• 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 Fail or Fab February 2023 Pattern Thread

Rain Cold said:
Anyone notice how we have pretty good runs at 12z but all the overnight stuff sucks?
Click to expand...
Ha ha.. yeah, I'll wake up at night to disappointment, then have the 6z bring something back, then have the 12z show some real promise, which then leads into 18z happy hour.
 
Myfrotho704_ said:
Many gonna have to realize this isn’t a great setup for snow, but rather for sleet/ice. I think I’m down bad to the point where I’d take anything however and be happy
Click to expand...
Yeah with SER flexing it’s going to be really hard to get snow… maybe we get lucky and get a strong FGEN band to set up a front end thump, but other than that the big hope would be to keep 925s cold enough to favor more sleet
 
rburrel2 said:
Hopefully the euro and EPS jump on board today, because they were really bad last night with respect to getting a storm/precip. I'm optimistic b/c it seems most models have trended trended better since then but who knows.
Click to expand...

These 50-50 lows are so fickle this far out.

Over the years, I’ve noticed models have a habit of being too progressive with big 50-50s like this & it’s one reason why CAD events usually trend better inside the medium range (day 5-7 ish & in)
 
This has the makings of a pretty significant event. Stronger subtropical ridge, the airmass over Southeast Canada is the coldest in the northern hemisphere. Mixing airmasses like that screams precipitation and especially if we can trend our energy stronger and further south as it comes across the plains. If we can get a 1040+ and honestly seeing the GFS spitting out 1050 HP and the CMC have a 1044 the idea of at least a 1040 isn't out of the question. Even in a progressive flow, a deepening 50/50 low will slow things down enough and having that strong of a HP sitting over that type of cold will lock in some pretty cold low level temperatures even with a Sliding east HP. Don't forget that the precipitation also locks in CAD as well. It will be interesting to see if we can get some FGEN driven front end snow as well.
 
iGRXY said:
This has the makings of a pretty significant event. Stronger subtropical ridge, the airmass over Southeast Canada is the coldest in the northern hemisphere. Mixing airmasses like that screams precipitation and especially if we can trend our energy stronger and further south as it comes across the plains. If we can get a 1040+ and honestly seeing the GFS spitting out 1050 HP and the CMC have a 1044 the idea of at least a 1040 isn't out of the question. Even in a progressive flow, a deepening 50/50 low will slow things down enough and having that strong of a HP sitting over that type of cold will lock in some pretty cold low level temperatures even with a Sliding east HP. Don't forget that the precipitation also locks in CAD as well. It will be interesting to see if we can get some FGEN driven front end snow as well.
Click to expand...
Let’s pump the breaks a bit before we start talking about FGEN snow lol.. let’s just see if we can keep the storm signal .. we may have cold but it’s still a delicate balance between perfect amount of cold and storm placement and storm strength .. this could easily be onset ice to rain deal let’s take it one step at a time
 
In a broader sense... seems like most of the models have our wetbulb temps around 23-25 Sunday morning thanks to the dry air blast from the wedge/CAD high. As such, even if/when we see the parent high move off the coast... you'd be looking at freezing rain lasting quite a while as we slowly warm from 23-25 to 32 with latent heat release. I don't see any mechanism to scour the remnant wedge so I think we would be in one of those latent heat release warming to end ice situations as it stands.

TLDR, if we actually get steady precip starting Sunday morning, the insitu wedge conditions look to be cold/dry enough for significant ice accretions before warming to freezing. imo (assuming the models/ensembles are right on the CAD strength and cold air transport Saturday).
 
1675566000-OGTWnuR2JzE.png

1675566000-wtybZxpfBXY.png

The airmass is so cold we are already well below freezing before the first drop of precip reaches us. Also the first clue of a really good deep cold airmass for CAD is when you have single digit dews on the Va/NC border. That has to happen
 
NickyBGuarantee said:
Let’s pump the breaks a bit before we start talking about FGEN snow lol.. let’s just see if we can keep the storm signal .. we may have cold but it’s still a delicate balance between perfect amount of cold and storm placement and storm strength .. this could easily be onset ice to rain deal let’s take it one step at a time
Click to expand...
Nobody is talking about this being a done deal lol. Simply pointing out that tends to be a typical process of overrunning especially with airmasses this cold and WAA being forced over it.
 
I'm a little worried about relying on the isentropic upglide over a wedge as the main driver of precip Sunday morning. I mean it's certainly possible, but we had a recent wedge event where that was forecasted and wound up never materializing(maybe 2019 or 2020). We were forecasted to get roughly .1-.2 liquid from the upglide before a front pushed through and most places wound up getting either nothing and a trace... when the main front came through 8-10 hours later we had finally warmed to around 32 and that fell as just rain as expected.

Every setup is different though and this one could work out well.
 
