February 10-12 Potential

[earthlight]

Despite the recent snap reactions by many to jump ship and panic over short range model data -- the time period which was laid out by several forecasters a few weeks ago continues to look relatively favorable. February 10-12 was a rough estimate used by many as a time period where things could align correctly for us to potentially cash in on a snow event.

What I wanted to straighten out -- and this is something I think has been lost in the past few days -- is that the last week of January into the 1st week/weekend of February was never forecast to be favorable. Even a few days ago we spoke about how the ridge alignment was bad with a buldge to the east (eventually forced a cutoff low over the Central US). This is a horrible airmass with stale cold -- but the promise of something better does exist around the 8th of the month and moving forward.

The Euro ensembles and, much more convincingly, the GFS Ensembles have a good signal for a potential event next weekend. Obviously we are still, at best, monitoring the potential as plenty can change in the medium range. But the general patern has been laid out for us..with the MJO forecast to be more favorable than it has been yet this winter season. A split flow underneath a big ridge out west extending into British Columbia is a good signal for some southern stream moisture and energy -- and maybe some overrunning precipitation? You can see on the GEFS means that there is very good agreement for Polar air to be situated just north of us in Southeast Canada...thanks to above normal height anomalies from British Columbia to the poles and even towards Western Greenland and northwest Baffin Island.

We'll see how this all plays out...but I think the "ceiling" for this event is more than likely higher than anything we've seen yet this winter. If we can get the PV involved things could get really interesting. But we need to keep the PNA ridge axis as it is on the models....if we move it any farther east or de-amplify it (or if we lose the high latitude ridging signal) we'll be playing with fire again and the potential to exit this favorable period empty handed.

[Isotherm]

John, I think much of the difference we're currently seeing b/t the ECMWF and GFS D 7+ proggs is due to the disparity in tropical forcing forecasts.

The GFS is very bullish in taking this wave through octant 7-8 and into 1, which would translate to the cold pattern being depicted on GFS based guidance.

However, the ECMWF MJO outlook is much more depressing w/ a dying wave once into phase 8, which doesn't help us at all.

After the pattern of the past couple months, I'm not willing to get excited, until (IF) the ECMWF trends toward the GFS with its MJO forecast. If the MJO wave dies, we may not see anything out of this mid feb period.

With that being said, if there is going to be a decent snow event, the Feb 10th-20th period has potential as we've discussed for the past couple weeks. If the GFS MJO depiction is correct, I'm actually more interested when the wave gets to latter phase 8 and into phase 1, which would be closer to the 15th, but we'll see. First things first - let's see if we can get some continuity b/t the Euro and GFS on MJO outlooks. As it stands now, I'm not too excited, but it is nice to see the GFS taking the MJO through 8/1 which it hasn't forecasted so far this winter.

[uncle W]

analogs like 1950, 1975, 2006 had a snowstorm between the 11-13th...1950's storm was 4" but it eventually turned to rain...1975's storm was almost 8" and 2006 was the largest measured snowfall of all time...If we get an event I would think it would be similar to 1950...

[NYCSuburbs]

I know it's probably useless to complain when we actually have the potential to see snow in this terrible winter, but would we want the trough to dig further south than the GEFS shows? There definitely is potential here with the much better set up but it's still far from ideal and could go wrong just as almost all of the handful of potentials we had this winter have.

[CooL]

I know it's probably useless to complain when we actually have the potential to see snow in this terrible winter, but would we want the trough to dig further south than the GEFS shows? There definitely is potential here with the much better set up but it's still far from ideal and could go wrong just as almost all of the handful of potentials we had this winter have.

The map posted is an ensemble mean map. Several show a large storm during the period, several show nothing. So its basically an average anamoly map

[earthlight]

John, I think much of the difference we're currently seeing b/t the ECMWF and GFS D 7+ proggs is due to the disparity in tropical forcing forecasts.

The GFS is very bullish in taking this wave through octant 7-8 and into 1, which would translate to the cold pattern being depicted on GFS based guidance.

However, the ECMWF MJO outlook is much more depressing w/ a dying wave once into phase 8, which doesn't help us at all.

After the pattern of the past couple months, I'm not willing to get excited, until (IF) the ECMWF trends toward the GFS with its MJO forecast. If the MJO wave dies, we may not see anything out of this mid feb period.

With that being said, if there is going to be a decent snow event, the Feb 10th-20th period has potential as we've discussed for the past couple weeks. If the GFS MJO depiction is correct, I'm actually more interested when the wave gets to latter phase 8 and into phase 1, which would be closer to the 15th, but we'll see. First things first - let's see if we can get some continuity b/t the Euro and GFS on MJO outlooks. As it stands now, I'm not too excited, but it is nice to see the GFS taking the MJO through 8/1 which it hasn't forecasted so far this winter.

