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January Forecast Discussion


REDMK6GLI

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Poor Run-to-Run Continuity Can Undermine Forecasts (even the best ones)...

 

Back on December 26, I noted in Message #70 in response to another message in which the CPC forecast had been cited favoring a warmer than normal outcome along much of the East Coast for the January 3-9, 2015 period, that such an outcome was not a "slam dunk," as the guidance had been experiencing less than normal run-to-run continuity in the medium- and extended-range. I noted that the GFS ensembles were suggesting caution and even showing the arrival of "some Arctic air."

 

Indeed, the Arctic air arrived, resulting in NYC having its first consecutive winters with a minimum temperature below 10° in ten years.

 

A comparison of the CPC probabilistic idea and the temperature anomalies is below.

 

January3to92015_Temperature_Anomalies.jp

 

In sum, uncertainty should garner a measure of respect in discussions, especially during times when the guidance is showing inconsistent solutions. One should at least know that there is a lot of risk during such times and that things are not necessarily cast in proverbial stone.

That was an excellent caution call Don, once again great insight.
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Our January thaw begins on the the 15th as the Arctic air retreats north.

NEW YORK CITY-CENTRAL PARK KNYC   GFSX MOS GUIDANCE   1/12/2015  0000 UTC                        FHR  24| 36  48| 60  72| 84  96|108 120|132 144|156 168|180 192       MON  12| TUE 13| WED 14| THU 15| FRI 16| SAT 17| SUN 18| MON 19 CLIMO X/N  42| 25  28| 19  34| 26  36| 28  40| 30  41| 34  45| 35  45 24 38

It's a short warmup according to the Euro

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Our January thaw begins on the the 15th as the Arctic air retreats north.

NEW YORK CITY-CENTRAL PARK
 KNYC   GFSX MOS GUIDANCE   1/12/2015  0000 UTC                       
 FHR  24| 36  48| 60  72| 84  96|108 120|132 144|156 168|180 192      
 MON  12| TUE 13| WED 14| THU 15| FRI 16| SAT 17| SUN 18| MON 19 CLIMO
 X/N  42| 25  28| 19  34| 26  36| 28  40| 30  41| 34  45| 35  45 24 38

That will not be enough to bring us above avg for the month

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We never got that big cutter to Chicago to help split the PV. Instead we've had storms moving into the eastern lakes and then SE Canada which has only helped to strengthen the PV. As much as people hate cutters, they are absolutely necessary if you want to break up a bad pattern. Otherwise the best we can hope for is some type of over running event and to date they have been poorely timed.

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We never got that big cutter to Chicago to help split the PV. Instead we've had storms moving into the eastern lakes and then SE Canada which has only helped to strengthen the PV. As much as people hate cutters, they are absolutely necessary if you want to break up a bad pattern. Otherwise the best we can hope for is some type of over running event and to date they have been poorely timed.

The PV just went through a pretty good split. It was the main player from last weeks cold shot. its recovering as we speak. 

ecmwf30a12.gif

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The MJO remains at a very high amplitude (currently Phase 6). Since 1974, there were 12 January cases that saw the MJO reach an amplitude of +2 or higher while in Phase 5 and/or 6.

 

The February snowfall outcomes varied and the development of strong blocking (AO) was key. The following are the February snowfall totals for NYC following the high amplitude Phase 5 or 6 January cases.

 

AO fell to -2.5 or below in the January 20-February 10 timeframe:

1978 23.0"

1986 9.9"

2006 26.9"

2013 12.2"

 

AO did not fall to -2.5 or below in the January 20-February 10 timeframe;

1976 5.0"

1989 0.3"

1990 1.8"

1993 10.7"

1995 11.6"

2007 3.8"

2008 9.0"

2011 4.8"

 

The main point is not to worry so much about the current state of the MJO. It is to watch for the development of strong blocking. Without it, odds would be skewed toward below normal snowfall for February. On the other hand, with the development of such blocking, there would be an increased probability of above normal snowfall. That connection between the AO and February snowfall is based on the 1950-2014 dataset. The MJO cases merely reflect that larger set of data.

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Our January thaw begins on the the 15th as the Arctic air retreats north.

NEW YORK CITY-CENTRAL PARK KNYC   GFSX MOS GUIDANCE   1/12/2015  0000 UTC                        FHR  24| 36  48| 60  72| 84  96|108 120|132 144|156 168|180 192       MON  12| TUE 13| WED 14| THU 15| FRI 16| SAT 17| SUN 18| MON 19 CLIMO X/N  42| 25  28| 19  34| 26  36| 28  40| 30  41| 34  45| 35  45 24 38

 

 

The thaw doesn't look to be long-duration or impressive in magnitude, unless we get a cutter to surge us over 60 in that time frame. By and large appears to be 40s, maybe a day or two of 50s, which isn't that impressive. The -EPO is already reloading by the 20th-21st. The final temperature departures for January will probably be -2 to -3 or colder for NYC IMO.

