Absolute Vorticity

The latest thinking from the boys:

Rain will be crossing the area on Thursday, with greater coverage
and amounts occurring in the morning in eastern counties as low
level jet translates eastwards and weakens. Guidance is suggesting
that there could be some drying, or at least much lower coverage,
from Thursday afternoon until the arctic front crosses the region
Thursday night.

12Z models have continued a trend of being ever so slightly faster
with the progression of the front. Still looking at a rain rapidly
changing to snow scenario with temperatures plummeting and winds
increasing substantially once the front moves through. Appears that
there could be a decent band of heavier snow that follows the front.
That is expected to be short-lived, although there are still come
uncertainties how quickly drying punches into the area, which
affects how much snow ends up falling. At this point, thinking that
snowfall amounts will be in the advisory range. However, with the
falling temperatures, strong winds, and resultant very cold wind
chills, there will likely be travel impacts across the entire area.
It is more a question of to what degree. Have opted to go with a
longer lead time winter storm watch for where the juxtaposition of
these conditions likely will have the greatest impact. Obviously,
there are many details still to be resolved.

It is quite clear that it will be very cold. Wind chill headlines,
probably within advisory range, will be needed Friday night and
Saturday. Those may even extend into Saturday night and Sunday
although winds will be decreasing as high pressure builds into the
region by that point.

Good Afternoon and tons of info to go over and I should have more time this evening and Wednesday. Still I believe the main problem is the flash freeze. Models are having a hard time in where to close of the low and in this type of situation I understand completely. The cold is moving like a freight train and its hard for these lows to cut off and that is why you will see those lows pop everywhere on the map. Yes still over 48 hours away from the changeover and at the moment Les your 1-4 looks good. I am just not sold yet on where the 1 is and where the 4 will be located. Many times a cold front comes through and you see a few hours where it has a hard time getting through the app mountains and this can add a little extra time of snowfall for eastern Kentucky and southeast Ohio. The problem this time is the cold is so strong that the mountains may not even be able to hold back the cold from crossing them in a timely matter. I will post more later and by then will have looked at the models.

Blizzard Warnings going up in Minnesota

tpweather wrote: ↑Tue Dec 20, 2022 4:25 pm Good Afternoon and tons of info to go over and I should have more time this evening and Wednesday. Still I believe the main problem is the flash freeze. Models are having a hard time in where to close of the low and in this type of situation I understand completely. The cold is moving like a freight train and its hard for these lows to cut off and that is why you will see those lows pop everywhere on the map. Yes still over 48 hours away from the changeover and at the moment Les your 1-4 looks good. I am just not sold yet on where the 1 is and where the 4 will be located. Many times a cold front comes through and you see a few hours where it has a hard time getting through the app mountains and this can add a little extra time of snowfall for eastern Kentucky and southeast Ohio. The problem this time is the cold is so strong that the mountains may not even be able to hold back the cold from crossing them in a timely matter. I will post more later and by then will have looked at the models.

A fair and good assessment Tim! There is definitely some wiggle room here especially in our NW counties.

snowbo wrote: ↑Tue Dec 20, 2022 4:27 pm Blizzard Warnings going up in Minnesota

Going to be a lot more pinks and reds come tomorrow.

I see that and they expect 5-8 inches but my guess liquid that is probably in the neighborhood of .25. This is the kind of storm where snow ratios that we normally see around here are 10-1 and would not be surprised to see them in the 20-1 or even 25-1. So even with 1/10 of an inch of liquid we are talking 2 - 2 1/2 inches. I understand when it first starts to snow that ratio may be 10-1 but with this kind of cold that is going up in a hurry. Storms have hiccups and especially when they try and close off a upper system. Somebody is going to get lucky and be in that sweet spot and get 10 inches but is that in northwest Indiana or central Illinois or someplace else and that is the problem until the storm gets closer. Again not the 78 blizzard but the storm was on nobody's radar 48 hours in advance and even within 24 hours the info was still off quite a bit. The big difference with this storm and the 78 storm is moisture and with that storm there was tons before the cold and decent amount right after the front went through but again the amount of hours that it snowed during the storm was probably 4-6 hours.

