March 25-26 Potential Bomb Part II

[rsteff]

It's not tucked in enough near the SE Coast early on so it escapes too far east.

Its 150 miles too far to the east  by the time its even with OBX

[earthlight]

The GFS was not that much improved, that's just my analysis as I get a glance at it for the first time today. The mid level ridge on the west coast was noticeably less amplified than the 12z run and that is the worst thing you could see. The ULL in the Northeast Pac being less organized and more progressive natured is the cause of this. We'll have to carefully monitor this on the models over the next few days. 

 

Meanwhile it did trend better with the phasing over the MS Valley and the mid level ridge axis ahead of the phasing shortwaves. So if we can get that to continue trending better, and see improvements out west, we could be talking. 

[user13]

The GFS was not that much improved, that's just my analysis as I get a glance at it for the first time today. The mid level ridge on the west coast was noticeably less amplified than the 12z run and that is the worst thing you could see. The ULL in the Northeast Pac being less organized and more progressive natured is the cause of this. We'll have to carefully monitor this on the models over the next few days. 

 

Meanwhile it did trend better with the phasing over the MS Valley and the mid level ridge axis ahead of the phasing shortwaves. So if we can get that to continue trending better, and see improvements out west, we could be talking. 

Yea i was surprised no one mentioned the ridge was weaker, we need the ridge to be sharper next run while still phasing earlier

[bluewave]

Its 150 miles too far to the east  by the time its even with OBX

 

It would be great if the PNA can come back to what the models were showing just a few days ago

so the vort can dig a little more while it's still far enough west to make a difference here. The ridge

north of Alaska got stronger with some slight corresponding weakness to the south over the

Canadian Rockies.

 

today

 

 

 

Wednesday

 

[Ed Lizard]

The DGEX is not just an extension of the NAM, IIRC.

 

It takes 12Z GFS initial conditons at hour 90 , feeds it to the equivalent of the NAM (I don't know which physics package, or how the difference in the GFS grid resolution gets fed as initial conditions to the NAM) and then runs a high res, long term version of the NAM, except I can't see how it isn't GIGO when it is fed model data at reduced resolution than what it runs at, and any errors in the 12Z GFS will tend to continue forward.

 

 

I could be wrong on some of this. 

[Ed Lizard]

Asked and not answered in previous thread, but mentioned again.  Could supposedly spurious convective feedback be actual convective feedback, thunderstorms near the edge of the Gulfstream intense enough to produce a warm core system within the larger baroclinic system?

 

It was showing up on models that usually have enough resolution not to develop spurious QPF bombs, like the Euro.

[bluewave]

The money quote from WPC:

 THE FACTTHAT PRIMARY SUPPORTING ENERGY ONLY REACHES NRN CANADA DURING THEWEEKEND AND MODELS SOMETIMES HAVE DIFFICULTY IN HANDLING FLOW FROMHIGH LATITUDES LEADS TO POTENTIAL FOR SOME CHANGES IN FUTUREGUIDANCE RUNS... THOUGH SHORT RANGE DETAILS OF THIS FLOW HAVEBECOME MORE AGREEABLE.  WEAK LEADING ENERGY INITIALLY OVER THENERN PAC AND STREAMING SEWD ACROSS THE CONUS MAY ALSO PLAY A PARTIN DEVELOPMENT.  AS IS THE CASE WITH MOST RAPIDLY DEEPENING STORMSTHERE WILL BE IMPORTANT SMALLER SCALE DETAILS THAT WILL NOT BERESOLVED UNTIL MUCH CLOSER TO THE EVENT

[PB GFI]

I have yet to see 1 model with a weak interpretation of the surface reflection off the EC. So part 1 is really seen in the atmosphere by the models

But it's placement is 100 miles outside the optimal point not 1000 miles away. WPC had a great piece this AM and alluded to this. How anyone looking at the numerical modeling and can be definitive today defies logic.

And pls stop fighting it cheapens the thread. By 12z tomorrow the models should have a little more to work with and a shift is coming.

I couldn't tell you if it's east or west. News flash. No one can.

Patience.

