Jump to content
  • Forum Image
NorthGeorgiaWX

Thursday, February 20

Recommended Posts

Good morning! This is an "early" morning edition. 🙂 It's 3:04 AM and do you know where your children are? 😜

Here's the current big picture.

Snap346063874.thumb.png.4feb71b56cf727415638f88bcfe6cadf.png

 

I was going to post a bunch of images from the HRRR and NAM but the more I started thinking about it, the more I thought against it. It's a lot or work for less than an inch of snow for the vast majority of people. 

Here's the way I see things happening. I don't think anyone will see anything frozen before 10-11 AM. After that, the NAM and HRRR start to differ on upper air temperatures with the NAM being a little colder. The HRRR doesn't even have 925 mb to surface temps below freezing until late in the evening. The bottom line is that it is just going to be too warm for most people to see much of anything. We just won't have enough cold air at all the necessary levels to produce much snow. As NWS MRX said it "While relatively heavy precipitation rates will dynamically cool the atmosphere and low levels today, there is still a considerable thermal barrier to overcome in the low levels for any accumulating snowfall to occur."

That's my take on it. As always, follow your local forecast office for official information. In this case, I think the "official" NWS forecast is a good one. I believe that late this evening when things finally do drop below freezing for the mountainous areas, black ice will be a problem, but other than that, this is much ado about nothing the way I see it. 

ndfd-conus-atlanta-total_snow_10to1-2243200.thumb.png.f778f59f55e4a36134b5427728c85789.png

 

Right now at 3:34 AM the below freezing air is a LONG way off as you can see by the red line. The wedge is trying to form and the pressure signature is evident in this image. 

Snap346063876.thumb.png.a1b576438aaaa43901c35a9d17006332.png

 

I'll have updates all day, and I will have images showing where the cold air is located so you'll have a heads up before any frozen precipitation starts.

Back in a little while...

ffc-20.png.e642750f73cb80ba8d4e72a667c915bc.png

mrx-20.png.cd26b1678d5a9764adc7c17db92bf75a.png

bmx-20.png.13c02677f461c5a4e4ddd105830f8873.png

  • Like 2
  • Thanks 1

Share this post


Link to post
Share on other sites

GSP 

Quote

Thus, cyclogenesis
is well underway in the vicinity of the western Gulf Coast, and
resultant increase in frontogenesis and QG forcing will allow the
precip shield...currently as far east as central AL and west-ctrl
GA...to continue progressing northeast, likely reaching far western
portions of the forecast area by 12Z. In a perfect world, the cold
air would already be in place, and this would be a bit of a no-
brainer. Alas, this is not the case...as per usual.
As of 08Z,
surface wet bulb temps <= 32 are confined to elevations above about
3000 ft across the ctrl and nrn NC mtns.
However, NE flow responding
to an expansive surface ridge extending eastward from an almost 1050
mb high over the Corn Belt will continue to push cooler and drier
low level air into the forecast area throughout the day. However,
the atmosphere is not exactly going to be in any hurry to push this
cold air south and west...at least not until the low level flow
intensifies in response to pressure falls off the Southeast coast
later today. This sets us up for the classic Carolinas cold air vs.
forcing/moisture race.

 

Quote

Further complicating matters is the NAM's depiction of an
increasingly prominent warm nose between ~4 and 7 kft in the
vicinity of the I-85 corridor and points south.
The model began
depicting this a couple of cycles ago, and it has a rather lengthy
history of accurately picking up on such features before other
models catch on.
If this does indeed occur, it will
a) delay any transition away from rain, as surface temps are unlikely to dip
below the mid-30s along the I-85 corridor, and
b) increase the likelihood of sleet, which would undercut the accum potential
substantially.

 

  • Like 1

Share this post


Link to post
Share on other sites

Murray County is now a part of the Winter Weather Advisory

Quote

Murray-
415 AM EST Thu Feb 20 2020

...WINTER WEATHER ADVISORY IN EFFECT UNTIL 1 AM EST FRIDAY...

* WHAT...Mixture of rain and wet snow possibly transitioning to
  all snow. Total snow accumulations of up to one inch, with
  isolated higher amounts in higher elevations.

* WHERE...Murray County. The most hazardous conditions will be at
  the higher elevations above 2000 feet.

* WHEN...From 5 AM Thursday to 1 AM EST Friday.

* IMPACTS...Plan on slippery road conditions. The hazardous
  conditions could impact the morning or evening commute. Patchy
  black ice following the snow Thursday Night could create
  especially hazardous driving conditions.
 

 

  • Like 1

Share this post


Link to post
Share on other sites
Quote

Fannin-Gilmer-Union-Towns-Pickens-Dawson-Lumpkin-White-
Including the cities of Dahlonega and Cleveland
415 AM EST Thu Feb 20 2020

...WINTER WEATHER ADVISORY REMAINS IN EFFECT UNTIL 1 AM EST
FRIDAY...

* WHAT...Mixture of rain and wet snow transitioning to all snow.
  Total snow accumulations of up to one inch except up to two
  inches in the highest elevations, with isolated higher amounts
  possible.

* WHERE...Northeast and portions of north central Georgia. The
  most hazardous conditions will be at the higher elevations above
  2000 feet.

