griteater

I'd actually like to see the storm wave with less amplitude. More wave amplitude means warmer and farther north sfc low. We should have plenty of storm here, we just want to see the 50/50 low stronger / farther south / slower to escape off the E Canada coast - all equals colder

GEFS trend loop showing 50/50 low near Newfoundland is trending stronger. Accordingly, look at how the height lines just to the north of the Great Lakes and NY State trend flatter thru the loop - this is increasing confluence that is making the surface high trend stronger and farther SW....also with farther south low pressure. Kind of funny that this is 4-5 days out as so much can change. Going forward, we'd want to see the 50/50 low to continue to trend stronger and farther south, and for the storm wave tracking across the heart of the country to trend a little farther south and with a little less amplitude.

GEFS Mean was colder this run with 32 deg sfc along I 40.

00z UKMet

On the GFS, the wave was 3 hours slower this run, so you kind of had to compare, say, hour 90 from this run compared to hour 93 from the 18z run to see a more equal comparison (instead of comparing hr90 to hr96).

It’s extreme but not out of the question as things are trending a little south/colder at the moment

I'm a big fan of -AOs and -NAOs, but this consolidation of blue anomalies from East Asia to Alaska is not a good sight for getting cold down into our region (and most of the lower 48 as well). This is from the EPS Mean in 5 day increments from days 4 to 15. Maybe the one redeeming quality is that it consolidates some serious cold in NW Canada to potentially dislodge down the road.

It looks like this is going to be the second time that the GFS is more correct with respect to being less phase happy compared to the Euro and CMC. It never bought the idea of phasing the waves dropping down from the northern stream. It was also more correct with the previous storm that cut to the eastern Lakes and hit northern Ohio.

For Monday, to get anything more than light precip, it looks like the shortwave diving south out of MN needs to phase with the one tracking east out of Texas (this is all before the 3rd wave drops south out of the Great Lakes). The GFS/NAM/RGEM aren't phasing these first 2 waves. The Euro/CMC/UKMet/GFS Para/NAVGEM are phasing them.

Looking out in the long range, after this period of +PNA / Western North America ridging, here's a possible path that may give us or the mid-atlantic another storm threat... 1. Western ridge retrogrades west to the west coast or far east Pacific 2. One or 2 storms eject out of the SW on a track from northern NM to NYC in the Dec 12-15 timeframe. Ideally, the last system along this track would wind up strongly over the Northeast (with some Scandinavia > Greenland ridging kicking in). Cold air fills in behind. 3. Follow-on system would then kick out of the southern plains into colder air over the SE/mid-Atlantic in the Dec 15-18 timeframe. 4. Post Dec 18, it looks like we may warm up with negative height anomalies settling into Alaska

Ha, it looks like Hkywx is in mid-season form with his model predictions...he's had a number of good ones over the years. There are 3 separate shortwaves involved here and the 12z Euro didn't quite phase any of the 3, while this latest 18z runs phases them all together into a cutoff. Snow map here is thru the 1st half or so of the storm for SW VA and the northern mtns

Yeah I just chose 09/30 there because that was the date from the total snow map that you posted

Snowfall Percent of Mean from 09/30 to 12/01

raindance - you can get NAO data back to 1899 from climate data guide: https://climatedataguide.ucar.edu/sites/default/files/nao_pc_monthly.txt https://climatedataguide.ucar.edu/climate-data/hurrell-north-atlantic-oscillation-nao-index-pc-based

chubbs - that's cool that you pulled this data and used it against the period norms (1880-1910). Can you add March in there? I suspect it was quite warm based on the pattern.

^ Appreciate the feedback in the posts. Humbled.

Iso - good read as usual. Thanks for continuing to post these (same with others posting outlooks).

Apologies. I just uploaded it to Google Drive, so hopefully that doesn't cause issues as well. Link in the original post is updated. I need a blog site, but just have never gotten around to it. Thanks. https://drive.google.com/file/d/1S-f_HQdrNYZkrRw_6YhkFCkASa0WAZpa/view

Posted my winter outlook here: https://www.americanwx.com/bb/topic/54042-griteaters-winter-outlook-20-21/

Posted my winter outlook here: https://www.americanwx.com/bb/topic/54042-griteaters-winter-outlook-20-21/

Griteater's Winter Outlook (20-21) Link to PDF: https://drive.google.com/file/d/1S-f_HQdrNYZkrRw_6YhkFCkASa0WAZpa/view Also posted on Twitter: https://twitter.com/griteater/status/1326893718536859649?s=20 Top Pattern Analog: Winter of 1893-1894

It's likely that more steady positive SOI numbers will return once this MJO wave moves back into the La Nina like phases (3-4-5)

^ Raindance - it's just one piece of the puzzle. You need to be able to predict whether the North Pac ridge will be poleward (North) or suppressed (South)...and whether it will be biased to the east or to the west (from a seasonal standpoint). You also need to be able to predict what the AO/NAO are going to do. All of that impacts the forecast. For example, for 16-17, if you could forecast that the N Pac ridge was going to be biased to the NW and that the AO/NAO were going to be positive, you'd get the general idea correct of cool in the PNW and warm in the eastern half of the U.S.