[user13]

 

The money quote from WPC:

 THE FACTTHAT PRIMARY SUPPORTING ENERGY ONLY REACHES NRN CANADA DURING THEWEEKEND AND MODELS SOMETIMES HAVE DIFFICULTY IN HANDLING FLOW FROMHIGH LATITUDES LEADS TO POTENTIAL FOR SOME CHANGES IN FUTUREGUIDANCE RUNS... THOUGH SHORT RANGE DETAILS OF THIS FLOW HAVEBECOME MORE AGREEABLE.  WEAK LEADING ENERGY INITIALLY OVER THENERN PAC AND STREAMING SEWD ACROSS THE CONUS MAY ALSO PLAY A PARTIN DEVELOPMENT.  AS IS THE CASE WITH MOST RAPIDLY DEEPENING STORMSTHERE WILL BE IMPORTANT SMALLER SCALE DETAILS THAT WILL NOT BERESOLVED UNTIL MUCH CLOSER TO THE EVENT

Good post by them...A good example of this was the Mesoscale low that developed with Feb storm over south Florida (that only the NAM actually had) which help bring that one a little more east.

[PB GFI]

The money quote from WPC:

THE FACT

THAT PRIMARY SUPPORTING ENERGY ONLY REACHES NRN CANADA DURING THE

WEEKEND AND MODELS SOMETIMES HAVE DIFFICULTY IN HANDLING FLOW FROM

HIGH LATITUDES LEADS TO POTENTIAL FOR SOME CHANGES IN FUTURE

GUIDANCE RUNS... THOUGH SHORT RANGE DETAILS OF THIS FLOW HAVE

BECOME MORE AGREEABLE. WEAK LEADING ENERGY INITIALLY OVER THE

NERN PAC AND STREAMING SEWD ACROSS THE CONUS MAY ALSO PLAY A PART

IN DEVELOPMENT. AS IS THE CASE WITH MOST RAPIDLY DEEPENING STORMS

THERE WILL BE IMPORTANT SMALLER SCALE DETAILS THAT WILL NOT BE

RESOLVED UNTIL MUCH CLOSER TO THE EVENT

LOL. I was typing as u posted this. Nice

[earthlight]

The fact that such definitive statements are being thrown around here 114 hours prior to the event is mind boggling to me, but I suppose fairly typical for weather forums. That being said, it doesn't take too much analysis of the mid level height fields to realize that the forecast models remain dangerously close to a significantly farther west solution and seem to want to continue teetering on the edge of this over the past 48 hours.

 

The GFS has a very robust jet streak surging southeastward through the Plains around 90 hours and there is a mid level shortwave associated with this feature which is visible on the 500mb vorticity maps. When you track the height field and orientation of this shortwave you can see the direct correlation it has in regard to the developing surface low. Additionally, you can see how the ridge axis to the west of this feature, owing to the placement and intensity of the upper level low in the Northeast Pacific, has huge implications on the positioning and amplitude of that said ridge. In black, I have highlighted the 18z GFS position of these features and in yellow, highlighted where they would need to be positioned to become more favorable/ideal for a farther west solution.

 

 

6-12 hours later, the models are in good agreement that a significant event will be unfolding somewhere from the Mississippi River Valley to the Southeast States, with a very energetic disturbance shifting east/southeastward and interacting with the lead shortwave. The incoming jet streak will aid in rapid amplification and development of mid level lows off the East Coast. However, the exact placement of the lead shortwave remains too far east -- and this is a direct result of interact between the incoming shortwave, positioning of the height field from the earlier frame pictured, and finally each individual model handling interactions and individual perturbations along the baroclinic zone. Once again, just slight adjustments will cause major changes and I have highlighted those accordingly.

 

 

With all of this noted, it is important to understand that forecast models are going to struggle immensely with each individual interaction as this system unfolds. We are currently entering a period where they should slowly start to get a better idea as to how the different players on the field will evolve. But it may not be until 48 hours prior to the event that all models will agree on how the small, finer interactions will occur.

