March 13/14th Storm Thread (Storm Mode)

[psuhoffman]

21 minutes ago, mitchnick said:

Probably old news, but I don't think the 0z JMA was mentioned to be an absolute snow bomb. Looks like 1.6-1.8" falls and still snowing but the maps with precip end.

Where do you see the 0z JMA?

[showmethesnow]

11 minutes ago, mitchnick said:

Here's a link starting at 48 hrs.

http://meteocentre.com/numerical-weather-prediction/map-explorer.php?mod=jma&run=06&stn=QQ500&hh=048&map=na&stn2=QQ500&run2=06&mod2=gemreg&hh2=048&comp=1&fixhh=1&lang=en&yyyy=latest&mm=latest&dd=latest&mode=latest&stn2_type=prog&date_type=dateo

Shame that is yesterdays run and it only goes out to 84. The look at 84 looks very promising with the stronger shortwave and the good separation between that and the northern portion of the trough just beginning to drop down. That would have probably been a very nice solution if extended.

Edit: just noticed they do have the later runs. Let me check them out.

[AlaskaETC]

1 minute ago, showmethesnow said:

Shame that is yesterdays run and it only goes out to 84. The look at 84 looks very promising with the stronger shortwave and the good separation between that and the northern portion of the trough just beginning to drop down. That would have probably been a very nice solution if extended.

If you click on available runs, you can get the latest one he mentions.

[SomeguyfromTakomaPark]

The 6z GFS is beautiful.  DC rides the freezing line the whole storm but it never actually crosses NW of the district.  A solid 10-15+ inches for our subforum using 10:1.   Nighttime with we heavy rates if that scenario played out we do fine.  Hoping the Euro is a hiccup and we see some good runs today to lock this up.   

[mitchnick]

2 minutes ago, showmethesnow said:

Shame that is yesterdays run and it only goes out to 84. The look at 84 looks very promising with the stronger shortwave and the good separation between that and the northern portion of the trough just beginning to drop down. That would have probably been a very nice solution if extended.

Edit: just noticed they do have the later runs. Let me check them out.

I intended to attach the 0z run,  but not sure that's what showed up. So I'll try again but if it doesn't say last night's 0z run, just adjust it on the drop down menu. 

http://meteocentre.com/numerical-weather-prediction/map-explorer.php?mod=jma&run=00&stn=PNMPR&hh=048&map=na&stn2=PNMPR&run2=18&mod2=jma&hh2=048&comp=1&fixhh=1&lang=en&yyyy=latest&mm=latest&dd=latest&mode=latest&stn2_type=prog&date_type=dateo

[pasnownut]

Trying to post JMA, but it does look tasty.

Shows 992 of VA coast.  ULL over central MI

Nut

[showmethesnow]

13 minutes ago, mitchnick said:

Here's a link starting at 48 hrs.

http://meteocentre.com/numerical-weather-prediction/map-explorer.php?mod=jma&run=06&stn=QQ500&hh=048&map=na&stn2=QQ500&run2=06&mod2=gemreg&hh2=048&comp=1&fixhh=1&lang=en&yyyy=latest&mm=latest&dd=latest&mode=latest&stn2_type=prog&date_type=dateo

Great look on the latest run of the JMA at 500mb. Plenty of separation between our storm and the NS energy and this results in a very nice solution for our region.

 

[pasnownut]

1 minute ago, showmethesnow said:

Great look on the latest run of the JMA at 500mb. Plenty of separation between our storm and the NS energy and this results in a very nice solution for our region.

 

So as the NAM is "useless" to some at this juncture, where would you rank the JMA?

Use it as a tool.....or is it a tool?

Nut

 

[showmethesnow]

Really hard to tell with the JMA but I think the qpf on it would be 2+ inches for dc/balt region. 

[showmethesnow]

1 minute ago, pasnownut said:

So as the NAM is "useless" to some at this juncture, where would you rank the JMA?

Use it as a tool.....or is it a tool?

Nut

 

Ji is the expert on the JMA, you should probably ask him. As far as myself I hardly ever look at it unless it gets posted but I do get the impression that though it is not the the Euro or GFS standards it is good enough that you don't want to just dismiss it out of hand.

[SomeguyfromTakomaPark]

Just now, PDIII said:

Hey.. I dont see anything.. and I am anything wrong with the 6z GFS.  Verbatim.. this was the best run of the winter for the GFS. Solid 12-18 inches up and down the I95 Corridor.  Thats approaching HECs. And it is inside 72 hours.  

