December pattern change continued

[Typhoon Tip]

We'll have to hope we can muster up something in our transient PNA ridges out west.

It's hard to see beyond the confines of persistence. Sometimes persistence is like circa Dec 26th, 2011 through about February 10th, 2011; other times, persistence is wicked, cruel to those that are weather-reliant for their mirth.

Me, I try (however unsuccessfully at times) to maintain a disconnect, but that's another discussion.

Late last night I was looking over the daily PNA and AO index numbers going back to 1950. Yes, I am a tedious nerd. It got me thinking. I was looking at the 2 week delta(teleconnector) behaviors that preceded some of the more interesting intervals of weather in history. Sometimes I think that for all the advanced degrees required by NCEP/NWS in order to join their respective teams of evaluators of climate and such, I wonder if they are so too obliged to the complexities of the field that they may fail to look at things with perhaps simpler expectation in mind.

In virtually every case, the PNA was not amazing positive. The PNA was in fact > -1 and < +1 and rising or falling within that narrow SD variance around 0.0. Preceding most of the cold precipitation events along 40N were, however, a significant drop in the Arctic Oscillation, with a lesser coherent but still present suggestion in the NAO. That makes sense as the two share domain space above 55N. What this tells me is that based on that 50 year period, the first step in the ennui elixir recipe is the establishment of stronger horizontal thermal gradient around middle latitudes. Intuitively, have a bit of a relaxed PNA makes a good bit of sense to me. The reason is because if there is a strong cold loading into middle latitude while the PNA gets substantively positive, the preferred strong ridge expression over western N/A coupled with deep height anomalies along the longitude of the Ohio and Tennessee Valleys creates "too much" gradient. When that happens, the flow speeds up everywhere and gets too fast in the ambient air to allow individual impulses to be meaningfully differentiable on the field.

The only reason why storms occur at all is restoring forces; those forces that are required to conserve mass in the mechanics of atmospheric motion. If a strong jet max rides over a region at 500mb, that produces lower pressure aloft. The air than must "respond/restore" that lower pressure by moving toward, while conserving implicit influences from the Coriolis parameter (why highs and lows turn). That restoration of mass from higher to lower mass cannot come from above the jet maxes location(s) in time, because the mass is lower above it; so the restoring force initiates motion from below. These flows of air are often referred to as "inflow jets".

For example, the individual impulses typically will carry a 75 to 100kt wind max in the mid levels of the troposphere. If the PNA is relaxed (> -1 or < +1) this usually offers weaker ambient gradient, so the balanced wind is substantially less than 75 or 100kts during those times. A 100kt wind max moving through will thus cause strong restoring. If the PNA is hugely positive and the preferred western ridge is situated, than the balanced wind is already 75 to 100kts. Comparing the individual impulses (short waves) moving through such a domain, said short wave then cannot induce restoring in the field; no restoring, no inflow jets, no storm.

That basic paradigm may be why a -AO/+PNA that is very strongly coupled actually has less dramatic event frequency (not including cold or warm temperature anomalies respectively). Opposingly, a drop in the AO loads cold into middle latitudes. If there is then lower latitude relaxed height field that then supplies a significantly differential impulse that runs along that exaggerated temperature gradient, storms that form have intense thermal differentials and exhaustion of atmospheric energy then happens within the confines of the storm (intense). I suppose it would be possible - if this were all true - to show this mathematically: suppose the integrated energy (total) of the atmosphere at a given time were considered a quasi-constant, the summation of all events must then = that constant. Then it becomes a matter of arithmetic. Take a domain, find the total energy (gradient in the geopential balance), then add up the S/W energies, and subtract. If that differential is negative, this robs from storm energy; if it is positive, then storms have a surplus and will be stronger.

Interesting. I'd say right now storms are slightly in a negative mode based on that hypothesis. In any even, if this AO is in fact fallen the 3 SD (and continues), that may change as cold continues to load into the mid-latitudes (assuming an even distribution), while a quasi-static PNA persists that would suggests going positive. It doesn't say where ...but perhaps loosely when.

[Mr Torchey]

Yea it's possible we get a break with a Miller B that delivers to the north of SwCt area, oops I mean delivers for some of us.

XXX winter, its been incredible Steve, that pattern change after Halloweenie was incredible.

Merry xmas.

[CoastalWx]

It's hard to see beyond the confines of persistence. Sometimes persistence is like circa Dec 26th, 2011 through about February 10th, 2011; other times, persistence is wicked, cruel to those that are weather-reliant for their mirth.

Me, I try (however unsuccessfully at times) to maintain a disconnect, but that's another discussion.

