January 2018 Discussions & Observations Thread

[Isotherm]

Weeklies remain steadfast with the idea that the second week of February is the inflection point, congruous with my thoughts. It's a warm to occasionally torch pattern prior to then. My primary question at this point is whether there will be NAO participation in the more auspicious pattern; that will likely be a function of the stratospheric evolution, still a bit indeterminate right now. Will know more in about a week. The vortex will receive some hard hits in early Feb via wave 2 amplification. At the very least, a weakening SPV is expected. Sometime in the second week of February through early March should yield a sustained wintry pattern.

[frd]

9 minutes ago, Isotherm said:

Weeklies remain steadfast with the idea that the second week of February is the inflection point, congruous with my thoughts. It's a warm to occasionally torch pattern prior to then. My primary question at this point is whether there will be NAO participation in the more auspicious pattern; that will likely be a function of the stratospheric evolution, still a bit indeterminate right now. Will know more in about a week. The vortex will receive some hard hits in early Feb via wave 2 amplification. At the very least, a weakening SPV is expected. Sometime in the second week of February through early March should yield a sustained wintry pattern.

@Isotherm do you think there is any carry over from the early Jan prescursor pattern that sometimes precedes SSWE?

Or, are there differant mechanisms at work at the end of Jan and early Feb? ( ie. wave breaking ) 

I also read that as the PV becomes elongated it becomes more susceptable to ozone . I also read that presently ozone concentrations are low.  So many differant aspects to think about. Not to jinx your forecast :-)  but your weather progression looks good so far according to the ECM weeklies and other longer range tools as well.      

 

[Isotherm]

1 hour ago, frd said:

@Isotherm do you think there is any carry over from the early Jan prescursor pattern that sometimes precedes SSWE?

Or, are there differant mechanisms at work at the end of Jan and early Feb? ( ie. wave breaking ) 

I also read that as the PV becomes elongated it becomes more susceptable to ozone . I also read that presently ozone concentrations are low.  So many differant aspects to think about. Not to jinx your forecast :-)  but your weather progression looks good so far according to the ECM weeklies and other longer range tools as well.      

 

@frd - I would say, yes, definitely. The potent wave-1 event this month (peaking now) has induced a significant deceleration in zonal winds and thus SPV intensity. It will attempt to recover back to near normal levels thereafter, but nowhere near the prior stronger than normal strength. Depending upon the eventual potency of wave-2 activity down the road, this would further weaken a vortex in an already more susceptible state. The resultant effects of any follow up wave 2 probably wouldn't manifest until mid February as far as significant modulation of the AO/NAO domains. As the MJO propagates eastward, this will tend to increase trop-strat RW driving as well by early Feb. You are correct that ozone is well below normal right now, particularly on the AO/NAO side, which coincides nicely with the persistent/interminable low geopotential height signal near Greenland. That is also correct that elongation of the vortex via vertically propagating waves will promote increased ozone intrusion.

[SnoSki14]

13 hours ago, donsutherland1 said:

The idea that the second half of the January thaw, which has seen some interruptions, would feature the longest period of sustained warmer than normal anomalies still appears on course. Around a week ago, I had some concern based on 500 mb pattern recognition that the AO could turn positive (this was a separate development from the nearer-term idea of the currently positive AO, which will end in the next day or two) during the January 20-25 period. The 500 mb pattern suggested a transition of sorts in the AO region. This idea gave me further confidence that the second half of the thaw would see more sustained warm anomalies that the front half. The guidance is hinting at such a possibility.

Back then, I noted:

Given some of the 500 mb forecasts on the ensembles, I could see the AO going positive for a time in the January 20-25 timeframe, even as the majority of ensemble members keep the AO negative. Such an outcome would increase prospects for above to possibly much above normal readings during the closing days of the thaw. During the January 20-30, 1981-2010 base period, the mean temperature for a PNA of -0.75 or below/AO+ is 39.6° vs. 31.9° for climatology.

https://www.americanwx.com/bb/topic/50695-january-2018-discussions-observations-thread/?do=findComment&comment=4768918

Overnight, the GEFS has turned strongly to that idea (see attached image). In my view, this is not a bad development. Instead, it is the kind of transition that has often preceded a return to sustained blocking.

