March 13th ... west Atlantic bombogenesis type low clipping SE New England, more certain ...may be expanding inland

[Cold Miser]

lol - NWS is calling for 10-16 for my area via the good ole' point and click disaster.

I don't think it will be above 10, but if so would be the biggest storm of the season here. 

[CoastalWx]

1 minute ago, mahk_webstah said:

What do you all think of the time of peak conditions at BOS?  I'm thinking heavy by Tues morn and peaking Tues afternoon?  Then lighter snow but windy Tues eve?

Sounds about right.

[OceanStWx]

3 minutes ago, JC-CT said:

It's computer generated from wpc ensembles? I thought I read that somewhere

The basic premise is we create a snowfall forecast. WPC has an “ensemble” that is a blend of many models. From that blend they develop a cumulative density function that is the total range of snowfall amounts. Our forecast becomes the center of that CDF. And the 10/90th percentiles of that CDF are the maps you see. 

So if we shift the forecast, that shifts the 10/90th percentiles.

[mahk_webstah]

1 minute ago, CoastalWx said:

Sounds about right.

You probably know my agenda here....Wed am is the first leg of a 6 leg around the world trip, starting in London.  If I miss it I'm screwed.  Also hate to miss a good storm by leaving tonight.  Considering driving to NYC and flying from there early Wed, or catching and early BOS-JFK flight connecting to London Wed morn since I'd think Logan would be open by 6am Wed.

In terms of weather itself, there is a consistent signal for 1" or more qpf all the way up here (now in Boscawen permanently) even with a track outside the benchmark.  Is it the mid level track or is it the strength of the NS pulling back moisture up here sort of like an Inv Trough?

[TalcottWx]

Nothing better than a peaking blizzard during the day time. Nothing. 

[weathafella]

18 minutes ago, wxsniss said:

While Ginx is getting rest...

This map also suggests some decent banding in western areas into Logan11 land but maybe some awful screw zones in the middle.

[Hoth]

Well, first off, congrats to NoPoles and Jimmy for finally catching a break. Second, my visual hallucinations continue. Looks to me like the n/s is already starting to slip down the backside of the s/s. I just keep thinking, "how is this not coming more west?"

[weathafella]

3 minutes ago, sbos_wx said:

Nothing better than a peaking blizzard during the day time. Nothing. 

Strongly agree!  

[JC-CT]

4 minutes ago, OceanStWx said:

The basic premise is we create a snowfall forecast. WPC has an “ensemble” that is a blend of many models. From that blend they develop a cumulative density function that is the total range of snowfall amounts. Our forecast becomes the center of that CDF. And the 10/90th percentiles of that CDF are the maps you see. 

So if we shift the forecast, that shifts the 10/90th percentiles.

But you aren't setting the high and low maps yourself, right? I feel like the confusion is that people think there was any thought put into them. I am under the impression that the only thing the local office controls is the expected amount.

[weathafella]

Just now, Hoth said:

Well, first off, congrats to NoPoles and Jimmy for finally catching a break. Second, my visual hallucinations continue. Looks to me like the n/s is already starting to slip down the backside of the s/s. I just keep thinking, "how is this not coming more west?"

James should rent a room in Diane’s house.  I think he may have some problems as far east on the cape he is.

[CoastalWx]

5 minutes ago, mahk_webstah said:

You probably know my agenda here....Wed am is the first leg of a 6 leg around the world trip, starting in London.  If I miss it I'm screwed.  Also hate to miss a good storm by leaving tonight.  Considering driving to NYC and flying from there early Wed, or catching and early BOS-JFK flight connecting to London Wed morn since I'd think Logan would be open by 6am Wed.

In terms of weather itself, there is a consistent signal for 1" or more qpf all the way up here (now in Boscawen permanently) even with a track outside the benchmark.  Is it the mid level track or is it the strength of the NS pulling back moisture up here sort of like an Inv Trough?

It's the mid levels, and that is thanks to the interaction of the nrn and srn stream s/w's.

 

I dunno, I'm definitely not confident in big numbers at this time. I see a few Scooter flags that keep me in check for now. Yeah yeah....I know about banding and some lucky weenies who may get into it, but a wide area of 12-18+?? Not there yet.

[JC-CT]

1 minute ago, Hoth said:

Well, first off, congrats to NoPoles and Jimmy for finally catching a break. Second, my visual hallucinations continue. Looks to me like the n/s is already starting to slip down the backside of the s/s. I just keep thinking, "how is this not coming more west?"

Hey, I was considering posting about it but then I thought it was so low probability that it wasn't worth it to weenie over. But if there are any tricks left up this one's sleeve, it is with the northern stream. A lot of it hasn't been raob sampled yet, including the energy that creates that late diving shortwave, which could affect the trough orientation ever so slightly one way or the other.

[Hoth]

1 minute ago, weathafella said:

James should rent a room in Diane’s house.  I think he may have some problems as far east on the cape he is.

Really? I hadn't looked too closely. I thought 850s were plenty cold even there.