Late last night I was looking over the daily PNA and AO index numbers going back to 1950. Yes, I am a tedious nerd. It got me thinking. I was looking at the 2 week delta(teleconnector) behaviors that preceded some of the more interesting intervals of weather in history. Sometimes I think that for all the advanced degrees required by NCEP/NWS in order to join their respective teams of evaluators of climate and such, I wonder if they are so too obliged to the complexities of the field that they may fail to look at things with perhaps simpler expectation in mind.

In virtually every case, the PNA was not amazing positive. The PNA was in fact > -1 and < +1 and rising or falling within that narrow SD variance around 0.0. Preceding most of the cold precipitation events along 40N were, however, a significant drop in the Arctic Oscillation, with a lesser coherent but still present suggestion in the NAO. That makes sense as the two share domain space above 55N. What this tells me is that based on that 50 year period, the first step in the ennui elixir recipe is the establishment of stronger horizontal thermal gradient around middle latitudes. Intuitively, have a bit of a relaxed PNA makes a good bit of sense to me. The reason is because if there is a strong cold loading into middle latitude while the PNA gets substantively positive, the preferred strong ridge expression over western N/A coupled with deep height anomalies along the longitude of the Ohio and Tennessee Valleys creates "too much" gradient. When that happens, the flow speeds up everywhere and gets too fast in the ambient air to allow individual impulses to be meaningfully differentiable on the field.

The only reason why storms occur at all is restoring forces; those forces that are required to conserve mass in the mechanics of atmospheric motion. If a strong jet max rides over a region at 500mb, that produces lower pressure aloft. The air than must "respond/restore" that lower pressure by moving toward, while conserving implicit influences from the Coriolis parameter (why highs and lows turn). That restoration of mass from higher to lower mass cannot come from above the jet maxes location(s) in time, because the mass is lower above it; so the restoring force initiates motion from below. These flows of air are often referred to as "inflow jets".

For example, the individual impulses typically will carry a 75 to 100kt wind max in the mid levels of the troposphere. If the PNA is relaxed (> -1 or < +1) this usually offers weaker ambient gradient, so the balanced wind is substantially less than 75 or 100kts during those times. A 100kt wind max moving through will thus cause strong restoring. If the PNA is hugely positive and the preferred western ridge is situated, than the balanced wind is already 75 to 100kts. Comparing the individual impulses (short waves) moving through such a domain, said short wave then cannot induce restoring in the field; no restoring, no inflow jets, no storm.

That basic paradigm may be why a -AO/+PNA that is very strongly coupled actually has less dramatic event frequency (not including cold or warm temperature anomalies respectively). Opposingly, a drop in the AO loads cold into middle latitudes. If there is then lower latitude relaxed height field that then supplies a significantly differential impulse that runs along that exaggerated temperature gradient, storms that form have intense thermal differentials and exhaustion of atmospheric energy then happens within the confines of the storm (intense). I suppose it would be possible - if this were all true - to show this mathematically: suppose the integrated energy (total) of the atmosphere at a given time were considered a quasi-constant, the summation of all events must then = that constant. Then it becomes a matter of arithmetic. Take a domain, find the total energy (gradient in the geopential balance), then add up the S/W energies, and subtract. If that differential is negative, this robs from storm energy; if it is positive, then storms have a surplus and will be stronger.

Interesting. I'd say right now storms are slightly in a negative mode based on that hypothesis. In any even, if this AO is in fact fallen the 3 SD (and continues), that may change as cold continues to load into the mid-latitudes (assuming an even distribution), while a quasi-static PNA persists that would suggests going positive. It doesn't say where ...but perhaps loosely when.

I think you are right in that some of the bigger storms didn't have a ridiculous +PNA. There is a such thing as too much of a good thing, as we learned with the -NAO in '09/'10. The ridge is important as it helps amplify the disturbance, but we don't need a large massive ridge from Mexico to the nw territories.

[OSUmetstud]

I think you are right in that some of the bigger storms didn't have a ridiculous +PNA. There is a such thing as too much of a good thing, as we learned with the -NAO in '09/'10. The ridge is important as it helps amplify the disturbance, but we don't need a large massive ridge from Mexico to the nw territories.

I remember talking about the 09-10 -NAO with will...it wasn't just that it was so strong...there was definitely some minor shortwaves that were very ill timed...and caused the confluence to increase to a ridiculous level. If you had a 09-10 like pattern again...I bet the chances are good that SNE would get more snow than they did that year.

[40/70 Benchmark]

I'm still hoping we can have a decent back half of winter, but La Nina's tend to go against that thinking.

Well, the late nineties clunkers that everyone likes to compare this season to got better as the season wore on.

IMBY

'98-'99- Dec 1", Jan 17.5", Feb 6.2", March 17.2"

'99-'00- Dec T, Jan 16.8", Feb 10.7", March 3.6", April 2"

[CoastalWx]

Euro FTW??

[CoastalWx]

I remember talking about the 09-10 -NAO with will...it wasn't just that it was so strong...there was definitely some minor shortwaves that were very ill timed...and caused the confluence to increase to a ridiculous level. If you had a 09-10 like pattern again...I bet the chances are good that SNE would get more snow than they did that year.