* WHEN...From 5 AM Thursday to 1 AM EST Friday.

* IMPACTS...Plan on slippery road conditions. The hazardous
  conditions could impact the morning or evening commute. Patchy
  black ice following the snow Thursday Night could create
  especially hazardous driving conditions.
 

 

  • Like 2

Share this post


Link to post
Share on other sites

NWS Atlanta

Quote

While temperatures remain
above freezing areawide at this hour, temperature profiles will
become supportive of wintry precipitation, primarily in the higher
elevations of the north Georgia mountains from midday and into the
afternoon hours
. Profiles continue to support a rain/snow mix
transitioning to light snow in these areas, though a more mixed bag
perhaps including sleet pellets is possible at the onset. The more
significant accumulations are expected to remain limited to higher
elevations where 1-2" snowfall accumulations are forecast through
this evening with locally slightly higher totals possible
.
A Winter
Weather Advisory remains in effect for these locations through 1 AM
Friday where some roads could become slippery. At lower elevations,
brief light snowfall accumulations are possible, especially on
elevated and grassy surfaces, but warmer temperatures should
preclude more significant accumulations.

Precipitation will rapidly dwindle from north to south through the
evening. As colder air continues to quickly filter southward along
the back edge of the precipitation, a brief light/rain snow mix or
light snow shower would be possible as far south as the Atlanta
metro, but no impacts would occur. Overnight temperatures will drop
below freezing across north Georgia after precipitation has ended,
so patchy black ice would remain possible through Friday morning,
primarily on protected/lesser traveled routes.

 

  • Like 1

Share this post


Link to post
Share on other sites

good early morning...I have a meeting in Marietta today live in Bogart.  Do you think I will be impacted later today.  Just hate being on roads with crazy drivers.

  • Like 2

Share this post


Link to post
Share on other sites
Just now, GaDawg said:

good early morning...I have a meeting in Marietta today live in Bogart.  Do you think I will be impacted later today.  Just hate being on roads with crazy drivers.

I don't think that any road will be bad until later this evening except for maybe the higher elevations. Crazy drivers is a given isn't it? 🙂 

  • Like 1

Share this post


Link to post
Share on other sites

Yes I am trying to decide if I ride with someone or drive in case things do get worse than expected and I can leave earlier.

  • Like 1

Share this post


Link to post
Share on other sites
1 minute ago, GaDawg said:

Yes I am trying to decide if I ride with someone or drive in case things do get worse than expected and I can leave earlier.

What time frame are you talking about?

  • Like 1

Share this post


Link to post
Share on other sites

Over here on the side of town where you and I live in, we won't go below freezing until later tonight, and that applies to most of the metro area. You would be back home before things start to freeze. 

  • Like 1

Share this post


Link to post
Share on other sites

The coldest road temp I'm finding this morning is at Neels Gap at about 3300 feet where the road is 40º and the air is 37º. This is out in the middle of nowhere and is a good indicator about what the rest of the mountains are seeing, especially at that elevation. There are not a lot of reporting stations in that area and we generally have to rely on people on the ground for information.

Snap346063884.png.a68da10ca6aaf732184a8edc20088e02.png

Snap346063886.thumb.png.b6d3e188f406c7b138934b756db7d6af.png

  • Like 2

Share this post


Link to post
Share on other sites

35.8 with a dewpoint of 29 with a light rain/sleet mix in Sky Valley. NWS has cut down totals to 1-3” and mentioned a lot more sleet today. 

  • Like 2

Share this post


Link to post
Share on other sites

At this point, we watch and wait. I don't expect to see any frozen precip in Georgia until at least 10-11 am, and that would be sleet if anything, the upper level temps just wouldn't support snow at that point in time. 

This is the temp and 10m winds

Snap346063887.thumb.png.3c32bcb0d0e22618d752cc86245dd526.png

 

This is the dewpoint and 10m winds

Snap346063888.thumb.png.a78679250b87f673dc63b2062e872d5d.png

 

 

And this is the P-Type radar

Snap346063889.thumb.png.1b7a87890989574697c558eb7ba85cbc.png

  • Like 1

Share this post


Link to post
Share on other sites
8 minutes ago, Preston said:

35.8 with a dewpoint of 29 with a light rain/sleet mix in Sky Valley. NWS has cut down totals to 1-3” and mentioned a lot more sleet today. 

Nice to have your temp/dewpoint, there aren't many stations to get data from in your area.

  • Like 1

Share this post


Link to post
Share on other sites

The first image is the forecast around 10-11 AM and shows the future low pressure that is now starting to form in the western Gulf. The wedge continues to build in from the NESnap346063892.thumb.png.d66beb7d33a357a07badf88348486d19.png

 

This image is in about 6 hours. Notice that the surface low tightened up (red arrow) but the pressure remained the same while the wedge (blue arrow) continues to try to build SW. At this point, a new low (magenta arrow) is forming off the coast of Georgia, and that will eventually become the main low. 

Snap346063893.thumb.png.84102e138f460f32d02f1beae4f55eb9.png

  • Like 1

Share this post


Link to post
Share on other sites

When I left home in Bogart it was 43/88%.  It is raining here at work in Lithonia and temp was the same not sure about humidity.

  • Like 2

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.




×
×
  • Create New...