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Hoosier

Winter 2019-20 Medium/Long Range Discussion

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4 minutes ago, IWXwx said:

GFS is trolling the East Coast with a 954mb bomb :popcorn:

 

gfs_mslp_pcpn_frzn_neus_40.png

Groundhog day, which means it has to be farther west.

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4 hours ago, Hoosier said:

Groundhog day, which means it has to be farther west.

On 1/5/2020 at 4:07 PM, Snowstorms said:

LOL. Feb 1-3 GHD part 3. Book it. 

 

 

 

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On the 14th I thought we were 10-15 days away from a more legitimate pattern change...clearly, things are not going as smoothly as I had hoped (though the upcoming pattern is not as bad as what we had for the last half of December and first half of January).  A combination of a very strong stratospheric polar vortex (that is coupled to the troposphere), increased AAM not being deposited favorably yet, and MJO not making it into phase 8 are hurting us.  I'll try to touch on all of these briefly and try to make an educated guess on whether or not they'll change.

One point I've had to stress to clients at work (especially here on the East Coast where our snow climo is more back-loaded than the Midwest) is that we still average roughly half of our snow from here on out (it's about or slightly less than half for most Midwest stations off the top of my head).  While the road begins getting narrow for deep winter cold and prolonged snow cover as we head into February, there's still time to snow. 

The issues we've faced this winter have gone back to a long-running issue since the fall...Indian Ocean forcing dominated the tropics for a good portion of fall and early winter, severely muting a weak/borderline central Pacific based El Nino for extended periods of time.  Indian Ocean forcing is not a cold signal on its own in the middle of winter, and with a lack of Pacific forcing (which is a cold signal, especially when it's over the central/eastern Pacific), the stratospheric PV intensified quickly.  The QBO not going negative until after the start of January provided a favorable background state for the PV to get strong, and there was minimal Pacific tropical forcing in December, which is peak intensification time for the strat PV and allowed it to get very strong.  This wasn't a death knell on its own, but when this strong PV coupled to the troposphere in early January it became much more problematic.  A strong stratospheric PV favors a +AO, NAO, and +EPO with troughing into the Pacific Northwest, which happens to be a common theme the last several weeks that does not go away despite what mid-range modeling says.  We've seen much more robust Pacific tropical forcing the last few weeks as the AAM has sharply increased, which is why the models and people such as myself have been hoping for a change, but the strong and coupled PV has continued to dominate.  The most recent MJO propagation and AAM surge are the most significant attempts yet to disrupt this pattern, and results while still uncertain, are not going to be as quick and effective as hoped, owing to the strength and persistence of the strat PV and its coupling to the troposphere. 

We'll start with the strong and coupled stratospheric PV:

AM.png.e4f463a8abd435f6b0d8c921ffa10809.png

This is basically the AO with height...there was a cool tropospheric-stratospheric-tropospheric event in late November/December when a blocky troposphere sent waves up into the stratosphere that weakened the stratospheric PV, which then in turn down-welled and produced a period of blocking in the troposphere in mid December.  Since then it's been off to the races, with the stratospheric PV getting strong by mid-late December and coupling by early January, with a very strong PV/positive AO throughout the troposphere and stratosphere.  Until we disrupt this, a prolonged cold pattern or high-latitude blocking is unlikely.

The good news is the stratospheric PV begins weakening climatologically fairly substantially in February, though is it quick enough to salvage much of anything?

Tackling the AAM and its initial lack of impact on the pattern (usually an increase in AAM makes the high latitudes blockier and disrupts the stratospheric PV):

AAM by latitude on January 16th:

847134424_AAM1-16.thumb.png.60bcb23d781a7bc65acae715be2c2c41.png

The initial issue was the added momentum was not getting dispersed into the high-latitudes due to a band of low momentum in the sub-tropics.  You want momentum to increase in the sub-tropics and mid-latitudes and get dispersed in the high-latitudes...that did not happen initially, with high momentum dominating the sub-polar latitudes, likely at least partially due to the coupled and strong PV and resulting in a strong +AO.

Here is the AAM as of this morning:

674857302_AAM1-23.thumb.png.9cad39cf557c48ea7672cc85ce28ba35.png

That's not as bad, but still, there's a sink in the mid-latitudes indicative of a retracted Pacific jet and a band of high momentum in the sub-polar latitudes.  The upcoming robust positive East Asian Mountain Torque should extend the Pacific jet and increase momentum in the sub-tropics and mid-latitudes more than what we've seen so far, and is actually still fairly on schedule compared to what the ensembles were hinting at back in mid-January.  The EAMT looks fairly positive for the foreseeable future, though with notable peaks in the near-term, and potentially again in the 10-15 day timeframe.  Both should increase momentum in the mid-latitudes, we will see if that momentum gets properly dispersed into the higher latitudes in the face of the strong and coupled PV or not.

