March 20-21 Potential - STORM MODE THREAD

[Amped]

Getting the 50/50 low out of the way was key on the 18z run.  Once that happened everything pivoted west, instead of east.

[T. August]

This is a serious question - why is the sim radar so broken on the 3k NAM? Does the hires screw those features up long range?

[high risk]

      The NAM3 looks way more reasonable, with the low moving off to the northeast at hour 60 (and not reforming by southern VA like the parent NAM).    The sleet is transitioning to heavy snow across our area at this time.    This is clearly taking longer to go from a sleet mess to snow that some other guidance, but the warm layers responsible for the prolonged sleet are just barely above 0 during the late overnight Tuesday, so it wouldn't take much to make it a bigger snow event.     It also has the idea of heavier precip struggling to get up into northern MD, although it's not as bad with that as the NAM parent.

[Bob Chill]

9 minutes ago, 87storms said:

If the blocking is that strong you’d think we’d avoid sleet.

Gotta break the back on cyclonic flow over Kentucky or the mids stay hostile. Nams didn't want to cool the column as wave 1 goes off the coast because of that. The second wave does the job but before that it's messy. 

[Interstate]

5 minutes ago, yoda said:

I think we can work with that closed h5 position at 60 on the 3k

So I am guessing that after hour 60, we can assume that blob of snow moves east to the rest of the subform?

[psuhoffman]

Nam=ugh

988 low just off the coast and yet nothing but spotty precip most of the time then develops a ccb that's all of 20 miles wide. That would be an epic fail and lol. 

I think part of the problem is it went weak and disjointed with wave 1 again letting that escape then we're back to fighting to get good moisture transport and closed circulation with the next wave. Just when we thought everything was going more consolidated. Hopefully it's just the nam being the nam. 

[87storms]

Looks like the h5 low was further south this run. Almost looks like it slides slightly Southeast through Virginia. 18z kept the closed low just under us. 

[yoda]

Just now, Interstate said:

So I am guessing that after hour 60, we can assume that blob of snow moves east to the rest of the subform?

I hope so... perhaps others like @high risk or @Bob Chill can answer better

[ldub23]

1 minute ago, psuhoffman said:

Nam=ugh

988 low just off the coast and yet nothing but spotty precip most of the time then develops a ccb that's all of 20 miles wide. That would be an epic fail and lol. 

I think part of the problem is it went weak and disjointed with wave 1 again letting that escape then we're back to fighting to get good moisture transport and closed circulation with the next wave. Just when we thought everything was going more consolidated. Hopefully it's just the nam being the nam. 

Spotty and i would think prone to the precip drying  up rather fast. It is much more realistic here however.

[poolz1]

Yea...3k is a much more realistic evolution.  Has a very classic look to the radar....precip moves in from the SW and by the end of the run echoes are moving E --> W.

 

[Bob Chill]

1 minute ago, Interstate said:

So I am guessing that after hour 60, we can assume that blob of snow moves east to the rest of the subform?

Yes, look at the 850 frontogenesis panel at 60. That area just west of dc is going to move through as the low pulls away. That would likely be a band of heavy snow. 

[Maestrobjwa]

8 minutes ago, BTRWx's Thanks Giving said:

Boom!

I find the hole over @psuhoffman's house to be hilarious, hahaha

[high risk]

2 minutes ago, yoda said:

I hope so... perhaps others like @high risk or @Bob Chill can answer better

      I think so.    If you step through the 850 wind panel on TT,  it looks like the CCB is aimed right at us at f60 and may be about to pivot.   It also looks like a new 850 circulation is trying to form down by southeast VA, though, and that kind of messed things up for us between f60 and f84 on the parent NAM.

[Bob Chill]

I'm done parsing the nams late in their runs but the 3k has an 850 low right at the mouth of the bay with upper level support moving through. Thats a heavy snow signal. Especially in march. 

[87storms]

Yea the 3km looks like it would be a more easterly component to that upper low. Probably a better precip shield.

[high risk]

3 minutes ago, Bob Chill said:

Yes, look at the 850 frontogenesis panel at 60. That area just west of dc is going to move through as the low pulls away. That would likely be a band of heavy snow. 

 

       Bob, the only concern, though, is that you can see an 850 circulation forming down east of ORF.     It's hard to say with will come of that feature, and the f60 NAM3 doesn't quite match the f60 NAM12, but the NAM12 developed an 850 low down there too and that screwed things up after f60....

 

[87storms]

1 minute ago, Bob Chill said:

I'm done parsing the nams late in their runs but the 3k has an 850 low right at the mouth of the bay with upper level support moving through. Thats a heavy snow signal. Especially in march. 