The lack of moisture with this system is indeed the bummer part. If only we could have gotten the phase when we had that Apps runner look a few days ago.

EPS 12z cluster, can't get much tighter

18Z GFS is a bit slower digging down across the Rockies and a tad NW with the low track as compared to the 12Z run. The model is struggling with the placement of the low when it really bombs out and you can tell that by the odd "low jumping" that it's doing at 66-72 hours. A little more QPF too... 12Z run approx had 0.17" for CVG to work with in the cold sector. 18Z GFS now spitting out over the 0.20" mark.

Good news is it looks like we assured of a white Christmas this year. Sure beats 70 degrees and sunny that we had a few times the last several years

tron777 wrote: ↑Tue Dec 20, 2022 4:59 pm 18Z GFS is a bit slower digging down across the Rockies and a tad NW with the low track as compared to the 12Z run. The model is struggling with the placement of the low when it really bombs out and you can tell that by the odd "low jumping" that it's doing at 66-72 hours. A little more QPF too... 12Z run approx had 0.17" for CVG to work with in the cold sector. 18Z GFS now spitting out over the 0.20" mark.

Les .20 in this kind of cold will put us in the 2-4 inch area and maybe a tad more. Again when and where the low closes off those folks just to the northwest of that will get hit hard but before it closes off folks in Iowa,Missouri will end up with similar amounts imo that we end up with. Going to be a wide band of 2-5 inches imo from the plains into the Ohio Valley and then the few lucky areas that gets the timing correct with the low closing off that can get that 6-10 inches. Of course folks up in Michigan will continue to get wrap around snows that can add another 3-6 inches because of the high ratio's. This is probably going to be my forecast and the only thing will need to adjust is when and where that low closes off and once that is set in stone sort of then narrow down where the heaviest snows fall.

Nice analysis from Ryan Hall, slim secondary low over Apps? Slim chance, but a chance….

Robejoh76 wrote: ↑Tue Dec 20, 2022 6:20 pm Nice analysis from Ryan Hall, slim secondary low over Apps? Slim chance, but a chance….

You're about 5 hours late on that. It's 3-4 pages back.

Good evening all! Been out looking at lights and eating some grub. Will check out some more data when I get home here shortly.

ILN is doing a FB live at 8:00 to talk about the storm.

kywthrluvr wrote: ↑Tue Dec 20, 2022 7:33 pm ILN is doing a FB live at 8:00 to talk about the storm.

Do you no the link?

mikeyp wrote: ↑Tue Dec 20, 2022 7:35 pm

kywthrluvr wrote: ↑Tue Dec 20, 2022 7:33 pm ILN is doing a FB live at 8:00 to talk about the storm.

Do you no the link?

I follow them on FB and saw it posted there.

mikeyp wrote: ↑Tue Dec 20, 2022 7:35 pm

kywthrluvr wrote: ↑Tue Dec 20, 2022 7:33 pm ILN is doing a FB live at 8:00 to talk about the storm.

Do you no the link?

I shared it on my Facebook page for anyone who is my friend. I'll share it on our AV Facebook page as well.

The Euro might be caving finally on that farther NW track. 18Z run made a major move SE. Low tracks thru SE IN counties to Toledo. It takes much longer for it to get ramped up. This is exactly what you want to see for snow lovers. More backside precip to work with. Going to say here that for CVG as an example, we now have over 0.30" to play with. If this is correct. It may be. That has been the trend today. Let's see if 0Z holds or if it continues with just about a full sampling now taking place tonight and 100% tomorrow at 12Z.

18Z Euro backside precip and snowfall Kuchera maps. Wow!!!

tron777 wrote: ↑Tue Dec 20, 2022 8:16 pm The Euro might be caving finally on that farther NW track. 18Z run made a major move SE. Low tracks thru SE IN counties to Toledo. It takes much longer for it to get ramped up. This is exactly what you want to see for snow lovers. More backside precip to work with. Going to say here that for CVG as an example, we now have over 0.30" to play with. If this is correct. It may be. That has been the trend today. Let's see if 0Z holds or if it continues with just about a full sampling now taking place tonight and 100% tomorrow at 12Z.

