Dec 9th Winter Threat

[N. OF PIKE]

South of pike special w those predecessor bands? I think the hills in sw ct over to rev needs to watch those initial bands bc they could be decent.

I wonder if the western RI hills get some sort of enhancement w winds generally light onshore.

[CoastalWx]

South of pike special w those predecessor bands? I think the hills in sw ct over to rev needs to watch those initial bands bc they could be decent.

I wonder if the western RI hills get some sort of enhancement w winds generally light onshore.

Model winds are too easterly in the beginning. This will probably be more of a 040 direction over the interior. Winds also will be very light even on the coast until after 12z tomorrow.

[N. OF PIKE]

Model winds are too easterly in the beginning. This will probably be more of a 040 direction over the interior. Winds also will be very light even on the coast until after 12z tomorrow.

So this wont be a sneaky event where the pawtuxet river enhancement rivals the tug for isolated locale's near ginxy and the Dead Sea scrolls.

[Tropopause_Fold]

Model winds are too easterly in the beginning. This will probably be more of a 040 direction over the interior. Winds also will be very light even on the coast until after 12z tomorrow.

just my thought...but i feel like they should have just pushed the wwa right to the coast. 

[CoastalWx]

So this wont be a sneaky event where the pawtuxet river enhancement rivals the tug for isolated locale's near ginxy and the Dead Sea scrolls.

If that first band can push north enough, it may be a slight surprise for the south coast. High pressure is strong though and wil eat up the echoes as it moves NE.

[CoastalWx]

just my thought...but i feel like they should have just pushed the wwa right to the coast.

I didn't see their reasoning, but part of me is a little worried the echoes get chewed up by dry air as they move NE. That's the only reason why I could see their logic. It's plenty cold on the coast if the moisture makes it towards Boston. It does look like a burst of precip may develop afte 12z but now we are fighting warming at the surface and aloft. We'll have to see how that first initial band does. Sometimes these WAA bands push further north when you have good WAA aloft. Thoughts?

[moneypitmike]

Surprised that the sky's overcast this morning.  It looks like there are some breaks starting to the southeast about 30 miles away (associated with the sunrise).....but to the SW, nothing but overcast.  I had expected more in the way of sun.

 

23.4/13

[OceanStWx]

Did we not just go through a situation where everyone was getting on BOX for not putting out advisories for a 20 minute freezing rain shower around the morning commute time?

 

I can't blame them for putting up a WWA after that situation and any chance for freezing drizzle or freezing showers.

 

Any amount of ice is cause for an advisory, so in both cases advisories are probably warranted.

[Tropopause_Fold]

I didn't see their reasoning, but part of me is a little worried the echoes get chewed up by dry air as they move NE. That's the only reason why I could see their logic. It's plenty cold on the coast if the moisture makes it towards Boston. It does look like a burst of precip may develop afte 12z but now we are fighting warming at the surface and aloft. We'll have to see how that first initial band does. Sometimes these WAA bands push further north when you have good WAA aloft. Thoughts?

yeah i didn't read their stuff either...just saw the map. considering these low end advisory issuances are more of a heads-up than anything, i feel like you'll have relatively similar conditions right to the shore during the early morning. it causes a perception issue in this case, i think. 

 

anyway, it does look like the thrust is more E than N at first so i could see a timing issue i suppose with relation to incoming easterly flow at the surface and warming aloft. but like you mention, seems these initial bands of precip tend to be a bit more "robust" than we expect them to be.

[dendrite]

SREF probs are pretty high in the interior for 1"+. The only low prob 4"+ area is around IZG. 1-2" looks like a safe bet as long as we don't have nucleation issues. The NAM cloud temps are still meh, but the GFS looked OK.

[OceanStWx]

Thats what I mean. Their snowmap has 1-2 here ranging 2-4 by you. Neither of which is happening

 

 

Man you are usually wildly optimistic but when bearish you're really bearish.

But you also have to know that they are really only calling for an inch for you and maybe 2" for MPM. But their map shows that if you don't focus on the higher numbers in the range, that's just how the program words it...same if they put 3.3" in the grid, it often comes out 3-7" of new snow.

I don't think their forecast is unreasonable.

 

 

This is why ranges can be a bad thing. There has to be a break point for each bin, so there will always be rounding errors when you are forecasting the low end of a range. The highest snowfall amount I can find in the BOX forecast is 2.9" out in GC. But that will read 2-4", along with 2.0". In that case you're probably better off looking at the graphical forecast images and adding up your snowfall forecast every 6 hours.

[OceanStWx]

That little -8C sliver at 925 mb should get the job done

 

You know, maybe I could argue for a few snowflakes if we can involve some sea salt nuclei. -8 C is not unheard of for snow growth then.

 

But meh...

[OceanStWx]

Model winds are too easterly in the beginning. This will probably be more of a 040 direction over the interior. Winds also will be very light even on the coast until after 12z tomorrow.

 

Guidance is so bad on that. I used a blend yesterday for speeds but had to manually force wind direction to NE for everything below 1500 feet. I mean no way IZG is a steady 130 degrees tomorrow (unless it's 13002KT for a minute).

