Absolute Vorticity

tpweather wrote: ↑Mon Dec 04, 2023 5:23 am Good Morning and a normal first full week of December though temps will rise late in the week. Storm system for the weekend is coming around the way all on this forum saw and that is some hopefully decent rains that may end as a bit of snow but nothing to write home about. We are in a pattern that does not give us many chances for snow. What I want to see is how strong this system is before heading into Canada. For several months storms have not got as strong or wet as models showed several days in advance. This storm does have that dip in the jet and maybe enough to help as we do get into the upper 50's and maybe low 60's ahead of the system. Again most on here saw very little until at least the last 10 days of the month and that still seems correct.

Great point there Tim! Is this going to end up being a weak piece of junk, or is the stronger Euro actually on to something? We should know that answer in about another 72 hours give or take.

Bgoney wrote: ↑Mon Dec 04, 2023 7:51 am Since August CVG is a whopping 5.22” below normal precipitation

Ouch! Hopefully, we can make it up once the STJ wakes up, assuming it does.

12z GFS is weird on this run, tracks the Low from TX panhandle, to OKC, to Columbus, MO then St Louis, then it seems to retrograde South to Evansville/Terre Haute, then it moves to Indy and then Ft Wayne and then into the thumb of Michigan, for us to still get a whopping 0.3"

Uhh...

Nothing surprising in the weekly ENSO update. Nearing peak when it’s supposed to.

SEPT-OCT-NOV ONI is in also , at + 1.8c

12z Euro coming in loaded with rainfall amounts.

While those amounts are likely too high, I like a blend of the GFS and Euro re: track. Track through central IN into MI.

Trev it looks like what I am seeing is the blocking to the northeast with the Euro having the strongest and that in turn slows down the system. The Gfs is the fastest with the CMC somewhere in between but closer to the Euro

Good evening all! Sorry for the lack of posts. It's been a busy day! Finished my Christmas Shopping after work and met the folks for dinner at Longhorn.

Anyway... We have some rain coming tomorrow which could end as some flakes Tues evening. A cold Wed with highs in the U30s to L40s across the region then we warm up again ahead of our weekend system. I like the ILL or Central IN track as well. Rain, wind, maybe a few t-storms ending as a bit of snow looks like a good call to me. The timing can be tweaked when we get closer, but late Fri night thru Sun night looks to be a good window for this particular storm system. At this time, I do not think that any snow on the backside of this system will cause us any issues. That should be well to our north and west if we have the track of the surface low nailed down of course.

00z GFS coming in strong. Beginning to consider a possible severe threat up this way (marginal most likely). Low CAPE/high shear as is typical this time of year. 850mb winds will be screaming so a low-topped line of convection may be able to tap into that and produce damaging winds gusts.

I also think we will hit wind advisory criteria late Sunday. Probably will see an advisory issued.

The Euro has come back to reality with precip totals now showing an inch plus versus a few inches.

Good morning! I think up to 1" is possible especially with a stronger low. The track and timing will be critical for any severe risk as well as backside snow showers. The Euro takes the trough even more negatively titled then the GFS! It definitely has wind machine written all over it. We are on the same page there Trev if the low comes in as strong as depicted. I will continue the call I made last night of rain late Fri night / Sat then it changes to snow late Sun / Sun evening at the very end. The frontal passages looks to be Sun morning so not the best timing for severe however the dynamics should more then make up for it again if the low is that strong and if the trough goes negative tilt.

In the short term, a band of light rain over IN is heading in our direction. Could begin as some sleet then rain locally, but the best chance of any wintry precip will be in the north. Same this evening as the system wraps up. A chilly day today with temps in the mid 30s right now only getting up to around 40-42 degree range. Probably will stay in the 30s for our northern counties.

Good Morning and pretty close to my favorite hourly report and that is 38 and rain. All I need is for it to be windy and its perfect lol. Why would this be perfect because over the years it seem 38 rain and windy is telling me we are getting closer to a switch to winter like weather. Of course this time any major winter weather is still a ways off but it gives me hope.

