Absolute Vorticity

Posted: **Fri Feb 24, 2023 10:56 am**

The first system of interest for March could take many different forms. The OP GFS has a cold front coming in the Wed / Thurs time period of next week. Then, a strong southern wave comes in causing a possible snow storm sometime in the late Fri to early Sat range (3/3-3/4). As usual we have no cold air in place but the idea is that smaller pieces of energy eject from the Western US trough. The CMC has the energy all coming out at once so you get a stronger low and thus, a cutter. The Euro was doing the same thing until the 0Z run from last night. Now it is even more suppressed then the GFS. Due to the SE ridge I do not buy that much of a suppressed look. The Euro should correct back NW in time. How much remains to be seen. Models past 100 hours won't have any of this complex scenario correct obviously so we may not know the eventual outcome until early next week sometime. The GEFS Mean tracked the low over us and the EPS still has the Cutter scenario with the low over the Great Lakes. Typical model spread for a system that is in the Day7-8 range.

Looking further ahead... the second week of March does hold some promise for colder air getting involved with a potential for a -EPO to go along with the -NAO. We should also begin to see the SSW impacts by then. MJO still is forecast by most models to be in Phase 8 by then as well. As usual, we'll have to wait and see how things shake out. Late next week though is our first order of business for March.

Posted: **Fri Feb 24, 2023 11:23 am**

12Z GFS on this run is ejecting a bigger piece of energy out of the Western US trough. A cold heavy rain is the end result for later next week SE of I-71 then changing to heavy snow with mainly heavy snow north and west. I'll say one thing, the model has been consistent on trying to bring us a snow storm, even if it is consistently wrong.

This is like the 8th or 9th run in a row now so we should keep that one eye open look for sure.

Posted: **Fri Feb 24, 2023 11:31 am**

The 500 MB low actually briefly closes off right over us. Nice.... But we know the seasonal trends. Will this system break the curse or will it cut NW in a couple more model cycles? Stay tuned to "As the Snow Weenie Turns"

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Posted: **Fri Feb 24, 2023 11:37 am**

12Z CMC has lost the cutter idea now and is now showing a solution like the GFS minus the fact that there is no cold air and it's a big rain maker. At least the low doesn't cut, that's the important part of the run. Interesting...

Posted: **Fri Feb 24, 2023 11:57 am**

tron777 wrote: ↑Fri Feb 24, 2023 11:37 am 12Z CMC has lost the cutter idea now and is now showing a solution like the GFS minus the fact that there is no cold air and it's a big rain maker. At least the low doesn't cut, that's the important part of the run. Interesting...

Hey Les and the CMC looks like is trying to follow the Euro but not quite the shift southeast. Problem of course is lack on true arctic air and need the system itself to produce the cold plus it helps if falling at night. See if the Euro continues the same forecast from last night and my guess it will come back a tad northwest but most likely still rain. Several days to follow that system but we will take anything this winter.

Posted: **Fri Feb 24, 2023 1:13 pm**

Hey Tim... I don't have a forecast in mind yet for this system since it is so far away. Leaning towards a cold rain but you never know. March can be a wild month! 12Z GEFS Mean did shift a bit SE from the 6Z run with the low tracking from the MS River near the border of AR, TN, and MS to SKY into Eastern KY and WV. If we had cold air in place that is a nice track for heavy snow. It truly is a thread the needle situation because you have to have the right low track and you want the low to deepen as it moves well SE of you so that you're in the deformation zone. Then you can absolutely get a heavy wet snow out of it. That is what we are looking for with this system,

You can see the outcome of possibilities showing up from the GEFS members. A cutter, a snow storm, and a miss to the SE. Typical model spread this far out. To me, the key is going to be how much energy do you get out of the SW US? too much energy at once and it'll cut. Not enough and it's a miss to the SE so everything has to come together just right! We don't do complicated around here very well so while it's going to be fun to track, I am keeping my expectations in check until Tues or Wed of next week. You definitely want the front to come thru on Wed / Thurs then stall over TN / Apps so the southern low will track properly. I favor a cutter versus suppression personally. That SE ridge has been so strong and persistent and models have way underestimated it this far out only to correct NW by Day 5. That is my fear attm.