704327253_EPS24.png.742b98c00c12118e4cb2bb655dba45c1.png

And this could be quite a strong +EAMT if that high descends in the extended range:

701064516_EPS264.png.8ab292e256b16557a083414aba3f45cd.png

Tropical forcing remains more favorable than it was, despite the failure of the MJO to make it into phase 8...both the EPS and CFS suggest some uplift continuing over the central Pacific in February as the Indian Ocean uplift slowly weakens...the brief and weak phase 5-6 MJO shown next week on the RMM plots is a fast-moving Kelvin Wave that should help amplify this lower-frequency central Pacific forcing in early February:

147016489_EPSchi.thumb.png.98cde53ac5d860b0ed2fe59bed103578.png

Also, as wavelengths shorten through February, Indian Ocean forcing becomes less detrimental.

So, long story short, the strength of the stratospheric PV is both causing the bad pattern we've been in and making it more resistant to change than normal.  However, climatology, more active Pacific tropical forcing, an increase in momentum in the mid-latitudes due to positive East Asian Mountain Torque events, and shortening wavelengths all suggest that the stratospheric PV should gradually weaken, and in fact the extended range GFS op and EPS, which have both done well with showing a strong PV through the winter, do show some signs of weakening by early February.

I am somewhat in the camp of "I'll believe it when I see it" myself in regards to any sort of change to a substantially colder pattern, but the EPS weeklies and CFS continually show a seasonable to somewhat cold pattern developing during the first week of February and generally continuing through the month (with some ebbs and flows), and if we can ever shake the strong PV and the pattern it has created, the other sub-seasonal forcings don't really argue for warmth...the question is, can we do it in time to salvage a good chunk of February?  I don't know the answer and have gotten burned by being too optimistic on that timing over the last few weeks.

I do think in the next two weeks that we'll see the PNA spike positive at times as the +EAMT extends the Pacific jet, though the AO, EPO, and NAO will be a different story until the stratospheric PV gets knocked back some.  The earliest that can start occurring is 10-15 days from now, though I suspect it's not until at least the second week of February that we see more material changes in those areas, and until that time it will be tough to lock in any sort of cold air.  However, any PNA spikes may give us enough polar influence to make all of this subtropical jet energy running around at least a bit interesting in the meantime.

 

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My goodness OHweather, you are seriously GLOV poster of the year 2020 with these continuously informative posts which will spark research on many of us weenies’ part to learn more :D  Thanks!

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Excellent analysis OHweather. Keeping hopes alive for a wintry Feb.

 

And as for snow climo, tomorrow is the climatological halfway point of the snow season at Detroit. Half of the snow should have fallen, with half to come, so we pretty much are right at the midpoint now. As has been said, weve done fine from a snowfall total perspective, but not from a sustained winter one.

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56 minutes ago, snowlover2 said:

There's no dam way i'm lucky enough for this to happen.

gfs_mslp_pcpn_frzn_ncus_33.png

the pattern is definitely looking active but the massive turd in the punch bowl is the continued lack of cold air.   Most storms are gonna be a mangled mess of slop on their wintry side.    The only way to get a good shot of snow is to have a deep low like the one depicted...but a deep low also implies a much further nw track.   

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2 minutes ago, buckeye said:

the pattern is definitely looking active but the massive turd in the punch bowl is the continued lack of cold air.   Most storms are gonna be a mangled mess of slop on their wintry side.    The only way to get a good shot of snow is to have a deep low like the one depicted...but a deep low also implies a much further nw track.   

Mar 08 blizzard redux. Let's get it. 

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33 minutes ago, buckeye said:

the pattern is definitely looking active but the massive turd in the punch bowl is the continued lack of cold air.   Most storms are gonna be a mangled mess of slop on their wintry side.    The only way to get a good shot of snow is to have a deep low like the one depicted...but a deep low also implies a much further nw track.   

That's the GHD III noreaster it was spitting out yesterday, just faster and more inland. Looking at this winter's pattern, congrats WI and Alek's DAB+

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3 minutes ago, IWXwx said:

That's the GHD III noreaster it was spitting out yesterday, just faster and more inland. Looking at this winter's pattern, congrats WI and Alek's DAB+

Weather Channel TV just said the low could be somewhere between Detroit and the final resting place of the Titanic.

