Jump to content
  • Forum Image
NorthGeorgiaWX

Thursday, November 7

Recommended Posts

Good morning! 

Showers will be the weather word today in advance of our first cold front. Here's a look at the big map.

Snap346062965.thumb.png.90c95c9ded1363c097f42cfaf2a39181.png

 

But you're not wondering about showers are you? ❄️❄️❄️🌡️🍺

Quote

The main concern then becomes a strong cold front forecast to
move across the area in the Monday night and Tuesday timeframe.

An axis of deep moisture will be associated along with an upper
level trough. The GFS and European are in better agreement with
the axis of moisture. The model blends will need to catch up with
the actual rain chances but rain chances will increase significantly
Monday night into Tuesday and diminish/end later Tuesday and Tuesday
evening.

Another concern is the cold air behind the front the will give
potential for a rain/snow mix and possibly changing to all snow
before ending across the far northern counties late Monday night
into Tuesday. As is often the case much of the time, it will be a
matter of the cold air arriving while there is still the potential
for precipitation.

This forecast will continue to evolve and all interested parties are
advised to keep up with the latest forecast for their area over the
coming days.

 

Even this morning's HWO has mention of the possibility.

Quote

400 AM EST Thu Nov 7 2019

This Hazardous Weather Outlook is for portions of North and
Central Georgia.

.DAY ONE...Today and Tonight...

No hazardous weather is expected at this time.


.DAYS TWO THROUGH SEVEN...Friday and Wednesday...

There is a chance of a rain snow mix possibly changing to all snow
over the far north late Monday night and Tuesday.

Otherwise, No hazardous weather is expected at this time.
 

 

As I said yesterday, cold chasing moisture doesn't always work out well as the timing has to be pretty close to perfect, so we'll see how this goes.

Yesterday I showed the GEFS, Euro, and CMC ensembles for Blairsville, and I will continue to use Blairsville as the example so we can watch the trends. Remember, while the snow maps are pretty, the ensembles give you a better idea of the potential of the system, at least until you get within 3-4 days. Even then you always want the full support of the ensemble suite for confidence.

Let me try to explain these images so you better understand what you are looking at. Each ensemble is made up of individual members and those are the rows p01-p50 depending on the model, the Euro has the most. Each row is a model run that has slightly and randomly perturbed initialization parameters so that each run starts off just a little different from the other runs. That is also why each "row" may end up different than any other row. 

At the bottom of each image you see a blue line. That is the control run. Each individual ensemble member initialization is based off of that run, ie, that is the run that the slightly tweaked members are based on. The green bars are accumulated totals. Using the Euro as an example, notice how you see three "step ups" in those bars. That would tend to indicate three different periods of accumulating snow. Notice also the each member may start and stop the horizontal bars at different times and that can be something like timing differences or it may even see a different type of system and therefore showing a different result. 

gfs-ensemble-all-KDZJ-indiv_snow-3084800.thumb.png.2a9debb18553aba6367a53790e2e66a7.png

ecmwf-ensemble-KDZJ-indiv_snow-3084800.thumb.png.a2e63b581fa795d039fdecc74a165ca0.png

cmc-ensemble-all-KDZJ-indiv_snow-3084800.thumb.png.704dc7816f88e41f8237606634a6ecf3.png

 

All the ensembles have trended toward more snow since yesterday, and the Canadian (or course it would be the Canadian) is still going bonkers for snow. Yesterday it was only 6", today the average of it's ensemble members is 8-9". That being said, this can all go the other way, so that is why we have to keep watching these and how they trend. These run 4 times a day, so we have about 20 model runs between now and the event. And please remember, models do not make forecast. The models are simply guidance, a tool for meteorologist to use to "guide" them in the creation of a forecast. Every model has known biases that can steer a particular model output in a certain direction. Meteorologists understand those and can use that knowledge to help determine which model is showing the best solution for a given situation.  If you read the Extended forecast discussion that I post every morning, you'll get a better idea how they do that.

 

Here's a look at the GFS operational run temperatures. The GFS is colder that the Euro right now, so it will be interesting to see how the two models converge on the final solution. Either way, Wednesday/Thursday will be cold.

gfs-operational-KDZJ-daily_tmin_tmax-3084800.thumb.png.65309d99dcda3ff0c097cf1dd2f8e101.png

Here's another unique view of the cold air that is coming. This is a cross section of the atmospheric temperatures over Blairsville with the date going left to right at the bottom. Notice the zero degree (C, or 32F) area next Tuesday/Wednesday. That is when the snow would fall if it snows. That column of air needs to be below freezing so you don't end up with sleet/freezing rain, or even rain. Notice those periods on the chart where it's very warm aloft.

gfs-operational-KDZJ-cross_section_full-3084800.thumb.png.34002da0a8d4bedd6dfcecc89db6f7bc.png

 

So exciting times ahead and we're just getting started! Can't wait to see what winter will bring us! 🙂

Have a great Thursday!

forecast-07.png.5a1a0a80c376e3c769740220984ef14d.png

ecmwf-operational-KDZJ-cross_section_zoom-3084800.png

  • Like 2
  • Thanks 2

Share this post


Link to post
Share on other sites

Just to be clear you said  8-9" possible on Tuesday next week for Blairsville? what about Cherokee county?

