December 6-7: Rainy Frontal Passage or a Wintry Wave?

[CT Rain]

I love that method of snowfall forecasting.  It's probably too complex for the average weather consumer, but I wish all forecasts were more probability based like that.  So when there is a big bust on either side, say 0" or 10", people can't just complain that forecasters are terrible.  There would be more understanding of the range of possibilities.

 

I can't put it on air but I use it for blogs/social media. 

 

The snowfall map I posted before we added a part on there for "forecast confidence" as a way to explicitly express uncertainty. 

[eduggs]

ALB  39 32 3117G22

Been stuck at 39 for a while.  Surface actually warming a little where I am outside of Albany.  But the dews are gradually ticking downward.  Valleys sucks for snowfall.  I bet the capital region struggles to reach freezing all day while everyone above 500ft to the east and southeast are 30F and snowing.  In the elevated western part of Albany county, it's already approaching freezing.

[SnowMan]

Nice disco Tippy..Sounds like a couple to several inches for all!!

Wait...I thought a couple was the same as several...if so you are being repetitive...

[CoastalWx]

Here is a reason to be bullish laid out from an instability and fronto standpoint.

 

 

 

[CoastalWx]

Here is a reason to be bullish laid out from an instability and fronto standpoint.

 

eta_18_700.gif

 

SREF_front_mpv_mean1__f021.gif

 

SREF_SNOWRATE_1INCH__f021.gif

 

If you're near and north of I-90 and esp higher el. That doesn't mean nobody else can see it..but outlining highest prob of overachieving.

[Typhoon Tip]

Here is a reason to be bullish laid out from an instability and fronto standpoint.

 

eta_18_700.gif

 

SREF_front_mpv_mean1__f021.gif

 

SREF_SNOWRATE_1INCH__f021.gif

 

Interesting, Scott -- I came to the same conclusion of these products just by observing the looping IR imagines (I mentioned in the post above).  The axis of lift/details on the loop has SNE in the cross-hairs, so these products are a perfect extrapolation off the now-cast sat obs... 

[CT Rain]

If you're near and north of I-90 and esp higher el. That doesn't mean nobody else can see it..but outlining highest prob of overachieving.

 

Seems to me that even lower elevations may cool the boundary layer pretty quickly... may turn out being more of an issue of sleet vs snow? 

[Typhoon Tip]

I think an argument can be made for going both bullish or bearish on this system....you make a good bullish argument. The bears can point to the parallel flow with the marginal pesky warm layer betweem 700-800mb as being a limiting factor and taking too long to get washed out. Big omega overruning the front can overcome that though and certainly that is where a lot of the uncertainty lies.

 

 

That's a good point!   I did mention yesterday that I wasn't certain if an elevated warm layer were present ( ) which can provide for an obnoxiously tall sleet column.  Can one imagine sleeting through 9,000 ft of atmosphere!  A- nnoying...

 

That said, it could also assist a bit of frontogenic and meso band not well modeled just on the NW side of the elevated thermal packing.  That would be sweet! 

 

But yeah, like I said I'm willing to compromise with consensus and go 3-5"...I'll say 3" down between the Pike and typical SC butt-sore zone(s), and 5" near FIT. 

[NorEastermass128]

If you're near and north of I-90 and esp higher el. That doesn't mean nobody else can see it..but outlining highest prob of overachieving.

 

Is 150' here classified as 'high terrain' for the coastal plain?  I think we'll manage to get the grass covered here, may even get to scrape the driveway tomorrow morning too.

[Stash]

Feels like its getting colder down in ALB city today.  Considering what it has to work with, its not a bad city for snowfall with a 60-something average.  Other areas of the "Capital Region" (dislike that term geophysically, but its fine geo-politically) do better, even in non-elevated areas.  When I lived out in Rotterdam, I had enough rotting LE snowshowers to nickle and dime my average considerably higher than Albany itself.  That said, despite its run of bad luck in recent years, its not a bad area for snow.

Been stuck at 39 for a while.  Surface actually warming a little where I am outside of Albany.  But the dews are gradually ticking downward.  Valleys sucks for snowfall.  I bet the capital region struggles to reach freezing all day while everyone above 500ft to the east and southeast are 30F and snowing.  In the elevated western part of Albany county, it's already approaching freezing.

[eduggs]

Roasting up to 42F outside of ALB.  But near 850mb is cooling off nicely.  So far looks well modeled.  I'm thinking this one overperforms NW of and maybe along the I-84 - I-90 corridor.  There should be some pretty intense lift for a few hours.  That should be enough to cool the marginal column.  Marginal temps and sneaky warm layers stink with weak lift.  But that's not what we're dealing with here.  Look at the radar/satellite.  And the cold front is already south of Long Island.  The cold air doesn't even have to come very far.

