burrel2

Nah this is the Rgem. It's just a webpage where you can get the output a little faster than other sites. I've used it for years. https://collaboration.cmc.ec.gc.ca/cmc/cmdn/pcpn_type/pcpn_type_gem_reg.html If you go past 48hrs it reverts to the CMC map.

Rgem is well south. This storm's outcome is still TBD. Here's 1pm Thursday. NAM has snow ripping across the entire state of NC and most of TN at this point.

ARW2 is also not as amped up as the 12k/3k NAM, but it's close. It doesn't seem to have the warm nose though. NE-GA and the Upstate look like they're about to cash in big time on the ARW2. here's a comparison showing the ARW2 vs the 3k NAM thermal profiles.

ARW is way less amped compared to the 3k nam at 48hrs. As a result, it doesn't have the warm nose for the upstate and has some light snow breaking out around Anderson, SC with a sounding that's -1c or colder throughout the column and a wetbulb surface temp of 32 degrees. I hope it's right... Edit to add that the NMM variant is also way less amped.

Anybody know where to get an 800mb temp map from the nam? That would show the warm nose much better.

The 12z Ukmet sure does seem suspect now. Amazing how far apart it is with other modeling.

18z GFS ensembles... wow. Mean snowfall has went way up for everyone it looks like. I am way more worried about this trending too far north than too dry at this point. Even for places like spartanburg,charlotte, fayetteville. Greensboro to Raleigh has to be feeling good right now. Odds of them getting a major winter storm are well above 50%, imo.

Some positives for the upstate with this system: 1. We aren't relying on a wedge front to arrive for low level temps. Typically when we're waiting for a wedge front it's delayed. All the models have a brisk wedge front blowing through during the day on Wednesday. As such, the low level cold air feed is established well out ahead of this storm. Another positive, models often miss dew point depressions/dry air when the wedge is in place, as it will be on Thursday for the upstate. 2. We aren't relying on rapidly crashing 850mb-900mb temperatures from northwest flow as the storm arrives. The models have this air entrenched in our area and after wetbulbing gets most of the upstate to freezing or below on Thursday at these levels. Might this level be too warm for snow anyways? YES! But it won't be because the mountains have blocked it's advancement. Which is a battle we always lose. Some negatives: 1. Several models show a lee-side minima for precipitation. I think this is b/c they have northerly low-level flow on the west side of the mountains, causing some subsidence at that surface as air drops over the peaks. (Even though we have Northeasterly low level winds in the upstate, it appears there's a zone near the mountains that may be affected by downsloping. Especially in the NC foothills. 2. It appears the southerly push from waa around 750mb is so robust on the NAM that it sends a warm nose over the upstate flipping us over to sleet/rain. The upstate needs to hope the NAM is a little too aggressive in this regard,(which it probably is since it's on the extreme end of guidance, but you never know how hard that North trend is gonna hit!) 3. Some models are developing quite a coastal storm Thursday afternoon, if this consolidates quickly we could find ourselves in a precip minima between the initial frontogenesis forcing and the coastal low, (we've seen it happen before). Conversely, the icon swings a nice backside band from the coastal low through the upstate Thursday night, if that's true the coastal will have helped us. (very skeptical on our chances of this happening) Final Thoughts: I have little concern on whether the upstate gets appreciable precip. I am also not concerned about boundary layer issues given the Northeasterly low level winds forecasted well in advance of our storm. My biggest concern at this moment is mid-level temps if this thing really gets cranking like the 18z NAM showed. (I know it's early so don't take this as a prediction, these are just my gut feelings today).

NAM says there is some sleet with this system in my backyard. Where is this 800mb warmnose coming from? Valid 1pm Thursday.

FWIW, probably not much. But the 15z SREF mean trended a good bit further north and west with the higher qpf totals, comparing to 9z.