The problem that exists that is causing all the anxiety is the gradient.  But I have news for you folks.... whoever is 10 miles northwest of that gradient is gonna get absolutely plastered.. such is life in the MA.

 

1 minute ago, PDIII said:

Exactly...

Like you said, coastal in March we're gonna have to deal with the gradient.  I'm in for this regardless of where it sets up.  I just hope the storm ends up 50 miles east of where the GFS has it so more of us can cash in.

[pasnownut]

4 minutes ago, showmethesnow said:

Ji is the expert on the JMA, you should probably ask him. As far as myself I hardly ever look at it unless it gets posted but I do get the impression that though it is not the the Euro or GFS standards it is good enough that you don't want to just dismiss it out of hand.

Yeah i've seen the references to his "expertise" over the years.

And your right....never dismiss a model that shows you what you want to see

Nut

[ers-wxman1]

Last year the euro retracted from bullish runs leading up to the Jan 22-23 blizzard. It suppressed totals. It happened for one to two runs then flipped back to heavy amounts in line with other guidance. This run might be a blip. But that was a January storm, during peak climatology for this area. March is tricky and temp profiles will be no different with this storm.

Any storm deepening at our latitude regardless of high pressure to the north will have some kind of mixing, changeover, right along 95...warm advection, mild ocean temps from a relatively warm winter and latent heat release from heavy precipitation. We all know the issues in March as well. This is dicey at best. 

[CAPE]

1 hour ago, showmethesnow said:

Just started glancing over it but the key feature I noticed is that there seems to be a little less interaction between the NS energy and the storm as it is moving into our region.

The highest qpf is pretty far offshore on the 6z GFS. The more easterly track solution may end up drier overall to the NW of the low, due to less interaction. Probably wont have as many p-type issues though.

I could be wrong, but because there is a distinctly separate SE low, it does not appear this will evolve to the point where the region ends up in some sort of no mans land, in between the coastal and the NS low.

[PDIII]

5 minutes ago, ers-wxman1 said:

Last year the euro retracted from bullish runs leading up to the Jan 22-23 blizzard. It suppressed totals. It happened for one to two runs then flipped back to heavy amounts in line with other guidance. This run might be a blip. But that was a January storm, during peak climatology for this area. March is tricky and temp profiles will be no different with this storm.

Any storm deepening at our latitude regardless of high pressure to the north will have some kind of mixing, changeover, right along 95...warm advection, mild ocean temps from a relatively warm winter and latent heat release from heavy precipitation. We all know the issues in March as well. This is dicey at best. 

I agree with you.. but one thing that we do have going in our favor is the antecedent cold.  This will be some of the coldest air of the season.  I dont really know anything about anything but it would seem to me that this would server two purpose:

1- delay change over to rain/ sleet

2- increased temperature gradient resulting in greater instability/ better rates.

 

[showmethesnow]

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

The higher qpf is pretty far offshore on the 6z GFS. The more easterly track solution may end up drier overall to the NW of the low, due to less interaction. Probably wont have as many p-type issues though.

I could be wrong, but because there is a distinctly separate SE low, it does not appear this will evolve to the point where the region ends up in some sort of no mans land in between the coastal and the NS low.

Famous last words, but my fears of that happening are minimal at this point. Even with some minimal interaction we should be fine though amounts may suffer a little. Now if I start to see the models move towards a phase of NS stream energy while the storm is still to our south then I will panic. At this point in time I see no way that would be of benefit to us. It would more then likely put us in the middle of the transition, as you said, and then we would have the enjoyment of watching those to our north get pounded. No thanks, not what I signed up for with this storm.

[H2O]

Would still like to see the euro get the NS at our 8/9 o'clock in relation to the coastal.  10/11 o'clock is cutting close for temps to warm for DC.  EPS/GFS ens help smooth things out and as we get past their usefulness getting each run from here on out to reduce the jumps in temps and precip will boost confidence.

[showmethesnow]

4 minutes ago, PDIII said:

I agree with you.. but one thing that we do have going in our favor is the antecedent cold.  This will be some of the coldest air of the season.  I dont really know anything about anything but it would seem to me that this would server two purpose:

1- delay change over to rain/ sleet

2- increased temperature gradient resulting in greater instability/ better rates.

