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January 2016 Pattern Disco


Damage In Tolland

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Figured it would still below freezing here

The freezing rain advisory for tonight has been expanded to include most of MA, N of CT/RI border, including Boston. More details later.

The freezing rain advisory for tonight has been expanded to include most of MA, N of CT/RI border, including Boston. More details later.

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Here's a question for you---what is the threshold that distinguishes a trace from a few hundredths?  

...FREEZING RAIN ADVISORY REMAINS IN EFFECT FROM 7 PM THISEVENING TO 3 AM EST THURSDAY...* LOCATIONS...FRANKLIN COUNTY...NORTHERN WORCESTER COUNTY...  NORTHWEST MIDDLESEX COUNTY. THIS INCLUDES THE CITIES OF  CHARLEMONT...GREENFIELD...ORANGE...BARRE...FITCHBURG AND AYER.* HAZARD TYPES...FREEZING RAIN.* ACCUMULATIONS...A TRACE TO A FEW HUNDREDS OF ICE ACCRETION.* TIMING...BEGINNING BETWEEN 7 PM AND 9 PM AND CONTINUING UNTIL 3  AM.
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Here's a question for you---what is the threshold that distinguishes a trace from a few hundredths?  

...FREEZING RAIN ADVISORY REMAINS IN EFFECT FROM 7 PM THISEVENING TO 3 AM EST THURSDAY...* LOCATIONS...FRANKLIN COUNTY...NORTHERN WORCESTER COUNTY...  NORTHWEST MIDDLESEX COUNTY. THIS INCLUDES THE CITIES OF  CHARLEMONT...GREENFIELD...ORANGE...BARRE...FITCHBURG AND AYER.* HAZARD TYPES...FREEZING RAIN.* ACCUMULATIONS...A TRACE TO A FEW HUNDREDS OF ICE ACCRETION.* TIMING...BEGINNING BETWEEN 7 PM AND 9 PM AND CONTINUING UNTIL 3  AM.

 

A trace wets the surface or less...

 

A few hundredths is astronomical compared to that...   but is still a very small amt in practical terms.  

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It had me consistently seeing 10-12" of snow, Nope

 

Aren't the snow maps predicated on a knee-jerk 10:1 ratio?  Yesterday was the reverse of exactly 2 years earlier, when the modeled 6" or so became 10-13" for our area, due to ratios near 20 rather than 10.  2m temps at my place yesterday were close to the wheelhouse for nice dendrite formation.  Too bad it wasn't that cold about 8,000' overhead.

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Aren't the snow maps predicated on a knee-jerk 10:1 ratio? Yesterday was the reverse of exactly 2 years earlier, when the modeled 6" or so became 10-13" for our area, due to ratios near 20 rather than 10. 2m temps at my place yesterday were close to the wheelhouse for nice dendrite formation. Too bad it wasn't that cold about 8,000' overhead.

That was the biggest problem here, At the surface we never got past 18F, But the warmer air hit into the mid levels further north and sooner then modeled

Sent from my iPhone

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Regime change. Early December.

 

attachicon.gifOlrChiVdiv_tp200hPa_20151210.gif

 

 

Vs now. Note how the Indian ocean is void of anomalous convection as noted in blue. Right now your "blues" are at the dateline. It's a completely different regime change. Your Kara Sea ridge is being built by a massive Icelandic low. This gets cut off and helps the AO go negative. This indeed is at least temporary, but IMHO..I am not sold on this flipping the AO for good...nor am I sold on the Pacific maintaining itself. The 50mb and 10mb looks continue a big Pacific warming, but not SSW yet. 

 

attachicon.gifOlrChiVdiv_tp200hPa_20151228.gif

 

 

I agree regarding the regime shift. I think the changes we're seeing in the NPAC are due to a combination of factors, tropospheric and stratospheric related. Still believe a SSW will not officially occur until around January 20th. No sign of tilting yet, and the upper vortex remains robust until the next WAF burst (although the lower strat vortex will attempt a split via the wave-2).

