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Winter 2014-2015 Pattern Discussion Thread III


BIG FROSTY

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Well, the EURO is a dud!!  I would say confidence is a little lower today for sure.  I always knew it was a long shot/ "thinking outside the box", but just because the players are around, they may not march to what we need.  The possibility is still there, but chances are lower today, IMHO

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Well, the EURO is a dud!!  I would say confidence is a little lower today for sure.  I always knew it was a long shot/ "thinking outside the box", but just because the players are around, they may not march to what we need.  The possibility is still there, but chances are lower today, IMHO

 

The worst part is on the surface it's not too bad....just can't get the southern stream going.  It's border line close to snow flurries in NC on this run past 200.

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The worst part is on the surface it's not too bad....just can't get the southern stream going.  It's border line close to snow flurries in NC on this run past 200.

Agreed..yall have the low level cold for sure.  Hell, there isn't any moisture around until everyone is above.  But, the euro is interesting, like you said, toward the end of its run.

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Ugghhh on the Euro MJO, looks like we are going to follow the cycle we did back in Dec....

 

That is worlds better than December and better than what the Euro was trending 5 or so days back...its now got some going into the COD and then coming out in 8-1-2...at the very least we may take the MJO out of the equation.

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That is worlds better than December and better than what the Euro was trending 5 or so days back...its now got some going into the COD and then coming out in 8-1-2...at the very least we may take the MJO out of the equation.

 

Good point, maybe it doesn't hurt us, but I like the GEFS better :-)

 

But, the BC version isn't as good.

post-2311-0-18390800-1420486626_thumb.pn

post-2311-0-74113700-1420486674_thumb.pn

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RAH still keeping an eye on this weekend:

 

.LONG TERM /FRIDAY THROUGH MONDAY/...
AS OF 300 PM MONDAY...

COLD CORE OF THE HIGH PRESSURE WILL BE SWEPT OFFSHORE RATHER QUICKLY AS
ANOTHER REINFORCING FRONT PUSHES THROUGH ON FRIDAY. TEMPERATURES WILL
MODERATE A BIT IN WESTERLY FLOW...WITH HIGHS FRIDAY AND SATURDAY
GENERALLY FROM 40 TO 45 DEGREES AS HIGH PRESSURE BUILDS ACROSS THE OHIO
VALLEY AND BEGINS EDGING RATHER OMINOUSLY DOWN THE EAST COAST SATURDAY

NIGHT. MEANWHILE...A SOUTHERN STREAM SYSTEM WILL BE EJECTING OUT OF THE
EAST PACIFIC AND ACROSS THE SOUTHERN GULF STATES LATE SATURDAY.
.. WITH
ISENTROPIC LIFT SPREADING HEAVY CLOUDINESS AND PRECIP ACROSS THE AREA
LATER SUNDAY...PEAKING SUNDAY NIGHT...AND WEAKENING ON MONDAY. FORECAST
SOUNDINGS ARE QUESTIONABLE THIS FAR IN ADVANCE...BUT INDICATE POTENTIAL
FOR A WINTRY MIX AT LEAST OVER THE CLIMATOLOGICALLY FAVORED NORTHWEST
PIEDMONT.
AT THIS POINT WILL INTRODUCE CHANCE POPS FOR LIQUID PRECIP IN
THE SUNDAY NIGHT/MONDAY TIME FRAME...WITH A KEEN EYE ON FORECAST TRENDS
OVER THE NEXT FEW DAYS.

 

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Ugghhh on the Euro MJO, looks like we are going to follow the cycle we did back in Dec....

Good point, maybe it doesn't hurt us, but I like the GEFS better :-)

 

All of the models, even the European suite have been guilty of trying to dump the MJO into the COD too quickly over the last week-10 days or so and the general pattern doesn't support the MJO diving into the COD this fast given the anomalous upper level convergence zone has continued to shift eastward in the Pacific, the minor stratospheric warming event, along w/ climatology which favors higher amplitude MJO during the JFMA period, that's not surprisingly phase locked w/ the naturally decreasing SST gradient across the tropical Pacific that reaches a minimum during the spring (this is also when the ENSO index exhibits some of the largest variance (hence the "spring predictability barrier") & the ITCZ becomes approximately symmetric about the equator during this time (which means WWBs (Westerly Wind Bursts) in the wake of the MJO have a more direct focus into the equatorial countercurrent & can thus allow for the MJO to have a larger impact on intraseasonal oceanic Kelvin Waves that ultimately have long-term consequences on the behavior of ENSO). I should mention also that global models often have lower skill in handling weaker MJO events (like this one) up to 2 weeks lead-time (& that's probably due to easier detection w/ concomitant variables U850/200 & OLR acting in concert wrt to each other) ,whereas over longer time periods, larger error growths may contribute to the observed similar skill levels in both initially weak & strong MJO events...