Nice post Tom and I agree with all of your thoughts. The tropical forcing forecasts have been highly unstable this season. Interestingly enough i've noticed the ECMWF has had a tendency to be too weak with the waves so far. I'm not sure if there is any statistical data somewhere on this...but it's definitely something I have picked up on over the past few months of forecasting.

The pattern laid out on the GFS and GEFS is a very interesting one. There's a split flow underneath the ridge out west and a generally well-positioned PV signal. It's not too far south yet so that it would suppress the upper level flow...and it's also not too far north so that it could work against us. Obviously the positioning of this becomes key and a lot of that works in tandem with the higher latitude ridging or above normal anomalies we're seeing on some of the ensemble guidance.

We will have to see how this plays out...I really don't think we know all the details on the synoptics of this one yet. But as advertised it looks interesting with some well positioned features. I really like the look of the broad trough coming out of the southern stream. When the PV is well positioned it loves to get involved and interact with those types of features.

The other option on the table here is that the southern stream trough never really ejects out of it's comfortable position. In that case the PV will swing through and that'll be that. We will see.

[blizzardof09]

The map posted is an ensemble mean map. Several show a large storm during the period, several show nothing. So its basically an average anamoly map

we get that southern stream to merge with that northern stream at the right time next week/weekend we'll be in business. we are for sure more favorable now than at any other part of the winter. its gonna be timing and that pacific trough and how it sets up. im an amatuer still so any problems with this response let me know. thanks

[Alpha5]

H5 is certainly becoming more favorable for east coast snow, and it looks like that is almost completely driven by the major MJO wave propagating through phase 7.

We just need something to pop for us

[NYCSuburbs]

H5 is certainly becoming more favorable for east coast snow, and it looks like that is almost completely driven by the major MJO wave propagating through phase 7.

We just need something to pop for us

This set up could very possibly be the best the pattern gets this winter, with a well timed western ridge along with a trough in the East and a temporarily displaced PV in Canada. This already looks better than the temporary change in the middle of January which looked good for maybe a day or two before falling apart, and even that brought a moderate snow event. It could just be cold and dry with no storm developing, but if a storm is to take advantage of the pattern and finally produce something, this could be it.

[Isotherm]

Nice post Tom and I agree with all of your thoughts. The tropical forcing forecasts have been highly unstable this season. Interestingly enough i've noticed the ECMWF has had a tendency to be too weak with the waves so far. I'm not sure if there is any statistical data somewhere on this...but it's definitely something I have picked up on over the past few months of forecasting.

The pattern laid out on the GFS and GEFS is a very interesting one. There's a split flow underneath the ridge out west and a generally well-positioned PV signal. It's not too far south yet so that it would suppress the upper level flow...and it's also not too far north so that it could work against us. Obviously the positioning of this becomes key and a lot of that works in tandem with the higher latitude ridging or above normal anomalies we're seeing on some of the ensemble guidance.

We will have to see how this plays out...I really don't think we know all the details on the synoptics of this one yet. But as advertised it looks interesting with some well positioned features. I really like the look of the broad trough coming out of the southern stream. When the PV is well positioned it loves to get involved and interact with those types of features.

The other option on the table here is that the southern stream trough never really ejects out of it's comfortable position. In that case the PV will swing through and that'll be that. We will see.

Thanks John, and nice follow up post as well. No doubt the GFS/GEFS will make any weenie foam at the mouth; I hope it verifies, but a lot depends on this MJO wave progression especially since we're not likely to see any meaningful north atlantic block develop. We're seeing the results of a -2 SD AO right now, and ensemble guidance has the AO trending slightly more positive over the next couple weeks (although still negative). If we don't get the MJO induced ridge pumping on the west coast, we're bound to revert to (or should I say continue) the same warmer than normal pattern.

As you noted, even if the GFS/GEFS plays out, there's a chance we remain cold/dry, depending upon s/w timing and phasing. But those issues will be examined once we're more certain the pattern depicted on the GFS will come to fruition.

[earthlight]

Thanks John, and nice follow up post as well. No doubt the GFS/GEFS will make any weenie foam at the mouth; I hope it verifies, but a lot depends on this MJO wave progression especially since we're not likely to see any meaningful north atlantic block develop. We're seeing the results of a -2 SD AO right now, and ensemble guidance has the AO trending slightly more positive over the next couple weeks (although still negative). If we don't get the MJO induced ridge pumping on the west coast, we're bound to revert to (or should I say continue) the same warmer than normal pattern.

