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February 12-13 Storm, Part III: Trilogy ends and then Obs thread soon!

stormtracker

By stormtracker,
in Mid Atlantic

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winterymix

winterymix

Posted
Posted

When Kocin posted his maps yesterday, that was his nod and wink.

He saw a pattern with excellent potential.

I think we all need to adjust our expectations to match climatology.

If most get 4" to 8" with some mixing, be happy.  If it overperforms,

be happy but realize we may wait another year or three before it happens again.

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dtk

dtk

Posted
Posted

agree 100 % that strong convection can rob moisture from a system. What I have a problem with is not how the QPF field is screwed with, but the emergence of strong convection in the first place. None of the dynamics support it.

 

Here is 30 hours h5, for when that panel I posted is valid starting QPF time, where do you see any lifting mechanism to support strong convection off the coast like that? UL support is way down in GA

Convective precipitation isn't necessarily driven by the main (upper level) large scale dynamic forcing.  I would have to look at profiles, cap, and then find the trigger(s).  The convection looks to be driven from the bottom, since at hour 30 there is strong low level warm advection, some frontogenetical forcing, and perhaps some low level convergence.  With the correct profiles, the model has no choice but to trigger convection in the warm sector to adjust.

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mitchnick

mitchnick

Posted
Posted

UKIE is lockstep with 12Z for those confused. Not drier

and CBB still at work at 48 hrs too

700mb RH

http://vortex.plymouth.edu/cgi-bin/gen_grbcalc2.cgi?re=us&id=&zoom=.6&ti=0≥=1280x1024&mo=ukmet≤=700&va=rhum&in=5&pl=cf&ft=h48&cu=latest&overlay=no&mo=≤=&va=&in=&pl=ln&ft=h24&cu=latest

850mb RH

http://vortex.plymouth.edu/cgi-bin/gen_grbcalc2.cgi?re=us&id=&zoom=.6&ti=0≥=1280x1024&mo=ukmet≤=850&va=rhum&in=5&pl=cf&ft=h48&cu=latest&overlay=no&mo=≤=&va=&in=&pl=ln&ft=h24&cu=latest

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Ian

Ian

Posted
Posted

not really. the h5 was not supportive of a big hit until tonights run

not sure how you come to that conclusion but here's 6z and 12z. CIPS has been spitting out big hits for days from the GFS even though it's looked pretty meh.

 

post-1615-0-00969700-1392178667_thumb.gi

 

post-1615-0-76400100-1392178659_thumb.gi

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WxMan1

WxMan1

Posted
Posted

If you had to pick one model that has been pretty consistent with this system, beginning on FRIDAY (6 days out)...

 

I think it would have to be the UKMet.  Actually for a while, the UK and CMC were steady as she goes until the CMC went farther west with the SLP track 12Z today.

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yoda

yoda

Posted
Posted

Not much QPF after I would surmise though IMO... prob 2-3mm more

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mitchnick

mitchnick

Posted
Posted

If you had to pick one model that has been pretty consistent with this system, beginning on FRIDAY (6 days out)...

 

I think it would have to be the UKMet.  Actually for a while, the UK and CMC were steady as she goes until the CMC went farther west with the SLP track 12Z today.

RGEM came back east some tonight so CMC will "probably" do the same

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ohleary

ohleary

Posted
Posted

I don't think we need a reason to throw out the GFS QPF....It is an outlier...that is reason enough...I don't think anyone who has followed the model evolution of this storm can say much positive about the GFS or put any faith in it at all....I am looking forward to the upgrades...

 

Agree with the first bolded.  Regarding the second bolded, anyone who isn't just forecasting on a forum is looking seriously at it.  It's now not showing much that other models aren't save for low qpf.  At this point take from it what is helpful and leave the details to the mesoscale models..this system the devil is in the details, not something a lower res model will necessarily handle well within 24 h.

