Carvers Gap

Will be interesting to see how this plays out. Both the CMC and GFS have extreme AN high pressure just after d8 dropping into the Canadian prairie and Montana. That is syncs nicely with the MJO looks from the morning.

Just looking at NCEP MJO stuff this AM...definite trend to head towards phase 8. Many of the OLR maps also show this. I noted yesterday that I wasn't overly enthused with the MJO as most models had it stalled in phases 6-7 which are warm. Let's see if modeling doesn't react to that trend today. If anything modeling may have gotten ahead of itself yesterday. That said, if the trend to move towards 8 is legit, then I think we are in business. Right now phase 6/7 is going to fight everything. (NAO has saved us from the torch all winter and has been a key driver this winter). For several days it seemed the MJO plot and actual modeled OLR maps were out of sync - meaning OLR looked like phase 8 but the plot was not. And again, this really seems like the '89/90 analog merged with the '95/96 analog. I think we just need to be ready for some wild swings in modeling coming up.

It may have been. Have you seen where it was upgraded?

Just now digging through ensembles this morning, I don't see a ton of major changes to the pattern overall. If there is one trend it is to shave off the cold on the SE end of the are of BN heights which extend from the Mountain West deep into the SE. We will watch trends today. Again, the 6z GFS has the cold back on its run, though about 72 hours later. Dig through my comments yesterday, and I said rthat the MJO phase 6/7 was going to fight the cold. That is a very warm MJO signal. You can see the SER try to pop but get knocked down by the cold. Occurs at least a couple of times on the Euro run. What we do have in play now is very cold air at times making intrusions into the Lower 48. I still think the potential for severe cold into our area is very real. I just think modeling is trying to get the timing of each system down, and as Holston noted, modeling really struggles when cold air is on the playing field. As for storms, systems that run the gradient are tricky. But I will say if you want big snow, you really have to be willing to be right on the edge where the freezing line is. Again the 6z GFS is probably the coldest run that I have seen for my area in many years. Going to be plenty of fluctuations. if we get any snow on the ground before the cold moves in, that is going to be some seriously cold air sliding in along the snow pack.

Going to make a correction...the 6z GFS does indeed have record cold back on that model. It is in the d7-10 timeframe but looks remarkably like the Euro yesterday. Temps overnight in my area on d10 are -8F to -13F. There is very nearly some -20 stuff in SW VA.

Thing to remember about the UKMET, it has a tendency to oversimplify in the mid-range. Just have to take into account that bias.

I just use the UKMET on Pivotal.

Good point. Any time there is severe cold on modeling, things can go haywire in a NY minute. Will be interesting to see where this all goes during the next 72 hours.

The problem is that the Sunday system is just missing a phase...literally by hours. That could change. Interesting find on the UKMET. Did it have anything yesterday? Thought I remembered a whiff on Pivotal?

Thoughts on Sunday are still generally the same. If we assume the 6z GFS(not the para) is East of where it will verify AND the northern stream stays with the same speed, I think that will be a bigger storm. Should know by tomorrow morning what that trend is(meaning does it trend back towards a phase?). Seriously though, if that thing phases it could cut well west of current solutions. Again, pretty much out of runway by mid-day tomorrow on that system. I would think if it trends back towards a storm, that would begin to trend that way today.

Yep, it is a day old. Give me a sec to amend my comments above. Saw 6z and assumed it was legit.

Man, hope I am not looking at an old run...let me check.

May be running out of runway for the Sunday system. I think the trend is OTS with no phase, but going to watch modeling today to see what happens. Likely is nothing, but not sleeping on it either. The 6z GFS and 6z ICON are not completely benign. The cold is less severe (speaking in generalities) on modeling this AM, and that includes pretty much all of the Lower 48. As John notes, the trough amplification is massive and suppresses everything. We can get suppression without the vodka cold. However, I will note that has been an error all winter on modeling re: the SE. Generally, modeling has over-estimated the depth that cold penetrates into the SE at mid-range. Just take a look at d5-7 now. That front is not going as far south as was originally projected, and allows for rain for a system, which at one point, was snow without a doubt. One of the reasons I really like cold on modeling is that modeling has been modifying it of late. I still think we see cold. Would be somewhat surprised if someone in the subform doesn't see accumulating frozen precip during the two weeks which follow Feb 5th. A

Solar has been way, way off. That last cycle was weak(as predicted due to the sun going so quiet around 2010 I think). That definitely coincides with a lack of moderate/strong La Ninas. I always think moderate to strong La Ninas reset the temp gradient in the equatorial Pacific. For those of you who don't know what I am speaking of(I know Tellico does), we are used to weak El Ninos being great winter weather signals. However, for the El Nino to be a strong winter wx signal in the East, the Sea Surface Temps(SSTs) need to be colder in the places which are not part of the El Nino. The stronger that temp differential(the gradient) between the Nino and the rest of the Pacific, the more likely the El Nino behaves as normal. With SSTs above normal in much of the Pac for the past 4-5 years, the Nino climatology was been washed out. I am hoping that this La Nina will allow the next Nino to have a stronger gradient and behave more as a Nino would. As Tellico notes, all of this is likely tied together. And again, the AMO cycle is only about 2/3 of the way through - maybe it will end early? I do hold out hope that this year's unexpected -NAO cycle this winter might well be a harbinger of better winters to come.

