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NNE Fall 2012


ctsnowstorm628

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The 06z GFS model sounding for Rutland, VT (RUT) @21z Tuesday shows the strong downslope easterly wind potential based on the further north solution along the western slopes of the Green Mtns. The low-level lapse rates also modulate the extent to which downslope winds occur. Will be interesting to see the NAM and other mesoscale models as we get into the short-range to better resolve this, but the synoptic pattern is favorable with a further north track similar to 06z GFS. If the more southern ECMWF track is correct, we wouldn't see the background flow to cause damaging winds along the western slopes, so the track is key.

RUT_gfs_sounding_21zTue.jpg

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Yeah that downslope wind potential looks pretty good. The pressure gradient winds working east and down over the Spine into the west slope communities will likely provide the highest wind gusts in this area. When I lived in Jonesville/Richmond we used to get them off Camels Hump on SE flow and I think we lost power every single time there was a SE flow event.

It is amazing to hear the roar though of the downslope winds though... it may mean a lot less rain on the west slope, but I always found it fascinating that it could be pouring precipitation in Waterbury on the east side, and in Burlington to the west, while its partly cloudy and downsloping on the west slope of the Spine.

AT THIS TIME...FAVORABLE SOUTHEAST DOWNSLOPE WINDS

SHOULD DEVELOP AND ENHANCE THE POTENTIAL FOR STRONG WINDS ALONG

THE WEST SLOPES OF THE GREEN MOUNTAINS. HOWEVER...WHAT IS BEING

WATCHED IS A MORE NORTHWARD TRACK OF SANDY BECAUSE THAT WOULD SET

UP A MUCH LARGER WIND THREAT...BOTH IN MAGNITUDE AND AREAL

COVERAGE OVER THE AREA. PATTERN WOULD BE COMPARABLE TO THE APRIL

16TH 2007 WINDSTORM THAT BROUGHT DAMAGING WINDS TO A LARGE PART OF

VERMONT. AGAIN...RIGHT NOW BASED ON THE OFFICIAL TRACK OF SANDY

FROM THE NATIONAL HURRICANE CENTER AS OF 2AM...THE SOUTHEAST

DOWNSLOPE SCENARIO IS THE ONE TO FOLLOW AND HAVE ADJUSTED GRIDS TO

BRING IN BREEZY TO WINDY CONDITIONS ACROSS THE AREA...BUT WILL

CONTINUE TO MONITOR FOR A MORE NORTHWARD LANDFALL OF SANDY.

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Was it cloudy in Burlington all day or something? I cannot for the life of me figure out what is up with these temperatures... high/lows listed:

BTV...61/56 (what's up with the only 5F diurnal spread today?)

MVL...71/39 (+18 on the high, +6 on the low)

MPV...67/39 (+14 on the high, +6 on the low; MPV and MVL have the same 53/33 average listed, which is odd considering MPV is almost 500ft higher in elevation)

1V4...69/40 (+15 on the high, +6 on the low; also find it hard to believe St Johnsbury's average temps are warmer than MVL/MPV)

SLK...68/35 (+18 on the high, +6 on the low)

Pretty consistent departures from average at all the mountain valley stations... all come in with a +6 on the overnight minimum. But I cannot get over how BTV only had a 5F diurnal change today while spots like Morrisville-Stowe and Saranac Lake had over 30F differences between high/low. Also, its very rare for BTV to have the lowest high temperature of all the stations up here, and by a long shot. Staying 6-7F colder than spots like SLK and MPV which are both well over 1,000ft higher in elevation.

Something funky must've been going on at BTV because they reported overcast skies all day while it was a beautiful mostly sunny day at all the observing stations in the Adirondacks and Greens.

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Ahhh this is why BTV was so much colder and cloudier than everyone else today....

MODIFIED CLOUD COVER TO BE QUITE PERSISTENT ACROSS

CHVLY/SRN VT OUTSIDE THE HIGHEST TERRAIN OF THE CENTRAL/SRN GREENS

THROUGH THE DAY AS LL MOISTURE AND STRONG INVERSION NEAR 950 MB

HOLDS STRONG. AS A RESULT HAVE LOWERED MAX TEMPS BY 3-5 DEG IN

THESE AREAS ACCORDINGLY. ELSEWHERE...CONSIDERABLY MORE SUNSHINE

AND WARMER...ESP SLV WHERE READINGS WELL INTO THE 70S (SIMILAR TO

YESTERDAY) MAY THREATEN DAILY RECORDS.

