blizzard of 2013 discussion

[earthlight]

For those asking about the RGEM..it is much colder than 00z during the most important part of the system.

 

http://meteocentre.com/models/gemreg_amer_qc_12/PT_PN_009_0000.gif

[dtk]

I only follow the GFS on tuesdays when i need the weather from monday. A lil humor. It has been so bad with these southerm branch features over the past 15 years i just wish someone would b honest and say we dont hav the money to input constant real time data like euro. Instead of just 4x a day Pls correct if wrong or our resolution isnt as good. Image havin to b a private forecaster in boston ths past wk and the euro paints u a pic of a bomb and u look to ur mighty US tool and its sending the slp to bremuda. It misses these big time systems over and over again. Sandy was just embarrasing. But so were 5 blizzards 3 days out that i can think of off the top of my head

You guys hav to see the errors. Whats the consensus on the fix.

 

Don't have money to input constant real time data like the euro?  What are you talking about?  The 4x/day isn't just about the GFS, but also for providing initial and our boundary conditions for many other models.  It does not miss "big time systems" over and over again, this is largely a myth.  Sandy was not an "embarrassment", give me a break. 

 

Is the ECWMF (on average) better?  yes, statistics bear that out.  Is it always better?  uhm, no. 

 

Yes, they have a much larger supercomputer, have a much smaller scope (ECMWF only does global modeling for medium range and seasonal prediction), which allows them do things that are much more computationally intensive.  Do you have any idea how diverse the NCEP production suite is?  The fact that we can even compete with them some of the time is pretty remarkable considering the resource discrepancy.

 

Reading garbage like this is exhausting, and makes me want to come back to this board a little less each day.  Congratulations.

[sferic]

Intellicast seems to show the blues sliding south back through LI sound, is this right?

http://www.intellicast.com/National/Radar/Current.aspx?animate=true

[earthlight]

The 12z RGEM is about 50-75 miles farther northwest with the southern stream vort valid at at 2100z Friday when compared to the 00z run from last night. These types of small changes can make a huge difference in sensible weather when you're dealing with an intricate phase like this. See for yourself:

 

12z run: http://meteocentre.com/models/gemreg_amer_qc_12/QQ_GZ_UU_VV_009_0500.gif

 

00z run: http://meteocentre.com/models/gemreg_amer_qc_00/QQ_GZ_UU_VV_021_0500.gif

[RCNYILWX]

if this is what we're looking at come late tonight into early am, many weenies will be smiling 

 

http://cimss.ssec.wisc.edu/goes_r/proving-ground/nssl_abi/ani_js/abi_band11.html

One thing that hasn't been written about but I think is important to keep in mind is that the models are notorious for doing is developing too much precipitation right near the dry slot of an intense mid latitude cyclone. The heaviest precipitation typically occurs 50-100 miles northwest of the dry intrusion, which can be seen well on this W/V simulation. If the simulation ends up close to what occurs, it shows that there may be dry slotting issues for a time into far eastern LI and up to far southeastern New England, with central IL and points west and north spending several hours in the comma head of the cyclone. This would indicate very heavy snowfall rates given the dynamics of the system, with the limiting factor being just how long those heavy snowfall rates last before the system pivots off to the east. So I'd say we're still in good shape once changeover back to all snow occurs in NYC out to central LI for at least 6-9 hours of heavy snow.

[jm1220]

I don't have JFK right now (got LGA from a different source).

 

There definitely was a bit of a warm tongue in parts of LI on the mm5 verbatim, though, but if you look at the graphic that earthlight just posted, it shows a warm tongue in Nassau and Western Suffolk, yet 100% probability of frozen precipitation in the Twin Forks of LI...intuition would tell me that if there is a 100% probability of frozen precipitation on the Twin Forks, then there shouldn't be such a strong warm tongue in Nassau and Western Suffolk. 

Doesn't make a lot of sense to me-what mechanism could cause that? If we get into the deeper lift I would think whatever warmth would be overcome.

[IsentropicLift]

The 12km also picking up on the warm tongue as well. I hope this doesn't happen, totals will be significantly lower. 

Correct me if I'm wrong, didn't the 18z NAM and 00z NAM last night snow much more accumulations over the city and points NW and less over central Long Island? Sort of dry slotted them a bit based off of simulated radar. I wonder if this "warm tongue" has anything to do with it?

[ace0927]

But the 12z run is much, much wetter, and I just posted a skew-T for LGA that looked great at 20z! That's really early. We should probably change over by 21z, IMO. 

BTW - go look at that sjew t's from the MM5 from 0Z...this set is significantly warmer.

