GaWx

The table (SSW plus MJO) per models is being set for this scenario though it could start during the last part of Feb. I just did a time lapse on Tropical Tidbits of 0Z GEFS runs at 10 mb for the forecast date of 2/15 starting with the 1/26 run and ending with the 2/1 run. It clearly shows a continuing trend of a further S SPV along with a further N high. The further S the SPV and the further N the high, the more the disruption/warming. The 2/1 run location of the SPV on 2/15 is ~700 miles S of the 1/26 run's position, which was near Svalbard (80N). Now it is over N Norway (70N). Also, the main high as of 2/15 has moved 700 miles N from S of Alaska (55N) on the 1/26 run to Alaska (65N) on the 2/1 run. Along with this, the N Pole at 10 mb has warmed as of 2/15 from -64 C on the 1/26 run to -42 C on today's run. So, it has warmed 22 C just within 6 days of runs for the same forecast point (2/15). So, the GEFS has gone from showing nothing interesting in the strat 6 days ago (cold SPV over the Arctic) to a significant disruption/warming today for 2/15. That's why I didn't start talking about this new warming til yesterday. And the trend toward more disruption/warming on future runs may not be over.

The main hope I have for a cold last week of Feb into early March largely hinges on the degree of strat Arctic warming and disruption of the SPV at midmonth. GEFS runs since 12Z yesterday have continued to show significant warming along with a southward displacement of the SPV to N Scandinavia at midmonth. This is the kind of strat chaos that can shake up the pattern enough based on past cases to lead to a couple of week+ colder pattern in the SE that would start within 10-14 days of the "onset" of a SSW. With that kind of timing, any SSW generated cold could make it to the SE as early as during the last week of Feb. The MJO would likely be in a more favorable position at late month into early March to help out. Meanwhile, model consensus is still suggesting a short moderate cold snap ~2/11. The 12Z Euro *fwiw* even gives parts of NC several inches of snow then.

I agree to some extent since any cooling effects from a possible major SSW in mid Feb could easily extend into mid to late March when normals are a good bit higher. However, there'd still be hopes for a colder late Feb into early March. First, looking at non-El Nino years with a SSW in mid-Feb: Consider the cold that followed the 2/17/2002 SSW, which was 2/22-3/6. Also, the 2/11/2001 and 2/12/2018 SSWs had cold follow 3/5-4/3 and 3/3-3/15, respectively. So, there's some early March cold included with those last two. Looking a bit away from mid Feb: Late Feb: 2/22/1979 and 2/22/2008, I couldn't find any cold dominated period of note. But 2/21/1989 had cold dominate 2/23-3/9. Early Feb: 2/6/1981 had cold dominate 3/6-25. So, in summary, this all tells me that if there's a major SSW, potential cold could come in as early as the last week of Feb. The last week of Feb and first few days of March are still pretty cold on average (within only 5-6 of the coldest week in January) and are also within the climo active period for SE wintry. By the way, the 0Z GFS is another run with an impressive displacement of the 10 mb SPV!

Fwiw, the 18Z GFS, like the 0Z, has what may be a real live major SSW on it late in the run fwiw. For those curious, check out the N Hemispheric maps at 10 mb late in the 18Z/0Z GFS runs to show what I'm seeing. They show a significantly displaced SPV along with massive Arctic strat warming. These are both bordering on a 60N wind direction reversal from W to E, especially the 18Z.

If RDU's total were to remain at a T, it would be the first time that low since 2005-6 for those who didn't know.

There's increasing model support for a transient cold shot into the SE ~2/11. Let's see how this evolves.

Recent GEFS/GEPS/GFS runs are suggesting the possibility of a rewarming Arctic strat. toward midmonth along with another drop in the 60N winds. Link to follow the Arctic strat temps/60N winds: https://stratobserve.com/ens_ts_diags This doesn't mean I'm forecasting another SSW. (The most recent SSW ended up being "minor".) This is just something I'm following. If a significant rewarming/drop in 60N winds actually looks like it is going to occur, I'd expect to be discussing this more and more down the road.

The UKMET, which had as much as 0.5" of ZR in parts of N GA/NW SC on Sunday on the 12Z run associated with a weak NE GOM surface low, has on the new (0Z) run no surface low due to a much weaker wave at H5. The result is much less qpf in GA/SC (under 0.1"), warmer temperatures, and no wintry precip.

