Mid to Long Term Discussion 2017

[bhamwx205]

12z eps

last night's 00z with a nice SE trend with the storm track

Sent from my SM-G900V using Tapatalk

[Jon]

Euro weeklies are better. Mean had a snow mean for next weeks system quite like the 00z snow mean. Also fwiw the mean improved on the 00z EPS vs the 12z EPS, so the Euro ensembles "found" the storm again I guess you would say.

Weeklies mid month go to a ridge but around Jan 30 brings a very favorable pattern w/ +PNA and blocking with hints at a trough in the east. Mean snow for RDU is 5" thru Feb 12.


Sent from my iPhone using Tapatalk

[Jon]

As other have said we just want the storm signal at this range. We want the overall pattern to be able to produce a storm. Details should be looked at within 5 days.  

Right now most people need to be looking at 500mb vort maps. It can tell you a lot about evolution of the storm and how then models are handling it. All I see are posts about snow. If I had time I would but I'm swamped at work.

Wow - break out some more vorticity analysis plz.


Sent from my iPhone using Tapatalk

[Jonathan]

13 minutes ago, FallsLake said:

As other have said we just want the storm signal at this range. We want the overall pattern to be able to produce a storm. Details should be looked at within 5 days.  

I think by now we know there's a storm signal. Not really looking for deets right now I was more thinking out loud. It'll be interesting to see what type/duration of storm we end up seeing as we get into next week. I just hope the blocking holds. This could be a potential heartbreaker or a surprising system.

[bhamwx205]

Right now most people need to be looking at 500mb vort maps. It can tell you a lot about evolution of the storm and how then models are handling it. All I see are posts about snow. If I had time I would but I'm swamped at work.

Wow - break out some more vorticity analysis plz.

Sent from my iPhone using Tapatalk

it's kinda simple really. the slower the evolution with the energy out west the better. we need to let the cold air establish itself first. you can the difference in the eps. the 12z eps was much faster with the energy putting more energy into the first wave thus the track shifted a little NW as it rode the arctic boundary . the 00z eps was much slower with the energy allowing the boundary more time to settle in so when the energy finally came the system shifted SE vs the 12z run

Sent from my SM-G900V using Tapatalk

[BristowWx]

3 minutes ago, Jonathan said:

I think by now we know there's a storm signal. Not really looking for deets right now I was more thinking out loud. It'll be interesting to see what type/duration of storm we end up seeing as we get into next week. I just hope the blocking holds. This could be a potential heartbreaker or a surprising system.

It would be nice if we all could get a storm north to south.  But what is good for some us is not for others.  One thing I noticed on the 500 plot for 6z op was the flat look.  Have to wonder if the strong push from north is shearing the first wave.  My gut tells me a south solution vice wound up cutter is more likely.  Anyone's guess now. 12z runs will be interesting 

[SnowNiner]

2 minutes ago, bhamwx205 said:

it's kinda simple really. the slower the evolution with the energy out west the better. we need to let the cold air establish itself first. you can the difference in the eps. the 12z eps was much faster with the energy putting more energy into the first wave thus the track shifted a little NW as it rode the arctic boundary . the 00z eps was much slower with the energy allowing the boundary more time to settle in so when the energy finally came the system shifted SE vs the 12z run

Sent from my SM-G900V using Tapatalk

Yes, my concern is with even the slower solutions we see, the temps are pretty marginal for the upstate area.  If I'm 40 north I'm feeling pretty decent on this one.  

[Brick Tamland]

Ideal scenario would be some overrunning at first to lock in the cold, then a more consolidated system with more precip coming afterwards. Looks like the models might be trending towards this, too.

[PackGrad05]

The GFS does not look cold enough at all, especially for Saturday.  (for RDU)

[mackerel_sky]

7 minutes ago, PackGrad05 said:

The GFS does not look cold enough at all, especially for Saturday.  (for RDU)

Meh, 6z GFS looked close to 0z Euro, in my opinion! Light, drawn out event, NW fringe kind of slop

[mackerel_sky]

Upon looking at the GFS para, 0z, which is said to have verification along the lines of Euro, most should be excited!

