January 24-25: Miracle or Mirage

[MillvilleWx]

14 minutes ago, andyhb said:

And for the knockout punch...

PDII is probably my choice for a closer analog. The banana high, attacking moisture from the south of Gulf origin, and multiple wave ejections from the southwest. A coastal development mid to late storm cycle during the event…lots of similarities. 

I am not, in any way saying the result will be the same, btw. I am saying pattern evolution similarities are there and that bodes well for the Mid Atlantic. 

[nj2va]

WxBell skipped between 168 and 228 so this isn’t all from this first threat.  There’s enough spread here to give caution to these ginormous hits on the OP. I’ll take # 42 please.

[87storms]

9 minutes ago, SomeguyfromTakomaPark said:

AI Ensembles did tighten up the northern edge a bit, perhaps it lost some of the more northerly solutions.  But it did increase total qpf in dc.   

La Niña’s gonna La Niña. I’m hoping for 4-6” here. Gonna be a challenge in this pattern.

[Eskimo Joe]

Posting base snowfall output gif for some comparison.

 

 

[clskinsfan]

4 minutes ago, Bob Chill said:

Climo is climo. I can't buy the 12z euro for 1 simple reason. It would be one of the top 5 biggest storms in history down this way. Idk if this is the kind of setup for something that historic. Blizzard of 96 was 24" in Roanoke. Feb 2014 was close to 20". A 15-20" storm is quite rare. Imo, the DC area is more likely to get 15-20" than central and swva.  That said, my yard is in a pretty good spot and I'm pretty fired up over the potential. 

Its a good sign when the CAD is pushing way past you into NC. If that is right its going to take a while to scour out that much cold air. 

[Eskimo Joe]

WPC upping snowfall potential in the D5-D7 range. Their 18z update.

 

 

[yoda]

Afternoon AFD from LWX 

KEY MESSAGE 2...Potential continues for possibly significant winter
storm this weekend, followed by extremely cold conditions next
week.

A potent cold front pushes through the region late Thursday into
Friday, followed by a reinforcing Arctic front late Friday into
Saturday. This will lead to increasingly cold conditions each day
from Thursday through the entire weekend. Well below average
temperatures are forecast, especially by Sunday. In addition, some
upslope snow showers are possible with each front. Extremely cold
temperatures are becoming likely Sunday night into next week, with
lows in the single digits and wind chills at or below zero. Near-
record low temperatures are possible.

The latest 12Z guidance today continues to show the possibility of a
significant winter storm across our area this weekend. One noted
trend is that precip onset is a bit later, with the heaviest precip
over the area now occurring Saturday night through sometime Sunday
afternoon. Additionally, the probabilities for freezing rain have
dropped to almost zero, mainly due to the strong Arctic high to the
north ushering in very cold temps at the surface and aloft. As a
result, the NBM 48-hour probability for at least 6 inches of snow
are at 40-60pct, and around 20-30pct for 1 foot of snow. One big
thing to note is that there could be a sharp QPF gradient on the
north side of the system, with that sharp cutoff possibly setting up
somewhere over our area. This would result in lower snow totals
along the MD/PA border, with increasing totals to the south.

The upper-level pattern becomes quite active in both the northern
and southern branches of the jet stream. Models seem to be in at
least good agreement regarding the development of a low pressure
system that tracks across the southern U.S. A broad area of
baroclinic/frontogenetic forcing will develop along the interaction
of the Arctic high to the north and deepening low. Ensemble guidance
continues to show an amplified southern stream influence - something
we have seen very little of so far this winter (typical of La Nina).
The surface low may not escape as easily out to sea given the -NAO
block. The nearby steady source of very cold air and the amplified
southern stream occurring in tandem are what raise some red flags
for significant wintry precipitation potential this weekend.

Depending on where the frontal zone is and where the area of low
pressure tracks, there could be significant wintry precipitation
this weekend over a large part of the South to Mid-Atlantic CONUS.
The potential is still there for that strong Arctic high pressure to
suppress the low pressure system to our south. However, the
strengthening upstream blocking pattern could essentially put a
floor on how far south the low will track.

It is important to monitor this threat closely this week as the
different parts of the system become better sampled by surface and
upper air obs.

&&

[TowsonWeather]

8 minutes ago, WxUSAF said:

I don’t have @psuhoffman’s photographic memory for random 6z runs of failed storms, but my memory for late February last year was we had this amazing signal but guidance was never keying in on the same storm or shortwave? It was more of a several day period that looked good (and failed). So this looks quite different with a clear shortwave and storm development scenario. 

This is the most encouraging aspect of this to me: that the evolution of this system is much more straightforward and with fewer moving parts than is "typical" for a big MA snowstorm. Range of possible outcomes still on the table, but as these things go, the key pieces are clear. Figuring out the details of the southern energy ejection and when/if/how much it interacts with the northern stream will obviously tell the tale of where the biggest impact is, but we aren't counting so much on a precisely timed phase with a vort dropping in from western Canada - this is a long-track system with a surge of moisture into a cold antecedent airmass. 

[Eskimo Joe]

Big takeaway from the various 12z ensembles is that any overly amped solution that would lead to mixing or a changeover seems to have diminished.

