February Pattern Disco

[40/70 Benchmark]

Warm start not withstanding, I'll be stunned if we are not much closer to normal snowfall headed into March.

[MJO812]

Gfs says what warmup

[Damage In Tolland]

Gfs says what warmup

[40/70 Benchmark]

Going forward, I think the pattern evolution is generally in alignment with prior posts, though, time will tell regarding the extent to which the reversal amplifies.

 

[1] The NAM transition into a predominately negative state has occurred over the past couple weeks, via tropospheric forcing mechanisms [i.e., Kara Sea ridge development, potentially instigated by a couple of background factors], stratospheric polar vortex elongation in response to initial strong wave-1 attack which has warmed the lower/mid stratosphere over the Pacific side of the Pole.

 

[2] Thus far, the severe -AO has not yielded any snowfall or extreme cold. The upcoming week will feature colder than normal temperatures. The rapid upward trend in both the AO and NAO modalities for the 18th-22nd period is a noted Archambault indicator for enhanced storminess / cyclogenesis along the East Coast. So the detection of a possible storm later in the week would coincide with statistics on prior sharp AO/NAO rises, and severe -AO dailies. However, if the western ridge amplitude is not sufficiently meridional and/or oriented more NE-SW rather than N-S, it will tend to force cyclogenesis too far S/E and push the storm offshore. This remains a possibility due to the off the charts +AAM state which has infused the Pacific Jet with incredible westerly momentum. The AAM tendency has been negative recently, but it is still very high. If the ridge remains amplified, there is enough downstream Atlantic residual blocking to prevent a warm/rainy scenario. Confluence appears strong. Largest risk is a S/E miss, in my view.

 

[3] The targeted period for robust wave activity [Jan 20-30] will be occurring with the strongest wave-1 pulse to date, in accordance with the discussed precursors. Forecasted wave-1 heights, historically speaking, would be sufficient to induce a vortex displacement. Typically, the initial wave-1 hit is separated by a couple weeks of depressed flux prior to the second, stronger pulse. A potent +MT event in East Asia could develop as wave-1 increases concurrently, and this would enhance pressure on the vortex. The one wildcard remains the anomalously strong condition of the vortex this winter, which may require stronger wave activity than is typically needed to force SSWs. With that being said, I think the probability is mod-high for at least a minor SSW, whereby zonal winds slow significantly and 10hpa temperatures rise sharply. I am not certain that we will achieve a major SSW displacement, but the time frame continues to be near the end of January for that potential.

 

[4] Regardless of stratospheric progression, other tropospheric indicators are suggestive of the overall maintenance of high latitude blocking in February. I expect that the Western ridge reload will be extremely transient. A classic Nino NPAC looks probable for the end of the month with the Aleutian low and +PNA. GWO orbit and heightened AAM state support the aforementioned regime of S/E US troughiness and Rockies ridging as the month closes. The expectation for February continues to be the gradual retrogression of the GOA with a -AO and -NAO in the means. Depending upon the evolution of the stratosphere, this AO/NAO blocking could be either moderately robust or severe / similar in magnitude to the January episode. An official displacement would heighten the probability of protracted blocking.

 

Overall, it does not appear to me that we are paralleling the Nino winters which were torchy / snowless from front to back. The second half transition still looks on track. January is falling in accordance with the analogs; generally a near normal temperature departures with improved high latitude indicators.

[NorEastermass128]

Looks like you and isotherm are on the same page, Ray.

GL!

[BostonWX]

Very very impressive winter outlook if this works out in february. Looks like a decent month.

[googmoog]

Thoughts on Feb?

[40/70 Benchmark]

Time to fire this back up seeing how ugly next weekend looks at present. 

[eyewall]

Time to fire this back up seeing how ugly next weekend looks at present. 

 

There is no getting around it the start of Feb is looking like crap right now. In fact I wouldn't entirely rule out a cutter within the first few days.

[CoastalWx]

I kind of like it. Big +PNA setting up after a mild start to Feb.

[Damage In Tolland]

I kind of like it. Big +PNA setting up after a mild start to Feb.

How torched will early Feb be? We talking 50's or just 40's?

[CoastalWx]

How torched will early Feb be? We talking 50's or just 40's?