 

I will say this -- we will know a lot more about how this is going to shake down once that lead piece of energy comes into a more dense observation area, and the models begin to get a better idea just how amplified the ridge will be on the west coast around that time. Until then, we can only do our best to analyze the pattern and trends (one run is not a trend, by the way) of global models and their ensembles.

[REDMK6GLI]

The fact that such definitive statements are being thrown around here 114 hours prior to the event is mind boggling to me, but I suppose fairly typical for weather forums. That being said, it doesn't take too much analysis of the mid level height fields to realize that the forecast models remain dangerously close to a significantly farther west solution and seem to want to continue teetering on the edge of this over the past 48 hours.

 

The GFS has a very robust jet streak surging southeastward through the Plains around 90 hours and there is a mid level shortwave associated with this feature which is visible on the 500mb vorticity maps. When you track the height field and orientation of this shortwave you can see the direct correlation it has in regard to the developing surface low. Additionally, you can see how the ridge axis to the west of this feature, owing to the placement and intensity of the upper level low in the Northeast Pacific, has huge implications on the positioning and amplitude of that said ridge. In black, I have highlighted the 18z GFS position of these features and in yellow, highlighted where they would need to be positioned to become more favorable/ideal for a farther west solution.

 

gfs1.png

 

6-12 hours later, the models are in good agreement that a significant event will be unfolding somewhere from the Mississippi River Valley to the Southeast States, with a very energetic disturbance shifting east/southeastward and interacting with the lead shortwave. The incoming jet streak will aid in rapid amplification and development of mid level lows off the East Coast. However, the exact placement of the lead shortwave remains too far east -- and this is a direct result of interact between the incoming shortwave, positioning of the height field from the earlier frame pictured, and finally each individual model handling interactions and individual perturbations along the baroclinic zone. Once again, just slight adjustments will cause major changes and I have highlighted those accordingly.

 

gfs2.png

 

With all of this noted, it is important to understand that forecast models are going to struggle immensely with each individual interaction as this system unfolds. We are currently entering a period where they should slowly start to get a better idea as to how the different players on the field will evolve. But it may not be until 48 hours prior to the event that all models will agree on how the small, finer interactions will occur.

 

I will say this -- we will know a lot more about how this is going to shake down once that lead piece of energy comes into a more dense observation area, and the models begin to get a better idea just how amplified the ridge will be on the west coast around that time. Until then, we can only do our best to analyze the pattern and trends (one run is not a trend, by the way) of global models and their ensembles.

as always john on point analysis and reasoning. that said im a firm believer that this storm will be the big one that has eluded us this year, although im not sure this would count towards the winter totals which would be a total let down

[REDMK6GLI]

 

The money quote from WPC:

 THE FACTTHAT PRIMARY SUPPORTING ENERGY ONLY REACHES NRN CANADA DURING THEWEEKEND AND MODELS SOMETIMES HAVE DIFFICULTY IN HANDLING FLOW FROMHIGH LATITUDES LEADS TO POTENTIAL FOR SOME CHANGES IN FUTUREGUIDANCE RUNS... THOUGH SHORT RANGE DETAILS OF THIS FLOW HAVEBECOME MORE AGREEABLE.  WEAK LEADING ENERGY INITIALLY OVER THENERN PAC AND STREAMING SEWD ACROSS THE CONUS MAY ALSO PLAY A PARTIN DEVELOPMENT.  AS IS THE CASE WITH MOST RAPIDLY DEEPENING STORMSTHERE WILL BE IMPORTANT SMALLER SCALE DETAILS THAT WILL NOT BERESOLVED UNTIL MUCH CLOSER TO THE EVENT

in short, everyone go out and enjoy your Friday night, things will get more interesting by 12z tomorrow.

[Blizzardo]

as always john on point analysis and reasoning. that said im a firm believer that this storm will be the big one that has eluded us this year, although im not sure this would count towards the winter totals which would be a total let down

It counts in my book! I dont care what anyone else says!

[PB GFI]

John , Lotta labor there. Great work

[jbenedet]

FWIW NAVGEM was much improved from its 12z run. Looks about 50 -75 miles further northwest at our latitude and about 10 mb stronger. Tracks approximately to the BM.