As you noted, even if the GFS/GEFS plays out, there's a chance we remain cold/dry, depending upon s/w timing and phasing. But those issues will be examined once we're more certain the pattern depicted on the GFS will come to fruition.

Part of the reason I think this has some legs is because the Scandanavian ridging /part of the - AO/ pretty much teams up with the ridge over British Columbia which blocks up the pole and parts of the West NAO area. It's a complicated set up but it's also really cool to see and should be a nice view for those who doubted that the stratospheric warming was legitimate. If you run your mouse over the ensemble mean height anomaly link below..you can see how it all transpires. Directly prior to the ridge connection, around 96 hours, some Polar air crosses the pole. So we've got a psuedo-PV over Southeast Canada which is locked there by the ridging around 150 hrs. This is a great set up for something if we can get the split flow shortwave to eject some energy eastward. If not, it will go to waste as the PNA ridge collapses and all those anomalies build towards the Pole.

http://www.meteo.psu...nsloopmref.html

[Isotherm]

Part of the reason I think this has some legs is because the Scandanavian ridging /part of the - AO/ pretty much teams up with the ridge over British Columbia which blocks up the pole and parts of the West NAO area. It's a complicated set up but it's also really cool to see and should be a nice view for those who doubted that the stratospheric warming was legitimate. If you run your mouse over the ensemble mean height anomaly link below..you can see how it all transpires. Directly prior to the ridge connection, around 96 hours, some Polar air crosses the pole. So we've got a psuedo-PV over Southeast Canada which is locked there by the ridging around 150 hrs. This is a great set up for something if we can get the split flow shortwave to eject some energy eastward. If not, it will go to waste as the PNA ridge collapses and all those anomalies build towards the Pole.

http://www.meteo.psu...nsloopmref.html

Good points, and I agree, the PNA ridge connection across the top of the globe is key in terms of getting some real cold air into Canada. If it plays out as depicted on the GFS, that's a very favorable pattern for the Northeast US.

Also agree that there's no doubt the stratospheric warming had/is having its effect. Many think that b/c we haven't turned cold, the stratospheric warming didn't do anything. But we saw the AO reversal mid January as both of us had been talking about, except the block oriented itself on the other side of the pole, providing Asia and now Europe with arctic (some cases record breaking) air. We've gotten unlucky every step of the way this winter. Will we the next few weeks? Come back in a few days and I think we'll have a better clue on the MJO.

[earthlight]

Also interesting to note that the Euro medium-range ensemble is leaning much more towards the NCEP medium-range guidance than the operational Euro itself. We'll have to see if this is a tip-off that the OP Euro's MJO wave depiction is incorrect.

[earthlight]

One last link...here's a glimpse of how horrible the tropical forcing forecasts have been this year. This is the medium-range Euro forecast from Jan 27

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/CLIVAR/EMON_phase_51m_small.gif

Now see the bold black dot for where the MJO was observed today. Not one ensemble member was correct from just 3-4 days ago.

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/CLIVAR/NCPE_phase_21m_small.gif

[Isotherm]

Yeah, abysmal MJO forecasting this year, which is why at this point I'd go w/ pattern persistance (tendency for MJO to die) until we see more agreement b/t models and get closer to the time frame.

[Weathergun]

One last link...here's a glimpse of how horrible the tropical forcing forecasts have been this year. This is the medium-range Euro forecast from Jan 27

http://www.cpc.ncep....e_51m_small.gif

Now see the bold black dot for where the MJO was observed today. Not one ensemble member was correct from just 3-4 days ago.

http://www.cpc.ncep....e_21m_small.gif

IMO, the GEFS has been awful compared to the ECMWF ensemble MJO forecasts, this winter. Especially out the one to the 15 days. The GEFS has it favorable phases in early December and than again in first half of Janaury. The GEFS bias corrected forecast is for a weaker MJO than actual forecast. While the ECMWF based on climo is little stronger and the UKME is pretty close to that too. So I think we something closer to those two models, which wouldn't be bad.

[jiksports]

Storm is way south on the GFS.

[Dark Energy]

Nice post Tom and I agree with all of your thoughts. The tropical forcing forecasts have been highly unstable this season. Interestingly enough i've noticed the ECMWF has had a tendency to be too weak with the waves so far. I'm not sure if there is any statistical data somewhere on this...but it's definitely something I have picked up on over the past few months of forecasting.

The pattern laid out on the GFS and GEFS is a very interesting one. There's a split flow underneath the ridge out west and a generally well-positioned PV signal. It's not too far south yet so that it would suppress the upper level flow...and it's also not too far north so that it could work against us. Obviously the positioning of this becomes key and a lot of that works in tandem with the higher latitude ridging or above normal anomalies we're seeing on some of the ensemble guidance.

