February 2018 Discussions & Observations Thread

[nzucker]

Nice write-up Isotherm...although I haven't researched as much as you, my concern is that the vortex over Canada looks to be consolidating near Baffin Island instead of weakening and moving towards the United States as was modeled on some of the earlier runs. This supports a strong +NAO pattern, which is unfavorable for large East Coast snowstorms. The position of the Alaska block and associated PAC ridge looks to be extremely far west, as well, which should lead to more of a SWFE or inland runner pattern. 

This may finally be the chance for the I-81 corridor to catch up...but I suspect that, aside from smaller events, NYC's main window does not come until the aforementioned Feb 10-15 period.

[jm1220]

I agree with all of what’s been said regarding the trough axis and stronger storms cutting west until the trough axis can come east, or some blocking develops. The Super Bowl system looks to me to be 1-3” at most, either at the front and end with mostly a washout near the city, or it somehow being weak and sliding SE. This is finally a better pattern for far inland areas that have missed out. 

[CIK62]

Next 8 days averaging 34degs., or 1deg. AN.

[donsutherland1]

Last February was the warmest February on record. The monthly mean temperature was 41.6°, which was 6.3° above normal. The second half of February had a mean temperature of 47.2° and the February 18-25 period had a mean temperature of 52.1°. 36% of days had high temperatures of 50° or above and 21% of days had high temperatures of 60° or above.

February 2018 will likely be different in character. The month should be colder than normal. The 2/10-20/1981-2010 mean temperature for past cases from the forecast teleconnections (EPO-/AO-/PNA+) was 33.2° vs. 35.3° for climatology. The frequency of days with low temperatures below 20° was 35% above climatology. If there is a caveat on the guidance, it is that the EPS has started indicating that an EPO+ with a neutral to positive AO pattern (zonal in character) could develop. Considering the predominant pattern this winter and the forecast MJO progression, I’m not yet sold on this idea, but it will need to be watched.

This month should also be snowier to much snowier than normal across much of the northern Mid-Atlantic and New England areas. The potential for a significant to major snowstorm will be higher than the climatological probability during the second or third week of February as the MJO moves through Phases 8 and 1 coupled with an AO-/PNA+ pattern. This is where the EPS has shifted dramatically to a milder zonal pattern.

Albany, which had a nearly 10” seasonal snowfall deficit could be near or even above normal in seasonal snowfall by the end of the month. Cities such as Bridgeport, Islip, New York, Newark, and Philadelphia should have even larger positive seasonal snowfall anomalies by the end of the month.

For NYC, my thinking remains as follows: Monthly mean temperature: 34.0° +/- 0.5°; Monthly snowfall: 12”-18” (potential for more than 20” exists). 

New York City’s Average Temperature Through:

2/5 30.2°-35.0°
2/10 30.2°-35.6°

Per aggressive sensitivity analysis, the estimated probability of a below normal monthly anomaly: 50% (50.3%)

[weatherpruf]

40 minutes ago, donsutherland1 said:

Last February was the warmest February on record. The monthly mean temperature was 41.6°, which was 6.3° above normal. The second half of February had a mean temperature of 47.2° and the February 18-25 period had a mean temperature of 52.1°. 36% of days had high temperatures of 50° or above and 21% of days had high temperatures of 60° or above.

February 2018 will likely be different in character. The month should be colder than normal. The 2/10-20/1981-2010 mean temperature for past cases from the forecast teleconnections (EPO-/AO-/PNA+) was 33.2° vs. 35.3° for climatology. The frequency of days with low temperatures below 20° was 35% above climatology. If there is a caveat on the guidance, it is that the EPS has started indicating that an EPO+ with a neutral to positive AO pattern (zonal in character) could develop. Considering the predominant pattern this winter and the forecast MJO progression, I’m not yet sold on this idea, but it will need to be watched.

This month should also be snowier to much snowier than normal across much of the northern Mid-Atlantic and New England areas. The potential for a significant to major snowstorm will be higher than the climatological probability during the second or third week of February as the MJO moves through Phases 8 and 1 coupled with an AO-/PNA+ pattern. This is where the EPS has shifted dramatically to a milder zonal pattern.

Albany, which had a nearly 10” seasonal snowfall deficit could be near or even above normal in seasonal snowfall by the end of the month. Cities such as Bridgeport, Islip, New York, Newark, and Philadelphia should have even larger positive seasonal snowfall anomalies by the end of the month.

For NYC, my thinking remains as follows: Monthly mean temperature: 34.0° +/- 0.5°; Monthly snowfall: 12”-18” (potential for more than 20” exists). 

