White Christmas in Atlanta????

[JenyEliza]

White Christmas? Snow possible Sunday night
By MIKE MORRIS
The Atlanta Journal-Constitution
Published on: 12/20/05

Santa might need his rain gear when he makes his rounds through metro Atlanta Saturday night, but forecasters at the National Weather Service are hinting at a chance of snow by late Christmas night.

If the forecast holds true, it would be the 15th time that snowflakes have officially fallen on Atlanta on Dec. 25 since record-keeping began in 1896.

The last Christmas snowfall occurred in 1993, when flurries fell for about an hour during the afternoon but melted on contact.

Atlanta has never, however, had a measurable accumulation of snow on Christmas.

Maybe this is the year.

The National Weather Service is forecasting a "decent chance" of rain on Christmas Eve and overnight into the big day.

"It gets a bit tricky Sunday afternoon and Sunday night ... behind a cold front," the Weather Service said.

"The bulk of the precipitation will have moved well to our east; however, wraparound moisture will spread over North Georgia late Sunday afternoon and Sunday night," the Weather Service said. "It is possible to see a mixed bag of precipitation Sunday afternoon."

The Weather Service said Sunday night is "a different story ... any precipitation that does fall will be in the form of light snow."

The forecast for the rest of the week calls for partly cloudy skies and lows in the upper 20s tonight.

Wednesday through Friday should be mostly sunny, with afternoon highs warming from the upper 40s on Wednesday to the upper 50s by Friday and overnight lows in the mid- to upper 20s.

A 40 percent chance of rain is forecast for Saturday, when highs will be in the upper 50s.

Christmas Eve night will be cloudy, with a 60 percent chance of rain and lows in the upper 30s.

Mostly cloudy skies and a 50 percent chance of rain are forecast for Sunday.

Sunday night, things get interesting, with a forecast that calls for a 30 percent chance of light snow and lows in the low 30s.

Any snow should end by Monday morning, the Weather Service said.

[Brent]

I got you on the bandwagon...

Snow cancel.

Seriously, we're down to 5 days now which makes the forecast more reliable. I'm not sold yet, but I think some flurries are defintely possible.

[JenyEliza]

LONG TERM...(THURSDAY NIGHT THROUGH MONDAY)
FLOW BECOMES ZONAL OVER THE CWA FRIDAY WHICH WILL CONTINUE TO MODERATE TEMPS. THE NEXT SIGNIFICANT S/W WILL MOVE INTO THE CWA THIS WEEKEND. THIS S/W WILL DEEPEN AS IT MOVES INTO THE SOUTHEAST U.S. AHEAD OF THE S/W TEMPS WILL BE MILD FOR THIS TIME OF YEAR ALONG WITH A DECENT CHANCE OF RAIN SATURDAY AND SATURDAY NIGHT. IT GETS A BIT TRICKY SUNDAY AFTERNOON AND SUNDAY NIGHT AS LOW LEVEL THICKNESSES DROP SIGNIFICANTLY SUNDAY AFTERNOON BEHIND THE COLD FRONT AS WELL AS STRONG CAA AT H8. BY 00Z MON H8 TEMPS OVR ATL ARE NEAR ...2C. THE BULK OF THE PRECIP WILL HAVE MOVED WELL TO OUR EAST...HOWEVER WRAP AROUND MOISTURE WILL SPREAD OVER NORTH GA LATE SUNDAY AFTERNOON AND SUNDAY NIGHT. IT IS POSSIBLE TO SEE A MIX BAG OF PRECIP SUNDAY AFTERNOON BUT GIVEN THAT THIS IS DAY 6 AND THERE WILL CONTINUE TO BE TIMING PROBLEMS UNTIL WE GET CLOSER TO THAT DAY I WILL ONLY MENTION RAIN DURING THE DAY SUNDAY. SUNDAY NIGHT IS A DIFFERENT STORY AS LOW LEVEL THICKNESS PATTERNS AND H8 TEMPS SUGGEST THAT ANY PRECIP THAT DOES FALL WILL BE IN THE FORM OF LIGHT SNOW. WILL THEREFORE MENTION A CHANCE OF SNOW SUNDAY NIGHT. STRONG CAA CONTINUES INTO MONDAY WITH DRYING CONDITIONS. THIS WILL GIVE US MUCH COOLER TEMPERATURES ALONG WITH GUSTY NORTHWEST WINDS.

