January 2020 Mid/Long Term Discussion

[HighStakes]

4 minutes ago, Ji said:

Mjo somehow just dies right before the promised land. The cards are lining up for one of those winters that just wont snow

The cards are lining up for what will most likely be a typical winter for our region. It will snow, just not nearly as much as we want most likely. Stop acting like we live in Watertown NY. 

[wdcrob]

I'm not a met/forecaster, but over the last 10 years I've gotten to be a decent META forecaster.  My forecasting rules, for other non-mets:

1) If Bob Chill and psuhoffman agree on a forecast it's likely to verify.  Both are extremely level-headed and keep emotion out of their thinking.

2) There are a number of otherwise sane, intelligent and knowledgeable people, including forecasters, who are so afraid of it NOT snowing they downplay the chances of snow even when it's likely.  I'll spare them blushes by not listing them, but ignore their negative comments.

3) Any forecast discussion that includes a lot of people saying IF in front of [something not currently happening or not currently modeled] is unlikely to result in significant snow.  If it feels like grasping, it usually is.

4) Related to 3... if the serious posters and forecasters disagree with each other about events inside 48-72 hours it's unlikely to snow significantly.

5) Most of the big/historic storms are telegraphed a week or more out and tend to be ~locked in at least 3-5 days ahead of time.

Some of this probably wrong, and there are obviously exceptions, but it's served me well when the discussions get technical.  Hopefully it's useful to other lurkers.

[psuhoffman]

What is frustrating is we keep cycling between the PAC and ATL taking turns crapping on us.  The pac looks to get pretty good for the next 2 weeks but the scandanavian ridge suddenly flips to a trough which allows more ridging to shift across into a position that could muck things up.  It's still not a bad look...but "one thing" keeps going wrong.  The thing is..that is normal.  Because to get snow we need so many more things to go right than wrong...that more often than not one thing will muck it up.  Kinda like a golf swing.  

[WinterWxLuvr]

3 minutes ago, Mersky said:

In my opinion if the pacific is crap 9 times out of 10 its a crap pattern no matter what the atlantic side looks like. The  pacific is the main driver so get a good pacific look and roll the dice. 

I agree. With a good pattern upstream we can get lucky even if the Atlantic is bad.

[Ji]

What is frustrating is we keep cycling between the PAC and ATL taking turns crapping on us.  The pac looks to get pretty good for the next 2 weeks but the scandanavian ridge suddenly flips to a trough which allows more ridging to shift across into a position that could muck things up.  It's still not a bad look...but "one thing" keeps going wrong.  The thing is..that is normal.  Because to get snow we need so many more things to go right than wrong...that more often than not one thing will muck it up.  Kinda like a golf swing.  

Wernt the Models recently showing a big nao in the 6-10 day window?

[psuhoffman]

5 minutes ago, Ji said:

55 minutes ago, psuhoffman said:

What is frustrating is we keep cycling between the PAC and ATL taking turns crapping on us.  The pac looks to get pretty good for the next 2 weeks but the scandanavian ridge suddenly flips to a trough which allows more ridging to shift across into a position that could muck things up.  It's still not a bad look...but "one thing" keeps going wrong.  The thing is..that is normal.  Because to get snow we need so many more things to go right than wrong...that more often than not one thing will muck it up.  Kinda like a golf swing.  

Wernt the Models recently showing a big nao in the 6-10 day window?

Briefly and it’s still there next week but it’s a wasted window (probably) because the trough axis is too Far East. Was about to post on that. Looks like a great chance for the southeast coast though. 

[Ji]

11 minutes ago, psuhoffman said:

Briefly and it’s still there next week but it’s a wasted window (probably) because the trough axis is too Far East. Was about to post on that. Looks like a great chance for the southeast coast though. 

i recently read that the SE has a high hit Rate in January when MJO is in phase 7

[poolz1]

1 minute ago, losetoa6 said:

12z Gfs really trying to build heights in the Nao region at hr 162 with energy undercutting the western ridge ..could be interesting 

Yeah....Either the gfs is up to its usual games or the idea of blocking in that region is just being picked up on again as we get closer. H180 is even more robust...

[jaydreb]

Results in a rainstorm verbatim in January   

 

[ryanconway63]

glad to see a storm on the GFS around the 24th but the way it unfolds is just so odd......thoughts?

[ryanconway63]

Just now, losetoa6 said:

Nice hit . Now let's just get it within 5 days 

its a hit but its primarily rain

[WxUSAF]

1 minute ago, ryanconway63 said:

its a hit but its primarily rain

Like everything about it screams classic I95 snowstorm and it’s rain to Scranton. I guess maybe that primary low starts too far N and erodes the mid levels before the coastal, but damn. 

[poolz1]

Almost 10 days out...I am fine with the gfs.  It seems to be making baby steps each run in the right direction.  We have gotten rid of the GL low that was on earlier runs and now made a move toward more HP in SE Can.  

