12Z Guidance Discussion 12/21/10

[Zir0b]

I like the ridge being so strong upstream which argues for amplification but the timing of any phasing is critical. The Gem would not be that great for dc but would be great to the north though it's low does seem a little east of where I'd expect it from the 500h pattern. I haven;t seen the ukmet.

Here' s the UKMET

[Guest someguy]

Thanks for the info!

SBY 1.75" ALL SNOW

[Paweatherguy1]

I have seen plenty of posts for the eastern half of PA...but what exactly are QPF further back west in western PA, eastern OH, western NY? I'm assuming in the .50-.75 range? I'm also assuming there is a very sharp cut off.

[AlYourWxPal]

SBY 1.75" ALL SNOW

Thanks! If this happens I have no idea how I would get home Sunday night.

[winterymix]

Thanks for this....any thoughts on ratios? 15:1 seems likely for most of I95 from the look of it....no?

try 12:1

this is not an arctic airmass

[afvet89]

The UKMET, GGEM, and EURO, all show a major storm moving up the coast. With some differences in position of the low, I think todays 12z runs were very conclusive for a storm still 5 days away to significantly impact much of the mid atlantic and northeast. As for the GFS, well, whats there to say, wait till tonites run..

[H2Otown_WX]

Just for fun, does anyone have QPF for any of the CT stations?

[usedtobe]

wes

, it seems to me the euor at 12z is kind of close to the 0z euro ensemble mean at 120 and 144 ...

JMHO

I noticed that but still ma interested in the 12Z ensemble mean. Look at the ukmet, it phases but looks too far east to do us dc guys much good at least based on the 500h low position. I guess I'm more conservative than many here. If you change the relative speed of the two streams you change the result of any phasing.

[yoda]

HPC MAPS updated as of today for afternoon issuance

Day 4 -- http://www.hpc.ncep....ay=4&fcolor=wbg -- 1012 mb near NO

Day 5 -- http://www.hpc.ncep....ay=5&fcolor=wbg -- 992 mb off Cape Hatteras

Day 6 -- http://www.hpc.ncep....ay=6&fcolor=wbg -- low 970s 50 miles or so west of 40/70 BM

[Guest someguy]

try 12:1

this is not an arctic airmass

850 temps over RIC are -4c drop to -8c

and -8c are common all up and down the I-95 corridor

you sure about that?

[Baroclinic Zone]

Just for fun, does anyone have QPF for any of the CT stations?

Map was already posted in the thread.

[VAB1]

850 temps over RIC are -4c drop to -8c

and -8c are common all up and down the I-95 corridor

you sure about that?

Does ORF hold on for all snow or changeover.

[H2Otown_WX]

Map was already posted in the thread.

Oh I see it now. That's a pretty general map but QPF is pretty irrelevant at this point anyway.

[RUNNAWAYICEBERG]

try 12:1

this is not an arctic airmass

you should check again...its looks pretty cold to me. highs will be in the mid 20s max along I95 cities. of course the closer you get to the coast esp in SNE, there will be mixing and changeover issues.

[Organizing Low]

I have seen plenty of posts for the eastern half of PA...but what exactly are QPF further back west in western PA, eastern OH, western NY? I'm assuming in the .50-.75 range? I'm also assuming there is a very sharp cut off.

0.5 inch line right around pittsubrgh, about 30-40 miles east if the 0.75 line

all of NYS up north into canada is over 0.50 inches at minimum, majority over 0.75 inches.

looks like just buffalo/jamestown/niagra region in the 0.5 range.

[WinterWxLuvr]

Experts? Anybody?

I keep reading about the "slowing down", especially the Euro, and was wondering how this affects the track of the storm, it it occurs. If the low in the Atlantic is given more time to get out of the way? And how does this potential bombing out affect the eventual track of the low? Mainly the slowing down though. Net result on storm track?

[Paweatherguy1]

0.5 inch line right around pittsubrgh, about 30-40 miles east if the 0.75 line

all of NYS up north into canada is over 0.50 inches at minimum, majority over 0.75 inches.

Jeez....what a monster that storm must be to throw back QPF totals that far inland. I'd gladly take my .5 QPF with high winds and 15:1 ratios

[winterwarlock]

Why is the 12Z GFS wrong? Folks are real quick to just toss it's solution even though it has some support.

why? because its saying something that most people here dont want to believe. Just dont disagree with it because you want snow, the same stuff was being said with last weeks storm when the GFS caught on to it being ots

[Fozz]

Experts? Anybody?

I keep reading about the "slowing down", especially the Euro, and was wondering how this affects the track of the storm, it it occurs. If the low in the Atlantic is given more time to get out of the way? And how does this potential bombing out affect the eventual track of the low? Mainly the slowing down though. Net result on storm track?

If the storm slows down, it has more time to phase with the northern jet and become a blizzard.

If it moves faster, it does not phase, and we get much less snow, and may even go out to sea.

[Ridingtime]

When it came to storms last year (or any previous years really) was the Euro ever this consistent in showing a massive bomb this many runs in this time frame? And was it usually correct?

Basically, I don't remember the Euro ever showing such a massive bomb like this over and over. And I hope that is an indication that this could really happen.

[goldstar]

Slower usually means closer to the coast, as the storm runs into the block and slooooows down? Or by slower do we mean straight up that it will be later?

[Guest Patrick]

You're all going to laugh at me, but I am going to say this anyway.

In a Nina, the only model to follow is the ETA within about 6-12 hours of the storm's arrival. Reference mid 1990's

When it came to storms last year (or any previous years really) was the Euro ever this consistent in showing a massive bomb this many runs in this time frame? And was it usually correct?

Basically, I don't remember the Euro ever showing such a massive bomb like this over and over. And I hope that is an indication that this could really happen.

[weatherwonder]

If the storm slows down, it has more time to phase with the northern jet and become a blizzard.

If it moves faster, it does not phase, and we get much less snow, and may even go out to sea.

But is there such a thing as too slow? Like - so slow nothing happens? Just saw an 18 hour difference in start times between last night's models and today's model runs. That's a huge difference and what is slowing the development?

[Ridingtime]

You're all going to laugh at me, but I am going to say this anyway.

In a Nina, the only model to follow is the ETA within about 6-12 hours of the storm's arrival. Reference mid 1990's

So you're basically saying you're not taking into any account any model whatsoever except the ETA 6-12 hrs before the storm?

[hobbes9]

So you're basically saying you're not taking into any account any model whatsoever except the ETA 6-12 hrs before the storm?

And wouldn't most models have picked up on things 6-12 hours before a storm? I'd like to think that some of the model programming has changed for the better in the last fifteen years?

[Terpeast]

When do the Euro ensembles usually come out?

[yoda]

When do the Euro ensembles usually come out?

Around 330

[dg12x]

When do the Euro ensembles usually come out?

Already rolling out to 42 hours..(I only have some rough precip/temp maps through work though).

[Ji]

you guys may laugh but I am not liking the JMA not being in the same camp as the EURO. Uusally the JMA goes nuts with this stuff. The fact that the JMA never showed a storm last week at all while the others did at one point is alarming. The JMA is showing an improved solution but its nowhere near the EURO

[Ji]

you know...if the EURO showed this solution for a midwest/lake cutter bomb, it would never waver. It only seems to waver for I95 snowstorms