I know it's the 84hr NAM, but it looks like great for Upstate SC. 850's around -5c with surface dew points in the low 20's and heavy precip crossing the state line from Georgia.

Don’t think I buy that. Looks like it’s going to be slower to arrive on the nam which should help letting the cold air filter in. Hard to say for sure though. icon is in.... made a massive shift north with precipitation.

Well the nam looks interesting to say the least. Trough dropping through the west looks beautiful

It's early but the 00z icon is dropping our energy way farther west than it's previous run. Probably a good sign for tonight's 00z suite.

A decent tick north on the 18z GFS. Another shift or two like that and we're in business.

This is all a huge stretch. We're 120hrs out from the event starting. A small adjustment in modeling would lead to a widespread snow for lots of people on this board. Take a look at the snow from last week, when no global models were showing any snowfall just 72hrs out. I think that qualifies as a "comeback in the game" if you will. This storm has much better odds of turning out in our favor than that one did, 120 hrs out. It may not work out, but it's far from a "down 30 points at halftime" game.

Yea, the sad thing is we are still so far out. This thing could trend in to nothing on all the models, only to show back up 3 days from now! It is nice having something substantial to track though.

Depends on where your surface temp winds up. If it's below 32 then you'd be at 10:1 or better. Of course if it's 33 in the afternoon with a 2pm sun angle you will be lucky to get 8:1

As wet and over performing as all our rain events have been I highly doubt this system stays suppressed. As cold as the profile looks, if this thing can amp up a little more we could be looking at a foot plus type storm. Wouldn't take much adjustments to get inch+ liquid totals in to -5 850 air that's only getting colder as the system moves in.

Just for reference. The snow storm from last week was modeled to be 36-40 degrees by all the global models the night before the event for my backyard. That storm had a similar thermal profile to the one being shown. As it turns out I got down to 31.5 degrees and got over 3.25 inches of snow from just .35 inches of liquid. And the snow started sticking within a few minutes of falling. Now, if we only manage 1/10th of liquid with this storm then that might be problematic for accumulation(due to the boundary layer/mixing). But i mean you're only getting 1 inch even if every flake sticks anyways in that scenario. I guess my point is you don't need inch+ precip totals to overcome a very a shallow boundary layer. As long as we get 1/4 to 1/2 inch of liquid we should get a nice accumulating snow from this system,(if the thermal profiles are modeled correctly). If you're below .25 liquid totals for this storm, then yes, you probably won't get much accumulation outside the mountains.

Here is the 7am Thursday sounding for mby off the 12z GFS. That sounding has the freezing layer just 600 feet off the ground. If that sounding is correct, I have no doubt that I would be seeing accumulating snow with surface temps around freezing.

Surface temps are a non-issue with this storm for most folks, as modeled. Let me explain: If per say, the models were showing a profile with -4c 850mb temps, 0c 925mb temps, 1c 950mb temps and 3c surface temps. We would be in trouble in that scenario as we would be dealing with lots of white rain and a thick boundary layer that wouldn't want to give up the fight. That is not what any of the models are showing for this storm. There are (on average for mby) showing -4c 850mb temps, -2c 925mb temps, -.5c 950mb temps, and 3c surface temps. As a result, the above freezing layer is only a few hundred feet deep at most on the globals, and any decent precip rates in that profile will quickly get the surface to 32/33. The globals never pick up on this, especially at this range. So it's no surprise they are showing 6 straight hours of 37 degree rain/snow. In reality,(if their thermal profiles are right). that would mostly be 32/33 snow for everyone fortunate enough to get good rates, assuming your location has the good thermal profile I described above.

Yep, EURO is a swing and a miss. Luckily it's on an island with that scenario. CMC/ukmet/GFS/JMA are in agreement against what the Euro is showing for now.

Yes, in fact, ratio's could be >10:1. Here's the 850mb temps at 7am Thursday. -7C over Charlotte.

Here's the last panel of the ukmet. Vaild 7am Thursday morning.