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Potential for Snow on Thursday, Bitter Cold Possible Next Week

Possibly the coldest temperatures in 2-3 years on the way.

Thought it was time for Part II about the colder weather. What cold weather you ask? Take a look back at my last blog post if you haven't read it and then return here. There I talked about the SSW (Sudden Stratospheric Warming) and its impact on our weather was well as a little bit about the needed blocking in order to get the cold air here.

The stratospheric warming has (actually still is) done its thing, so the stage is set. Everyone wants to know what's going to happen next, so let's take a look at what is coming down the road. I wish the Patch would let us use inline images to show you, but they don't, so I'll include links to the images and pages I'm referring to.

We have several things happening right now. A positive tilt upper level trough over the 4 corners region is creating some icy conditions over Texas right now and this system is forecast to move east and then northeast over the next several days. There is considerable disagreement among the models about how this system is going to evolve, but several models show this coming across the southeast with some form of winter precipitation for some areas (several models are showing this), and of course, those are unknown areas right now. It's a marginal system for winter weather at this time due to a lack of cold air support, but the models appear to be missing out on what may become a closed upper level low, and if this comes to fruition, it would have major consequences for the southeast. Thursday night would be about the time this system would effect our area, so we have a few days to track it and watch for any signs of development that may cause issues for us.

Update: A Special Weather Statement has been issued by the Atlanta NWS office this afternoon about this system:

...WINTER WEATHER POSSIBLE ACROSS NORTH GEORGIA ON THURSDAY... A STRONG LOW PRESSURE SYSTEM WILL MOVE ACROSS THE STATE ON THURSDAY. AHEAD OF THE SYSTEM... A DEEP SOUTHERLY FLOW WILL SPREAD AMPLE GULF MOISTURE NORTHWARD... RESULTING IN WIDESPREAD RAIN ACROSS NORTH AND CENTRAL GEORGIA. AS THE ASSOCIATED COLD FRONT PUSHES INTO THE CAROLINAS THURSDAY AFTERNOON... A DEEP COLD AIR MASS WILL BEGIN TO SPREAD INTO THE AREA FROM WEST TO EAST THURSDAY AFTERNOON AND EVENING. AS A RESULT... THERE IS A POTENTIAL FOR RAIN TO CHANGE OVER TO SNOW ACROSS PARTS OF NORTH GEORGIA IF SUFFICIENT WRAP AROUND MOISTURE CAN SPREAD BACK INTO THE COLD AIR MASS BEHIND THE DEPARTING COLD FRONT. DESPITE WARM GROUNDS FROM RECENT UNSEASONABLE WARM TEMPERATURES... THERE IS THE POTENTIAL THAT STRONG UPPER FORCING COULD ENHANCE SNOWFALL RATES ENOUGH TO ALLOW FOR SOME LIGHT SNOW ACCUMULATIONS ACROSS PARTS OF NORTH GEORGIA BY MID TO LATE THURSDAY AFTERNOON OR EARLY EVENING... BUT THIS WOULD BE MAINLY OVER ELEVATED AND GRASSY SURFACES. ALTHOUGH LIGHT SNOW COULD BE SEEN AS FAR SOUTH AS A LA GRANGE TO ATHENS LINE... IT APPEARS THE GREATER CHANCES FOR SNOW ACCUMULATION WOULD BE GENERALLY NORTH OF THE I-20 CORRIDOR WEST OF ATLANTA... AND THE I-85 CORRIDOR EAST OF ATLANTA. AT THIS TIME... NO WIDESPREAD TRAVEL DIFFICULTIES ARE EXPECTED WITH THE INITIAL SNOWFALL THURSDAY AFTERNOON AND EARLY EVENING... EXCEPT POSSIBLY IN THE NORTHEAST GEORGIA MOUNTAINS WHERE THERE IS A GREATER POTENTIAL FOR HIGHER SNOW ACCUMULATIONS. HOWEVER... THERE IS A POTENTIAL FOR PATCHES OF BLACK ICE DEVELOPING ON BRIDGES AND OVERPASSES FROM LATE THURSDAY EVENING THROUGH MID FRIDAY MORNING WHEN TEMPERATURES FALL BELOW FREEZING. ALL INTEREST ACROSS NORTH AND CENTRAL GEORGIA SHOULD CONTINUE TO MONITOR LATER FORECASTS AND REMAIN ALERT FOR THE POTENTIAL OF WINTER WEATHER THURSDAY AFTERNOON AND THURSDAY NIGHT.

