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December 2016 Discussion & Observations


bluewave

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Play it save.  The CFSv2 shows no pattern breakdown till mid Jan., if then.  Mid-Jan. output has off the scale warmth slated for us.  I like +6 during first half of month.  Hope I do not know what I talking about here.  This looks like a modified version of last winter.  Let's hope we get the same anomalous events.  

The memory of tomorrow's short lived snow, may need to last 3 weeks.

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OK then.  What are you guys using to predict below normal temps. anytime soon?   All the ensembles I have access to w/o paying, have no below normal 500mb heights here for at least 16 days.    It does not look like it is about to change at time either  ie., early Jan.   

We need punctuated change in the form of a SSWE in the right place.   Just like a 9.0 earthquake can quickly change an areas geography.

 

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1 hour ago, Eduardo said:

Would probably diminish chances of a torchy February and an early end to winter that people like earthlight forecasted, correct?

Tough to speculate on the pattern beyond the next few weeks. One thing is for sure, the AO has been in full December disappointment mode 

following the amazing run from 2000 to 2010.

 

ao.sprd2.gif

 

 

 

 

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6 minutes ago, CIK62 said:

OK then.  What are you guys using to predict below normal temps. anytime soon?   All the ensembles I have access to w/o paying, have no below normal 500mb heights here for at least 16 days.    It does not look like it is about to change at time either  ie., early Jan.   

We need punctuated change in the form of a SSWE in the right place.   Just like a 9.0 earthquake can quickly change an areas geography.

 

Who is predicting below normal temps after this cold spell? 

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4 minutes ago, bluewave said:

Pretty extreme AO volatility since 2000 with the 2 highest and 3 lowest monthly values on record.

 

tsgcos.corr.173.77.158.168.350.10.15.47.png

 

 

 

get ready for some 60's chin music...both are forecast to drop at the end of the period...it's like trying to hit when Bob Gibson is pitching but he's taken out and is replaced with Ed Whitson...I think December ends up above the 30 year normal because the ao will finish on the plus side for December...

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4 hours ago, uncle W said:

get ready for some 60's chin music...both are forecast to drop at the end of the period...it's like trying to hit when Bob Gibson is pitching but he's taken out and is replaced with Ed Whitson...I think December ends up above the 30 year normal because the ao will finish on the plus side for December...

At least we got a decent -EPO/-NAO pattern December 1-17th before we go +EPO/+AO to close out the month.

 

500.gif

 

eps_z500a_5d_nh_21.png

eps_z500a_5d_nh_41.png

 

 

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this December has six days with a minimum of 32 or lower...last year there was none in December...the total average for days 32 or lower in December has fallen rapidly...the 2010's are averaging 11 counting this year so far...

2010-16.....13

2000-09.....16.4

1990-99.....12.3

1980-89.....16.4

1970-79.....15.8

1960-69.....20.0

1950-59.....16.3

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40 minutes ago, uncle W said:

this December has six days with a minimum of 32 or lower...last year there was none in December...the total average for days 32 or lower in December has fallen rapidly...the 2010's are averaging 11 counting this year so far...

2010-16.....13

2000-09.....16.4

1990-99.....12.3

1980-89.....16.4

1970-79.....15.8

1960-69.....20.0

1950-59.....16.3

Mon-Weds should all get below freezing so that makes 9. We will probably end up around the new normal of 13.

If you take out last year, this decade won-t be that much below others. Averaging a 0 in really kills the mean..my mom and I are teachers so we know that.

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Stratospheric 10hpa temperatures should reach record lows at 90N in the next week, and near record lows at 60-90N around Christmas. The tropospheric regime is reflective of that w/ a +5 standard deviation AO next week. Accumulating snow (of the 3"+ variety) at the coast will be nothing short of a Christmas miracle over the next week to 10 days.

If this year's vortex follows a progression congruous with prior similar historical cases, it will remain potent through all of January, with a weakening trend at the end of the month, followed by potential SSW attempt and/or significant weakening in the first half of February. That would induce tropospheric alterations such that Feb 5/10-end of winter delivers the most NAO / AO domain blocking of the season. This is all "a priori" of course, and we could very well have a strong vortex through March. However, historically, similar cases will yield at least a weakening in February, and thus probably our highest probability of protracted -AO/NAO is Feb/Mar.

The VP is suggestive of a potentially very west based poleward ridge -- meaning dateline and westward, which would force some cold delivery into the N CONUS, but would be ineffective for our case in light of the mean NAM/NAO regime. Basically, what I'm saying is that I am skeptical that the poleward ridging - if it develops in a protracted fashion - will be sufficiently far east to induce a good pattern on the East Coast given the absence of Arc / Atl blocking. I could see chances like we had today, but as far as SECS+ potential, it would be tough.

I'm searching for that seemingly elusive NAO/AO shake-up, which is probably far off at this point. We should punch the clock and begin wave-2 driving once the precursor pattern initiates over the next week, so convergence probably maximizes circa Jan 15th. Then we'll have to see the extent to which other forcings constructively or destructively interfere as it pertains to the subsequent vortex state in Jan 15-30.

Fun pattern to forecast though for sure.

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17 minutes ago, weatherfreeeeak said:

Any more snow chances for the rest of December 

Today will probably be the biggest snowfall of the month as we go +EPO/+AO . The -EPO pattern provided the Arctic air necessary for the heavier snowfall.

But it's still possible that a lighter accumulation event than today can sneak in before the month is out.

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1 hour ago, bluewave said:

Today will probably be the biggest snowfall of the month as we go +EPO/+AO . The -EPO pattern provided the Arctic air necessary for the heavier snowfall.

But it's still possible that a lighter accumulation event than today can sneak in before the month is out.

I agree. Since 1950, there have been 12 4" or greater snowstorms in NYC during the last 10 days of December. Nine (75%) occurred with an AO-. When the ENSO Region 3.4 anomaly was < 0°C, all six such storms occurred when the AO was negative. 

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Since 1985 there has never been a December in Central Park with between 3.1-5.9 inches of  snow, despite the 30 year average being in the middle of that range at 4.8 inches.

Right now Central Park is at 3.2 so here's to hoping they don't break that 31 year streak and get to 6.0 or over by the end of  the month

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