And

Christmas Day: A 50 percent chance of rain. Mostly cloudy, with a high around 47.

Sunday Night: A chance of snow. Mostly cloudy, with a low around 32. Chance of precipitation is 30%.

[JenyEliza]

I got you on the bandwagon...

Snow cancel.

Seriously, we're down to 5 days now which makes the forecast more reliable. I'm not sold yet, but I think some flurries are defintely possible.

Oh....I know...5 days out is nothing to hang your hat on. It's just fun to think we might see snow on Christmas.

[jizzy]

Hey the NWS is now starting to say the S word for Nashville Area but I know that won't happen : / never does



AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NASHVILLE TN
439 AM CST TUE DEC 20 2005

.SHORT TERM...A COLD CANADIAN HIGH PRESSURE SYSTEM SETTLED IN
ACROSS MIDDLE TENNESSEE OVERNIGHT, WITH DEWPOINTS DROPPING TO
BETWEEN 8 AND 14 DEGREES AND TEMPERATURES FALLING INTO THE TEENS.

EXPECT HIGH PRESSURE RIDGE TO MOVE GRADUALLY EASTWARD TODAY AND
TOMORROW AND BE NEAR THE CUMBERLAND PLATEAU BY 00Z THURSDAY. THEREFORE,
EXPECT MORE COLD WEATHER TODAY AND TONIGHT AND BELIEVE MET MOS,
WITH ITS DRIER AND COLDER SECOND PERIOD TEMPERATURES TO BE MORE ON
TARGET. THUS, AM UNDERCUTTING MAV MOS BY AT LEAST 5 DEGREES TONIGHT.

.LONG TERM...THE WEATHER STARTS TO GET INTERESTING AS WE HEAD INTO
THE CHRISTMAS WEEKEND. A COLD FRONT MOVES IN LATE FRIDAY NIGHT AND
SATURDAY AND PRODUCES A CHANCE FOR RAIN SHOWERS. MOST GFS RUNS OVER
THE LAST 24 HOURS HAVE INDICATED A DEEPENING TROUGH ASSOCIATED WITH
THIS COLD FRONT AND THERE HAVE BEEN REPEATED INDICATIONS THAT THE 50H
LOW CENTER WILL SWING THROUGH THE TENNESSEE VALLEY, AND POSSIBLY
AS FAR SOUTH AS NORTHERN PARTS OF THE GULF STATES. ALTHOUGH COOLING
WILL BE GRADUAL BEHIND THE COLD FRONT, UNDER CLOUDY SKIES, BELIEVE
TEMPERATURES WILL FALL STEADILY SATURDAY NIGHT AND SUNDAY AND BY
SUNDAY AFTERNOON AND SUNDAY NIGHT EXPECT SOME PARTS OF THE MID STATE
TO SEE TEMPERATURES AT LEAST IN THE MIDDLE 30S, AND EITHER A BRIEF
PERIOD OF MIXED PRECIPITATION OR, POSSIBLY, EVEN A FEW HOURS OF
WET SNOW AT SOME POINT. REGARDLESS OF THE PRECIPTIATION TYPE, EXPECT
GROUND TEMPERATURES TO BE WARM ENOUGH TO LIMIT THE POSSIBILITY OF
ACCUMULATION EXCEPT, PERHAPS, ALONG THE CUMBERLAND PLATEAU LATE SUNDAY
AND SUNDAY NIGHT. OF COURSE, THIS PRECIPITATION EVENT IS STILL 5
DAYS AWAY AND COULD TURN OUT TO BE AN ALL-RAIN EVENT, DEPENDING UPON
THE STRENGTH OF THE UPPER TROUGH AND THE ACTUAL TRACK OF THE 50H
CENTER. NEVERTHELESS, WITH REPEATED MODEL TRENDS POINTING TOWARD
THE POSSIBILITY FOR AT LEAST A BRIEF PERIOD OF MIXED PRECIPITATION,
HAVE GONE AHEAD AND TRENDED THINGS COLDER FOR THE WEEKEND AND
INTRODUCED THE S-WORD.
[/quote]

[Brent]

I love the GFS...

How about some heavy rain Christmas Morning?