It's the development of such blocking that will prove important in influencing the long-term February outcome. Right now, I remain confident in the return of the EPO-/AO-/PNA+ pattern that has defined winter 2017-18 so far.

Before then, I suspect it will be at least a week before there are any snowfall opportunities for the NYC area (probably at least through 1/25). It remains possible that there could be an event that brings at least some measurable snow before the end of January, but that would be a bonus in what has been a snowy month.If things work out the way I am thinking right now, the first week of February will likely mark a transition. Then, there will be a 3 to perhaps 4-week period of frequently colder than normal weather (not unbroken) with above climatological probabilities of measurable snowfall. Considering that numerous La Niña-PDO winters have featured a 12" or greater snowstorm in NYC (and nearby regions), there could be a possibility of a large snowstorm at some point in February.

 

Your data and the outcomes thus far have matched almost perfectly, and I don't see why that won't continue. 

I am curious though that if 10/11 was one of the analogs for this season, then why did that winter end so abruptly while this one is likely to continue post thaw.  

[CIK62]

Next 8 days' average up to near 40degs., or +8degs. AN.

Month to date still -5.9degs.  Should be about -1.8degs. by the 27th.   Remainder of month [last 5 days] needs to be +9degs. to end at NORMAL.

GFS [06Z]  has no below normal days on the entire 16 day run.

[donsutherland1]

6 hours ago, SnoSki14 said:

Your data and the outcomes thus far have matched almost perfectly, and I don't see why that won't continue. 

I am curious though that if 10/11 was one of the analogs for this season, then why did that winter end so abruptly while this one is likely to continue post thaw.  

2010-11 wasn't a close match, though there had been a possibility of 2010-11-type snowfall in a highest-case scenario. 2000-01 was the closest match.

[donsutherland1]

Yesterday was the 12th day this month that the temperature fell below 20° at Central Park. The last time any month had at least as many such days was February 2015 when the temperature fell below 20° on 18 days. The last January with at least 12 such days was January 2015 when there were 13. The 12 such days this month is more than the total for winters 2015-16 (9) and 2016-17 (10).

New York City’s Average Temperature Through:

1/18: 26.5° (5.9° below normal)
1/20: 27.5°-27.8° (1/18 estimate: 27.4°-28.0°)
1/25: 29.7°-31.1° (1/18 estimate: 29.2°-30.8°)
1/31: 31.1°-33.5° (1/18 estimate: 30.4°-32.9°)

Per aggressive sensitivity analysis, the estimated probability of a below normal monthly anomaly: 52% (1/18 estimate: 57%)

At this point, the worst of January’s cold is now behind us. Through at least the medium-term, no additional sub-20° minimum temperatures appear likely for New York City. With some of the guidance, the overall probability of a colder than normal January fell sharply overnight. 

However, winter will likely only be “resting.” It very likely is not finished. Additional cold and quite a bit of snow likely still lie ahead.

[bluewave]

EPS weeklies still on track to a transition back to a more wintery pattern sometime during the 2nd week of February. But we have to get through the milder MJO phases first. 

 

 

 

[uncle W]

The  qbo is similar to 2000-01...1962-63...1967-68 and 1995-96 to a lesser extent...

[SnowGoose69]

7 minutes ago, bluewave said:

It will be interesting to see if we can transition back to El Nino conditions during 2018. We probably need to see what transpires in the Pacific this spring to know.

 

 

 

 I think it’ll end up neutral next winter.  You probably need to see the ENSO models showing at least a 1-1.5 right now for the 6-9 month period for a developing El Niño to be legit.  Usually when you’re in a non warm PDO the 9 month forecast averages about 0.7 below what the projections showed 

[bluewave]

2 hours ago, SnowGoose69 said:

 I think it’ll end up neutral next winter.  You probably need to see the ENSO models showing at least a 1-1.5 right now for the 6-9 month period for a developing El Niño to be legit.  Usually when you’re in a non warm PDO the 9 month forecast averages about 0.7 below what the projections showed 

I don't really have any opinion on next winter yet. But the warm waters at depth combined with the MJO may mean this current La Nina winds down early in February or March.

