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NorthGeorgiaWX

Potential Winter Threat - December 6-11

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Man if we were to have 3” of snow and 3/10 of ZR combined with 30-40 mph wind gusts it will be really dicey here in Dahlonega.  Steve how do you feel about this system compared to yesterday at this time??  I’m guessing a lil different??  I do 😂

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6 hours ago, Jay said:

Conceptually, I can see the CAD stretching out through WNW GA. It's happened in the past and, as depicted, pretty much follows the regional geography.

What I am having difficulty with is the cold rain that runs from NE AL into TN and is bounded north and south by freezing rain. I want to say when those of us in NW GA get kissed by the CAD we're typically on the southern end of things and NE AL and S TN are getting frozen or freezing stuff as well. Maybe it speaks to how marginal things are?

Don't think you'll see much up that direction. This CAD isn't as strong as many and it has factors working against it. 

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6 minutes ago, Dahlonegawinter said:

Man if we were to have 3” of snow and 3/10 of ZR combined with 30-40 mph wind gusts it will be really dicey here in Dahlonega.  Steve how do you feel about this system compared to yesterday at this time??  I’m guessing a lil different??  I do 😂

I'm still not convinced that the cold will make it to Gwinnett. We'll see. It may for a few hours at least. I hope I'm pleasantly surprised!

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My brother lives in Sugar Hill down there pretty close to your area!  I think you do see a 6 hour or more period of IP AND OR ZR!  I am not on your level of expertise however.  Do you feel pretty confident in the Dahlonega area getting appreciable winter weather?  Just looked at FFC and the grids updated showing about an inch of snow and about 1/4 of ice for my area 

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The latest (4:58 am) AFD from the Atlanta NWS office

Quote

.SHORT TERM /Today through Sunday/...
Many forecast challenges next 36 hours but primary concerns are
heavy rain and flooding potential this afternoon through
Sunday as well as winter weather p-types and accumulation(s)
tonight and Sunday.

Strong, open short wave currently located over SW TX this morning
still expected to move east across the southern states today and
tonight. With strong NW flow aloft over New England during this
time, strong cold air damming (CAD) event expected to commence
bringing very cool and somewhat drier low level air from the
northeast, which acts to increase warm/moist advection and
vertical motion. Model and guidance QPF quite impressive with
event total amounts 2.5-3.5 inches overall but the far southeast
counties. Have maintained flood watch over the entire forecast
area due to high soil moisture, streamflow and runoff potential
over middle GA from recent heavy rainfall event just last Sun/Mon.
Highest rainfall rates should occur from noon today through 6am
Sunday, though minor flooding will continue through Sun and Mon.

With the cool sfc temps from the CAD and near isothermal profile
aloft hovering near freezing through 600mb, initial round of
heavy precip may fall as sleet or snow mainly over higher
elevations of northeast GA this afternoon and evening. As warm
conveyer belt increases tonight, warm nose aloft warms to +2-4C
while sfc temps drop to or just below freezing. While GFS and EC
guidance, which handle CAD events poorly compared with hires CAMs,
have carefully chosen sfc temp and dewpoint guidance weighted
toward CAMs and MDL National Blend of Models. which has high
weight of CAMs in first 24 hours of forecast. Statistical and
bias- corrected forecasts are much too warm and handle rare, fast-
changing events poorly and were not used. Based on these sfc
temps, p-types and snow/ice accumulations were derived from top-
down methodology and local studies, which were then compared
against and nudged by WPC Winter Weather Desk guidance for a
sanity check and better inter-WFO consistency. Results of these
forecasts used to drive winter storm warning and advisory timing
and areas.

Feel greatest winter impact will be ice accumulation after
midnight tonight through mid-morning Sunday. This could occur in
both the higher elevations and in the areas affected by the CAD
over northeast GA. With such impressive vertical motion and high
QPF, if sfc temperatures go below forecast values (which is as
mentioned above, already weighted toward cooler CAM guidance),
both ice and snow accumulations could go significantly higher
than forecast. Likewise, if temps go a couple degrees warmer than
forecast, will mainly see a heavy rain event with limited winter
weather impacts. If there is one bright spot, its that many businesses
and most schools will be off during this event.

As the first wave moves out Sunday, another weak wave moves in
behind it so have kept clouds and some precip in, though sfc
temps should warm above freezing Sunday afternoon in the wake of
the first wave, so threat for accumulating precip ends Sunday
afternoon.

Will also have some windy conditions this afternoon and tonight as
pressure gradient between strong sfc low over south GA and CAD
wedge. This strong sfc low and winds are a little atypical for
winter CAD events here, so a little more concerned about the
overall strength of this system.

 

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It's going to be a "moment to moment" real-time event. Things will be constantly changing in many locations at once and it will be difficult to keep track of. So to help keep things organized, I've created another forum post for all of the winter weather observations. I would like for people to use that to share any information as it pertains to what's falling in your area. This will be shared with the NWS so make sure you include location (as specific as possible) as well as time. Images may be added here as well.

 

For pictures,  you can post those pictures in this gallery. Be sure to add any details like time and location, that is very important, as we will be sharing those images with the National Weather Service as well.

 

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9 minutes ago, NorthGeorgiaWX said:

My dew point is up and my wet bulb is 37.3, my temp is 37.9. So I'm about as cold as I'm going to get for now.

That’s until the CAD and wedge start to do their magic 

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6 minutes ago, NorthGeorgiaWX said:

These will be updated automatically also

StormTotalIceFcst.png

StormTotalSnowWeb.png

 

 

Talk about walking a fine line here in Gwinnett. 

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As this storm progresses, there are a lot of webcams that will have some great images of the snowfall. Most of these are in NC and I thought I'd share a partial list of some that I watch:

There are many more!

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12 minutes ago, rwarren5 said:

Looks like GSP is being more conservative with their ice accumulation than Peachtree City. 

Expecting more sleet and snow and less freezing rain.

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1 minute ago, Christine said:

I’m going to stay with my mom in Flowery Branch tonight! Hopefully I’ll see something there 🙂

Much better chance there than midtown

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Is this system going to continue to change for the better (snow) in the N. Metro counties? I need a day off on Monday!

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42 minutes ago, NorthGeorgiaWX said:

Expecting more sleet and snow and less freezing rain.

Ugh. Well, as long as I can get to work and back today, I won't complain. Got no plans for tomorrow that involve leaving the house.

:classic_tongue:

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8 minutes ago, John said:

Is this system going to continue to change for the better (snow) in the N. Metro counties? I need a day off on Monday!

Temps will rise above freezing later in the day on Sunday.

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