 

While you definitely want this in place that really doesn't change the fact of what will cause the mixing issues. I have seen this time and time again over the 45+ years I have lived in this region. Everything looks great 850mb's down to the surface, and yet we will see mixing occur 50+ miles out from what was considered the all snow portion of a storm. These stronger storms with the long fetches from the southeast and east, almost every time, pull in sneaky warm layers above the surface that models have a hard time picking up. And these warm layers can extend quite far into the cold dome. Now quite often the layer is shallow and can be overcome with somewhat decent rates. But when the rates slacken a touch we will then see mixing of sleet and freezing rain reach the surface. These layers are thicker and warmer the closer you get to the transition line so the rates have to be greater there to overcome it. I myself fully expect that we will see more mixing around the transition line then now shown so i would not be surprised to see the snow totals lower then predicted. Even where I live, probably 75+ miles from transition, I would put my odds of mixing at some point at 25-33%.

[psuhoffman]

The overnight runs were good on the whole if we take the micro view. But stepping back to see the forest from the trees the threat of a screwjob might have increased some. The reason is a trend emerging in the northern stream system to be further north. 24 hours ago that feature was digging into Tennessee or at least southern KY. Now it's coming across Indiana into Ohio. 

That feature is pulling on the developing coastal and we need that so it doesn't escape but think about the direction of the tug.  If the low is in TN and the coastal forming off the Carolinas the tug is to the west.  This allows healthy precip to develop to the west.  But the further north the initial low is the more the tug becomes north and if that trend continues eventually we risk having the precip from the developing coastal pulled due north up the coast instead of NW and quickly shunted east of us.  

Remember my old illustration from early feb about why we don't want a low north of an stj low. It cuts off the circulation to the west so you can't get good moisture transport to the west of the track. Plus it messes with the thermals. We saw both to some extent in the overnight runs. 

While snowfall increased in the means for our specific locations they cut back to our west and precip drastically has been cutting down to our west the last few runs. If that trend continues, another 1-2 shifts like the last and it WILL start to effect us also as we are the furthest west and south of the big cities so most vulnerable to that. 

As of right now that trend hasn't hurt us YET.  But I don't want to have tunnel vision and ignore that either because if that continues it will.  Look at the last 3 gefs precip maps they are shifting east each run.  We would still likely get some snow but the heavy banding would get shunted up the coast east of us and we would miss out on the 10"+ stuff.  We need the northern stream system to stop trending north today.  That's what I'll be watching. 

 

[showmethesnow]

3 minutes ago, psuhoffman said:

The overnight runs were good on the whole if we take the micro view. But stepping back to see the forest from the trees the threat of a screwjob might have increased some. The reason is a trend emerging in the northern stream system to be further north. 24 hours ago that feature was digging into Tennessee or at least southern KY. Now it's coming across Indiana into Ohio. 

That feature is pulling on the developing coastal and we need that so it doesn't escape but think about the direction of the tug.  If the low is in TN and the coastal forming off the Carolinas the tug is to the west.  This allows healthy precip to develop to the west.  But the further north the initial low is the more the tug becomes north and if that trend continues eventually we risk having the precip from the developing coastal pulled due north up the coast instead of NW and quickly shunted east of us.  

Remember my old illustration from early feb about why we don't want a low north of an stj low. It cuts off the circulation to the west so you can't get good moisture transport to the west of the track. Plus it messes with the thermals. We saw both to some extent in the overnight runs. 

While snowfall increased in the means for our specific locations they cut back to our west and precip drastically has been cutting down to our west the last few runs. If that trend continues, another 1-2 shifts like the last and it WILL start to effect us also as we are the furthest west and south of the big cities so most vulnerable to that. 

As of right now that trend hasn't hurt us YET.  But I don't want to have tunnel vision and ignore that either because if that continues it will.  Look at the last 3 gefs precip maps they are shifting east each run.  We would still likely get some snow but the heavy banding would get shunted up the coast east of us and we would miss out on the 10"+ stuff.  We need the northern stream system to stop trending north today.  That's what I'll be watching. 

 

I can see what you are saying and agree with it to a point. But I also have to question whether the less iteration between the NS energy and the southern low would have a positive effect in countering the loss in tug from the west. With less interaction we would also hopefully see a corresponding response of the low being deeper and intensifying quicker which should also have the effect of pulling the track westward. I have to wonder if to a point this interaction is balancing itself out between the two.

[WxUSAF]

1 hour ago, dallen7908 said:

Verbatim the EURO for DCA is worrisome as the discussion above notes.  The big problem is the surface:

The snow begins at 10-11 PM with surface temperatures around 34.  Temperatures rise to 36/37 by 8 AM with ~0.8" of QPF before then; 1000-500 mb thicknesses look ok and remain less than 542. No sign of a warm nose (skew-T ok). However, temperatures rise to near 40 during the day as the snow lightens or switches to sleet/rain. 

