December 2021 Weather Discussion

[tron777]

Zonal wind anomalies are looking good right now showing a continued eastward progression of the current MJO wave. Keep on truckin'!


EPSMJO.png


EPS850wind.png

Les very important part of the puzzle. If this stalls or just dies out it may be several weeks before we get a long term cold pattern. Sure we can head towards normal but even in late December that is highs near 40 and lows in the low-mid 20's but that would be a warm up before a system and then cold behind that gives us the normal. I believe it will keep on truckin and models will show that over the next several days.

I agree Tim... we are starting to see more EPO ridging in the fantasy range too. We need to keep seeing it show up to improve confidence. the exact timing is still up in the air mind you, but sometime near or shortly after Christmas, I am liking what I am seeing attm with regards to a nice pattern change. I am starting to see the teleconnection forecasts for the NAO and AO dropping towards neutral as we get further out in time which is nice to see. That tells us the cold air is going to be on the move as long as the MJO wave doesn't crap out. I am not seeing any signs of that currently.

[young pup]

Just under half an inch here. Come on sun melt this off.

[tron777]

Finally at the freezing mark at CVG and the sun is melting the snow here. Still not much movement in shaded areas though.

[tron777]

NAM and GFS both painting an inch plus at CVG for this next event.

[cloudy72]

Just hit 32 here as well!

[tron777]

Looks like we've got an update now from CVG. 0.5" of snow total for the event so I'll update the contest thread. We're up to 0.6" now on the season. Other totals below per Local 12 News.

Snow Totals.jpg

[MVWxObserver]

Very nice coatings / dustings in assorted areas down that way for met Winter!

Too bad some of the action is partly nocturnal for the next strong to possibly severe t-storms set up for the first part of this weekend. Timetables are what they are of course.

Looks like may have to bring in the JOY display and portable lighting from the front yard due to the forecast winds for that period.

Currently at the freezing mark here in G'ville.

[tron777]

OP GFS in the fantasy range is taking on more on a -EPO and -NAO look which is good. Yes, the cold air is still dumping into the West because of the -PNA on steroids but we are slowly, and I do mean slowly beginning to see subtle changes in the extended period. Overnight EPS was showing this as well. On this afternoons GEFS run, I am also beginning to finally see these changes taking place but not nearly as pronounced as the OP GFS and EPS. It is going to be a slow process but the Christmas to New Year's period is starting to look better in my opinion. Way early to know what exactly is going to happen but I do like what I am seeing down the road a piece. We must have continued patience my friends. Until then... we've got our severe wx potential to deal with Fri night and our mega torch next week.

[tron777]

Mark J is a Met from one of the another Louisville stations I believe. Good Met IMO.

Mark J
@MJ33Wx
·
24m
Replying to
@MJ33Wx
So what is happening here? See that low out west of the Aleutians? That is going to help continue to build a north Pacific Ridge into Alaska which is a -EPO pattern. Combine that with the MJO heading into 7-8-1 to close out 2021 and bring in 2022. Cold's coming. #kywx

Check out how cold it is in Russia and you get a ridge building up towards the North Pole to promote cross polar flow... wow! If the MJO corporates early January is gonna get cold and very interesting in my honest opinion.

VodkaCold.png

[tron777]

12Z Euro (the Euro model in general) continues to have the most favorable look for severe wx Fri night. The model is stronger with the surface low so you're going to have more wind energy to play with. You get the pre frontal trough with the first round Fri late evening into the overnight then the actual line with the front itself early Sat morning. Tim... there is your two line look again my friend that you mentioned yesterday. Looks like it's got 80 knot shear right ahead of the front.

[tpweather]

Mark J is a Met from one of the another Louisville stations I believe. Good Met IMO.

Mark J
@MJ33Wx
·
24m
Replying to
@MJ33Wx
So what is happening here? See that low out west of the Aleutians? That is going to help continue to build a north Pacific Ridge into Alaska which is a -EPO pattern. Combine that with the MJO heading into 7-8-1 to close out 2021 and bring in 2022. Cold's coming. #kywx

Check out how cold it is in Russia and you get a ridge building up towards the North Pole to promote cross polar flow... wow! If the MJO corporates early January is gonna get cold and very interesting in my honest opinion.


