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Winter 2020-21 Medium/Long Range Discussion


Hoosier
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45 minutes ago, mimillman said:

GFS says next weekend ain't over

Thermals could be a problem in the end but it's definitely not over for us.  

Going forward, I think we can generally say that the pattern is more questionable if not hostile the farther southeast you are.  Though some areas did cash in with a pretty good amount of snow in December, like parts of Ohio.

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Is the +EPO the poor Pacific pattern?

In general, yes, it also matters the position of the troughing in the EPO domain (northeast Pac) as to how hostile a pattern it is. When there's a strong PV lobe parked over much of Alaska, it's pretty much game set match, which is what happened in 2011-12. Moving forward, it's important to keep some Aleutian ridging to allow for cold air to get closer to our source region. The background pattern on the end of the last few ensemble runs is definitely a milder look with a +EPO, but possibly not a death knell if the troughing sets up far enough east/southeast in the EPO domain, particularly if the -AO/-NAO continue. 

 

 

Took a look at the MJO phase plot forecasts, with GEFS and to a greater extent the ECMWF, wanting to pop it into phase 6, a warmer phase for Feb, which probably helps explain the +EPO tendency late in the ensemble runs. I'm certainly not a MJO expert, but from what I do know, the lower the amplitude of the MJO wave, the weaker the influence on the pattern, which makes sense.

 

Even the guidance that pops it into phase 6 are showing a pretty low amplitude, while the bias corrected GEFS keeps it basically in the COD, and the CFS suggests p7, a mild but not as warm phase for Feb (p7 composite looks fairly similar to mod-strong La Nina base state). Since it took quite a while to get to a -EPO and was delayed a bit from earlier forecasts, perhaps there's reason to think a quick reversion to +EPO might be rushed as well.

 

 

 

 

 

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This years Nov-Dec MEIv2 came in at -1.2C. Oct-Dec ONI came in at -1.3C. 

Below are February & March composites from the 6 years since 1979 with Nov-Dec MEIv2 between -1.0C & -1.5C. This gives a good idea of our current "base state" from ENSO... not accounting for any SSW impacts. Because the SSW has been impacting the polar height field (i.e via -AO/NAO) and will continue to do so, I don't think these are a perfect representation of what the overall pattern will look like. However... this 500mb look could certainly show up through the Feb-March period.

Jfnh7MaazG.png.f6a773d758eced7c3ea80e34f6d23152.pnglfYEKGyD_k.png.bbb11c3f80070293fccb6145b7200518.png

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49 minutes ago, blizzardof96 said:

This years Nov-Dec MEIv2 came in at -1.2C. Oct-Dec ONI came in at -1.3C. 

Below are February & March composites from the 6 years since 1979 with Nov-Dec MEIv2 between -1.0C & -1.5C. This gives a good idea of our current "base state" from ENSO... not accounting for any SSW impacts. Because the SSW has been impacting the polar height field (i.e via -AO/NAO) and will continue to do so, I don't think these are a perfect representation of what the overall pattern will look like. However... this 500mb look could certainly show up through the Feb-March period.

Jfnh7MaazG.png.f6a773d758eced7c3ea80e34f6d23152.pnglfYEKGyD_k.png.bbb11c3f80070293fccb6145b7200518.png

Wouldnt mind a warm spring for a change so hoping that happens. Could be a very early spring vegetation wise in the SE and up into the Great Lakes. 

Im also thinking that the Lakes have little chance of getting a good solid ice cover this year which should help out locally with early spring temperatures. 

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The 12z Euro solution really underscores how much time there is until we'll have a better grasp on the eventual outcome. Slower ejection of the main wave from the southwest allowed for more suppression by the northern stream and blocking. The million dollar question is can we find the sweet spot between the blocking exerting an influence but not too much and the southern stream wave timing.

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18 minutes ago, RCNYILWX said:

The 12z Euro solution really underscores how much time there is until we'll have a better grasp on the eventual outcome. Slower ejection of the main wave from the southwest allowed for more suppression by the northern stream and blocking. The million dollar question is can we find the sweet spot between the blocking exerting an influence but not too much and the southern stream wave timing.

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Yep they ain’t got a clue 

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1 hour ago, mississaugasnow said:

Wouldnt mind a warm spring for a change so hoping that happens. Could be a very early spring vegetation wise in the SE and up into the Great Lakes. 

Im also thinking that the Lakes have little chance of getting a good solid ice cover this year which should help out locally with early spring temperatures. 

Honestly I cannot remember the last time we had what I would consider an average Spring green up here. Most of the time it has run late than of course we had the ridiculous early in 2012. 

 

 I do want to caution that regardless of what kind of Winter it is the weather in March and April is the main factor for Spring green up.  Some of the region's most notoriously warm winters of years past had widespread reports of flowers blooming mid Winter, even some trees blossoming (1889-90, 1918-19, 1931-32), but March ans April cold snaps were all that was needed to halt any early Spring green up. Likewise, before 2012, by far the earliest spring Greenups we had seen were 1945 and again in 1946, due to big March torches. What was crazy about 1945 is that it came after a pretty severe winter (which in itself was rare for the meager winters of the 40s). So really what happens in spring is the main factor.

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The problem is the amplification downstream on the west coast tends to scour out s/w's. As the models get closer to 120 hours they slow down and that slows the ejection out of the southwest of the mean trough. Anything in the 168-240 hours period is more worthless than usual this year.

more or less worthless than your posts?


.
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Even though it's low skill range the euro weeklies for February seem to have a little less nino and a little more Nina look with warm to the South and cold to the North. Our sub for the most part looks pretty average temp wise with some periods of active weather. 
The 12z EPS already was already a slight improvement from the 00z run out in the extended, with Aleutian ridging farther east and more poleward.

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Just now, RCNYILWX said:

The 12z EPS already was already a slight improvement from the 00z run out in the extended, with Aleutian ridging farther east and more poleward.

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Theres always room for pessimism but I will leave that to the usual pessimists. A few things to remember especially as we've been stuck in this stagnant pattern for so long. We do not need a map to be full of blues to get snow in midwinter. It's about that time for the annual sun angle comments to laughingly start but like it or not, February has been a better snow month for this region than December for a while now. The euro weeklies looked decent to me. A few things that interest me... the signal for above average precipitation in February. This is seen not only on the euro weeklies but especially on the cfs. The cfs temperature scheme changes rapidly run to run but its wet look is pretty consistent.  Another thing to note is when you look at certain runs of the cfs or euro weeklies, including their control runs, some of them show very impressive cold later into February, whether it stays North of the border or dives down into the heart of the US. Before everyone carries on with the it's always 10 days away mantra, if you recall for the longest time Canada was an inferno on those maps run after run so at the very least a source of real cold seems to be getting closer. I mean the models have been terrible in every sense of the word but still, if we're going to look at them, it's not a bad look.

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