The 12Z UKMET has a bigger deal than other models in parts of N GA and NW SC Sunday morning. At Athens, GA, qpf is ~1/2" and temps are near 32. Thus on the border of 1/2" of ZR, which would be close to a scattered power outage situation. Keep in mind that wedged cold air is often underdone and thus colder as well as a larger area of sub 32 wouldn't be a surprise. Clayton, GA is 31-32 and gets ~.15, which may be sleet based on 850's near +3 C:

To show how much the ICON has been trending colder into the SE resulting from the Arctic high bringing record breaking cold into the NE this weekend, here are the SLPs at Columbia over the runs of the last few days as of 10AM on Saturday 2/4: 1/28 12Z: 1019 mb 1/29 0Z: 1033 mb 1/29 12Z: 1033 mb 1/30 0Z: 1033 mb 1/30 12Z: 1037 mb 1/30 18Z: 1040 mb!! That's 30.71"! The 18Z ICON has a freeze all of the way down here that morning after being down only into the low 40s on the 0Z run.

I got ~2" since yesterday! Over the last 9 days, I've gotten ~4", which is about as much as I got from November through Jan 21st thanks to La Niña induced dryness! This is helping the drought conditions immensely. Kudos to the Euro and others for picking up on this El Niño-like wetness late this month.

Looking more closely at the ZR on the 12Z GFS for late Saturday night til ~noon on Sunday, it has mainly <0.25" from the NW half of SC to central NC. However, it does have a smaller area within this of 0.25-0.45" between Charlotte and the Triad. It gets as cold as upper 20s in Charlotte with the ZR. The GFS also has snow (850s below 0C) to the NW of this area.

The 12Z Euro has a high on Saturday (2/4) not getting above 32 in Raleigh. The coldest of the weekend is low 20s on it. This is looking to easily be the 2nd coldest airmass of the winter to date there and in much of NC. In addition for ice fans, there are hints on the models (as per the GFS post above) for some ZR in NC, northern SC, and NE GA (most likely not heavy enough for outages but more of a travel hazard if it occurs) on Sunday though I don't see any on the Euro. Regardless, this weekend is looking to be cold in the SE with record cold in the NE.

That's what the latest CFS thinks lol. After the extremely cold NE shot this weekend, it has a break for 12 days before 3 more extreme airmasses plunge down between 2/17 and 2/28 in various parts of the US. We know any cold extended portion of a CFS run is pretty much pure entertainment. But this does remind me that we have very little idea about how the last half of Feb will be. After all, Feb 15th is still 2 days beyond the end of the EPS, which itself is very unreliable. And keep in mind what I said about knuckleballs. As we get into mid Feb, that's when we may have an MJO move back to inside the COD and away from the MC. Also, if we are to get a SSW induced -AO/SE cooling, it could easily start then based on analogs. Regarding the very strongest Arctic plunges deep into the SE in Feb, most have actually occurred during either La Niña or cold neutral despite the relative rarity of cold Niña Febs. A good number of these were during 2/8-2/17 although they have occurred as late as 3/7! A good portion of these followed a mild period. The Arctic's coldest normal is not til 2/25! Regarding major snow/sleet in the SE, climo is still relatively favorable through the first few days of March. In RDU, the peak day is actually March 2nd! ATL has had several major winter storms in the first few days of March. Even way down here where big winter storms are very rare, two were between 2/25 and 3/4 and there have also been several non-major wintry events within that period! Just some food for thought.

Followed by a late winter?? Anyway, nothing is certain in the wild and whacky world of wx! Just when you think you've got it figured out, in comes a knuckleball.

I had been hoping that the Euro idea of the MJO going into the circle (which typically wouldn't be a warm signal) before reaching phases 4/5 (which is what GEFS had) would occur in Feb. But it looks like GEFS idea, which favors warmth at midmonth, will win out as the Euro has been inching to the GEFS. Also, the progged +NAO/AO aren't favorable for cold.

Below is a graph showing that the 10 mb winds at 60N dropped sharply from 50 m/s on 1/23 to 12 m/s on 1/28. It needed to drop to <0 to be counted as a "major" SSW. Instead, I expect it to called a "minor" SSW. The models did a good job as they had it drop to this vicinity for a good number of days prior to 1/23. Does it going 75% of the way mean it will still likely have significant cooling effects on the SE starting mid to late Feb and lasting at least a couple of weeks thanks largely to a new long period of -AO? I don't have a good feel for it as the analyses were based on major SSWs. And the model consensus is forecasting some restrengthening of the SPV along with cooling back a good bit in early Feb.