VodkaCold.png

Great information. That storm in Alaska which sent tons of snow but much milder temps into Alaska also help push the cold air into Russia and Scandinavia over the past few days. Siberia always cold but as we know but that is some serious cold. The warmth in Alaska also has pushed into much of Canada so they are much milder than they were just a few days ago. Still cold but near to above normal in many places. With that kind of cold on the other side of the globe Mother Nature must figure out a way to balance things out. We are part of that balancing act with much warmer temps over the next week plus this time of year with that kind of warm up stronger systems are almost always going to happen. If we can get that cold to switch and head over here late in the month and much of January I would be very happy.

[tpweather]

12Z Euro (the Euro model in general) continues to have the most favorable look for severe wx Fri night. The model is stronger with the surface low so you're going to have more wind energy to play with. You get the pre frontal trough with the first round Fri late evening into the overnight then the actual line with the front itself early Sat morning. Tim... there is your two line look again my friend that you mentioned yesterday. Looks like it's got 80 knot shear right ahead of the front.

Hey Les and I believe that is the most likely outcome. So much warmth ahead of this system and to me its one getting stronger as it moves this way and it just seems to me like you mentioned a chance of the pre frontal trough helping us ignite storms later Friday and the round coming in with the front. Of course with this setup sometimes their is a place where timing is bad and you may miss out on both rounds of strong to severe weather though everyone will get wet.

[tron777]

Great information. That storm in Alaska which sent tons of snow but much milder temps into Alaska also help push the cold air into Russia and Scandinavia over the past few days. Siberia always cold but as we know but that is some serious cold. The warmth in Alaska also has pushed into much of Canada so they are much milder than they were just a few days ago. Still cold but near to above normal in many places. With that kind of cold on the other side of the globe Mother Nature must figure out a way to balance things out. We are part of that balancing act with much warmer temps over the next week plus this time of year with that kind of warm up stronger systems are almost always going to happen. If we can get that cold to switch and head over here late in the month and much of January I would be very happy.

Tim... seeing some models, like the OP GFS continuing to show a healthy Scandinavian ridge which can help get the cold to lock in forcing a -NAO to develop. The -EPO would help getting the cold from Russia into Western Canada. Since we have a -PNA to deal with the cold will initially dump over the Western US at first. But if we assume the MJO continues to move deeper into 7 and eventually Phase 8, then the cold will come to us. A lot of assumptions and as I said earlier it's going to be a slow process but hopefully near or shortly after Christmas and esp after New Year's... we can get rewarded.

[tron777]

12Z Euro (the Euro model in general) continues to have the most favorable look for severe wx Fri night. The model is stronger with the surface low so you're going to have more wind energy to play with. You get the pre frontal trough with the first round Fri late evening into the overnight then the actual line with the front itself early Sat morning. Tim... there is your two line look again my friend that you mentioned yesterday. Looks like it's got 80 knot shear right ahead of the front.

Hey Les and I believe that is the most likely outcome. So much warmth ahead of this system and to me its one getting stronger as it moves this way and it just seems to me like you mentioned a chance of the pre frontal trough helping us ignite storms later Friday and the round coming in with the front. Of course with this setup sometimes their is a place where timing is bad and you may miss out on both rounds of strong to severe weather though everyone will get wet.

As long as the Euro isn't over amping this system then this is a great call.

[cloudy72]

So normal lows this time of year are in the mid-upper 20s. How about 60+ dewpoints Saturday morning? Yowzas!

sfctd.us_state_oh.png

[tpweather]

Great information. That storm in Alaska which sent tons of snow but much milder temps into Alaska also help push the cold air into Russia and Scandinavia over the past few days. Siberia always cold but as we know but that is some serious cold. The warmth in Alaska also has pushed into much of Canada so they are much milder than they were just a few days ago. Still cold but near to above normal in many places. With that kind of cold on the other side of the globe Mother Nature must figure out a way to balance things out. We are part of that balancing act with much warmer temps over the next week plus this time of year with that kind of warm up stronger systems are almost always going to happen. If we can get that cold to switch and head over here late in the month and much of January I would be very happy.

Tim... seeing some models, like the OP GFS continuing to show a healthy Scandinavian ridge which can help get the cold to lock in forcing a -NAO to develop. The -EPO would help getting the cold from Russia into Western Canada. Since we have a -PNA to deal with the cold will initially dump over the Western US at first. But if we assume the MJO continues to move deeper into 7 and eventually Phase 8, then the cold will come to us. A lot of assumptions and as I said earlier it's going to be a slow process but hopefully near or shortly after Christmas and esp after New Year's... we can get rewarded.