  • Haha 1

Share this post


Link to post
Share on other sites

Oh jeez will be on the road to Nashville Tuesday.. hmmm 

  • Like 1

Share this post


Link to post
Share on other sites
36 minutes ago, Jeff9702 said:

Just to be clear you said  8-9" possible on Tuesday next week for Blairsville? what about Cherokee county?

Just to be clear. No. 🙂

  • Like 1

Share this post


Link to post
Share on other sites

6z GFS is really interesting. It's much slower and stronger with the southern piece of energy. Ideally this is what we'd need as it would allow more time for the high pressure/cold to build in out front. However on that run the high moves out just too fast leading to rain. As I've been saying, that is just an absolute classic low track for a southeast winter storm, timing out the cold is always the hard part. The odds of this working out are pretty slim, but the fact that all the necessary players are on the field this early in November is encouraging. 

  • Like 2

Share this post


Link to post
Share on other sites

It's time to share the infamous Brazilian model! This is only for fun because there is no model that can predict snow this far in advance. Green is snow in the top graph. It does show a Dec warmup but big time cold starting the middle of Jan.  🙂 Definitely for entertainment purposes only 🙂

08422W3430N.thumb.png.db83d539a4ed3cd8d49ab833bbb3c3dc.png

 

  • Like 1
  • Haha 1

Share this post


Link to post
Share on other sites

I'm a little confused on the upcoming events. We're looking at a cold chasing rain event possibly in North GA Monday night into Tuesday, and then potentially watching a low tracking low possibly bring a "storm" late next week? Have I got this correct on what we're watching? Two separate events? 

Share this post


Link to post
Share on other sites
13 minutes ago, Nic said:

I'm a little confused on the upcoming events. We're looking at a cold chasing rain event possibly in North GA Monday night into Tuesday, and then potentially watching a low tracking low possibly bring a "storm" late next week? Have I got this correct on what we're watching? Two separate events? 

Well initially the models had been phasing the cutoff low over the SW US into the frontal passage making it all one system on Tuesday, and yes the cold chasing moisture variety. However the last 2 runs of the GFS have left that cutoff low behind in the gulf, creating a potential 2nd system. First things first we'll have to see if the GFS gets any support in this scenario. 

Share this post


Link to post
Share on other sites

Ahh thank you for the clarification. That explains as to why I was scratching my head lol. 

 

Hoping for snow but my wife is not! lol

Share this post


Link to post
Share on other sites

Models are struggling
----------------------------------

Preference: 07/00Z ECMWF and EC Ensemble Mean and 07/12Z NAM
Confidence: Slightly Below Average

The 12Z suite of NCEP guidance continues to struggle with numerous
and hard-to-time shortwave troughs riding around the periphery of
an anomalously strong mid/upper level ridge over the Eastern North
Pacific Ocean
.  The 07/12Z GFS has more energy, and therefore a
stronger frontal progression, into the U.S. Pacific Northwest
while the 07/12Z NAM clustered better with the ECMWF.  Even though
the CMC/UKMET were more aggressive than the ECMWF with the
pattern, those models remainder closer to the NAM/ECMWF idea than
they did with the GFS.

  • Like 1

Share this post


Link to post
Share on other sites
1 hour ago, NorthGeorgiaWX said:

It's time to share the infamous Brazilian model! This is only for fun because there is no model that can predict snow this far in advance. Green is snow in the top graph. It does show a Dec warmup but big time cold starting the middle of Jan.  🙂 Definitely for entertainment purposes only 🙂

08422W3430N.thumb.png.db83d539a4ed3cd8d49ab833bbb3c3dc.png

 

I know this is for entertainment only but how warm would December get?

Share this post


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

My forecast here near Lawrenceville. Does the cold arrive in time or not?

Snap346062977.png.adaca1d5e45d9ea49993f425ed7d80d9.png

If it's anything like the last powerful cold front we had where the temps dropped 15 degrees in like 30 minutes, I say yes. That was a VERY fast transition, just wrong timing. Seems like this front will also be robust. Really hoping this neutral El Nino/La Nina pattern year will bring us the winter we got robbed of last year. 

  • Like 1

Share this post


Link to post
Share on other sites
3 minutes ago, Nic said:

If it's anything like the last powerful cold front we had where the temps dropped 15 degrees in like 30 minutes, I say yes. That was a VERY fast transition, just wrong timing. Seems like this front will also be robust. Really hoping this neutral El Nino/La Nina pattern year will bring us the winter we got robbed of last year. 

Some of our best winters have been neutral ENSO years. It's a few years old but it still applies.

 

  • Like 1
  • Thanks 1

Share this post


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

 

Is that a typo for October 31st?

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...