Absolute Vorticity

tron777 wrote: ↑Wed Feb 14, 2024 12:25 pm I have no clue on the accuracy of the hi Res FV3 as it's an experimental model, but the 12Z run has jumped well north to match the RGEM. A nice 2-4" thumping is being shown for the Tristate area.

Ok Les, let's just leave it at that with the hi Res FV3, CMC and the RGEM. We should just not look at any more models for this event and run with it!

winterstormjoe wrote: ↑Wed Feb 14, 2024 12:47 pm

tron777 wrote: ↑Wed Feb 14, 2024 12:25 pm I have no clue on the accuracy of the hi Res FV3 as it's an experimental model, but the 12Z run has jumped well north to match the RGEM. A nice 2-4" thumping is being shown for the Tristate area.

Ok Les, let's just leave it at that with the hi Res FV3, CMC and the RGEM. We should just not look at any more models for this event and run with it!

Add the ICON to this list lol

tron777 wrote: ↑Wed Feb 14, 2024 12:03 pm

Trevor wrote: ↑Wed Feb 14, 2024 11:05 am Quite the boundary to work with here. With the cold high sitting further west, we need to watch and consider northward bumps in future runs. If the high were closer to us/to our north I would be more concerned about suppression. With such a stark contrast across the boundary, it would not surprise me if future runs came in stronger and further north with the track. The Gulf is open, and there is a connection. Not saying this is going to blow up into something crazy, but a stronger system/further north is a possibility. I have a south bias of course on my public forecast due to model trends, but we need to keep a close eye on this. I don't think we are done with the shifting. I could be very wrong here but just brainstorming all options.

What you said makes perfect sense and hopefully we see the ticks north tonight and tomorrow. On the other hand, the more energy that gets left behind, the weaker system we get and thus, a more SE track. So both scenarios make sense and are possible at this time. I also don't think the final track / strength is set in stone either. More changes are sure to come over the next 24 to 36 hours. You would think that the QPF would be better too thanks to the baroclinic boundary and if we can get any help from the Gulf too. But, as you said, we could be totally wrong here lol

Les I agree with you about the boundary and some help from the gulf looks possible. My biggest fear really is a north to northeast wind on Friday and just eats at the northern boundary of precip. Seen this and done that before. Hope I am wrong because to me everything else looks decent for at least some snow to fall.

Link is time sensitive but a lot of the energy for Friday's system can be seen here:

https://www.star.nesdis.noaa.gov/GOES/s ... &length=12

tpweather wrote: ↑Wed Feb 14, 2024 12:53 pm

tron777 wrote: ↑Wed Feb 14, 2024 12:03 pm

Trevor wrote: ↑Wed Feb 14, 2024 11:05 am Quite the boundary to work with here. With the cold high sitting further west, we need to watch and consider northward bumps in future runs. If the high were closer to us/to our north I would be more concerned about suppression. With such a stark contrast across the boundary, it would not surprise me if future runs came in stronger and further north with the track. The Gulf is open, and there is a connection. Not saying this is going to blow up into something crazy, but a stronger system/further north is a possibility. I have a south bias of course on my public forecast due to model trends, but we need to keep a close eye on this. I don't think we are done with the shifting. I could be very wrong here but just brainstorming all options.

What you said makes perfect sense and hopefully we see the ticks north tonight and tomorrow. On the other hand, the more energy that gets left behind, the weaker system we get and thus, a more SE track. So both scenarios make sense and are possible at this time. I also don't think the final track / strength is set in stone either. More changes are sure to come over the next 24 to 36 hours. You would think that the QPF would be better too thanks to the baroclinic boundary and if we can get any help from the Gulf too. But, as you said, we could be totally wrong here lol

Les I agree with you about the boundary and some help from the gulf looks possible. My biggest fear really is a north to northeast wind on Friday and just eats at the northern boundary of precip. Seen this and done that before. Hope I am wrong because to me everything else looks decent for at least some snow to fall.

A NE wind is good to lock in the cold air. To counteract the drier air, you need a good SW flow aloft then have the NE wind at the surface. That is how you get things done in the snow dept.

0Z Euro from last night had 0.15" for CVG. 6Z run was even worse, under a tenth of an inch. 12Z Euro now looks to have at least stopped the southward bleeding. It's back to showing 0.15" for CVG again.

tron777 wrote: ↑Wed Feb 14, 2024 1:10 pm 0Z Euro from last night had 0.15" for CVG. 6Z run was even worse, under a tenth of an inch. 12Z Euro now looks to have at least stopped the southward bleeding. It's back to showing 0.15" for CVG again.