[Upstate Tiger]

KGSP is mentioning the potential for next weekend.  Frankly, it is pretty remarkable for them to mention a potential winter event 7 days out.  Of course, these discussions are created by different individual NWS forecasters (depending on the shift) who have their own personalities when it comes to what they are willing to share.  Nevertheless, it's good to see this from them.....

The new guidance generally dries out the
western Carolinas in the wake of the upper wave thru mid-week, but
the real story here will be the pattern change to something more
typical of dead-of-winter with a large positively-tilted upper trof
from the southwestern U.S. to an expansive deep upper low over
Ontario/Hudson Bay. This feature will result in a large negative
height anomaly that allows Arctic air to spill well down into the
U.S. east of the Rockies. Down in these parts, we end up essentially
in a nearly-zonal flow aloft by mid week that typically causes
timing/strength issues with disturbances moving rapidly east. The
problem will be that the western Carolinas will be perilously close
to the edge of the air of arctic origin, meaning that if something
were to come along in this fast flow regime it could result in a
winter precip event. Lo and behold, both operational models have
some flavor of that scenario developing Thursday night into Friday.
It is way too early to get excited about this and uncertainty is
very high, but uncertainty is NOT that high about how much cold air
will be in closer proximity than usual late in the week, which means
our potential for winter weather is about to go up. Stay tuned!

[BullCityWx]

Euro was actually quite nice here. Went from ZR to IP to SN. Temps near zero on Sunday morning across the foothills, around 6 here.

[Cold Rain]

10 minutes ago, Queencitywx said:

Euro was actually quite nice here. Went from ZR to IP to SN. Temps near zero on Sunday morning across the foothills, around 6 here.

That's the kind of progression that I remember occurring more frequently growing up....Liquid to snow or mix to snow.  Seems like most events now are snow to mix or snow to rain.  But I remember many winter events that changed to accumulating snow after an initial burst of rain.  That was always more exciting to me than the reverse.

[Brick Tamland]

4 minutes ago, Cold Rain said:

That's the kind of progression that I remember occurring more frequently growing up....Liquid to snow or mix to snow.  Seems like most events now are snow to mix or snow to rain.  But I remember many winter events that changed to accumulating snow after an initial burst of rain.  That was always more exciting to me than the reverse.

Everything was better in the 80s. 

[calculus1]

1 hour ago, BristowWx said:

It would be nice if we all could get a storm north to south.  But what is good for some us is not for others.  One thing I noticed on the 500 plot for 6z op was the flat look.  Have to wonder if the strong push from north is shearing the first wave.  My gut tells me a south solution vice wound up cutter is more likely.  Anyone's guess now. 12z runs will be interesting 

Not pick on you specifically, BristowWx, because many posts point to the same sentiment, but does anyone ever say the opposite of your bolded statement before the next iteration arrives?  For instance, "00z runs will be boring."  We always look expectantly for the next set of model runs, and they are always eagerly anticipated.  It is only after they arrive that we decide whether we want to put more or less weight on that particular run depending on whether the outcome is favorable to our desired solutions.  Anyway, I read that same statement multiple times prior to each potential storm during the winter, and I always find it rather funny.

[Jon]

6z GFS was overall very similar to 0z except further south and with even less overall accumulation across the board. (But more in E NC)

Wonder if this will end up trending back into a stronger, more consolidated system as we get closer? Need to tread lightly however between stronger storm with possible higher accumulations that could cut vs a weaker wave with less accumulation but with less chance to cut.

If we don't get enough cold I'm not sure a weaker energy event would be better. Assuming current modeled cold we'd almost want a more amplified system, it won't cut to the Lakes but stay a little inland, could give heavy snows on the western fringe to many in the SE upon exit instead of just a small event in northern counties. If we had decent CAD I'd be singing another tune...we really need more cold air.


