Carvers Gap

I "think" we are looking at potentially very cold temps during the second week of Feb. The AIFS at 12z hinted at this. It is there about 2/3 of the time. @Daniel Boone, I suggested(then deleted quickly!) that we start a February thread. I thought I was in the January thread. No, I was actually IN the new February thread asking for the February thread to be created!!!! LOL!!!!

I like that meme, man. I am gonna use that for personal use.

Speaking of the "fun begins at 50," do I dare admit that I thought I was in the January thread when I recommended a February thread get started? ...and I was actually posting in the new February thread.

I think the warmth we are seeing (to end the month and begin Feb) is the model reaction to the MJO passing through phases 4-6. So far(famous last words), that looks like a pretty fast pass. I was a bit perplexed that it hadn't shown up. At one point there were below zero temps in the middle of my warm-up! It is always possible that winter doesn't return, but I am rolling with '96 which had a warm-up in between cold shots. Right now is halftime - I think. A January thaw is almost always a staple of winter, and quite honestly, I could use one. The treadmill sucks for running! I don't do single digit wind chills. I am older and smarter... As one in my family likes to state, "The fun begins at fifty." Somehow, I don't think that is a compliment!!!

Here is the time frame that I continue to watch along with the timeframe around roughly 1/30(give or take a few days). The real question in my mind is where does the stationary front set up shop? Is it the Cumberland Plateau or the Apps? I have asked that question already once this winter. Turns out, it was Pensacola! This time frame sits just beyond deterministic and global ensemble range. Gonna have to slog through a ridge or two to get to potentially this - beware!

The 18z GFS just hammered the Southeast(portions of TN included).

The 18z GFS is interesting at d10.

Mississippi is always a tough sell for snow, but I admittedly don't watch MS much during winter. If the cold is deep enough though, it could. Northern MS is in the game in my book if overrunning persists on modeling.

Just looking across deterministic runs d10-15, there is decent agreement of very cold air invading the Lower 48 again. To me this looks like a front range(of the Rockies) or Plains initial shot. Then the real question that arises is how far to the east does it spread. All three globals have cold racing down the Canadian Prairies at the end of their runs. The Euro manages to get the cold all the way to the Gulf Coast yet again. The Euro has a fairly extreme blocking scheme over Alaska. That is the mechanism that was missing yesterday. I still think the cold (potential)shot is just at the fingertips of deterministic runs and we will see variation for sure. I get pretty excited about cold during February. We haven't had a lot of that recently. Cold February storms will often over perform which is why they are fun.

The biggest thing I have to change(in my thinking) is now climatology supports heavy snow in the Florida Panhandle. LOL.

On the 12z Euro, it looks like a dam break(d12-16)....the entirety of the cold airmass in Canada heads south. BIG differences in the MJO. American modeling seems to have moved markedly to the Euro camp overnight.

12z Euro is crazy cold late in the run....might be the coldest air mass of the season if it verifies.

The SER is also showing up in d10-15 as well. That probably teleconnects well to the MJO phase. Looks a lot like phase 7. Now, we just need to get it around into 8-1-2 without a stall(probable).

Areas which have under performed would be the Plains(that might get fixed during Feb) and the NE Coast. W VA is just racking up snow. The southern reaches of the Sierras (just eyeballing) could use some more snow. The Gulf Coast is set for the next 50 years.

Intense cold in January can result in cold/dry. Intense cold during February can yield big winter storms in the Lower 48. Models will often underestimate the strength of storms(northwest jog) and underestimate precipitation amounts.

Yeah, sorry. You can see modeling adjusting today towards that faster MJO rotation. The 12z GFS has it.

Just looking at the morning MJO plots, the GMON(GEFS ext weeklies) finally broke towards the faster Euro solution which races through warm phases. That sets up the second week of February(edit) for maybe a return to cold temps. You can see the cold rotating down the Rockies and spreading immediately eastward at the end of the 0z Euro. The AIFS has it going down the front range - MAJOR overrunning signal for west Tenn if the AIFS is anywhere close to being correct. For now, I cautiously give the Euro a nod of a quicker return to cold. If true, that is eerily similar to 95-96 in terms of progression. LOTS of warm in between cold shots.

Ha! Yeah, man, I drove through that exact TRI area yesterday. It was how I would imagine a lake effect band (only much less!). There was a dusting and then 1-2" of snow all at once. It was probably 2-3 miles west of I-26. Definitely was related to some type of Bays Convergence.

Euro Weeklies Control is picking up another sharp cold shot during week 3. That is just beyond the reach of deterministic modeling right now. But you can kind of see it on most 12z modeling...push south of cold air.