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winterymix

winterymix

Posted
Posted

Convective precipitation isn't necessarily driven by the main (upper level) large scale dynamic forcing.  I would have to look at profiles, cap, and then find the trigger(s).  The convection looks to be driven from the bottom, since at hour 30 there is strong low level warm advection, some frontogenetical forcing, and perhaps some low level convergence.  With the correct profiles, the model has no choice but to trigger convection in the warm sector to adjust.

So why are the precipitation maps so different for the NAM compared to the GFS?

I thought the NAM was skillful with modeling temperature as well as warm and cool convection.

Which model is more believable for this storm?

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dtk

dtk

Posted
Posted

I don't think we need a reason to throw out the GFS QPF....It is an outlier...that is reason enough...I don't think anyone who has followed the model evolution of this storm can say much positive about the GFS or put any faith in it at all....I am looking forward to the upgrades...

Yeah, it hasn't performed particularly well.  My commentary on DA, model physics, interpretation of "convective feedback", etc., is only to help get rid of some commonly overused (and misused) justification for tossing model integrations that people don't like.

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vinylfreak89

vinylfreak89

Posted
Posted

not sure how you come to that conclusion but here's 6z and 12z. CIPS has been spitting out big hits for days from the GFS even though it's looked pretty meh.

 

attachicon.gifgfs_namer_063_500_vort_ht.gif

 

attachicon.gifgfs_namer_057_500_vort_ht.gif

 

analog packages don't take in to account whether a low is closed of vs open... its how many Standard Deviations at spot x and y and alignment of the height pattern (but mostly departures I think... someone with more info can chime in)...and those maps you posted to me do not scream rapid deepening/strong frontogenesis. Tonights run does.

 

ETA: They mostly say "moderate hit" to me

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Ian

Ian

Posted
Posted

analog packages don't take in to account whether a low is closed of vs open... its how many Standard Deviations at spot x and y and alignment of the height pattern (but mostly departures I think... someone with more info can chime in)...and those maps you posted to me do not scream rapid deepening/strong frontogenesis. Tonights run does.

ok. i'll disagree with your assessment but you make good pts. this may be a better run but your original comment was incorrect imo.

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Scarlet Pimpernel

Scarlet Pimpernel

Posted
Posted

Agree with the first bolded.  Regarding the second bolded, anyone who isn't just forecasting on a forum is looking seriously at it.  It's now not showing much that other models aren't save for low qpf.  At this point take from it what is helpful and leave the details to the mesoscale models..this system the devil is in the details, not something a lower res model will necessarily handle well within 24 h.

I'm not sure I'd even say it's much of an outlier per se.  Maybe a bit more east, but in terms of 500-mb and surface track it's pretty similar to others.  But the temperatures and precip are clearly far different.

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k94

k94

Posted
Posted

If you had to pick one model that has been pretty consistent with this system, beginning on FRIDAY (6 days out)...

 

I think it would have to be the UKMet.  Actually for a while, the UK and CMC were steady as she goes until the CMC went farther west with the SLP track 12Z today.

 

Include the EURO too, until what went down @12z today.

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dtk

dtk

Posted
Posted

So why are the precipitation maps so different for the NAM compared to the GFS?

I thought the NAM was skillful with modeling temperature as well as warm and cool convection.

Which model is more believable for this storm?

Neither?  To be honest, I'm not sure.  One certainly wouldn't normally want to rely on a coarser resolution model for a short range, dynamic forecast like this.  However, the GFS is generally decent guidance (with weaknesses and biases in certain regimes/regions/situations not being forgotten about) and I don't think it can simply be ignored.

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yoda

yoda

Posted
Posted

00z GGEM at 24 -- http://weather.gc.ca/data/model_forecast/528_100.gif

 

Snow moving into region... 1007mb L Big Bend of FL

 

36 --http://weather.gc.ca/data/model_forecast/530_100.gif

 

Heavy snow... 999mb L off SE NC coast by ~50 miles or so

 

48 -- http://weather.gc.ca/data/model_forecast/531_100.gif

 

Looks close to a capture... snow winding down... 982mb L just SW of 40/70 BM

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