 

Do you have a link for those great images?

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Yeah, basically saying a trace to "you won't see a tenth of an inch of ice"

 

Maybe like 1/16 of an inch?

few hundredths ... if that much.  

 

1/16 = .0625 and there you have it.   

 

straight up QPF off the NAM is more robust than that, but that's just NAM - btw

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I agree regarding the regime shift. I think the changes we're seeing in the NPAC are due to a combination of factors, tropospheric and stratospheric related. Still believe a SSW will not officially occur until around January 20th. No sign of tilting yet, and the upper vortex remains robust until the next WAF burst (although the lower strat vortex will attempt a split via the wave-2).

 

Do you have a link for those great images?

 

http://ds.data.jma.go.jp/tcc/tcc/products/clisys/anim/anim_tp.html

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It was better then, but what's the usefulness of that? When it comes time to make critical decisions, that's when I need a model to work for me. It failed and failed big in that regard.

 

That's an interesting point.

 

3 days out, when I brief decision makers they aren't looking for details. I can tell them there is the potential for 6 inches or more, and that we'll mix with sleet and possibly some freezing rain, and that it will be worst in the morning. And that's pretty much what happened.

 

But 24 hours out, when they want details and timing, that's when a model crapping the bed really hurts.

 

I appreciate the 50 yard reception, but when it's 1st and goal it's nice to have a model that can carry it over the goal line too.

 

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This SWFE was a little more aggressive in ML warming than usual...but still behaved fairly classic overall. That high position normally may help stop some of the ML warming, but the system was so tilted that we got a situation where 725mb was way warmer than 800mb. It was a little extreme in how strong the inversion was so high up.

 

RGEM and NAM seemed to do the best with the ML warming. Even euro was slightly too cold aloft. RGEM did the best with the low levels though, it kept the interior mostly below freezing, though perhaps not quite enough...NAM was bad and GFS was deplorable.

 

I know it's been mentioned in passing on here, how the NAM used to be the go to for CAD situations. I can safely say the RGEM is my new default for 2 m temps when we're expecting CAD.

 

Some of the time it's not even worth my time to blend in other models, and may go straight RGEM. Our local WRF (similar to BTV) and the HRRR are probably next closest, followed by the ARW and NMM occasionally.

 

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An interesting experiment would be for a met or mets not look at any GFS runs for a week, and see how much it improves forecasts

 

It's catch 22. We have so much more data and levels from the GFS, it can give insight into evolution.

 

For instance the GFS would have told you 750 mb would be warmer than 800 mb. But the Euro we can only see 850 and 700.

 

The GFS is absolutely necessary to weather forecasting, which is what makes it so unfortunate that it's unreliable.

 

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It's catch 22. We have so much more data and levels from the GFS, it can give insight into evolution.

For instance the GFS would have told you 750 mb would be warmer than 800 mb. But the Euro we can only see 850 and 700.

The GFS is absolutely necessary to weather forecasting, which is what makes it so unfortunate that it's unreliable.

Or maybe as part of an inter office study.. Have one guy uses all data except GFS and the other forecaster does use it. Just compare how both forecasts look with and without it
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DT

 

It's also dangerous when only using one model. For instance during the Jan blizzard, both the GFS and EC were stubborn in their solutions. However, knowing how sometimes the EC gets a little too tucked inside 48 hrs...it raised a bit of a red flag. Then the RGEM tickled east and I knew it was too far west, even though it held for another run or two. You gotta know when to hold and know when to fold. I know it's a cheesy line, but you do have to know when and how to use models to your advantage. Another good example was yesterday aftn and evening. I mentioned two days out that there may be a cold tuck. Why? Well we know models are probably too quick to displace low level cold. the 32 isotherm was not going past MHT. No way. So with that in mind...now you have a cold source nearby. When models showed winds going N-NW and the cold coming back down, I figured it may be an issue for metro BOS. Even though temps were not cold enough...that is a big hint that metro BOS may get below 32 with FZDZ. Indeed it came earlier than many expected. 

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