GaWx

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.

I promise you that you'll survive. I've seen snow only once (for ~two hours) in over 7 years and was frankly lucky to see that. I'm alive and well! What doesn't kill you makes you stronger. I still enjoy winter a lot more than any other season because of the larger variability as well as higher % of lower dewpoint days making it more ideal for me for outdoors. And I can always dream of seeing another miracle snow whether it be this winter or some winter down the road. Meanwhile, I'm still hoping for another cold period later in Feb. As a matter of fact, La Niña/cold ENSO is (perhaps surprisingly) more conducive in Feb/March to an extreme cold shot into the SE than warm ENSO despite being warmer overall than El Nino per recent research I did going back to 1800s. I may share this later. A bit counterintuitive imo.

The 18Z GFS has almost pure snow for much of NC and has the heaviest snow there in many runs!

Absolutely, desperate times, indeed! But at least I'm not throwing the NAVGEM or CFS. And the big difference starts before day 7. At 168, the lowly regarded JMA has the 850 0C line 300-400 miles S of the others. Also, where the others have the 0C line then, the JMA has -10 to -15 C.

Starting at 144, one can see how different the 12Z JMA is vs all of the other 12Z runs with the southern lobe of the TPV further south resulting in colder air moving much further south into the S Plains. At 168 you can see how much colder it is in the SE with troughing to the Gulf coast along with an Arctic high bringing much colder air in vs the SE ridge hanging on all of the others. This is deep cold as opposed to shallow cold from CAD. I'm assuming the outlier JMA is going to end up wrong based on it largely being an inferior model, but thought it was worth documenting this in case it were to score an upset win.

The 0Z GFS/GEFS are mainly warmer in early Feb than prior runs as the SE ridge dominates.