December 8-10, 2018 Winter Storm

[Brick Tamland]

So really this is coming down to the globals vs. the NAM. But even the NAM looked better last run. 

[calculus1]

WPC Probabilities of greater than 4 inches of snowfall 72 hours from now:

[Orangeburgwx]

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
The main concerns are a possibility of a wintry precipitation
mix Saturday through Monday and heavy rain late Saturday through
Sunday morning.

Surface high pressure will extend from the Midwest into the mid-
Atlantic region over the weekend. This ridge will direct a cold
northerly flow into the forecast area. Low pressure along the
western and central Gulf Coast Saturday will move northeast and be
near the Southeast Coast Sunday and Monday. The GFS and ECMWF plus
ensemble guidance are in good agreement showing this general
pattern.

Saturday...Rain is still expected to overspread the region
Saturday. However, there is uncertainty with the timing. There
will be considerable dry air to overcome initially. Compared to
the ECMWF, the GFS has been faster moving the deeper moisture
into the area. We used an average of the guidance with the
chance increasing from southwest to northeast with pops
increasing to categorical in the southwest part during the
afternoon. It will be a cold day because of a wedge pattern and
cloudiness. We followed the lower guidance temperatures. Good
agreement model forecast soundings and surface wet bulb
temperatures indicate all-liquid precipitation through the day
Saturday.

Saturday night...The strongest isentropic lift is forecast to
arrive Saturday night with an easterly 40- to 50-knot h85 jet.
Heavy precipitation may occur. An average of the GFS and ECMWF
indicate rain totals Saturday night of 1 to 1.5 of an inch with
the greater amounts in the south section. Model forecast
soundings indicate liquid precipitation in the central and south
sections, but mixed precipitation in the north. The profiles
support mainly a rain and sleet mix but there may be enough
surface-layer cooling for freezing rain in the north part. The
NAM indicated a much colder near-surface layer. We leaned toward
the ECMWF and GFS because of model consistency and more cold
air is usually in place before what the NAM indicates actually
occurs. The ECMWF depicted the surface wet bulb temperatures
lowering to around 31 in our northern county of Lancaster. The
GFS indicated around 34. We used the ECMWF and included a rain,
freezing rain, and sleet mix in the north part. Based on the
forecast temperatures there should be little freezing rain or
sleet accumulation. However, a verifying forecast soundings just
slightly cooler would lead to much more significant accumulations.

Sunday and Sunday night...Heavy precipitation may continue into
Sunday mainly associated with the h85 jet. Intensity may be
less Sunday afternoon and night and the precipitation may become
drizzle because of mid-level dry slotting. The GFS and ECMWF
indicate rain totals 0.5 to 1 inch Sunday and Sunday night. The
warm nose associated with the h85 jet should be more dominate
Sunday. However, the GFS and ECMWF forecast soundings indicate a
near-freezing cold near-surface layer continuing with a profile
supporting mixed rain and sleet in the north part. Both models
also show near-freezing wet bulb temperatures in the north part
mainly in Lancaster County indicating a freezing rain threat.
Again, based on the forecast temperatures there should be little
freezing rain or sleet accumulation. However, a verifying
forecast sounding just slightly colder would lead to much more
significant accumulations. The rain totals through Sunday
indicate there may be some localized minor flooding. The totals
may eventually lead to river flooding at some of the river
forecast points but frozen precipitation will occur over part of
the headwaters indicating any river flooding will likely be
minor.

Monday through Tuesday...There is increased uncertainty Monday
into Tuesday. Low-level cooling may occur on the backside of the
low as it shifts farther east or northeastward. The models
indicate wrap-around moisture but have not been consistent with
the moisture depth and the development and placement of the
cold upper system. The moisture and instability associated with
the upper system plus wrap-around low-level moisture supports
snow showers. The moisture will probably be shallow and the GFS
and ECMWF liquid equivalent precipitation indicate light amounts.
We have forecasted a chance of snow showers.

Summary...Nearly all GFS and ECMWF ensemble members support
periods of frozen precipitation in the north including Lancaster
County. The threat timing is Saturday night into Tuesday
morning. Confidence is increasing that within a few days a
winter weather advisory or winter storm warning will be needed.

Farther south in the central and south sections that include
Columbia and Augusta there is less confidence of reaching advisory
or warning criteria. The possible frozen precipitation timing for
the central and south part is mainly Monday into Tuesday morning
predominately associated with the cold upper system. Issues cannot
be ruled out sooner in the Columbia area based on the NAM forecast
of much more low-level cooling as early as Sunday.

The rest of the medium-range period...We expect dry high pressure
will dominate Wednesday. A warm front may bring rain Thursday.

&&

 

 

Wow they wrote a book

[Wow]

FV3 trended south and colder

[buckeyefan1]

*******Just a friendly reminder to keep it on topic and make use of the banter threads for your non topic related musings *******  

[LKN WX]

30 minutes ago, Queencitywx said:

Could definitely see this being a situation in CLT where Davidson/Mooresville see double digits, Huntersville gets 5”, an inch or two at carowinds and freezing rain once you get to Dave Lyle Blvd in RH.