[psuhoffman]

4 minutes ago, WxUSAF said:

Like everything about it screams classic I95 snowstorm and it’s rain to Scranton. I guess maybe that primary low starts too far N and erodes the mid levels before the coastal, but damn. 

There is "slightly" too much ridging to the northeast,  the h5 trough amplifies slightly too far west, the airmass is slightly too warm... a lot of very small imperfections combine to ruin it on this specific op run, but like I said yesterday this setup continues to be a "Ohio cow's fart in  the right direction" from being a big snowstorm for us.  There have been plenty of similar situations where at LONG leads the guidance thought what ended up a big snowstorm was a cold rain event.  I will take my chances on this setup.  It's the best one we have had yet this winter.  

[Its a Breeze]

Just now, psuhoffman said:

There is "slightly" too much ridging to the northeast,  the h5 trough amplifies slightly too far west, the airmass is slightly too warm... a lot of very small imperfections combine to ruin it on this specific op run, but like I said yesterday this setup continues to be a "Ohio cow's fart in  the right direction" from being a big snowstorm for us.  There have been plenty of similar situations where at LONG leads the guidance thought what ended up a big snowstorm was a cold rain event.  I will take my chances on this setup.  It's the best one we have had yet this winter.  

By far. 

Even with those small imperfections, there appears to be enough right, that if it were to verify as is (it won't) I'm having a very hard time believing there's THAT much rain...

 

Someone please start a thread!

[jaydreb]

GEFS also likes the Day 9-11 timeframe.  Mixture of acceptable hits and rain storms showing up.  

[psuhoffman]

@Ji @Ralph Wiggum

Was going to post this earlier this morning then got distracted with work.

But this is an example of how the overall long range guidance was right...but discreet features within the longwave pattern that are not discernible at long range will determine snow/no.  

For next week...the period Monday to Thursday...from long range it looked promising

Ridge bridge across the top, western ridge, eastern trough...this look could definitely work

The overall longwave pattern was pretty close but some details have shifted this to an unfavorable (for us) look

Still have the ridge bridge over the top and eastern trough but the system crashing into the Pac NW is shifting the western ridge too far east and that shifts the eastern trough too far southeast...this is now a good look for a possible snow for places in the southeast, maybe the outer banks.  Doesn't mean they get snow...but they have a chance which is super rare in itself.  The slight error on a specific feature that will not be resolved at day 10-15 shifted this from a very good look for snow to a cold/dry one for us.   The guidance wasn't wrong or bad...we just can't see the details that will determine our fate wrt snow from that range.  Only the general longwave pattern.  Even in a good pattern we need luck with the discreet features.  Only a relatively narrow area will actually get snow in any given (short) time period.  The coverage of snow with a storm isnt that large typically.  Or the difference between a wave amplifying or getting squashed isnt that big on a hemispheric pattern scale.  Too many people assume if we get the good pattern it means we get snow.  Not the case.  

[psuhoffman]

Here is how the look for around day 10-12 has shifted on the GEFS (EPS is similar).   Now this time we are comparing a day 15 look to day 10..(last time it was day 10 to 7) so the shifts are going to be a bit more drastic...but still the large scale longwave pattern wasn't awful.

GEFS from a few days ago

This was a very cold look, big EPO ridge with cross polar flow directed right into the eastern US.  But it's also a dry one, and I mentioned that a few days ago when this look was being tossed out.  This was likely to be very cold but very dry.  The other 2 major features were the PV situated across the NAO domain across the pole into the Kara region, eastern trough, trough in the Pac NE of Hawaii.  

This is how it has shifted 

So again it was too far west with the pac trough...this shift pressed the epo ridge into more of a Hudson Bay ridge.  It was correct with its NAM depiction and the trough in the east.   Now this has a positive and a negative.  It cuts off the cross polar flow, so this is a much less cold look.   But this is also much more likely to get something to amplify into the southeastern US.  That blocking ridge across Canada will cut off arctic cold but there is a shot of cold into the east ahead of this...and so long as that is trapped under the block and not scoured out that usually is good enough in January.  Ideally I would like a 50/50...that could end up being the big issue here if too much ridging in the northeast allows the system to cut... but this still has potential imo.  

This is a composite of 16 warning level snowfalls at BWI with a Hudson Bay centered ridge. 

The obvious thing missing is the 50/50 low.  But that is a composite, not ALL 16 of those had a 50/50, but most hence the mean.  But at this range a feature like that could be missed, perhaps an unseen vort next week, Ralphs clipper, can bomb out into the 50/50 space, or perhaps the day 11 storm does cut but becomes the 50/50 for the day 14 threat.  Either way, this look is way closer to a big snow look than the one a few days ago.  It's not nearly as cold...and it could end up a rain look also...but you have to play with fire to have a nice BBQ!  

If you did want a week of frigid cold dry weather...I apologize, things are not moving in the right direction for that.  

