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MaineJayhawk

NNE Autumn 2013 Thread

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Welcome to November in Vermont...endless clouds, northwest flow, and foggy mountain tops. Oh wait its SEPTEMBER wtf. :axe:

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Welcome to November in Vermont...endless clouds, northwest flow, and foggy mountain tops. Oh wait its SEPTEMBER wtf. :axe:

 

LOL yeah my NWS forecast went from clear each day to clouds through Thursday night.

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Welcome to November in Vermont...endless clouds, northwest flow, and foggy mountain tops. Oh wait its SEPTEMBER wtf. :axe:

 

We have cleared out here on the east side... beautiful afternoon on the way over here, lol.

 

It looks like blocked flow but Froude Number is showing 1.3... but its got that moisture stuck below the inversion which is at or below the summit level type of look to the satellite image.

 

1,500ft at the base of Stowe is in the sun (though the upper lift terminals are ending in the clouds)...

 

 

And the western slope communities are still under the low overcast, blocked by the mountains.

 

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We have cleared out here on the east side... beautiful afternoon on the way over here, lol.

 

It looks like blocked flow but Froude Number is showing 1.3... but its got that moisture stuck below the inversion which is at or below the summit level type of look to the satellite image.

 

1,500ft at the base of Stowe is in the sun (though the upper lift terminals are ending in the clouds)...

 

attachicon.gifwebcam.jpg

 

And the western slope communities are still under the low overcast, blocked by the mountains.

 

attachicon.gifwestslope.jpg

We were blocked all morning (Froude was anywhere from 0.25-0.75 last night and this morning), but then just on the latest ob it jumped up to 1.3, and that is actually quite evident in the observations and satellite pictures. We just broke out here in BTV.

 

VIS when we were still blocked, that blocked upslope enhancement is really noticeable:

16h22kj.png

 

VIS now unblocked, you can see the upslope enhancement melting away:

 

2irxh6p.jpg

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We have cleared out here on the east side... beautiful afternoon on the way over here, lol.

 

It looks like blocked flow but Froude Number is showing 1.3... but its got that moisture stuck below the inversion which is at or below the summit level type of look to the satellite image.

 

1,500ft at the base of Stowe is in the sun (though the upper lift terminals are ending in the clouds)...

 

attachicon.gifwebcam.jpg

 

And the western slope communities are still under the low overcast, blocked by the mountains.

 

attachicon.gifwestslope.jpg

PF, do you know what kind of cams those are on the buildings?

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WOw already rimed over good up there! As for here in the CPV it is turning out to be a beautiful afternoon. We are just about at full sun now.

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Since we are thinking about winter this was my last good winter weather capture in NC before moving up here:

 

 

Wow, that was pretty darn loud.

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Wow, that was pretty darn loud.

 

It definitely was! It was a vigorous upper level disturbance.

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It definitely was! It was a vigorous upper level disturbance.

 

I think I remember that as well. Was it rather squally in nature? It wasn't from some sort of deformation band, correct?

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By the way we will have to see what this coastal/tropical system being shown in some models does next week.

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I think I remember that as well. Was it rather squally in nature? It wasn't from some sort of deformation band, correct?

 

Yes it definitely was and yes there were deformation snows.

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PF, do you know what kind of cams those are on the buildings?

 

Not first hand but I can find out for you... I actually think the Stowe cam is or was Tim Kelley's at some point.  Don't ask me how or why, haha.

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We were blocked all morning (Froude was anywhere from 0.25-0.75 last night and this morning), but then just on the latest ob it jumped up to 1.3, and that is actually quite evident in the observations and satellite pictures. We just broke out here in BTV.

 

VIS now unblocked, you can see the upslope enhancement melting away:

 

 

Ahh that makes sense. 

 

As soon as the Froude values jumped up this morning, the clouds thinned out quickly but the clouds that remained, rose a few thousand feet and then centered themselves over the Spine.... consistent with 1< Froude Numbers.  Earlier this morning, these clouds were lower down and left of the peaks.

 

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Clouds are increasing here once again. They are wave clouds at the mid levels.

I was out running when they moved in...pretty awesome waves in the atmosphere with the lowering sun only illuminating the lowest parts. They don't seem overly thick, so there was an awesome blue glow in the peaks of the waves where the sun couldn't reach.

