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September 17-19 2012 rain and severe weather potential


SNO

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The strong jet at 925mb (50-60+ kts depending on the model you look at) is good for damaging wind potential... even weak convection can mix (or bring down) those kind of wind speeds to the surface.

Having a bit of an easterly component to the winds (out of the southeast instead of south or southwest) not only adds more spin to the low-levels of the atmosphere, but it will also help these storms ingest more unstable air and allow storms to have a longer lifespan.

Of course, such high winds throughout the column suggest storms will also be moving pretty quickly... mature storms will have a forward speed of 50-60 mph... perhaps faster in some cases.

The only risk that could corrupt a setup like this is a lack of instability, without at least a marginally buoyant atmosphere you run the risk of the updrafts being sheared apart. A circumstance of having potentially too much shear.

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The strong jet at 925mb (50-60+ kts depending on the model you look at) is good for damaging wind potential... even weak convection can mix those kind of wind speeds to the surface.

Having a bit of an easterly component to the winds (out of the southeast instead of south or southwest) not only adds more spin to the low-levels of the atmosphere, but it will also help these storms ingest more unstable air and allow storms to have a longer lifespan.

Of course, such high winds throughout the column suggest storms will also be moving pretty quickly... mature storms will have a forward speed of 50-60 mph... perhaps faster in some cases.

Thanks, not all of us understand the nerd speak ;)

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Depends on what kind of storm you're trying to get and where the unstable air is, but generally the answer is yes.

I'd like a Snownado. What types of winds do we need to get one of those?

A more serious question, is this event morphing into more of a squall-line t-storm event, or is that just when the front slices through?

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The strong jet at 925mb (50-60+ kts depending on the model you look at) is good for damaging wind potential... even weak convection can mix those kind of wind speeds to the surface.

Having a bit of an easterly component to the winds (out of the southeast instead of south or southwest) not only adds more spin to the low-levels of the atmosphere, but it will also help these storms ingest more unstable air and allow storms to have a longer lifespan.

Of course, such high winds throughout the column suggest storms will also be moving pretty quickly... mature storms will have a forward speed of 50-60 mph... perhaps faster in some cases.

Didn't intend to step on toes if you perceived it as such.

I like to think I'm pretty decent at decoding some concepts

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I don't like what I'm seeing on the progs. Unlike many here, I don't much like systems that have a high probability of causing power outages across portions of the region. Fast moving storms usually have some of the storms with strong enough downdrafts to bring strong winds down to the surface. The sounding shows strong winds not far from the surface making it likely some cell will deliver strong winds which will bring down limbs and trees. Hopefully, not in my yard. Living in home surrounded by trees, that's not something I like very much.

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Agreed...not a fan of wind events. This will end up being a decent rainmaker. The idea that early storms lay the foundation of storm tracks later does not bode well for the MA in terms of snow, IMHO. The track would be to our West and put us in line for more rain than frozen precp, with cold front rushing in behind changing to a little backend snow, which we all know does not usually work out well for us.

Safe driving all tommorow.

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Will be interesting to see if 12z GFS follows suit... doesn't the NAM overdo CAPE in these types of environments? 1730 SPC OTLK should be an interesting read

Not based on what I've seen. It normally overdoes CAPE when we get a downsloping event... NAM will usually keep winds out of the south more ahead of a cold front, keeping dewpoints and CAPE higher than other models like the GFS, which will more correctly depict the westerly component of the wind and associated downslope mixing. Both models are showing winds out of the south/SSE at the surface for this event, so I'd trust the NAM more this time around.

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Not based on what I've seen. It normally overdoes CAPE when we get a downsloping event... NAM will usually keep winds out of the south more ahead of a cold front, keeping dewpoints and CAPE higher than other models like the GFS, which will more correctly depict the westerly component of the wind and associated downslope mixing. Both models are showing winds out of the south/SSE at the surface for this event, so I'd trust the NAM more this time around.

Appreciate the response Ellinwood. Always looking for biases from the models ;)

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I don't like what I'm seeing on the progs. Unlike many here, I don't much like systems that have a high probability of causing power outages across portions of the region. Fast moving storms usually have some of the storms with strong enough downdrafts to bring strong winds down to the surface. The sounding shows strong winds not far from the surface making it likely some cell will deliver strong winds which will bring down limbs and trees. Hopefully, not in my yard. Living in home surrounded by trees, that's not something I like very much.

I agree about the high wind and power outages. I dont like systems that bring those around my area either. I also live where lots of trees can come down on our home which makes these storms worrisome.

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Agreed...not a fan of wind events. This will end up being a decent rainmaker. The idea that early storms lay the foundation of storm tracks later does not bode well for the MA in terms of snow, IMHO. The track would be to our West and put us in line for more rain than frozen precp, with cold front rushing in behind changing to a little backend snow, which we all know does not usually work out well for us.

Safe driving all tommorow.

No snow this winter.

:cry:

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