December Med/Long Range Discussion

[showmethesnow]

9 minutes ago, Windman18 said:

12z Para GFS looked pretty sweet. Snow to rain back to heavy snow. Gives the area 8-12" it looks like.

Close with the Wed Night/Thur storm as well. 

[stormtracker]

4 minutes ago, Ji said:

Best gfs run since hecs of Jan 2016

Definitely the O face model.   The regular GFS is Valley Low model.  

[midatlanticweather]

And... If it were not for the para I would have already said... 

 

Next. 

 

But I am kind of saying that! Trends are bad. 

[BristowWx]

If I may ask what is the para?  I mean in relation to the GFS.  I know what it is supposed to be but is it a trustworthy source.  I hardly see it mentioned except in the context of the NAVGEM or JMA.  I would love to worship it right now.

[showmethesnow]

1 minute ago, losetoa6 said:

Looks like next Sunday will have to be watched for maby left over energy from Saturdays cutter running into reinforcing cold air. Many of the gefs members show this posibility.

The possibility has been popping up here and there on the OPs, and their ensembles for the last couple of days. One way to score in this type of pattern with energy running up a trailing cold front.

[showmethesnow]

5 minutes ago, losetoa6 said:

I personally am not going to sweat precip types and amounts for Saturdays system until the short range -72 hours. We are what...135 hours out. We've seen time and time again the models scouring cad out to quickly. If Thursday /Friday verify teens and low 20 highs that's some real anomalous cold . My bet is we are far from the final outcome with this system and I look forward to the tracking .

Most cases the CAD holds on longer but I have seen it get scoured out so quickly it was like someone flipped a switch. Not saying that is the case here though but I wouldn't discount it. 

[Scraff]

9 minutes ago, losetoa6 said:

I personally am not going to sweat precip types and amounts for Saturdays system until the short range -72 hours. We are what...135 hours out. We've seen time and time again the models scouring cad out to quickly. If Thursday /Friday verify teens and low 20 highs that's some real anomalous cold . My bet is we are far from the final outcome with this system and I look forward to the tracking .

Yes. This. Things are likely going to change quite a bit over the next few days. Fun to watch all the models come out, but no need to start a winter sucks thread. Save that for January! Lol. 

[Bob Chill]

Eps very supportive of 2-4 through the region overnight Friday. Mean for my yard is about 3.4". The good part is the mean isn't skewed by a bug cluster. Pretty uniform for the lead.  

There is also support for a trailing system but no strong signal. It's def there though. Mean for my yard is around 2" but a couple big hits skew that. All in all is was a decent run. 

[Maestrobjwa]

10 minutes ago, losetoa6 said:

I agree. ..it has tuck taled and run occasionally but it helps to have low 20 highs versus ..say low 30 highs with the retreat starting. Also being 5/6 days out the big players could still shuffle a bit.

And for the last two winters, I remember 2 or 3 times when the cold air mass was so strong that the models (at least in the LR, anyway underestimated how long it would take to erode! So it sounds like...the colder Thurs. and Fri. are, the more we may have to watch this one...

[Maestrobjwa]

2 minutes ago, Bob Chill said:

Eps very supportive of 2-4 through the region overnight Friday. Mean for my yard is about 3.4". The good part is the mean isn't skewed by a bug cluster. Pretty uniform for the lead.  

There is also support for a trailing system but no strong signal. It's def there though. Mean for my yard is around 2" but a couple big hits skew that. All in all is was a decent run. 

So we're still looking at a storm that goes from Friday to Sunday, with major questions about precip. type during the day hours on Saturday?

[showmethesnow]

11 minutes ago, Maestrobjwa said:

And for the last two winters, I remember 2 or 3 times when the cold air mass was so strong that the models (at least in the LR, anyway underestimated how long it would take to erode! So it sounds like...the colder Thurs. and Fri. are, the more we may have to watch this one...

Another important aspect and probably more so, is the depth of the cold on the surface. THe deeper that is the harder it is to drive the cold out. But on the other hand a very shallow layer on the surface can get scoured out very quickly no matter how cold it is on the surface.

[eurojosh]

Bit of a jump there on the 18z GFS at 144 vs 150 on the 12z.  LP is much further south - but unfortunately so is the HP off the coast...

[Bob Chill]

Pretty major shift at h5 leading in. Low is slower so that sucks but instead of strong ridging in front of the vort, there is actually confluence. That + faster with the shortwave = decent event. 

[showmethesnow]

2 minutes ago, Bob Chill said:

Pretty major shift at h5 leading in. Low is slower so that sucks but instead of strong ridging in front of the vort, there is actually confluence. That + faster with the shortwave = decent event. 

1029 High over top of the low instead of behind it as well at least until hour 138.

[stormtracker]

2 minutes ago, Bob Chill said:

Pretty major shift at h5 leading in. Low is slower so that sucks but instead of strong ridging in front of the vort, there is actually confluence. That + faster with the shortwave = decent event. 

If it aint one thing, it's another.  The low is getting to where we want it, but slower.  

[Wonderdog]

Why hasn't anyone talked up the CMC. It continues to show snow to frozen or mix  next weekend? Seems colder longer than the other models.