[SnowenOutThere]

13 minutes ago, WxUSAF said:

I don’t have @psuhoffman’s photographic memory for random 6z runs of failed storms, but my memory for late February last year was we had this amazing signal but guidance was never keying in on the same storm or shortwave? It was more of a several day period that looked good (and failed). So this looks quite different with a clear shortwave and storm development scenario. 

From what I remember that was a concern that persisted for a bit but ultimately was solved by the time before the collapse. The main issue was that the PV went from acting as a cold source that sorta went live and let live with the storm to a crusher. You are right where the ens showed such an amazing signal for like 9 days out from the storm because of the whole period but it did consolidate before collapsing. I agree that this storm generally seems to be in a far better position. Only last thing I care about seeing before all systems go for a substantial (not hecs) storm is that all models drop the chance of not ejecting the SW

[Ji]

12z EPS has effectively shunted all the IP/ZR risk south of I-66/US 50. 

Never even considered that a risk

[SnowenOutThere]

I do think that today's 12z suite may have been the best possible outcome anyone could've hoped for if they want to see the odds of a major snowstorm increase. Every single model minus the GFS increased outcomes and generally decreased the odds of missing north or south. It's pretty rare to see something like that happen. 

[bncho]

https://x.com/AccuRayno/status/2013290491517743459

bernie rayno buys the euro AI the most, favoring nothern solutions, says there will be 15:1 ratios

[stormtracker]

47 minutes ago, TSSN+ said:

So ugh the big question, when does gfs fold? 

0z Sunday

[Eskimo Joe]

Trends have been great today, but still leaning in he @WxUSAF camp and weighing towards the ensembles until we get inside HR 84.

[understudyhero]

Would that be around Thursday's runs?

[snowfan]

10 minutes ago, bncho said:

https://x.com/AccuRayno/status/2013290491517743459

bernie rayno buys the euro AI the most, favoring nothern solutions, says there will be 15:1 ratios

There are a number of factors that can impact ratios. I'd hold off on that til closer to game time.

[MN Transplant]

5 minutes ago, Eskimo Joe said:

Trends have been great today, but still leaning in he @WxUSAF camp and weighing towards the ensembles until we get inside HR 84.

At least until we get convergence on the individual members. This is still a substantial spread on the GFS.  Still ~8 of 20 members that are duds for most of us.

 

[TSSN+]

Just now, MN Transplant said:

At least until we get convergence on the individual members. This is still a substantial spread on the GFS.  Still ~8 of 20 members that are duds for most of us.

 

Gefs is based on gfs which was a dud so not shocking most its ens aren’t great. 

[HighStakes]

1 hour ago, MillvilleWx said:

Just pointing out that this setup with post-storm temperatures <10° is very much a possibility with the HP anchored to the north. This is a prolonged cold spell incoming, regardless of snowfall. Snow will only exacerbate the cold potential due to refrigeration effects. 
 

If you are in a home that takes oil or fire wood, I would start preparing to have a delivery or go restock the firewood, pellet stoves for the incoming stretch of cold. It could last a while. 

Yes! 12Z Euro has northern MD dropping below 20 degrees Friday afternoon and not getting above 20 degrees until sometime the following Wednesday which is over 120 hours. We've had many strong shots of cold but many times they're in and out and rarely sustained. This appears to be different. 

[Eskimo Joe]

6 minutes ago, understudyhero said:

Would that be around Thursday's runs?

Yes 12z Thursday is my go/no suite for this event.

[SnowenOutThere]

Showtime

[Ephesians2]

"Snow likely" 5 days out is rare. 

[clskinsfan]

36 minutes ago, Ji said:

Never even considered that a risk

If it is wound up like some of the models say it will be. Then mix is definitely on the table. Always is for our area. 

[Eskimo Joe]

Unable to post here because I'm dumb, but 72-hr mean snowfall for NBM now has the 6" line up in southern PA. 10" line runs through DC.

[WVclimo]

Pretty good agreement

[MillvilleWx]

5 minutes ago, HighStakes said:

Yes! 12Z Euro has northern MD dropping below 20 degrees Friday afternoon and not getting above 20 degrees until sometime the following Wednesday which is over 120 hours. We've had many strong shots of cold but many times they're in and out and rarely sustained. This appears to be different. 

This arctic intrusion reminds me so much  of PDII with its alignment and positioning. I can still picture the 1040 HP on the WBAL Morning news that morning of the storm drilling cold air into the area with moisture attacking. It was 12° and snowing all day. Just surreal. This has the ability to deliver something like that…a cold smoke. 

[SnowenOutThere]

News of the weekend has broken containment as people are talking about it reaching below 0 with a foot of snow in convos I’ve passed by. Man the urge to correct them is strong. 

[MillvilleWx]

1 minute ago, WVclimo said:

Pretty good agreement

Great agreement and a ton of moisture for a smoothed mean. The heavier precip depiction back into the Lower Mississippi to Deep South is indicative of convection too. That’s another classic signature for here. 

[WxUSAF]

2 minutes ago, SnowenOutThere said:

News of the weekend has broken containment as people are talking about it reaching below 0 with a foot of snow in convos I’ve passed by. Man the urge to correct them is strong. 

If/when the GFS shows a MECS, that's when it will really break out because I think that's what the Apple weather app uses predominately?