Pre Xmas storm

[Typhoon Tip]

Much stronger and more sprawling high to the north...classic drain over the top from the Canadian Praries.

 

It doesn't mean this run is correct though.

 

We may actually get out of this alive... ha.   I mean, the 12z NAM's FRH numbers heavily flag the inverted nature of the sounding, with colder T1's on average than the T2 layer, righ through Friday evening.  Fropa takes place over night, much for you are talking about (bold) the cold in the lowest 100 to 200 mb would almost certainly be hugely capped by warm air.  

 

Stepping back ... all the models indicate that although the 500mb thickness medium relaxes quite a bit starting now through Friday, the gradient remains such that it is less cross-thickness.  That may be why the BL stays relatively cool.  Also, this is a dry air warm-up initially, so that is useful to those that are worried about losing snow coverage  

 

So there are some interesting details conspiring to make what looks warm on the surface be perhaps not as warm.  

[Typhoon Tip]

euro.png

 

euro 2-m temp departures sunday afternoon - green is like -10F departure...those deep reds/brown are like +20F.

 

spring and mid-winter within 100 miles

 

Yeah, and just like in April ... when you see +PP arming into Maine, and you already have established dammed structure to the pressure contours ... nosing down into NE Mass...  you are not going to warm sector.  No way, no how, nope.  That is a negative static buoyancy that can't be removed, because cold air is stable underneath warm air.

 

If that sets up that way, I can almost guarantee a triple point moves E along the SC.   

[Tom MA wx]

Pretty sick temp gradient over southern new england on the Euro.  55 in south/central CT and 32 in northern MA

[Typhoon Tip]

I also recall over the last month and a half, a couple times where the SE ridge fought back, and the models progged a warm fropa here, and we busted cool with slate gray drippies.  

[SnowMan]

Pretty sick temp gradient over southern new england on the Euro.  55 in south/central CT and 32 in northern MA

If this verified that would be perfect!  It would be nice to see this trend continue...

[SnowMan]

If the temp is below freezing does that mean ice will automatically begin to accrete at a good rate or are other factors needed?

[Damage In Tolland]

Yeah, and just like in April ... when you see +PP arming into Maine, and you already have established dammed structure to the pressure contours ... nosing down into NE Mass... you are not going to warm sector. No way, no how, nope. That is a negative static buoyancy that can't be removed, because cold air is stable underneath warm air.

If that sets up that way, I can almost guarantee a triple point moves E along the SC.

Where can you see the boundary setting up? N NJ or NYC maybe?

[Whineminster]

:werd:

I'll never forget stepping out at 4am back in 08, literally sounded like a warzone with limbs snapping left and right all around me left me with a eerie feeling. Lost power for 7 days in that one 12/13-12/20.

Yeah my friend who lived in town at the time didn't have power for over two weeks. The people who owned my house before me said they had 30 trees across the driveway....i felt bad for you guys up here

[wx2fish]

If the temp is below freezing does that mean ice will automatically begin to accrete at a good rate or are other factors needed?

 

Depends on the precip rates too. If its pouring your gonna lose some down the drain especially close to freezing. Lighter rates are more efficient at ice accretion especially at marginal temps.

[Typhoon Tip]

If the temp is below freezing does that mean ice will automatically begin to accrete at a good rate or are other factors needed?

 

You need a constant source of cold.  When water change phase from liquid to solid, it releases a small amount of latent heat.  If you don't have a source of cold to drain in, that will tend to offset the icing for temps closer to 32F, and the temp may pop above freezing.  

 

In almost all icing storms, you have polar high anchored near-by and a NE wind, if not ageostrophic -N.   That feeds sub 32F DP air into the mix ...off-setting the latent heat release, and the icing can continue.  

 

Also, fall rate of the ZR can have an impact on accretion rates.  If it is falling very heavy, that will add some kinetic energy to the impact of the "hydro-meteoroids," and won't allow them to freeze before a lot of mass winds up on the ground.   The best way to get an "ice-storm", is a nice persistent upper end light rain at 29F, with a light N wind, and dense enough cloud deck that is thick enough to keep the mid day rather dim. 

[HoarfrostHubb]

Depends on the precip rates too. If its pouring your gonna lose some down the drain especially close to freezing. Lighter rates are more efficient at ice accretion especially at marginal temps.

I never really understood 2008... It was raining so hard, but we still got an inch plus of ice.  Will has tried to explain it to me, but it was such a weird event

[weathafella]

What's SnowMan going to do when his power goes and the 3G tower with it and he can't post for the next 4 events?

[N. OF PIKE]

John has been waiting for this since october -rev kev

[OceanStWx]

That is a Scooter fetish high branching in from Canada.

 

Boy that is a classic position for CAD. I dusted off the thesis and took a peek at the composite maps I made for SNE ice storms. All I can say is the players are in the right positions. That latest Euro with the baggy pressure field off Cape Cod, would mean most of the GYX CWA doesn't sniff 32 degrees this weekend until the cold fropa mixes us out.

 

[N. OF PIKE]

What's SnowMan going to do when his power goes and the 3G tower with it and he can't post for the next 4 events?

Im either gonna be in Bartlett sat pm thru mon am or N conway . Wonder where the better CAD is .

[SnowMan]

Depends on the precip rates too. If its pouring your gonna lose some down the drain especially close to freezing. Lighter rates are more efficient at ice accretion especially at marginal temps.