Les has got the forecast down and nothing much to add expect lets talk about the Euro for just a minute. The Euro is known for holding back storms in the 4 corners area and my guess it has something to do with the mountains out west but that is only a guess. The Euro once again was keeping the storm back but only a few runs before it really did a 180 and sent the storm to far east. That was a little unusual for the model and my guess it was still holding on to a -NAO which should not be around so the blocking of systems will not be there as much and we see a nice storm but not what the Euro showed several time though today more in line with the GFS. This season I do expect several storms over the 4 corners once the STJ and polar jet get in their positions. Will the Euro continue to hold storms back or will the STJ be strong enough and close enough where the model is able to show the progression of these storms.

The system for the weekend and there is plenty of energy with this system and really one that seems to have enough going for it to make it a nice rain event for us. I agree about the wind and again storms with this kind of energy can really ramp up the winds. Severe weather comes in different forms especially in the winter season and something we have seen in recent years is a more northward trend to severe weather. Still not expecting a big outbreak locally but the winds alone can be enough to be severe for a period of time along with some heavy rain.

Turns colder behind the system for a few days but I believe we have another week of mild weather before we really begin to see changes. The models over the next several days will tend to go back and forth on the longer term with one run showing the mild weather staying longer and the next run showing the cold rushing in about 2 weeks from today. That is where you start to look around the NH and see exactly what is going on to get a better ideal of timing. I do expect a bigger storm to usher in the change but of course no way of knowing where and of course the exact date this far out. The NAO which has been mainly negative for the past several months looks to be more neutral or slightly positive the next few weeks but most models are showing that heading back to the -NAO later this month and that makes the last 1/3 of December very interesting.

tron777 wrote: ↑Mon Dec 04, 2023 4:43 am

airwolf76 wrote: ↑Mon Dec 04, 2023 2:56 am very nice to see your tree up Les. I may start doing some decorating today. its been very damp and rainy around here lately, but temps have been seasonal so thats always good. im not really anticipating any real cold or snow till later in the month and if it holds off till say mid January it wont break my heart either.

Thanks Charles!!! I am still eyeing the period near or after the 20th for some possible fun and games.

The weather has been very nice and boring around here I was able to get stuff done. i might finish today or maybe this weekend . they are saying temps will be in the upper 50s. but a washout on sunday.
we will see . things do look pretty interesting the rest of the month so we may get something or maybe Christmas week

airwolf76 wrote: ↑Tue Dec 05, 2023 8:00 am

tron777 wrote: ↑Mon Dec 04, 2023 4:43 am

airwolf76 wrote: ↑Mon Dec 04, 2023 2:56 am very nice to see your tree up Les. I may start doing some decorating today. its been very damp and rainy around here lately, but temps have been seasonal so thats always good. im not really anticipating any real cold or snow till later in the month and if it holds off till say mid January it wont break my heart either.

Thanks Charles!!! I am still eyeing the period near or after the 20th for some possible fun and games.

The weather has been very nice and boring around here I was able to get stuff done. i might finish today or maybe this weekend . they are saying temps will be in the upper 50s. but a washout on sunday.
we will see . things do look pretty interesting the rest of the month so we may get something or maybe Christmas week

Hey Charles and hope all is well. We had a great fall in terms of getting stuff done. Had a really nice fall color this year thanks to some cool and clear nights in September and just enough rain in October to help the color. The only item which I have seen is the bird migration this season and its different around my house as the birds have been few and far between. I know other folks on here have seen an uptick. Saying that I did see a flock yesterday and maybe they are heading for my house as tons of berries on the trees and they love to have a nice snack for a 3-5 period normally

Good posts this morning fellas! I think we are all generally on the same page here with the weekend system and the extended range.

There have been a few flakes mixing in from time to time around the Dayton area, but mostly a light rain.

dce wrote: ↑Tue Dec 05, 2023 8:20 am There have been a few flakes mixing in from time to time around the Dayton area, but mostly a light rain.

Same here on the south side. Mostly rain but a few snowflakes hitting the windshield while driving. Temp is 35. Looking forward to finally some active weather. Beginning to fall asleep over here.

