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December 14/15 winter storm threat part II

Typhoon Tip

By Typhoon Tip,
in New England

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moneypitmike

moneypitmike

Posted
Posted

I did my first and final call of 5-9 yesterday, so I have to stick with it.  If I were to redo it, I'd add two inches to the bottom and one to the top.

 

But, returned home from my meeting in VT to discover that  about 2.5" of beautiful powder had descended on the Pit while I was gone.  Given how light it was, it was probably 3 before compacting down.

 

Much to catch up on.

 

21.7/17

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Baroclinic Zone

Baroclinic Zone

Posted
Posted

What did uncle ukie do

 

WPC's take.  Ignore.

MODEL DIAGNOSTIC DISCUSSIONNWS WEATHER PREDICTION CENTER COLLEGE PARK MD216 PM EST FRI DEC 13 2013VALID DEC 13/1200 UTC THRU DEC 17/0000 UTC...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIRINGEST...==============================================12Z MODEL EVALUATION AND PREFERENCES==============================================NAM/GFS INITIALIZATION ERRORS DO NOT APPEAR TOSIGNIFICANTLY AFFECT THEIR LARGE SCALE OUTPUT.==============================================...STORM AFFECTING THE SOUTHERN AND EASTERN U.S...PREFERENCE: BLEND OF 12Z GFS/ECMWFCONFIDENCE: AVERAGEMODELS CONTINUE IN LARGE SCALE AGREEMENT. THERE ARE NOOUTLIERS...AND THE 12Z NAM COULD CERTAINLY BE APPLIED. THE NAMESCAPED OUR PREFERENCE BECAUSE OF SOME DIFFERENCES AT A CRITICALTIME...15/12Z WHEN THE COASTAL PORTION OF THIS STORM ISINTENSIFYING SOUTH OF BOSTON MA. THE SURFACE LOW IN THE NAM ISJUST SLIGHTLY DEEPER THAN THE MULTI MODEL AND ENSEMBLECONSENSUS...AND THIS MAY BE CONTRIBUTING TO MORE STRONGLY BACKEDSURFACE WINDS AND COLDER THERMAL PROFILES IMMEDIATELY NORTH OF THELOW TRACK. THIS IDEA IS CERTAINLY PLAUSIBLE AND SHOULD NOT BEIGNORED...BUT FOR OUR PREFERENCE WE SIDE WITH THE EXCELLENTAGREEMENT AND CONTINUITY SEEN IN THE LARGER SCALE GUIDANCE. THEUKMET IS NOT INCLUDED BECAUSE IT HAS TENDED TO TAKE THE SURFACELOW SLIGHTLY NORTH OF CONSENSUS WITH WARMER THERMAL PROFILES OVERSOUTHERN NEW ENGLAND. THE 12Z CANADIAN DOES SUPPORT THEUKMET...WHERE IT HAD SUPPORTED THE LARGER CONSENSUS DURINGPREVIOUS CYCLES. THE MAJORITY OF ENSEMBLE GUIDANCE IS STILL STEADYIN DEPICTING A LOW TRACK SLIGHTLY SOUTH OF THE 12Z UKMET ANDCANADIAN SOLUTIONS.
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N. OF PIKE

N. OF PIKE

Posted
Posted

I guess you never read Chris explanation from this am about accumulation ranges

Sure it could , maybe best case , and on other side of cf yup but color me skeptical

And no i was working 530-1200, did Chris have high confidence or say it "could happen"

And to be clear im talkin the 14-18 on immediate coast from Portsmouth to somewhere s of Salisbury mass and west 10-15 miles from those two spots.

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dryslot

dryslot

Posted
Posted

Sure it could , maybe best case , and on other side of cf yup but color me skeptical

And no i was working 530-1200, did Chris have high confidence or say it "could happen"

 

The example he use this am when it showed 8-10" is that they felt the map portrayed the higher end at 10", Bit if they added .01" to the map it bumped it to 10-14" range, That's why he said its a range, That area that has the 14-18" could very well only be the 14" total if you follow, And that is the area that the models have targeted to be in the sweet spot, It could very well be 14.1" but it kicks it to this range

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N. OF PIKE

N. OF PIKE

Posted
Posted

The example he use this am when it showed 8-10" is that they felt the map portrayed the higher end at 10", Bit if they added .01" to the map it bumped it to 10-14" range, That's why he said its a range, That area that has the 14-18" could very well only be the 14" total if you follow

Ahh ok, i follow and i think the 14 is best case top of potential scenario and right at mass/nh coastline im very skeptical thats all. Nbd.