[frd]

1 hour ago, bluewave said:

I don't really have any opinion on next winter yet. But the warm waters at depth combined with the MJO may mean this current La Nina winds down early in February or March.

@bluewave if the current La Nina were to lessen in early Feb.,  is there a lag time that it would have an impact on our weather ?  Or, is it a non factor?  

[bluewave]

58 minutes ago, frd said:

@bluewave if the current La Nina were to lessen in early Feb.,  is there a lag time that it would have an impact on our weather ?  Or, is it a non factor?  

Good question. It may come down to the interaction between the MJO, PMM forcing west of the DL, and the La Nina strength and location.

[snowman19]

3 hours ago, SnowGoose69 said:

 I think it’ll end up neutral next winter.  You probably need to see the ENSO models showing at least a 1-1.5 right now for the 6-9 month period for a developing El Niño to be legit.  Usually when you’re in a non warm PDO the 9 month forecast averages about 0.7 below what the projections showed 

I agree 100% here. Next winter is very likely La Nada/neutral. Whether it’s cool-neutral or warm-neutral is anyone’s guess, but I think an El Niño is extremely unlikely 

[frd]

7 minutes ago, snowman19 said:

I agree 100% here. Next winter is very likely La Nada/neutral. Whether it’s cool-neutral or warm-neutral is anyone’s guess, but I think an El Niño is extremely unlikely 

Hmm, wonder if the next El Nino comes at the depth of the solar minimum,  or a year after the lowest peak. Something similiar to 09/10 maybe .

[frd]

26 minutes ago, bluewave said:

Good question. It may come down to the interaction between the MJO, PMM forcing west of the DL, and the La Nina strength and location.

Thank you. Will be interesting to see what happens. Maybe if there is a connection and the La Nina weakens we extend cold and snow chances deep into March .

[Paragon]

On 1/18/2018 at 8:51 PM, Isotherm said:

Weeklies remain steadfast with the idea that the second week of February is the inflection point, congruous with my thoughts. It's a warm to occasionally torch pattern prior to then. My primary question at this point is whether there will be NAO participation in the more auspicious pattern; that will likely be a function of the stratospheric evolution, still a bit indeterminate right now. Will know more in about a week. The vortex will receive some hard hits in early Feb via wave 2 amplification. At the very least, a weakening SPV is expected. Sometime in the second week of February through early March should yield a sustained wintry pattern.

That could be the snowiest pattern of the season, although not as cold as the early January pattern.  I expect our biggest snowstorm of the season will happen in the middle of February.

[Paragon]

18 hours ago, donsutherland1 said:

2010-11 wasn't a close match, though there had been a possibility of 2010-11-type snowfall in a highest-case scenario. 2000-01 was the closest match.

1995-96 may end up being a good match too if the Feb-Mar period delivers

[Paragon]

On 1/18/2018 at 11:42 AM, bluewave said:

The 90 inch seasonal snowfall record for LI has been the only snow record left that the 2010's haven't been able to break.95-96 had incredible Nov-Apr snow production.

https://www.bnl.gov/weather/4cast/MonthlySnowfall.htm

09-10 would have broken that record if we were at Toms River's latitude lol.

[Paragon]

On 1/18/2018 at 10:22 AM, donsutherland1 said:

The idea that the second half of the January thaw, which has seen some interruptions, would feature the longest period of sustained warmer than normal anomalies still appears on course. Around a week ago, I had some concern based on 500 mb pattern recognition that the AO could turn positive (this was a separate development from the nearer-term idea of the currently positive AO, which will end in the next day or two) during the January 20-25 period. The 500 mb pattern suggested a transition of sorts in the AO region. This idea gave me further confidence that the second half of the thaw would see more sustained warm anomalies that the front half. The guidance is hinting at such a possibility.

Back then, I noted:

Given some of the 500 mb forecasts on the ensembles, I could see the AO going positive for a time in the January 20-25 timeframe, even as the majority of ensemble members keep the AO negative. Such an outcome would increase prospects for above to possibly much above normal readings during the closing days of the thaw. During the January 20-30, 1981-2010 base period, the mean temperature for a PNA of -0.75 or below/AO+ is 39.6° vs. 31.9° for climatology.

https://www.americanwx.com/bb/topic/50695-january-2018-discussions-observations-thread/?do=findComment&comment=4768918

Overnight, the GEFS has turned strongly to that idea (see attached image). In my view, this is not a bad development. Instead, it is the kind of transition that has often preceded a return to sustained blocking.

