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February 2025


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This evening was really nice for a few hours. CT esp looked solid on radar. But I think the mixing in ZR and elevated warm layer despite a cold surface is a sign of things to come.

There looks to be several chances for snow coming up. Maybe we get lucky with a well timed front end thump. But out to 8 or 9 days or so it looks like mixed events at best. People like Walt forecast for the hazards. This evening, the driving was certainly very hazardous despite minor snow accumulations. But most of us are looking for more significant snow to enjoy outdoors. I'm excited for tracking but not yet optimistic for the goods.

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13 hours ago, bluewave said:

There was no real forcing in the 8-1-2 regions. It was mostly In the 4-5 regions. So the +PNA -EPO -AO Niña mismatch pattern was being driven by something else. But it’s possible that the background forcing in 4-5 may have lead to the unfavorable Pacific Jet response. Since Suffolk got 30 inches of snow with a legit MJO 8 back in January 2022. Notice how much more favorable the forcing was closer to and east of the Dateline in January 2022 than in 2025.

 

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While I agree that extratropical (non-MJO) forcing played a significant role in the cold Jan 2025 outcome across the eastern/central US, we need to be careful using VP averaged across an entire month.  Subseasonal variability clearly played a role here. 

In addition, the NCEP reanalysis has some notable biases in VP - it tends to show overly positive VP anomalies near C/S. America and Africa.  See Stanfield et. al 2024, A Climatological Analysis of Upper-Level Velocity Potential Using Global Weather Reanalysis, 1959–2020: https://rmets.onlinelibrary.wiley.com/doi/full/10.1002/joc.8659

The vast majority of the cold anomalies in the eastern/central US occurred in the first two-thirds of Jan.  From around Jan 23 onward it turned warmer than normal.

The Jan 1-10 and Jan 11-20 VP anomalies show -VP anomalies migrating from the central/eastern Pacific and W. Atlantic, to the e. Atlantic and w. Africa.  The magnitude is not as high as the negative anomalies that developed from the eastern IO to Maritime Continent in the Jan 21-31 period.  However, especially in the Jan 11-20 period I would argue the MJO had a significant role, given the coherent wave of -VP (and corresponding +VP across the c/e. Pacific) that developed.

lalogl_jun_hist_chi200_202501.gif

lalogl_jun_hist_chi200_202502.gif

lalogl_jun_hist_chi200_202503.gif

vp.anom.30.5S-5N.gif

VP bias.png

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Good Monday morning everyone, Feb 3. my 2c on what seems to be ensembled ahead.  Planning. Last night was a snow tease here. There's a pretty good chance that between now and March, much of the I84 corridor will see over a foot of snow, possibly 2 feet, Baltimore-Philly-NYC 6-12". Nothing is guaranteed but we're on the northern fringe of a wetter than normal pattern for the next month, with 30 day melted water equivalent probably at least 4" by March 7. Interstate 84 corridor snow depth (ne PA-nw NJ-NYS-CT-MA) will have almost constant snow cover between Feb 6-March 6 (last nights snowfall may melt completely by tomorrow afternoon). 

Patience will be helpful safely and comfortably navigating the multiple weather related hazardous travel delays and cancellations this month into possibly the first week of March. 
 
 
 
 
 

 

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7 hours ago, jconsor said:

While I agree that extratropical (non-MJO) forcing played a significant role in the cold Jan 2025 outcome across the eastern/central US, we need to be careful using VP averaged across an entire month.  Subseasonal variability clearly played a role here. 

In addition, the NCEP reanalysis has some notable biases in VP - it tends to show overly positive VP anomalies near C/S. America and Africa.  See Stanfield et. al 2024, A Climatological Analysis of Upper-Level Velocity Potential Using Global Weather Reanalysis, 1959–2020: https://rmets.onlinelibrary.wiley.com/doi/full/10.1002/joc.8659

The vast majority of the cold anomalies in the eastern/central US occurred in the first two-thirds of Jan.  From around Jan 23 onward it turned warmer than normal.

The Jan 1-10 and Jan 11-20 VP anomalies show -VP anomalies migrating from the central/eastern Pacific and W. Atlantic, to the e. Atlantic and w. Africa.  The magnitude is not as high as the negative anomalies that developed from the eastern IO to Maritime Continent in the Jan 21-31 period.  However, especially in the Jan 11-20 period I would argue the MJO had a significant role, given the coherent wave of -VP (and corresponding +VP across the c/e. Pacific) that developed.

lalogl_jun_hist_chi200_202501.gif

lalogl_jun_hist_chi200_202502.gif

lalogl_jun_hist_chi200_202503.gif

vp.anom.30.5S-5N.gif

VP bias.png

Yeah, my point was that it was more a blend of forcing influences across the tropics rather than one well defined MJO pattern like we have seen in recent winters.

This goes back to my research with the very strong forcing which occurred near the Maritime Continent back in October. The past La Niña cases similarly saw weaker MJO 4-6 activity from December into January with +PNA and -EPO mismatch patterns for La Niña. The opposite was true with weaker MJO 5 October La Niña patterns and then stronger through the winter. So there has been a well defined inverse relationship with the October to winter patterns.

We can see the blend of forcing across the tropics from January 1-20. So we didn’t get the coherent MJO 8 response and 30 inches of snow at Islip which occurred in January 2022. The late January forcing near the Maritime Continent was more the La Niña interseasonal forcing shift which occurs closer to the start of February. This is why the Southeast Ridge typically emerges during La Niña Februaries.


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1 hour ago, wdrag said:

 

Good Monday morning everyone, Feb 3. my 2c on what seems to be ensembled ahead.  Planning. Last night was a snow tease here. There's a pretty good chance that between now and March, much of the I84 corridor will see over a foot of snow, possibly 2 feet, Baltimore-Philly-NYC 6-12". Nothing is guaranteed but we're on the northern fringe of a wetter than normal pattern for the next month, with 30 day melted water equivalent probably at least 4" by March 7. Interstate 84 corridor snow depth (ne PA-nw NJ-NYS-CT-MA) will have almost constant snow cover between Feb 6-March 6 (last nights snowfall may melt completely by tomorrow afternoon). 

Patience will be helpful safely and comfortably navigating the multiple weather related hazardous travel delays and cancellations this month into possibly the first week of March. 
 
 
 
 
 

 

We only received a dusting here - you meant melted by this afternoon ? I wouldn't start any threads yet and the 6Z GFS is nonsense IMO - how many times this winter have we seen this kind of output on the GFS ? Just a couple of days ago it showed this similar solution and the next run it was cut in half or less totals

snku_acc-imp.conus.png

 

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