Absolute Vorticity

Les I hope that is true about the snow cover out west. Still looking at early Wednesday morning as we have some moisture around though limited it could bring a period of frz/drizzle. This is nothing major but as we know getting decent cold air from the ground to move out can take a little longer than models show. This won't last long but its timing. If the precip holds off until later morning or early afternoon then just some light drz/rain will fall. The air may be too dry and the forcing is well to the north but I must added it to my forecast just because I have seen this play out many times over the years.

tpweather wrote: ↑Mon Dec 02, 2024 9:18 am Les I hope that is true about the snow cover out west. Still looking at early Wednesday morning as we have some moisture around though limited it could bring a period of frz/drizzle. This is nothing major but as we know getting decent cold air from the ground to move out can take a little longer than models show. This won't last long but its timing. If the precip holds off until later morning or early afternoon then just some light drz/rain will fall. The air may be too dry and the forcing is well to the north but I must added it to my forecast just because I have seen this play out many times over the years.

I've been going with Wed afternoon for the timing for the last few days so I will stick with that idea. If correct, it would just be plain old rain. No matter what ends up happening, the precip amounts are very light anyway so as you said Tim, a non event still looks to be in the cards most likely anyway.

Kind of funny that nearly the same amount of qpf ( couple hundredths) is expected in a scattered fashion for there same (ILN) FA later today, that they continued to have an advisory for over the weekend

That little disturbance looks kind of healthy at the moment. Maybe some areas in Illinois, Indiana, and Kentucky see more than a dusting out of this? Maybe 1-2 inches if that holds together?

Hrrr is within it’s usefull range, and steadily trending with more Qpf mentioned earlier in a scattered fashion along the river , a couple hundredths

Bgoney wrote: ↑Mon Dec 02, 2024 11:07 am Hrrr is within it’s usefull range, and steadily trending with more Qpf mentioned earlier in a scattered fashion along the river , a couple hundredths

We'll take what we can get, but I was always under the impression that this system would have even less QPF then the last one.

tron777 wrote: ↑Mon Dec 02, 2024 11:14 am

Bgoney wrote: ↑Mon Dec 02, 2024 11:07 am Hrrr is within it’s usefull range, and steadily trending with more Qpf mentioned earlier in a scattered fashion along the river , a couple hundredths

We'll take what we can get, but I was always under the impression that this system would have even less QPF then the last one.

Yea , it’s still just something that can bring a smile for those that see flakes flying along with the cold temps

Bgoney wrote: ↑Mon Dec 02, 2024 11:26 am

tron777 wrote: ↑Mon Dec 02, 2024 11:14 am

Bgoney wrote: ↑Mon Dec 02, 2024 11:07 am Hrrr is within it’s usefull range, and steadily trending with more Qpf mentioned earlier in a scattered fashion along the river , a couple hundredths

We'll take what we can get, but I was always under the impression that this system would have even less QPF then the last one.

Yea , it’s still just something that can bring a smile for those that see flakes flying along with the cold temps

Radar looks good for the call too. You can see the better returns over S ILL which will impact the Western part of KY. That is where you could get that 1" in my mind. The flurry call for us looks great!

If you watched Brain's video today.... he mentioned a lot of rain to snow set up's in the extended range. For now, I also agree and think that is the way to go. The strength of the SE ridge as well as the timing of each shortwave will tell us the precip type that we can expect once we get closer to each system. What we need in this set up is to get a rain to snow situation then have a piece of follow up energy quickly on its heels for an all snow set up after that. This is a very common set up for our area and it is one that we should see for the next 2-3 weeks.

tron777 wrote: ↑Mon Dec 02, 2024 12:38 pm If you watched Brain's video today.... he mentioned a lot of rain to snow set up's in the extended range. For now, I also agree and think that is the way to go. The strength of the SE ridge as well as the timing of each shortwave will tell us the precip type that we can expect once we get closer to each system. What we need in this set up is to get a rain to snow situation then have a piece of follow up energy quickly on its heels for an all snow set up after that. This is a very common set up for our area and it is one that we should see for the next 2-3 weeks.

I did watch Brian's video and the one item which caught my attention is how he has a graph showing the pna going negative. The last one I saw from the NWS was a healthy positive to slightly by mid-month while he shows it going rather negative. That is a big difference in the longer term. Yes I still believe its going to get milder mid-month but he has it coming in quicker. I agree has he mentioned the arctic needs to reload and the PV should get stronger for this to happen and his map showed Siberia really getting cold which makes sense because they have been so mild compare to normal.

tpweather wrote: ↑Mon Dec 02, 2024 1:11 pm

tron777 wrote: ↑Mon Dec 02, 2024 12:38 pm If you watched Brain's video today.... he mentioned a lot of rain to snow set up's in the extended range. For now, I also agree and think that is the way to go. The strength of the SE ridge as well as the timing of each shortwave will tell us the precip type that we can expect once we get closer to each system. What we need in this set up is to get a rain to snow situation then have a piece of follow up energy quickly on its heels for an all snow set up after that. This is a very common set up for our area and it is one that we should see for the next 2-3 weeks.