Wrap-around light snow most of Wednesday with perhaps an inch. 

 

Glad to see that the 06 UT GFS and hear that the ECMWF ensembles are better (albeit slightly it appears)  than the operational EURO. 

 

If the surface is the only layer above freezing in the overnight hours, than I wouldn't sweat the Euro's temps *too* much yet.  Wet bulbs will be solidly below freezing before precip arrives.  If there was a 800mb warm layer even overnight, that's a bigger issue.  

[TowsonWeather]

9 minutes ago, showmethesnow said:

I can see what you are saying and agree with it to a point. But I also have to question whether the less iteration between the NS energy and the southern low would have a positive effect in countering the loss in tug from the west. With less interaction we would also hopefully see a corresponding response of the low being deeper and intensifying quicker which should also have the effect of pulling the track westward. I have to wonder if to a point this interaction is balancing itself out between the two.

Good post. It's seemed to me for awhile now that, as odd and messy as it seems, it's in our best interests to strike that balance - where there is SOME interaction between the NS and the southern stream, but not too much. 

If the setup was different (if this was all happening much further south, for example, or if there was a much stronger block in place), we might be rooting for a full and early phase, but as we stand this seems like the best outcome for us: enough interaction to keep the storm close to the coast, but not so much that it messes with the thermals or screws us with a messy energy transfer right on top of us.

[psuhoffman]

9 minutes ago, showmethesnow said:

I can see what you are saying and agree with it to a point. But I also have to question whether the less iteration between the NS energy and the southern low would have a positive effect in countering the loss in tug from the west. With less interaction we would also hopefully see a corresponding response of the low being deeper and intensifying quicker which should also have the effect of pulling the track westward. I have to wonder if to a point this interaction is balancing itself out between the two.

It's not all or nothing. But your getting into a delicate balancing act there. Not enough interaction and the northern stream wave becomes a kicker and the stj system shifts east like the ggem. 95 might actually like that as they "could" get the back edge of the ccb from the coastal and with no Ptype issues that could be good for them. But for us or those in northern va west of 95 that would be a disaster.  

Without any phasing the developing Ccb will be tight not expansive because it's getting interference on the nw side from the circulation of northern stream low cutting off its moisture feed inland. 

So there is a double edge sword. Too much phasing at the wrong time and it could delay the bombing of the southern low. Not enough and the southern low bombs but gets kicked east. Is there some magic perfect balance, sure, but I would rather simply get the northern stream system to dig more and not play with that fire.  Nothing good can come from it continuing to trend north. 

[Eskimo Joe]

3 minutes ago, psuhoffman said:

It's not all or nothing. But your getting into a delicate balancing act there. Not enough interaction and the northern stream wave becomes a kicker and the stj system shifts east like the ggem. 95 might actually like that as they "could" get the back edge of the ccb from the coastal and with no Ptype issues that could be good for them. But for us or those in northern va west of 95 that would be a disaster.  

Without any phasing the developing Ccb will be tight not expansive because it's getting interference on the nw side from the circulation of northern stream low cutting off its moisture feed inland. 

So there is a double edge sword. Too much phasing at the wrong time and it could delay the bombing of the southern low. Not enough and the southern low bombs but gets kicked east. Is there some magic perfect balance, sure, but I would rather simply get the northern stream system to dig more and not play with that fire.  Nothing good can come from it continuing to trend north. 

This sums up my fears well.  If the 12z runs continue to judge north with the Ohio Valley low then we all know a fail is likely for DC.  A southern shift with that energy back to the KY/VA/OH border would be ideal.

[showmethesnow]

1 minute ago, psuhoffman said:

It's not all or nothing. But your getting into a delicate balancing act there. Not enough interaction and the northern stream wave becomes a kicker and the stj system shifts east like the ggem. 95 might actually like that as they "could" get the back edge of the ccb from the coastal and with no Ptype issues that could be good for them. But for us or those in northern va west of 95 that would be a disaster.  

Without any phasing the developing Ccb will be tight not expansive because it's getting interference on the nw side from the circulation of northern stream low cutting off its moisture feed inland. 

So there is a double edge sword. Too much phasing at the wrong time and it could delay the bombing of the southern low. Not enough and the southern low bombs but gets kicked east. Is there some magic perfect balance, sure, but I would rather simply get the northern stream system to dig more and not play with that fire.  Nothing good can come from it continuing to trend north. 