Currently 34 here in G'ville and progged for around 41 today.

Nice upset win in OT by the Bengals over the postseason-heading Jaguars!

Siberia getting cold and nothing new for early December but like I mentioned before they have been back and forth during November and really somewhat later than normal. I saw a great forecast for some city in Siberia where yesterday they had a sunny sky with an low of -66 and a high of -64. Bgoney had shown the the PV had gotten itself together and yes this is what happens when that occurs. I thought we really needed a period of very cold around the poles because you need that really deep cold in the longer term if we can disrupt the PV and have cold air drain southward. We have seen spokes over the past month and they have been cold but narrow in nature. Would love to see more build up of snow northwest of us over the next two weeks in case we get a colder air mass to head this way. Alaska at the moment is seasonally cold and really only saw one quick shot of really cold air this fall season though snow in the southern part of the state has been heavier than normal. Still have the cold in eastern Europe and some of that did spread to western Europe over the past several days though folks in Spain and southern Italy and Greece seem to have the cold stay north of them for the most part. Northern Canada is seasonally cold as well and has been most of this fall season.

Just a few visuals to add to Tim’s great info on the temps world wide and where they might be headed . Only comment I would add is that the 500mb forecast for the foreseeable future is about as hostile as it can get for snow lovers in the lower 48 (except for lakes region and mountains) and Canadian prairie

The above images continue to show a +EPO. Even with a +PNA and / or -NAO, those ridges just act to keep whatever pattern we have going, continue. We need the PNA ridge to poke up into Alaska and the North Pole to dislodge the cold from Siberia and send it southward. Having a better looking Pacific pattern means so much more then anything else that we talk about.

Monthly EPO index data can be found here:

https://psl.noaa.gov/data/correlation/epo.data

Oct: 0.31
Nov: 0.39

December may likely avg the same. Hopefully we see those changes around Christmastime that continue to show up on the longer term guidance. MJO is currently in Phase 4 as of 12/3. Hopefully we can get it to the colder phases in a few weeks. The latest modeling I have seen from today shows it weakening in mid December and struggling to get to where we want it to be. My guess is that the West Pacific warm pool could be interfering with the wave propagation. Strange but we had a bad Pacific last December in a La Nina and we currently have a bad Pacific with an El Nino too. It is only 12/5 but at the same time, we need to see the improvements occur late Dec into early January or even I will become concerned.

Concerning the system this weekend and not expecting to many changes though the system will not be into the USA until Thursday. The really only question I have is the NAO and will we have any blocking to help slow down the system. System has energy and may be the strongest we have seen come into the pacific this fall season. So yes I am sure some minor changes to the track but from what I see this will probably be minor locally but folks to the west it could be the difference between a decent rain or some decent snows.

12z GFS continues to show a setup that could produce strong non-thunderstorm winds and also strong to severe thunderstorm winds. Timing is a bit late so that may help keep it confined to isolated severe here. But yes I do think our wind threat is increasing.

GFS matches the Euro with an inch or so of rain.

Unlike previous systems this one is strengthening so it will really be able to pull in a lot of moisture from the GOM. I’m not worried about totals drying up as we get closer versus if it were a weaker system.

Trevor wrote: ↑Tue Dec 05, 2023 11:36 am GFS matches the Euro with an inch or so of rain.

Unlike previous systems this one is strengthening so it will really be able to pull in a lot of moisture from the GOM. I’m not worried about totals drying up as we get closer versus if it were a weaker system.

Trev this is key to winter storms and one that is strengthening vs one weakening. Sure sometimes this hurts us in terms of snowfall as a certain cuts back to far west but getting a stronger to strength near us or just east is good in terms of precip. I believe this system also has plenty of energy and I always look at storms coming in from the pacific to see moisture content but sometimes more important is the wind and the is a part of the energy that gets underestimated imo.

Sunday has a chance to be a day we start out mild at midnight with rain but the front comes and we drop 20 degrees with some snow flurries late in the day. Sounds like a good day to watch football