I did watch Brian's video and the one item which caught my attention is how he has a graph showing the pna going negative. The last one I saw from the NWS was a healthy positive to slightly by mid-month while he shows it going rather negative. That is a big difference in the longer term. Yes I still believe its going to get milder mid-month but he has it coming in quicker. I agree has he mentioned the arctic needs to reload and the PV should get stronger for this to happen and his map showed Siberia really getting cold which makes sense because they have been so mild compare to normal.

Hey Tim.... my thoughts on the differences that you are seeing in the PNA index is that Brian showed the PNA index forecast from the Euro Ensembles, where if you go to the CPC's website, that is usually taken from the GFS Ensembles and that is the forecast that you have described in your post.

tron777 wrote: ↑Mon Dec 02, 2024 1:17 pm

tpweather wrote: ↑Mon Dec 02, 2024 1:11 pm

tron777 wrote: ↑Mon Dec 02, 2024 12:38 pm If you watched Brain's video today.... he mentioned a lot of rain to snow set up's in the extended range. For now, I also agree and think that is the way to go. The strength of the SE ridge as well as the timing of each shortwave will tell us the precip type that we can expect once we get closer to each system. What we need in this set up is to get a rain to snow situation then have a piece of follow up energy quickly on its heels for an all snow set up after that. This is a very common set up for our area and it is one that we should see for the next 2-3 weeks.

I did watch Brian's video and the one item which caught my attention is how he has a graph showing the pna going negative. The last one I saw from the NWS was a healthy positive to slightly by mid-month while he shows it going rather negative. That is a big difference in the longer term. Yes I still believe its going to get milder mid-month but he has it coming in quicker. I agree has he mentioned the arctic needs to reload and the PV should get stronger for this to happen and his map showed Siberia really getting cold which makes sense because they have been so mild compare to normal.

Hey Tim.... my thoughts on the differences that you are seeing in the PNA index is that Brian showed the PNA index forecast from the Euro Ensembles, where if you go to the CPC's website, that is usually taken from the GFS Ensembles and that is the forecast that you have described in your post.

Thanks Les and that explains the difference.

Looking at the Accuracy of Phone Weather Apps in class today - found this interesting


https://www.forecastadvisor.com

BookNerdCarp wrote: ↑Mon Dec 02, 2024 2:27 pm Looking at the Accuracy of Phone Weather Apps in class today - found this interesting


https://www.forecastadvisor.com

What’s amusing about this is October was about as boring and uneventful for a large part of of the country as you can get. The company’s with low scores must be using horses and goats to help with the forecast

Love to know what information they used for these results.. I agree Oct was easy and love to see the Nov results

I do like the Indy NWS notes always. Talking about the 8-14 day period and things are out of whack so they are not sure which way to go and I agree there are things that add up to a milder period but how mild and how wet is something we need to figure out in the next few days.

tpweather wrote: ↑Mon Dec 02, 2024 3:03 pm Love to know what information they used for these results.. I agree Oct was easy and love to see the Nov results

Even us humans had a 90+% accuracy rate for October. When you are in a drought (stable pattern) forecasting is easy! I'd like to see those results after the upcoming winter is over.

Flurries and snow showers are moving in.... SPS from the boys:

...SLICK ROADWAYS POSSIBLE THROUGH THIS EVENING...

Snow showers will begin to move across the area and continue into
the early overnight hours, impacting the evening commute. While
accumulations will be light, air temperatures will drop below
freezing, resulting in the potential for some slick spots,
especially on bridges and overpasses. Slippery roadways will
linger overnight even after the snow ends given the cold pavement
temperatures.

Motorists should exercise extra caution through the evening and
overnight hours. What appears to be wet roads may actually be
patches of ice, particularly if you drive over a bridge. Slow down
and allow extra distance between you and other vehicles.

Not all of this is reaching the ground

Bgoney wrote: ↑Mon Dec 02, 2024 4:59 pm Not all of this is reaching the ground



IMG_2728.gif

30 / 18 IMBY - Still virga.

Just came through Versailes Indiana. It was snowing pretty good there

I've been seeing some flurries now too over the last 1/2 hour.

tron777 wrote: ↑Mon Dec 02, 2024 6:26 pm I've been seeing some flurries now too over the last 1/2 hour.

Still no flurries here but hopefully a few in the next couple of hours before its out of here