Les,everything is dead on with what you mentioned. Getting the cold and hopefully snow to the west of is a key imo. Yes we have seen some cold shots this autumn but been mainly directed at us and to the east which almost always means we warm up. The one time of year is February where the cold is directed from northeast Canada into the eastern USA and that happens quite often.

[tron777]

So normal lows this time of year are in the mid-upper 20s. How about 60+ dewpoints Saturday morning? Yowzas!


sfctd.us_state_oh.png

This just isn't right. It's going to feel like spring. 60s for highs look to begin on Fri. Then start to fall after the front passes Sat. morning. 60s return for Wed and Thurs next week. Maybe even Fri, just depends on the timing of that system.

[tron777]

Great information. That storm in Alaska which sent tons of snow but much milder temps into Alaska also help push the cold air into Russia and Scandinavia over the past few days. Siberia always cold but as we know but that is some serious cold. The warmth in Alaska also has pushed into much of Canada so they are much milder than they were just a few days ago. Still cold but near to above normal in many places. With that kind of cold on the other side of the globe Mother Nature must figure out a way to balance things out. We are part of that balancing act with much warmer temps over the next week plus this time of year with that kind of warm up stronger systems are almost always going to happen. If we can get that cold to switch and head over here late in the month and much of January I would be very happy.

Tim... seeing some models, like the OP GFS continuing to show a healthy Scandinavian ridge which can help get the cold to lock in forcing a -NAO to develop. The -EPO would help getting the cold from Russia into Western Canada. Since we have a -PNA to deal with the cold will initially dump over the Western US at first. But if we assume the MJO continues to move deeper into 7 and eventually Phase 8, then the cold will come to us. A lot of assumptions and as I said earlier it's going to be a slow process but hopefully near or shortly after Christmas and esp after New Year's... we can get rewarded.

Les,everything is dead on with what you mentioned. Getting the cold and hopefully snow to the west of is a key imo. Yes we have seen some cold shots this autumn but been mainly directed at us and to the east which almost always means we warm up. The one time of year is February where the cold is directed from northeast Canada into the eastern USA and that happens quite often.

I think the thoughts we've got are good. It's just a matter of when.

[cloudy72]

Very nice writeup from the boys regarding Fri night into Saturday AM....

At this juncture, we shift our focus to Friday night into the day on
Saturday -- a setup that appears to at least somewhat concerning for
the region. There are several items to break down as we discuss the
expected evolution and potential impacts locally, so an attempt to
do so follows here:

Although we are still outside the range of many of the CAMs,
guidance continues to hone in on a climatologically-favorable track
that is /generally/ supportive of a severe threat across parts of
the OH Vly. A slowly-deepening sfc low is fcst to track from N MO to
Lake Michigan from Friday afternoon into Friday night. Deep lows on
this track have a rather long history of being supportive for at
least some severe weather across the OH Vly. And although the low
will be pulling away/N through MI by the time the FROPA actually
occurs locally around/after daybreak Saturday, it will continue to
deepen as it does so. The overall track and deepening of the sfc low
as it progresses from MO to MI puts the region squarely in a
favorable zone for robust isallobaric and LL mass field response,
aiding in enhanced convergence and large-scale ascent. And with this
track and a very favorable dynamic and kinematic environment,
traditional thermodynamic evolution, such as instby, tends to become
slightly less important as the mass transport/response can often be
sufficient to produce strongly-forced vertical ascent amidst an
increasingly-frontogenetic response.