 

Personally I'd rather see this setup a little further NW for my area, but I think the best rates stay SW and then SE of ALB.  Lift also looks to weaken overnight as the shield slides SE... that might hurt areas in E and SE SNE as the shield dries up before the cold comes.

[CoastalWx]

Seems to me that even lower elevations may cool the boundary layer pretty quickly... may turn out being more of an issue of sleet vs snow? 

 

Oh yeah it definitely will..just mean that higher elevations will obviously have cooler srfc temps and may help boost totals. This may be one of those deals where Ray and Will perhaps have similar snow totals..maybe off by an inch or whatever.

[CoastalWx]

Is 150' here classified as 'high terrain' for the coastal plain?  I think we'll manage to get the grass covered here, may even get to scrape the driveway tomorrow morning too.

 

Yeah see my earlier post. This may be a decent event for you "lower" elevation people in nrn Mass.

 

And it very well could extend south into nrn CT.

[eduggs]

Feels like its getting colder down in ALB city today.  Considering what it has to work with, its not a bad city for snowfall with a 60-something average.  Other areas of the "Capital Region" (dislike that term geophysically, but its fine geo-politically) do better, even in non-elevated areas.  When I lived out in Rotterdam, I had enough rotting LE snowshowers to nickle and dime my average considerably higher than Albany itself.  That said, despite its run of bad luck in recent years, its not a bad area for snow.

It's not bad at all in an absolute sense.  But it's the warmest and least snowy city in NYS, basically north of Kingston/Hudson.  There's more snow in every direction except south.  Even the airport is noticably colder than downtown.  Rotting LE is fun.  I guess because it's an unexpected bonus.  I can totally see how places just NW get in on that a bit.

[NorEastermass128]

Yeah see my earlier post. This may be a decent event for you "lower" elevation people in nrn Mass.

 

And it very well could extend south into nrn CT.

 

IF it performs better than thought, I'm glad people will be surprised by a couple inches on a Saturday morning, rather than a weekday morning.  Timing definitely helps out forecasters.

[CoastalWx]

IF it performs better than thought, I'm glad people will be surprised by a couple inches on a Saturday morning, rather than a weekday morning.  Timing definitely helps out forecasters.

 

Like Will said...two hours on either side of changeover timing is everything. When lift is one of the factors that helps decide when a flip to snow is in order..it's best to not go balls to the wall...although I do like some of the signals up that way.

[snowgeek]

Been stuck at 39 for a while.  Surface actually warming a little where I am outside of Albany.  But the dews are gradually ticking downward.  Valleys sucks for snowfall.  I bet the capital region struggles to reach freezing all day while everyone above 500ft to the east and southeast are 30F and snowing.  In the elevated western part of Albany county, it's already approaching freezing.

I'm actually more worried about missing the best forcing to the south.  My temp worries have faded.  Dewpoint down to 31F with a healthy NW wind (10-15 mph).  I'm in Voorheesville right now (elevation 400 ft.)

 

I just read your other post and you basically said this too.....so I agree.

[eduggs]

I'm actually more worried about missing the best forcing to the south.  My temp worries have faded.  Dewpoint down to 31F with a healthy NW wind (10-15 mph).  I'm in Voorheesville right now (elevation 400 ft.)

I am too.  Consensus puts the best stuff south of here.  But that might still be pretty good.  These things never follow the models exactly.  Banding could set up north or south of us.  Will be fun to follow the radar today and then enjoy some falling snow for a change.

 

Regarding temp concerns... I think it will snow, but it might be 33F while up the escarpment it's 28F.  Last week's 1.5" felt like a lot more because it fell with temps in the mid and upper 20s.  That's where elevation really helps out.  The whole feel of a snow event is changed when temps are comfortable below freezing.  If we get into heavier bands, it probably won't matter much.  Voorheesville is usually a degree or two cooler than further east, down in the valley.

[CoastalWx]

I'm staying modest and hoping C-1" for my hood. I'm never a fan of these trickle down temp setups.....only if the lift is sufficient would I become more bullish. That still may happen, but a little unsure locally. Different story to my north though. I do allow for the possibility of more.

[Tropopause_Fold]

I'm staying modest and hoping C-1" for my hood. I'm never a fan of these trickle down temp setups.....only if the lift is sufficient would I become more bullish. That still may happen, but a little unsure locally. Different story to my north though. I do allow for the possibility of more.

i'm with ya. for whatever that's worth.

[snowgeek]

I am too.  Consensus puts the best stuff south of here.  But that might still be pretty good.  These things never follow the models exactly.  Banding could set up north or south of us.  Will be fun to follow the radar today and then enjoy some falling snow for a change.