 

 

You need a constant source of cold.  When water change phase from liquid to solid, it releases a small amount of latent heat.  If you don't have a source of cold to drain in, that will tend to offset the icing for temps closer to 32F, and the temp may pop above freezing.  

 

In almost all icing storms, you have polar high anchored near-by and a NE wind, if not ageostrophic -N.   That feeds sub 32F DP air into the mix ...off-setting the latent heat release, and the icing can continue.  

 

Also, fall rate of the ZR can have an impact on accretion rates.  If it is falling very heavy, that will add some kinetic energy to the impact of the "hydro-meteoroids," and won't allow them to freeze before a lot of mass winds up on the ground.   The best way to get an "ice-storm", is a nice persistent upper end light rain at 29F, with a light N wind, and dense enough cloud deck that is thick enough to keep the mid day rather dim. 

Thanks for the explanations

[Tropopause_Fold]

euro ens are not quite as cold as the op (not surprising really). they do have a very small hint of some CAD over NE MA and into NH and have a really tightly packed thermal gradient over VT/NH...but at face value, as a mean, it doesn't look like they get the boundary quite as far south.

[OceanStWx]

I never really understood 2008... It was raining so hard, but we still got an inch plus of ice.  Will has tried to explain it to me, but it was such a weird event

 

When you have a +3 to +4 SD PWAT air mass and 3"+ QPF, you can lose a ton of it to run off and still manage an inch of ice.

 

[wx2fish]

I never really understood 2008... It was raining so hard, but we still got an inch plus of ice.  Will has tried to explain it to me, but it was such a weird event

 

What Tip just posted above is needed to for prolonged icing like 2008. The polar high is necessary to provide a constant source of lower dew points to offset latent heat release.

[ORH_wxman]

I never really understood 2008... It was raining so hard, but we still got an inch plus of ice.  Will has tried to explain it to me, but it was such a weird event

 

 

We still lost about 2 inches of rain down the drain in that one...but we were still able to accrete a lot of ice because we had a steady dry dewpoint source. It was actually advecting in at like 20 knots which is rare for ice storms. It really helped offset the latent heat of freezing and the heavier rates.

[SnowMan]

What's SnowMan going to do when his power goes and the 3G tower with it and he can't post for the next 4 events?

 and my name is Bryan...fwiw...probably not much though lol

[OceanStWx]

You need a constant source of cold.  When water change phase from liquid to solid, it releases a small amount of latent heat.  If you don't have a source of cold to drain in, that will tend to offset the icing for temps closer to 32F, and the temp may pop above freezing.  

 

In almost all icing storms, you have polar high anchored near-by and a NE wind, if not ageostrophic -N.   That feeds sub 32F DP air into the mix ...off-setting the latent heat release, and the icing can continue.  

 

Also, fall rate of the ZR can have an impact on accretion rates.  If it is falling very heavy, that will add some kinetic energy to the impact of the "hydro-meteoroids," and won't allow them to freeze before a lot of mass winds up on the ground.   The best way to get an "ice-storm", is a nice persistent upper end light rain at 29F, with a light N wind, and dense enough cloud deck that is thick enough to keep the mid day rather dim. 

 

2008 had some teens dew points draining into northeast MA from ME. Never really wavered either, as the low levels never became completely saturated up here.

 

[Tropopause_Fold]

i do hope that front can get down into MA so we have something to track. i don't wish a crippling ice storm on anyone...but also have no interest in 7 days of boredom.

[Damage In Tolland]

You can see how Friday could be the mildest day in SNE out of the whole deal. Pretty impressive trends should they hold

[tamarack]

I would welcome it at this point

 

So would I!  That saved the Farmington area in 1998 (though the resulting massive frozen-IP layer on roads lead to an awful spring-out.)

 

I never really understood 2008... It was raining so hard, but we still got an inch plus of ice.  Will has tried to explain it to me, but it was such a weird event

 

Neither do I.  MBY had roughly the same precip, some heavy (nearly 0.6" in 90 minutes) at the same surface temps, and dodged a bullet with only 0.2" accretion.  Maybe the cold layer was thinner, or the inversion stronger so the rain falling into that layer needed more cooling; maybe maybe...

 

Edit:  Reading the above, maybe we had higher dews on the inflow.

[dendrite]

Lalaland range for the NAM, but it keeps trending colder in the low levels as well.

[dryslot]

So would I!  That saved the Farmington area in 1998 (though the resulting massive frozen-IP layer on roads lead to an awful spring-out.)

 

I never really understood 2008... It was raining so hard, but we still got an inch plus of ice.  Will has tried to explain it to me, but it was such a weird event

 

Neither do I.  MBY had roughly the same precip, some heavy (nearly 0.6" in 90 minutes) at the same surface temps, and dodged a bullet with only 0.2" accretion.  Maybe the cold layer was thinner, or the inversion stronger so the rain falling into that layer needed more cooling; maybe maybe...

 

 

Would like to see the upper levels to continue to cool

[dryslot]

Lalaland range for the NAM, but it keeps trending colder in the low levels as well.

 

Yeah, Clown range but it looks like the signal is there on it as well

[Snow Bow]

Would rather have bare ground than an inch of ZR 3 or 4 days before Christmas. Starting to get that "wish I had a generator" feeling from the talk in here.

[powderfreak]

Lalaland range for the NAM, but it keeps trending colder in the low levels as well.

It brings like a 3-6" inch snowfall up here (0.5-0.75" QPF, but maybe some sleet contamination) prior to 18z Saturday....interesting.