New York City’s Average Temperature Through:

2/5 30.2°-35.0°
2/10 30.2°-35.6°

Per aggressive sensitivity analysis, the estimated probability of a below normal monthly anomaly: 50% (50.3%)

Thanks Don good write up. But based on some other posters here I'm prepared for a lot of Feb to be a dud. Hope it works out for us.

[bluewave]

You can really see why the models are correcting stronger with the ridge off the East Coast during this first week of February. The MJO just set the record for the strongest phase 6 amplitude since 1979. It remains to be seen how this new extreme for this winter impacts later forecasts. 

 

Prelim data shows highest amplitude MJO event on record (back to 1979) over the West Pacific. Wow! #MJO #ClimateSmart pic.twitter.com/k3i9TrOH7c

12:16 PM - 31 Jan 2018

 

 

 

 

[qg_omega]

9 minutes ago, bluewave said:

You can really see why the models are correcting stronger with the ridge off the East Coast during this first week of February. The MJO just set the record for the strongest phase 6 amplitude since 1979. It remains to be seen how this new extreme for this winter impacts later forecasts. 

 

Prelim data shows highest amplitude MJO event on record (back to 1979) over the West Pacific. Wow! #MJO #ClimateSmart pic.twitter.com/k3i9TrOH7c

12:16 PM - 31 Jan 2018

 

 

 

 

Amazing long Island just had a SECS with the MJO in record phase 6.  This year will be remembered as the Suffolk county winter.

[LurkerBoy]

Just saw the EPS looks super ugly in the 11-15. Pattern breakdown. Uh oh!

[bluewave]

29 minutes ago, qg_omega said:

Amazing long Island just had a SECS with the MJO in record phase 6.  This year will be remembered as the Suffolk county winter.

Just goes to show what a near record +550 meter block over Eastern Siberia can do even in an otherwise challenging pattern. Unfortunately, that feature will be rapidly weakening over the weekend. 

[EastonSN+]

3 minutes ago, bluewave said:

Just goes to show what a near record +550 meter block over Eastern Siberia can do even in an otherwise challenging pattern. Unfortunately, that feature will be rapidly weakening over the weekend. 

Hey Bluwave. What are your thoughts for the remainder of winter? Do you believe that the coast will experience one last good period in terms of snowfall, or has the latest guidance pretty much sealed our fate barring a freak event?

Also is this change based solely on the mjo getting stuck in phase 7?

[SnoSki14]

The MJO has been an excellent indicator of our pattern this winter so once it gets into phase 8-1, I'm inclined to believe it'll result in a favorable pattern for us. 

The record phase 6 amplitude suggests we'll get there by mid Feb.

[donsutherland1]

3 hours ago, weatherpruf said:

Thanks Don good write up. But based on some other posters here I'm prepared for a lot of Feb to be a dud. Hope it works out for us.

It’s too soon to know whether there is a disconnect between the forecast 500 mb maps and the forecast teleconnections. One factor that could produce such an outcome is the dramatic relaxation in the trade winds that has occurred in recent days with the SOI have gone negative. The ensembles are divided between those that take the MJO into Phase 8 and those that lock it in Phase 7 through 2/14. The EPS is among the ensemble members that lock the MJO in Phase 7. 7-day or longer periods that commenced prior to 2/10 and continued into part of February are fairly uncommon (6 cases since 1975)

Long Duration MJO Phase 7 (commenced prior to 2/10):

2/6-16/1980 11 days
1/28-2/5/1986 9 days
2/1-16/1989 16 days
1/30-2/10/1993 12 days
2/7-14/2005 7 days
1/22-2/6/2010 16 days

Cases where the AO averaged < 0 during the MJO Phase 7 periods from the above cases:

1980 -1.602 Mean NYC Temperature: 31.9°
1986: -2.971 Mean NYC Temperature: 30.7°
2010: -2.526 Mean NYC Temperature: 32.4°

Cases where the PNA averaged > 0 during the MJO Phase 7 periods from the above cases:

1980 +1.259 Mean NYC Temperature: 31.9°
1986: +1.055 Mean NYC Temperature: 30.7°
1993: +0.782 Mean NYC Temperature: 32.0°
2005: +0.298 Mean NYC Temperature: 40.7°
2010: +0.265 Mean NYC Temperature: 32.4°

Cases not meeting either criterion:

1989: Mean NYC Temperature: 34.9°

Considering the forecast teleconnections, limited cases with long-duration MJO Phase 7 and AO- or PNA+, the EPS weekly and monthly forecasts, and the CFSv2 monthly forecast, I’m not yet sold on the dramatic shift that has taken place on the EPS over the past two days. This could be a temporary situation, much as the GEFS suddenly lost the idea of an extended period of cold beginning in later December for a time.  So, at least at this point in time, I’m not ready to throw out my thinking on February.