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But the +AO will keep the SE RidgeWAR as just enough of a factor to limit our snowfall potential so the

temperature departures won't be the big story. You saw the SE Ridge pulse up ahead of todays

storm which turned out to be rain at the coast. There can still be below normal temps on average

with a SE Ridge/WAR nearby, but the gradient gets pushed too far north with an amplified storm that delivers

heavier precip amounts.

Agree. Great to see you stand ur ground. You have been correct on many points this winter. Even we that wholfsheep guy trolling u

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So I guess more of the same going forward...with limited snow chances with no neg AO ..plus the Pv is in a bad spot

 

I find it hard to believe the GFS ensembles are going to be this wrong on the AO, the average beyond Day 10 is now almost -1 on the ensembles with 0.5 being about the highest any one member shows...I think the AO is going to at least neutral, its just a question of whether its for more than 5 days.

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So I guess more of the same going forward...with limited snow chances with no neg AO ..plus the Pv is in a bad spot

Gona have to take your chances with the cold . What comes along with these 2m temps is any ones guess . These are the 2M temp

 

We get cold again Jan 24 as the trough is back in the east .

I already posted the next 10 days there is no blowtorch the warmth is transient .

post-7472-0-16310000-1421097521_thumb.pn

post-7472-0-87033200-1421097530_thumb.pn

post-7472-0-01880600-1421097540_thumb.pn

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Agree. Great to see you stand ur ground. You have been correct on many points this winter. Even we that wholfsheep guy trolling u

Cute. Trolling me across boards now.

 

Looking at today's 12z runs, we have some agreement on a -EPO/+PNA in the LR and the EPS wants to dump some very cold departures into the NE, pump the -EPO and continue with high latitude blocking over Greenland.

 

How things turn out is up in the air. YOU have seen many pros and hobbyists with way more knowledge than you, give explanations in great detail as to why things may yet turn around by the EOM. If it provides you more comfort to side with those calling for less snow and more se ridge influence, cool. That may in fact happen. And far be it for me to question anything Bluewave says, as you are right, he has been dead on all winter long.

 

The wildcard, I think, this time, is the MJO, which has not yet been favorable. The Euro now has this moving through phase 7 by EOM, and possibly continuing into the COD thereafter. It comes down to whether one believes the QBO or the MJO is the main factor in governing our weather so far this winter. If you think it is the QBO, you will likely be resistant to believing that backloaded winter forecasts. If you believe that the MJO is the main player, you have no choice to accept the possibility that we may have a backloaded winter.

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Gona have to take your chances with the cold . What comes along with these 2m temps is any ones guess . These are the 2M temp

 

We get cold again Jan 24 as the trough is back in the east .

I already posted the next 10 days there is no blowtorch the warmth is transient .

Still, a little bit of white to go with those shades of blue would be nice.

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Cute. Trolling me across boards now.

Looking at today's 12z runs, we have some agreement on a -EPO/+PNA in the LR and the EPS wants to dump some very cold departures into the NE, pump the -EPO and continue with high latitude blocking over Greenland.

How things turn out is up in the air. YOU have seen many pros and hobbyists with way more knowledge than you, give explanations in great detail as to why things may yet turn around by the EOM. If it provides you more comfort to side with those calling for less snow and more se ridge influence, cool. That may in fact happen. And far be it for me to question anything Bluewave says, as you are right, he has been dead on all winter long.

The wildcard, I think, this time, is the MJO, which has not yet been favorable. The Euro now has this moving through phase 7 by EOM, and possibly continuing into the COD thereafter. It comes down to whether one believes the QBO or the MJO is the main factor in governing our weather so far this winter. If you think it is the QBO, you will likely be resistant to believing that backloaded winter forecasts. If you believe that the MJO is the main player, you have no choice to accept the possibility that we may have a backloaded winter.

Can't say I disagree with any of this...but as u said I'm on bluewaves train and feel the the reload will be no diff then early january. Will it get cold yes and this month will finish below avg...but the same old song with dry cold and cutters/buzzsaw.

Hopefully I'm wrong

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But the +AO will keep the SE RidgeWAR as just enough of a factor to limit our snowfall potential so the 

temperature departures won't be the big story. You saw the SE Ridge pulse up ahead of todays

storm which turned out to be rain at the coast. There can still be below normal temps on average

with a SE Ridge/WAR nearby, but the gradient gets pushed too far north with an amplified storm that delivers

heavier precip amounts.

 

 

What will be the impetus for the maintenance of a +AO in your view? Do you believe it will persist through late month and February?

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For us to really torch in the winter (60F+) we need higher than normal heights generally centered south of the area. Over the next week, the most anomalous high heights will be across the nern tier and SE Canada, such that high pressure is present at the surface, acting to keep some low level chilly air around the Northeast. We'll likely have several days of 40s, maybe into the 50s one day, but I'm not seeing a major surge of warmth in the thawing period 1/17-1/23.

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Almost all rain today and Thursday looking like it will be OTS -- who could have seen this coming? (and I'm not talking about myself)....  :whistle:

who could of seen it coming...the only thing that saw it coming on its own was the GFS originally...

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