 

 

[HighStakes]

14 minutes ago, psuhoffman said:

Here is how the look for around day 10-12 has shifted on the GEFS (EPS is similar).   Now this time we are comparing a day 15 look to day 10..(last time it was day 10 to 7) so the shifts are going to be a bit more drastic...but still the large scale longwave pattern wasn't awful.

GEFS from a few days ago

This was a very cold look, big EPO ridge with cross polar flow directed right into the eastern US.  But it's also a dry one, and I mentioned that a few days ago when this look was being tossed out.  This was likely to be very cold but very dry.  The other 2 major features were the PV situated across the NAO domain across the pole into the Kara region, eastern trough, trough in the Pac NE of Hawaii.  

This is how it has shifted 

So again it was too far west with the pac trough...this shift pressed the epo ridge into more of a Hudson Bay ridge.  It was correct with its NAM depiction and the trough in the east.   Now this has a positive and a negative.  It cuts off the cross polar flow, so this is a much less cold look.   But this is also much more likely to get something to amplify into the southeastern US.  That blocking ridge across Canada will cut off arctic cold but there is a shot of cold into the east ahead of this...and so long as that is trapped under the block and not scoured out that usually is good enough in January.  Ideally I would like a 50/50...that could end up being the big issue here if too much ridging in the northeast allows the system to cut... but this still has potential imo.  

This is a composite of 16 warning level snowfalls at BWI with a Hudson Bay centered ridge. 

The obvious thing missing is the 50/50 low.  But that is a composite, not ALL 16 of those had a 50/50, but most hence the mean.  But at this range a feature like that could be missed, perhaps an unseen vort next week, Ralphs clipper, can bomb out into the 50/50 space, or perhaps the day 11 storm does cut but becomes the 50/50 for the day 14 threat.  Either way, this look is way closer to a big snow look than the one a few days ago.  It's not nearly as cold...and it could end up a rain look also...but you have to play with fire to have a nice BBQ!  

If you did want a week of frigid cold dry weather...I apologize, things are not moving in the right direction for that.  

 

 

You are on a roll today. Great job.  

[Weather Will]

GEFS WB Probabilities of 3 inches or more through the following weekend.  Most of this potential in the DMV is the result of the potential for a storm as depicted for NEXT weekend.  

[87storms]

1 hour ago, Mersky said:

Give me a low in that location and a high in that spot and worry about details later . 

there appears to be more blocking in canada for that storm as opposed to this upcoming weekend where the system is just cutting through the path of least resistance into the midwest.  timing will be key again.  may even want that next system to slow down a notch.

[CAPE]

57 minutes ago, 87storms said:

there appears to be more blocking in canada for that storm as opposed to this upcoming weekend where the system is just cutting through the path of least resistance into the midwest.  timing will be key again.  may even want that next system to slow down a notch.

Higher heights over the Canadian Maritimes rather than  lower heights(ideal) is the biggest issue with this threat at as depicted at range. The track is about perfect, and everything else is decent enough, and there is plenty of time for features to get tweaked a bit, hopefully in the favorable direction.

[CAPE]

Pretty significant improvement on the 12z GEFS for the 25-30th window.

 

[Ji]

Euro has a big high in a great place but still rain

[H2O]

1 minute ago, C.A.P.E. said:

Pretty significant improvement on the 12z GEFS for the 25-30th window.

 

A couple blogs I read have started to point to that time frame as well.  Too soon for specifics

[Maestrobjwa]

8 minutes ago, Ji said:

Euro has a big high in a great place but still rain

How is that even possible, lol

[jaydreb]

Just now, Maestrobjwa said:

How is that even possible, lol

Not enough cold air and the track looks slightly too close to the coast?  PSU mentioned in earlier posts that the ridging in Canada cuts us off from cross polar flow of fresh cold air.  So we have to rely on whatever cold air has gotten trapped under the block, which may be stale by the time the storm arrives.  

[psuhoffman]

11 minutes ago, Ji said:

Euro has a big high in a great place but still rain

Yea but with a primary unto Pittsburgh and a secondary near Annapolis it wouldn’t matter. But the exact track at day 10 doesn’t matter either. The ingredients we need are all there. We just need them to come togterget properly. 

[psuhoffman]

14 minutes ago, C.A.P.E. said:

Pretty significant improvement on the 12z GEFS for the 25-30th window.

 

That is about as good a 5 day mean that far out will ever look.  We see higher ens means but it’s always either a close range threat or over a longer period that includes multiple threats. 

[Scarlet Pimpernel]

6 minutes ago, Maestrobjwa said:

How is that even possible, lol

Couple of things I can think of, just looking at that surface plot.  The coastal low is too far inland (and the high to the north looks pushed too far away to the north).  Also, note the extension of low pressure into the WV panhandle/southeast OH/southwest PA.  That would imply a primary that's too far north, thus enabling more warm air to get in before the coastal can take over.  Again, that's just based on looking at the surface, having not seen the corresponding Euro 500 hPa.

ETA:  Ninja'd by @psuhoffman and @jaydreb!