Jump to content
  • Forum Image
NorthGeorgiaWX

Wednesday, January 1 - Happy New Year!

Recommended Posts

Good morning and Happy New Year!

I hope no one has a hangover! I managed to sleep like a baby right into the new year! 🙂  It's tough staying up past 9 pm when you're just a little kid. 😜

You can see the moisture beginning to stream in from our next weathermaker out over the southwest US, and that system will be bringing some heavy rain for our friends up in the NW corner of the state.

Snap346063300.thumb.png.af566f607d33ef076fec176c2299b239.png

 

Here is the NWS Atlanta discussion:

Quote

As the upper trough amplifies across the central Conus and phases
with a lobe of energy farther south, Gulf moisture transport will
greatly increase across the western and northern CWA throughout the
day Thursday. Have slight to chance pops for showers across the
western and northern majorities beginning with initial isentropic
upglide and warm frontal progression Thursday morning, then ramp up
to likely and categorical pops through the day mainly along and west
of the I-85 corridor.
Some showers could be quite efficient given
the high PWAT regime of near or above 1.5 inches and potential
training.
With increased WPC QPF storm totals maxing out to 3-4
inches in the far NW and inclusion of a Day 2 Slight to Marginal
Excessive Rainfall Outlook
, have coordinated with northern
neighboring offices to issue a Flood Watch
. This extends along and
northwest of a Rome to Fairmount to Chatsworth line from Thursday
afternoon through Friday, and may end up being extended farther
eastward in future updates.

 

Here is the watch map at the moment.  http://www.daculaweather.com/4_alert_map.php

1993204641_MapImage(2).jpg.7e37fb972e2c753864f71f229de9fb9f.jpgMapLegend.jpg.777beea8f944845086fe10ba3169b38b.jpg

image_full1.thumb.png.3e428c532d50b8cff7ca5d61556f316c.png

 

And as you have read, the WPC has placed part of the NW corner of the state in a "Slight" and "Marginal" risk area for excessive rainfall and this is their discussion:

Quote

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
308 AM EST Wed Jan 01 2020
 
Day 2
Valid 12Z Thu Jan 02 2020 - 12Z Fri Jan 03 2020 

  • THERE IS A SLIGHT RISK FOR EXCESSIVE RAINFALL OVER PORTIONS OF THE GULF STATES AND TENNESSEE VALLEY

Bands of moderate to heavy rain will overspread the Gulf states 
the Tennessee Valley as a surface low pressure and associated 
fronts lift north and east out of the Gulf of Mexico.   
Precipitable water values around 1.25/1.5 inches (anomalies of +2 
to +3 standard deviations) along with instability will be drawn 
northward and pool over much of the Gulf states and the Southeast 
U.S. prior to and during the day 2 period. Model consensus 
continues to suggest  areal averages of 2.50 to 5 inches
from 
south-central Louisiana to northeast Tennessee, with the maximums 
focused over central Mississippi and northern Alabama.
Within this 
deep plume of moisture there will be marginal instability 
(generally near 500 J/KG of MUCAPE) extending from the Gulf of 
Mexico into LA and central MS/AL. 

As the long wave trough moves east, it should keep the developing 
line of low topped convection mostly progressive. There should be 
a window when local training could occur as cells move northeast 
along the eastward moving line. The placement of the highest 
rainfall would be were training might occur (Mississippi and 
Alabama) so these amounts seem plausible. 

Three hour flash flood guidance values are generally above 2.50 
inches (though portions of  MS/AL/TN have seen 200+ percent of
normal rainfall over the past 14 days), so training would be needed
to initiate flash flooding. 

The ongoing Slight and Marginal Risks remain in good standing with 
only minimal adjustments made for the latest WPC QPF.

Campbell

98ewbg.gif.5b282f05c0ffd5c5b840048c6709980c.gif

 

The precip forecast looks like this and is subject to change. The WPC forecast is on the left and the NDFD forecast on the right, and they seem to be in pretty good agreement. 

wpc-atlanta-total_precip_inch-8225600.thumb.png.061f87d28ba3fc1854ea3775e756135e.pngndfd-conus-atlanta-total_precip_inch-8096000.thumb.png.f368019aba17c7da46c628194aef1d3b.png

 

The 6 hour Flash Flood Guidance says that the NW corner needs >2.0-2.5" over a 6 hour period before flooding starts to occur,. I have all the FFG maps at this link. http://www.daculaweather.com/4_flash_flood_guidance.php If you live in these areas, stay alert to any warnings that may get issued and remember, Turn Around, Don't Drown.

FFG_6HR.png.e218ffa3dfbeb06c3f77bf9f6c80fd14.png

 

As the rain starts to wind down on Saturday, colder air will be filtering in behind the front, and lingering moisture may fall as a rain/snow mix or even all snow before ending. We will have another minor chance on Wednesday.

Quote

SATURDAY NIGHT
Model guidance is also forming some
wrap- around precip for far northeastern Georgia Saturday Night,
perfectly timed with the upper-level trough axis which will cool
low-level temps enough for some very light snow flurries.

WEDNESDAY
Despite a mix of cooler temps and precip, if winter weather forms for far
north Georgia, it would be early Wednesday morning...according to
the GFS solution...but no accumulations are expected given how
much variance and little confidence the Day 6-7 forecast holds.