[WintersGrasp]

I have a question for a met...earth light maybe ? It is clearly depicted on the models that the much heavier banding will be focused into CT and MA right around Boston, NOT over NJ/NYC...the mm5, NAM, etc all show this....now....in realizing that...what do you think we are looking at once IN the banding ? Maybe 1" up to 2" per hour in NYC area's band and 3-5" per hour in Boston's banding ? For example, the GFS shows more QPF over Boston anyway, but aside from that, sim radars and indications of where the bands will be on the other models still show Boston under the heavier banding, which does not always fall in line 100% with the QPF totals

[IsentropicLift]

One thing that hasn't been written about but I think is important to keep in mind is that the models are notorious for doing is developing too much precipitation right near the dry slot of an intense mid latitude cyclone. The heaviest precipitation typically occurs 50-100 miles northwest of the dry intrusion, which can be seen well on this W/V simulation. If the simulation ends up close to what occurs, it shows that there may be dry slotting issues for a time into far eastern LI and up to far southeastern New England, with central IL and points west and north spending several hours in the comma head of the cyclone. This would indicate very heavy snowfall rates given the dynamics of the system, with the limiting factor being just how long those heavy snowfall rates last before the system pivots off to the east. So I'd say we're still in good shape once changeover back to all snow occurs in NYC out to central LI for at least 6-9 hours of heavy snow.

More like what the 00z NAM showed correct?

 

[uncle W]

starting to hear some pinging on the window...sleet has started to mix in with the rain...

[Dsnowx53]

Doesn't make a lot of sense to me-what mechanism could cause that? If we get into the deeper lift I would think whatever warmth would be overcome.

 

 

Yeah, I honestly don't know. Maybe some back bending warm front or something? But to me, it doesn't make sense given that the Twin Forks are under 100% probability of frozen precip at 00z, and are not under heavier banding at that time. Even the NAM has us changing over earlier than that, so I'll believe that seemingly random warm tongue when I see it, to be honest. 

[TWCCraig]

Correct me if I'm wrong, didn't the 18z NAM and 00z NAM last night snow much more accumulations over the city and points NW and less over central Long Island? Sort of dry slotted them a bit based off of simulated radar. I wonder if this "warm tongue" has anything to do with it?

 

Yea it did, NAM still gave us 18"-24". Not that we were dry slotted, but the CCB set up better over you guys. Now it's us back under the CCB, but the warm tongue is there, it that happens, going to be a very heavy rain.

[jm1220]

BTW - go look at that sjew t's from the MM5 from 0Z...this set is significantly warmer.

You really need a timeout. Seriously.

[IsentropicLift]

For those asking about the RGEM..it is much colder than 00z during the most important part of the system.

 

http://meteocentre.com/models/gemreg_amer_qc_12/PT_PN_009_0000.gif

Really glad to see that move NW, that was really sticking like a thorn in my side because I know it's a very reliable short term model.

[dbc]

BTW - go look at that sjew t's from the MM5 from 0Z...this set is significantly warmer.

True but not enough to damage snow totals, in fact it is wetter thus snowier because the warmth is not enough to not be snow. Further away from the warm intrusion will see high ratios too 12-15:1 easy.

[LongIslandWx]

I don't have JFK right now (got LGA from a different source).

 

There definitely was a bit of a warm tongue in parts of LI on the mm5 verbatim, though, but if you look at the graphic that earthlight just posted, it shows a warm tongue in Nassau and Western Suffolk, yet 100% probability of frozen precipitation in the Twin Forks of LI...intuition would tell me that if there is a 100% probability of frozen precipitation on the Twin Forks, then there shouldn't be such a strong warm tongue in Nassau and Western Suffolk. 

 

During one of the storms of the 2010 - 2011 season (I forget the date), there was a warm tongue that was persistent over SWern CT.  It was raining in Greenwich when I left work, but snowing in Bellerose when I got home.  That warm tongue collapsed overnight and they got heavy snow as well.  Sometimes weird things show up.  Saw in the obs a poster from Rocky Point reporting snow, but it's all rain in Nassau.

[Dsnowx53]

The UKIE finally came west, as well. 

[mulen]

Started out gangbusters hopefully ma nature just playing with us temp just dropped to 34  **** rain. I was at the seawall by the throgs nk bridge this morning when the wind shifted ene. I chartered fished the western sound 25yrs i have my 6 pack this storm is challenging for our area.The wind is a big part of this event if nothing else i'll be glad with whatever we get last year at this time i was pissing on sparkplugs for a few flakes.Patience you what the difference is between a hunter and a fishermen is a hunter lies in wait and a fisherman waits and lies.see ya

[RCNYILWX]

More like what the 00z NAM showed correct?

