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Thanksgiving week transient cold shot and the pattern beyond


ORH_wxman

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We've had a very weak wave over the last two weeks which isn't doing squat for the pattern. Having this wave become stronger and move around the horn at least tries to shuffle the pattern around, especially after it moves out of the p3-5 area. I certainly don't want to see it fall into the circle of death, meaning the area corresponding to a very weak amplitude.

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Phase 5 is still warm for us but it starts promoting some higher heights toward AK using the December composite...he was asking about the vortex up there, not our temp anomalies. Phase 6 isn't that warm in December, it is in Jan/Feb.

You always hae to be careful with this stuff though. As we have said in the past, the MJO only has an influence of any real consequence if the wave is fairly robust. If it is weak, it is probably not doing much forcing.

That was going to be my next question was the strength and its effects? Thanks

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Phase 5 is still warm for us but it starts promoting some higher heights toward AK using the December composite...he was asking about the vortex up there, not our temp anomalies. Phase 6 isn't that warm in December, it is in Jan/Feb.

You always hae to be careful with this stuff though. As we have said in the past, the MJO only has an influence of any real consequence if the wave is fairly robust. If it is weak, it is probably not doing much forcing.

Ah, I misunderstood what he was asking there.

The MJO signal right now is quite weak and has been fairly weak since about late October...signal was much more strong during mid-October. I don't know where to find the Euro ENS for MJO forecasts but the GFS really doesn't have the MJO signal being all that strong too going down the road, in fact it seems like the consensus among the ENS is for the signal to get even weaker...which does make sense in a way b/c we're continuing to see cooling occurring across the tropical Pacific and those cold anomalies are really spreading in the western region.

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Ah, I misunderstood what he was asking there.

The MJO signal right now is quite weak and has been fairly weak since about late October...signal was much more strong during mid-October. I don't know where to find the Euro ENS for MJO forecasts but the GFS really doesn't have the MJO signal being all that strong too going down the road, in fact it seems like the consensus among the ENS is for the signal to get even weaker...which does make sense in a way b/c we're continuing to see cooling occurring across the tropical Pacific and those cold anomalies are really spreading in the western region.

GEFS bring the MJO into the COD...Euro ens strengthen it through phases 3-5.

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GEFS bring the MJO into the COD...Euro ens strengthen it through phases 3-5.

Wow...that's a pretty big spread there.

That would kind of suck if it did strengthen through phases 3-5, however, if that continued from phases 6-8 that wouldn't really be a bad thing.

Going to be crazy to see how much of a signal we will really see from the MJO going forward.

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This pattern has been persistent since about Nov. 1st. Imo, generally patterns last 4 to 6 weeks before they become unstable and shift into a different regime. Dec. 1st to the 15th would make sense in that paradigm because this has lasted since the October storm.

That makes sense and seems to be the timeframe everyone has discussed

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Interesting differences, hopefully NCEP is right

Pretty remarkable differences in the PNA forecast there.

If NCEP is correct there and we see a +PNA along with a weakening +EPO and -NAO that should spell big time potential I would think.

Keep the pattern active with sources for cold air to work in and we're good.

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Pretty remarkable differences in the PNA forecast there.

If NCEP is correct there and we see a +PNA along with a weakening +EPO and -NAO that should spell big time potential I would think.

Keep the pattern active with sources for cold air to work in and we're good.

FWIW, the euro guys bring the PNA to near neutral, but then it drops towards the end of the period as troughing develops in the sw. NAO is a non-factor imo. Transient NAO ridge is "bootleg" as Gibbs would say. Biggest factor is up by AK where we have ridging in the GOA that tries to drop the EPO, but it still has a lot of work to do.

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FWIW, the euro guys bring the PNA to near neutral, but then it drops towards the end of the period as troughing develops in the sw. NAO is a non-factor imo. Transient NAO ridge is "bootleg" as Gibbs would say. Biggest factor is up by AK where we have ridging in the GOA that tries to drop the EPO, but it still has a lot of work to do.

As long as we're not seeing a raging +EPO I think we should be fine. We really don't need to see a -EPO unless you want to see some brutal cold which is insignificant here.

If I remember correctly I think even the GFS ensembles drop the PNA negative, however, only slightly negative so the PNA signal won't be as strong either...taking this verbatim.

I still think going through the winter the NAO signal will end up being much more strong than any of the other signals and that will ultimately lead to us having an excellent winter here in New England.

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