Absolute Vorticity

Trevor wrote: ↑Mon Nov 27, 2023 10:46 am Tim you are absolutely correct re: moisture-robbing southern convection. Attached is the 00Z Euro and you can see how the south gets very heavy rainfall totals and lesser amounts up this way. I expect that to be the case.

Hey Trev, and I hope this is not the trend this winter. Nothing worse then having a great setup for snow and the storms to the south rob this area of moisture. Another point with the STJ being very active that some storms may start out nice in the central and southern plains and head this way only to transfer energy to the Carolina coast where more energy may be located. Again not even into December and many things can happen but no doubt something that I will watching for in terms of trends.

tpweather wrote: ↑Mon Nov 27, 2023 11:04 am

Trevor wrote: ↑Mon Nov 27, 2023 10:46 am Tim you are absolutely correct re: moisture-robbing southern convection. Attached is the 00Z Euro and you can see how the south gets very heavy rainfall totals and lesser amounts up this way. I expect that to be the case.

Hey Trev, and I hope this is not the trend this winter. Nothing worse then having a great setup for snow and the storms to the south rob this area of moisture. Another point with the STJ being very active that some storms may start out nice in the central and southern plains and head this way only to transfer energy to the Carolina coast where more energy may be located. Again not even into December and many things can happen but no doubt something that I will watching for in terms of trends.

With an active southern branch, there will no doubt be multiple occasions where there is a severe thunderstorm event to the south that does impede moisture flow to the north. Being in an El Niño pattern would lead me to believe that it will happen more than usual this winter. But in the end, there is always a lot of severe weather in Dixie Alley every winter as that is their severe weather season.

12z GFS gives us an inch on Friday then has the Sunday system way south with only scattered precip Sunday. More of a phase with a second system for late Monday that gives us another shot at some rain.

tron777 wrote: ↑Mon Nov 27, 2023 10:34 am Tim CB is talking about going into phase 8 and 1 after mid month. You could see it on the Gefs extended mjo plot which is available on the CPCs website. I will check the other mjo modeling this evening.

Thanks Les and went back to his site and though the graph shows heading to phase 8 and 1 after mid-dec he wrote that is was going to be in those phases in the second week of December. That is where the confusion is and thought I read his thoughts correctly

tpweather wrote: ↑Mon Nov 27, 2023 1:33 pm

tron777 wrote: ↑Mon Nov 27, 2023 10:34 am Tim CB is talking about going into phase 8 and 1 after mid month. You could see it on the Gefs extended mjo plot which is available on the CPCs website. I will check the other mjo modeling this evening.

Thanks Les and went back to his site and though the graph shows heading to phase 8 and 1 after mid-dec he wrote that is was going to be in those phases in the second week of December. That is where the confusion is and thought I read his thoughts correctly

Tim... I am sure you know this, but just as a reminder to anyone who may not know, CB likes to hype things up to keep folks clicking on his blog. We call it "click bait" these days if you know what I mean. BG tells it like it is just like we do on this forum. Sure I get excited a lot. Who doesn't it? I maybe wrong sometimes. Again, who isn't? I need to look over the guidance and I'll make a post on what I think here soon.

Trevor wrote: ↑Mon Nov 27, 2023 1:10 pm 12z GFS gives us an inch on Friday then has the Sunday system way south with only scattered precip Sunday. More of a phase with a second system for late Monday that gives us another shot at some rain.

Yeah... it looks like most of the globals have trended in this direction today. Man... it is going to be a long winter!

tron777 wrote: ↑Mon Nov 27, 2023 5:24 pm

Trevor wrote: ↑Mon Nov 27, 2023 1:10 pm 12z GFS gives us an inch on Friday then has the Sunday system way south with only scattered precip Sunday. More of a phase with a second system for late Monday that gives us another shot at some rain.

Yeah... it looks like most of the globals have trended in this direction today. Man... it is going to be a long winter!

Definitely more reason to use an even more conservative forecasting approach than usual re: any potential snow setups this winter, especially outside of 24-36hrs.

No doubt Trev, no doubt which leads me to the following post. The longer term does not look as good for colder weather as it did over the Thanksgiving Holiday. I still think that we could have a snow chance around Dec 7-8th from a possible digging clipper, otherwise, that is all I see currently for the 1st half of December. It's basically a thread the needle type of pattern which we rarely do well in.


