• Hello, please take a minute to check out our awesome content, contributed by the wonderful members of our community. We hope you'll add your own thoughts and opinions by making a free account!

Pattern Jammin January 2023

f647a0a0d8b87b6251bc7b25a3f252f6.jpg

GFS wants pretty significant severe mid week next week


Sent from my iPhone using Tapatalk
 
The period with highest potential IMO is after this squeeze play occurs between the western ridging and Greenland ridging, which forces the TPV lobe down into Hudson Bay, shown here on the EPS for Jan 23-29....which pushes both cold air and the storm track to the south

2m56IDo.gif



The Euro Control Run that @Robert West posted with the deep south snow does this beautifully here Jan 25-30

TF0Qujn.gif


hTDXLgt.gif



Prior to the TPV dropping south, I think any wave that amplifies enough to generate a storm is going to cut too much to our NW.

Now, it's certainly possible that the squeeze play isn't as sharp as shown on the EPS, and the TPV doesn't drop south as much, and we end up with a continued Ohio Valley or Iowa Tarheel storm track during this preferred timeframe.


Lastly, I wanted to bring up a comparison between this January and last January. With respect to the Pac Jet and the overall pattern, there are some key similarities and differences between the 2. Last Jan, the Pac Jet over-extended in early Jan (mild period), then retracted in mid Jan, then extended again to a good location in mid-late Jan (cold period). Sound familiar? We are seeing a very similar evolution this January with the exceptions being: 1) the Pac Jet extension in early Jan this year was even stronger (Super El Nino like), and 2) as we go into late Jan this year, we are going to see the MJO / tropical forcing become active in the Indian Ocean...that was not the case last year whereby the -VP signal of the MJO was moving out into the Pacific during mid to late Jan.

So, last year's tropical forcing supported maintenance of a nicely extended Pac Jet that produced the necessary western ridging that led to the cold and wintry period in mid-late Jan. In contrast, we are likely to see a quick retraction of the Pac Jet as we go into late Jan which would affect things into early Feb

On the positive side, we should have increased support for a period of Greenland ridging in late Jan compared to last year based on the forecasted Scandi ridging that will want to retrograde to the west given the overall weakness in jet momentum in the pattern during that timeframe.
 
Last edited:
griteater said:
Trend loops of the EPS for Jan 27 and Jan 29. Improvement shown over Iceland / Greenland and with the TPV dropping south in Canada

ANUoRyK.gif


hHwEiiR.gif
Click to expand...
Hence why blocking is often associated with the action of “squashing” the SER as seen by the trend loops. Hopefully we can maintain this look for the late January period
 
Webberweather53 said:
Much like I did around this time in December (linked below), here's my general sentiment on the rest of meteorological winter.

Again, looking at the big, general picture, don't worry about any details this far out. Only concerned about the planetary-continental scale wave pattern evolution & tropical-extratropical subseasonal coupling processes, not individual storms, not rain/snow p-type maps, etc.

From a tropical forcing perspective & using weekly model forecasts + Nina climatology & analogs as a basic guide line (not actual forecast), this is what things generally look like to me. Tropical forcing will be very dominant over the next several weeks as the MJO &/or Kelvin Waves in the E Hem superposes onto La Nina (gets an assist from the SSWE in the form of an enhanced Brewer Dobson Circulation & we begin to approach the annual peak in MJO amplitude in Feb-Mar).

The big -EAMT event we saw this past week set this pattern evolution into motion and the Pacific jet retraction will get handed off & further reinforced by the MJO as we enter February, leading to a prolonged period of -PNA/SE ridge pattern in the first half-2/3rds of February.

Thus, I think we'll probably go from this central-western weighted trough & southern Canada vortex late month w/ occasional bouts of cold + an outside chance of a CAD event, to a more traditional -PNA in the first week of February that probably shuts down any real chance we have wintry weather, unless we see the 50-50 low go completely crazy like a few EPS & GEFS runs have hinted at.

Thereafter, as we get into the 2nd week of February, I suspect the SE US ridge will actually amplify + flex up the East Coast as the -PNA retreats further into western Canada, yielding a potentially very/unusually mild pattern for much of the E US (not just the SE US this time). I think this pattern will try to persist into at least the 3rd week of February (Feb 14-21), even as the MJO (or whatever comes of subseasonal tropical forcing) enters the West Pacific but by then, I believe we'll see the large-scale puzzle pieces begin to start shuffle around, eventually yielding a potential +EAMT &/or MJO-induced Pacific jet extension sometime around Feb 20th or so.

Eventually, I think that coupled with rapidly shortening jet wavelengths will cause a lot of reshuffling of the circulation pattern over the N Pacific + N America, allowing us to shake off this -PNA/SE ridge pattern sometime around the last week of February & transition to a favorable look for cold/snow right at the tail end of February &/or early March, a time of the winter where we tend to see the most big dog winter storms per capita.

Given that we're not only in a La Nina but would be closing in on a time of the year where the MJO tends to be the most amplified (& therefore slow), plus potential interaction with a SSWE &/or ENSO, there's a risk this overall timeline on the back end of February gets pushed back some closer to early March, but not favoring that scenario for now.

I think these RMM regression maps from Paul Roundy get the general idea generally right here.

Late January: (Very) marginal pattern for cold/snow w/ mean trough centered to our west w/ trough south of Greenland. Slight chance of a CAD event.
Early-mid February: Transition to a more canonical La Nina -PNA/SE ridge pattern w/ the SE ridge flexing up the East Coast, & getting warmer (anomaly wise) as time progresses during this period.
Late February: +EAMT &/or MJO-induced jet extension flips the Pacific pattern, pattern reshuffles over N America in response to that & seasonal changes to the jet stream. Favorable pattern for cold/snow tries to return during the last week of Feb or so.
Early March: A favorable pattern for cold/snow seems most likely to return during this time period. Fighting against increasingly unfavorable climo as early March turns into mid-March. Suspect after our "false spring" in early-mid February, actual spring may get put on hold for a bit this year once we flip the calendar to March.

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




View attachment 130404


View attachment 130414


Here are the JMA MJO composite OLRa & VP200a for each MJO as a rough reference guide to compare w/ against the extended GEFS above.

https://ds.data.jma.go.jp/tcc/tcc/products/clisys/mjo/composite.html

View attachment 130420
Click to expand...

Today’s Euro weeklies look very similar to the animation I showed earlier this morning from Paul Roundy’s site.

Also notice the Aleutian trough returning ~Feb 20.

E17148DF-4038-440A-BD1E-DC3E754E08C8.gif
 
You must log in or register to reply here.
Back
Top