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Mid to late February Pattern Discussion...stormy or end of winter?


ORH_wxman

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The cold bias doesn't exist per some posts here.

 

I think in the 8-15 day range this year most of the time it's pushed the cold air too far SE.  I believe the GEFS in particular still have a documented bias in the NE quadrant.  Both would favor the model pushing storms a bit too far east.

 

JMHO, we may be battling mess in this next pattern in the CP

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I believe 100% we're going to see an increase in southern disturbances. If I had to guess though the CP is going to see some warmer air along with at least some of them.

That goes without saying..but still better than cold/dry. feb climo down here will help the coast out anyway. I'll take my chances with an active pattern.

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Yeah that's how you should approach it. Of course it all won't be frozen, but in order to get any snow, you need the storms!

 

It's all long range but the 18z GFS would better illustrate what I was mentioning.  Back the cold off a little and there's more room to take the inside routes.  IMO one of the options on the table is a flip the other way now to storms but wet.

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• The MJO remained active over the past week but observational indicators continued to become 

less coherent. The enhanced convective phase is centered across the western Hemisphere.

 

• Other forms of subseasonal variability remain active  and have contributed to making the MJO 

signal less clear. This is expected to be temporary and dynamical model MJO index forecasts are 

in good agreement of renewed eastward propagation during the period.

 

• Primarily based on dynamical model MJO index forecasts, the MJO is forecast to remain active 

with the enhanced convective phase shifting to Africa over the next 2 weeks.

 

• The MJO favors enhanced rainfall across parts of the south central Pacific Ocean and suppressed 

convection for the eastern Indian Ocean (Week-1), the Maritime continent (Weeks 1-2) and the 

western Pacific (Week-2). 

 

• For the U.S., the MJO favors, on average, split flow and ridging across the western U.S. and a 

mean trough across the east until about mid-February. The MJO would also favor an active 

southern jet during this similar period. Thereafter, the MJO would support a tendency for a mean 

trough to develop across the western U.S. near the last week of February.

 

...I like their use of terms such as "favors", and "tendency", because the MJO is just one factor, and can be muted down to almost no observable correlation on the pattern if there our counter-balancing exertions in the circulation system overall - for example, when the WPO is out of phase with the MJO, good luck -  It's hard to introduce tropical forcing to the middle latitudes if their is no channel.  

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Same thing on this 00z op. GFS, 180 hour depiction that's been afflicting this mid winter;  ridge too far west, flow splits, lowering heights dig SW, height build over the Gulf, N stream then brings cold heights, causing too fast of a flow.  This one panel is kind of microcosm that illustrates the wave interference of the whole.  Split flows have produced in the past; mix events, ice storms, overrunning, ...etc.  Why this year hasn't would require a case by case study.

 

gfs_namer_180_500_vort_ht.gif

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Same thing on this 00z op. GFS, 180 hour depiction that's been afflicting this mid winter;  ridge too far west, flow splits, lowering heights dig SW, height build over the Gulf, N stream then brings cold heights, causing too fast of a flow.  This one panel is kind of microcosm that illustrates the wave interference of the whole.  Split flows have produced in the past; mix events, ice storms, overrunning, ...etc.  Why this year hasn't would require a case by case study.

 

0z GGEM is a toaster bath.  Weak system on the 6th same old same old....next two are cutters.  The 2/8 system cuts across southeast Canada or northern New England...warm south of CNE, the 2/12 is a super cutter like the other day, going 987 way into Canada.

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mike ventrice posted

"As most are aware, there is incredible model volatility between the GFS and ECMWF in the upcoming two weeks. I've been leaning towards a warmer solution for much of the NE US, consistent with the EC runs, however GFS is showing a large trough diving down the central US interior... sliding eastward thereafter. After a bit of digging around, I just noticed that the GFS is holding up a strong eastward propagating convectively-coupled Kelvin wave over S. America in the next week...

 

The easiest way to illustrate this is a time-longitude plot of 850 hPa Velocity Potential anomalies. Here the warm colors represent low-level convergence. You can see a fast moving positive VP850 anomaly from the dateline on Jan 28, and currently is located at approx 60W today. Once in GFS-forecast mode, it keeps this signal stationary, with NO eastward propagation thereafter.

 

 

vp850.anom.30.5S-5N.gif

 

 

In MJO-phase space his type of evolution would suggest a hold up in phase 8... which you can see in the diagram below.

 

NCPE_phase_21m_full.gif

 

I'm fairly confident this type of MJO-evolution will not occur, and we should see a continous eastward propagation through the upcoming week, with a decent signal in MJO-phase 2-3 by Feb 7-10-> consistent with ECMWF Ens predictions.

 

ECMF_phase_51m_small.gif

 

 

So that being said... I'm leaning towards more of a EC outcome in extratropcal circulation patterns for upcoming few weeks."

 

i'm fairly confident this winter blows and will continue to blow

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