 

Upstream, H500 didn't look improved, in fact it looked slightly worse. The reason for the better track was the coastal forming further north and west, and deepening faster as well. Hence, the downstream ridge was able to amplify further. I find it somewhat encouraging to see these changes despite having no help from the upstream features this run.

[LongIslandWx]

as always john on point analysis and reasoning. that said im a firm believer that this storm will be the big one that has eluded us this year, although im not sure this would count towards the winter totals which would be a total let down

This storm would count towards the totals for the 2013-2014 winter season....which based on Upton's climate reports would be July 1st 2013 - June 30, 2014....although it's a bit confusing because they have lines for SINCE JUL 1 and SINCE OCT 1 in the total snowfall report.

[REDMK6GLI]

John , Lotta labor there. Great work

im sure he dug deep there for that statement. paul you've been quite the voice of reason as well

[tdp146]

The fact that such definitive statements are being thrown around here 114 hours prior to the event is mind boggling to me, but I suppose fairly typical for weather forums. That being said, it doesn't take too much analysis of the mid level height fields to realize that the forecast models remain dangerously close to a significantly farther west solution and seem to want to continue teetering on the edge of this over the past 48 hours.

The GFS has a very robust jet streak surging southeastward through the Plains around 90 hours and there is a mid level shortwave associated with this feature which is visible on the 500mb vorticity maps. When you track the height field and orientation of this shortwave you can see the direct correlation it has in regard to the developing surface low. Additionally, you can see how the ridge axis to the west of this feature, owing to the placement and intensity of the upper level low in the Northeast Pacific, has huge implications on the positioning and amplitude of that said ridge. In black, I have highlighted the 18z GFS position of these features and in yellow, highlighted where they would need to be positioned to become more favorable/ideal for a farther west solution.

gfs1.png

6-12 hours later, the models are in good agreement that a significant event will be unfolding somewhere from the Mississippi River Valley to the Southeast States, with a very energetic disturbance shifting east/southeastward and interacting with the lead shortwave. The incoming jet streak will aid in rapid amplification and development of mid level lows off the East Coast. However, the exact placement of the lead shortwave remains too far east -- and this is a direct result of interact between the incoming shortwave, positioning of the height field from the earlier frame pictured, and finally each individual model handling interactions and individual perturbations along the baroclinic zone. Once again, just slight adjustments will cause major changes and I have highlighted those accordingly.

gfs2.png

With all of this noted, it is important to understand that forecast models are going to struggle immensely with each individual interaction as this system unfolds. We are currently entering a period where they should slowly start to get a better idea as to how the different players on the field will evolve. But it may not be until 48 hours prior to the event that all models will agree on how the small, finer interactions will occur.

I will say this -- we will know a lot more about how this is going to shake down once that lead piece of energy comes into a more dense observation area, and the models begin to get a better idea just how amplified the ridge will be on the west coast around that time. Until then, we can only do our best to analyze the pattern and trends (one run is not a trend, by the way) of global models and their ensembles.

Thank you for posts like this.

[Edge Weather]

The fact that such definitive statements are being thrown around here 114 hours prior to the event is mind boggling to me, but I suppose fairly typical for weather forums. That being said, it doesn't take too much analysis of the mid level height fields to realize that the forecast models remain dangerously close to a significantly farther west solution and seem to want to continue teetering on the edge of this over the past 48 hours.

 

The GFS has a very robust jet streak surging southeastward through the Plains around 90 hours and there is a mid level shortwave associated with this feature which is visible on the 500mb vorticity maps. When you track the height field and orientation of this shortwave you can see the direct correlation it has in regard to the developing surface low. Additionally, you can see how the ridge axis to the west of this feature, owing to the placement and intensity of the upper level low in the Northeast Pacific, has huge implications on the positioning and amplitude of that said ridge. In black, I have highlighted the 18z GFS position of these features and in yellow, highlighted where they would need to be positioned to become more favorable/ideal for a farther west solution.