[Hoth]

2 minutes ago, JC-CT said:

Hey, I was considering posting about it but then I thought it was so low probability that it wasn't worth it to weenie over. But if there are any tricks left up this one's sleeve, it is with the northern stream. A lot of it hasn't been raob sampled yet, including the energy that creates that late diving shortwave, which could affect the trough orientation ever so slightly one way or the other.

We'll just set our expectations low and hope for a surprise. I mean, that PNA is pumped, the block is holding steady and the trajectory on the n/s energy seems more north/south to me. 

[rnaude241]

I like my spot for this one for once. I have been reeling this one in for a big hit down here, but as I said earlier I'd be happy with 6-12. 

[JC-CT]

Just now, Hoth said:

We'll just set our expectations low and hope for a surprise.

Dylan's map is reasonable IMO as long as someone doesn't look at it and only see the high end of the range.

[wxsniss]

Just now, weathafella said:

This map also suggests some decent banding in western areas into Logan11 land but maybe some awful screw zones in the middle.

Yep very clear banding signatures on 12k / 3k NAMs... we gotta be careful playing with these meso features, I think the 6z 3k NAM had us in a relative sub zone for a brief time... kept us more 11-13" rather than 14"+ on both sides... all too far out to nail down any of this of course

This is killing my work / sleep...! I bargained with myself that this will (probably) be the final hurrah for the season.

[OceanStWx]

5 minutes ago, JC-CT said:

But you aren't setting the high and low maps yourself, right? I feel like the confusion is that people think there was any thought put into them. I am under the impression that the only thing the local office controls is the expected amount.

Right. The only “setting” we do is by moving our expected amount.

If the CDF has a 12” range, and our expected was 8”, the max/min would be something like 2-14”.

If we then decide to increase snow amounts to 11”, that max/min becomes something like 5-17”

[mahk_webstah]

6 minutes ago, CoastalWx said:

It's the mid levels, and that is thanks to the interaction of the nrn and srn stream s/w's.

 

I dunno, I'm definitely not confident in big numbers at this time. I see a few Scooter flags that keep me in check for now. Yeah yeah....I know about banding and some lucky weenies who may get into it, but a wide area of 12-18+?? Not there yet.

I agree. It seems really aggressive, but GYX has been aggressive for several days and they often aren’t 

[JC-CT]

Just now, OceanStWx said:

Right. The only “setting” we do is by moving our expected amount.

If the CDF has a 12” range, and our expected was 8”, the max/min would be something like 2-14”.

If we then decide to increase snow amounts to 11”, that max/min becomes something like 5-17”

How does it sometimes end up that the expected will be almost exactly the high range, like 10" expected with a high range of 11", but the low range will be like 2" or something?

[Chrisrotary12]

Here is the map that I ran with for my blog yesterday afternoon.

[JC-CT]

Just now, Chrisrotary12 said:

Here is the map that I ran with for my blog yesterday afternoon.

That's solid for SNE outside the berks. I think you missed the upslope potential though.

[J Paul Gordon]

13 minutes ago, weathafella said:

This map also suggests some decent banding in western areas into Logan11 land but maybe some awful screw zones in the middle.

Looks like Worcester (especially east side) gets into some of that banding while 20-30 miles west of us gets screwed.

[mahk_webstah]

2 minutes ago, Chrisrotary12 said:

Here is the map that I ran with for my blog yesterday afternoon.

You are clearly not buying the big QPf numbers back into central New Hampshire and Western New England

[HIPPYVALLEY]

13 minutes ago, weathafella said:

This map also suggests some decent banding in western areas into Logan11 land but maybe some awful screw zones in the middle.

My area may be trapped in the exhaust zone between epic bands for the 2nd time in a week. 

[dendrite]

2 minutes ago, JC-CT said:

That's solid for SNE outside the berks. I think you missed the upslope potential though.

PF just had a stroke

[JC-CT]

1 minute ago, dendrite said:

PF just had a stroke

He's expecting 2' of powder and ends up with a coating lol

[J Paul Gordon]

2 minutes ago, JC-CT said:

That's solid for SNE outside the berks. I think you missed the upslope potential though.

East slope of the Berks and Worcester hills do well with upsloping, often there are screw zones to our west, their east (namely the Pioneer/Connecticut valleys.)

[dendrite]

Just now, HIPPYVALLEY said:

My area may be trapped in the exhaust zone between epic bands for the 2nd time in a week. 

My hunch is the band is closer to you and not over Logan in NY.

[OceanStWx]

4 minutes ago, JC-CT said:

How does it sometimes end up that the expected will be almost exactly the high range, like 10" expected with a high range of 11", but the low range will be like 2" or something?

Well not all CDFs look like a perfect bell curve like I described.

Some have a big low end tail, but a sharp high end. Sometimes all models say rain and there is no CDF to work off of. It’s definitely not a fool proof system, but it can provide some windows into the guidance. 

It works best for large, widespread snow events.