Tough to say. The boundary is nearby and you know how that goes. Could be 50s or 20s at the surface. The overall "regime" is mild, but I couldn't say where we'll end up. I do lean mild though, but hopefully not too warm.

[Randy4Confluence]

A few mild days won't kill us...looks like a reload end of GFS op run with the -EPO and cross polar flow.

[ORH_wxman]

That early Feb setup is looking really overrunnish....it's possible we torch, but I also won't be shocked if we end up with a cold overrunning event. Euro ensembles actually have trended this direction the past couple runs....granted, it is 10 days out, so take it FWIW.

[dan123]

Does the pattern look stormy on the ensembles?

[40/70 Benchmark]

Tough to say. The boundary is nearby and you know how that goes. Could be 50s or 20s at the surface. The overall "regime" is mild, but I couldn't say where we'll end up. I do lean mild though, but hopefully not too warm.

Funny....I was just thinking to myself last night that I would love to see an overrunning and/or miller b pattern take shape...

[Damage In Tolland]

Euro even though it's a cutter at day10..you can see the confluence to the north and how that might actually trend south and get squashed over subsequent runs

[Damage In Tolland]

Noyes has 40's from Sat thru day 10.

 

Is there still that chance we can still squash that cutter and torch in early Feb.. and get into some overrunning?

[CoastalWx]

Noyes has 40's from Sat thru day 10.

 

Is there still that chance we can still squash that cutter and torch in early Feb.. and get into some overrunning?

 

I still lean mild, but there is always the chance we wedge too.

[googmoog]

I still lean mild, but there is always the chance we wedge too.

Would getting a storm late week have any effect on the size and duration of the torchy period? 

 

I personally think Feb looks aight after a couple days.

[CoastalWx]

Would getting a storm late week have any effect on the size and duration of the torchy period? 

 

I personally think Feb looks aight after a couple days.

 

Big trough carves out in the west, so it should be mild IMO. That cutter does wedge us with mixed precip and/or rain depending on where you are, but regardless it's AN for at least a few days.

[Ginx snewx]

Big trough carves out in the west, so it should be mild IMO. That cutter does wedge us with mixed precip and/or rain depending on where you are, but regardless it's AN for at least a few days.

Jan thaw cometh for a few days

[ORH_wxman]

Regardless of what happens in that Feb 2-3 time period (whether we CAD or torch), the pattern looks really solid after that. Nice PNA ridge building out west.

[CoastalWx]

Regardless of what happens in that Feb 2-3 time period (whether we CAD or torch), the pattern looks really solid after that. Nice PNA ridge building out west.

 

Yep. that hasn't changed. We PNA.

[Isotherm]

Notice that the projected geopotential heights on the ECMWF ensemble mean for early February is an apparent reflection of the stratospheric state. Very strong wave-1 forcing (up to record daily high wave heights actually, around 1700 gpm at 10hpa) will be pushing the 10-70hpa vortex off the pole and toward northern Europe by the beginning of February. We have some bottom-up activity but also the true upper stratospheric perturbation via the wave-1. In response, 500mb heights quickly rise across the pole, forcing the return of the -AO. Depending upon the resolution of the stratospheric event, we may have a period in the first 7-10 days of February in which the AO is negative while contemporaneously the NAO persists in a positive state via the influence of the vortex sitting near NW Europe. As I posted last week, the anomalously strong condition of the vortex may prevent a major SSW, but I think a minor SSW will probably occur in that Jan 30-Feb 4 period. Typically a wave-1 of this extreme amplitude would have no problem inducing a major SSW, but this vortex isn't going down without a fight. Some ensemble members suggest a major SSW, but I'm doubting it right now. The ECMWF on the berlin site nearly reversed the zonal winds at 1 hpa at the beginning of February.

 

Nonetheless, there will be more than sufficient stratospheric perturbation continuing to prevent the resumption of mean +NAM conditions in the troposphere. If we continue to shift that vortex over toward Europe, I would anticipate that modelling becomes more bullish on Greenland geopotential height rises as well.