Right now, the country has an expansive area of very cold temperatures under a shallow arctic high pressure system. The cold front responsible for the colder weather is still draped to our west in a SW-NE line, and over the next few days this front is forecast to push on through our area and bring us down to below normal readings for a few days. Don't be fooled though, this isn't the REAL cold air, that is still bottled up in central Canada for now. 
The long range models (CFSv2) are showing well below normal temperatures for February for the east half of the country, and below normal precipitation for most almost the entire country. They have been insistent at this occurring and it appears to be beginning to push it's way south. It terms of blocking patterns (called teleconnections), the AO (Arctic Oscillation) is forecast to tank with extremely negative readings. The negative AO tells us that the polar vortex is weakened and cold air is being forced south toward the mid-latitudes, all the result of the SSW or Sudden Stratospheric Warming (several links here 1 | 2 | 3 | 4 | 5 ) that just took place about a week ago. The NAO (North Atlantic Oscillation) has been positive for a week or two but now looks to drop solidly into the negative territory toward the end of the month. We need a west-based NAO near Greenland to effectively block the cold air from retreating to the east instead of dropping south. One of the biggest thorns in our side this winter has been the +PNA (Pacific North American Oscillation) which has poured warm moist Pacific air into the country in a zonal type flow. Now... this is changing too. I'll mention one other piece of the puzzle, the MJO (Madden-Julian Oscillation). The MJO is a complex subject, but basically when the MJO goes into 1 of the 8 phases, there are certain temperature correlations that can be made for various areas of the country. Right now the models are moving the MJO toward Phase 8 pretty rapidly which is a sign of cold weather for the east half of the country. At the bottom of the MJO page, you'll see each of the 8 phases and how the temperatures respond in any particular phase.

So what does all of this mean? Cold with the possibility of bitter cold for some areas. We could possibly see our coldest temperature in 2-3 years in Georgia with this arctic outbreak. It appears that the next big push of cold air will be entering the country in six days (20th-21st) and maybe 10 ( 24-25th) before we feel the real effects from it. This still fits into my original thoughts of the 20-24th of January. 

I like the cold we currently have over the middle of the country, it's helping to cool the ground before the next round, that way the next batch won't moderate as much as it would have done over warmer ground. I like several maps you can use to follow the temperature trends.

  • 24 temp change
  • Hourly temperature contour maps
  • Google Map - On this map click on "Station Markers" and make sure the type is set to Temps.
  • 00Z and 12Z Loops - I'm building these loops daily. I'm capturing the temperature contour map daily at 00Z and 12Z (7pm and 7am respectively) and building a loop for them. These loops started last Wednesday the 9th and I will continue these through the winter. Each frame of the loop is 24 hours from the previous frame so you get a nice comparison of temps as the winter progresses. 
  • MESONET conditions 


Precipitation is obviously not as prevalent when you get really cold temperatures as the cold air dries things out. But the south is one area where the precip will not be too far below normal and that bodes well for winter precipitation over the southeast. It's all dependent on how far the cold air pushes south and as always in the southeast, we walk a tightrope in getting snow here. 
Bottom line is this. Arctic air is poised to dive south from Canada over the next two weeks and take us from well above normal temperatures to well below normal. It's too early to tell about any form of winter precipitation (even for Thursday!) yet and that will be one of the things that we will be tracking for you. And as always, you'll hear it first here!