Heck, looking at that, we might just as easily have a tornado outbreak.

[jizzy]

Hey don't mock it LOL it might happen ! LOL but it is the GFS

[Brent]

I just want to make one point...

Upper Level Low Christmas Night...(which means the maps with temperatures on them are useless since they bring their own cold air).

Upper Level Low caused the surprise White Christmas in South Texas last year

Upper Level Low's have given us numerous surprise snows in the past.

[BreinLa]

Keep me up to date guys I will be in Nashville this weekend and would love to see some SNEAUX

[jizzy]

I can pretty much tell you that it won't snow , Nashville always seems to be on the SNOW/Rain line .. We always get hit when they are not forecasting it .

[Brent]

We jinxed it... 0z run, cold, but no snow.

[JenyEliza]

Maybe not, Brent. Check this out from FFC (btw...I've noticed much more detailed AFD's from SNelson since the ice-storm two weeks ago where the performance from FFC was not quite up to snuff--ie, 10 hours and no AFD's, etc).

Seems the NWS Gateway computer was down, so data is incomplete, per this AFD.

Maybe all is not lost?

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
944 PM EST TUE DEC 20 2005

.UPDATE...
PREV FCST SEEMS TO BE GOING AS PLANNED. SOMEWHAT DRIER ACROSS NW 1/2 OF CWA TONIGHT THAT GUIDANCE ADVERTISED. CURRENT DEWPOINTS AT 9PM INCLUDE 10 AT HARTSFIELD (KATL) AND 7 AT CANTON (K47A). THIS COULD INDICATE WE COULD REACH RED FLAG CRITERIA WEDNESDAY AFTERNOON. WILL NOT ISSUE WATCH ATTM AS CURRENT FWF HIGHLIGHTS POSSIBLE RISK OF HIGH FIRE DANGER.

18Z GFS SPEEDS CHRISTMAS SYSTEM UP A LITTLE PUTTING GA UNDER THE UPR LOW AS IT LIFTS EAST ON CHRISTMAS DAY. WHILE 1000-850MB AND 850-700MB THICKNESS CRITERION FOR SNOW WILL BE MET OVER MUCH OF NORTH GA...STEEP LOW LEVEL LAPSE RATES IN THIS PATTERN USUALLY GIVE US SOME PROBLEMS INTERPRETING THE 1000-850MB THICKNESS AND PRECIP TYPE. WILL NEED TO WATCH PROGGED SFC TEMPS VERY CAREFULLY AS THEY COULD BE IN THE UPPER 30S TO MID 40S EVEN WITH 850MB TEMPS AS LOW AS -4C AND 1000-850MB THICKNESSES OF LESS THAN 1300M. CERTAINLY COULD HAVE FLURRIES OR SNOW SHOWERS IN HIGHER ELEVATIONS BUT AREAS UNDER 1500FT WOULD LIKELY SEE LIGHT RAIN IF THIS RUN OF THE GFS VERIFIES.

ONE MORE NOTE...NWS GATEWAY HAD COMPUTER PROBLEMS EARLIER THAT WILL LIKELY RESULT IN SPARSE DATA FOR THE 00Z RUNS OF THE MODELS. THIS WILL MEAN THE DATA MAY COME IN LATE AND MAY NOT BE AS ACCURATE OR COMPLETE AS IT COULD BE. USE 00Z RUNS WITH CAUTION (IF THEY COME IN AT ALL). THE 00Z NAM FOR INSTANCE IS EXTREMELY SPOTTY IN AWIPS RIGHT NOW. ONLY FORECAST GRIDS BEYOND 66HRS ARE FULLY AVAILABLE WITH LIMITED DATA BEFORE 66HRS.
SNELSON

&&

[jkt21787]

Maybe not, Brent. Check this out from FFC (btw...I've noticed much more detailed AFD's from SNelson since the ice-storm two weeks ago where the performance from FFC was not quite up to snuff--ie, 10 hours and no AFD's, etc).

Seems the NWS Gateway computer was down, so data is incomplete, per this AFD.

Maybe all is not lost?

