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December 14/15 winter storm threat


Typhoon Tip

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MOS snowfall amounts (one of Jerry's tools) from the 18z GFS are showing 8 (8"+) across a huge portion of the interior even including up here at BTV/MVL/MPV...PSF/ORE/FIT/MHT/CON and it has 6 (6-8") for BOS/BVY/BED/LWM (but there may be additional snow afterwards?). 

 

NAM MOS is pretty much 8 across the board for Mass and NH sites.

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Your area looks good. Should be decent banding there too. And I don't know how you think the NAM isn't funny. Just think back to the last 24 hrs, and then look at this solution. Sure it has an outside shot of being viable...but the model sucks.

I think the NAM might have basically the right idea.  It has shifted somewhat, sure, but all guidance has.  The surface charts on NCEP can look misleading... especially the low res 850mb 0 line on the 6-hr QPF chart.  The mid and upper levels on the NAM haven't changed that much since yesterday.

 

The 12z Euro illustrates my concern for ENY.  Steady light snow has trouble getting going on Saturday with the best QPF off to the S and SE.  Then the developing coastal mostly misses the area.  Overall QPF up here is modest on the Euro.  I'm counting on good ratios on Sat... but it doesn't help much with really weak lift.  And surface temps in the valley won't be frigid (probably well above the magical 15F), there's usually more dry air than modeled with an arctic high, and the snow growth zone might warm above optimal temps Saturday night... as the best lift moves through.  I would go with 15:1 for ALB... much higher in the Dacks and NNE.  I like NH and coastal ME right now for this one.

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All the Boston mets seem to have a similar snowfall map at this point ... 3-6 inside of 128 including Boston and extending west just south of the MA border and just N of 84 with 5-10" for all areas northwest of that line, and 1-3" for the cape and islands SE of PYM and along the south coast.

 

Overall it seems pretty reasonable. My area to Jerry are probably  in a battle zone depending on how the coastal front takes shape. I'm thinking 4-8" currently for this area.

 

Seems very reasonable based on current model consensus.

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I think the NAM might have basically the right idea.  It has shifted somewhat, sure, but all guidance has.  The surface charts on NCEP can look misleading... especially the low res 850mb 0 line on the 6-hr QPF chart.  The mid and upper levels on the NAM haven't changed that much since yesterday.

 

The 12z Euro illustrates my concern for ENY.  Steady light snow has trouble getting going on Saturday with the best QPF off to the S and SE.  Then the developing coastal mostly misses the area.  Overall QPF up here is modest on the Euro.  I'm counting on good ratios on Sat... but it doesn't help much with really weak lift.  And surface temps in the valley won't be frigid (probably well above the magical 15F), there's usually more dry air than modeled with an arctic high, and the snow growth zone might warm above optimal temps Saturday night... as the best lift moves through.  I would go with 15:1 for ALB... much higher in the Dacks and NNE.  I like NH and coastal ME right now for this one.

 

The NAM misses Maine with QPF..lol. It's junk, not even worth an argument.

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I miss the NGM very much for QPF and for the exact reason Will stated, it was better at qPF placement in big events

 

 

The FWC guidance from it was pretty darn good too. Its one of the reasons they kept running the NGM until 2009 when they were originally going to retire it in 2002.

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I miss the NGM very much for QPF and for the exact reason Will stated, it was better at qPF placement in big events

Well it was tremendously coarse...it pretty much only picked up synoptic/QG forcing. As a forecaster you can work with that if you know your mesoscale meteorology for different situations.

 

The only thing I really miss it for is MOS.

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MOS snowfall amounts (one of Jerry's tools) from the 18z GFS are showing 8 (8"+) across a huge portion of the interior even including up here at BTV/MVL/MPV...PSF/ORE/FIT/MHT/CON and it has 6 (6-8") for BOS/BVY/BED/LWM (but there may be additional snow afterwards?). 

 

NAM MOS is pretty much 8 across the board for Mass and NH sites.

 

I don't feel this is a point that should be over-looked...  MOS is a blend of interpretative algorithms ... sloped toward climo. 

 

We know collectively that intense arctic wedges of air with WAA running up normal to the isotherms tends to overproduce.  That is a conclusion derived not just from common experience, but by statistical results.  Just think circa 2007 ... "SWFE" are almost entirely dependent on busting high.   

 

Initially this is WAA but then we see discerned coastal cyclogen coming into greater coherence from the Del Marve to ACK or perhaps the Bowel Movement;  we may over-perform in the front on this thing.  

 

I dunno if that would translate all way toward you neck of the woods

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The NAM misses Maine with QPF..lol. It's junk, not even worth an argument.

I would hedge toward the Euro/GEM/GFS with the track past ACK.  The NAM is already about .5" in coastal NH and ME.  Maybe bump that up a bit.  Not too terrible IMO.  The Euro might be easier to criticize if it had more accessible graphics and was run every 6 hours.

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The NAM shifted around the H5 features by a decent amount. If you combine that with the fact it is a non-hydrostatic model, consistency is non-existent. 

 

So did the Euro.  Look at the depiction for h24 last night vs h12 today and where things actually are as we approach 0z.

 

More changes incoming tonight IMO.  Not the strong suit of the Euro (energy coming out of the SW)

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I don't feel this is a point that should be over-looked...  MOS is a blend of interpretative algorithms ... sloped toward climo. 

 

We know collectively that intense arctic wedges of air with WAA running up normal to the isotherms tends to overproduce.  That is a conclusion derived not just from common experience, but by statistical results.  Just think circa 2007 ... "SWFE" are almost entirely dependent on busting high.   

 

Initially this is WAA but then we see discerned coastal cyclogen coming into greater coherence from the Del Marve to ACK or perhaps the Bowel Movement;  we may over-perform in the front on this thing.  

 

I dunno if that would translate all way toward you neck of the woods

 

Yeah probably not, but I was impressed that the GFS MOS had 8+ for every station in VT.  Its seeing something in the set-up and past set-ups that it likes up this way.

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I just noticed that most GEFS members are slow bringing snow in on Saturday.  Many hold off until evening and overall they are pretty dry during the day.  I know there are differing opinions regarding how quickly snow moves in with WAA into arctic air, but guidance has very gradually slowed precip onset.

 

There are also a handful of members that are pretty wet and warm throughout SNE late Sat night - but also pretty snowy.  A few even appear to bring the mix line into NW MA and ENY.

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I just noticed that most GEFS members are slow bringing snow in on Saturday.  Many hold off until evening and overall they are pretty dry during the day.  I know there are differing opinions regarding how quickly snow moves in with WAA into arctic air, but guidance has very gradually slowed precip onset.

 

There are also a handful of members that are pretty wet and warm throughout SNE late Sat night - but also pretty snowy.  A few even appear to bring the mix line into NW MA and ENY.

Most guidance has snow into Ct in the morning and up to Mass by afternoon

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