Looking more closely at some of the ingredients... the deep-layer
bulk shear of 70+ kts will be /more/ than supportive of storm
organization, likely manifesting itself in a SSW-NNE linear
convective structure for the overnight period, especially
considering the /largely/ unidirectional profile with favorable
vertical speed shear in place. A /very/ robust H9 LLJ of 45-50kts
and H8 LLJ of 60-65+ kts will overspread the ILN FA toward midnight
and beyond, supporting tremendous LL mass response and ascent. It
does appear there will be at least /some/ cross component of the LL
bulk shear vector to the front itself, helping enhance LL shear and
SRH, supporting circulations within any QLCS structure that is able
to develop. Anticipate that the magnitude of the LL shear (45-50kts)
may be sufficient to overcome the less-than-ideal angle overlap with
the initiating boundary. As for the instby... this may be one of the
main limiting factors, despite the impressive theta-e advection/LL
moisture transport north into the area ahead of the front (with sfc
DPs in the upper 50s and lower 60s and PWATS approaching
250-300% of seasonal norms). It is likely that one or more
convective lines may develop along a pre-frontal trough
initiallyback to the west of the ILN FA, with the front itself
hanging back even further to the west across MO late Friday
evening. Synoptic-based deterministic and ensemble guidance
continues to depict a narrow ribbon of several hundred J/kg
SBCAPE nosing north into IN and parts of N KY and W OH around or
shortly after midnight. This narrow ribbon of slightly more
favorable thermodynamics will likely overlap, at least in a
small spatial and temporal capacity, with the strongly-forced
and /extremely/ favorable kinematic environment in place as the
core of the strongest H8/H9 LLJs translates NE through the
region between 06z-12z.

So taking this all in from strictly a setup and ingredients-based
fcst perspective, there is certainly some concern that the OH Vly
may be subjected to a nocturnal QLCS, which may impact at least
parts of the ILN FA, on Friday night. At this juncture, strong
straight-line winds will remain the primary concern, but any
convectively-driven sfc wave development could allow for some brief
backing of the sfc winds ahead of any broken line, lending itself to
a non-zero tornado threat as well. Will continue to highlight this
threat in the HWO, and could very well see upgrades/expansion of SPC
convective outlooks to encompass more of the ILN FA as we get closer
to Friday night and we have a better look at some of the CAM
guidance.

The other item, and it is not an insignificant one, will be the
robust synoptic-based winds Friday night and into the day on
Saturday. In the WAA advection Friday evening/night ahead of the
FROPA, could very well see sustained winds of 20-25kts, especially
near/N of I-70, which in-and-of itself would be close to advisory-
level criteria. Behind the front during the day on Saturday, within
the increasingly-well mixed BL environment, we could see gusts 30-
40kts at times, again favored for locations further north.
Additionally, with a very moist and strongly-forced environment, any
training convective activity may yield localized flooding, despite
the progressive nature of the system as a whole. With /some/ overlap
between the steering-layer flow and the initiating boundary, some
briefing training of activity will be possible, even with individual
elements moving quickly within the overall evolution.

[Bgoney]

Yea , I'd say the ILN boys are pumped they fi ally have something to analyze , niiiice!!

[cloudy72]

18z 3km NAM looks quite concerning for folks down in western Kentucky/Tennessee and northern Mississippi later Friday night into early Saturday...

nam-nest-ecentus-sig_tor-9198800.png

[tron777]

If the stronger Euro solution holds up, I would expect the SPC to expand the slight risk area to be a little further to the NE. We'll see as always. We have a couple of days to review the data. 18Z GFS took a step towards the Euro showing a stronger surface low vs the 12Z run. It's a little slower like the Euro as well.

[cloudy72]

If the stronger Euro solution holds up, I would expect the SPC to expand the slight risk area to be a little further to the NE. We'll see as always. We have a couple of days to review the data. 18Z GFS took a step towards the Euro showing a stronger surface low vs the 12Z run. It's a little slower like the Euro as well.

I agree Les, and also think areas to our SW like western KY/TN into MS will get upgraded to at least enhanced risk if the models continue to trend this way.

18z 3km NAM with a 992 mb low near Chicago around midnight Friday night.

[tron777]

If the stronger Euro solution holds up, I would expect the SPC to expand the slight risk area to be a little further to the NE. We'll see as always. We have a couple of days to review the data. 18Z GFS took a step towards the Euro showing a stronger surface low vs the 12Z run. It's a little slower like the Euro as well.

I agree Les, and also think areas to our SW like western KY/TN into MS will get upgraded to at least enhanced risk if the models continue to trend this way.

18z 3km NAM with a 992 mb low near Chicago around midnight Friday night.

I agree as well Mike. For us, I think it's more of a high wind risk with an isolated spin up possible. The better TOR risk should remain out of our local area, but not zero. If I recall, NWS Paducah had 4 tornadoes reported with the last system. If the trends continue this next system may do better then that down there.

[cloudy72]

Looks like the 18z GFS has trended towards the 12z Euro for Friday night early Saturday.