No doubt we are riding a somewhat fine balancing act here. But I do believe we have some play as the different factors balance each other out to a point in regards to the interaction between the NS and the storm. Now if we begin to see solutions that trend somewhat moderately in one direction or the other then that would be of concern.

[psuhoffman]

I should have prefaced all this by saying I'm not thinking this "screwed scenario" happens. I'd maybe peg it at only 25% but that is higher then I'm comfortable with.   I'm simply pointing out a troubling trend that we should want to see stop today. But I'm not fatalistic. Trends don't continue forever. They can stop anytime and as we get closer the guidance should be honing in on the solution so there is a chance they are close to getting it and we don't see any further shift in that direction. All I'm saying though is at this time, that trend if it were to continue would be the biggest threat to us not getting big snow totals. 

[Joshfsu123]

5 minutes ago, TowsonWeather said:

Good post. It's seemed to me for awhile now that, as odd and messy as it seems, it's in our best interests to strike that balance - where there is SOME interaction between the NS and the southern stream, but not too much. 

If the setup was different (if this was all happening much further south, for example, or if there was a much stronger block in place), we might be rooting for a full and early phase, but as we stand this seems like the best outcome for us: enough interaction to keep the storm close to the coast, but not so much that it messes with the thermals or screws us with a messy energy transfer right on top of us.

Seems to me the 06z GFS had what you are describing here somewhat. Enough interaction to keep the low near the coast (altho in a slightly better (east) location than the 00z) but also not enough interaction to destroy the temps completely - 850s stay good. The low still manages to make it to Ohio but looks slightly weaker on 06z... so it's a balancing act for sure.

[MD Snow]

2 minutes ago, psuhoffman said:

I should have prefaced all this by saying I'm not thinking this "screwed scenario" happens. I'd maybe peg it at only 25% but that is higher then I'm comfortable with.   I'm simply pointing out a troubling trend that we should want to see stop today. But I'm not fatalistic. Trends don't continue forever. They can stop anytime and as we get closer the guidance should be honing in on the solution so there is a chance they are close to getting it and we don't see any further shift in that direction. All I'm saying though is at this time, that trend if it were to continue would be the biggest threat to us not getting big snow totals. 

I started seriously taking this scenerio into account after the Euro last night. Saw the 6z GFS cut back on snow totals to our south and west. 

It's interesting to see the NAM come into range showing a stronger and more further north NS LP and watch the globals follow to an extent. I think the GGEM is still out to lunch but it was showing the least interaction between the NS and SS. The next 3 model runs will be crucial in seeing if this continues to be a trend. If it does then people DC south and west should be a little worried. Not there yet though. 

[psuhoffman]

3 minutes ago, showmethesnow said:

No doubt we are riding a somewhat fine balancing act here. But I do believe we have some play as the different factors balance each other out to a point in regards to the interaction between the NS and the storm. Now if we begin to see solutions that trend somewhat moderately in one direction or the other then that would be of concern.

The balance works because the northern stream system is west of the coastal low "enough" to exert that west tug we need and pull the storm up along the coast and also pull in precip along the inverted trough connecting the two. 

But that balance will no longer work in our favor if the northern stream low continues to trend north and ends up near Lake Erie for instance. No matter how the balance goes it would be harder to help us. The increased distance would lower the tug and could allow the low to escape out to sea. Even if the tug is good it's now in the wrong direction pulling the precip more north then northwest and cutting off a healthy Ccb development west of the low. And it's pulling warm air up. I just don't see any net positive in that scenario.  The balance your talking about will not work if the primary low gets much further north. That's my worry. 

[showmethesnow]

Just now, psuhoffman said:

I should have prefaced all this by saying I'm not thinking this "screwed scenario" happens. I'd maybe peg it at only 25% but that is higher then I'm comfortable with.   I'm simply pointing out a troubling trend that we should want to see stop today. But I'm not fatalistic. Trends don't continue forever. They can stop anytime and as we get closer the guidance should be honing in on the solution so there is a chance they are close to getting it and we don't see any further shift in that direction. All I'm saying though is at this time, that trend if it were to continue would be the biggest threat to us not getting big snow totals. 

I am not sure we can even call it a trend. Not going to go back through old runs to verify this but if I recall correctly we have seen the handling of the NS feature shift back and forth quit often over the last couple of days. I have to wonder if the goal posts have been somewhat set with the outliers and the solution would hopefully fall in between. If that is indeed the case, even with both outliers we do well in the region with the best possible outcome probably a compromise between the two. At this point I like where we stand and barring any major shifts think our region will do well.