↑Mon Dec 19, 2022 1:36 pm
mainevilleweather wrote: ↑Mon Dec 19, 2022 1:33 pm Hard to argue with the constancy of the Euro.
I'm doing this but not at the Euro. It's been rock solid minus a few blip East Coast runs that made DT fail, and fail royally.

Yea ,I'm sorry , I can't believe the play these big names get , eventually these guys are right once in a blue.moon and everyone forgets how wrong they often are

Posted: **Mon Dec 19, 2022 1:41 pm**

Any chance that low hangs up in Michigan for a while and spins? Isn't that what happened in 78'?

Posted: **Mon Dec 19, 2022 1:43 pm**

We can talk about this in the December thread, or make a new thread later whatever... but I am watching a possible consolation prize clipper perhaps, just after Christmas. A signal for something dropping down in NW flow is there, but what it not clear is what happens to it? Does it phase with anything down by the Gulf in the STJ? Does it harmlessly move thru as the typical 1-3" clipper? Or does it shear out and fall apart into nothing? No idea right now here and the models don't have a clue either. Nothing will come into focus down the road until this big ole blizzard gets out of the way. We will see blizzard watches and eventually warnings issued with this system on its Western and NW side. My guess right now for that is a St Louis to Chicago to Upper Michigan Line and some parts of Wisc as well. Probably winter storm watches to warnings and advisories all other areas. Just kind of a rough outline of how a weather map over the Lower 48 might look for this one. Probably some wind chill advisories and warnings going up later also. I could see us getting into the wind chill game. Not sure how ILN would go with winter storm headlines though. The wind wants you to issue the B word but the amounts of snow aren't really winter storm warning criteria either at this time. Tough call for the NWS without a doubt.

Posted: **Mon Dec 19, 2022 1:46 pm**

tron777 wrote: ↑Mon Dec 19, 2022 11:58 am I should say that the trend has been NE instead of due East on some guidance here. Sorry if I misspoke earlier. Like the GEFS for example, the 6Z had the low located S of Chicago. 12Z now has it NE of there over SW Lower Michigan. So we might be seeing a trend here where the storm is a bit weaker overall, and it takes a longer time to ramp up. So it will be more East as a result if this is correct. SE if better for us, and the correction might be to the NE in the guidance today. Again, sorry for the misinterpretation. I wanted to clarify that.

Hey Les and I don't believe its the wrong interpretation. Models will have a hard time figuring out where a low pressure will end up. This is not your normal Canadian cold air mass and if this one bombs out you may not noticed a northwest shift with the low because the front is so powerful and quick moving that everything including the low is moving. I will say one thing about the Euro and is had very little movement in the last several days. The CMC which led the way into this pattern has been back and forth but still not horrible but the gfs is like me throwing darts and I can tell you I am not very good at throwing darts. I hope to have my forecast sometime Tuesday afternoon and was hoping around 2pm but I have a meeting at 1pm and may not be until 3 or 4pm. Concerning flash freeze and if we don't get that I will be surprised and again when we have the occlusion is key and with a really wrapped up storm that just got underway I believe this process takes longer. Going from say 45 to 15 in 2-3 hours and you will have a flash freeze and hopefully a decent period of snow on top of the ice for traction. Again not like 1978 when you had heavy rain and a brief but heavy bout with sleet and a quick 8 inches of snow and then everything just froze over.Btw the way the winds will be wild and the Bengals play New England on Saturday and winds at times could gust over 70mph and I say hello run game

Posted: **Mon Dec 19, 2022 1:47 pm**

Bgoney wrote: ↑Mon Dec 19, 2022 1:40 pm
tron777 wrote: ↑Mon Dec 19, 2022 1:36 pm
mainevilleweather wrote: ↑Mon Dec 19, 2022 1:33 pm Hard to argue with the constancy of the Euro.
I'm doing this but not at the Euro. It's been rock solid minus a few blip East Coast runs that made DT fail, and fail royally.
Yea ,I'm sorry , I can't believe the play these big names get , eventually these guys are right once in a blue.moon and everyone forgets how wrong they often are

I like the comment that Tim uses. He is good at long range forecasting. Not so much with individual storms. Long range and seasonal forecasting is more his bag. I think JB is similar to that. People are better off listening to their local Mets (like we do with CB, BG, John Gumm etc) they all have experience with how a lot of our weather patterns are. Folks like DT and JB have no idea since they are long range guys. I love forecasting the long range. Sometimes, the medium and short range can even be more difficult. It's easy sometimes to see a certain pattern coming. It's very tough to see how an individual storm will react to it.

Posted: **Mon Dec 19, 2022 1:49 pm**

mainevilleweather wrote: ↑Mon Dec 19, 2022 1:41 pm Any chance that low hangs up in Michigan for a while and spins? Isn't that what happened in 78'?

That track was way more East then this one will be. It bombed out over CLE and Upstate PA / NY. Cincy got like 8". This one bombs out in IN or Michigan thus much lower amounts like an inch or two. It all matters how fast this thing wraps up to figure out where it's going to go.

Absolute Vorticity

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