Followup: The 12Z GFS is the coldest yet for NYC and vicinity. However, most of the rest of the models weren't as cold as at the 0Z runs.

Per Tarboro records, there was only a trace of snowfall in Jan of 2001 and that fell on the 9th. After that, the rest of the month was very dry and averaged slightly AN with temperatures. So, with Tarboro being only 10 miles away, I see no way that Conetoe got anywhere near 16" of snow in mid to late Jan of 2001.

The 0Z Euro/UK didn't back off at all in regard to the progged extremely cold airmass for next weekend in the NE. 850s once again get down to near record territory for the lower 48, close to -40C! NYC once again gets down to below 0 on 2/4! We'll see if this holds up in future runs. Also, this Euro was significantly colder in the SE vs the prior run. Edit: This as modeled is a historic cold airmass in the NE and it has been trending colder and colder even down into the SE at the bottom of it. Example: dewpoints over the last 5 Euro runs have dropped 30-50 F for 2/4 at 12Z! There's no telling whether or not this colder trend for next weekend will continue. But if the trajectory of this airmass were to shift more in our direction, it could trend a lot colder. Something to watch!

Followup: 1) The 18Z ICON at 120 suggests that the maps for late week would likely have been colder than the 12Z in the NE. 2) The main reason for this post is the 18Z EPS 144 (end of run), which is significantly colder than the 12Z EPS 150 in the Midwest/NE and is absolutely frigid in SE Canada. Will 0Z runs back away, maintain, or be colder than earlier runs? We'll know soon. Edit: 0Z ICON is much colder than the 12Z in the NE US next Saturday with a deeper plunge of the extremely cold SE Canada high! Also, that leads to a colder SE vs the 12Z due to much stronger wedging.

More on how cold next weekend's airmass might be in the NE, which would be relevant to how cold the SE may get via wedging: For the record (not because I believe it though it will be interesting to follow), the 12Z Euro has -2 at LaGuardia at 168! That would be the coldest there since the -3 of 1/19/1994. But that's very likely going to verify too cold being that it is an extreme operational run at day 7 and there has been a cold bias with models overall. To show how extreme this run was, it had +10 there on the 0Z and low 20s on yesterday's 12Z. To compare for the 12Z runs, the UKMET has +6, GFS +18, CMC +19, and ICON +23. The 18Z GFS is much colder than its prior run and has +6. This extreme Euro run has -40C at 850 mb then in N ME, which would not be far from the coldest on record in the lower 48/just above the coldest in the Midwest for the 1/1985 extreme outbreak. The CMC also has -40C while the UKMET has -39C and the JMA has -37C. The 12Z GFS has it down "only" to ~-31C. Regardless of the likelihood that the 12Z Euro is overplaying the degree of cold at the surface, there may very well end up being the coldest air in a good number of years in the NE a week from now.

For the record (not because I believe it though it will be interesting to follow), the 12Z Euro has -2 at LaGuardia at 168! That would be the coldest there since the -3 of 1/19/1994. But that's very likely going to verify too cold being that it is an extreme operational run at day 7 and there has been a cold bias with models overall. To show how extreme this run was, it had +10 there on the 0Z and low 20s on yesterday's 12Z. To compare for the 12Z runs, the UKMET has +6, GFS +18, CMC +19, and ICON +23. The 18Z GFS is much colder than its prior run and has +6. This extreme Euro run has -40C at 850 mb then in N ME, which would not be far from the coldest on record in the lower 48/just above the coldest in the Midwest for the 1/1985 extreme outbreak. The CMC also has -40C while the UKMET has -39C and the JMA has -37C. The 12Z GFS has it down "only" to ~-31C. Regardless of the likelihood that the 12Z Euro is overplaying the degree of cold at the surface, there may very well end up being the coldest air in a good number of years in the NE a week from now.

The coldest of the winter to date by a good margin is going to be close to, if not in, the NE possibly down to NYC a week from now (2/4) per the 12Z consensus. Something to watch to see how strong of a wedge, if any, would then get the low level cold into the SE. The 12Z Euro is the coldest run yet next weekend in much of the SE with hard freezes at least down into NC. The GFS combines this strong NE cold with moisture to yield wintry precip in the main Carolina CAD region. The PNA has trended toward a decent + for next weekend. Edit: the 12Z Euro has the coldest in Boston and Hartford since at least 2016!

The 12Z Euro's H5 SE ridge, when centered over the FL Strts late Wednesday morning is up at a whopping ~593 dm, the strongest yet for it on any of its runs.