Part of that qpf would get eaten up in the beginning with rain/mix since moisture arrives around or slightly before sunset

Bgoney wrote: ↑Wed Feb 14, 2024 1:21 pm

tron777 wrote: ↑Wed Feb 14, 2024 1:10 pm 0Z Euro from last night had 0.15" for CVG. 6Z run was even worse, under a tenth of an inch. 12Z Euro now looks to have at least stopped the southward bleeding. It's back to showing 0.15" for CVG again.

Part of that qpf would get eaten up in the beginning with rain/mix since moisture arrives around or slightly before sunset

True. I'm just happy to see the model hold serve with its overnight run. That right there is a victory lol

tron777 wrote: ↑Wed Feb 14, 2024 1:24 pm

Bgoney wrote: ↑Wed Feb 14, 2024 1:21 pm

tron777 wrote: ↑Wed Feb 14, 2024 1:10 pm 0Z Euro from last night had 0.15" for CVG. 6Z run was even worse, under a tenth of an inch. 12Z Euro now looks to have at least stopped the southward bleeding. It's back to showing 0.15" for CVG again.

Part of that qpf would get eaten up in the beginning with rain/mix since moisture arrives around or slightly before sunset

True. I'm just happy to see the model hold serve with its overnight run. That right there is a victory lol

No doubt, it’s desperation time

12Z UKIE looks better.... gives 0.20 to 0.30" to the area.

tron777 wrote: ↑Wed Feb 14, 2024 1:10 pm 0Z Euro from last night had 0.15" for CVG. 6Z run was even worse, under a tenth of an inch. 12Z Euro now looks to have at least stopped the southward bleeding. It's back to showing 0.15" for CVG again.

Looks like that’s about the range the EPS are showing

Time will tell but nam coming in a tad stronger on this run

NAM coming in much further north. It’s a catch-22 though as we have mixing issues closely by.

Had a feeling we’d see a north bump. Now we just don’t want too far north lol!

NAM is also faster. Just after lunch time on Friday. High res version is also further both but rather anemic looking.

NBM favors the tri-state.

For max accumulation potential, we don’t want this to speed up. If it falls primarily during the day, accumulation will be harder to achieve.

The boys had this to say:

Short wave emerging out of the central Plains will track east
southeast across Kentucky on Friday. This will result in a slowly
strengthening surface low passing well south of the forecast area.
There will be a shield of precipitation north of the low, although
how far north that extends is still a bit uncertain.

All guidance is showing a weak frontogenetic band spreading across
northern counties after midday. The bigger question is south. 12Z
guidance has been showing a corridor of low level dry air near the
Ohio River which will take some time to saturate with the NAM
consistently indicating that forcing will have passed by the time
saturation occurs. Given this, have continued to limit PoPS to
likely. Non-NAM model QPF has come down, looking a bit more
reasonable which is translating into lower potential snow amounts.
Forecast now has less than an inch areawide. With part of this
occurring during the day, and possibly mixing with rain across far
southern counties, road impacts will likely be limited, but cannot
rule out some issues after dark until precipitation pulls out by
late evening

A low slowly strengthening along the KY / TN border is an ideal track for Cincinnati. 18Z NAM has 0.27". 18Z RGEM has 1-3" across the area. Slower moving system and the later arrival after 4 or 5pm Fri.

18Z ICON has 2" for most posters minus SE Counties. 3" to iso 4" possible.

18Z GFS is coming back north too.

tron777 wrote: ↑Wed Feb 14, 2024 4:46 pm 18Z GFS is coming back north too.

I agree Les and maybe just maybe the CMC/RGEM will be the best model. Not saying it did great last time but if it were a baseball game the model got a single where the GFS and Euro struck out on 3 pitches and never took a swing

18Z GFS is still faster at bringing in the snow. I think it's a bit too fast mainly due to dry air concerns. Heaviest snow is still either side of I-64 in KY. QPF is 0.16" at CVG, 2-3" south of the Metro. An inch or so for the Metro on north.

tron777 wrote: ↑Wed Feb 14, 2024 4:59 pm 18Z GFS is still faster at bringing in the snow. I think it's a bit too fast mainly due to dry air concerns. Heaviest snow is still either side of I-64 in KY. QPF is 0.16" at CVG, 2-3" south of the Metro. An inch or so for the Metro on north.

That is a concern of mine and part of that is with the first system overnight and Thursday. Behind that system you tend to get a surge of drier air but how much is a question we need to answer. Many time two storms that close together can hurt the second system. Hopefully by this time on Thursday we have a better ideal of how much dry air will need to be overcome

After Reading ILNs FA Les posted , I think they dozed off in mid write-up