Last edited:
rburrel2 said:
I'm a little worried about relying on the isentropic upglide as the main driver of precip Sunday morning. I mean it's certainly possible, but we had a recent wedge event where that was forecasted and wound up never materializing(maybe 2019 or 2020). We were forecasted to get roughly .1-.2 liquid from the upglide before a front pushed through and most places wound up getting either nothing and a trace... when the main front came through 8-10 hours later we had finally warmed to around 32 and that fell as just rain as expected.

Every setup is different though and this one could work out well.
Click to expand...
We will need a strong and deepening wave as it comes into the southeast. The CMC showed this. Once you get that you won't have any issues getting isentropic upglide and forcing. Right now the Cold air isn't the issue. We are going to have exceptionally cold air to our north and a H5 pattern that supports CAD. It's really just a matter of getting the energy to dig far enough south and be strong enough to not get squashed by the TPV sliding east.
 
iGRXY said:
1675641600-NHV298IiyBM.png

By the time the wave makes it to the southeast, our High is about 1000 miles due east of Newfoundland lol
Click to expand...
It may very well be right, but is it just me or has the Euro become the model with more of a progressive bias. You used to never see it move features faster than the GFS
 
I'm having a hard time buying the progressive solutions w/ the 50-50 low.

It's a tough sell for me knowing a persistent, shallow, and unusually intense cold air mass sitting east of the Appalachians will tug on/slow down the +PVa aloft more than forecast by NWP (through generation of low-mid level static stability above the CAD dome >> +PV )

Here's the graphic I made ~ 5 weeks ago to explain how this physical process works:





If we had -NAO over the top, the easterly flow under the ridge would slow this trough down even further, but beggars can't be choosers.
 
Last edited:
1675641600-YC2CY12vNVs.png

EPS is similar to the OP in lifting the 50/50 out fast. Like Webber said, deepening 50/50 lows slow the progression of the pattern so I am a little skeptical myself. (Those big fantasy runs we had this month was typically due to a deepening 50/50 low that slowed the progression of the N/S). A -NAO would put the 50/50 in neutral. RIght now the EURO and EPS have this thing going 70 mph. A deepening 50/50 with no -NAO will be more like slowing up to 40mph, which is really all we need right now. The trailing wave is only about a day too slow right now which is nothing at this range.
 
Nomanslandva said:
Yea, looks like white rain to me, but it would be the best we've had, so... Im behind and getting caught up and with 4 pages this afternoon, there must be some more excitement ahead.
Click to expand...
Definitely hoping for a slight win with this
 
Webberweather53 said:
I'm having a hard time buying the progressive solutions w/ the 50-50 low.

It's a tough sell for me knowing a persistent, shallow, and unusually intense cold air mass sitting east of the Appalachians will tug on/slow down the +PVa aloft more than forecast by NWP (through generation of low-mid level static stability above the CAD dome >> +PV )

Here's the graphic I made ~ 5 weeks ago to explain how this physical process works:





If we had -NAO over the top, the easterly flow under the ridge would slow this trough down even further, but beggars can't be choosers.
Click to expand...

I seem to remember that around 5-7 days before last years storm on 1/16, the models… I think the Euro and UK especially were trying to move the 50/50 low out to fast. It would make sense that it should slow down and every thing behind if it’s deepening as much as modeled. Your right though that it’s shame we couldn’t get one in place a few weeks back when we had a strong negative NAO
 
Yeah, that's a sleet sign. How stagnant is it though or is it retreating quickly.
 
Big difference vs the failed 50/50 from jan, was the fact that in that January head fake storm, it was driven off a random piece of energy diving down around Atlantic Canada in a fast progressive pattern, that was limited on cold. this Time we already have tons of cold on top, and a big TPV, but pattern is still somewhat progressive. But a big wound up TPV is harder to move Vs a random piece of N/S energy. H5 imo is better this time.
 
Mitch West said:
View attachment 131744
Yeh that's pretty bad.
Click to expand...

This well known weak subtropical ridge bias in the GFS (which also shows up in the hurricane season and is probably related to the model’s CP scheme) is another reason why I didn’t like this event several days ago. Hopefully a few folks find a way to get some sleet or snow at the onset
 
1675414800-ZHPtWQaNErw.png

1675436400-cd1Gs15Y2MY.png

Stronger TPV and one that is further south. Also looks like the 2nd system is coming in faster out of the northwest. That stronger TPV should continue to help slow the progression if this continues in future runs.
 
iGRXY said:
gfs-deterministic-namer-mslp-1675015200-1675425600-1675555200-20.gif

You can see the 50/50 deepening and slowing way down. That's the type of trend you want to see as it will quickly slow our HP way down. And folks that sucker is legit. basically another 1050.
Click to expand...
Where’s the precip going to come from? Everything looks anemic at the times we are cold enough.
 
You must log in or register to reply here.
Back
Top