Prediction-Skill-of-WeakStrong-MJO-ECMWF

 

In fact, the ECMWF ensembles & the CFS ensembles are often too weak w/ MJO amplitude across the board (the Indian Ocean (phase 2-3) amplitude forecasts are absolutely atrocious), w/ exception to of course the CFS which often over amplifies Pacific MJO pulses (phase 6-8) as we're likely seeing at this point in time. Based on this information, a blend of the GFS & ECMWF solution is the most likely at this point in time w/ expectations of MJO propagation at least matching the previous cycle in terms of penetration into the central Pacific...

MJO-Amplitude-Observed-EPS-CFSv2-1024x67

 

Graphics courtesy of Hymei Kim et al "Predictability and prediction skill of the MJO in two operational forecasting systems"

https://www.wmo.int/pages/prog/arep/wwrp/new/wwosc/documents/PS133.03_S2S_Kim.pdf

 

I personally prefer to monitor the MJO using VP 200 provided by Dr. Ventrice instead of the EOF RMM/VPM diagrams, which are often turbid & look like a bowl of disfigured spaghetti (esp. in a weak MJO or w/ comparison to multiple global models),and I think you'll have a more unambiguous picture of the MJO at least if you have an idea of the general idea on where associated MJO phases are located...

MJO-Phases-Globe.png

OLR=shading (red shading=high OLR/convectively suppressed MJO phase, vis versa w/ blue) 850mb zonal winds (dotted contour=anomalous westerly winds, vis vera w/ full contours), (note how weak the OLR signal is outside the Indian-West Pacific Warmpool, this was a huge reason why Ventrice et al developed the VPM MJO index to use 200hpa Velocity Potential instead of OLR, while maintaining RMM's U850/200 components) (P=Phase)

 

MJO-Life-Cycle-U850-OLR-720x1024.png

 

 

IMO, it's fairly easy to see in this diagram, that the MJO is just entering phase 6

28.gif

 

 

plot_chi_tvalue_8pan_novmar.gif

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If I was the glass half full guy....this may be heading back to east coast trough with west coast ridge and with some blocking by last week of Jan.  Looks like it may be trying to boot the low from Greenland/Hudson Bay.

 

Personally I have been less than impressed with the LR models. Only saving grace is going to be next week and possibly next weekend. There is def. the chance to get better but I was certainly hoping to see some bigger changes taking place over the weekend since the cold air is now arriving. What a strange winter it's been for the models overall. 

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According to Larry's post...should be we JUMP up and DOWN for that?  That looks ok, if I am not mistaken..NOT perfect, but better than it has been.

 

 

Chris is echoing my thoughts pretty well here with regard to this brand new EPS MJO prog. Here's why I say this:

 

 Based on looking at 1,240 days of ATL JAN data since 1975 (i.e., a large sample), here is what I found for actual temp. anomalies as regards the MJO phases (note much colder in/near COD 7-8-1-2-3 vs. being clearly outside of it):

post-882-0-30630100-1420490698_thumb.png

 

 

 Now here is the just updated EPS mean prog. (as of 1/5)(it goes into COD 7 1/13 & is in COD 7/8 through 1/19):

post-882-0-29811500-1420490894_thumb.gif

 

 The new JMA ens mean is similar to the EPS as it goes into COD 7 on 1/12 and then into COD 8 on 1/13:

 post-882-0-51526900-1420491407_thumb.gif

 

 The new GEFS is not where I'd prefer to see it go vs. the EPS/JMA because it goes well outside the COD even though it shows it headed toward much better phases...again, focus on my chart in the 1st attachment in this post to follow what I'm saying. Though it can certainly be cold anywhere within the better phases or in any phase for that matter, the better phases have been much colder on average when the MJO has been weak (say, no further than just outside or within the COD) vs. being well outside the COD.

 

For example: Phase 8 (amplitude 1.25 to 0.50):

MB 48%, B 26% N 16%,  A 0%,  MA 10%

 

 You don't get nearly this cold a breakdown when the amplitude of phase 8 has been over 1.25. To the contrary, it is near neutral for phase 8 amp. > 1.25:

 

Phase 8 (amplitude 1.25+):

MB 20%, B 22% N 19%,  A 13%,  MA 26%

 

So, where would you rather be, where MB/B adds to 74% or where MB/B adds to 42%?

 

 Of course, the MJO is just one factor among many, regardless. It is just a tool to use with other tools. 

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18z GFS and PARA both have an icy solution for NC and what I would suspect would be a good portion of SC as well. 

Oh, I thought so...My thing is, if we have at least a run showing it a day...there is a chance something could happen..I know its a LONG shot for sure, but who cares...aren't all wintry events not good odds around the SE?

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FWIW to the naysayers and all that, as of 12z the GEFS plumes have around 8 members with winter weather of some sort (ice) into KCAE.  That's actually an increase.  Leads to believe that is a good chance for NC if moisture makes it up that way.

 

Of course, it will change.

 

Edit:  15 members of the EPS now for KCAE too.

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