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Wintry Jan 15-16 Winter Storm Discussion & Obs

Heres the Gefs: fixed 6z

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sfcwind_mslp.conus.png

sfcwind_mslp.conus.png
 
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Chazwin said:
Yes that is the trend on the GEFS because you’re seeing less and less in the way of off shore tracks… I don’t believe the track will be off shore… I think the track the Euro shows makes much more sense and it’s supported by both EPS and the GEFS
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There are much less tracks offshore, but in four runs Kentucky has went from zero members to four or five, with a lot more members now tracking through central GA and central NC. There is a massive NW trend of the low tracks on the individual members. Now it may start trending the other way but the GEFS has went from a scrape to major bleeding and the wounds keep getting worse.
 
Arcc said:
There are much less tracks offshore, but in four runs Kentucky has went from zero members to four or five, with a lot more members now tracking through central GA and central NC. There is a massive NW trend of the low tracks on the individual members. Now it may start trending the other way but the GEFS has went from a scrape to major bleeding and the wounds keep getting worse.
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Agreed, but ultimately what most mets look at and what I believe GSP is doing based on their discussion is focused on where the members are clustering and how that supports other models… right now that’s between I-95 and the coastline, and has been fairly consistently clustered there
 
Chazwin said:
Agreed, but ultimately what most mets look at and what I believe GSP is doing based on their discussion is focused on where the members are clustering and how that supports other models… right now that’s between I-95 and the coastline, and has been fairly consistently clustered there
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Gsp is discounting the gfs op atm
 
LONG TERM /SATURDAY THROUGH TUESDAY/...
As of 320 am EST Wednesday: The latest guidance suite is starting to
feature a bit better agreement on the overall aspects of the winter
storm likely to impact the area over the weekend. However, there
remains some variation regarding low tracks, thermal profiles, and
QPF for various periods, and these details continue to make
precipitation types and amounts highly uncertain.

Nearly all solutions have trended toward cutting off the southern
portion of the split upper flow near the lower Mississippi River
Valley by late Saturday. In a slight role reversal over the past 24
hours, the ECMWF 500 mb prognostic now features a cutoff low with a
farther south low center position than the operational GFS. However,
both models agree fairly well on the general timing, migrating the
system over the Deep/Mid South Sunday and then over the Carolinas
Sunday night as the system phases back into the northern stream.
Meanwhile, sprawling surface high pressure from southern Ontario to
New England will establish a strong cold air damming configuration
east of the Appalachians ahead of the storm on Saturday. The
resulting surface-based cold layer is becoming one of the more
confident aspects of the upcoming weekend storm. The onset timing of
wintry precipitation, however, remains uncertain. There are hints of
weak and shallow upglide developing over the preexisting baroclinic
zone as early as late Friday night or Saturday morning, with the
isentropic lift slowly improving the day on Saturday well east of
the approaching system. The forecast features below guidance
temperatures and wintry ptypes at onset across the northern half.

The period of deepest moisture and best forcing now looks slated for
Saturday night through Sunday as a Deep South surface wave
transitions to the Carolina coast. Strong jet-level divergence is
indicated during this period and deformation zone forcing will
likely impact our area by Sunday, especially over western NC given
the current low track forecast. Precipitation types remain
challenging. Profiles have trended to stronger warm nosing across
the southern half of the area, with prolonged sleet and southern
tier freezing rain now quite possible. However, the operational
model runs appear warmer than most of the ensemble members, so much
of the QPF could still fall as snow. An ensemble approach has been
adopted for weekend profiles, which leads to more snow in the
forecast than might be indicated on operational model profiles. The
mixed ptype belt should especially impact locations southeast of I-
85, but with a changeover back to snow likely occurring from the
west throughout on Sunday night as the system pulls away to the
northeast. Scattered upslope snow showers should persist along the
TN border counties through Sunday night, and possibly well into
Monday, further enhancing snow amounts there. We are still a
bit out of the Winter Storm Watch timeframe, so this will remain
highlighted in the HWO. The main change will be the addition of
sleet and freezing rain to the forecast, especially across the
southeast part of the area.

Another vigorous shortwave is forecast to drop southeast into the
eastern trough Monday before the flow pattern flattens out by
Tuesday. This could briefly reinvigorate western mountain snow
showers, which may not have completely ended from the weekend system
before this wave arrives. Upslope moisture will gradually end Monday
night into Tuesday.
 