 

Tropospherically, Pacific +AAM, current GWO state, and location of strongest upper divergence are suggestive of the retrogression of the West Coast trough [Feb 1-2] back into the GOAK/Aleutians for February. Thus, the idea of +PNA / SE US trough is pretty high confidence for February. I think we'll attempt a neutral to potentially -EPO at times; climatologically, stronger Nino's feature their most conducive EPO pattern in February. We'll see. I'm fairly confident we're looking at a favorable PNA / EPO / AO state overall for early February. The NAO, again, may lag due to that vortex presence, but it too should eventually flip back negative.

 

Bottom line, winter, I continue to think, just began snowfall wise in the Northeast.

[Ginx snewx]

Notice that the projected geopotential heights on the ECMWF ensemble mean for early February is an apparent reflection of the stratospheric state. Very strong wave-1 forcing (up to record daily high wave heights actually, around 1700 gpm at 10hpa) will be pushing the 10-70hpa vortex off the pole and toward northern Europe by the beginning of February. We have some bottom-up activity but also the true upper stratospheric perturbation via the wave-1. In response, 500mb heights quickly rise across the pole, forcing the return of the -AO. Depending upon the resolution of the stratospheric event, we may have a period in the first 7-10 days of February in which the AO is negative while contemporaneously the NAO persists in a positive state via the influence of the vortex sitting near NW Europe. As I posted last week, the anomalously strong condition of the vortex may prevent a major SSW, but I think a minor SSW will probably occur in that Jan 30-Feb 4 period. Typically a wave-1 of this extreme amplitude would have no problem inducing a major SSW, but this vortex isn't going down without a fight. Some ensemble members suggest a major SSW, but I'm doubting it right now. The ECMWF on the berlin site nearly reversed the zonal winds at 1 hpa at the beginning of February.

 

Nonetheless, there will be more than sufficient stratospheric perturbation continuing to prevent the resumption of mean +NAM conditions in the troposphere. If we continue to shift that vortex over toward Europe, I would anticipate that modelling becomes more bullish on Greenland geopotential height rises as well.

 

Tropospherically, Pacific +AAM, current GWO state, and location of strongest upper divergence are suggestive of the retrogression of the West Coast trough [Feb 1-2] back into the GOAK/Aleutians for February. Thus, the idea of +PNA / SE US trough is pretty high confidence for February. I think we'll attempt a neutral to potentially -EPO at times; climatologically, stronger Nino's feature their most conducive EPO pattern in February. We'll see. I'm fairly confident we're looking at a favorable PNA / EPO / AO state overall for early February. The NAO, again, may lag due to that vortex presence, but it too should eventually flip back negative.

 

Bottom line, winter, I continue to think, just began snowfall wise in the Northeast.

petty awesome look on the trop by day ten. I am pumped for yet another birthday week snowstorm/near blizzard Feb 6-11th period.

[Isotherm]

petty awesome look on the trop by day ten. I am pumped for yet another birthday week snowstorm/near blizzard Feb 6-11th period.

 

 

 

Yeah, I definitely like the look going forward. I also wouldn’t be surprised to see the Feb 2^nd short wave trend more favorable for you guys in New England. The development of those height rises north of Hudson’s Bay may suggest that the baroclinic zone is shifted southward, but we’ll see. Here's our upcoming wave-1 attack. Whether it results in a technical event remains to be seen, but at the very least, we're significantly perturbing / warming the polar stratosphere.

 

 

[CoastalWx]

The ensembles have warming from AK to Canada. Still doesn't look like a SSW to me since the vortex just moves away and then tries to come back again at the end. It just does not want to go away. Models have been pretty good showing its tenacity.

[Isotherm]

The ensembles have warming from AK to Canada. Still doesn't look like a SSW to me since the vortex just moves away and then tries to come back again at the end. It just does not want to go away. Models have been pretty good showing its tenacity.

 

 

I agree. I don't think we'll have a major SSW this year, though a minor one is still possible. The super charged vortex will be very resistant. Nonetheless, it's still a favorable look for Arctic height rises going forward. Much better to see strong perturbation up there than the monster, symmetrical behemoth sitting on top of the pole w/ a circular wind flow circumnavigating the northern hemisphere.

[mahk_webstah]

I like that WPC has a low passing to our south on Mon-Tues with a coldfront and High pressing down.