Not necessarily, I was really just trying to point out that there's been a lot of hand-wringing over changes in the exact qpf amounts given by the models and assumptions on what that means for snow totals in backyards. The one thing the models do worst is forecast qpf, even in the short range, they can be useful suggestions of what may occur but looking at mid and upper level moisture fields collocated with strongest forcing for upward motion can give you a better idea of where the heaviest precip will occur. 

[FPizz]

^{So far we haven't lost too much to the mix/rain it seems.  I haven't really seem moderate anything for more than a few minutes here and there.}

 

^{btw: Just changed back to mostly snow in the bedminster area after about 20 minutes of sleet}

[Ed Lizard]

Curious- any NWS/NCEP types have access to ACARS from around the Tri-State? (Automatically recorded aircraft data, some airlines share data with NWS on condition it isn't made public.  HGX, which doesn't have the luxury of balloons, refers to ACARS in AFDs all the time when forecasting whether the cap will break in potential severe weather situations).  If so, which of the available 12Z guidance seems to best fit temp profiles above the NYC area?

[MJO812]

12z Ukie came west from 0z.

 

http://weather.uwyo.edu/cgi-bin/model?MODEL=ukmet&TIME=2013020812&REGION=USLCC&FCST=all&LEVEL=500&F2=none&C1=hght&C2=tmpc&VEC=none&F1=p06i

 

It has  nice band later tonight for the NYC area, especially LI.

[Shades]

On the warm tongue depicted by the MM5 for central Nassau this evening... maybe it's not a warm tongue per se but a lack of precipitation (since the map is a forecast for the probability of precip/afterall), could be subsidence between banding.. although hard to believe it would go entirely dry. Lighter precip would also suggest less dynamic cooling between bands. We've seen this before, where one area is thumping snow, and a few miles away, light rain.

[Dsnowx53]

During one of the storms of the 2010 - 2011 season (I forget the date), there was a warm tongue that was persistent over SWern CT.  It was raining in Greenwich when I left work, but snowing in Bellerose when I got home.  That warm tongue collapsed overnight and they got heavy snow as well.  Sometimes weird things show up.  Saw in the obs a poster from Rocky Point reporting snow, but it's all rain in Nassau.

 

 

Thanks for the info. I wonder what caused that warm tongue. My first guess was that it would have been the 2/26/10 storm, but you mentioned it was the 2010-2011 season, so I'm not sure. 

[Brian5671]

During one of the storms of the 2010 - 2011 season (I forget the date), there was a warm tongue that was persistent over SWern CT.  It was raining in Greenwich when I left work, but snowing in Bellerose when I got home.  That warm tongue collapsed overnight and they got heavy snow as well.  Sometimes weird things show up.  Saw in the obs a poster from Rocky Point reporting snow, but it's all rain in Nassau.

that was the 1/27/11 storm.  I remember it well-sleet mixed in for much longer than it should have...

[TWCCraig]

On the warm tongue depicted by the MM5 for central Nassau this evening... maybe it's not a warm tongue per se but a lack of precipitation (since the map is a forecast for the probability of precip/afterall), could be subsidence between banding.. although hard to believe it would go entirely dry. Lighter precip would also suggest less dynamic cooling between bands. We've seen this before, where one area is thumping snow, and a few miles away, light rain.

 

On the NAM, it has heavy precip in the warm tongue. Doesn't make sense.

[NorthNJwx]

~25 miles NNW of Central Park, here, and 32.0 degrees with steady snow. The temp got up to 32.4 earlier, and has been falling since. No mixing at all, as expected. I'd imagine temps will be falling to my SE as well sooner than later. 

[jdt]

Yes that can make all the difference in the world when you are currently sitting on the edge of a generic 5-10" type snowstorm and a major 12-18" or greater storm. Some hearts will sore and some will be broken later this evening. Of course our pre determined expectations usually have much more to do with that than the actual meteorlogical outcome.

The 12z RGEM is about 50-75 miles farther northwest with the southern stream vort valid at at 2100z Friday when compared to the 00z run from last night. These types of small changes can make a huge difference in sensible weather when you're dealing with an intricate phase like this. See for yourself:

 

12z run: http://meteocentre.com/models/gemreg_amer_qc_12/QQ_GZ_UU_VV_009_0500.gif

 

00z run: http://meteocentre.com/models/gemreg_amer_qc_00/QQ_GZ_UU_VV_021_0500.gif

[forkyfork]

time for a new thread