Of course, extended range forecasting is subject to high uncertainty and high risk of error.

[uncle W]

18 minutes ago, donsutherland1 said:

It’s too soon to know whether there is a disconnect between the forecast 500 mb maps and the forecast teleconnections. One factor that could produce such an outcome is the dramatic relaxation in the trade winds that has occurred in recent days with the SOI have gone negative. The ensembles are divided between those that take the MJO into Phase 8 and those that lock it in Phase 7 through 2/14. The EPS is among the ensemble members that lock the MJO in Phase 7. 7-day or longer periods that commenced prior to 2/10 and continued into part of February are fairly uncommon (6 cases since 1975)

Long Duration MJO Phase 7 (commenced prior to 2/10):

2/6-16/1980 11 days
1/28-2/5/1986 9 days
2/1-16/1989 16 days
1/30-2/10/1993 12 days
2/7-14/2005 7 days
1/22-2/6/2010 16 days

Cases where the AO averaged < 0 during the MJO Phase 7 periods from the above cases:

1980 -1.602 Mean NYC Temperature: 31.9°
1986: -2.971 Mean NYC Temperature: 30.7°
2010: -2.526 Mean NYC Temperature: 32.4°

Cases where the PNA averaged > 0 during the MJO Phase 7 periods from the above cases:

1980 +1.259 Mean NYC Temperature: 31.9°
1986: +1.055 Mean NYC Temperature: 30.7°
1993: +0.782 Mean NYC Temperature: 32.0°
2005: +0.298 Mean NYC Temperature: 40.7°
2010: +0.265 Mean NYC Temperature: 32.4°

Cases not meeting either criterion:

1989: Mean NYC Temperature: 34.9°

Considering the forecast teleconnections, limited cases with long-duration MJO Phase 7 and AO- or PNA+, the EPS weekly and monthly forecasts, and the CFSv2 monthly forecast, I’m not yet sold on the dramatic shift that has taken place on the EPS over the past two days. This could be a temporary situation, much as the GEFS suddenly lost the idea of an extended period of cold beginning in later December for a time.  So, at least at this point in time, I’m not ready to throw out my thinking on February.

Of course, extended range forecasting is subject to high uncertainty and high risk of error.

to bad the nao is forecast to stay around a plus one for the period...1986 saw two 4" snowfalls just after the period shown...in 1993 winter took a turn for the better after the period shown...

[EastonSN+]

This has me spooked the most Don and Audience. EPO keeps trending less negative:

 

[snywx]

6 hours ago, Animal said:

Morning afd from mt Holly  nws is calling for an all snow event Sunday into Monday morning nw zones. “Decent dump of snow” is the term used.

Upton:

SW flow sets up aloft Saturday night, with low level warm advection
bringing some spotty light snow to mainly the NW 1/2 of the CWA late
Saturday night. A 700-500 hPa shortwave coupled with increasing
isentropic ascent will produce more widespread precipitation on
Sunday, especially in the afternoon. A 700-500 hPa trough then
approaches Sunday night then lifts to the NE on Monday. This will
help drive the intensification of a coastal low of the Mid Atlantic
Coast Sunday night. This coastal low tracks SE of Long Island, but
probably inside the 40N/70W benchmark Sunday night, before lifting
NE on Monday. There is some uncertainty on this timing, with some
suggestion that things might occur 6 hours or so faster than
current forecast.

In terms of sensible weather Sunday-Monday morning. Will see
precipitation change from snow to a wintry mix across the interior
and from snow to rain elsewhere. There are then differences in how
quickly low level cold air returns Sunday night. For now keep
transitions back to all snow across mainly far northern portions of
interior zones Sunday night, with a wintry mix possible across the
remainder of the northern/far western zones - with NYC/Long
Island/Coastal SE CT staying all rain. Precipitation ends on Monday
morning, as snow across interior zones/coastal SW CT zones. A wintry
mix over E NE NJ/into NYC and as plain rain over Long Island/coastal
SE CT. For now to early to specify amounts, but there is some
potential for an advisory level to possibly a warning level snowfall
across mainly northern interior zones from Sunday into Monday
morning. Will address this potential in the HWO.

[CPcantmeasuresnow]

The chart above summarizes the monthly and seasonal snowfall averages in New York City over different periods of time.

The first line reflects the historical averages from January 1869 through January 2018. Through the almost 150 years records have been kept the seasonal snowfall averages 28.9 inches per season.

The second line reflects the number most people would see now on websites or on the weather Channel which is the 30 year average. For those that don't know how these are calculated, NOAA updates these averages every 10 years. The next update will be in January 2021.