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Posted: **Fri Feb 24, 2023 1:16 pm**

Great Post Les and I agree the trend is for the southeast ridge to be the bully. Hopefully by early next week we are still talking about this system

Posted: **Fri Feb 24, 2023 1:24 pm**

tpweather wrote: ↑Fri Feb 24, 2023 1:16 pm Great Post Les and I agree the trend is for the southeast ridge to be the bully. Hopefully by early next week we are still talking about this system

I think we'll be talking about it, just hope we're not talking about flooding rainfall.

Posted: **Fri Feb 24, 2023 1:31 pm**

DT put out a new video. he sounded pretty excited for March and how the models are predicting MJO phase 8 coming. I am not sold on that yet i think we get to 7 and we have a lot of " on the fence" and " kitchen sink" type scenarios vs. pure cold and snow but thats just how I see it now. people are quick to go from one extreme to the other but I see too many things to say we need to be more apprehensive with this pattern change.

Posted: **Fri Feb 24, 2023 1:57 pm**

btw did anybody see what the GFS is showing a week from now? I must admit my heart started to flutter a bit

Posted: **Fri Feb 24, 2023 2:08 pm**

tron777 wrote: ↑Fri Feb 24, 2023 1:13 pm Hey Tim... I don't have a forecast in mind yet for this system since it is so far away. Leaning towards a cold rain but you never know. March can be a wild month! 12Z GEFS Mean did shift a bit SE from the 6Z run with the low tracking from the MS River near the border of AR, TN, and MS to SKY into Eastern KY and WV. If we had cold air in place that is a nice track for heavy snow. It truly is a thread the needle situation because you have to have the right low track and you want the low to deepen as it moves well SE of you so that you're in the deformation zone. Then you can absolutely get a heavy wet snow out of it. That is what we are looking for with this system,

You can see the outcome of possibilities showing up from the GEFS members. A cutter, a snow storm, and a miss to the SE. Typical model spread this far out. To me, the key is going to be how much energy do you get out of the SW US? too much energy at once and it'll cut. Not enough and it's a miss to the SE so everything has to come together just right! We don't do complicated around here very well so while it's going to be fun to track, I am keeping my expectations in check until Tues or Wed of next week. You definitely want the front to come thru on Wed / Thurs then stall over TN / Apps so the southern low will track properly. I favor a cutter versus suppression personally. That SE ridge has been so strong and persistent and models have way underestimated it this far out only to correct NW by Day 5. That is my fear attm.

GEFS Members.png

Alex, I'll take door #4 and #19 lol
#19 would be a nail bitter for sure and #4 would be a safe little snow fall for us!

Posted: **Fri Feb 24, 2023 2:26 pm**

airwolf76 wrote: ↑Fri Feb 24, 2023 1:31 pm DT put out a new video. he sounded pretty excited for March and how the models are predicting MJO phase 8 coming. I am not sold on that yet i think we get to 7 and we have a lot of " on the fence" and " kitchen sink" type scenarios vs. pure cold and snow but thats just how I see it now. people are quick to go from one extreme to the other but I see too many things to say we need to be more apprehensive with this pattern change.

I'm remaining skeptical myself Charles. We've got to get the -PNA to at least be more neutral and not so deeply negative as it has consistently been. That's why the SE Ridge from hell has been messing up our winter. I keep seeing the SE ridge in the Ensemble means even in early March so to me that could still be an issue. We'll just have to wait and see.

Posted: **Fri Feb 24, 2023 2:27 pm**

12Z Euro is still playing the weak / strung out card with the energy and everything is suppressed as a result. I suppose it is a possible outcome. We've seen strong lows modeled in advance crap out when we get closer.

Posted: **Fri Feb 24, 2023 2:57 pm**

12Z EPS has joined the southern track camp now. The Ensemble Mean has the low tracking from LA to northern AL to Upstate of NC. Plenty of moisture in the 0.50 to 0.75" range. The issue is of course temps. Looks like a rain maker to me ending as snow per 850 MB temps. Also this system is faster. Looks like a Thurs night into Friday kind of deal.