Hey Les I gave my forecast out earlier and when all is said and done will the CMC outdo the other 2 models once again. I stand by forecast and of course the main reason has always been the type of cold air mass we are seeing. So 2-5 inches in a wide area from the northern and central plains into the Ohio Valley and then a smaller area where the low finally closes off and the area just northwest of there could be in the 6-10 inch range. Again its no such much about snow totals but what the conditions will be once the snow starts flying.

tpweather wrote: ↑Tue Dec 20, 2022 8:21 pm

tron777 wrote: ↑Tue Dec 20, 2022 8:16 pm The Euro might be caving finally on that farther NW track. 18Z run made a major move SE. Low tracks thru SE IN counties to Toledo. It takes much longer for it to get ramped up. This is exactly what you want to see for snow lovers. More backside precip to work with. Going to say here that for CVG as an example, we now have over 0.30" to play with. If this is correct. It may be. That has been the trend today. Let's see if 0Z holds or if it continues with just about a full sampling now taking place tonight and 100% tomorrow at 12Z.

Hey Les I gave my forecast out earlier and when all is said and done will the CMC outdo the other 2 models once again. I stand by forecast and of course the main reason has always been the type of cold air mass we are seeing. So 2-5 inches in a wide area from the northern and central plains into the Ohio Valley and then a smaller area where the low finally closes off and the area just northwest of there could be in the 6-10 inch range. Again its no such much about snow totals but what the conditions will be once the snow starts flying.

I've been noticing slight improvements in the PNA ridge today. Closer to the West Coast instead of well offshore, which is the main priority as we've discussed. Then, the shortwave is a bit slower so it's weaker and takes a longer period of time to get cranked up. This allows for a further SE track. Add into the fact that you mentioned about the dense cold air. That is speeding up the frontal passage. All of these little things MIGHT add up to more snow for us. I am not changing my call tonight. Let's see what tonight and tomorrow does then we can get a little more pumped up here!

We may see that East Coast low development after all. 18Z Euro on the above panel is showing that. This also keeps the storm a bit weaker, longer. Very very interesting trends today. Again, let's see if they hold or improve.

Les always stick by your forecasts. We may go about it in different ways which imo is wonderful. Do I listen to what other folks mention and the answer is yes and many times I will miss something and somebody will point something out and that can change my forecast. I have a long list when I make a forecast and sure give out what I see well in advance but once I make a forecast like I did tonight its really what I believe the final outcome will end up being. Can something change in the next 48 hours and sure and the only thing I left on the table is when and where the upper low closes off because then I will need to adjust the area to the north and west and add more snow. I don't think it will be a broad area because at the end of the day this front is still moving even with a low pressure forming somewhere on the front but it does slow up enough for several hours to give those places several hours of heavy snow.

tpweather wrote: ↑Tue Dec 20, 2022 8:36 pm Les always stick by your forecasts. We may go about it in different ways which imo is wonderful. Do I listen to what other folks mention and the answer is yes and many times I will miss something and somebody will point something out and that can change my forecast. I have a long list when I make a forecast and sure give out what I see well in advance but once I make a forecast like I did tonight its really what I believe the final outcome will end up being. Can something change in the next 48 hours and sure and the only thing I left on the table is when and where the upper low closes off because then I will need to adjust the area to the north and west and add more snow. I don't think it will be a broad area because at the end of the day this front is still moving even with a low pressure forming somewhere on the front but it does slow up enough for several hours to give those places several hours of heavy snow.

If we can get a 6 hour period of mod to hvy snow with these winds and bitter temps... (Of course, the more the better for me LOL) it's going to be one hell of a sight to see! Even when the snow shuts off, the winds will still be horrible for a long period of time. Saturday won't be a heck of a lot better then Friday. Should improve some by Christmas Day.