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Wintry 1/20 - 1/23 Winter Storm

Last 4 runs of the EPS...fairly confidant there will be an event but it will be further NW than even where it's modeled today. You can see the atlantic ridge pushing west....the SLP trend for another view of that. We've seen this how many times over the years...atlantic ridge trending stronger all the way up to the event. Probably why GFS is struggling with this...it's the worst at modeling the atlantic ridge at day 4-5.


EPS_trend1.gifEPS_trend2.gif
 
I should have noted...this to me is probably going to be a further SE (NC/VA) event than what happened yesterday....I think another ice storm is in the cards.

Edit: I may eat that "further SE" comment....this could end up in Cleveland. But we would have to really suck for that to happen...
 
From KCHS ..
They've been discussing the potential in the Low country for a couple days now..

.LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/...
A baroclinic zone will exist along the SC/GA coast Thursday
night. A strong upper shortwave approaching from the west will
tighten the gradient and spur coastal cyclogenesis. Meanwhile,
near the surface, cold air advection will occur as high pressure
wedges down the Eastern Seaboard.

The thermal profiles of all of the medium range models indicate
the potential for wintry precipitation across all or part of the
forecast area at some point from late Thursday night through
Saturday morning. There has been drastic run-to-run
inconsistency between the global models which has resulted in
a low confidence forecast. At least the 00Z runs are showing
some broad consistency regarding the timing of the greatest QPF,
with Friday and Friday night being the most active. All models
are showing dry conditions beyond midday Saturday so we have
followed suit and removed PoPs beyond 18Z Saturday.

The beginning of the p-type concerns is late Thursday night.
Fairly strong moist isentropic ascent along the coastal front
will continue to produce light to moderate rain overnight.
Meanwhile, strong cold air advection will be occurring, with
surface temps steadily dropping overnight. Model soundings
indicate the potential for a few hours of freezing rain across
inland SC just before daybreak Friday.

Surface low pressure is forecast to develop somewhere along the
Southeast coast on Friday. Moisture and forcing will overspread
the area during the day, aided by strengthening right entrance
region jet divergence. Fairly extensive precipitation is
forecast on Friday. The atmosphere is forecast to steadily cool
during the day Friday. Model soundings show a pretty wide range
of p-types, with some indications that a portion of the area
will see freezing rain for much of Friday while others show a
more rapid cooling trend and a snow profile. The NBM continues
to show up to 0.10" of freezing rain and up to an inch of snow
through 12Z Saturday, the greatest accumulations across inland
SC. It does seem most likely that if wintry precip occurs, it
will probably be a mix. Given the extreme uncertainty with this
event, we have kept things simple with respect to p-type and are
depicting rain and/or snow in many areas from late Thursday
night through Saturday morning.

All of the 00Z guidance shows precipitation ending by midday
Saturday at the latest. The GFS is quite aggressive at scouring
out the moisture early Friday evening while the ECMWF and CMC
are much slower with the precip ending. So, not only is the
p-type in question, but the duration and thus accumulation
potential are also quite uncertain at this juncture.
 
We actually need a little Atlantic ridging to help but too much....well you know. You can clearly see the GEFS is weaker than EPS. The EPS usually handles the Atlantic ridge much better....GFS will be playing catch up. Canadian looks to be close to the Euro.

EPSGEFS.gif
 
Here's the latest blend of models from Pivotal.
snowfall_acc.us_ma.png

framexp_acc.us_ma.png
 
Stormdoc said:
View attachment 107194
Look at those SSTs over the Gulf Stream. Lots of warm water to tap for moisture and also set up a strong baroclinic zone. My only fear with it here in Raleigh is the potential for warmer upper level mixing, as demonstrated by last nights Euro run. We definitely need a more positive tilt to this thing so we get more west to east winds. With the amount of energy though someone is going to get pounded.
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These SSTs is also why I would favor a close to the coastline track with the airmass that is gonna be in place over land… strong thermal gradient and an excellent baroclinic zone… it’s why eastern Carolinas could mix a good bit on the front of the storm
 
My thoughts on this is I think a winter storm of some kind is very likely to occur in the Carolinas and Georgia. How that setup progresses at H5 is really the biggest thing as to what we all end up getting precip wise. To me if you’re along the I20 and I95 corridor, this has the progression to be an ice storm. Now usually sleet saves the western Carolinas from the scary ZR maps because CAD gets under modeled which is likely the case in this setup around our way but CAD starts having much less influence the further you get from typical CAD areas. It can help get 2m temps colder than advertised especially through the pee dee and I20 but the upper levels are at any LP track’s will. I could definitely see more ZR especially towards the coast. But this is how the western Carolinas and particularly the 85 corridor through NC, the upstate, and NE Georgia get their monster snows.
 
