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powderfreak

Early Winter Banter, Observations & General Discussion 2017

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I usually do not like starting threads but wanted to start one for this near record cold shot... the first arctic air mass moving into New England seems to signal a seasonal switch.  With the current model guidance continuing to show a change from the +10 or greater departures that have been so prevalent this fall, it really feels like we've turned the corner.

With -20C 850mb air moving towards NNE, that isn't a fall air mass.  That's the real deal.  Originated at the North Pole and finding its way to a location near you.  Thanks to the fall banter thread for this graphic. 

Lets see some cold obs in this thread over the next couple days.

23434976_10103223644682080_6502600410834

 

Someone should fire up a new model thread, too.  This isn't fall anymore.  Time to turn the page.

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17 minutes ago, STILL N OF PIKE said:

Anomalous cold shot.

Nice squall for good old N greens later

Powderfreak is amped up

I like to find a way to be neutral or reserved in forecasting/thoughts but I haven't found too many examples of November cold gone wrong in the subsequent winter.  These types of things seem to correlate much better than they do in Sept/Oct.  

That late autumn warm-up was well advertised as +15 departures at times... just think if that was the unanimous forecast now.  Luckily it looks favorable going forward.  Well timed.

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42 minutes ago, STILL N OF PIKE said:

Wondering if any squall  makes  it into SNH near am commute 

This front is a beast

I think we're too far south away from the vorticity, but we'll have to see when we get up!

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That was one of the more intense fronts last night.

Wind, thunder/lightning, followed by a nice coating of snow.

Everything is white this morning.

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14F with a wind chill of -1F at the base of the ski resort.  This is a crazy change.  Like being picked up and dropped off in January.

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2 inches plus at the notch entrance and snowing nicely. 14F according to the car.

Sent from my VS995 using Tapatalk

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I was looking at it today with a job shadow, and this wasn't the best forecast cold shot considering how anomalous it is.

Looking back at the NAEFS archive, a strong signal for a good cold shot didn't start showing up until 06.00z. You had to get into 3 days lead time to really see a signal for something significant/extreme. That's rather poor event horizon considering records have already been broken for the day. 

It seems like the ensembles washed out the signal (timing differences probably), whereas the deterministic runs kept showing some pretty legit cold.

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9 minutes ago, OceanStWx said:

I was looking at it today with a job shadow, and this wasn't the best forecast cold shot considering how anomalous it is.

Looking back at the NAEFS archive, a strong signal for a good cold shot didn't start showing up until 06.00z. You had to get into 3 days lead time to really see a signal for something significant/extreme. That's rather poor event horizon considering records have already been broken for the day. 

It seems like the ensembles washed out the signal (timing differences probably), whereas the deterministic runs kept showing some pretty legit cold.

This was a true shallow airmass. I wonder if the signal was weaker at 850. 925 and under ftw. 

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10 minutes ago, CoastalWx said:

This was a true shallow airmass. I wonder if the signal was weaker at 850. 925 and under ftw. 

Probably depending on where you were?  Like those 850mb temps we were talking about with a huge upslope/downslope component to the temps.  Up here the signal was very strong at 850mb.

For days the models have been showing -17C to -20C at 850mb up here and that seems to be verifying nicely.  Hard to turn your head to numerous runs showing -20C was a possibility.  How often do we even see modeled -20c entering New England?

So far Mansfield has gotten down to -17C and the mountain is usually a good representation of the 875-850mb level.

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3 minutes ago, CoastalWx said:

This was a true shallow airmass. I wonder if the signal was weaker at 850. 925 and under ftw. 

That's the bad thing about the WR site, no 925 mb.

You can find the GEFS though, and it really was around 06.00z that it jumped. 05.00z it was a -1.5 SD anomaly, fairly run of the mill for the ensembles for a below normal air mass, but by 06.00z jumped to -2.5 SD. 

So I wonder if the ensembles just snapped into better timing.

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Ridiculous for the afternoon of November 10th.

Just took the dog for a walk and its no joke cold.  Ambient temps in the teens out there with a breeze.  A crunchy coating of snow.  Still a few flurries falling too from time to time.

Nov10.jpg.e15a696079436ffbd7bf1c5eab819dc0.jpg

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2 minutes ago, powderfreak said:

Probably depending on where you were?  Like those 850mb temps we were talking about with a huge upslope/downslope component to the temps.  Up here the signal was very strong at 850mb.

For days the models have been showing -17C to -20C at 850mb up here and that seems to be verifying nicely.  Hard to turn your head to numerous runs showing -20C was a possibility.

So far Mansfield has gotten down to -17C and the mountain is usually a good representation of the 875-850mb level.

I think part of the problem with the ensembles heading into it was timing. If a member had -5 at 18z and -20 at 00z, and another had -20 at 18z today and -5 at 00z, the mean is going to be -12.5 (I know, extreme example but you get the idea). Cold, but not extreme. 

Good reminder that individual ensembles are important too.

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16 minutes ago, powderfreak said:

Probably depending on where you were?  Like those 850mb temps we were talking about with a huge upslope/downslope component to the temps.  Up here the signal was very strong at 850mb.

For days the models have been showing -17C to -20C at 850mb up here and that seems to be verifying nicely.  Hard to turn your head to numerous runs showing -20C was a possibility.  How often do we even see modeled -20c entering New England?

So far Mansfield has gotten down to -17C and the mountain is usually a good representation of the 875-850mb level.

Yeah the cold is deeper up against the slopes of the greens and whites. But this example is rather extreme for whatever reason. Part of it may be the delivery. At least 925MB allows cold to ooze through valleys that can run more N to S over in NNE. If this were more of a westerly delivery, it would be a downslope dandy here. 

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12 minutes ago, OceanStWx said:

I think part of the problem with the ensembles heading into it was timing. If a member had -5 at 18z and -20 at 00z, and another had -20 at 18z today and -5 at 00z, the mean is going to be -12.5 (I know, extreme example but you get the idea). Cold, but not extreme. 

Good reminder that individual ensembles are important too.

Yeah perhaps timing. I will say the euro ensemble 2 meter were pretty cold for several days now. 

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17 minutes ago, powderfreak said:

Ridiculous for the afternoon of November 10th.

Just took the dog for a walk and its no joke cold.  Ambient temps in the teens out there with a breeze.  A crunchy coating of snow.  Still a few flurries falling too from time to time.

Nov10.jpg.e15a696079436ffbd7bf1c5eab819dc0.jpg

DIT says this is standard fare for mid-November, nothing to see here.

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2 minutes ago, CoastalWx said:

Yeah perhaps timing. I will say the euro ensemble 2 meter were pretty cold for several days now. 

Yeah, I would say the last 4 days have been a legit signal, but considering how long we've been talking about this cold shot I'm surprised the ensembles were pretty meh before that.

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