I wish I had looked at a satellite image this afternoon... must've looked cool with everyone but the Champlain Valley in the sunshine. Odd that the strong inversion in the Champlain Valley was able to hold strong all afternoon and kept temps 5-10F colder than all the mountain valleys.

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Took till about noon yesterday for the low-level clouds to erode but once they did, it was a lovely afternoon--soft, gentle air, washed out blue skies and quite mild. Took the day off to give me a three-day weekend--putting up the winter's worth of firewood.

The fog's pretty thick again this morning--thicker than yesterday, actually. I can't even see the big hill behind us, less than a half mile away.

All eyes on Sandy, of course. Not much for me to do here other than make sure the chainsaw is ready to go (it is) in case I have to cut my way up the driveway come Tuesday morning. ;)

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Heavy, heavy fog this morning. Still in the 1/4-1/2SM goop.

Yep similar here. I just drove up to the ski area for a minute to pick something up and it was 47F with dense fog at 800ft....then bluebird and 55F at 1500ft. Inversion is right at 1400ft or so. On the way back down the hill it was into the fog and temp dropped back down into the 40s.

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Since we’re into November next week, I’ve been checking the extended forecast for the past few days, and snow has finally started to reappear in the valley and mountain forecasts as of today. Mt. Mansfield point and click suggests some snow potential toward the end of the week:

 Thursday Night A chance of rain and snow showers. Cloudy, with a low around 35. Breezy. Chance of precipitation is 50%.

 Friday A chance of rain and snow showers. Cloudy, with a high near 37. Breezy. Chance of precipitation is 40%.

 Friday Night A chance of snow showers. Cloudy, with a low around 27. Windy. Chance of precipitation is 30%.

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Shut up, Brian. SHUT UP!!! cry.gif

After today, I don't even have a chance of clouds in my forecast for the next week. cry.gif

Sorry. sad.png

Was playing around with BUFKIT just now and looking at the peak momentum transfer winds. f you take an avg of the mixed layer and the wind at the top of the mixed layer you get this for potential peak gusts...

Station 12zNAM/12zGFS

CON 51kt/32kt

MHT 50kt/31kt

PSM 52kt/45kt

BOS 49kt/46kt

EWB 50kt/40kt

BDR 58kt/55kt

I'd probably take those GFS numbers and add a good 10-20kt to them.

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Question for you Brian. Why does the NAM show 10m winds higher up here in Central NH than down in interior Mass? I really have not been paying attention too much for us with a storm so far to the south. In 1938 we had a cane moving quickly just to our west which is very different than this storm. Off course, what do I know dealing with a 940 something storm to the south and a high to the north. Better get an extra tank for the generator just in case.

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Question for you Brian. Why does the NAM show 10m winds higher up here in Central NH than down in interior Mass? I really have not been paying attention too much for us with a storm so far to the south. In 1938 we had a cane moving quickly just to our west which is very different than this storm. Off course, what do I know dealing with a 940 something storm to the south and a high to the north. Better get an extra tank for the generator just in case.

The map I showed was the time more favorable for us. That LLJ progresses northward during the day tomorrow.
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A few BTV forecast maps for this storm... thanks to any BTV forecasters who read this thread. The maps you guys/gals produce are pretty sweet. Wish more offices had these.

Rainfall... not overly impressive by any means. We are too far north and a lot of the water gets squeezed out over the Whites on the strong easterly flow. I am surprised though at the lack of rain the models have for the area, even though PWATS are like 200% of normal for this time of year. Anyway, this is definitely a ESE flow that favors Allenson of any of our VT posters.

Wind... max possible gusts looks pretty good in theory from the models... but I'm really skeptical down under 1,000ft in the mountain valleys like Morrisville's 63mph. I'll eat my hat if the MVL ASOS gusts to 60mph or higher. We are sheltered by multiple 3,000-4,000ft ridgelines (Mansfield and the Worcester Range) and its usually hard to realize high winds down here at the bottom of the fish bowl at 700-1000ft. I feel like that's a similar situation all around interior VT at elevations of 1,000ft or lower. We either inversion out and keep winds high, or the terrain disrupts the flow enough. But maybe the terrain disrupting the flow will result in higher winds mixing down? I just know from experience that here it seems like the low level jet goes over both ridgelines (one to the west, one to the east) leaving us relatively calm. Now the western slopes should get lit up. My experience living in the Jonesville/Richmond area is they downslope like its their job and even run of the mill winter storms with SE flow can gust 60mph or higher. With this type of strong H85 easterly flow, all the west slope communities can probably bank on not having power Tuesday morning.

