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Forecast/storm discussions and part II Manitoba Mauler


Damage In Tolland
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The RGEM was too far east even initially-good snow really was never supposed to make it past Islip and it's now entering NYC and still going. To me the storm still looks very potent aloft and should at least slow significantly for a while. I'm becoming more cautiously optimistic that NYC shares in some of the high totals, as does W CT/MA. Maybe even NE NJ but the band's progress is really slowing now.

 

This is a theme I've been beating since Saturday... RGEM has an intense piece of vorticity far northeast of any other model, approximately near the Cape. At times in the past 2 days, this has resulted in a dual-low system (and GGEM did this too on Saturday). And I think it's now contributing to this further and faster northeast scoot.

 

May be totally wrong, but don't have access to Euro H5 to get a better sense of the responsible mechanics. 

 

The other mechanism that I keep beating: it's not just an eastward tick of a single SLP placement, I think it's also a northeast-stretch / dual-low-ish structure that is robbing some of the feed that would otherwise get pivoted west.

 

This actually may be the biggest fly in the ointment that the RGEM presents to the historic potential... and it's not on the EURO. Big difference. Something to watch for.

 

attachicon.gifrgem_precip_mslp_neng_4.png

 

You can see that eastern lobe clear as day on the water vapor, I have no doubt there's at least a kink under it.

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You can see that eastern lobe clear as day on the water vapor, I have no doubt there's at least a kink under it.

 

Clear on water vapor, but so far doesn't seem to have translated to an elongated or dual surface low:

 

 

Biggest Euro vs. RGEM difference in this regard occurs between 6z-9z when RGEM really develops a 2nd low way out, like 67W, whereas Euro collapses everything into one consolidated low. So as you and others have said, the evolution now to 4am will be critical.

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Why would NWS still be sticking to their guns on totals?

 

Lack of any clear and convincing reason to change for another few hours.

 

You can see wxniss found a good point there....The RGEM spins that up, and in the next 3-5 hours elongates the low NE from the benchmark.  It's at that moment the dynamics begin to whither a bit aside of some deformation banding. 

 

The GFS and NAM don't do this, nor does the 0z UKMET.  If we see the radar go to dogsh* from SW to NE the further west and south you guy starting about 1-2am aside of some bands....we'll know there's a potential issue. 

 

It should be clear as day in the next 1-2.5 hours.  We'd see a pretty marked decrease in intensity of even the banded snows off the NJ coast up through LI and into C W MA.  GFS/RGEM are not terribly dissimilar the GFS just doesn't bite on the elongated low.  NAM is on it's own right now.

 

Everything is wrapping up. Very marked increase in winds, very notable spin now to the radar.  Maybe a few gravity waves south?

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Clear on water vapor, but so far doesn't seem to have translated to an elongated or dual surface low:

 

attachicon.gifpres.ne-large_12am.png

 

Biggest Euro vs. RGEM difference in this regard occurs between 6z-9z when RGEM really develops a 2nd low way out, like 67W, whereas Euro collapses everything into one consolidated low. So as you and others have said, the evolution now to 4am will be critical.

 

GFS hints at it, but then collapses everything back again.  UKMET hints at it, collapses back too on the western edge. NAM never really bites at all.

 

Looking at the WV though...I do think wxniss we'll see a pulse down center to west for at least a few hours, as we wait for the rest of the energy to dive and for it all to stack.   We'll see what the radar shows in central/wMA,   CT, LI and sw in the next hour.

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GFS hints at it, but then collapses everything back again.  UKMET hints at it, collapses back too on the western edge. NAM never really bites at all.

 

Looking at the WV though...I do think wxniss we'll see a pulse down center to west for at least a few hours, as we wait for the rest of the energy to dive and for it all to stack.   We'll see what the radar shows in central/wMA,   CT, LI and sw in the next hour.

 

Nowcasting at its best, with relatively big stakes on the line.

Over next 2 hours, will be watching SLP, pressure fall rates, strength of the western CT / Long Island band and backfill of echos into NYC/NJ. And of course let's hope Euro can keep some respectable continuity right at showtime.

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Nowcasting at it's best, with relatively big stakes on the line.

Over next 2 hours, will be watching SLP, pressure fall rates, strength of the western CT / Long Island band and backfill of echos into NYC/NJ. And of course let's hope Euro can keep some respectable continuity right at showtime.

 

This sticks out to me  http://www.ndbc.noaa.gov/station_page.php?station=44008

 

I do think this lends some credibility to at least a temporarily extension.

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BTW 12z Euro had the same feature along the boundary...it just collapsed hardest and fastest to a position under ack. That can should flip hard east or SE S in the next few hours if those west tucks are valid.  If we see it staying E or ENE or NE....we very clearly know the low is staying further east.

 

Exactly, between 6z-9z is the difference. Euro quickly consolidates it into the main low near the benchmark, RGEM keeps the spoiler going through at least 12z.

 

Wish we had more rich pressure data. But as you said, we should see how this translates into the moisture feeding in over the next few hours.

 

Taking a quick break for pictures... will be back for Euro.

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Euro caves east...still much more impressive with the precip extent than the RGEM/GFS, but it def caved east.

 

I will stand by what I said, against itself this is one of the poorest performances I can remember for the Euro.  Luckily semi-predictable and I do think we're beginning to document a bias, JMHO.

 

If history is a guide the Euro is not done catching up. 

 

Wxniss I meant to post this on this thread...but the HRRR (not a fan) starts to come apart soon too.  This was the 3z total snow output.

 

ZCIizb0.png

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