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Pattern September Somnolence

The good news is, this winter we're not going to have to worry about the warm nose or 33-34 and rain. It's going to be in the 80s all winter. :(
It’s 67 degrees here at 2:43PM and our average high is 80. I get that people south of us are still hot but that fall front you asked for is here is it not? The extended looks like below avg highs for a bit also although our avg lows look to be above. I will admit our avg lows have basically been above normal since late May other then literally 4-5 nights.
 
The models are increasing tropical forcing from the Northeastern Pacific (phase 8-1) throughout the remainder of September into early October. Strong NE Pacific forcing (via large-scale heat/momentum fluxes from convection associated w/ both the monsoon & TCs) during the summer strengthens the SE US ridge, hence the pattern change looks more lackluster lately.

ECMF_phase_51m_small (1).gif

ECMF_phase_51m_small (2).gif


Seasonal changes in the jet as well as the locus of phase 1 forcing shifting from the NE Pacific to the dateline of the Pacific in addition to the continued decay of the Tibet Anticyclone (into an even more anomalous upper level trough) as the Indian Monsoon relents, completely alters the strength, intensity, and the waves that interact w/ and emanate from this forcing. Thus, once the CA monsoon ends by late fall, and the SSTs in the NE Pacific aren't sufficiently warm enough to readily sustain convection, the pattern response here in the SE US turns into one that favors colder than average temperatures, troughiness, and a strong subtropical jet by mid-late winter, all of these usually favor winter storms.
200 hPa height anomalies (contours), wind vectors (arrows), and OLR (shaded)

figreg200280_1.png
figreg20030_1.png
 
Phase 8-1 MJO (Eastern Pacific/W Hem) in late September & October actually strongly favors a SE US & the signal is robust beginning in late September, including the first half of the month dampens the signal.

OctoberPhase8gt12mT.gif

Zoomed in version of the Phase 1 200 hpa height anomalies centered on October 8th via Paul Roundy I showed earlier.

Screen Shot 2018-09-22 at 4.41.46 PM.png

http://www.atmos.albany.edu/facstaff/roundy/waves/rmmcyc/index200reg.html
 
Decide for yourself if you think the 500mb height anomalies on the GEFS for 12z September 28th fit the 500mb Phase 8 MJO analogs centered on that date.

gfs-ens_z500a_namer_25.png



(Zoomed in)

View attachment 6541
(Full size)
fig270_8.png

The following week, the signal very weakly suggests a 500mb SER.
fig280_8.png

MJO is clearly forecast to be in phase 8 and have been there for quite some time.

diagram_40days_forecast_GEFS_member.gif
Watch how in winter, the MJO lives on the opposite side of the graph. :(
 
Ehhh no. The jet extension in the NE Pacific from preceding TC activity in the Indian Ocean & WP leads to that pattern on day 6 of the GEFS, the signal from the MJO (which responds to the Central America monsoon) doesn't actually appear and is masked until later in the period. The extratropical response to diabatic heating in the tropics isn't instantaneous once the MJO emerges w/ >1 amplitude from the COD. The EOFs used to calculate the MJO are projecting onto a convectively coupled Kelvin Wave being slowed by a strengthening Central America monsoon & a base state that already favors strong EP convection.
 
Ehhh no. The jet extension in the NE Pacific from preceding TC activity in the Indian Ocean & WP leads to that pattern on day 6 of the GEFS, the signal from the MJO (which responds to the Central America monsoon) doesn't actually appear and is masked until later in the period. The extratropical response to diabatic heating in the tropics isn't instantaneous once the MJO emerges w/ >1 amplitude from the COD. The EOFs used to calculate the MJO are projecting onto a convectively coupled Kelvin Wave being slowed by a strengthening Central America monsoon & a base state that already favors strong EP convection.
El NINO is still forecast right? Are things on track so far as in modiki?
 
El NINO is still forecast right? Are things on track so far as in modiki?