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Lori January 17, 2013 at 05:59 PM
Could we have some light snow? Maybe on grassy surfaces?
North Georgia Weather January 17, 2013 at 06:09 PM
Oh yes, not saying it NOT going to snow... it most likely will. But if the low moves much further north it would be much quicker and lighter. Snowing over 2/3's of Alabama right now...
Lori January 17, 2013 at 06:42 PM
Thank you! I'm from South Florida and haven't seen much snow before. What time frame do you think for Gwinnett County?
North Georgia Weather January 17, 2013 at 06:49 PM
Right now I'm thinking around 6-7pm, that may change. Watch this radar loop for signs of snow. This is Dual Pol data from the Atlanta NWS radar in Peachtree City. This particular loop can distinguish between rain and snow and ice. Light blue is dry snow, dark blue is wet snow, and pink is ice. http://www.daculaweather.com/grlevel4/4_ffc_hhc.php Also, here's what the Birmingham image looks like right now http://www.daculaweather.com/images/2013_01/bmx_snow.png
North Georgia Weather January 17, 2013 at 07:14 PM
Temperatures falling at 6º/hr here now and currently at our low for the day.
North Georgia Weather January 17, 2013 at 07:21 PM
Down to 43º F here and falling at more than 6º/hour.
North Georgia Weather January 17, 2013 at 08:12 PM
The Winter Storm Warning is creeping south toward us. .FFC WATCHES/WARNINGS/ADVISORIES... WINTER STORM WARNING UNTIL 7 AM EST FRIDAY FOR THE FOLLOWING ZONES: BARTOW...CATOOSA...CHATTOOGA...CHEROKEE...DADE...DAWSON... FANNIN...FLOYD...GILMER...GORDON...LUMPKIN...MURRAY...PICKENS... TOWNS...UNION...WALKER...WHITE...WHITFIELD. IN GENERAL...EXPECT 2-4 INCHES OF SNOW...WITH ISOLATED AMOUNTS UP TO 5 ACROSS FAR NORTH GEORGIA...AND SMALLER AMOUNTS ACROSS THE NORTH METRO AREA.
North Georgia Weather January 17, 2013 at 08:13 PM
MAIN AREA OF RAIN SHOWERS ON ITS WAY INTO THE CAROLINAS THIS AFTERNOON...AND AREA OF WINTER PRECIP ASSOCIATED WITH UPPER LOW EXPECTED TO PASS OVER NORTH GEORGIA TONIGHT. WINTER PRECIP IS GENERALLY EXPECTED NORTH OF A HAMILTON TO WASHINGTON LINE...BUT ACCUMULATIONS SHOULD BE LIMITED TO A LINE NORTH OF CARROLLTON TO ATLANTA TO JEFFERSON. IN GENERALLY...EXPECT 2-4 INCHES OF SNOW...WITH ISOLATED AMOUNTS UP TO 5 ACROSS FAR NORTH GEORGIA...AND SMALLER AMOUNTS ACROSS THE NORTH METRO AREA. EXPECT INITIAL PRECIPITATION TO BE A MIX OF RAIN AND SNOW...THEN TRANSITIONING TO A WET SNOW. WARM SURFACE TEMPERATURES SHOULD KEEP ACCUMULATIONS LIMITED AT FIRST...BUT CONVECTIVE NATURE OF THE PRECIP SHOULD OVERCOME THE WARM SURFACE TEMPERATURES. EXPECTING HEAVIEST SNOWFALL OVER FAR NORTHEAST GEORGIA WHERE BANDING AND POTENTIAL TERRAIN ENHANCEMENT WITH THE WIND TRAJECTORY ARE EXPECTED TO INCREASE SNOWFALL TO THE ISOLATED 5 INCH AMOUNT.
North Georgia Weather January 17, 2013 at 08:18 PM
Gwinnett is right on the line for 2-4". Wouldn't take much to get us a decent little snow at this point.
Terrie R January 17, 2013 at 08:37 PM
Really? I thought we were in the warm bubble and would not get much. So we could be looking at some real snow.
North Georgia Weather January 17, 2013 at 08:41 PM
Yes, I said that, and yes, we were going to be... and still might be. But the NWS has been bumping up accumulations this afternoon so the potential exists for some minor accumulations here. Wouldn't surprise me to see some flakes in a little while.
North Georgia Weather January 17, 2013 at 08:41 PM
