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Wintry January 8-9, 2018 Ice threat

I don’t even want an ice storm, but i just don’t quite get how temps can rise so much with temps around 28 and dewpoints bear zero.
 
Somebody look at a sounding and see if the cold dome is deep or very shallow. With the high moving WELL offshore, pumping in air off of the Atlantic, the low pushing air in from the SW, and the precip taking forever to get in and lock in the wedge, it may very well turn out to be nothing more than a nuisance event. That said, the globals absolutely will erode the cold dome too quickly and have fun with bogus SLP tracks at this range. The high MUST stay in place a bit longer and/or the precip needs to move in faster. Ticks slower with the preip are not what we want to see.
 
As has been mentioned previously, it comes down to the strength and positioning of the HP ... if the models have a good grasp of it moving away that quickly, I can see the quick warm-up. However, experience tells many of us that traditionally wedges are difficult to erode. But if the HP is moving away, I can see the warm overtaking the cold relatively quickly. Still a lot to watch!
 
One other thing to note, Grit mentioned it on the other board, but if precipitation arrives early enough and locks in the wedge, the development of a meso high in VA is a definite possibility. This would act to maintain a NE component to the low level flow and keep the wedging going for parts of the Piedmont. Obviously, these are details that require much closer leads to ascertain. Right now, I'd give this about a 25% chance of being something more than a little front end icing. Still have a bit of work to do.
 
NorthGaWinter4 said:
I don’t even want an ice storm, but i just don’t quite get how temps can rise so much with temps around 28 and dewpoints bear zero.
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Depends on where the low that Goofy was showing decides to go...and how strong it is. Thru Ga and the waa screams in and it's rain in a hurry. Down in Fla and it's Tony's sleet storm :)
 
Rain Cold said:
One other thing to note, Grit mentioned it on the other board, but if precipitation arrives early enough and locks in the wedge, the development of a meso high in VA is a definite possibility. This would act to maintain a NE component to the low level flow and keep the wedging going for parts of the Piedmont. Obviously, these are details that require much closer leads to ascertain. Right now, I'd give this about a 25% chance of being something more than a little front end icing. Still have a bit of work to do.
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waiting on Robert as he is one of the best with cad storms
 
yep models seem to always miss cad events. The event generally does more than model shows
 
deltadog03 said:
The high leaving quicky won't help the cad process at all.
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This is not your average high or cold! But it mostly will be dependent on how quickly moisture can arrive. IMO, get moderate precip in any time before 7,8,9 AM, and it will be much worse! If precip arrives at noon or later, cold rain for everybody!
 
If that HP is not around WAA from the incoming shortwave will quickly flush out the trapped cold air period... It will take more time of course the further E you are but eventually it WAA will win out... Again this is IF the HP is transient as the models are currently showing... Front end ice then to rain


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If we can get precip in around 11:30 PM Sunday it's game on. Southwesterly winds will certainly take over at some point but it won't matter if there's already 1/4-1/2 inch of ice on everything. The damage will already be done. 00z runs tomorrow night should be telling as far as precip timing goes
 
Rain Cold said:
One other thing to note, Grit mentioned it on the other board, but if precipitation arrives early enough and locks in the wedge, the development of a meso high in VA is a definite possibility. This would act to maintain a NE component to the low level flow and keep the wedging going for parts of the Piedmont. Obviously, these are details that require much closer leads to ascertain. Right now, I'd give this about a 25% chance of being something more than a little front end icing. Still have a bit of work to do.
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Who's this grit character!?
Just have to watch trends, if precip arrives late morning or afternoon, its game over!
 
I’m having a hard time remembering a CAD ice storm set up on the heels of such a severe and lengthy artic outbreak.

FFC afternoon discussion said that temps and dew points came in a few degrees colder on 12z runs for sun night/Monday.
 
Local met says we have to outsmart the models because they never handle CAD even remotely well. He's anticipating icy conditions through the early morning hours maybe up until 10-11am. He reinforced the fact that a lot of our wintry events come on the heels of a a pattern change with southwesterly winds bringing moisture in. He's clearly seen this movie before
 
Storm5 said:
Not much eps support fwiw
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we had a lot of ensemble support 4-5 days out on our last 2 events and we all know how those ended up for most of us. This ones certainly not set in stone either way
 
Just my $ .02 wait for this high res Nam tomorrow evening. It will handle the cad and the dew points and erosion much better than the globals will. So far theres def potential there for early morning ice in cad regions and changing over to rain by mid day if precip starts early enough.
No way to tell based on the globals as they all have different start times with precip and all have there own ideas of how fast the cold gets eroded.
 
Jimmy Hypocracy said:
we had a lot of ensemble support 4-5 days out on our last 2 events and we all know how those ended up for most of us. This ones certainly not set in stone either way
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Haha yeah a foot of snow in parts of Alabama and Georgia and the last system did ok as well. 10 inch plus amounts along the Carolina coasts and some 6 inch amounts in NC.

This at best is a minor I've to rain threat . With the high moving out and the low moving in the blasting WAA will win out
 
Rain Cold said:
One other thing to note, Grit mentioned it on the other board, but if precipitation arrives early enough and locks in the wedge, the development of a meso high in VA is a definite possibility. This would act to maintain a NE component to the low level flow and keep the wedging going for parts of the Piedmont. Obviously, these are details that require much closer leads to ascertain. Right now, I'd give this about a 25% chance of being something more than a little front end icing. Still have a bit of work to do.
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I was thinking about this earlier and didn't know if a meso high was similar to an in-situ type scenario. From what I remember a meso high is a result of the lower dewpoints and precip falling at a good rate locking in the cold. Pretty sure we saw this a few years ago if I'm not mistaken.
 
