griteater

Yes that was classic split flow to a T...hope we get a shot at seeing that down the line

Those MJO plots tend to have that hook on the end. Here are stats from DonSutherland - "Historic experience with the MJO following its reaching Phase 4 at an amplitude of 1.500 or above during the January 5-20 period (as occurred recently) sees the MJO progress into Phases 7 and 8 (88% cases)" What I suspect we will see is something along the lines of the CFS, minus the hook on the end...that is, into Phase 5 at high amp, into Phase 6 at moderate amp, into Phase 7 at low to moderate amp, into Phase 8 at low to moderate amp, and into Phase 1 at low amp. The bigger question is will the atmosphere respond to the MJO tropical forcing in a manner that is consistent with prior cases. It doesn't always respond (just look at last Februrary). The MJO Seasonal Cycle tool from Paul Roundy is really good at showing the typical pattern produced by the MJO Phase and time of year - http://www.atmos.albany.edu/facstaff/roundy/waves/rmmcyc/index200reg.html

CPC mentions the nagging +NAO...I know we've seen cases in the past where we get the big western ridge, but the cold isn't able to drive way south in the means due to a +NAO. Prognostic Discussion for Week 3-4 Temperature and Experimental Precipitation Outlooks NWS Climate Prediction Center College Park MD 300PM EST Fri Jan 10 2020 The forecast 500-hPa circulation (blend of the global ensemble means) is consistent with the forecast during the preceding Week-2 period, showing the evolution from a negative PNA pattern to a negative NPO-WP pattern that favors more widespread below-normal temperatures over the CONUS. While this is broadly consistent with forecast MJO propagation, the forecast circulation fields also indicate the persistence of the low-frequency positive NAO pattern that has been observed over the past several weeks. This continued +NAO is not consistent with forecast MJO evolution. https://www.cpc.ncep.noaa.gov/products/predictions/WK34/

CPC Week 3-4 Forecast

Here's what the MJO looked like back in November when it was chilly

MJO Forecast trend on the GEFS... Quality post from @donsutherland1 (recommended reading) - https://www.americanwx.com/bb/topic/52870-january-2020-general-discussions-observations-thread/?do=findComment&comment=5418232 "Key Points (from Don): 1. A preponderance of data is pointing to the return of winter in the East. 2. January could close with a sustained cold pattern that could continue into at least part of February."

Recent trends on the CFS Monthly for February

Best run I've seen of the GEFS in the extended. Core of the cold air is in the lower 48

With the MJO making it's run out into the Pacific (phase 7-8), it does make sense that we would see better chances at western ridging. So, that's step 1. These last 2 runs are on the extreme side, so hard to count on that...but it shows the potential

GFS builds the western ridge even more out in time. That's 2 cold runs for sure.

Nice western ridge on the GFS...fun to look at for now anyway

00z GFS going cold again in the extended, but a little quicker this run...and it has a significant winter storm in parts of the SE from Corpus Cristi / Houston / New Orleans / Montgomery / Charlotte

It has the 850 zero degree line in the southern Gulf of Mexico - fun

GFS happy hour is dropping the mother lode of cold into the lower 48 late in the run

CFS Weeklies for weeks 3-6 (Jan 23 - Feb 20)

EPS Day 10-15 Mean (850mb Temp Anomalies)

This GFS run from hr200 to hr324 gave me a flashback to the early Jan 2017 storm look where it tucks part of the upper wave in the NE Pac back west, but dives a piece of it southeast out of the Pac NW into the cold air over us

@Tom Niziol - Only 28.1% #snow cover across the US right now, have to go way back to 2012 to see less on this date at 12.9%

The PNA Index from now til Jan 14th

Based on what we’re seeing on the modeling and our current climate, nothing would surprise me on the warm side for January. Things like top 5 warmest January ever / warmest January day ever, etc.

Well this winter certainly isn't going as I expected. Kudos to @Isotherm as his winter outlook ideas have performed well to date. As CPC notes in the previous post, we need to see the tropical convection move away from the Indian Ocean and Maritime Continent and move into the Western & Central Pacific in order to give us a better shot at stirring up the Pacific side pattern. Climo-wise, February gives us our best shot at seeing a -EPO/+PNA pattern during +ENSO winters. Last winter (also +ENSO), we saw a -PNA pattern in February. As @raindancewx has noted on the main board ENSO page, one thing that has been different this winter compared to last is the SOI. The SOI was +9.3 in Dec 2018 and neutral to positive from Oct-Dec (atypical of +ENSO winters). The SOI was -5.5 just this past Dec, and also negative in Oct & Nov (more typical of +ENSO winters). That may be one indicator that we will see a more typical +ENSO response in February. 2 flies in the ointment would be: 1) Convection not moving out into the Pacific, and instead, hanging around in the Eastern Indian Ocean and Maritime Continent. That would likely lock in the warmth going foward; and 2) The continued +AO overwhelming any Pacific side shake up. We can see here the CFS model showing the tropical convection (-OLR) moving away from the Indian Ocean and Maritime continent (40E to 140E) and consolidating in the W Pac & C Pac (150E to 150W) in the second half of January. Accordingly, the CFS has been trending colder for February, with a deeper eastern trough in recent runs (trend on last 8 runs shown): That's just one model though - who knows if it is right, but it would fit well with +ENSO climo. Also of note is Paul Roundy's Experimental MJO Forecast Tool which shows the tropical convection kicking out into the W and C Pacific and a colder pattern in the eastern U.S. by early Feb. For reference, see: https://twitter.com/PaulRoundy1/status/1213065361727393798 http://www.atmos.albany.edu/facstaff/roundy/waves/rmmcyc/indexmjo.html

Here's the text from CPC to go along with those maps... Prognostic Discussion for Week 3-4 Temperature and Experimental Precipitation Outlooks NWS Climate Prediction Center College Park MD 300PM EST Fri Jan 03 2020 Week 3-4 Forecast Discussion Valid Sat Jan 18 2020-Fri Jan 31 2020 The global tropical convective pattern remains weak, with ENSO-neutral conditions prevailing, an incoherent MJO signal, and a decaying Indian Ocean Dipole (IOD). Therefore, little contribution from the tropics to the downstream midlatitude pattern during the Week 3-4 period is evident in the statistical guidance. Dynamical models almost uniformly favor renewed MJO activity, however, with the enhanced phase crossing the Maritime Continent over the next two weeks at a high amplitude on the RMM-based MJO index. The weakening IOD signal effecting a change in the base state may partly explain the forecasted high amplitude signal, but should a robust MJO event develop and propagate to the Pacific, it could help promote a substantial late winter pattern change over North America. These impacts would occur largely after the Week 3-4 period.