This afternoon when I was outside around 3pm, we had some very light snow flakes flying around.
North Georgia Weather January 17, 2013 at 08:56 PM
A little snow reported in Villa Rica a few minutes ago.
Bob M. January 17, 2013 at 10:02 PM
FWIW, with all this rain, Lake Lanier is up a bit over 2' since 1/1/13 and over 4' in the last month. http://lanier.uslakes.info/Level.asp
North Georgia Weather January 18, 2013 at 12:42 AM
Guys... I hate to say it, but it's not looking good for us. There are small bands of precipitation moving in but it is light and diminishing in coverage. There are some wet flakes mixed in and you may get all snow for a little while. Here's an image of where the upper low is now. You'll see how we missed the mark. http://www.daculaweather.com/images/2013_01/500mb_low.png
Sharon Swanepoel January 18, 2013 at 12:50 AM
Yea, it just looks wet and soggy here! Nothing pretty and white!
Tommy Hunter January 18, 2013 at 01:17 AM
The moon and stars are never as pretty, nor the skies so clear as when some form of winter weather alert is issued. LOL Really is nice to see them. Another big swing and a miss. Does this mean we are in store for those mid-60's next weekend?
R++ One of the Famous Dacula Crew January 18, 2013 at 01:21 AM
Mr Hunter there are more than just a few "flakes" in Braselton...
North Georgia Weather January 18, 2013 at 11:25 AM
No, we missed the mark. From the beginning it didn't appear that much would happen here. It went back and forth yesterday, but once it started to lift north we were doomed. The mountains killed any wrap-around moisture on the backside of the storm. Again, it's all about the track, in the winter here in Atlanta, we need the low to track along the Gulf coast in order to get a snow storm here and this one went directly over us. We were hoping for better dynamics over our area but as the upper low moved over the 850 mb temps actually warmed. We lost the dynamics and North Carolina got slammed with thundersnow. Of course. As far as the upcoming weather... EXTENDED FORECAST DISCUSSION NWS HYDROMETEOROLOGICAL PREDICTION CENTER COLLEGE PARK MD 155 AM EST FRI JAN 18 2013 VALID 12Z MON JAN 21 2013 - 12Z FRI JAN 25 2013 NEXT WEEK BEGINS WITH QUITE AN AMPLIFIED PATTERN FOR THE NATION HIGHLIGHTED BY STABLE MID-UPPER LEVEL WEST COAST RIDGING AND A WELL CARVED AND QUITE COLD DOWNSTREAM EAST-CENTRAL MID-UPPER LEVEL TROUGH. IT DOES NOT LAST. THE PATTERN BREAKS DOWN SURPRISINGLY QUICKLY BY GUIDANCE AS PROGRESSIVE ERN PACIFIC TROUGH ENERGY/WEATHER CRASHES INLAND THROUGH THE WRN US RIDGE POSITION BY MIDWEEK AND SUBSEQUENTLY ACTS TO SIGNIFICANTLY WARM LEAD DOWNSTREAM CENTRAL TO ERN US TEMPS AND ALLOW EVENTUAL INCREASE OF MOISTURE AVAILABILITY AND WIDESPREAD/ORGANIZED PCPN POTENTIAL...ALBEIT A WEEK AWAY.
North Georgia Weather January 18, 2013 at 11:40 AM
From Robert Gamble about what went wrong down here: "Basically, the cold was too thin for that area, and too late to arrive, and the upper low was speeding up, which further reduced the already short window of opportunity there. Without cold air firmly in place, it's always a risky proposition that many times won't work out right."
North Georgia Weather January 18, 2013 at 11:41 AM
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE PEACHTREE CITY GA 639 AM EST FRI JAN 18 2013 ...ISOLATED PATCHY BLACK ICE POSSIBLE ACROSS PORTIONS OF NORTH GEORGIA THIS MORNING... SOME ISOLATED SPOTS OF PATCHY BLACK ICE...MAINLY ON BRIDGES AND OVERPASSES ARE POSSIBLE THIS MORNING ACROSS PORTIONS OF NORTH GEORGIA. MOTORISTS SHOULD SLOW DOWN AND PROCEED WITH CAUTION.