Sent from my iPhone using Tapatalk

[mackerel_sky]

14 minutes ago, Cold Rain said:

That's the kind of progression that I remember occurring more frequently growing up....Liquid to snow or mix to snow.  Seems like most events now are snow to mix or snow to rain.  But I remember many winter events that changed to accumulating snow after an initial burst of rain.  That was always more exciting to me than the reverse.

I remember a few of those! But as with any system, waiting on the cold air to catch moisture, is a dangerous game, with lots of losers! As Jon stated, if we could just get the cold ahead of the storm!

[RiftMania]

1 hour ago, Jon said:

Right now most people need to be looking at 500mb vort maps. It can tell you a lot about evolution of the storm and how then models are handling it. All I see are posts about snow. If I had time I would but I'm swamped at work.

Wow - break out some more vorticity analysis plz.


Sent from my iPhone using Tapatalk

Sounds reasonable to me, I'm no expert but I have a feeling all will be happy with the end result. However, I'm not saying all will be happy with snow totals.

[ajr]

45 minutes ago, mackerel_sky said:

Upon looking at the GFS para, 0z, which is said to have verification along the lines of Euro, most should be excited!

Is it the position of the HP in Ohio-Penn in the 198-210hr range that you're looking at?

[SnowNiner]

10 minutes ago, Jon said:

If we don't get enough cold I'm not sure a weaker energy event would be better. Assuming current modeled cold we'd almost want a more amplified system, it won't cut to the Lakes but stay a little inland, could give heavy snows on the western fringe to many in the SE upon exit instead of just a small event in northern counties. If we had decent CAD I'd be singing another tune...we really need more cold air.


Sent from my iPhone using Tapatalk

Amen! The last few years we've been fortunate to have nice CAD in place that worked in our favor.  And over time, the model runs would get colder, colder, and colder. I remember many times a freezing rain forecast for CLT often turned to sleet/snow.  Most runs of this threat the CAD is ominously absent.  That worries me greatly where I could see Tennessee and MS/AL getting the cold on the west side of the Apps, while east of them struggle. 

[griteater]

Looking at the last 2 Euro Ensemble runs, I count roughly 13-15 of the 51 members with what I would consider a decent or good hit for portions of our forum...a higher number than that for NW corner of NC.  For central and northern VA, it's roughly 23-27 members with hits.  I think that's a fair barometer as to the winter storm chances for each region as of now.

[griteater]

2 minutes ago, SnowNiner said:

Amen! The last few years we've been fortunate to have nice CAD in place that worked in our favor.  And over time, the model runs would get colder, colder, and colder. I remember many times a freezing rain forecast for CLT often turned to sleet/snow.  Most runs of this threat the CAD is ominously absent.  That worries me greatly where I could see Tennessee and MS/AL getting the cold on the west side of the Apps, while east of them struggle. 

Unfortunately, it's always a delicate balance as you know.  You don't want to see a damming high that starts retreating with a storm plowing in from the SW.

[BristowWx]

6 minutes ago, griteater said:

Looking at the last 2 Euro Ensemble runs, I count roughly 13-15 of the 51 members with what I would consider a decent or good hit for portions of our forum...a higher number than that for NW corner of NC.  For central and northern VA, it's roughly 23-27 members with hits.  I think that's a fair barometer as to the winter storm chances for each region as of now.

Thanks.  That's a nice breakdown.  I fear suppression more than amped up cutter.   Supresson would be good for SC certainly.  

[SnowNiner]

3 minutes ago, griteater said:

Unfortunately, it's always a delicate balance as you know.  You don't want to see a damming high that starts retreating with a storm plowing in from the SW.

Would you not want that?  We're always worried about how fast the damming high retreats off the coast for sure, but when it's there, at least for a time, it fuels the cold we need for winter precip.  

