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Potential Winter Threat - December 6-11

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This forecast is truly HARD I mean my area could have nothing but a cold rain or a crippling ice storm with some snow thrown on top and anything in between the two!!  WOW you gotta love the weather and I DO!!

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Extremely difficult forecast. It's easy to forecast rain, you either get it or you don't. But winter weather takes things to a whole different level. 

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OK, the Greenville/Spartanburg AFD... this is LONG

Quote

.NEAR TERM /THROUGH SATURDAY/...
As of 230 pm: We will be upgrading the Winter Storm Watches to
Winter Storm Warnings, and moving the start time up to noon on
Saturday for all of the southwest mountain counties.

For the synoptic setup, water vapor imagery reveals a mid/upper
level southern stream circulation over southern California and
Arizona late this afternoon, with a deep plume of moisture streaming
around this system, across Texas, and into the southeastern U.S. on
downstream zonal flow. Meanwhile, sprawling 1035 mb surface high
pressure stretching from the midwest to the Virginias late this
afternoon and the nose of this high will spill southward east of the
Appalachians tonight. As the southern stream wave moves east through
the period, an associated surface reflection will develop along the
TX/LA Gulf Coast overnight and then progress east to the FL
panhandle by late Saturday. Although weak upglide may develop atop
our region over the developing wedge-frontal boundary, the
isentropic lift is expected to gradually improve through the period
as the main waves move east. Deeper moisture will also return
through Saturday as profiles steadily saturate. Deeper layer Q-
vector convergence with the upper forcing will also arrive later
Saturday afternoon to improve precipitation rates. So, the trend
should be generally light QPF in the pre-dawn hours across southwest
sections tonight, picking up from the southwest Saturday morning,
with the best QPF of the period during the afternoon and early
evening hours.

Precipitation types will be critical and the models feature a lot of
near-zero isotherm profiles as the soundings wet bulb down. For now,
a top down approach keeps most of the early day precip as rain east
of the mountains, but would not at all be surprised by sleet and
snow mixing in at times. With snow profiles preferred in the
mountains, with steady accumulating snow developing a bit earlier,
the southern mountain Winter Storm Warning now begins at noon. The
bulk of the wintry precipitation will occur in the short term
period, so see that discussion below. Temperatures will certainly
lock in across the region by mid-afternoon with full blown,
classical, cold air damming getting underway.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/...
As of 220 PM Friday: Confidence remains high on winter storm
reaching peak intensity late Saturday night and Sunday morning,
with the 12z guidance cycle having changed little in terms of the
general setup for CAD interacting with coastal low pressure. At
the start of the period Saturday evening, low-level warm advection
will be starting to set up, but not yet having warmed temps in
the midlevels. Therefore a relatively straightforward rain-snow
split is expected initially, based on sfc temp. Nonetheless, used
the Top-Down technique to produce the p-type trends throughout the
period. Profiles aloft are already expected to be nearly isothermal,
and near 0C, over a fairly deep layer.  Slight warming occurs
overnight which will introduce enough of a warm nose to permit
sleet to mix in by daybreak, if not sooner, across the periphery
of the colder air. The deepest forcing and moisture is expected to
occur early Sunday, with precip rates peaking to match. For most
of western NC this still looks to translate into heavy snow. Even
using relatively low SLRs to account for the isothermal profiles,
rates meeting or exceeding 2 inches in 3 hours are expected
throughout the morning.

Sfc temps remain very important as the warm nose continues to
strengthen. The raw models, which normally are the best choice
during a wedge, mostly depict temperatures staying above freezing
in the areas where the warm nose strengthens enough to support a
change from snow to sleet or FZRA. So while temps were initially
populated with raw values, they were adjusted down closer to
wet-bulb temps. While the NAM has trended somewhat warmer at the
surface, its warm nose is not nearly as strong as it previously
progged. This puts it in line with the GFS/EC/Canadian at the sites
where we were able to sample vertical profiles. The consensus still
does support the warming later in the day, so the pure-snow area
shrinks to the northern NC mtns/Piedmont as we progress through
Sunday. Some areas of GA and the Upstate are even expected to
warm slightly above freezing, which should result in precip
changing over to rain again. The warming is expected to continue
into Sunday evening as the sfc low pushes offshore and the wedge
weakens a tad--while the pressure pattern reflects less wedging we
will still have some weak WAA in place. As previously advertised,
precip chances diminish only to the chance range, as a upper-level
deformation zone begins to cross the area. The models continue to
depict spotty (but appreciable) QPF lasting through Monday, and
the GFS/EC both now depict yet another cutoff 500mb low swinging
into the Southeast on the heels of the first wave. PoPs decline
gradually Monday night but this may eventually prove too fast in
light of the trends with that next wave.