We will have to see how this plays out...I really don't think we know all the details on the synoptics of this one yet. But as advertised it looks interesting with some well positioned features. I really like the look of the broad trough coming out of the southern stream. When the PV is well positioned it loves to get involved and interact with those types of features.

The other option on the table here is that the southern stream trough never really ejects out of it's comfortable position. In that case the PV will swing through and that'll be that. We will see.

I saw this yest and was interested. We'll see how it goes.

[Isotherm]

Today's MJO forecasts indicate no improvement in continuity. The ECMWF continues to kill off the wave shortly after entering p8 while the GFS takes it into p1. As I said yesterday, given pattern persistance/progression so far this winter, I'm finding it difficult to buy into the GFS's very strong MJO wave. With that said, we will make it into phase 8 (at least low amplitude), which ultimately should cool off the Eastern US for a temporary period. Still the period Feb 10-20 is probably our best shot of the winter thus far, given we haven't made it to phase 8 MJO all season, so maybe we can pull off a 3"+ event in this period. Not a very good pattern in my opinion, but one that has the potential to produce a light to moderate event given a -AO, PNA pulse and more conducive tropical forcing (temporarily at least).

[NorEaster27]

Today's MJO forecasts indicate no improvement in continuity. The ECMWF continues to kill off the wave shortly after entering p8 while the GFS takes it into p1. As I said yesterday, given pattern persistance/progression so far this winter, I'm finding it difficult to buy into the GFS's very strong MJO wave. With that said, we will make it into phase 8 (at least low amplitude), which ultimately should cool off the Eastern US for a temporary period. Still the period Feb 10-20 is probably our best shot of the winter thus far, given we haven't made it to phase 8 MJO all season, so maybe we can pull off a 3"+ event in this period. Not a very good pattern in my opinion, but one that has the potential to produce a light to moderate event given a -AO, PNA pulse and more conducive tropical forcing (temporarily at least).

Agreed with the ECMWF MJO forecast, no chance of the GFS coming close to verifying. Actually the NCEP suite did make a huge step toward the ECMWF with the hard turn toward the COD in phase 8.

[Weathergun]

Agreed with the ECMWF MJO forecast, no chance of the GFS coming close to verifying. Actually the NCEP suite did make a huge step toward the ECMWF with the hard turn toward the COD in phase 8.

I agree. And I expect it to continue correct towards a weaker MJO signal. Our best hope is that ECMM and UKME forecasts are correct. As they don't have MJO weakening as much between phases 7 and 8 as the ECMF.

[jiksports]

12Z GFS is back North with the storm. It brings rain to the coast, snow inland.

[mattinpa]

12Z GFS is back North with the storm.  It brings rain to the coast, snow inland.

The track is terrific; still have a long way to go with this one.

[NEG NAO]

12Z GFS is back North with the storm. It brings rain to the coast, snow inland.

Storm is closer - cold air on is not phasing with the storm - hard to believe

http://raleighwx.ame...bTSLPp12192.gif

[jiksports]

The track is terrific; still have a long way to go with this one.

Yeah especially for those of us in PA/Upstate NY. NYC is gonna need some more cold air though.

[SnoSki14]

And there's so much cold air to the north, the PV extends to the lower Hudson. Only this winter would we get screwed by a perfect track, oh well it's just one run 8 days out.

[Kaner587]

12Z GFS is back North with the storm. It brings rain to the coast, snow inland.

The problem with this storm as modeled by the GFS is that it is purely southern stream. There is a fresh high pressure comign in but it is relatively weak. There is ample moisture for sure but a lack of antecedent cold air and even cold air being entrenched into the storm since there is very little northern stream interaction. If we could get a consolidated s/w from the northern stream (which is defnitely a possibility since s/w have been rotating around the very powerful PV sitting in central/northern Canada) to dive into this bad boy we could be in luck. We'll see what the EURO/UKIE/GGEM have to say about it.

[SnoSki14]

It's really a shame we don't have even a little bit more blocking. It could have forced the PV further south, bringing much colder air and it would phase beautifully with that very moist and strong southern stream system right up the coast similar to the gfs depiction but a lot colder and the storm much stronger.

[CooL]

It's really a shame we don't have even a little bit more blocking. It could have forced the PV further south, bringing much colder air and it would phase beautifully with that very moist and strong southern stream system right up the coast similar to the gfs depiction but a lot colder and the storm much stronger.

i don't think we'd want the PV further south, it would probably suppress it. But like KAner said, if we could get a northern stream s/w to break off and phase with the boatload of energy in the south we could be in business

[MJO812]

At least the GFS is showing a storm .Details should be worked on as we get closer.