[OceanStWx]

SREF probs are pretty high in the interior for 1"+. The only low prob 4"+ area is around IZG. 1-2" looks like a safe bet as long as we don't have nucleation issues. The NAM cloud temps are still meh, but the GFS looked OK.

 

For whatever reason the SREF mean is nearly 0.60" QPF there. I'm going to take the under. Definitely the highest in the area, when it is surrounded by 0.30-0.40".

 

[CT Rain]

You know, maybe I could argue for a few snowflakes if we can involve some sea salt nuclei. -8 C is not unheard of for snow growth then.

But meh...

Oh yeah that's what I meant. Sometimes even as low as -6 or -7 in low levels you can get some garbage heterogeneous nucleation and start spitting snow grains. Certainly nothing exciting but it's definitely easier to get ice in the cloud here near the coast with salt nuclei than in the Midwest.

I'd rather straight ZR over crappy snow grains.

[CT Rain]

For whatever reason the SREF mean is nearly 0.60" QPF there. I'm going to take the under. Definitely the highest in the area, when it is surrounded by 0.30-0.40".

Some of the ARW members are super juicy. The SREF probabilities are almost unusable since some of their non-hydrostatic members just go wild with vertical motion giving some bogus numbers.

[jamesnichols1989]

The NAM actually has much better lift in the snow growth zone with the frontal wave than the actual storm tomorrow.  Most members of the GFS ensembles have a hit for the frontal wave.  SREFs are getting juicier.

[dendrite]

For whatever reason the SREF mean is nearly 0.60" QPF there. I'm going to take the under. Definitely the highest in the area, when it is surrounded by 0.30-0.40".

Yeah...only mentioned it since they're usually the ones to "jackpot" in these setups...even if it's only about 3" in this case.

[OceanStWx]

Yeah...only mentioned it since they're usually the ones to "jackpot" in these setups...even if it's only about 3" in this case.

 

Saddest jackpot ever. If it's possible I think models overnight got drier in the snow growth zone.

[Damage In Tolland]

It looks like the thrust of best QPF in the beginning will be south, so you have a decent chance of 1-2.

Hope you're right but this looks awful to me. I still think it might not even begin as snow

[powderfreak]

This is why ranges can be a bad thing. There has to be a break point for each bin, so there will always be rounding errors when you are forecasting the low end of a range. The highest snowfall amount I can find in the BOX forecast is 2.9" out in GC. But that will read 2-4", along with 2.0". In that case you're probably better off looking at the graphical forecast images and adding up your snowfall forecast every 6 hours.

Yeah I learned that quickly back when the point and click first came out. I remember at the ski area we called or emailed BTV to inquire about a forecast for Mansfield that added up to like 8-16" when the map showed and text forecast had like 4-8". They told me to always use the graphical forecast, as just like you said, the ranges can be very mis-leading,

IIRC in that one they had a period of like 5" and another of 3" for the summit (which is usually one of the highest snowfall spots in their grids), but the ranges that came out were like 5-11" followed by a 3-7". So you see that, but the Snow Advisory was for 4-8", and it gets confusing sometimes. Since then I haven't paid much attention to the PC forecast snowfall ranges.

[CT Rain]

You can actually see the dry air north of the CT/MA border - 500mb seems to be a pretty good proxy for it.

 

Both the NAM and GFS show it so that could have some implications for areas along and north of the Pike with ptype. 

 

 

[CoastalWx]

Yeah I was using the 850-500 RH as a proxy which is similar to that graphic.

[Damage In Tolland]

You can actually see the dry air north of the CT/MA border - 500mb seems to be a pretty good proxy for it.

Both the NAM and GFS show it so that could have some implications for areas along and north of the Pike with ptype.

Meaning more or less?

[OceanStWx]

Yeah I was using the 850-500 RH as a proxy which is similar to that graphic.

 

It's nice that I can build a graphic specifically in the -12 to -18 layer here at work. I'll whip up some and post, but basically it shows the same thing.

[CT Rain]

It's nice that I can build a graphic specifically in the -12 to -18 layer here at work. I'll whip up some and post, but basically it shows the same thing.

 

Wish I had AWIPS  

[CT Rain]

Anyone else see this turning into like 1-2" for SW CT and little/nothing for the rest of us? 

 

SW CT winter rears its ugly head again?

[Damage In Tolland]

Anyone else see this turning into like 1-2" for SW CT and little/nothing for the rest of us?

SW CT winter rears its ugly head again?

Only if you buy the Nam. After it's performance the other night I don't

[dendrite]

Saddest jackpot ever. If it's possible I think models overnight got drier in the snow growth zone.

12z NAM is putrid. 12z sounding tomorrow is pretty close to just a PL/FZDZ/SG glop. It'll probably be one of those days where the ptype keeps flipping around based on lift. If the NAM is right we're probably looking at another disappointing C-1".

[OceanStWx]

Wish I had AWIPS

 

So when you get into the reds on these images you're talking 80% or greater RH in the -12 to -18 C layer. And solid yellow lines are omega in that layer. That bright purple over CNE? RH less than 20%. Awful. NAM is on the top, GFS on the bottom.