The Euro Weeklies still look good for cold and snow lovers from near Christmas and also well into January. But for December... we may need to wait until the second half of the month for better snow chances. I probably jumped the gun the other day when I said after Dec 10th. So I apologize to you all for doing that. I was the only one who did so who forecast on this forum. Still though, I do not see a historic torch like last year if it's any consolation.

tron777 wrote: ↑Mon Nov 27, 2023 6:21 pm No doubt Trev, no doubt which leads me to the following post. The longer term does not look as good for colder weather as it did over the Thanksgiving Holiday. I still think that we could have a snow chance around Dec 7-8th from a possible digging clipper, otherwise, that is all I see currently for the 1st half of December. It's basically a thread the needle type of pattern which we rarely do well in.


The Euro Weeklies still look good for cold and snow lovers from near Christmas and also well into January. But for December... we may need to wait until the second half of the month for better snow chances. I probably jumped the gun the other day when I said after Dec 10th. So I apologize to you all for doing that. I was the only one who did so who forecast on this forum. Still though, I do not see a historic torch like last year if it's any consolation.

Great Post Les. The Dec 7-8th clipper is showing some promise and the reason you mentioned more digging plus with the STJ active it would not take much to have the clipper combine with moisture from the GOM. Tell you the truth Les the period you mentioned before the 15th is colder than I thought would happen. No doubt the torch will not be out this December and though some days in the 50's and maybe a 60 ahead of a front but again today in the mid 30's and that is a good 10 plus degrees below normal. The Euro weeklies to show some snow and cold is a good sign as we are getting to the time of year where we tend to trust the Euro. I do believe the Euro is warmer after the 7th or 8th and I do believe that as well. This current cold snap is rather impressive imo as the cold to start in Canada not the coldest ever and little snow in the northern plains however Eastern Canada has got off to a very cold and snowy start and if the cold hangs out there we could see some back door cold fronts that move into our area and have a nice you fight with the STJ to our south. Do I get excited this time of year and no doubt and especially after last winter except for the period just before Christmas. So many times in December over the past decade or two winter starts late around here and sort of made sense with summer time warmth that lasted well into Sept and Oct. This fall though we had tons of clear cool nights in September and it seemed like a longer fall period and maybe with the earlier start to fall we are going to see some true winter weather in December.

I’m still going with near to slightly above normal temps for an average the first half of Dec due to all the troughyness in the pacnwest

Bgoney wrote: ↑Mon Nov 27, 2023 7:15 pm I’m still going with near to slightly above normal temps for an average the first half of Dec due to all the troughyness in the pacnwest

Same here Bgoney and that has not changed at all. Even late this week and weekend look mild. I do believe the period from the about the 5th-9th could be slightly below normal but I do expect a surge of milder air that could help in getting the clipper system models are starting to show around the 7th or 8th a little more bite and if we are in the correct place some snow could fall. Then after that I do expect a mild period through at least the 15th and most likely the 20th before I see a major pattern change.

tpweather wrote: ↑Mon Nov 27, 2023 7:40 pm

Bgoney wrote: ↑Mon Nov 27, 2023 7:15 pm I’m still going with near to slightly above normal temps for an average the first half of Dec due to all the troughyness in the pacnwest

Same here Bgoney and that has not changed at all. Even late this week and weekend look mild. I do believe the period from the about the 5th-9th could be slightly below normal but I do expect a surge of milder air that could help in getting the clipper system models are starting to show around the 7th or 8th a little more bite and if we are in the correct place some snow could fall. Then after that I do expect a mild period through at least the 15th and most likely the 20th before I see a major pattern change.

I agree with you both. A few colder days mixed in as Tim is mentioning but it should still avg above normal overall. We'll see what happens around the 7-8th as time goes on.

I found this posted on another forum which I thought was interesting. I am quoting the post since I didn't write it.

Here is an MJO product that combines the standard MJO with the current 120-day signal (i.e. the background base tropical forcing pattern). This product has the MJO running thru 8-1-2 from Dec 15 to Jan 10. Euro Weeklies look similar.

Source: https://ncics.org/portfolio/monitor/mjo/RMM/

That would be pretty awesome if the MJO actually performed as shown. We shall see!

tron777 wrote: ↑Mon Nov 27, 2023 7:52 pm I found this posted on another forum which I thought was interesting. I am quoting the post since I didn't write it.

Here is an MJO product that combines the standard MJO with the current 120-day signal (i.e. the background base tropical forcing pattern). This product has the MJO running thru 8-1-2 from Dec 15 to Jan 10. Euro Weeklies look similar.

