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There is a lot of warm air advection at mid levels.  There's no closed 850 mb low to keep temperatures colder; the precipitation is basically one prolonged warm air advection event until Sunday afternoon when 850 mb winds turn northerly. This seems like a case where models would be more likely to under-do this warm air than over-do. I'd be hedging lower on the snow totals, higher on the ice/sleet. 

It’s another complicated setup. I fully expect it to evolve further, but I’d say anyone in northeast OK, southeast KS and eastward has a shot for this to trend favorably.

The showery and spotty nature to the precip with temps near freezing doesn’t have me enthused about accumulations for OKC area. Lull periods will allow for melting, if we can ever get the precip to flip to all snow in the first place. Back and forth precip types dependent on rates so far.

Well 00z Euro actually bumped north from its 12z run, dumping a lot of snow in central OK. 6z GFS is now slightly north of 0z. Has the south trend stopped? Hard to say but man it is going to be close for the OKC  metro. 

I'll believe the mesoscale models on things like temperatures and banding potential for winter storms. Believe the globals on things like synoptic details such as strength and track of the upper low, which is the key uncertainty here, not temperatures. 

People probably remember the NAM was the last model to jump ship with the December bust. GFS went first, then Euro, then the NAM. Right now GFS is doing a hard brake on this storm. Will see if other models also jump at 00z. My guess is NAM caves, but we'll see. As I said earlier, cutoff lows are infamous for surprises. What makes them so fun but also so frustrating to forecast!

Latest GFS/FV3-GFS both coming in weaker and further south again. Barely get significant precip into OK. If that ends up being reality that will be 2 scores for the GFS this winter, as it led the way with the December bust and has consistently been on the weaker side of the guidance envelope with this system as well. 

Caution on using those freezing rain maps. All that is is the amount of precip that falls as rain with surface temps below freezing. It doesn’t take into account accretion efficiency or anything like that. Can easily cut those totals in half or more for what would actually accrete on trees except in the most perfect accretion conditions, which this will not be.

Another important thing to watch will be freezing rain potential. Models were about 2-4 degrees too warm on highs today. That margin will be crucial heading into tomorrow and Thursday.

Cutoff lows are notoriously tricky to forecast. This one is no exception. I've seen some crazy last minute changes with these types of systems, even within 24 hours, so it's possible we see some favorable last minute shift...but I agree that the overall trend today has been slower, further south, and warmer. Again that favors SW OK and parts of western north Texas that will be closest to the center of the upper low as it ejects, and therefore will have the best overlap of colder temps and best dynamics. 

Models are in pretty good agreement of a pretty stubborn warm nose at 850mb for most people north of I-40 and east of I-35 in Oklahoma. This looks like a southwest OK special to me, with OKC metro still close enough for some favorable shifts. Tulsa and on NE I'm skeptical they see substantial accumulations as the surface temps are warmer and mid-levels just take too long to cool. 12Z NAM shows a narrow deform band for NE OK/SW MO but the location of that will continue to shift around.

IF that deform band can become a little better organized than shown then we could see more substantial accumulations along the I-44 corridor, but the temps are going to be razor thin and will require some heavy rates/dynamical cooling for this to happen. Definitely a low confidence forecast still.

Euro absolutely crushes OKC-TUL corridor with narrow but heavy deform band. 

1 hour ago, garfan said:

I like the image above, but there is no way that will happen. I do find it odd, but slightly humorous that the Oklahoma TV stations at least on social media (Facebook/Twitter) are pretty quiet about what might happen regarding this potential winter event.

Well after the major bust with the last winter storm in early December I think most mets are taking an understandably more cautious approach this time.

I think someone between Abilene and Ft. Worth has a decent shot of some accumulating, heavy wet snow Thursday late afternoon into Friday morning. Exactly where is highly uncertain and it’s likely to be a small area with the right overlap of heavy rates and cold mid and upper level temps on the west/northwest side of the upper low. I think most of Oklahoma will be too far north for this one (again!), but ULLs are notoriously tricky to forecast so don’t be surprised if there are some last minute adjustments. One thing that looks clear and will be widespread will be the WINDS on the backside of this thing. Widespread 50-60mph wind gusts look likely west of I35 in OK and Texas.