Heavy snow and/or sleet accumulation is still forecast in our
western North Carolina zones north of the Black Mountains and east
of the Blue Ridge Escarpment, plus the adjacent SC zones--i.e.,
the areas that were already in a Winter Storm Watch. Therefore
all of these zones will be upgraded to a Winter Storm Warning
effective 00z Sunday. We dicussed the possibility of hoisting a
Winter Weather Advisory for the rest of the CWFA, given sleet/ice
accums that end up below warning criteria, but certainly enough to
have impact. However, with the temps aloft and at the sfc being
especially critical, even a slight increase in QPF or warming of
profiles could result in some of these areas reaching warning
criteria on tonight`s forecast package. Thus we will give the
next shift the option of upgrading these areas to warning instead
of advisory.

Even after the current warning expires at noon Monday, an eventual
Winter Weather Advisory likely will be needed for some or all
of the area on account of poor road conditions likely lingering
into Tuesday.

 

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I think I know your answer to this, but I'm going to ask anyway. I'm hosting a house concert in south Dahlonega (not in the mountains) with 60 attendees coming from all over tomorrow night from 6pm to 9:30pm and I'm getting a LOT of calls about the weather (like I know the answer).  Is there ANY way to tell what time-ish treacherous weather moves into my area?  We need to make a decision about cancelling or moving ahead and any guidance you can give me would be greatly appreciated!

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16 minutes ago, Hrtnsoul333 said:

I think I know your answer to this, but I'm going to ask anyway. I'm hosting a house concert in south Dahlonega (not in the mountains) with 60 attendees coming from all over tomorrow night from 6pm to 9:30pm and I'm getting a LOT of calls about the weather (like I know the answer).  Is there ANY way to tell what time-ish treacherous weather moves into my area?  We need to make a decision about cancelling or moving ahead and any guidance you can give me would be greatly appreciated!

According to the NWS, you should be good.

Snap34566.thumb.jpg.3b89d213611f4ded37bd70ea3e531e5b.jpg

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5 minutes ago, matt40 said:

Steve!  You use a mouse with your left hand?  Weirdo.  😉😜

I can actually use BOTH hands. Skilz. 😜

I throw a ball right handed, bat right handed, my right hand is favored hand in shooting a basketball, could play tennis and racquetball with both hands, bowl right handed, write left handed and mostly use a mouse left handed. LOTS of SKILZ! LOL! Of course, I can't write anymore, looks like chicken scratch. 🙂

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1 minute ago, NorthGeorgiaWX said:

I can actually use BOTH hands. Skilz. 😜

I throw a ball right handed, bat right handed, my right hand is favored hand in shooting a basketball, could play tennis and racquetball with both hands, bowl right handed, write left handed and mostly use a mouse left handed. LOTS of SKILZ! LOL!

What?  That is skilz.  Impressed.

Not to toot my own horn, but I am cross eyed dominant.  Boom!  Left eyed dominant, but do everything right sided, but for shooting rifles, got to aim and all.  :classic_rolleyes:

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OK folks, this is VERY important. This is the latest NWS Atlanta Winter Weather Briefing. I've saved it as a video, each PowerPpoint slide last 10 seconds before it moves on to the next slide. You can pause the video player to read. Let's see if this works... 😉

 

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1 minute ago, rwarren5 said:

http://www.resortcams.com/webcams/brasstown-bald-mtn-north/ 

Cloudy and overcast at Brasstown Bald summit. Lots of good web cams on this site to watch the incoming storm, even if it misses us. 

Yep, have them both on my site:

http://www.daculaweather.com/4_brasstown_bald_north.php

http://www.daculaweather.com/4_brasstown_bald_south.php 

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Quote

Cocke Smoky Mountains-Southeast Greene-Blount Smoky Mountains-
Sevier Smoky Mountains-
Including the cities of Cosby, Cedar Creek, Cades Cove,
and Gatlinburg
352 PM EST Fri Dec 7 2018

...WINTER STORM WARNING IN EFFECT FROM NOON SATURDAY TO NOON EST
MONDAY...

* WHAT...Heavy mixed precipitation expected. Total snow
  accumulations of up to 14 inches and ice accumulations of
  around one quarter of an inch expected.

* WHERE...Cocke Smoky Mountains, Southeast Greene, Blount Smoky
  Mountains and Sevier Smoky Mountains Counties.

* WHEN...From noon Saturday to noon EST Monday.

* ADDITIONAL DETAILS...Power outages and tree damage are likely
  due to the ice. Travel could be nearly impossible. The
  hazardous conditions could impact the morning commute.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Winter Storm Warning means significant amounts of snow, sleet
and ice will make travel very hazardous or impossible.
 

 

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2 minutes ago, Carol said:

It’s going to be interesting!!

You bet! 🙂 This whole winter is going to be interesting! Good thing I have the time! 🙂

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Looks like they've taken down the special weather advisory for Fannin. Do they do this when they are issuing a new advisory or watch?

EDIT** NVM, it's back.

Edited by SlicNic13

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Crazy gradient in Rabun county on the latest GFS, from less than an inch to over a foot. But based on soundings areas with lighter snow totals would have a lot more sleet when the rates are heavy.

gfs_2018-12-07-18Z_096_35.621_275.206_34.145_278.027_Snowfall_72_highways_cities.png

 

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