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I'm with PF. I'm not that impressed with what this storm will do to VT. Gusting 70-80 isn't that impressive along the ridgelines. We see that strength several times a winter. I'm sure there will be power outages but nothing super impressive.

Yeah, doesn't look too bad but still something to watch anyway. I'm just hoping for some decent gusts here in deepest eastern Vermont, where winds go to die.

Kind of an eerie yellow/green dawn here underway...

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Yeah, doesn't look too bad but still something to watch anyway. I'm just hoping for some decent gusts here in deepest eastern Vermont, where winds go to die.

Kind of an eerie yellow/green dawn here underway...

Haha I thought winds go to Stowe to die? I can't say I can ever remember 40-50mph gust here in the protected village below 1000ft. It's amazing how different it can be up at the ski area 1500ft+.

This morning it is dead calm at the sfc while I can see scud hitting the mountain at 3000ft that appears to be moving at highway speeds haha. Definitely breezy aloft.

BTV had a great wind discussion last night, and as I was hinting last night, having the low level jet go up over the ridgelines limits wind here in Stowe, BTV just explained it nicely in the AFD:

Winds: overall...still anticipating high winds across the north country with gusts between 50 and 60 miles per hour cpv/slv and between 60 and 80 miles per hour western slopes...nek...and hir terrain above 2000 feet of the dacks/Green Mountains still some uncertainty with regards to wind speeds across the deeper valleys of central/northern Vermont and parts of the cpv...per stable low levels limiting deep layer mixing. Soundings at btv show top of the mix layer wind of 58 knts...when transferred to the surface supports gusts around 50 miles per hour. Meanwhile...at rut/1v4 top of the mixed layer is between 60 and 65 knts...which combined with favorable downslope momentum Transfer on easterly winds...supports wind gusts between 65 and 70 miles per hour. Still thinking very stable low level on upslope side of the Green Mountains will limit high wind threat from Ludlow to Waitsfield to Stowe...as air will be rising as it hits the mountains and momentum Transfer to the surface will be minimum. Expect gusts between 35 and 45 miles per hour. The high resolution NAM/arw and local wrf's show very strong up/down Omega fields between 925mb and 850mb...indicating the effects of the mountains on the easterly follow. Very difficult to show these types of small scale features in the grids...but expect a wide range in wind speeds from one location to another on Monday aftn/evening. Meanwhile...for exposed hir elevations of the dacks/Green Mountains above 2000 feet...where surface friction is minimum...would anticipate gusts between 60 and 80 miles per hour...with gusts up to 90 miles per hour possible at Mount Mansfield. "

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I'm with PF. I'm not that impressed with what this storm will do to VT. Gusting 70-80 isn't that impressive along the ridgelines. We see that strength several times a winter. I'm sure there will be power outages but nothing super impressive.

Yeah...valleys MAY gust to 50mph...maybe 70-80mph above 2k. Maybe. It's going to be very local. The NWS was pushing a NEK hotspot for wind, but really everything I'm looking at is very, very microscale. Nothing impressive at all, really for civilized areas.

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Was just out on lunch break and went down to a boat landing on the CT River. Blowing & gusting smartly from the NE, funneling right down the valley. Had a few gusts that I would guess were around 30 or so. KLEB reporting gusts to 31, so I would say I was at least in the ballpark with my estimation.

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euro looks cold after day 3. esp for VT snowy as well in upslope regions and hills

Yeah, just listened to Roger Hill’s forecast and it looks like it will be cooling down with each day that passes this week. He even mentioned snow back down to the valleys by the weekend. I see the wintry point and click icons working their way in for Mt. Mansfield starting tomorrow night:

30OCT12A.jpg

It’s too bad that the NNE mountains weren’t in the cold section of the current storm like West Virginia, but we’re into November, so snow’s almost inevitable now.

As for the effects of Sandy in our area, things went pretty smoothly as far as I can tell. We definitely heard some gusts of wind yesterday evening, but we haven’t even had any power flickers that we know of yet, and I didn’t see any limbs or anything else down on my drive this morning. I’m sure having all the leaves off the trees helped keep wind issues lower than they might have been. It was actually very pleasant out there this morning, with a tropical/summery feel; 0.45” of liquid in the rain gauge as of 6:00 A.M.

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