FWIW, Silly KCAE has already given me 50% zr then to rain.
 
Storm5 said:
Haha yeah a foot of snow in parts of Alabama and Georgia and the last system did ok as well. 10 inch plus amounts along the Carolina coasts and some 6 inch amounts in NC.

This at best is a minor I've to rain threat . With the high moving out and the low moving in the blasting WAA will win out
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Lots of ensembles were actually on board with the New Years look 4-5 days but ok. The New Years suppressed whiff ended up being a historic bomb a few days later.. Although I do agree this next one does look like mostly a rainer
 
FFC honking ICE STORM...

Area Forecast Discussion
National Weather Service Peachtree City GA
254 PM EST Thu Jan 4 2018



.SHORT TERM /Tonight through Friday Night/...
No major forecast concerns in the short term period. 12Z model
guidance agree well with each another. Gusty winds will diminish
significantly after sunset but with sustained winds of 5 to 15 mph
overnight, still expect wind chill criteria to be met at times over
north GA tonight and Friday morning. Compared to original wind chill
advisory, only some tweaks to start and end times and removed a few
counties.

SNELSON


.LONG TERM /Saturday through Thursday/...
A few changes were needed to the weather grids for Sunday night into
early Morning, mainly for p-type. In addition, adjusted the MaxT
grids for Monday, especially in areas contained within the wedge.

A wintry mix is still possible Sunday night into early Monday
morning. A strong wedge will be in place across much of northern GA
during this time period. Surface temperatures will be at or just
below freezing within the wedge, and with warmer temperatures aloft,
the potential for freezing rain will increase. It is still too early
to definitively delineate exactly where any wintry mix will occur
and any accumulations.

Models tend to want to wipe the wedge out a lot sooner than actually
occurs. This is forecasted to be a pretty strong wedge...so am
concerned about the high temperatures on Monday. Have adjusted
values downward a few degrees within the wedged area, and values
could go even lower if the surface low to the south and/or
precipitation ends up re-enforcing the cold air in place.

Interests across northern GA, including the Atlanta metro should
continue to monitor later forecasts. The forecast will likely
change, it is still 4-5 days out. Any small shift in a low pressure
track...or even timing...could vastly affect the forecast.
 
Storm5 said:
Haha yeah a foot of snow in parts of Alabama and Georgia and the last system did ok as well. 10 inch plus amounts along the Carolina coasts and some 6 inch amounts in NC.

This at best is a minor I've to rain threat . With the high moving out and the low moving in the blasting WAA will win out
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Right. Don't fool yourselves into thinking it won't. I live in a CAD area in NC and I've gone from 17 degrees at 6:00 in the morning to 52 degrees and raining by 11:30. Couldn't believe it.
 
BPATL said:
FFC honking ICE STORM...

Area Forecast Discussion
National Weather Service Peachtree City GA
254 PM EST Thu Jan 4 2018



.SHORT TERM /Tonight through Friday Night/...
No major forecast concerns in the short term period. 12Z model
guidance agree well with each another. Gusty winds will diminish
significantly after sunset but with sustained winds of 5 to 15 mph
overnight, still expect wind chill criteria to be met at times over
north GA tonight and Friday morning. Compared to original wind chill
advisory, only some tweaks to start and end times and removed a few
counties.

SNELSON


.LONG TERM /Saturday through Thursday/...
A few changes were needed to the weather grids for Sunday night into
early Morning, mainly for p-type. In addition, adjusted the MaxT
grids for Monday, especially in areas contained within the wedge.

A wintry mix is still possible Sunday night into early Monday
morning. A strong wedge will be in place across much of northern GA
during this time period. Surface temperatures will be at or just
below freezing within the wedge, and with warmer temperatures aloft,
the potential for freezing rain will increase. It is still too early
to definitively delineate exactly where any wintry mix will occur
and any accumulations.

Models tend to want to wipe the wedge out a lot sooner than actually
occurs. This is forecasted to be a pretty strong wedge...so am
concerned about the high temperatures on Monday. Have adjusted
values downward a few degrees within the wedged area, and values
could go even lower if the surface low to the south and/or
precipitation ends up re-enforcing the cold air in place.

Interests across northern GA, including the Atlanta metro should
continue to monitor later forecasts. The forecast will likely
change, it is still 4-5 days out. Any small shift in a low pressure
track...or even timing...could vastly affect the forecast.
Click to expand...
How is that honking Ice storm ?

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mrdaddyman said:
Right. Don't fool yourselves into thinking it won't. I live in a CAD area in NC and I've gone from 17 degrees at 6:00 in the morning to 52 degrees and raining by 11:30. Couldn't believe it.
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I've seen it start as ZR and forecast to hit 50 and had crippling ice storm at 31 degrees.
 
Storm5 said:
How is that honking Ice storm ?

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I'd say that is bold for FFC, from what I've heard on here! Everyone says how conservative they are and never say there's going to be snow or ice. So them saying it at about 4 days out is bold?
 
Blue_Ridge_Escarpment said:
Basically they said as is, it’s a nice front end ice but models suck at CAD and common sense will need to be added to forecasting.
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I got that , which is what's been said here all morning . What I didn't get is a feeling they are worried about an ice storm . Maybe I need to go read it again

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Tarheel1 said:
I've seen it start as ZR and forecast to hit 50 and had crippling ice storm at 31 degrees.
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No doubt. But my point is that folks are saying that the cold air cannot be eroded that fast. It can because I've seen it first hand.
 
Storm5 said:
I got that , which is what's been said here all morning . What I didn't get is a feeling they are worried about an ice storm . Maybe I need to go read it again

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I’m not sure if worried is the best word but they are definitely sounding the alarm that the models are probably not right with temps, hence the ticking down with temps in their CWA
 
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