 

gfs1.png

 

6-12 hours later, the models are in good agreement that a significant event will be unfolding somewhere from the Mississippi River Valley to the Southeast States, with a very energetic disturbance shifting east/southeastward and interacting with the lead shortwave. The incoming jet streak will aid in rapid amplification and development of mid level lows off the East Coast. However, the exact placement of the lead shortwave remains too far east -- and this is a direct result of interact between the incoming shortwave, positioning of the height field from the earlier frame pictured, and finally each individual model handling interactions and individual perturbations along the baroclinic zone. Once again, just slight adjustments will cause major changes and I have highlighted those accordingly.

 

gfs2.png

 

With all of this noted, it is important to understand that forecast models are going to struggle immensely with each individual interaction as this system unfolds. We are currently entering a period where they should slowly start to get a better idea as to how the different players on the field will evolve. But it may not be until 48 hours prior to the event that all models will agree on how the small, finer interactions will occur.

 

I will say this -- we will know a lot more about how this is going to shake down once that lead piece of energy comes into a more dense observation area, and the models begin to get a better idea just how amplified the ridge will be on the west coast around that time. Until then, we can only do our best to analyze the pattern and trends (one run is not a trend, by the way) of global models and their ensembles.

 

Thank you John.  Very nicely done.  We all appreciate your hard work and analysis.

[Bluescat1]

Great write up John!

[famartin]

Asked and not answered in previous thread, but mentioned again.  Could supposedly spurious convective feedback be actual convective feedback, thunderstorms near the edge of the Gulfstream intense enough to produce a warm core system within the larger baroclinic system?

 

It was showing up on models that usually have enough resolution not to develop spurious QPF bombs, like the Euro.

 

This is from HPC, regarding what convective feedback actually is:

 

"When specific thresholds in the mass fields are met, the convective scheme is triggered and this dumps a large amount of QPF over a grid point - releasing so much latent heat over the grid point that the model is forced to adjust the mass fields by producing a local vertical motion max in the mid troposphere (~ 500mb), a corresponding upper level jet max over the vertical motion max - an intense and small scale vort max in the mid levels (MCV). The model scales up the mesoscale circulation at mid levels and holds onto it as a real feature for as long as 3 days. The model can produce precipitation in association with the feature as it tracks along in the flow."

 

These tend to be spurious especially when they happen in the cold sector, as the EC/GGEM depicted yesterday/last night. 

[Weathergun]

It would be great if the PNA can come back to what the models were showing just a few days ago

so the vort can dig a little more while it's still far enough west to make a difference here. The ridge

north of Alaska got stronger with some slight corresponding weakness to the south over the

Canadian Rockies.

 

today

 

gfs-ens_z500a_nhem_17.png

 

 

Wednesday

 

gfs-ens_z500a_nhem_25.png

 

Hate to say it. But there's been gradual daily trend to de-amplify the West Coast ridge on the ensembles.

 

250mb phased jet streaks off the coast, keep intensifying low well off the coast, as well. These trends need turn around for us:

 

 

[nyblizz44]

Thank you John.  Very nicely done.  We all appreciate your hard work and analysis.

U have no idea how much we appreciate it. Many Red taggers are great but this kind of effort & explanation goes a long way for amateurs who are genuinely interested in the journey as they are in the final product. Thank you sir!

[+SNfreak21]

Climo supports a track closer to the coast (3/29/84, 4/1/97)

[famartin]

Climo supports a track closer to the coast (3/29/84, 4/1/97)

2 events does not a climo make.  What you really need to do to establish "climo" is identify all coastal storms during a set period and track them.

[Juliancolton]

Climo supports a track closer to the coast (3/29/84, 4/1/97)

Heck of a sample size. I dunno, I'd rather have some respectable guidance on my side than a two-storm "climo"

[SnoSki14]

The lack of climo support just goes to show how anomalous the upcoming pattern really is.

[+SNfreak21]

Heck of a sample size. I dunno, I'd rather have some respectable guidance on my side than a two-storm "climo"

When was the last time we saw a Miller A with all snow to the coast at this time of the year? The MSLP and evolution reminds me of December 2010, where it bombed out to 972mb east of LI, and it relied on the amplification of the trough to force the surface low closer to us.

[SnoSki14]

We are going to have a snow bomb early next week, can't wait.