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moneypitmike

moneypitmike

Posted
Posted

At least it's not going apesh*t relatively speaking, but I will not get NAM snow amounts..lol.

 

Boy the 18z NAM sure is in and out quickly.

 

I'm way too far behind to catch up--is it going to snow here or what? :)

 

Also, what's the deal on ratios?  I guess these should be pretty run-of-the-mill given the forecasted snowfall and modeled qpf.   

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CoastalWx

CoastalWx

Posted
Posted

maybe not nam snow amounts, buts its certainly within reason to keep your yard mostly snow.....on the right side of the CF.

 

I expect a lot of it to be snow. But, I will need really good precip rates. It will be a strong ENE wind. Basically you want something where the temp rapidly decreases with height. IOW, say my temp goes to 33F. If Blue Hills at 635' is like 29-30, then I'm fine. When they warm to like 32F and there is maybe 1-2F difference in temps, that's when there is an issue. A lot of times on the coast esp early in the season, the lower 500 feet torch thanks to conduction with the warmer water. However if 950mb temps are like -2C or colder..then some of that can mix down and keep temps near 32F. This happened on 12/16/07 where Logan had S+ and screaming east winds. It was frigid aloft. It will start out that way, but it will warm up real quick near 950 after 06z.  A difference of 2hrs means the difference of 1-3"+ possibly so you see the bust potential is high. I want to side cold..but I can't have the track near the canal. I'd feel much better with a NAM track.

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Tropopause_Fold

Tropopause_Fold

Posted
Posted

the other thing to consider is the euro more or less (850 a bit further N) has the 925 to 850 0C lines aligned by 12z...and they are essentially running from just NW of BOS...WSW down the pike to BDL-ish. a big slug of precip falls during that 06z to 12z window - like .5 to .75 in a lot of areas. at 6z, everything is solidly still sub-freezing in the column throughout SNE. sometime in that 6 hr window a lot of the region is going to mix or flip by the looks of it. timing will be key. if it's closer to 10 or 11z, the majority of the precip is probably over and it'll just end as drizzle and light sleet and maybe some light ice. if it's more like 8z...then a solid chunk of precip is going to be non-snow. 

 

euro soundings show this pretty well - just wish there was a 3-hr increment available to see. 

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RUNNAWAYICEBERG

RUNNAWAYICEBERG

Posted
Posted

I expect a lot of it to be snow. But, I will need really good precip rates. It will be a strong ENE wind. Basically you want something where the temp rapidly decreases with height. IOW, say my temp goes to 33F. If Blue Hills at 635' is like 29-30, then I'm fine. When they warm to like 32F and there is maybe 1-2F difference in temps, that's when there is an issue. A lot of times on the coast esp early in the season, the lower 500 feet torch thanks to conduction with the warmer water. However if 950mb temps are like -2C or colder..then some of that can mix down and keep temps near 32F. This happened on 12/16/07 where Logan had S+ and screaming east winds. It was frigid aloft. It will start out that way, but it will warm up real quick near 950 after 06z.  A difference of 2hrs means the difference of 1-3"+ possibly so you see the bust potential is high. I want to side cold..but I can't have the track near the canal. I'd feel much better with a NAM track.

 

cool thoughts, understood. you deff know your local climo. unfortunately this is one of those events were your local is the battle ground which makes forecasting a nightmare.

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Damage In Tolland

Damage In Tolland

Posted
Posted

It just seems like this whole mixing thing is getting blown out of proportion..Every analog to this storm had a warmer antecedent airmass. I think this is going to be simiiar to what we saw last weekend around philly and there's going to be quite a few surprises when folks see how long it stays snow for and how much they get. IMO it will be 90% snow for most folks even in BOS

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dryslot

dryslot

Posted
Posted

Ahh ok, i follow and i think the 14 is best case top of potential scenario and right at mass/nh coastline im very skeptical thats all. Nbd.

 

And i agree,  With whats being modeled right now, Of course things can change but i think we are at the qpf limits for this one with as fast as its moving

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Cold Miser

Cold Miser

Posted
Posted

It just seems like this whole mixing thing is getting blown out of proportion..Every analog to this storm had a warmer antecedent airmass. I think this is going to be simiiar to what we saw last weekend around philly and there's going to be quite a few surprises when folks see how long it stays snow for and how much they get. IMO it will be 90% snow for most folks even in BOS

Just heard Bob Maxon throw out the snow to sleet and rain set up for the entire state of ct. with the high end being 8".  He did seem to think the totals would be on the high end.

 

YOU can't ignore today's best mix.  It's coming.

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