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
944 PM EST TUE DEC 20 2005

.UPDATE...
PREV FCST SEEMS TO BE GOING AS PLANNED. SOMEWHAT DRIER ACROSS NW 1/2 OF CWA TONIGHT THAT GUIDANCE ADVERTISED. CURRENT DEWPOINTS AT 9PM INCLUDE 10 AT HARTSFIELD (KATL) AND 7 AT CANTON (K47A). THIS COULD INDICATE WE COULD REACH RED FLAG CRITERIA WEDNESDAY AFTERNOON. WILL NOT ISSUE WATCH ATTM AS CURRENT FWF HIGHLIGHTS POSSIBLE RISK OF HIGH FIRE DANGER.

18Z GFS SPEEDS CHRISTMAS SYSTEM UP A LITTLE PUTTING GA UNDER THE UPR LOW AS IT LIFTS EAST ON CHRISTMAS DAY. WHILE 1000-850MB AND 850-700MB THICKNESS CRITERION FOR SNOW WILL BE MET OVER MUCH OF NORTH GA...STEEP LOW LEVEL LAPSE RATES IN THIS PATTERN USUALLY GIVE US SOME PROBLEMS INTERPRETING THE 1000-850MB THICKNESS AND PRECIP TYPE. WILL NEED TO WATCH PROGGED SFC TEMPS VERY CAREFULLY AS THEY COULD BE IN THE UPPER 30S TO MID 40S EVEN WITH 850MB TEMPS AS LOW AS -4C AND 1000-850MB THICKNESSES OF LESS THAN 1300M. CERTAINLY COULD HAVE FLURRIES OR SNOW SHOWERS IN HIGHER ELEVATIONS BUT AREAS UNDER 1500FT WOULD LIKELY SEE LIGHT RAIN IF THIS RUN OF THE GFS VERIFIES.

ONE MORE NOTE...NWS GATEWAY HAD COMPUTER PROBLEMS EARLIER THAT WILL LIKELY RESULT IN SPARSE DATA FOR THE 00Z RUNS OF THE MODELS. THIS WILL MEAN THE DATA MAY COME IN LATE AND MAY NOT BE AS ACCURATE OR COMPLETE AS IT COULD BE. USE 00Z RUNS WITH CAUTION (IF THEY COME IN AT ALL). THE 00Z NAM FOR INSTANCE IS EXTREMELY SPOTTY IN AWIPS RIGHT NOW. ONLY FORECAST GRIDS BEYOND 66HRS ARE FULLY AVAILABLE WITH LIMITED DATA BEFORE 66HRS.
SNELSON

&&

A pro met on another board said GFS ran with nearly all of its normal data, if not all of it. So no problems there. The NAM ran with less than half, however.

[JenyEliza]

Well...then maybe we jinxed it?

[jkt21787]

Well...then maybe we jinxed it?

Maybe so

Here is an update from NCEP...
SPECIAL NCEP DISCUSSION
CENTRAL OPERATIONS/NCEP/NWS/WASHINGTON DC
0450 UTC WED DEC 21 2005

210450Z...THE 00Z NCEP PRODUCTION CYCLE IS IN GOOD SHAPE.
IN SPITE OF A 30 MINUTE DELAY IN STARTING THE 00Z NAM...THE
NAM COMPLETED ON TIME. MAJOR PORTION OF THE 00Z MODEL CYCLE
IS COMPLETE.

THE MAIN OPERATIONAL IMPACT WAS TO THE DATA INGEST FOR THE
00Z NAM. FOR THE NAM RECEIVED ABOUT TWO THIRDS OF THE
NORMAL NUMBERS OF UPPER AIR REPORTS. ALSO REDUCED NUMBERS
OF SURFACE OBSERVATIONS OF ALL DESCRIPTION. THE 00Z GFS
STARTED WITH NORMAL DATA COUNTS IN ALL CATEGORIES.

[JenyEliza]

And then we have this.

So....what's the deal?

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
530 AM EST WED DEC 21 2005

.SHORT TERM...(TODAY THROUGH FRIDAY)
THIS PERIOD WILL BE DRY WITH A GRADUAL WARMING TREND. A COUPLE OF SHORT WAVES DROP SOUTHEAST ACROSS OUR CWA TODAY AND THURSDAY. HOWEVER...ONLY SOME HIGH CLOUDS EXPECTED WITH THESE SYSTEMS. RIDGING ALOFT SETTING UP FOR FRIDAY AND IT SHOULD BE VERY DRY AND WARMER. WITH NORTHWEST WINDS TODAY AND SOME TROUGHING ALOFT...HAVE STAYED ON THE COOL SIDE OF GUIDANCE. OTHERWISE GUIDANCE BLEND LOOKS OKAY.