Great question. Makes me wonder if the abnormally warm Pacific (due to a decadal trend which features a lack of moderate to strong Ninas balancing surface temps) has created a lack of gradient which is affecting global wind patterns. Just spitballing, but I know Typhoon Tip has talked about ENSO analogs being less effective due to the lack of gradient. Maybe this La Nina will add some balance to the force so to speak.

The 12z/18z GEFS and 12z GEPS look decent in the LR regarding the 500 pattern. Thinking back just a few days, that is a pretty big move in the LR.

Will give it a read! I know very little about weather events during that time. I have done a little bit of reading about the Great Blizzard of 1888 and some blizzards in the Plains during that time. MT and WY have some crazy cold winters. If the cold comes down the front range, there is nothing to stop it. It just banks up against the mountains. Really enjoy the climate in that part of the world. One of these days, I am spending a winter out there!

Thanks, Math/Met! Thankfully, the actual content(potential cold wx) is interesting right now. Honestly, just really thankful to see our board expand and still maintain such great content. We have so many great posters. I am always hugely appreciative of the contributions of the meteorologist on this forum. Just a small example, I had almost no idea that we had mountain wave events in this area until you started posting about them. Great team effort here by so many. Thank you again!

One quick correction. The most severe cold on the EPS does indeed bank briefly along the front range of MT before heading south and east. So, while we thought the Jan25-30 time frame might have some similarities to 95-96, we are now actually within 100 hours of a similar temp configuration (NW to SE band of cold temps across NA) coming to fruition. IF the EPS is correct, that temp configuration lasts from Feb 5 to Feb 18. We really can't ask for a better look on modeling and it is well within range now. We have noted often how this La Nina has elements of both '89 and '96. January at TRI finished 2.7 AN re: temps. What is being modeled is nearly opposite of that warm spell during January. Exciting times. This is why we do this. Might we strike out? Sure! That is just life in the Upper South. But history does show that sometimes we can do well with this type of pattern. Time will tell. Just enjoy the ride.

Here is the 12z EPS MSLP(mean sea level pressure for 240). So, just trying to see if the ensemble matches the operational. Looks pretty good, but more eastward with the core of the cold. The ensemble supports the UKMET operational actually. It does not bottle the cold up in MT. This is a great winter storm pattern IF it verifies, and IF we can get precip to time with the onset of the cold. Again, the slower this front moves...the better chance we get OR we get a higher frequency of systems from the southern stream. The ideal situation is that the front sages south of our area and stalls. If the SER fights(and it should), that would send multiple waves of precip along this cold air boundary - reference the blue arrow. My interest is in getting the pattern right - for now. I know we all love great snow maps, but that is a good look below. IF we can reel that in, that is the key... I think yesterday's snow map on the 12z Euro was just a warning shot by the model that things might get interesting. FTR, this might be 240 on the EPS, but the actual pattern(not to this extreme) begins about 132. We have seen this look past d10 multiple times this winter and it did not verify. I like right now that we are seeing this now in a 5-10 day depiction.

Pretty much a cage match between the MJO vs the NAO vs the SSW vs changing wavelengths of the season. MJO phase 7 centered on JFM is warmish over the East. Notice the severe cold over MT which fits the above maps. Thing is, the NAO is going to try to press that cold eastward with suppressed flow - will agitate that MT cold if you will. https://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/Composites/Temperature/

This is 144 on the 12z UKMET. That is -47F stuff in Iowa. Models "seem" to be signaling a major cold outbreak. Timing is EVERYTHING in regards to if/when the cold arrives and if it the southern stream will attack it(which I think it would). The Euro is pretty much the best solution as I look at the 12z suite. Yes, it is slower with the cold...but it holds the cold in the Plains. If that cold slides into the Midwest - it will be a major news story because of the cold and not snow. If it holds in the front range of MT and slowly heads SE(key being SLOW), that gives multiple piece of energy a chance to attack that incoming cold. Pretty much all modeling is showing severe cold...UKMET, Euro, GFS, and CMC. Duration, location of the worst of it, and extremes TBD. Sorry for the small thumbnail...had to resize it. Pivotal has the actual model run.

Really, after 100...The Euro is not too dissimilar to this 240 slide. Again, no reason to take a 240 slide verbatim. Simply showing the potential. The 12z UKMET was pretty much this cold at 144. I am just showing this so you all can see an expanded view of the MT cold with actual temps and not anomalies. That set-up is why we had such huge snow totals on yesterday's run at 12z on the Euro. The setup is still there, but the timing is different due to the range. D5-10 stuff is absolutely going to have lots of variability. However, when we look at modeling during winter, this is a great setup. Been a while since we have seen this on modeling inside of d10 .

Here are the anomalies in MT. I like front range cold in MT. That has a tendency to move SE. I am woefully low on my account memory, but here is the Euro at 240. It is simply slower with the cold - and way colder. Very difficult to find anomalies this cold. This is Siberia type stuff in February in NA. These are BN temp anomalies in MT during the middle of winter.....

Nah, it's just mid to LR forecasting - just all kinds of gremlins in play. I actually feel today's run was a big improvement to 0z. Yesterday's run was more for fun - no way we are seeing 36" in ten days. Honestly, since we still have cold in play and an active southern jet...I am encouraged. I doubt we have seen the last of the big snow runs though. I could be wrong, but with that much cold around and an active southern stream....like gasoline on a fire.