It's the development of such blocking that will prove important in influencing the long-term February outcome. Right now, I remain confident in the return of the EPO-/AO-/PNA+ pattern that has defined winter 2017-18 so far.

Before then, I suspect it will be at least a week before there are any snowfall opportunities for the NYC area (probably at least through 1/25). It remains possible that there could be an event that brings at least some measurable snow before the end of January, but that would be a bonus in what has been a snowy month.If things work out the way I am thinking right now, the first week of February will likely mark a transition. Then, there will be a 3 to perhaps 4-week period of frequently colder than normal weather (not unbroken) with above climatological probabilities of measurable snowfall. Considering that numerous La Niña-PDO winters have featured a 12" or greater snowstorm in NYC (and nearby regions), there could be a possibility of a large snowstorm at some point in February.

 

Don, this is going to be a colder version of 05-06 I think.....put in 95-96, 00-01, and 05-06 into your analog list..... Feb-Mar-Apr 06 were cold/snowy, could have been even better though as we didn't take full advantage of the pattern. Biggest snowstorm of the season should be in the middle of Feb

[Paragon]

On 1/18/2018 at 11:54 AM, uncle W said:

I like the fact that it is thawing between the 19th-22nd...it fits the folklore...when winter returns it should be as good or bad as before the thaw...I'm on the Feb=Mar train as of now too...NYC has 18" of snow so far...I would not be surprised to see 15-20" more after the thaw...this is thaw two...I think we freeze and thaw a few more times before winters last blast...

Question is how long does this change to colder last for?  Second week of February to about the Third week of March?  So, like Feb 7 to about March 21?  About six weeks.

[CIK62]

Next 8 days up to an average of 40degs., or 8degs. AN.

Month to date is -5.6degs. and should be -1.6degs. by the 28th.   So last 4 days of the month will need to be about +10degs. to get to NORMAL.  If it is only +3degs. those days, we'll end with a -1deg. for Jan.

[bluewave]

Today looks like one of those days when the highs can beat guidance. WSW flow and +10c 850's.

[donsutherland1]

The New York City area is now in the midst of a more sustained period of warmer than normal readings. As the milder weather rolls on, it might be tempting for some to forget that January has been a snowy month in the greater New York City area.

Some snowfall statistics through January 19:

Bridgeport: January: 9.3”; Season-to-date: 18.0”
Islip: January: 16.0”; Season-to-date: 22.0”
New York City: January: 10.2”; Season-to-date: 17.9”
Newark: January: 9.4”; Season-to-date: 17.1”

New York City’s Average Temperature Through:

1/19: 26.8° (5.6° below normal)
1/20: 27.6°-27.9° (1/19 estimate: 27.5°-27.8°)
1/25: 30.0°-31.2° (1/19 estimate: 29.7°-31.1°)
1/31: 31.5°-33.7° (1/19 estimate: 31.1°-33.5°)

Per aggressive sensitivity analysis, the estimated probability of a below normal monthly anomaly: 50% (1/19 estimate: 52%)

The second and more sustained part of the January thaw is now unfolding. Initially, with the AO having gone negative again, there might be some fleeting and modest shots of cooler air. However, remaining 12 days of January will likely feature a warmer than normal anomaly for the period as a whole. However, this is a thaw, not the unofficial end of winter. In the longer-range, there are growing indications that the familiar EPO-/AO-/PNA+ pattern will take hold in February.

In terms of a timeline, this is how I currently see things:

January 20-31: Generally warmer than normal with perhaps a short-duration shot of cooler air (somewhat below normal to near normal for a day or two). Lower than climatological probability of snowfall.

February 1-7: A transitional period. The AO should go negative, if it went positive preceding this period. The trough in the west begins to migrate eastward. Temperatures remain above normal for the period as a whole, but there might be another temporary shot of cooler air. Lower than climatological probability of snowfall, but the probability could begin to increase toward the end of the period.

