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Feb 27th threat - to be discussed in time, but it should tend to more Miller B

Typhoon Tip

By Typhoon Tip,
in New England

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weathafella

weathafella

Posted
Posted

We're cooked regardless.  But I hope places like WaWa can avoid most of the ML warming issues.  0z NAM would stink for them, even after a few inches.

Tis isn't about mby. I never had any reason to expect this was anything but wet. It should be a fun wet though as our rinds inland and elevated get smoked.

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wxmanmitch

wxmanmitch

Posted
Posted

As horrible as it is, the algorithms that try to apply orographic effects to QPE are nearly as bad.

 

I've found that the mesoscale models often overdo orographic effects in general in these parts with respect to upslope/downslope couplets. The finer the resolution, the more extreme the topographic effects are modeled to be.

 

On the other hand, more coarse models like the GFS often don't give it enough justice. There seems to be a happy medium grid resolution that will likely best simulate the orographic effects. I'm not sure what that is, but the 4 km and even 12 km meso models tend to overdo it. Based on the GFS having 0.5° (56 km) grid spacing, I'd have to guess it may be between 20 and 30 km. I'm not sure why this is, but it may have something to do with the non-hydrostatic nature of the meso models and the non-linearity of the atmospheric equations.

 

The reality is that midlevel precipitation processes will determine where the bulk of the QPF falls most of the time around here. Topography does play a role, but usually it's not as large as the finer resolution models make it out to be. There have been a lot of modeled upslope events that have not verified here. Up in N VT and N NH, on the other hand, topography will be much more important than it is here as the barriers are considerably larger.

 

In terms of this event, the low level temperatures will be critical as well, so it won't just be orographic uplift impacting the final outcome.

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radarman

radarman

Posted
Posted

I've found that the mesoscale models often overdo orographic effects in general in these parts with respect to upslope/downslope couplets. The finer the resolution, the more extreme the topographic effects are modeled to be.

 

On the other hand, more coarse models like the GFS often don't give it enough justice. There seems to be a happy medium grid resolution that will likely best simulate the orographic effects. I'm not sure what that is, but the 4 km and even 12 km meso models tend to overdo it. Based on the GFS having 0.5° (56 km) grid spacing, I'd have to guess it may be between 20 and 30 km. I'm not sure why this is, but it may have something to do with the non-hydrostatic nature of the meso models and the non-linearity of the atmospheric equations.

 

The reality is that midlevel precipitation processes will determine where the bulk of the QPF falls most of the time around here. Topography does play a role, but usually it's not as large as the finer resolution models make it out to be. There have been a lot of modeled upslope events that have not verified here. Up in N VT and N NH, on the other hand, topography will be much more important than it is here as the barriers are considerably larger.

 

In terms of this event, the low level temperatures will be critical as well, so it won't just be orographic uplift impacting the final outcome.

 

Excellent post as usual Mitch.  

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weatherMA

weatherMA

Posted
Posted

I've found that the mesoscale models often overdo orographic effects in general in these parts with respect to upslope/downslope couplets. The finer the resolution, the more extreme the topographic effects are modeled to be.

 

On the other hand, more coarse models like the GFS often don't give it enough justice. There seems to be a happy medium grid resolution that will likely best simulate the orographic effects. I'm not sure what that is, but the 4 km and even 12 km meso models tend to overdo it. Based on the GFS having 0.5° (56 km) grid spacing, I'd have to guess it may be between 20 and 30 km. I'm not sure why this is, but it may have something to do with the non-hydrostatic nature of the meso models and the non-linearity of the atmospheric equations.

 

The reality is that midlevel precipitation processes will determine where the bulk of the QPF falls most of the time around here. Topography does play a role, but usually it's not as large as the finer resolution models make it out to be. There have been a lot of modeled upslope events that have not verified here. Up in N VT and N NH, on the other hand, topography will be much more important than it is here as the barriers are considerably larger.

 

In terms of this event, the low level temperatures will be critical as well, so it won't just be orographic uplift impacting the final outcome.

Interesting, thanks for your insight! 

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N. OF PIKE

N. OF PIKE

Posted
Posted

Do we really have much faith in anything but the euro/euro ens? At this point, what other model gives u confidence but the euro! Sprinkle in a bit of meso's for enhancement areas and downslope areas,take into account potentially a tad better cad, and walla lol. I dunno, but we get the point wrt euro being only model worth trusting

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free_man

free_man

Posted
Posted

if you understand a models biases, nuances and so forth,  there is no faith in models... only faith in interpretation.

Do we really have much faith in anything but the euro/euro ens? At this point, what other model gives u confidence but the euro! Sprinkle in a bit of meso's for enhancement areas and downslope areas,take into account potentially a tad better cad, and walla lol. I dunno, but we get the point wrt euro being only model worth trusting

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Quincy

Quincy

Posted
Posted

RGEM is nothing to write home about. Euro and whatever supports it generally ( but not always).

RGEM is warm tonight.

We don't like the RGEM? I've always liked to lean on it for short-term, tends to be a lot more realistic than some weenie NAM solutions.
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