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06z Model Thread


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700 mb rh at 24 suggests alot of dry air on western flank. 30 probably wont look very good, atleast in VA. Looks like everything is more positive tilt than the GFS, albeit alittle furth west. Maybe slower?

surface low also looks strung out again

the RH field given the slightly better 850 setup still looks funky to me.

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NAM is keeping the best PVA to the northeast...which is why the sfc low follows. It's not closing off that 5h low and ripping the vorticity back to the N and NW as fast as other runs...the sfc low loves where PVA (positive vorticity advection)...and in this case its a big deal because the vort max is so strong after it rounds the base.

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NAM is having major issues during the formative stages of cyclogenesis. Its having issues with the handoff of energy during the phase and just looks a little off. I suppose it is possible that there will be issues and not a "smooth" transition as the low starts to get going but more likely the NAM is having some kind of issues here. It just looks wrong. Has a really nice band of precip initially and then just loses it as it tries to get the coastal going. Redevelops everything later but OTS for the mid atlantic. Weird run again.

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NAM is keeping the best PVA to the northeast...which is why the sfc low follows. It's not closing off that 5h low and ripping the vorticity back to the N and NW as fast as other runs...the sfc low loves where PVA (positive vorticity advection)...and in this case its a big deal because the vort max is so strong after it rounds the base.

Yeah, it also appears to have a lot of noise vorticity out ahead of the vortmax that appears to be aiding in the elongated look perhaps?

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NAM is having major issues during the formative stages of cyclogenesis. Its having issues with the handoff of energy during the phase and just looks a little off. I suppose it is possible that there will be issues and not a "smooth" transition as the low starts to get going but more likely the NAM is having some kind of issues here. It just looks wrong. Has a really nice band of precip initially and then just loses it as it tries to get the coastal going. Redevelops everything later but OTS for the mid atlantic. Weird run again.

So you'd go with a consensus of GFS and EURO over the NAM at this stage?

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Yeah, it also appears to have a lot of noise vorticity out ahead of the vortmax that appears to be aiding in the elongated look perhaps?

There's always worry about "noise" witht he NAM. Who knows if its right or not, but you have to get that PVA back further NW than what it's showing to get the sfc low and dynamics for qpf (which is all anyone cares about no matter what the sfc low does) back into those regions of the Mid-Atlantic.

The forecast to me in the Mid-Atlantic is about as hard as it gets because I could see them getting a huge storm also not getting much more than some light snow. I think once up to NYC area and northeastward is a bit safer but that is assuming this current suite of models is right. The models have been having all sorts of problems with this setup if it wasn't already obvious.

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NAM is keeping the best PVA to the northeast...which is why the sfc low follows. It's not closing off that 5h low and ripping the vorticity back to the N and NW as fast as other runs...the sfc low loves where PVA (positive vorticity advection)...and in this case its a big deal because the vort max is so strong after it rounds the base.

correct me if Im wrong but if you remove that stupid feedback error wouldn't the low (approximately where I have the Red L) be closer to where I have the black L. I don't know how many times I've seen that feedback error of too much vorticity escaping... what causes that anyway?

post-3403-0-94291900-1293265534.png

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correct me if Im wrong but if you remove that stupid feedback error wouldn't the low (approximately where I have the Red L) be closer to where I have the black L. I don't know how many times I've seen that feedback error of too much vorticity escaping... what causes that anyway?

post-3403-0-94291900-1293265534.png

No the best PVA will be well northeast of where you have it...its not just PVA either...thats where the best lift is in the mid-levels...but the sfc low is usually not horribly far off there...the sfc low wants the best area of upper level divergence and WAA. That will be well northeast of where your black low is and closer where the red low is.

The NAM is correct where the low is based on 5h...but the question is whether 5h is right...which it might not be.

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