showmethesnow

I would be perfectly content rolling through the winter with this general look. Though this isn't quite the full month of November (through the 27th) it is close enough to give us a good idea of what heights we saw at 500's for the month. Very sweet look IMO. PAC looks great with a -EO/+PNA combo over cutting a weakness in the SW. Aleutian low with troughing extending towards Hawaii. EO/PNA delivers the cold, Aleutian low delivers the energy for an active PAC jet and NS. SW weakness provides a split flow and energy injected into the southern stream. The higher heights over Mexico/Gulf help bump up that southern stream into the southern US. Atlantic looks good as well. Central/eastern based -NAO to provide blocking. Higher heights in the central Atlantic to help offset the suppressive nature of a strong EO/PNA combo. If you also note the weakness extending between these two features (lower heights) this provides a slot for storms to travel through the 50/50 region potentially getting trapped by the -NAO. Between the PAC setup and the Atlantic we are see the troughing being forced into the eastern US. Also note the lack of lower pressures over the Arctic regions (-AO). I would take this look every winter and expect at worst an average winter with good odds of it being above to well above.

Besides the WAR looks fine to me without any major red flags. eta: guess I should have kept scrolling.

Yeah, I saw that as well. UL low captures the surface off the northern Jersey coast. One of the better scenarios. But as you said. Wheelhouse. Outside of.

Mesos are definitely icier then the globals. But we have been burned too many times outside of 48 hours, if not even 24 hours, on temps especially when the globals don't agree. The money runs will be tonights and especially tomorrows 12z where I am sort of expecting that they will fall more in line with the globals..

Not particularly concerned myself. Temps aren't exactly scorching in our source region (marginally above) and we are entering the time of year where we don't need Canada under deep blue and purples with neg anomalies. Also considering that the models have been erratic in the longer ranges when it does come to what we are seeing over the pole in regards to the pv I think it is anything but a slam dunk that the models have things nailed down.

No surprises on the overnight runs. Still looking rough on the front end with our best chances with the UL low rotating through. Couple of things may help our chances as far as the front end though. Timing, which occurs in the late night/early morning hours and the fact that quite often the precip will come in several hours earlier then forecasted potentially catching the cold before it escapes. At this point best case scenario in my mind is the possibility of a slushy coating around the PA line with others seeing some snowflakes/pingers in the air at the onset. Still looking at roughly 48 hours so let's see what the temp profile of the atmosphere looks like inside of 24 when we get inside the mesos' wheelhouse. As far as the UL low the pass it makes through the region is a good one. There are a couple of things in play here. We should have instability precip popping up within the core of the UL low which chances are good the models are under playing at this time. The UL pass argues that DC and south through northern and central VA are in the prime spot for this. Then we are also looking at the possibility of wrap around precip as we see interaction between the UL low and the departing surface low. This wrap around will favor the NW sector of the UL low as it moves through the region. Knowing this we are probably seeing most of MD in play with those north and east in a more favorable locale. Now the one big issue we are facing at this time is that the surface cold is lagging behind somewhat from the levels above it. So though we are seeing sufficient cold at 850 mbs and above what we are seeing at 900 mbs and below aren't with the surface quite toasty. With such a deep layer of warmth and the surface temps quite warm (seeing upper 30's-low 40's through DC/Balt corridor) seeing snow will be highly rate dependent. Now taking all of this in consideration best case scenario is probably spotty snow showers in the heavier convective cells within the UL low as well the potential for a band of snow within the wraparound where the heavier rates are occurring. A slushy coating or even an inch or two, though I may be stretching that, could occur within the wrap around band that potentially sets up (favoring those to the north and east of course).

No major changes on the overnight runs (GFS, Euro suites) just pretty much noise from the previous. Did note that we were generally seeing a little better heights to the NW of the closed low as it was moving into the Midwest and then dropping down. May have played a part in seeing a slightly quicker solution seen on the Euro. Then again it could be nothing more then noise. Except for the possibility of a couple flakes/pellets for some initially, the WAA looks to be pretty much on life support. Best shot at this point (given what is currently shown on the models) is the pass of the upper low through the region which is favorable particularly for the N MD/Pa line. Could see instability snow/showers with that feature as it passes through for the generally region and the northern/eastern sections could possibly get into a little wraparound/CCB action as the low departs. That will depend on the placement of the coastal low and the upper in relation to each other and whether a decent NE flow can set up in time. For those looking for a little more the best shot IMO is to see the Coastal low lag behind a little (farther south and west closer to our region) where we can see a little quicker/better interaction between it and the upper low. We did see some improvements in regards to the possible follow up 1 1/2 to 2 days later. Seeing the NS energy/SW dropping farther west and a little deeper out of Canada. This helps to set it up a little better as it crosses through our region. Below we have yesterdays 12Z. What we have is the trough that has reached a neutral state through W MD/Panhandle of WV. Take note of the minor height builds in front. The latest run is now showing the trough reaching a neutral state through eastern Ohio/Western W VA. Also note that we are seeing stronger height builds in front. This setup produces a trough turning neg tilt through the region opposed to the above which features a neutral. As depicted it could possibly produce a period of light snow through the region as it passes through but any impacts from coastal development would be slim to none. Now for those that may be looking for a little more from the above. We probably would want to see a farther west and deeper drop from this SW as it enters the central US. We also want to see greater separation between this SW and the current system we are tracking to allow better height builds in front of the trough. The objective with these two things is to see a sharper deeper trough that is going neg tilt a little quicker. This would allow for better snows as the system passes through. It could also possibly put the coastal into play for at least portions of our region. This is something to keep an eye on but it will be very dependent on what we see as far as the departing system (speed and placement).