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Clouds are increasing here once again. They are wave clouds at the mid levels.

Today I saw something interesting that I can't explain. One of those wave clouds sat just to my west for a couple of hours. The flow was from the NW and the skies were clear NW of the wave cloud but the wave cloud didn't move. Somewhat like a cloud that sits over the spine of the Greens with Orographic uplift keeping the cloud stationary over the relief. Thing is that the relief near this wave cloud is flat, there is no sustained uplift keeping the cloud in place. I watched and areas upwind and downwind stayed sunny but under the 5 mile wide wave cloud it remained cloudy. My only possible theory is that the wave cloud was somewhat downwind from Newfound Lake which runs N to South. If the water temps were substantially warmer than the airmass maybe vertical rising of the warm air over the lake would help. Air temps were in the upper 50's and I would guess water temp is around that so I don't think that is it.

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Today I saw something interesting that I can't explain. One of those wave clouds sat just to my west for a couple of hours. The flow was from the NW and the skies were clear NW of the wave cloud but the wave cloud didn't move. Somewhat like a cloud that sits over the spine of the Greens with Orographic uplift keeping the cloud stationary over the relief. Thing is that the relief near this wave cloud is flat, there is no sustained uplift keeping the cloud in place. I watched and areas upwind and downwind stayed sunny but under the 5 mile wide wave cloud it remained cloudy. My only possible theory is that the wave cloud was somewhat downwind from Newfound Lake which runs N to South. If the water temps were substantially warmer than the airmass maybe vertical rising of the warm air over the lake would help. Air temps were in the upper 50's and I would guess water temp is around that so I don't think that is it.

Mountain waves can extend well downstream of the higher elevations before they finally dampen out. Mid level moisture increased from the NE during the afternoon which may explain why you saw nothing to your west at first. I saw them on my way home once I got near my exit around 3pm to the north and they moved overhead around 4-5ish.

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Mountain waves can extend well downstream of the higher elevations before they finally dampen out. Mid level moisture increased from the NE during the afternoon which may explain why you saw nothing to your west at first. I saw them on my way home once I got near my exit around 3pm to the north and they moved overhead around 4-5ish.

 

Learned that while riding in a Cessna 185 almost 20 yr ago on a moderastely windy October day.  Little Bigelow is moderately sloped on its north side, precipitous to the south, and we were headed south.  The pilot, who had been flying for about 50 years, flew over the mt at modest speed to allow for choppy air, then a couple miles south sped up to 130k for the curuise back to Augusta.  That's when we hit the fun; i n 15 seconds he'd chopped back to 80, while the loose items behind the seats bounced around the cabin.  Later, on the gorund, he allowed as that was as nasty a bit of air as he'd ever encountered.  I noted how he had dumped speed, and his deadpan reply, "I thought it would be better if the wings stayed on the airplane."

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Learned that while riding in a Cessna 185 almost 20 yr ago on a moderastely windy October day.  Little Bigelow is moderately sloped on its north side, precipitous to the south, and we were headed south.  The pilot, who had been flying for about 50 years, flew over the mt at modest speed to allow for choppy air, then a couple miles south sped up to 130k for the curuise back to Augusta.  That's when we hit the fun; i n 15 seconds he'd chopped back to 80, while the loose items behind the seats bounced around the cabin.  Later, on the gorund, he allowed as that was as nasty a bit of air as he'd ever encountered.  I noted how he had dumped speed, and his deadpan reply, "I thought it would be better if the wings stayed on the airplane."

 

Mtn waves are my enemy in aviation. Big time issue over the Rockies.

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Just like any other kind of oscillation it doesn't instantaneously stop. The same is true for mountain waves and oscillating air parcels, so yes they can definitely extend a decent distance downstream.

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Good examples of those mountain wave clouds we mentioned earlier.

So what exactly is the cause for that narrow clearing downstream of MWN...is that just a thin line of sinking air or is it just because the moisture is being blocked by the mountain, and there's lower RH in that thin band following the downstream vectors?

I can visualize the mountain wave patterns propagating downstream, with areas of rising air and clouds, followed by sinking air and clear, etc...but am having a hard time with that thin line, as MWN is over-ruling anything else happening in the atmosphere.

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