.LONG TERM...(FRIDAY NIGHT THROUGH TUESDAY)
LONG TERM STILL INDICATING A WET PERIOD FOR SATURDAY NIGHT THROUGH SUNDAY NIGHT. LIGHT SNOW OR FLURRIES STILL LOOK POSSIBLE NORTH AND WEST SUNDAY NIGHT WITH WRAP AROUND. NOT MUCH CONFIDENCE IN THIS RUN DUE TO EARLIER TRANSMISSION PROBLEMS AND SOME MISSING DATA. IN GENERAL...DID NOT MAKE ANY SIGNIFICANT CHANGES TO THE EXTENDED.

[Brent]

I think the lower atmosphere will be too warm for snow, unless your at a higher elevation and even there it'd only be a few flakes mixed in. Look for a Cloudy, Dreary, Cold day on Sunday with some light rain.

[JenyEliza]

I think the lower atmosphere will be too warm for snow, unless your at a higher elevation and even there it'd only be a few flakes mixed in. Look for a Cloudy, Dreary, Cold day on Sunday with some light rain.

Oh goody.

[Brent]

FFC:

TEMPERATURES FALL QUICKLY BEHIND THE FRONT AND THERE MAY BE SOME
WRAPAROUND MOISTURE...BUT WITH THE SURFACE LOW SO MUCH FURTHER
NORTHWARD...THE CHANCES OF WINTRY PRECIPITATION ARE QUICKLY
DWINDLING. ANY MOISTURE THAT WE WOULD HAVE WOULD BE CONFINED TO THE
LOWEST COUPLE OF HUNDRED MILLIBARS...WELL BELOW THE -10C WARMEST
TEMPERATURE NEEDED TO PRODUCE DENDRITES. THUS...IF IT IS FREEZING AT
THE SURFACE...ANY PRECIPITATION WE WOULD GET WITH WRAPAROUND
MOISTURE WOULD BE MORE IN THE FORM OF FREEZING DRIZZLE...BUT EVEN
THAT IS NOT TOO LIKELY. HOWEVER...WITH UPSLOPE FACTORS COMING INTO
PLAY UNDER NORTHWEST FLOW...HAVE KEPT SNOW SHOWERS FOR THE MOUNTAINS
FOR LATE SUNDAY NIGHT AND EARLY SUNDAY MORNING...AS OROGRAPHIC
UPLIFT MAY BE ABLE TO LIFT MOISTURE TO THE -10 TO -15C DENDRITIC
SNOW GROWTH LAYER.

[JenyEliza]

FFC:

TEMPERATURES FALL QUICKLY BEHIND THE FRONT AND THERE MAY BE SOME
WRAPAROUND MOISTURE...BUT WITH THE SURFACE LOW SO MUCH FURTHER
NORTHWARD...THE CHANCES OF WINTRY PRECIPITATION ARE QUICKLY
DWINDLING. ANY MOISTURE THAT WE WOULD HAVE WOULD BE CONFINED TO THE
LOWEST COUPLE OF HUNDRED MILLIBARS...WELL BELOW THE -10C WARMEST
TEMPERATURE NEEDED TO PRODUCE DENDRITES. THUS...IF IT IS FREEZING AT
THE SURFACE...ANY PRECIPITATION WE WOULD GET WITH WRAPAROUND
MOISTURE WOULD BE MORE IN THE FORM OF FREEZING DRIZZLE...BUT EVEN
THAT IS NOT TOO LIKELY. HOWEVER...WITH UPSLOPE FACTORS COMING INTO
PLAY UNDER NORTHWEST FLOW...HAVE KEPT SNOW SHOWERS FOR THE MOUNTAINS
FOR LATE SUNDAY NIGHT AND EARLY SUNDAY MORNING...AS OROGRAPHIC
UPLIFT MAY BE ABLE TO LIFT MOISTURE TO THE -10 TO -15C DENDRITIC
SNOW GROWTH LAYER.

MERRY CHRISTMAS to you too, Brent.