Why is this set up not producing a high to our NE Grit? You'd think with some blocking and a 50/50 low we've have some good confluence from the NE.  Seems like the missing key here, or I'm out in left field probably. 

[mackerel_sky]

15 minutes ago, ajr said:

Is it the position of the HP in Ohio-Penn in the 198-210hr range that you're looking at?

I'm just going off snowfall maps

[griteater]

3 minutes ago, SnowNiner said:

Would you not want that?  We're always worried about how fast the damming high retreats off the coast for sure, but when it's there, at least for a time, it fuels the cold we need for winter precip.  

Why is this set up not producing a high to our NE Grit? You'd think with some blocking and a 50/50 low we've have some good confluence from the NE.  Seems like the missing key here, or I'm out in left field probably. 

Oh yeah, I always want to see the damming high.  Ideally there's a dual high, one over the Midwest and another over the NE.

On the image, the big polar trough that is centered north of the Great Lakes...ideally, that would be positioned a little more to the SE (even better would be a big blocking ridge to the north of it).  In it's current position, the parent sfc high is stuck behind it in the Pacific NW and isn't able to move to the east in time ahead of the SW wave that kicks out

[Cold Rain]

The problem is that with a big trough on the west coast, the arctic air mass can NOT press into the SE without one of two things:

1) A well-timed west-based block/-NAO around Greenland, ridging into eastern Canada.  This will suppress heights in the east and counter the SE ridge, which will want to pop in response to the trough in the west.

2 ) A southward-displaced 50/50 low or PV (this usually remains far enough south and hangs around long enough when you have west-based blocking of sufficient strength as described above).  When this feature is present and far enough to the south, confluence will set up over the NE US and will lock in high pressure.  If this feature moves out too rapidly, then HP will move off the coast quickly, leaving you with a weak, insitu damming event, unless perfectly timed.

What you're seeing on the models is that the block near Greenland is oriented too far too the east.  So, that either HAS to change so that it can suppress and hold in the 50/50 low, or we need perfect timing of all features, which will create a narrow window for wintry precip, outside of the mountains and far northern sections.  Otherwise, that low will move up into eastern Canada, leaving the SE ridge room to flex and keep the arctic front stalled NW of our area.  This process is illustrated on the 0z Euro below:

At 144 (top 2 panels), you see ridging in the north Atlantic setting up (top left).  You see the big ULL/PV lobe over the Lakes moving east/NE.  You see the big trough out west and a fairly flat SE ridge (because the PV is currently over the Lakes).  You see the arctic front pressing south (top right).  High pressure is way out west, though.

At 168 (bottom 2 panels), you see the Atlantic ridge ridging toward Greenland.  It appears to be just a little too weak and too far to the east to trap the PV, which pulls off to the NE, thus allowing the SE ridge to flex and stall the arctic front.  High pressure is still too far west.

At 192 (top 2 panels), you see ridging in the north Atlantic still too far to the east and not oriented appropriately to suppress the PV, which escapes into far northeastern Canada.  The SE ridge is flexing in response to the trough out west, with nothing to squash it far enough south.  This allows the arctic front to remain hung up around the upper SE.

At 216 (bottom 2 panels), a wave moves through, bringing a reinforcement of the arctic air mass, which propels the front through the area.  Of course, the precip is ending/has ended.  The SE ridge has been pushed off to the east.  You still have an east-based -NAO configuration, but if you look out west, you see some changes taking shape.  You have a nice -EPO signal, along with a cutoff low underneath the Aleutian block.  This enables heights to rise over the SW US and creates an active southern storm track.  This eliminates the SW trough, which also eliminates the SE ridge.  IMO, this is starting to look like a favorable wintry pattern for the SE US, if it turns out to be real.

[SnowNiner]

^Thanks Grit

[cbmclean]

OK.  Setting aside what may or may not happen with the storm, what do the models say about general long-term temp trends over Eastern North America?