I am guessing this is what you would call a -AO?

With that upper low passage it is hard to give up on this. But the last day and a half runs have been a death by a thousand cuts. 3+ days so there is still time but...

Looking at the greatest neg anom 850 temps they actually scoot to the south of our region with the 500 low passage. We are left on the northern fringe with very marginal temps. Would be hard to overcome the lower level warmth even with good rates.

WAA precip quite often comes in sooner then projected so there is always that.

Have to question whether the GFS bias for cold recently is also coming into play. So though we may get a better looking 500's we still lose the temps.

Just curious why you consider the current warming minor (which I consider pretty significant) let alone the projected one in early December that is showing a huge expanse of temps that are off the scale so we have no idea the true warmth. I am looking at the GEFS are you looking elsewhere? Or maybe you are going by the 10 mb winds?

I was looking at that this morning. Not familiar with it so I didn't want to comment. But you can see the temp spike of the AO as we have the pv crossing the pole. I am guessing the period afterwards may be reflective of warming considering winds slow during a warming phase?

So that's what a AO+++++++++++++++++ looks like? Would have never guessed. Was looking over the strat this morning and I have to wonder if we are on the doorstep of a SSW. The extreme warmth that we will see at 10 mbs which will be centered over the pole is now looking to propagate down to at least the 50 mb level. Have yet to find a site for the 100 mb or 200 mb level to get a read there.

Looks to be the same issue as the overnight Euro. NS is dropping farther south and to the west of previous runs so we are seeing the higher heights to the storms NE breaking down. Also doesn't help that the system is a little slower so that is giving even more time for those heights to drop. Doesn't help for our front end chances that we are seeing greater height anomalies within the ridge creeping southward as well. But we always knew that this one would be a tough one to bring home. Still 3 1/2 days to work with before the over running sets in so let's see where this goes.

Euro took a step backwards overnight. Very easily fixed problem though with a feature that the models mishandle all the time. Also shows the need for stronger ridging (greater height anomalies) located on the northern portion of the eastern ridge that I am sure some of you were shaking your head over when I mentioned it. ***Greater anomalies in the northern portion will not effect the flow through our region. But greater anomalies located in the southern portion will as they will push the boundary northward of us in advance of the system*** Below we have yesterday's 12z run. If you notice we have stronger height anomalies to the NE of the system running through the Midwest. These are important as they help to force the storm south as well as to help turn the trough axis the storm is embedded in. The stronger the better with this feature. These height anomalies are produced from the greater height anomalies we see earlier in the evolution in the norther portion of the ridge. As the ridge gets squeezed between the 50/50 and the incoming storm those higher heights get pushed northward.. Of note, also look at where the NS energy is located and pressing down (Black arrow). Now look what we have on the latest run. Notice that we are seeing weaker heights to the NE of the system. These heights were on par with the previous 12z run earlier in the process but now they are being beat down by the NS energy which is now dropping farther west. As a result we are nor seeing the system dropping as far south as on the previous run. Pretty much shows you how important that these heights are. But as I said it is a very easy problem to fix with a feature that the models mishandle all the time up to and even inside of 24 hours. ETA: Seeing the same issue with the NS on the EPS as well but not quite as extreme. Also seeing weaker heights in the northern portion of the ridge initially which is also translating to weaker heights to the NE of the storm later.

Models are trending favorably for the period shortly after the Dec 2nd event. Below we have the GEFS 500s from 2 days ago. Notice the deep push southward of the trough. Cold, dry suppressive look. Here is the surface. Pretty unimpressive for our chances. What sets this look up is that our Dec 2nd storm quickly ejects northward and reinforces the low in northern Canada. Now we have today's run at 500's. Suppression is gone. What we are now seeing is the Dec 2nd storm is taking it's time and rotating up through the 50/50 region. What this is creating is a small bump up of ridging in the east (red arrow) and in response we are seeing NS energy getting bumped southward (black arrow). And if you notice the surface we are now seeing low pressures dropping out of Canada and southward compared to 2 days ago which had high pressures. The GEFS isn't alone. The EPS has gone through same run to run changes these last couple days as well. Below is the current 500's Though not as pronounced you can still see the same features now showing up. Now I am not calling for a storm at this time. Just noting that the potential has ratcheted up a good bit from just the dry/cold and a possible clipper advertised a couple of days ago.