February 7-10: The trough reaches eastern North America (possibly centered over southeastern Canada), probably near the end of the period. It then locks in for 3 to possibly 4 weeks. Support for this scenario is shown on the CFSv2 and EPS weekly guidance.

[snowman19]

6 minutes ago, bluewave said:

Today looks like one of those days where the highs can beat guidance. WSW flow and +10c 850's.

I’m already up to 36 degrees and sunny in Sloatsburg. Don’t see any reason why we can’t at least hit 50 easily here this afternoon 

[CPcantmeasuresnow]

I looked at 13 different sites in the Northeast this morning pretty much in a circle from Hartford to Albany to Binghamton down to Allentown and Atlantic City and everything in between. Below is what we have so far through January 19.

Central Park 5.6° below normal LaGuardia -6.8° JFK -7.0°, I slip -4.8° Bridgeport -6.0° Newark -5.5° Poughkeepsie -6.0° Albany -4.2° Allentown -4.4° Atlantic City -5.9° Binghamton -5.9° Scranton -5.8° and Hartford -4.4°.

Pretty much if you average them out we would be about 6° below normal Fahrenheit regionwide. With 12 days left in the month we would have to be about 10° above normal for the last 12 days to end up above normal for the month. Let's hope that doesn't happen.

 

[NEG NAO]

16 minutes ago, CPcantmeasuresnow said:

I looked at 13 different sites in the Northeast this morning pretty much in a circle from Hartford to Albany to Binghamton down to Allentown and Atlantic City and everything in between. Below is what we have so far through January 19.

Central Park 5.6° below normal LaGuardia -6.8° JFK -7.0°, I slip -4.8° Bridgeport -6.0° Newark -5.5° Poughkeepsie -6.0° Albany -4.2° Allentown -4.4° Atlantic City -5.9° Binghamton -5.9° Scranton -5.8° and Hartford -4.4°.

Pretty much if you average them out we would be about 6° below normal Fahrenheit regionwide. With 12 days left in the month we would have to be about 10° above normal for the last 12 days to end up above normal for the month. Let's hope that doesn't happen.

 

the next 7 days should average out about 7 1/2  degrees above normal according to uptons highs and lows forecast that leaves us with 5 days at the end of the month still to be determined and too far out to accurately predict BUT we should still end up at least 1- 2 degrees below normal for the month with above average snowfall in many areas of the metro so the month will go down as cold and snowy . In February - it might be more difficult to erase the first 7 days of above normal since it is a short 28 day month BUT chances are Feb will end up just like Dec and Jan - cold and snowy.

[bluewave]

3 minutes ago, NEG NAO said:

the next 7 days should average out about 7 1/2  degrees above normal according to uptons highs and lows forecast that leaves us with 5 days at the end of the month still to be determined and too far out to accurately predict BUT we should still end up at least 1- 2 degrees below normal for the month with above average snowfall in many areas of the metro so the month will go down as cold and snowy . In February - it might be more difficult to erase the first 7 days of above normal since it is a short 28 day month BUT chances are Feb will end up just like Dec and Jan - cold and snowy.

The pre-Christmas thaw along with the warmth last weekend and the rest of the month prevented us from getting 2 consecutive -5 or lower departure months..

[Snowshack]

17 minutes ago, NEG NAO said:

the next 7 days should average out about 7 1/2  degrees above normal according to uptons highs and lows forecast that leaves us with 5 days at the end of the month still to be determined and too far out to accurately predict BUT we should still end up at least 1- 2 degrees below normal for the month with above average snowfall in many areas of the metro so the month will go down as cold and snowy . In February - it might be more difficult to erase the first 7 days of above normal since it is a short 28 day month BUT chances are Feb will end up just like Dec and Jan - cold and snowy.

Thats why i don't think monthly departures and snowfall are all that matters.   This month could very well wind up with more days of positive departures at my station than negative, despite averaging out slightly below.   We'll also probably finish with 8 days of 1" or more snowcover.   Does that make it cold and snowy?   Technically I suppose.  But nor particularly.    

[BxEngine]

1 hour ago, bluewave said:

Today looks like one of those days when the highs can beat guidance. WSW flow and +10c 850's.

Yeah we underperformed by about 8 degrees here yesterday but we're already 20 degrees off the low at 10 am this morning.