Source: https://ncics.org/portfolio/monitor/mjo/RMM/

Nov-27-CFS-MJO-Lowpass.png


That would be pretty awesome if the MJO actually performed as shown. We shall see!

Les that would be dream come true. A rather strong phase as well plus once it gets into phase 2 at the end it looks like its trying to curve back around and stay out of the warm phases.

tpweather wrote: ↑Mon Nov 27, 2023 7:57 pm

tron777 wrote: ↑Mon Nov 27, 2023 7:52 pm I found this posted on another forum which I thought was interesting. I am quoting the post since I didn't write it.

Here is an MJO product that combines the standard MJO with the current 120-day signal (i.e. the background base tropical forcing pattern). This product has the MJO running thru 8-1-2 from Dec 15 to Jan 10. Euro Weeklies look similar.

Source: https://ncics.org/portfolio/monitor/mjo/RMM/

Nov-27-CFS-MJO-Lowpass.png


That would be pretty awesome if the MJO actually performed as shown. We shall see!

Les that would be dream come true. A rather strong phase as well plus once it gets into phase 2 at the end it looks like its trying to curve back around and stay out of the warm phases.

That has been the expectation with regards to the MJO phases in Jan and Feb. Keep looping back thru Phases 7 thru 2 due to the tropical forcing remaining near / West of the Dateline. Don't know if that will happen but that's the call anyway.

tron777 wrote: ↑Mon Nov 27, 2023 7:52 pm I found this posted on another forum which I thought was interesting. I am quoting the post since I didn't write it.

Here is an MJO product that combines the standard MJO with the current 120-day signal (i.e. the background base tropical forcing pattern). This product has the MJO running thru 8-1-2 from Dec 15 to Jan 10. Euro Weeklies look similar.

Source: https://ncics.org/portfolio/monitor/mjo/RMM/

Nov-27-CFS-MJO-Lowpass.png


That would be pretty awesome if the MJO actually performed as shown. We shall see!

CFS along with the BOMM’rs are amped up with their forecast, but most are heading for a similar outcome albeit slower and less amped. FWIW , on that diagram the November location and amplitude are way off

Good Morning and nice crisp late November morning and may see a few flurries early today. Of course this time of year we have many items going on which will try and set the stage for at least part of the winter. One item we talked is the Polar Vortex. How strong is it at the moment compared to what some folks mention. I say this because the current weather is helped but a spoke of the PV in eastern Canada. We keep seeing this show up as well on forecasts further out in December. The AO is still negative and expected to get near neutral but not seeing any forecasts of a positive AO. This has me looking around the polar regions and really for late November not that cold with the lowest temps in the -30 - -40 range. Usually but not every year temps are nearing the -50 range in Siberia with -60 - 80 once we get into December. That would be with a strong PV and my guess a positive AO. The cold has been in eastern Canada and parts of eastern Europe but not at the poles but lower in latitude. So are seeing a winter season where the PV is not that strong and much easier to disturb whether it be from a SSW event or the spokes of the PV are able to move more freely like we see at the moment.

Bgoney wrote: ↑Tue Nov 28, 2023 5:21 am

tron777 wrote: ↑Mon Nov 27, 2023 7:52 pm I found this posted on another forum which I thought was interesting. I am quoting the post since I didn't write it.

Here is an MJO product that combines the standard MJO with the current 120-day signal (i.e. the background base tropical forcing pattern). This product has the MJO running thru 8-1-2 from Dec 15 to Jan 10. Euro Weeklies look similar.

Source: https://ncics.org/portfolio/monitor/mjo/RMM/

Nov-27-CFS-MJO-Lowpass.png


That would be pretty awesome if the MJO actually performed as shown. We shall see!

CFS along with the BOMM’rs are amped up with their forecast, but most are heading for a similar outcome albeit slower and less amped. FWIW , on that diagram the November location and amplitude are way off




IMG_0898.gif

This is the first time that I have seen that product so my assumption is that it is probably experimental unlike the normal MJO plots that we see on the CPC's website on a daily basis.

The 12z Euro has a system on Monday and then again on Tuesday of next week diving into our region producing some light snow. The CMC and GFS do not have these 2 systems.

dce wrote: ↑Tue Nov 28, 2023 2:58 pm The 12z Euro has a system on Monday and then again on Tuesday of next week diving into our region producing some light snow. The CMC and GFS do not have these 2 systems.