 

The 00Z GFS and Euro look like this through Sunday morning.
 gfs-deterministic-atlanta-total_snow_10to1-8225600.thumb.png.89fb5ed9bd17c178d290efb373e8709a.pngecmwf-deterministic-atlanta-total_snow_10to1-8225600.thumb.png.4b9e3083b729d02a07fd3d9b428f0ee0.png

 

The new 06Z GFS that is just in looks like this.
896286140_gfs-deterministic-atlanta-total_snow_10to1-8225600(1).thumb.png.3be52ea4d6cee65fd7101e5316843491.png

 

The GFS ensembles are even beginning to agree on the potential for a little bit of snow. Here are a few sites around the top of Georgia. Notice the two humps in the lower graphs of all the images. That is an indication of two events. And actually I see 3 humps in the graphs... 😉 

gfs-ensemble-all-KCNI-indiv_snow-7836800.thumb.png.c11e0f5a91a1ed2fcf6c6791f3634778.pnggfs-ensemble-all-KDNN-indiv_snow-7836800.thumb.png.c2815fbb8bcfcc5615b5e387edffa358.png

gfs-ensemble-all-KDZJ-indiv_snow-7836800.thumb.png.ea2f0a5815db744eeaf304efe949e2b3.pnggfs-ensemble-all-KCHA-indiv_snow-7836800.thumb.png.8ecf2dd17889f4d44fa08050eb68b41e.png

 

So while the chances aren't great and it doesn't cover everyone, I'm tryin' to get you a little snow. 🙂

Enjoy this first day of the New Year! Lots of bowl games on today with Georgia tonight at 8:45 PM, so it's going to be another long day! 🙂 Hope is a great one for you!

forecast-01.png.b19981a940d3736fd906427645e73872.pngSnap346063302.png.732978c8cb7eb48688a327be25fe7f99.png

  • Like 2

Share this post


Link to post
Share on other sites

Just looking at the latest 06Z Euro. This is going to be a deep upper level low passing over us this weekend that will make its own cold air. These can surprise those folks that are lucky enough to be underneath it. 

Here a look at temperatures from 925 mb to 500 mb. All support snow. However the surface temperatures are a little above freezing, so impacts will be minimal to non-existent.

ecmwf-deterministic-se-t925-8182400.thumb.png.49a88a0d01df4ca5f0a19f3c1fd25dd1.png

ecmwf-deterministic-se-t850-8182400.thumb.png.53340d5ecdf229947bc32b57f0b2de29.pngecmwf-deterministic-se-t700-8182400.thumb.png.ec0c198910c2ff3ddcc5c894dce62394.pngecmwf-deterministic-se-t500-8182400.thumb.png.65b740211d8b7d5fd696c681473b2ca7.png

 

Thicknesses support snow.

ecmwf-deterministic-se-thck_1000-500-8182400.thumb.png.f863583b492619ee411a6394603d4256.pngecmwf-deterministic-se-instant_ptype-8182400.thumb.png.0aa67ca1dc7405465168af06f5a2e381.png

 

As of 7 PM Saturday, this run compared to the previous 00Z run is a little stronger. 06Z on the left, 00Z on the right.

Snap346063311.thumb.png.dd030e4737a55351cc2b6544b1dc39f7.png

  • Like 2

Share this post


Link to post
Share on other sites

Question about the system coming up next 2 days. It always interests me when the forecasts dramatically change. What changed in the system to go from 1-3 inch proj to 3-6 inch projected rain totals now in one day ( overnight really)basically? 

  • Like 2

Share this post


Link to post
Share on other sites
23 minutes ago, RickyD said:

Question about the system coming up next 2 days. It always interests me when the forecasts dramatically change. What changed in the system to go from 1-3 inch proj to 3-6 inch projected rain totals now in one day ( overnight really)basically? 

Once you start getting close, the model accuracy goes up considerably. That's one reason to NEVER trust the deterministic models until you're within 3-4 days, and even then there is no guarantee. When the pieces start falling into place, things can change quickly, once you get a little closer to the time the changes become smaller and smaller. 

  • Like 1

Share this post


Link to post
Share on other sites

Very interested in the 7th possibility. It's a long shot, but at least with it the cold would already be in place. Vort would have to dive hard though in order to round the bend in time and not be a late bloomer off the coast. Would probably be nothing more than a light finger of precip sliding across but at this point I'll take anything. 

  • Like 3

Share this post


Link to post
Share on other sites

Not that it's surprising, but Euro is not really playing along with the 7th chance. Plenty of moisture but all the cold from this weekend is already gone. 

It also significantly cut down on lingering moisture this weekend as well. Even the smokies barely see an inch on that run. 

  • Like 1

Share this post


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

 

Well the Pacific NW should be set to working on reversing their snow drought soon. Not so much in the Mid-Atlantic and Southern Appalachians... I keep looking for reasons for hope on the ensembles but coming up empty. PNA going to be a serious thorn in our sides for potentially a long while. 

  • Like 3

Share this post


Link to post
Share on other sites

But of course, in trying not to be a complete debbie downer, the thing we all are wishing for is snow, not cold. No the pattern doesn't look very favorable for any lasting cold through most of January, but we don't necessarily need it for a snow storm, just good timing. 

  • Like 3

Share this post


Link to post
Share on other sites
14 hours ago, KingOfTheMountains said:

But of course, in trying not to be a complete debbie downer, the thing we all are wishing for is snow, not cold. No the pattern doesn't look very favorable for any lasting cold through most of January, but we don't necessarily need it for a snow storm, just good timing. 

Actually to be honest I love snow, but it is such a rare occurrence especially for the Athens area I would be okay for just a seasonal winter season with normal temperatures! We sweat enough in our Brutal summers! What used to be 3 months is now 4-5 months! Nature needs some cold in the winter season especially Northern Georgia! This will be potentially 5 warm winter seasons in a row! Very warm winters also! Maybe a record? Steve your input?

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.


  • Who's Online   0 Members, 0 Anonymous, 2 Guests (See full list)

    There are no registered users currently online



×
×
  • Create New...