[Bob Chill]

Just now, stormtracker said:

If it aint one thing, it's another.  The low is getting to where we want it, but slower.  

Who knows what this will look like in 2-3 days. Or what transpires after the front clears. The angle of the boundary being more w-e instead of n-s can make things interesting at least. 

[showmethesnow]

Surface is definitely different. Would not be surprised if this run pops a low down south that runs up the trailing cold front.

[WinterWxLuvr]

Just slight changes to the gfs  

[nflwxman]

6 minutes ago, Bob Chill said:

Who knows what this will look like in 2-3 days. Or what transpires after the front clears. The angle of the boundary being more w-e instead of n-s can make things interesting at least. 

One can certainly see the potential if the low ejects from the Rockies as fast as the para shows it with the orientation of the GFS.  Unfortunately, the high moving out is a feature of nearly every model and ensemble, which would make a heavy snow event highly unlikely.  Still way to far out to even begin to consider what the precip shield with this will look like and/or if a big front end is on the table.

[Wonderdog]

2 minutes ago, nflwxman said:

One can certainly see the potential if the low ejects from the Rockies as fast as the para shows it with the orientation of the GFS.  Unfortunately, the high moving out is a feature of nearly every model and ensemble, which would make a heavy snow event highly unlikely.  Still way to far out to even begin to consider what the precip shield with this will look like.

Wouldn't that big ass LP in Canada funnel more cold air into our region with its counter-clockwise rotation

[Bob Chill]

1 minute ago, nflwxman said:

One can certainly see the potential if the low ejects from the Rockies as fast as the para shows it with the orientation of the GFS.  Unfortunately, the high moving out is a feature of nearly every model and ensemble, which would make a heavy snow event highly unlikely.  Still way to far out to even begin to consider what the precip shield with this will look like.

I doubt many are thinking heavy snow event. The 12z euro yesterday was max potential and unlikely. We've had plenty of similar type of events in the past. Usually a burst of snow that can over perform sometimes but usually in the 1-5" range tops followed by a flip and countdown to a drip fest. Flips usually happen earlier than we want and the drip fest Usually starts later than forecast. That actually sounds like a good forecast. I'll go with that for now. Lol

[nflwxman]

2 minutes ago, Wonderdog said:

Wouldn't that big ass LP in Canada funnel more cold air into our region with its counter-clockwise rotation

It's probably too far to have an impact.  If anything it's a negative since it clears the way for our sensible wx low to move northward.

[Bob Chill]

5 minutes ago, Wonderdog said:

Wouldn't that big ass LP in Canada funnel more cold air into our region with its counter-clockwise rotation

No, the hp that slides off the coast pumps southerly flow aided by the approaching low from the west. The gfs has been consistent with terrible hp placement off the east coast. 

[WinterWxLuvr]

When I see a change this big it makes me think anything is possible.  The h5 change is pretty big for a 6 hour model difference.

[showmethesnow]

Major changes on the surface and 500's that really scramble the picture especially  in the longer ranges. So are we talking the model starting to see changes or do we toss this run out? 

[nflwxman]

2 minutes ago, Bob Chill said:

I doubt many are thinking heavy snow event. The 12z euro yesterday was max potential and unlikely. We've had plenty of similar type of events in the past. Usually a burst of snow that can over perform sometimes but usually in the 1-5" range tops followed by a flip and countdown to a drip fest. Flips usually happen earlier than we want and the drip fest Usually starts later than forecast. That actually sounds like a good forecast. I'll go with that for now. Lol

Yeah, seems reasonable at this range haha.  I just don't really buy we are really in the range to understand local impacts with any granularity.  The consensus for a big storm in the plains with cold air in place on the EC.  That's why I'm not punting until Tuesday at the earliest.  It's the frontal storms that have cold air rushing into the area that I'm usually more skeptical of.

[Maestrobjwa]

4 minutes ago, WinterWxLuvr said:

When I see a change this big it makes me think anything is possible.  The h5 change is pretty big for a 6 hour model difference.

What's it saying now? 

[stormtracker]

8 minutes ago, Bob Chill said:

I doubt many are thinking heavy snow event. The 12z euro yesterday was max potential and unlikely. We've had plenty of similar type of events in the past. Usually a burst of snow that can over perform sometimes but usually in the 1-5" range tops followed by a flip and countdown to a drip fest. Flips usually happen earlier than we want and the drip fest Usually starts later than forecast. That actually sounds like a good forecast. I'll go with that for now. Lol

Yeah, I think most of us know we're not going to get a pure snow bomb.  At this point, wintry weather is what we're after.   If we can get 2-4 with some glaze before the switch, that'll do.  Of course we all want more.

[nflwxman]

Just now, stormtracker said:

Yeah, I think most of us know we're not going to get a pure snow bomb.  At this point, wintry weather is what we're after.   If we can get 2-4 with some glaze before the switch, that'll do.  Of course we all want more.

Four inches in December would be a win.  Though most are predicting a warm February, there really isn't any major ENSO or PDO driver, so I'm calling the rest of the winter a coin flip.