GaWx

12Z GEFS big picture in more ways than one: classic split flow has been showing for this period for weeks. This is about as good a look as I’ve seen in recent years this far out. Ingredients are there. But will they mix right? That’s always the tough part for the SE, especially.

12Z GEFS for Feb 16 is by a good margin coldest in at least the last 16 runs. Now let's see how well the ST jet/moisture interacts.

GLAAM prediction from CFS ensemble is saying we’re probably headed to solid +/Nino pattern 2/15+.

The potential isn’t going away folks. Rather, it is persisting and as we get closer it is increasing. The potential on the 6Z GEFS for widespread significant wintry precip during a portion of Feb 15-20 in NC and more specifically from a classic Miller A GOM originating low throughout a large portion of the SE during a portion of Feb 17-20 is about as high as I can remember on any GEFS in recent years when looking out 11-16 days. When I consider not only the actual panels of the run but also similar model runs of the last few days along with the progged solid +PNA/-EPO/-AO, neutral to -NAO, a persistent 50/50 low, a strong El Niño related subtropical jet/split flow, and moderate+ Nino mid to late Feb climo, it is hard to hold in my enthusiasm for what MAY occur. And it is always a matter of what MAY and never nowhere near what WILL when looking out 11-16 days. The MAY is why we have these forecast discussion threads as opposed to nonexistent crystal ball threads. Classic split flow: Many members with Miller A GOM/off SE coast lows:

If the extended 2/3 10 mb forecast along with the most recent CFS 12 run ensemble 2m temperature means in addition to recent Euro Weeklies are any indication of what’s to come, we may very well be getting a cold first half of March at a bare minimum! The mean 10 mb wind never recovers over +7 after not getting below +30 in mid to late Feb on the Jan 25 run!! That 1/25 run had a mere 3% chance for a Feb reversal and now it is 75%+! I’ll delete this image very soon as it is way too large to keep here considering the attachment limits:

About 30% of the 18Z GEFS members have wintry precip in the SE outside of the mountains during 2/17-19.

Meanwhile, though the 12Z EPS has virtually no snow, the 0Z control has moderate snow 2/18 and 3/2-3.

This is about as good as it gets per his monthlies and getting the unrounded peak exactly and thus I think should be the winner! However, he messed up his perfection by “not playing by the rules” (as he stated) since his definition of super is 2.0+, not >2.0 (with which I agree). Thus he voted >2.0 even though he predicted +1.97 unrounded/+2.0 rounded. I still say he wins. Congrats!

That he did. So, congrats @snowman19for that! This one is just like 1965-6, which peaked at +1.98. That one is often left out of the “super” peaking group even though it also rounded to 2.0. Not that it matters wx wise. Edit: for wx though, RONI may matter more.

The unrounded ONI max came in at +1.97. RONI never made strong with another +1.49.

EPS: ~25% of members have strong cold within 2/17-18 but snow is very limited (though it ends a day earlier than GEFS).

12Z GEFS: pretty wet SE 2/18-9 with 9 of 31 members having wintry precip. Many members have a GOM low.

12Z GEFS is warmer 2/15 than any recent run.

The 2/3 models (image below) are even more bullish for a major SSW with the GFS’ 2/16 reversal plunging way down to -17 and still dropping at the end (likely overdone)! GEFS mean now drops to -2 and still dropping at the end. Including the GFS, 6 members drop below -10 with a couple more possible after the end. GEFS extended means for mid to late Feb -1/25 run: stayed over +30 -1/29 run: stayed over +20 -1/30 run: stayed over +15 -1/31 & 2/1 runs: stayed over +10 -2/2 run: stayed over +7 -2/3 run: dipped to -2 and still dropping into extended, which hasn’t been released yet Meanwhile, CFS forecasts for the 1st half of Mar in the E US have gotten much colder.