KyloG said:
I should have noted...this to me is probably going to be a further SE (NC/VA) event than what happened yesterday....I think another ice storm is in the cards.

Edit: I may eat that "further SE" comment....this could end up in Cleveland. But we would have to really suck for that to happen...
Click to expand...
Given the modeled temps across all the ensembles at the moment this event at least seems to remain all frozen for most unlike yesterday. That’s a starting point
 
Can anyone more or less tell me what the modeled surface LP track is on the 06z GFS? Does it move up offshore. Looked to be through the NC sound area maybe?
 
What we should anticipate is this coming more North and West but the big question is how much? Interaction with the Northern stream will help the QPF and keeping the cold locked in, but with that said, there will be a warm nose for a lot of us just like this last storm. Modeling will vary for the next 3 days so don't get too excited nor too depressed with what you see as it will change. None of the models did a great job this weekend but I think we are getting to more of a model consensus earlier with this one so far. I will reserve judgement on this one until the 6Z runs on Thursday, but that is just me
 
06z Euro Op run was actually more 'suppressive' than the 00z run. The wave in the SW comes out, but additional shortwave energy is getting dropped into the SW in a psuedo split flow. On the 06z, the main wave thru Iowa is more ahead / on top of the wave over Northern Mexico, and you can see the heights are a touch south thru E VA/NC. Anyway, fine line here between not much of an event and a big storm that cuts inland. @BHS1975 duly noted phasing last night...I think the winning formula to get more folks east of the mountains involved with snow is for the wave complex to drop down positive tilt for a long time, then have a late phase between the 2 streams. That gets the arctic front to the coast quicker, with colder temps aloft as the storm cranks up due to the heights crashing associated with phasing.

Ep75SQs.gif
 
Novice here, but maybe some of you who are more experienced can chime in. Obviously, we
are still fairly far out from the event and much can change, but based on the model handling on the storm yesterday, how do you feel about the chances of a potentially more potent storm next weekend?


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griteater said:
06z Euro Op run was actually more 'suppressive' than the 00z run. The wave in the SW comes out, but additional shortwave energy is getting dropped into the SW in a psuedo split flow. On the 06z, the main wave thru Iowa is more ahead / on top of the wave over Northern Mexico, and you can see the heights are a touch south thru E VA/NC. Anyway, fine line here between not much of an event and a big storm that cuts inland. @BHS1975 duly noted phasing last night...I think the winning formula to get more folks east of the mountains involved with snow is for the wave complex to drop down positive tilt for a long time, then have a late phase between the 2 streams. That gets the arctic front to the coast quicker, with colder temps aloft as the storm cranks up due to the heights crashing associated with phasing.

Ep75SQs.gif
Click to expand...
Great analysis grit! Do you think this gets resolved on the models in the next 24-36hrs or so? There seems to be good agreement on the storm signal and has for days just not on the track/intensity fully yet. I know resolving p-types and their locations will likely be another 72hrs or so.
 
njbarrineau said:
Novice here, but maybe some of you who are more experienced can chime in. Obviously, we
are still fairly far out from the event and much can change, but based on the model handling on the storm yesterday, how do you feel about the chances of a potentially more potent storm next weekend?


Sent from my iPhone using Tapatalk
Click to expand...
If you read griteater's post he lays out how that might come about. He's well respected here for his analysis
 
njbarrineau said:
Novice here, but maybe some of you who are more experienced can chime in. Obviously, we
are still fairly far out from the event and much can change, but based on the model handling on the storm yesterday, how do you feel about the chances of a potentially more potent storm next weekend?


Sent from my iPhone using Tapatalk
Click to expand...
If a storm from the gulf gets too wrapped up the waa is a problem. A weaker storm still delivers the goods, but without the warm nose problems. You don't need tons of moisture to get a good dump over running cold air in place. Many of the best storms are weak ones running by in Fla.
 
njbarrineau said:
I can’t remember that happening at all.


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This wasn't that unusual in the 70's & 80's.
We would get 2 low pressures form in the Gulf and work there way NE days apart.
There was one in the early 80's were we got 2 six inch snows in GVL county 48 hours or less apart from 2 different low pressures.
It has happened just not a lot since 90.
Our elder board members will remember.
 
CaryWx said:
Great analysis grit! Do you think this gets resolved on the models in the next 24-36hrs or so? There seems to be good agreement on the storm signal and has for days just not on the track/intensity fully yet. I know resolving p-types and their locations will likely be another 72hrs or so.
Click to expand...
Thanks for that....yeah, 24-36 hrs to get a better idea sounds about right
 
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