Yeah exactly. We had some real bad luck..it wasn't a true clunker pattern that we know and loathe.

[40/70 Benchmark]

I remember talking about the 09-10 -NAO with will...it wasn't just that it was so strong...there was definitely some minor shortwaves that were very ill timed...and caused the confluence to increase to a ridiculous level. If you had a 09-10 like pattern again...I bet the chances are good that SNE would get more snow than they did that year.

Agreed.....but the extreme strengh of the NAO increased the likelihood of that taking place up here....it was optimal for the MA.

[CoastalWx]

Well, the late nineties clunkers that everyone likes to compare this season to got better as the season wore on.

IMBY

'98-'99- Dec 1", Jan 17.5", Feb 6.2", March 17.2"

'99-'00- Dec T, Jan 16.8", Feb 10.7", March 3.6", April 2"

That's what I'm hoping and have a feeling will happen. It obviously has to get better because it can't get any worse..but I think it may get a little more favorable later in Jan and hopefully through March.

[CoastalWx]

Hopefully the euro op is onto something.

[dryslot]

Hopefully the euro op is onto something.

Yeah, Crack

[OSUmetstud]

Hopefully the euro op is onto something.

pretty funny upper level set-up to yield a low like that...but there's some hope I guess. Some parts of the Cape have the amount this season as Buffalo right now lol.

[Organizing Low]

snowing at the buffalo game today

[CoastalWx]

pretty funny upper level set-up to yield a low like that...but there's some hope I guess. Some parts of the Cape have the amount this season as Buffalo right now lol.

It is. Positively tilted trough..almost an overrunning type set up. The ensembles kind of hint at it too. S/W dampens out pretty considerably.

[OSUmetstud]

snowing at the buffalo game today

Yeah...we've got a coating...bfd lol. I can't see the Bills game anyway..not sold out.

[40/70 Benchmark]

That's what I'm hoping and have a feeling will happen. It obviously has to get better because it can't get any worse..but I think it may get a little more favorable later in Jan and hopefully through March.

Yea, and I hope and feel that the sun will rise again, after setting tonight.

I'm getting at least 20" more of snow this season and since I'll see nothing, or next to it, during the month of December, so it IS going to get better.

Not a large leap of faith, scooter.....put the caution flag in your pocket lol

[CoastalWx]

Yea, and I hope and feel that the sun will rise again, after setting tonight.

I'm getting at least 20" more of snow this season and since I'll see nothing, or next to it, during the month of December, so it IS going to get better.

Not a large leap of faith, scooter.....put the caution flag in your pocket lol

You know what I mean. I'm saying I don't think it will be a 15" winter BOS...a type of winter where it perpetually sux. But who knows.

[CoastalWx]

What a mess at 500 on the euro. Verbatim it keeps Messenger and Phil under hours of light snow or rain showers after brushing us with snow.

[40/70 Benchmark]

Give it the F up Steve. We are done. Accept it and get on with life

There really is a first for everything.

[CoastalWx]

Well you can see why the ridge out west COULD work in our favor, by sending disturbances south and having them try to amplify a bit. However, it's a really positively tilted trough which means things may not amplify too much. Perhaps a better chance near the 26th.

[Damage In Tolland]

Just in time for a X-mas miracle..It's coming

[CoastalWx]

Just in time for a X-mas miracle..It's coming

You are a freaking riot.

[40/70 Benchmark]

You know what I mean. I'm saying I don't think it will be a 15" winter BOS...a type of winter where it perpetually sux. But who knows.

I agree....my worst is a hair under 20" and I still expect ~45-55"

[40/70 Benchmark]

You are a freaking riot.

He's lost it....switches personalities every 5 minutes.

[Damage In Tolland]

You are a freaking riot.

It's all I;ve got

[Logan11]

Back from the dark side...

Just in time for a X-mas miracle..It's coming

[CoastalWx]

Could be classic euro digging energy too far south as it tries to cut off the storm way down in the GOM, but it's at least something and has been hinted by some ensembles. Might as well keep your fingers crossed.

[40/70 Benchmark]

Back from the dark side...

.....

[40/70 Benchmark]

Could be classic euro digging energy too far south as it tries to cut off the storm way down in the GOM, but it's at least something and has been hinted by some ensembles. Might as well keep your fingers crossed.

Or remain entirely uninvested and if by some chance it happens to snow, it snows....

[CoastalWx]

The euro op is kind of wintry in a way. Even though it keeps most precip over the Cape after the first low, onshore flow would probably cause a little light QPF from time to time with any disturbance for another 24 hrs afterwards...if you believe the op run. 5+ days out, so we know the caveats, but something may come about in those 3-4 days surrounding Christmas.