And did you hear the AO is going ++++++++++++++++++ as well? Fun times.

Seeing a pretty significant drop of the 500's compared to previous runs. I like.

GFS throws out the tease again for a couple days after the Dec 2'nd storm. Starting to get some somewhat promising looks on the models now for that period of time. Big player at that time is what we see the Dec 2nd storm do. If we can see a legit 50/50 from that system then it could possibly be game on.

The ridging (between the 50/50 and the incoming upper low) is a tricky deal. Might seem counter intuitive but we need that ridging initially to be strong in the upper portions of the ridge to help block the upper lows movement northeast. As long as the greater height builds are seen in the northern portion and the southern portion stays weak or even weakens we will be fine as currently depicted as it will not effect the flow through our region. Just follow the height lines from the Midwest into the east and you can get an idea what I am referring to. Now one other thing I haven't mentioned as of yet is that we are seeing the response that we see from the upper low (dropping southward through our region) because we are seeing this strong ridging. Take that out (weaken/squash/force south the ridge ) the incentive for the upper low to drop goes away. So the ridge is a necessary evil in this setup.

Whether some things or just noise or the real deal we are seeing improvements where we need to see them. We are seeing both the initial blocking over Canada a touch farther south and the ridging in front of the system is show better ridging in the upper portion where we need to see it. These are slight changes and could very well be noise but whatever they are they have slightly adjusted the upper low track when it gets handed off to the 50/50s influence. That is when we are seeing the biggest difference made. We are now seeing much more interaction between the NS energy (the energy that was screwing up the Canadian heights in prior runs) and the 50/50 (Saw this in yesterdays 12Z as well). If you compare this run to the previous you can see how this is impacting the flow in the N-Atlantic and it is a difference maker on the placement of the upper low off the coast.

Looking over things I thought the overnight models continued to show the possibilities for front end and/or back end snows for the Dec 3 system. There are a lot of things I could discuss on the setup but will try to make this brief and just focus on some things I think/would like to see in future runs. Really the key here is keeping that closed upper low in the west as far south as possible as it makes its trek across the country. So here are some things I will be looking for. Below we have the EPS at day 4. The Models have seemed to settle on the NS that is dropping down from the pole to play nice for the time being. Wouldn't be overly comfortable with that being the case as I have seen the models mishandle NS energy up to and inside of 24 hours. But for the time being let's assume that this will be the case otherwise nothing else that follows will mean anything. So notice without the NS breaking them down we are seeing height builds/blocking over top of our system which will counter the systems tendency to move northward through its initial eastward movement. Now what we would like to see on future runs is that feature come in stronger and/or further south. Now if you notice the ridging in front of the system that will play a key as the system enters the central US. There are several things I am looking for with this feature as the system begins to get handed off from the initial blocking over top. Notice that we are seeing the higher height anomalies in the upper portion of the ridging. This is important, see these greater anomalies in the lower portion or even spanning the whole ridge from North to south and it is probably game over. One other feature with this ridging is notice that is making an attempt to hook over the top of the approaching system. These two features of the ridge will fight against the system gaining latitude as it begins losing the initial blocking over top. So what I would like to see are stronger height anomalies in the northern portion as well as a sharper hooking over top the system (hopefully we see a distinct hooking of the greater anomalies as well). We also want to see this feature hold on longer, the longer the better. The final hand off with this system and probably the most crucial (if we haven't already lost the low because of too much latitude gain) is what we see when the ridging hands off to the 50/50 influence. We lose that ridging too quickly and/or it is weaker and we will see the storm gain too much latitude in a key area before the 50/50s can take over. There is one last thing I will be watching and that is the 50/50. Right now the models have been pretty steadfast on a strong system in the general area now shown. So let's assume that will be the case otherwise different placement/strength and it changes the equation. Now the one thing we are seeing with this low is it is departing NE as the system is approaching the Midwest. But have that depart 6-12 hours later (assuming we have a decently positioned upper low) and things become very interesting very quickly. ETA: Or the storm moves in quicker before the 50/50 can depart. Anything that closes the gap between those two is good. One last comment. The roughly day 8/9 period has had my interest for several days now despite the suppressive look we have been seeing quite often on the models. I will just say my interest jumped by a couple of magnitudes after seeing the overnight runs. But day 8/9, enough said.

If you look at the very end of the run you see the possibility of ridge bridging across the pole between the EPO/NAO, EPO/Central Russia, NAO/Russia or even possibly all three. Not a bad place to be for our winter chances. Of course this look will probably be gone the next run.