Wintry December 28-29th Possible Winter Storm

[Webberweather53]

Man, the German model looks sweet. Hope the other models like GFS continue with the NW trend, but if the German is right, then who cares what the others show. Just wonder why we can't have an American model with better resolution like the German. Maybe the GFS replacement one will be better.

The GFS's replacement model (FV3) is suppressed atm, but not as much as the GFS. It seems NCEP has made some adjustments to the FV3 that have partially corrected the GFS's southeasterly bias esp in the short-medium range.

6z GFS


6z FV3



http://www.emc.ncep.noaa.gov/mmb/cguastini/fv3/fv3images.html

 

[BHS1975]

More like the ICON will be a legend haha!

You mean will be an “icon”


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[SimeonNC]

Sorry if this is banter but I'm beginning to think that this threat has more legs than the NYE one atm.

 

[BHS1975]

But this one reminds me of the 2014 event where it started pouring down snow and the radar blew up just from a little bit of overrunning.


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[Webberweather53]

Exactly. With a steep isentropic surface from a very strong CAD dome we just need a little nudge to get overrunning going. It's one reason I think these super high resolution models may be on to something, because they may be picking up on the magnitude of the overrunning where guidance like the GFS and CMC don't stand a chance until the precipitation is already developing.

The one thing that does worry me is that we're probably going to be hard pressed to get southwesterly flow over this low-level CAD dome & thus our mid-level winds will be more oblique relative to the nose of the CAD, which ultimately changes the response w/ this overrunning event... However, even if we get winds that are just a tick south of due west, we'll immediately start tapping into moisture left behind by the most recent CCKW over the tropical eastern Pacific instead of mostly out of the Gulf of Mexico, as we're often more accustomed to seeing. There's certainly a very large contribution of low-mid level moisture from both the tropical eastern Pacific and Gulf in this case...

 

[Metwannabe]

Apparently the UKMET is stronger with the low and the precip, according to someone at the other board.

It is an improvement, precip map only goes out to 72 that is much improved from the 0z run I believe.

 

[Webberweather53]

It is an improvement, precip map only goes out to 72 that is much improved from the 0z run I believe.

No net change vs the 0z run, but yes for a while there around 60-66 hours there was some improvement. I guess the big takeaway is the suppression trend is coming to a halt in most NWP (besides the low resolution GEFS)

 

[SimeonNC]

It is an improvement, precip map only goes out to 72 that is much improved from the 0z run I believe.

Trending towards the ICON, great!

 

[Metwannabe]

No net change vs the 0z run, but yes for a while there around 60-66 hours there was some improvement. I guess the big takeaway is the suppression trend is coming to a halt in most NWP (besides the low resolution GEFS)
View attachment 2333

I forget Ryan's site has Ukmet also... lol thanks

 

[Webberweather53]

I forget Ryan's site has Ukmet also... lol thanks

Sure thing! His UKMET precipitation maps usually come out exactly at 1230pm/am eastern

 

[deltadog03]

Interesting

 

[deltadog03]

Well figured NAM would be the wettest. But as y'all have noted, models are definitely a bit wetter for the 1st system

 

[Snowflowxxl]

What’s the Euro showing

 

[GaWx]

12Z Euro is similar to the 0Z Euro and remains dry for all but a small qpf near the se coast.

 

[deltadog03]

12Z Euro is similar to the 0Z Euro and remains dry for all but a small qpf near the se coast.

Well dang. NAM vs the world? Well and the icon lol

 

[Mitch West]

Was there any shift whatsoever with the euro either way?

 

[Mitch West]

Euro at H5 also looked a little better. We need just a little bit more of this trend. As Webber posted earlier, if we can just get winds aloft to tap that moist air to our south it will set off significant overrunning and precipitation will blossom nicely. As bad as it looks with precipitation, it could go from zero to something much bigger with only another tick or two in the same direction at H5.

00Z:

12z:

For whatever reason, I can't open these photos. So what is the most notable difference you saw between the two?

 

[Webberweather53]

Well dang. NAM vs the world? Well and the icon lol

And the 1km very high resolution Swiss model, but yea not too many models onboard just yet

 

[Mitch West]

The disturbance was a little stronger, a little more separate from the northern stream vortex and it was able to veer the flow nearly westerly compared to 00z. You could even see in the precipitation shield that it was closer to the coast (still offshore) than 00z. There was also a little more energy in the vorticity streamers feeding into the shortwave from the south.

Any good trend works even if it's small for now.

 

[GaWx]

Euro at H5 also looked a little better. We need just a little bit more of this trend. As Webber posted earlier, if we can just get winds aloft to tap that moist air to our south it will set off significant overrunning and precipitation will blossom nicely. As bad as it looks with precipitation, it could go from zero to something much bigger with only another tick or two in the same direction at H5.

00Z:

12z:

Yeah, A few years ago I researched the H5 maps for many SE sig qpf winter events that weren't clippers. The one thing that the vast majority of them had: WSW (at least a little S of W) or SW winds at H5 over one's location. VERY few had straight W winds and almost none had WNW winds at the locations of the sig winter event. Again, I'm not talking about light precip events or clippers.