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Long range models indicating an increased chance of a SSW during the month of February.  Defintely not set in stone but slightly concerning for people hoping for a warm early spring.

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19 minutes ago, IWXwx said:

That's the GHD III noreaster it was spitting out yesterday, just faster and more inland. Looking at this winter's pattern, congrats WI and Alek's DAB+

This one may at least have a chance to not be a strung out/pos tilt mess as we have seen so often.  Typhoon Tip over in the SNE forum makes good points when you can actually understand what he's typing, and one of the things we don't have in this setup is a massively strong southeast ridge which tends to shear/grind up emerging s/w when heights get too high (according to him).  

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29 minutes ago, Hoosier said:

This one may at least have a chance to not be a strung out/pos tilt mess as we have seen so often.  Typhoon Tip over in the SNE forum makes good points when you can actually understand what he's typing, and one of the things we don't have in this setup is a massively strong southeast ridge which tends to shear/grind up emerging s/w when heights get too high (according to him).  

?  I would think a strong southeast ridge would favor a strong cutter as the incoming trough would sharpen and deepen more ahead of it.   Wouldn't less of a SER cause the storm to be more progressive?

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7 minutes ago, buckeye said:

?  I would think a strong southeast ridge would favor a strong cutter as the incoming trough would sharpen and deepen more ahead of it.   Wouldn't less of a SER cause the storm to be more progressive?

A strong southeast ridge would favor a cutter of some kind, but cutters come in all kinds of strengths.  You can get a big neg tilt trough with a very deep surface low or a strung out positively tilted trough with a 1005 mb low.  The stronger the southeast ridge, the more height gradient which increases the flow aloft which tends to have a deleterious effect on getting amped up storms.  There are probably exceptions but the way he said it makes sense.  We have been dealing with a pig ridge down there numerous times this winter and have not seen very many strong/neg tilt systems... coincidence?  

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20 minutes ago, buckeye said:

?  I would think a strong southeast ridge would favor a strong cutter as the incoming trough would sharpen and deepen more ahead of it.   Wouldn't less of a SER cause the storm to be more progressive?

If the energy on the backside is pressing in too fast it can end up sheared out. Along with if there is too strong of a ridge being formed out west behind the system. 

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Just now, Hoosier said:

A strong southeast ridge would favor a cutter of some kind, but cutters come in all kinds of strengths.  You can get a big neg tilt trough with a very deep surface low or a strung out positively tilted trough with a 1005 mb low.  The stronger the southeast ridge, the more height gradient which increases the flow aloft which tends to have a deleterious effect on getting amped up storms.  There are probably exceptions but the way he said it makes sense.  We have been dealing with a pig ridge down there numerous times this winter and have not seen very many strong/neg tilt systems... coincidence?  

This 

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1 hour ago, Hoosier said:

This one may at least have a chance to not be a strung out/pos tilt mess as we have seen so often.  Typhoon Tip over in the SNE forum makes good points when you can actually understand what he's typing, and one of the things we don't have in this setup is a massively strong southeast ridge which tends to shear/grind up emerging s/w when heights get too high (according to him).  

:lol: He seems like a super intelligent dude, but I feel like the absent-minded scrolling of forum posts screeches to a halt when I come across one of his posts and I have to really, really concentrate on what hes trying to say.

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44 minutes ago, Hoosier said:

A strong southeast ridge would favor a cutter of some kind, but cutters come in all kinds of strengths.  You can get a big neg tilt trough with a very deep surface low or a strung out positively tilted trough with a 1005 mb low.  The stronger the southeast ridge, the more height gradient which increases the flow aloft which tends to have a deleterious effect on getting amped up storms.  There are probably exceptions but the way he said it makes sense.  We have been dealing with a pig ridge down there numerous times this winter and have not seen very many strong/neg tilt systems... coincidence?  

I see the term "pig" often. I know its not good, but what exactly is it lol?

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21 minutes ago, michsnowfreak said:

I see the term "pig" often. I know its not good, but what exactly is it lol?

I just use it as a name for a big ridge.  I know some people use it for other things like when there's a big low in the Gulf of Alaska.  

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1 hour ago, michsnowfreak said:

I see the term "pig" often. I know its not good, but what exactly is it lol?

tip's post are literary masturbation....he seems to get off  using 50 words, (each with 3 or more syllables),  to say it's going to be cold tomorrow.   

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