WhiteoutWX

I'm still not entirely sure how much weight to give the CFS dashboard...but I know last year we went the whole season without it looking anywhere close to as active as some of the recent runs have for later in the month, so I guess that's encouraging.

Yeah seems pretty clear the pattern will be unsupportive of much severe in the plains for at least the next 10 days. After that, like you said, models begin to diverge on whether we can get some western US troughing or continue with more of the same.

The bias with the new GFS (FV3) is actually to underdo precip on the backside of lows. Doesn’t mean it will always do that but something to keep in mind. Last three runs of GFS have been very consistent overall with the placement of the swath of snow from central OK on northeastward. It’s bounced around a bit with exact totals but that’s to be expected.

As long as the global models stay steady I wouldn’t worry about the NAM as much. It was the last to cave in the reverse situation from December of last winter where it was still showing major snows in OK when all the other models had started jumping ship. That said...this is definitely a low confidence forecast as the parameters that need to come together just perfectly here have a razor thin margin of error on either side. Too amped and it’s congrats Kansas. Not amped enough and you get the NAM solution or what the GFS had been showing a day ago.

GFS and ECM still have large differences regarding the trough amplitude in the Fri-Sun period. One (GFS) being much more low amplitude/zonal mid level flow while the other has much more meridonial flow over the plains as the trough ejects. I think for me the GFS would be preferred for more discrete activity and also would have a better shot at a multi-day threat. We know meridonial flow often gets messy. Either model would imply at least one good day during the period though. After that we may have a couple day break before trough reloads to the west. Also, GFS is showing the dryline getting pretty far east into Oklahoma and I would almost guarantee it verifies further to the west, which would bring it underneath more favorable wind fields than currently progged. Something to keep in mind.

I think the models have consistently shown an overall favorable pattern but have been jumping around regarding the ceiling of the period. Could be something great or could be something more along “average” climo for this time of year. Depends on how the trough orientation sets up and the individual waves eject out into the plains. Models have occasionally shown some blockiness over the eastern US as well which could complicate the setup some. Still far enough out that I’m just in a wait and see mode.

No one wants to jinx it given the past few years...

Pattern looks favorable for *some* type of winter system for the southern plains next weekend/early next week. That’s about all that can be said at this point. As everyone knows models have been abysmal this year in the day 5-7 range so expect tons of shifting around. Don’t hang your hopes on any one model run.

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.

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.

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.