The drive up Hwy 16 or 77 from 485 should be an interesting trek this weekend.

[SENC]

@Orangeburgwx, We have a 1 in 10 "chance".. 

[jburns]

2 hours ago, magpiemaniac said:

Or as the rest of us call it, the Triad.  

For your future reference, the Triangle is Raleigh, Durham, Chapel Hill. The Triad is Greensboro, Winston-Salem, High Point.

[jjwxman]

18z FV3, hr 72. 

[Jet Stream Rider]

I want to see where and when the slp becomes established in the gulf as a marker and see what the models say then. That is supposed to happen around 12z Saturday.

Right now the energy coming on shore in socal is so slow, I'm a little concerned it will go up the backside of the suppression.

 

[SENC]

Looks  "somewhat" better for Me & @orangeburgwx , on the backside, We "might" see "something".. 

As it lifts off to the northeast Mon, shortwave energy will dig
down clouds and pcp will wrap around the back end of the system
as it lifts off to the northeast Mon night. This will coincide
with decent cold air advection. Therefore some flurries or snow showers are
not out of the question overnight Mon.

[BullCityWx]

18z GEFS means looking healthier 

[Wow]

1 minute ago, Queencitywx said:

18z GEFS means looking healthier 

Yes.. reversed itself from the 12z output.  Good to see.

[rduwx]

26 minutes ago, Brick Tamland said:

So really this is coming down to the globals vs. the NAM. But even the NAM looked better last run. 

I believe the Nam looking better is a matter of opinion... LOL! I don't think .8 of zr is better. Just give me the rn. Like I said that's a matter of opinion. 

[shaggy]

13 minutes ago, jjwxman said:

18z FV3, hr 72. 

That's a horrible map for me in Pitt county lol. Literally snow over my house and rain just a few miles away. Even verbatim I'm right on the line and I suspect I'm getting my usual 33 and rain. 

[WeathermanTy]

13 minutes ago, Jet Stream Rider said:

I want to see where and when the slp becomes established in the gulf as a marker and see what the models say then. That is supposed to happen around 12z Saturday.

Right now the energy coming on shore in socal is so slow, I'm a little concerned it will go up the backside of the suppression.

 

So do you think it will track further north? 

 

[wake4est]

Dang the fv3 is robust with precip into Monday evening 

[Jet Stream Rider]

5 minutes ago, WeathermanTy said:

So do you think it will track further north? 

 

I think it could. My thinking is that once it is located in the gulf at a specific time, the models can adjust, and its a milestone in the evolution of the system.

Looking at the energy now on the coast of southern California, it just looks so slow. Of course the surface low will form out front of it, and we need that surface low in the gulf or at least along the shoreline. For the forum members that want to see snow, we need it to stay suppressed.

And I want to see if it is early or late to that point, and that will effect things down stream.

[Wow]

This is nearly all snow north of 85... transition zone south of there

[strongwxnc]

This is nearly all snow north of 85... transition zone south of there

Nothing but many consistent for the fv3


.

[WeathermanTy]

3 minutes ago, Wow said:

This is nearly all snow north of 85... transition zone south of there

When do the 18z CMC and Euro come out? 

[Amos83]

2 minutes ago, Wow said:

This is nearly all snow north of 85... transition zone south of there

Needless to say the FV3 is going to make a name for itself with this storm. We will either never take it seriously again or crown in the new king

[Waiting on snow]

4 minutes ago, Wow said:

This is nearly all snow north of 85... transition zone south of there

 

5 minutes ago, Wow said:

This is nearly all snow north of 85... transition zone south of there

Yes looked to me like it would have stayed snow from GSP all the way up. Does anybody have the Kuchera?

[Wow]

4 minutes ago, strongwxnc said:

Nothing but many consistent for the fv3


.

It really has been quite consistent.  Here's a trend loop of the last TWENTY runs of the FV3 total snowfall...

[SnowNiner]

If the euro ticks colder too with the 850s and keeps them in the upstate I'll feel much better. Last run it really warmed once the low got to the coast. Great to see gfs and fv3 correcting colder a bit this evening.

[sarcean]

3 minutes ago, Amos83 said:

Needless to say the FV3 is going to make a name for itself with this storm. We will either never take it seriously again or crown in the new king

Well it takes over for the GFS in less than a month and the formulas could still be tweaked (still in beta) but here is hoping it's accurate 

[HKY1894]

mother of god

[SnowNiner]

Woah!! That's as big as I've seen! please let the other models pick up like that tonight...

[Poimen]

This is almost comical. Close in: 

[Jaguars]

8 minutes ago, Wow said:

It really has been quite consistent.  Here's a trend loop of the last TWENTY runs of the FV3 total snowfall...

All I can say is Wow