 

Regarding temp concerns... I think it will snow, but it might be 33F while up the escarpment it's 28F.  Last week's 1.5" felt like a lot more because it fell with temps in the mid and upper 20s.  That's where elevation really helps out.  The whole feel of a snow event is changed when temps are comfortable below freezing.  If we get into heavier bands, it probably won't matter much.  Voorheesville is usually a degree or two cooler than further east, down in the valley.

I live in Slingerlands at 225', so not quite as good as Voorheesville.  The best forcing does seem to often end up further north than forecast...not sure this situation applies.  Will be fun to watch the radar tonight.  Does seem to be bust potential either way.

[CT Rain]

I'm staying modest and hoping C-1" for my hood. I'm never a fan of these trickle down temp setups.....only if the lift is sufficient would I become more bullish. That still may happen, but a little unsure locally. Different story to my north though. I do allow for the possibility of more.

 

 

i'm with ya. for whatever that's worth.

 

The only thing I sort of "like" about this event compared to the usual wait for the CAA is that last night's fropa and this upper level disturbance are pretty far apart temporally and spatially. Almost like this disturbance is a separate kind of system and not your typical anafront nonsense. 

[CT Rain]

Euro seems to have held serve. Not much of a difference... maybe a smidge cooler for western Mass. 

[N. OF PIKE]

I'm really liking the amount of juice this system seems to have on radar over Ohio Valley and that the cold air is seeping in already.....we need that burst of Omega (likely to cool that warm nose aloft) but it doesn't seem far fetched and the Route 2 corridor over to Ray looks in line for a solid 3-5 inches.

 

I think Bos Burbs could get the same if things work out well with the OMEGA burst and hvy rates probably a 33F paste along 128 corridor starting around 11pm.

[Tropopause_Fold]

The only thing I sort of "like" about this event compared to the usual wait for the CAA is that last night's fropa and this upper level disturbance are pretty far apart temporally and spatially. Almost like this disturbance is a separate kind of system and not your typical anafront nonsense. 

i don't think i would change much from the map you posted, if i were making one. 

[CoastalWx]

The only thing I sort of "like" about this event compared to the usual wait for the CAA is that last night's fropa and this upper level disturbance are pretty far apart temporally and spatially. Almost like this disturbance is a separate kind of system and not your typical anafront nonsense. 

 

Don't get me wrong...I like it...especially in the areas I spoke about...I'm just unsure how low level temps will shake in my area. I definitely haven't been talking about this because I'm down on it...lol. Those frontogenesis areas and -EPV layers above it will allow for someone to do well. I feel bullish in NE MA to close to BOS.. There will be a latitudinal gradient with this independent of elevation.

[CT Rain]

i don't think i would change much from the map you posted, if i were making one. 

 

 

Don't get me wrong...I like it...especially in the areas I spoke about...I'm just unsure how low level temps will shake in my area. I definitely haven't been talking about this because I'm down on it...lol. Those frontogenesis areas and -EPV layers above it will allow for someone to do well. I feel bullish in NE MA to close to BOS.. There will be a latitudinal gradient with this independent of elevation.

 

Yeah I think that map is probably the prudent way to go. To be honest, we probably won't know much more until almost 00z when we can look at the RAOBS.

 

I do agree there is some potential for a 6" jackpot somewhere... I'm just not sure where that is. 

[N. OF PIKE]

Don't get me wrong...I like it...especially in the areas I spoke about...I'm just unsure how low level temps will shake in my area. I definitely haven't been talking about this because I'm down on it...lol. Those frontogenesis areas and -EPV layers above it will allow for someone to do well. I feel bullish in NE MA to close to BOS.. There will be a latitudinal gradient with this independent of elevation.

Scott looking at What has fallen in SE Illinois as well as the VERY localized narrow stripe of good accums across Indiana and Ohio do you think that this band is going to be similar in SNE /S. CNE  as far as sharp cut offs on both northern and southern ends.....and we really won't know where that will set up exactly....(when a 20 mile shift can be difference between 4 inches and a inch.

 

I guess my point and this is what I was trying to emphasize is that I think there is potentially a much bigger "surprise potential" tonite for some areas to get screwed and others to get "much more". I mean to a degree....i.e someone near boston and just SW or so could squeak out a 4-5 while someone near Ray gets 1.5 ....it just depends on how fast the BL and warm nose cools and/or  WRT to getting heavy precip (and it's location). I think most everyone should be on their toes tonite for between 1-5 inches of snow with 4-8 possible from Litchfield hills up thru KPSF even if currently best spot looks to be Route 2 area W-E.

 

nice strip of 5-7 inches from Tulsa over to SE MO and then some spot 10 inch amounts in SE Illiinois....prob over to parts of Indiana later nice

[Cold Miser]

currently 48f.  Not much change.

[SnowlieSnowstormson]

Here comes the front!