North Georgia Weather January 18, 2013 at 11:44 AM
Here's a summary of the winter storm. It also list snowfall amounts so you can see where the snow actually fell. http://www.daculaweather.com/4_hpc_winter_storm_summary.php
North Georgia Weather January 18, 2013 at 12:02 PM
Tommy , the models are showing a quick shot of arctic air this weekend after a warm up Fri/Sat. After that, the high moves out to sea in a more zonal flow. Right now the blocking is just not in place to produce a prolonged cold outbreak. The models are are showing a breakdown of the Pacific ridge which would allow warm and moist Pacific air back into the picture. I think we'll see intermittent shots of cold air until/if ridging can get established. February is still looking below normal in the long range CFSv2 models.
Tommy Hunter January 18, 2013 at 02:08 PM
So basically, all that talk they were doing last week about a split in the polar vortex and a lot of cold air was simply BS trying to fill in an otherwise boring weather news week? Appears again to be a winter that wasn't. And you were exactly right when you were saying the type "storm" they were predicting yesterday never works out. I'm good with that. I've seen enough snow this year already.
North Georgia Weather January 18, 2013 at 02:15 PM
Not really. The strat warming has brought about changes, the extent of the changes are still to be seen. I'll have a new post tonight about the longer range outlook.
Terrie R January 18, 2013 at 02:22 PM
Tommy, where are you that you have seen snow this year?
Tommy Hunter January 18, 2013 at 05:53 PM
I was in Nebraska on a hunting trip in November. Cold and snowy.
North Georgia Weather January 18, 2013 at 08:31 PM
A quote from meteorologist Allan Hoffman today. Allan graciously allows me to display his model images on DaculaWeather.com. Allan works for the Raleigh Examiner and is very knowledgeable about southeast weather. "The ensemble guidance wants to pop a –EPO ridge into the Gulf of Alaska and build it into western North America as that week progresses, which should progress the trough out, and at the same time we see continued positive height anomalies over the poles (blocking). The ensembles are in pretty good agreement today that the trough will move into the Plains/Midwest by 1/29-1/30 and cover much of the eastern half of the nation by 1/31 into early February. The look of the ensembles is pretty cold late in the 11-15 day period. We see a –AO, a –NAO, and a ridge over the west coast of North America. This sets up the polar vortex over Hudson Bay and a cold pattern across much of the eastern half of the nation. This is supported by the latest CFS and ECMWF weekly forecasts which keep a cold pattern through mid-February. So perhaps there will be more snow chances for many of us in the month of February."
North Georgia Weather January 18, 2013 at 08:37 PM
Great image of where the snow did fall http://www.daculaweather.com//images/2013_01/snow_google.jpg
North Georgia Weather January 18, 2013 at 08:42 PM
From another meteorologist friend. Jason lives in Dahlonega and said this around 8am this morning: "For the GA peeps I have a clear view of Woody Gap (3,300 ft), Blood Mountain (4,000 ft) and the mountains north of Helen GA. I see no snow anywhere."

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