griteater

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.

Just light rain now

It’s sleeting here at my in laws, 3500 ft on a ridge above Spruce Pine

The clouds this morning have that angry gray, approaching Miller A look to them

Feb 1973 - Miller A for sure, with big, sprawling high to the NW. Not much of CAD signature. Feb 2010 SC storm was similar, but didn't even have a strong high to the N or NW - just a super suppressed storm track under a big -NAO

It depends on the setup. If talking about CAD with a retreating cold air mass, then yes, that's a setup for ice. But ideally for snow, we want to see high pressure in all directions to the north (NW, N, NNE - "banana high"). CAD can be critical for those along the precip type transition line (I-85) in terms of driving cold air in the lower levels farther to the south. 2 of the all-time great cold snowstorms for parts of the southeast had big time CAD signatures, Feb 1979 and Jan 1988

Haven't seen the end of a model run look this bad since the winter of 11-12

There’s no shortage of examples, but yeah, that’s one

Bob - if you need more members to scour thru, you can get all 20 of them here, ha - http://mp1.met.psu.edu/~fxg1/ENSHGTWIDE_18z/ensloopwide.html

The scars of 12 inch Euro snow maps turning into a 1/2 inch of slop on the south sides of Greenville - Charlotte - Raleigh run deep in here Stanton. It is what it is. Anyway, the GEFS in never never land is moving in the right direction.

UKMET/EURO blend when different from the others is tough to beat

Yes, and that 18z GFS run has some weak phasing at just the right time to eek out some frozen precip. CMC run was similar. Problem is, the Euro and UKMet pinch off the wave and send it into the deep south without reinforcing height falls coming in from the northwest. I would think the thing to look/hope for would be a trend to a little sharper ridge out west behind our storm wave, combined with the 50/50 low complex over SE Canada not moving out as quick - so, more amplified flow and less progressive

Actually, the image on the right (^ above) is showing winds out of the SE at 850mb which is fine (that image on the right shows 850mb temps and winds, with sfc high and low location). The weak damming there has light NE winds at the surface...anyway, cold air is lacking, but not impossible for this to work if the timing improves...I'm not a fan though

Cold air availability is sorely lacking...and winds with any kind of southerly component at the surface are a big no-no leading into a winter storm (SE winds in North Carolina in this case).

Personally I think the GFS is just pulling us in and playing with us like a casino, but the model is throwing out interesting looks nevertheless. The one thing that stands out about the GFS is that it is deeper with the upper low/wave than the other models, and thus, colder. Here's tonight's UKMet at hr144 - the wave is closed off there in Texas, but it's not very strong / not very deep...and the high pressure strength / positioning isn't as good due to its upper level pattern across central and eastern Canada

The key idea of us moving to a cooler pattern was for the bulk of the closed low (or lobe of the Tropospheric Polar Vortex) over central Canada moving into southeast Canada. With the bulk of it instead moving to Alaska, we are left with a developing, mild, west to east zonal pattern. BUT, over the past few weeks, each time the models move toward a mild look in the medium and long range, they flip and move back toward a cooler look, and vice versa.

From the 12z Euro Op run

While the GEFS has backed off a little with it's setup for Dec 20-21, the EPS has gradually improved. Here at day 8, it has a nice, sprawling, closed 500mb low over SE Canada (1st image) with surface high pressure behind it, north of the Great Lakes (2nd image). The potential southern stream wave is in W Texas - though it is low amplitude over the southeast due to the suppressed height field along the east coast. Needs some work, but a decent look here. The most important piece here is getting the consolidated closed low over SE Canada in place.

Moving ahead 10 days (lol)....wow at this 00z run of the GFS...just a textbook 500mb evolution and Miller A snowstorm...split flow wave enters the U.S. in Baja and treks due east, wow

The GEFS is trending nicely (including the 18z run). However, the EPS and CMC Ens aren't dropping all of the closed upper low over North Central Canada down into SE Canada, and not showing nearly as nice of a Davis Strait block & 50/50 low couplet...so that needs to change. I did see that the EPS Control run was quite suppressed and cold along the east coast.

^ Yeah guys, the GEFS at 500mb shows some nice features here. Ideally for a colder and more suppressed setup for us, the 'inflection point' or transition between the negative anomalies over SE Canada and the positive anomalies over Greenland and Davis Strait would be closer to the U.S., but it's still pretty good here overall, and it's the type of setup that could trend south and colder over time due to the block (unlike the setup for our storm tomorrow). Here's the storm traversing the south with the freezing lines on the ensemble mean draped thru parts of TN and NC

You've heard of retrograding Greenland blocks that slow the flow down and send everything south...well, here we have a closed low that retrogrades west across northern Greenland, and there appears to be a bit of a fujiwhara effect where our trough over E Canada that is supplying the cold air with the surface high behind it is whip lashed forward into the North Atlantic amidst a super high +NAO regime. Any wintry weather in this split-flow setup comes down to impeccable timing (about as good a timing as you can have if it were to work out)

This is all well-stated Disc. Here is the latest NAM at 925mb showing the wedged in cold banking up against the Blue Ridge