2nd highest single day December total on record for the airport.

Let’s be clear this wasn’t just the NAM busting. Up until 00z last night the Euro also had a significant winter storm. As much as everyone hypes up the Euro as being the best model it’s not invincible and is just as capable as he other models as flopping hard.

The key to this whole storm working out for OK and surrounding areas now lies with a little shortwave that is forecast to drop into the northern plains and interact with our system. The models have trended stronger overnight with this shortwave and it has the affect of interfering with our storm and prevents it from wrapping up quickly like the models were showing yesterday. The result is a weaker storm that is further south and warmer. With such marginal thermal profiles you NEED this storm to wrap up quickly for those heavy snows on the backside. Otherwise there will be a lot of disappointed folks with some light rain wondering “where’s the snow?”. Will be interesting to see what the 12z models have in store, but I’d say overall the trends are pretty discouraging.

4 minutes ago, Weatherdemon said:

GFS at 3.3 inches by 21z Sat in Tulsa. That's already 2 inches more than previous run.

GFS just playing catchup. Gets the overall look a little better this time but the QPF is too low on the backside of the low. 

This storm may have started out looking like an ice event days ago, but I think the true story will be heavy deformation snows on the backside of the system. NAM is painting quite the potent band, and while it's temperature are marginal verbatim, just looking at the synoptic features and applying conceptual models, it will be a heavy, wet pastejob of a snowstorm for someone over western OK, possibly extending into northern/central OK depending on the track. This would likely continue on east from there. I think the GFS is total trash at this point. NAM and Euro all the way. But JMHO...

53 minutes ago, rockchalk83 said:

With a more amped system as the NAM & Euro would depict, is there a chance the system moves back north? The 18z GEFS seemed to suggest some decent snow accumulations into southern Kansas and Missouri. 

Really would depend on the track of the upper low. But usually more amped equals further north. Until the other models start showing it though I'm not quite biting yet.

NAM hangs the energy back and is slower like the Euro. But it’s also more consolidated and amped with the upper energy. Closes off at 500mb and looks to have quite the backside snows. Really this is a much different storm depiction altogether than what was being shown yesterday and previously. Models were then showing mostly a warm air advection/overrunning scenario and open wave. This is a more consolidated storm. Long range NAM so beware but the Euro was also slower so this could be the start of a trend. 

GFS just seems unrealistic to me. However, the keys here are the surface wind direction, as well as keeping steady precipitation falling during the day. I think this may be what is contributing to the warmer solution on the Euro. It brings the precipitation in much later, starting Friday evening really. Without precipitation falling/wetbulbing processes...the marginally cold surface temps will be able to warm sufficiently during the day on Friday, regardless of wind direction. The NAM is really the perfect scenario if you want to lock in the surface cold layer.

The NAM just locks in that surface cold layer and never relents with a lot of freezing rain and sleet across central OK. Looks like it wants to drop some heavy snow on top of that just after the end of the run too. Seen many times where the global models scour out the cold air too quickly in these types of events. Even though it is long range NAM, meteorologically speaking, there's no reason for the temps to warm at the surface like the GFS is showing if we keep a continued northerly surface wind and attendant cooler/drier air feed. The NAM just seems more realistic to me.

Not really buying the GFS temps at the moment. But it comes down to how quickly the high to the north moves east. NAM keeps it more overhead and therefore keeps a more northerly component to the surface winds, and hence colder temps. GFS moves it out quicker and winds come around more easterly. 

Much warmer across Oklahoma too on the Euro. Went from being the coldest model to the warmest. 

3 hours ago, Doramo said:

Don't write much but am an avid follower and love to read y'alls take/ input.      I have a question  about the lack of snow for the past three winters and it is,  has this ever happened before in this area? We are talking about the overall area that is covered here. I have not seen any snow consistency records , don't know if there is such. Just curious .  I'm thinking surely that we could not go another year on the skimpy snow can we?

I can't speak for the whole area but I can tell you that for Oklahoma City the period from 2015-2018 had the lowest three winter snow total on record there. It's been rough out there for snow lovers.