GaWx

When I see the model consensus giving St. Louis a good shot at getting <0F for lows and barely above +10 for highs and the airmass has a strong +PNA to steer the bulk of the airmass down quite far but at the same time running into a moist WSW H5 flow (split flow), that combo is usually a good benchmark for good wintry mischief potential in the SE soon afterward.

So, 1st 3 major 0Z runs (Icon, GFS, CMC) all have a low to mid 1050s high plunging down Feb 16th-18th bringing down absolutely frigid mid -30s 850s into ND/MN (nearly as cold as the plunge of Jan 19-20) thanks to the tale end of a -5 AO steered by a strong +PNA during moderate MJO 8. This is a very rare setup in mid Feb, especially in La Niña. We should be very thankful for having this opportunity.

Nice hit in much of SC to SE NC:

2nd wave:

Barney’s in charge in the Plains so far on 0Z GFS thanks to a big 1050 mb high plunging down: colder than recent runs

Could we be looking at Brick Storm #2? Wx Channel already renamed 1/21-2 storm as Brick #1. You’re world famous now!

No Euro 12Z yet, but new weeklies (0Z based) just came out: This remains the week with the best opportunity for a significant SE wintry event, Feb 17-23: H5: 2m: qpf:

The last two 12 hourly UK ens runs have trended toward more cold air getting into SE from the Plains Arctic high along with the surface low’s mean track being further SE. Two runs ago, the mean low was tracking inland into N FL vs the current run’s 100 miles offshore the SE coast: https://www.pivotalweather.com/model.php?m=mogrepsgens&p=sfcmslp-meanmem&rh=2025021112&fh=198&r=us_se&dpdt=&mc=

All 5 periods of a sub -5 AO in Feb back to 1950 had wintry precip on or near those dates in RDU and/or GSO: 2021, 2010 (two periods), 1978, and 1969 fwiw. 12Z Euro still not started which means it’s at least 35-40 minutes late getting started.

I don’t know. Potentially?

1. 12Z Euro running late on WB. Weenie induced slowdown? 2. 12Z GEFS 10:1 snow:

12Z UK has surface low moving into W Gulf SE of Brownsville heading ENE with 1049 Arctic high over SD: https://www.pivotalweather.com/model.php?m=ukmo_global&p=prateptype_ukmo-imp&rh=2025021212&fh=168&r=conus&dpdt=&mc=

12Z GEFS impressive cold preceding storm possibility:

Then consider starting the thread, Mr. Tamland! Holy Barney on 12Z CMC! Is it overdoing it?

TX/LA:

And then another wintry threat follows Barney on 12Z GFS

Barney cold follows this on 12Z GFS:

Going back to 1950, I couldn’t find a single La Niña Feb out of the 26 of them that had both a +PNA and a -AO! So, 2025 will end up quite unique in that regard.

RDU La Niña 4”+ snows Feb 15-28: 2/16/1996: 5.6” 2/23-4/1989: 4.2” 2/17-8/1989: 4.9” 2/25/1894: 5.0” GSO had 5.7” just after Feb (3/1-2/2009). Also, other areas like ATL and Athens had a big snow 3/1/2009. Athens, GA: 2/23/1989: 4.6” 2/24-5/1894 (this also hit ATL) So, 2009 (Mar 1-2), 1996, 1989, and 1894 had major SE snowstorms Feb 15th-Mar 2nd in La Niña in SE US. RDU had 2 big snows later in Mar in La Niña: 3/10/1934: 8.0” and 3/25-26/1971: 5.3”

Below is the latest GEFS +PNA prediction. If it were to verify closely, DJF of 2024-5 would end up at or very near the highest +PNA on record (back at least to 1949-50): If the above were to verify closely, I’d project Feb PNA of ~+1.60, which would mean DJF PNA of +1.45! Current highest on record are these: 1976-7: +1.43 2015-6: +1.43 2002-3: +1.20 1969-70: +1.14 1982-3: +1.08 1960-1: +1.07 1963-4: +1.06 1986-7: +1.01 Note that all of these were El Niño except the ENSO neutral 1960-1. The highest PNA on record currently for La Niña is only +0.86 (2000-01). So, that will be obliterated. https://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/norm.pna.monthly.b5001.current.ascii.table

At NYC using Don’s projected 3.2 BN for Feb, it would rival the 2009-10 DJF average. But it doesn’t appear to me it would be quite as cold as 2014-5, 2013-4, and 2010-1 (using same base). @donsutherland1what do you think?

Barney says hi boys and girls on the 0Z UKMET 168 (7PM EST on Feb 18th: frigid N Rockies/Plains to upper Midwest with 2m anomalies -32 to -45) and it’s plunging south thanks to the extreme -AO/strong +PNA combo; temps <0F all day into NE/IA and dropping with lobe of TPV; near coldest of winter to date some of that area and it’s coming SE! https://www.pivotalweather.com/model.php?m=ukmo_global&p=sfct_anom-imp&rh=2025021200&fh=168&r=us_nc&dpdt=&mc= It is 12-48 hours after this that is the timeframe for the model consensus’ SE storm threat.

I think we’ll be tracking this for awhile am and currently thinking this has a good chance to be SE next significant threat. The progged extremely strong -AO just before along with solid +PNA gives me added confidence. 0Z EPS 10:1 snow:

0Z Euro: Similar position to GFS/CMC:

0Z GEFS mean (10:1) through Feb 21st