Posted: **Fri Feb 24, 2023 3:58 pm**

CPC just released extended outlook. Shouldn't be a surprise to anyone, we've been talking about a possible mid month cool down for a while . How much of a cool down a bit up in the air atm

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Posted: **Fri Feb 24, 2023 4:45 pm**

Great post Bgoney! Definitely seeing better MJO cooperation but not until Week 2 in March so the above map would make sense. Another reason to be skeptical of the GFS's snowy solution for the end of next week.

Posted: **Fri Feb 24, 2023 4:58 pm**

If the extended Euro is correct, we could have a very interesting mid to late March period.

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Posted: **Fri Feb 24, 2023 5:49 pm**

18Z OP GFS not backing down. It's doubling down!

Rain Thurs night and Friday changing to heavy snow Fri night and ending early Sat.

Posted: **Fri Feb 24, 2023 6:04 pm**

18Z GEFS Mean is NW back to tracking the low over us.

Posted: **Sat Feb 25, 2023 8:25 am**

Good Morning and I see CVG reported some frz/rain earlier this morning but my guess the ground was to warm to cause any problems. Should be a cool day but not horrible for late Feb. Sunday looks nice with temps getting into the upper 50's. The system late Sunday and Monday looks like another wind maker but beside that I am not seeing any severe weather. Rainfall and we know how these systems have been overdoing the rain amounts so I am going with .25-.5. Saying that we know the closer we get to spring the amount of moisture from the GOM is greater so sooner or later the amounts will be to low but this system seems to be moving quickly so going lower on the totals.

Will wait to start and figure out the remainder of the week as it will turn busy. Looking at the drought situation and the west is doing great this season and really the concern it the southern and central plains. If you want to get a hot summer that is the place it can start early and last for several months. Still time and hopefully with the jet moving further south in those areas next month we can add some rainfall but if that does not happen then watch out for the heat starting in May in those areas and most likely expanding north and east over time.

Posted: **Sat Feb 25, 2023 8:32 am**

Good morning all! The OP GFS continues to show the rain changing to a heavy wet snow situation towards the end of next week. Amazing run to run consistency from this model for sure! Is it right? It's honestly still way too early to know. CMC is now the furthest south model. Euro came back NW some but still barely misses us with the rain shield. The GEFS is still NW of the OP but the low still tracks south of us over SKY. On an Ensemble mean, the low pressure strength is in the low 990s MB. That is impressive on a mean IMO. The EPS is much weaker upper 990s to 1000 MB but it is well NW of the OP Euro showing the SKY track as well. Definitely an interesting system on our hands. ATM, we should see a spike towards 70 on Wed March 1st with a chance for showers as the cold front enters the area. The front comes thru on Thurs with another shower chance. Temps drop by Friday as the strong southern low approaches giving us rain during the day. As the low deepens, dynamic cooling takes over in the deformation zone and if the low track is right and is strong as advertised, you flip to a heavy wet snow at some point Fri afternoon thru Fri night. That is pretty much the set up should things work out as such. I will continue to monitor this like a hawk!

Posted: **Sat Feb 25, 2023 11:21 am**

12Z GFS continues the super amp'ed up low and in this case it is too strong. Track is a little too far NW. Low goes from AR to SW KY to NE KY. A cold rain with major wind transitioning to a little back end snow. Not as much snow since the low is more wound up and more warm air getting involved as a result.

Posted: **Sat Feb 25, 2023 11:50 am**

12Z CMC is still a swing and a miss. 12Z GEFS Mean is NW of the OP tracking the low from Little Rock to Paducah to our SE counties.

Posted: **Sat Feb 25, 2023 1:35 pm**

12Z Euro gets rain into our S / SE counties now so it is slowly trending towards the GFS, slowly being the key word.

Posted: **Sat Feb 25, 2023 2:32 pm**

12Z EPS continues to be well NW of the OP Euro with the low tracking from N LA thru N AL into NE TN as a 997 MB low. Then off to the east thru NC. That's a nice track with a lot of moisture too. Rain to a heavy wet snow by Fri night. Not a bad run at all. As usual, we shall see. There is still plenty of time for something to go wrong.

Absolute Vorticity

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