Yes for El Nino. Besides the firm support already from the last several months of +0.80+ subsurface, the subsurface has actually been warming even further the last few weeks. It appears to be near +1.00 now and warming even more. With this latest warming, we’re just about to the point where there are no analogs that didn’t end up as El Niño by late autumn. The lone holdout had been 2012, but it didn’t warm to +1.00 in the subsurface around now. Instead it cooled from +0.80 in August to +0.40 in September. So, we can now say goodbye to 2012 as an analog and hello to El Niño in all likelihood. Keep in mind that this is following the Eurosip forecasts back to May, which had a hiatus in 3.4 SST warming in late summer before a resumption starting around now.

Modoki? Looking at where the subsurface warmth appears to be headed toward the surface and considering the TAO based buoy map, that is suggesting warmth concentrating more in the W portion than E portion of 3.4 currently. That tells me Modoki looking good.
 
Well, as I have decided to postpone my relocation to California until Spring, looks like I'll have another winter here in North GA....lol. With that said, the models were showing a pretty decent cool down toward the end of the month but it looks like that is getting pushed back and back each run lol. But, honestly that is usually the norm this time of year.... just hope the heat relaxes a bit as it's been hellish with the heat this month! #ReadyForFall #ReadyForWinter
 
Phase 8-1 MJO (Eastern Pacific/W Hem) in late September & October actually strongly favors a SE US & the signal is robust beginning in late September, including the first half of the month dampens the signal.



Zoomed in version of the Phase 1 200 hpa height anomalies centered on October 8th via Paul Roundy I showed earlier.



http://www.atmos.albany.edu/facstaff/roundy/waves/rmmcyc/index200reg.html

Good to see ph1 temps do moderate. Hopefully as we get into October we can see atleast some seasonal temps.
OctoberPhase1gt12mT.gif


Screen Shot 2018-09-23 at 9.42.41 AM.png
 
On the warm side of the wedge this morning. Full sun and warming quickly.

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El NINO is still forecast right? Are things on track so far as in modiki?

A moderate downwelling oceanic Kelvin Wave is currently crossing the Pacific & reinforcing an already suppressed thermocline, we should see an El Nino out of this, potentially even a low end, late blooming (late winter/spring) moderate one given how suppressed the thermocline already is. The decay of the Eastern Hemisphere monsoons and retreat of the Intertropical Convergence Zone towards the equator will aid in NINO growth as we get into the fall & winter. The cross-equatorial flow induced by the strong E Hem monsoons this summer have likely stifled this El Nino, once they go away subseasonal forcing and the low-level wind envelope associated with it will become more axissymetric wrt the equator. (there's plenty of literature on this subject) The WWB that's coming in the next few weeks due to the aforementioned Convectively Coupled Kelvin Wave interacting w/ a slightly positive ENSO base state & central America monsoon will further suppress the thermocline. The Central America monsoon and +ENSO base state will decelerate and amplify the eastward propagating CCKW by increasing the intensity & coverage of convection within the MJO's envelope, causing some "spectral leakage" of the Kelvin Wave into the MJO's bandwidth. What this actually means is the MJO will move out of the "circle of death" even though it's really not a "true" MJO event in the sense that there's little slower, and more coherent eastward propagation of the subseasonal convective forcing from the Maritime Continent & West Pacific to the Western Hemisphere.

wkxzteq_anm (1).gif


Notice how the Kelvin filtered -VP200 anomalies (the contours) dissipate over the eastern Pacific's longitude, while the GFS might be overdoing this, you can see there's now a lower frequency/slower moving component to the -VP200 anomalies that almost become quasi-stationary between 120W and 60W next week. This is the spectral leakage of the CCKW onto the MJO that I'm talking about above, it's important to understand what portion of the seasonal cycle we're currently in & what the lower frequency, quasi-stationary variability looks like (ENSO for ex) because these features will play a significant role in determining the MJO's phase speed and amplitude over certain areas of the globe.

vp200.GFS.anom.KELVIN.5S-5N (3).png
 
On the warm side of the wedge this morning. Full sun and warming quickly.

Sent from my SM-G955U using Tapatalk
Welcome to every winter storm ever talk! From mby!:(
 
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