3km looks damn near perfect lol

[BTRWx's Thanks Giving]

2 minutes ago, high risk said:

 

       Bob, the only concern, though, is that you can see an 850 circulation forming down east of ORF.     It's hard to say with will come of that feature, and the f60 NAM3 doesn't quite match the f60 NAM12, but the NAM12 developed an 850 low down there too and that screwed things up after f60....

 

Why would a deepening low lose its juice like that?

[Ralph Wiggum]

Hopefully it's just the nam being the nam. 

My gut feel is this statement is right. The NAM doesn't have a whole heck of alot of support at all for what is just vomited up.

[Bob Chill]

1 minute ago, high risk said:

 

       Bob, the only concern, though, is that you can see an 850 circulation forming down east of ORF.     It's hard to say with will come of that feature, and the f60 NAM3 doesn't quite match the f60 NAM12, but the NAM12 developed an 850 low down there too and that screwed things up after f60....

 

I think what the nams are telling us is wave 2 is legit. Both close off h5 and roll it through to our south. That plus the 850 low position and trajectory tells me that the upside that the 12z euro showed for wave 2 may be better than we think. It's touchy and it's not going to be an expansive shield but we're probably in an ok spot. 

I've never once in all my tracking years seen what the nam12 did at the surface compared to the upper levels. I guess it's possible but I have no issues tossing it either. 

[MillvilleWx]

11 minutes ago, Interstate said:

So I am guessing that after hour 60, we can assume that blob of snow moves east to the rest of the subform?

 

8 minutes ago, Bob Chill said:

Yes, look at the 850 frontogenesis panel at 60. That area just west of dc is going to move through as the low pulls away. That would likely be a band of heavy snow. 

 

To piggy back what bob was deciphering using H85 frontogen, you can take a look at H7 and notice there's a nice cyclonic flow pattern to the south over VA, likely the closed H7 low, which is actually in a prime spot for divergence within the area shaded on the northern side of the low (H7 plot). There would be a band of heavy snow that pivots across the region and would be fairly decent in the ratio department (~ 10:1 in that setup) as better lift across the low-mid levels (Sounding). DGZ is still not prime, so not a fluff bomb by any means, but solid for accumulation within the banding. 

 

[psuhoffman]

3k looks pretty awful up here too. Both are south with the WAA wave then have a dryslot here with  wave 2. 

[high risk]

2 minutes ago, BTRWx's Thanks Giving said:

Why would a deepening low lose its juice like that?

     

1 minute ago, Bob Chill said:

I think what the nams are telling us is wave 2 is legit. Both close off h5 and roll it through to our south. That plus the 850 low position and trajectory tells me that the upside that the 12z euro showed for wave 2 may be better than we think. It's touchy and it's not going to be an expansive shield but we're probably in an ok spot. 

I've never once in all my tracking years seen what the nam12 did at the surface compared to the upper levels. I guess it's possible but I have no issues tossing it either. 

   

    Instead of maintaining a nice deep, closed 850 low, it basically turned into more of an 850 elongated low extending off to the northeast.    But Bob is trying to tell me nicely that I'm probably wasting too much time parsing details of a wacky run, and I agree that there is a lot of positive to take away from the NAM runs, especially the 3k.

     

  

[Bob Chill]

1 minute ago, psuhoffman said:

3k looks pretty awful up here too. Both are south with the WAA wave then have a dryslot here with  wave 2. 

Might wanna run to Ulta and buy some fake nails. 

[Bob Chill]

3 minutes ago, high risk said:

     

   

    Instead of maintaining a nice deep, closed 850 low, it basically turned into more of an 850 elongated low extending off to the northeast.    But Bob is trying to tell me nicely that I'm probably wasting too much time parsing details of a wacky run, and I agree that there is a lot of positive to take away from the NAM runs, especially the 3k.

     

  

Don't get me wrong....a fail is always on the table until I'm done shoveling and the sun is out. The gfs will probably come in juiced all the way into southern pa with lots of rain in my yard before a flip while Psu builds snowmen with his son. 

[yoda]

H5 at 42 on 00z RGEM has s/w in the northern Gulf lol

[psuhoffman]

Rgem has a dryslot over north central md too

[AfewUniversesBelowNormal]

GFS should come north

[Interstate]

2 minutes ago, psuhoffman said:

Rgem has a dryslot over north central md too

Yeah... but isn't that mostly because it is between waves?  You can see it coming

[ohwxguy]

00z RGEM meteogram seems to indicate the 2nd wave could produce a nice period of snow on Wednesday after a lull in precip later Tuesday into the overnight hours.  Prior to that, mostly rain with some mix.