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2/19 East Coast Winter Storm Threat


OKpowdah

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The last 24 hours of model runs have certainly had a few interesting outcomes / trends.

A number of factors here that need to be considered for this forecast problem.

1) The Friday trough ... amplitude, speed, etc. ... that is our "50/50" low

2) Shortwave diving through the Midwest around the same general vortex on Saturday morning 2/18

... some model runs actually keyed in on this s/w to phase (or attempt phasing) with the southern energy

3) More s/w energy in Manitoba within the west side of the vortex that may or may not amplify into a lobe off the vortex.

... this is where the vortex gets stretched, which is a decent idea considering upper level flow on the south side of the vortex accelerates from ~40kt over the Midwest to 150kt+ blasting off the east coast.

4) The southern energy ...amplitude, speed, etc. ... pretty classic Gulf coast low in formation on all the model guidance.

5) Shortwave in the Central Plains Saturday morning

... this has generally been the "popular choice" for the models at this point for the key northern s/w.

6) Shortwave upstream of (5) in southern Canada

... I think a few runs this weekend wanted to key in on this one, but that idea has flown. Now the Euro wants to phase it into the western vortex energy (3)...

7) Another pesky s/w coming onshore in the west kicking things eastward, and preventing an amplified western ridge.

post-128-0-59496900-1329162273.png

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We should get 2 and 6 to party with 4 and 5.

:lol:

I'm thinking 3 and 6 with 4 and 5. Shear 2 out of the picture into the forming vort lobe centered around 1

But yeah, the interactions between all these disturbances are sure to provide a number of different solutions over the next 5 days.

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:lol:

I'm thinking 3 and 6 with 4 and 5. Shear 2 out of the picture into the forming vort lobe centered around 1

But yeah, the interactions between all these disturbances are sure to provide a number of different solutions over the next 5 days.

Haha, yeah that's what I meant. What a weenie convo..lol.

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oh, okay, there is a thread then - I posted on this next system in that other thread.

NCEP was all over this system. It's uncertian how much N- stream phasing there will be... What is interesting about that, much of that will actually be determined by the amount of S/W potency riding underneath the SPV dangling in wait up over Ontario... These subsume scenarios take place because the SPVs in question were essentially held in check by the geopotential medium riding out at lower latitudes... But when the S/W incurs a weakness in that field south, such as drilling a stronger S -stream impulse through, down she comes...

This is best illustrated by Feb 1978, and that debacle MA ghost storm of all ages, March 2001. These are both classic subsume scenarios, where southern stream really induced the SPV out of its den - "dont' wake the sleeping bear" - so to speak.

There are some appeals about this - the 12z Euro in particular was darn close. You could see at 144 hours the N -stream just wants to ...it's begging to, but doesn't make the switch. The UKMET is has yet a strong southern stream system, but it lacks the N -stream SPV material and ops for an open tripple wave look. Kind of weird... The GFS has been persistently lacking any S -stream potency and going with all N -steam. The GFS is just an open N -stream wave with not much S -stream to work with ...a little though.

With that much variety in depicted stream interaction, ouch

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Yeah, Better then the op, With all the pieces involved we are going to see a variety of solutions for a few more days

I was just going to post that... wow... There has to be a couple of MECS's in the individual members there...Its interesting Scott, the GFS op completely vanishes the Southern Vort on the 18z run. It was pretty potent too...

18zgfsensemblep12144.gif

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WOW! Does anyone have individual members for the GFS ensemble yet?

The southern energy is much more amplified in the MEAN than on the op, and just looking at the smoothed mean heights, I would guess a few members at least come close to dropping the PV lobe into the trough and produce something big.

Wow, great to see this on the ensembles

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It might be the GFS loving to crush srn stream energy. That's why you have ensembles, they are a lot better than the op at day 6.

Anyways, having the 18z GEFS on board at day 6 is not exactly comforting, but I think the threat has some legs for now. Tonight's guidance should be interesting, but I wouldn't expect massive jumps.

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It might be the GFS loving to crush srn stream energy. That's why you have ensembles, they are a lot better than the op at day 6.

Anyways, having the 18z GEFS on board at day 6 is not exactly comforting, but I think the threat has some legs for now. Tonight's guidance should be interesting, but I wouldn't expect massive jumps.

This probabaly deserves a weenie but sometimes the 18z GFS can be the first to sniff out some of these large scale threats.......... :lol:

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