This kind of puts in perspective the month so far. And honestly, I might not mind a 7-10 day warmup. Right now as I type the wind chill is 10F. TRI has recorded a trace or more of snow at the airport 10 out 20 days this month so far. Yesterday was 19 degrees below normal. During December, all of those LR ext models which called for January cold weren't too far off the mark. When it snows all the way to the Gulf Coast, that is a pretty amazing cold snap and one which leaves me a bit in awe. Look at those departures from normal. Only three days AN so far for the month.

Lastly, the 6z EURO AIFS really wants to leave the EPO in place but squashed. That would allow for periodic cold shots into the east. That might well be a direct result of the PDO being less hostile. The AIFS has been uncanny and rightfully stubborn in the long range. The AIFS is probably our best chance going forward. I give it a lot of weight. It is basically the zonal/chinook outcome that mention in the first of these four posts(this being the fourth). If the cold air supply is strong enough over NA, the MJO can do weird stuff(like the complete opposite of what the temp phase should be). That said, we are due for a pattern change if you go by the 4-6 week rule for patterns. So, I lean warm for the new pattern...but with great caution for Feb. This is one where I look over my shoulder on every run for modeling to flip cold in the East.

I do think a western Atlantic ridge (WAR) could fire later in the d10-15. That brings very warm temps to the area. But what do we remember about that feature during winter? It often shreads the TPV. If the TPV splits, we might not have to worry about the cold going to Asia. Why? It is already here. Wouldn't surprise me to see a legit strat split during early Feb which sends us into the icebox later in Feb. That is probably part of the reason why so many analogs are cold for March.

Below is why we have to tread carefully. The first slide is basically right now. The second slide is 384(looks quite similar to the ensemble BTW). See how much cold is in Canada. That is coming south at some point. My guess is the West will benefit, but any cutter through the Plains could bring part or all of that air mass southward. The 12z Euro has a strong SER, but that might be a buckle before the next air mass. IF....IF the Euro MJO is correct, that air mass is heading SE. If the American MJO plot is correct....that air mass goes west, and we have the SER. But that is a crap ton of cold in Canada to start February. Right now the cold is just rotating west to east along the Canadian/US border with zonal under it. It is rare to be dealing with so much cold in NA late in that run(common theme and likely correct even at that range). I am having to adjust a bit to having that much cold which could drop into the pattern very quickly. Normally, I would just go torch for Feb....but that air mass is going to have to reckoned with I think....guessing it will modify and the last 10 days of Feb is when we see it move east. But that is a guess only.

Looks like we are about to enter a time frame around Jan 30th when cold air delivery mechanisms will be largely absent, and zonal flow over most of NA will be present. There are still very divergent outcomes when we look at the MJO progression(both amplitude and speed) on several models. The Euro gets it rapidly through the warm phases. American modeling take it to 6 and leaves it there the rest of winter. During Feb, I suspect we see very small windows where it can snow. The cold air supply to our north is substantial, but with zonal...it is stuck there. I think we will still see strong cold fronts, but they will likely lack staying power. So, an precip(if we want snow) is going to have to be timed nearly perfectly. I continue to think March(and the latter half of Feb if we are lucky) will feature a final return to cold. We have seen two bouts(early-mid Dec and almost all of Jan) of cold already. One more appears likely. It wouldn't surprise me if it is the coldest against the norms. A word of caution...as long as that substantial pool of cold air lurks in Canada, any warm forecast is in substantial danger. Warmth could/should rule the day for February, but cold lurks behind any cutter which could flip the pattern on a dime. One thing we have seen with cold this winter, when we get it...it isn't halfway. For now, February looks base warm with some cold intrusions which could provide wintry weather if timing is precise. Otherwise, we wait until late Feb and early March. I suspect the modeled zonal pattern (beginning late next week) is likely the "new" pattern. However, zonal can be tough to maintain during February as wavelengths shorten up. I would suspect some of the Feb cold shots will not be seen until the last minute on modeling. That's about it. Pretty boring pattern on tap for a few days, but the pattern is capable of snow...so it is worth keeping an eye on. There are a few chances on either side of Jan 30th. Again, it would not surprise me to see a mix of severe and winter weather tracking for the next couple of months. Sidenote: Analog packages have been pretty stellar so far this winter. They picked up the conflicting signal for January. They had the cold end to November and cold start to Dec. Most are very warm for February. Many are very cold for March. 2017-2018 has been a great analog this winter.

it used to be that spring snow IMBY was not uncommon, and that snow during late November and early December was very unusual. That has flipped since about December 2009. Winter finds a way to get going early in NE TN more times than not lately. We can have cold/rainy springs..... Also, I am thinking what I looked at was snow and not temps now that I think about it. Though, there is prob some correlation there. Snowier falls and early winters. Less snow springs.