The GFS Did well moving this to a Miller B which the GEFS is figuring out but the evolution of the two are nothing alike. GEFS actually shows how a LP would track through central Alabama before a transfer occurs to the coast which is believable due to the strength and f the Cold dome. The GFS basically cuts through the Ohio valley and transfers to the 95 corridor and still plows the low through the CAD. That isn’t happening. Idc how much y’all want to push that theory but the GFS does this with any storm that has any type of CAD.
 
I noticed the NAM at 84 was close to the GFS in its location. Will be interesting to see where she goes when we get in range. With our hp retreating the gfs solution is entirely possible.
 
Regardless, the way this thing looks right now, somewhere in the CAD areas of Upstate, Ne Ga, NC is gonna see a 12" wallop!

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Just IMO, I feel like this year there’s been a lot of times where the models have amplified the storm too much around this range before the NAM comes out. Then it trends the other direction once the storm starts being sampled.


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iGRXY said:
The GFS Did well moving this to a Miller B which the GEFS is figuring out but the evolution of the two are nothing alike. GEFS actually shows how a LP would track through central Alabama before a transfer occurs to the coast which is believable due to the strength and f the Cold dome. The GFS basically cuts through the Ohio valley and transfers to the 95 corridor and still plows the low through the CAD. That isn’t happening. Idc how much y’all want to push that theory but the GFS does this with any storm that has any type of CAD.
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Thankfully at this point GSP agrees on the ensemble approach for now. Sucks bad this has morphed to a Miller B, however somehow keeping this 100% to our south seemed very odd to begin with based on how far east it was coming down the pipe. Hopefully it can transfer low and south and operationals will tick south/east. But that may be a losing battle. Long term, I think we're going to need to some west based blocking or a STJ wave to realistically keep our storms south of us in this pattern. Lesson learned.

GSP Discussion:
The period of deepest moisture and best forcing now looks slated for
Saturday night through Sunday as a Deep South surface wave
transitions to the Carolina coast. Strong jet-level divergence is
indicated during this period and deformation zone forcing will
likely impact our area by Sunday, especially over western NC given
the current low track forecast. Precipitation types remain
challenging. Profiles have trended to stronger warm nosing across
the southern half of the area, with prolonged sleet and southern
tier freezing rain now quite possible. However, the operational
model runs appear warmer than most of the ensemble members, so much
of the QPF could still fall as snow. An ensemble approach has been
adopted for weekend profiles, which leads to more snow in the
forecast than might be indicated on operational model profiles. The
mixed ptype belt should especially impact locations southeast of I-
85, but with a changeover back to snow likely occurring from the
west throughout on Sunday night as the system pulls away to the
northeast. Scattered upslope snow showers should persist along the
TN border counties through Sunday night, and possibly well into
Monday, further enhancing snow amounts there. We are still a
bit out of the Winter Storm Watch timeframe, so this will remain
highlighted in the HWO. The main change will be the addition of
sleet and freezing rain to the forecast, especially across the
southeast part of the area
 
Now with me saying all this, upstate and pretty much everyone south of 40, you need to prepare yourselves that a switch to sleet and freezing rain is likely at some point but the front end thump of snow to me looks likely as of right now. It just depends on how long you can hold off the change and how far north that 850mb LP tracks north.
 
Snownut said:
Regardless, the way this thing looks right now, somewhere in the CAD areas of Upstate, Ne Ga, NC is gonna see a 12" wallop!

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Sleet will probably cut those high total were seeing down imo it will be almost go time before we can pinpoint accumulations.
 
iGRXY said:
Now with me saying all this, upstate and pretty much everyone south of 40, you need to prepare yourselves that a switch to sleet and freezing rain is likely at some point but the front end thump of snow to me looks likely as of right now. It just depends on how long you can hold off the change and how far north that 850mb LP tracks north.
Click to expand...

Personally, I think the front end snow will be rather difficult at first. There will be a lot of virga


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Not sure how this all shakes out. You never really know how the trends will go. We all talk about the Northwest trend but I don’t think there’s actually any real data that says that that happens every time and that that modeled trend is irreversible.

Pretty soon it will be time to look at the mesoscale models where I think will get a better picture of what is about to unfold.


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Jimmy Hypocracy said:
The extent of the warm nose will be sniffed out as soon as the NAM gets in range. Warm nose usually overperforms. The fact that we’re already seeing this much modeled ice is concerning. Wedge always undermodeled as well.
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Except when it doesn’t. PDII, SuperCad 2010 and 2011, etc.
 
Can see the importance of that 50/50....UK is a little weaker with the ull than the Euro but has the 50/50 in a better spot and high pressure is stronger. I think the GFS is on crack but I'm mostly wishcasting...these 50/50's seem to want to lift out quicker so Euro is probably right.

UK v/s Euro

UKEuro.gif
 
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