-The mean calendar day snowfall is highest for 1/19, 1/25, 2/9, 2/26, and 3/2 with 3/2 the peak. -The highest mean 7 day periods are 1/24-30 and 2/26-3/3 with 2/26-3/3 THE peak. -There’s no telling how cold the SE will get. It is still too far out to have high confidence in and ensemble means are not going to show the degree of cold well due to timing differences of members causing a smoothing of the mean. But some of the projections I’ve seen are quite cold for that far out on a mean of an ensemble. Plus the cold is being forecasted to be strongest anomalywise in the E US rather than the mid Jan central US. -The Euro Weeklies severely underestimated the degree of mid Jan cold with them actually having warm anomalies throughout the US just over 2 weeks out! Even the map issued on 1/15 for 1/15-1/21 was quite a bit underdone. -Moderate+ El Nino climo favors 2/15+ for the best period for snowfall, even moreso for the 9 that had none in Dec and Jan. Those 9 averaged over 5” just for 2/15+. https://www.weather.gov/wrh/Climate?wfo=rah

Thanks for posting this. The dashed red line that doesn’t come back up to the ERA5 mean until late March is from 2023 and isn’t the GEFS forecast. GEFS is all in green and ends on Feb 18. One member plunges to -20. It appears that ~30% go <0 by Feb 18, a significant increase vs recent runs. Trends have clearly been going toward a major SSW over the last few days. The earliest reverse is Feb 15. The mean likely gets down to ~+4.

Groundhog weeklies say spring may be awhile: mean dips to +11 with ~15 reversals at midmonth. A week ago the 1/26 run had only 3 midmonth reversals with the mean dipping only to +31!

1. Tiger, also, 1964 was good and 1958 was great. 2. Come to papa (from 12Z GEFS)(GEPS similar) as at a minimum the ducks are on the pond. Look at all of the lows (red) in the Gulf: Along with a cold SE helped by -AO: Check out the split flow along with 50/50 low (helps hold cold in longer) just off the NE corner of the image: And if the period just after this doesn’t workout, the new Euro Weeklies are suggesting within the following week for an opportunity.

Per the latest model consensus, there’s a very good chance that the PNA for the 2nd half of Feb (2/15-29) will average +0.5+ and the AO will average sub -1. The following El Niño 2nd half of Febs met both of those conditions: 1988, 1983, 1978, 1977, 1970, 1964, 1958 So, during 1957-1988, 7 of the 13 El Niños met both of these. But interestingly the subsequent 10 didn’t. So, 2024 would be the first of the last 11. How did those 7 last half of Febs play out at NYC in terms of temperature anomaly and snowfall? 1988: 0/0.6” 1983: +4/0.0” 1978: -8/1.1” 1977: -1/1.9” 1970: -5/2.3” 1964: -6/10.6” 1958: -9/8.4” AVG: -4/3.6” So, temps were MBN twice, BN twice, NN twice, and AN once. Snowfall was MAN twice, BN three times, and MBN twice. The average was BN for temperatures and NN for snowfall.

Per the latest model consensus, there’s a very good chance that the PNA for the 2nd half of Feb (2/15-29) will average +0.5+ and the AO will average sub -1. The following El Niño 2nd half of Febs met both of those conditions: 1988, 1983, 1978, 1977, 1970, 1964, 1958 So, during 1957-1988, 7 of the 13 El Niños met both of these. But interestingly the subsequent 10 didn’t. So, 2024 would be the first of the last 11. How did those 7 last half of Febs play out at RDU in terms of temperature anomaly and snowfall? 1988: -3/0.0” 1983: -3/0.4” 1978: -11/5.6” 1977: -3/1.5” 1970: -7/T 1964: -9/2.0” 1958: -9/3.0” AVG: -6/1.8” So, temps were BN 4 times and MBN 3 times. Snowfall was AN for all 3 MBN temperatures and BN for 3 of the 4 BN temperatures. The average was BN for temperatures and AN for snowfall.

If the 6Z GFS 10 mb were to verify closely, that would result in a mid-month solid reversal/major SSW. There’d probably be significant implications for as early as very late Feb and continuing through much of March in the E US based on the past. In other words, the chances of a very late spring would be increased. The 6Z has the reversal start Feb 15-16. @Stormchaserchuck1: How long is the average lag from a mid Feb major SSW to the start of potential significant sensible E US wx effects? 6Z GFS at 10 mb hour 360 (for 6Z on Feb 17) has a net E wind at 60N:

If the 6Z GFS 10 mb were to verify closely, that would result in a mid-month solid reversal/major SSW. There’d probably be significant implications for very late Feb into March in the E US based on the past. In other words, the chances of a very late spring would be increased.

Now that we’re finally up to the cold part of Raindance’s forecast, it’s time to root for it to be right.

No, I mean that 3.3” fell 2/15-16/1930. That left behind snowcover of 3” on 2/16. It dropped to 2” snowcover on 2/17.

No, I meant 3” on the first day that had a 7 and 2” on the 2nd day of a 7.