If you look on any websites the average will show 25.8 inches. The reason for the discrepancy is NOAA has a 7.0 figure for January when the actual calculated average is 7.1. They originally calculated 25.1 inches for the season, but in March 2014 they finally relented and admitted their mistake and updated the totals accordingly. I've told that story several times I won't bore anyone with the details again.

The third line which I find the most interesting is the average right now from January 1991 through this past January. This will be the time period NOAA uses for the new 30 year averages when they are calculated in three years. As you can see the seasonal average stands to jump almost 5 inches per year to 30.8 inches which is what New York City has averaged the last 27 years and one month.

The next two lines are the averages from January 2001 to the present which is a robust 33.9 inches, and January 2011 to the present which is 35.6 inches. The last line shows what the new 30 year average would be for 1991-2020, should God forbid no snow fall for the next two years and 11 months, which is 28.0 inches.

There are several things of note here but the most pronounced is the increased amounts of the averages in the months of January and February. Even as compared to their 150 year averages January and February are seeing a nice spike in the last 30 years most notably in the last 20.

Uncle W posted similar stats in a different format several days ago, we just use different beginning dates which is why there will be some variations between the two averages. I'm using periods that are used to calculate thirty-year averages which begin in January of the one numbered year of any decade. I believe uncle W posted his figures doing it for the number decade itself so the 90s would be 1990 to 1999. For my purposes they would be January 1991 through December 2000.

[MJO812]

6 hours ago, EastonSN+ said:

This has me spooked the most Don and Audience. EPO keeps trending less negative:

 

But the PNA and AO are trending favorable

[PB COLTS NECK NJ]

Don't look at the weeklies.

[LongBeachSurfFreak]

46 minutes ago, PB COLTS NECK NJ said:

Don't look at the weeklies.

Big bust potential for allot of us. I’m not saying that’s how it goes down but it cannot be discounted 

[PB COLTS NECK NJ]

14 minutes ago, LongBeachSurfFreak said:

Big bust potential for allot of us. I’m not saying that’s how it goes down but it cannot be discounted 

Agree on both counts 

[weatherpruf]

29 minutes ago, PB COLTS NECK NJ said:

Agree on both counts 

Gives me pause. I believe my area was short of average snowfall last winter; if things go south we will come up short again. It happens and I have seen it before, sometimes back to back like this.

[WEATHERBUFF]

51 minutes ago, PB COLTS NECK NJ said:

Agree on both counts 

Luckily the weeklies have been not that good!

[donsutherland1]

2 hours ago, PB COLTS NECK NJ said:

Don't look at the weeklies.

The shift is about as big as it can get.

[PB COLTS NECK NJ]

12 minutes ago, donsutherland1 said:

The shift is about as big as it can get.

Don, last week it forecast a solid  6 weeks of deep winter , tonight it dropped spring in after the 10th.

I agree , that's as big a flip as you get.

[PB COLTS NECK NJ]

22 minutes ago, WEATHERBUFF said:

Luckily the weeklies have been not that good!

 

They have been very bad,  busted,  flipped etc.

But the Euro flipped on it's ensembles last night and continued today.

Not a good look if one was counting on a good FEB. Ahem.....

[donsutherland1]

12 minutes ago, PB COLTS NECK NJ said:

Don, last week it forecast a solid  6 weeks of deep winter , tonight it dropped spring in after the 10th.

I agree , that's as big a flip as you get.

Either a dramatic pattern change could occur in the medium term, or they are struggling with a complex pattern evolution (possibly related to the decay in the La Niña and recent weakening of the trade winds). Next week's run could be crucial.

[PB COLTS NECK NJ]

7 minutes ago, donsutherland1 said:

Either a dramatic pattern change could occur in the medium term, or they are struggling with a complex pattern evolution (possibly related to the decay in the La Niña and recent weakening of the trade winds). Next week's run could be crucial.

I guess we will know in a few days and the key changes to look for will out in the EPAC and W Canada by day 10.

[donsutherland1]

51 minutes ago, PB COLTS NECK NJ said:

I guess we will know in a few days and the key changes to look for will out in the EPAC and W Canada by day 10.

I agree.

[Rjay]

2 hours ago, donsutherland1 said:

The shift is about as big as it can get.

Thank god I didnt end up goimg super cold in the temp contest.  The weeklies look flat out ugly. 

[RU848789]

6 hours ago, weatherpruf said:

Gives me pause. I believe my area was short of average snowfall last winter; if things go south we will come up short again. It happens and I have seen it before, sometimes back to back like this.

Well, I got 29.5" in Metuchen last winter, so unlikely you'd have been below normal 3-4 miles to my NE.