Hey Doug and after the system on Friday I believe we may see a clipper or two the following week. I had more towards the 7th but again can we get one to hook up somewhat to the STJ as warmth will be building in the central USA. Not sure yet and still I believe the pattern is there for a smaller system but will the warm air be to fast or moisture not fast enough from the GOM to bring a wetter system. I do after that though we truly have a nice mild period for a week to 10 days as thing realign the NH.

Thurs night and Friday looks like a pretty wet period that all models are agreeing upon. After that... who knows! The models are really struggling to figure out what happens next. Is it a clipper? Will the timing be correct for a phasing system? Is it a rain maker via the STJ? Anything goes at this point. What's funny is that the clipper idea esp around the 7-8th as Tim and I have mentioned, was agreed upon by most of the global models the other day. Now, as Doug mentioned the Euro tries to throw us a bone but the other globals do not.

I checked the Ensemble guidance to try and sort out the model noise and even the Ensemble members are all over the place. After the Thurs night and Fri rain maker I have very low confidence on what happens next week. Very low. I am going to keep an eye out for the clipper scenario though as I think that is still possible because the global models were doing a great job showing the idea until today. If it's going to happen we should see it come back in another couple of days or so. If it does not, then it was BS to begin with.

tron777 wrote: ↑Tue Nov 28, 2023 4:45 pm Thurs night and Friday looks like a pretty wet period that all models are agreeing upon. After that... who knows! The models are really struggling to figure out what happens next. Is it a clipper? Will the timing be correct for a phasing system? Is it a rain maker via the STJ? Anything goes at this point. What's funny is that the clipper idea esp around the 7-8th as Tim and I have mentioned, was agreed upon by most of the global models the other day. Now, as Doug mentioned the Euro tries to throw us a bone but the other globals do not.

I checked the Ensemble guidance to try and sort out the model noise and even the Ensemble members are all over the place. After the Thurs night and Fri rain maker I have very low confidence on what happens next week. Very low. I am going to keep an eye out for the clipper scenario though as I think that is still possible because the global models were doing a great job showing the idea until today. If it's going to happen we should see it come back in another couple of days or so. If it does not, then it was BS to begin with.

Hey Les I believe there is something there but timing is key and I believe after the 7th or 8th a nice warming trend is going to be underway. The gfs keeps giving us glancing blows of cold air after that date but I am not sold on that. Even this weekend the temps should be above normal and then do we see a cold front send some colder air this way next week. Still once again the northeast should be in the prime spot for the cold and this trend is one that may continue quite often this winter. Sure is nice to see snow buildup in eastern Canada but then we must rely on a rather -NAO to get the cold backed into our area. During the milder period that I expect from around the 8th or 9th through maybe the 21st or 22nd will we see some snow build up in the northern and central plains. We still need snow in those areas because when we get these warmer periods they can overachieve if little to any snow on the ground in those areas. STJ seems to be doing well at the moment but even the jet needs to recoup several times during the winter. Still trying to figure out if the STJ has a pathway from southern California to the east coast or does it come through Mexico and head towards Florida and then up the east coast. Big difference in precip amounts for us with either setup and maybe we get a little of both but if the southern most one plays out we may end up with many cold but dry boring days.

I agree Tim. We will have that cold shot of air around the middle portion of next week, hence the digging clipper idea then we will moderate again as you said. Makes perfect sense based on the overall pattern. What we don't know is the track of the digging wave and if there will be any moisture for it to work with. This pattern looks to be a repeating one and we should do it again around the mid December portion of the month. Hopefully sometime after that, we get the MJO in the more favorable phases as previously discussed for the Christmas period. Euro Weeklies from today still look very interesting later in December and for the first 10 days of January.

For the Friday into Saturday event for the OV triangle of Dayton,Cbus and cvgland, going with .25- .75”. Just isn’t a good flow out of the GOM at the mid level, more of a SWflow and with the trajectory of the low and how weak it is, not a big surge of moisture into the OV

Good Morning and I hit 16 this morning but up to whopping 17. May get to that 20 degree mark by sunrise. Bgoney I am lowering my rain total. This is the trend for these systems to be weaker than models show. Still believe a good push of moisture from the GOM but the speed of a weaker system should move it through quickly. I like your .25-.75 and really see no reason to go any higher. Then a brief shot of cold next week and trying to figure which day a clipper may produce our first snow though light and then I really see a nice warm up for about 10-14 days. This will not be a blow torch but my guess many days in the 50's and lows in the 30's and if we get a bigger system we could see a temp in the low 60's. Then will we see a pattern change and so far so good but we know how things can change or not change in 2 weeks