Carolina/Georgia WINTER STORM pseudo-DISASTER!?!?

[Ed Mahmoud]

New WRF has Atlanta with happy heights and 850 mb temps for snow, but looking at AccuWx PPV 2 meter temps, awfully marginal. About 3ºC, 37 or 38ºF. For ballpark 8 inches of snow if all works perfectly.


Penn State U e-Wall has a regional NAM floater over the Southeast, so for the next 20 hours or so, you can track both the surface temps and 850 mb temps over your favorite city in the Southeast.

[Cristina]

[quote="Ed Mahmoud"]New WRF has Atlanta with happy heights and 850 mb temps for snow, but looking at AccuWx PPV 2 meter temps, awfully marginal. About 3ºC, 37 or 38ºF. For ballpark 8 inches of snow if all works perfectly.

What does that mean for the counties just north of Atlanta? thanks!

[Brent]

New WRF has Atlanta with happy heights and 850 mb temps for snow, but looking at AccuWx PPV 2 meter temps, awfully marginal. About 3ºC, 37 or 38ºF. For ballpark 8 inches of snow if all works perfectly.

What does that mean for the counties just north of Atlanta? thanks!

Well, IF IF IF***** things were perfect we're talking major epic snowstorm, not seen since 1993. But things probably won't be perfect so at this time I would just say it's likely there will at least be an inch or two and leave it at that. I don't want to go overboard based on the fact it's so warm today and the ground is warm and also soaked.

[Cristina]

Well, IF IF IF***** things were perfect we're talking major epic snowstorm, not seen since 1993. But things probably won't be perfect so at this time I would just say it's likely there will at least be an inch or two and leave it at that. I don't want to go overboard based on the fact it's so warm today and the ground is warm and also soaked.[/quote]
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Thanks for your response. Is there any possibility that we could have a major snowstorm? Can you please let us know if the pattern changes and you expect things to get worst. We live on a mountain and the roads here are very treacherous, just like a rollercoaster.. I'm from FL and have never driven on ice/snow.. If there's accumulation, there's no way out of our community. Thank you so much!

[Ed Mahmoud]

Not familiar with Georgia, but I'd think getting into the foothills of the Southern Apps, elevation should be your friend, as far as snow goes.

A lot of early season/late season snows in New England are strongly elevation dependent, and places as low as one thousand feet above sea level see big time snows, while the lower elevations, even away from the coast, are just rain,


I'd imagine NWS Peachtree City would be the local experts.

Snip

FOR SUNDAY...HAVE MODIFIED LOCATION OF RAIN/SNOW MIX AND SNOW
AREAS BASED ON 1000-850MB THICKNESS. 850-700MB THICKNESS EASILY
SUPPORTIVE OF SNOW SO ONLY QUESTION ON PTYPE WILL BE LOW LEVEL
TEMPERATURES AND HOW SOON HYDROMETEORS WILL MELT AS THEY FALL INTO
1000FT WARM LAYER. MODELS CONVERGING EVEN MORE ON TRACK OF UPPER
LOW AND COLD 1000-850MB THICKNII. APPEARS THAT WC GA WILL SEE
SWITCHOVER TO RAIN/SNOW OR SNOW SOONER THAN NE GA AS UPPER LOW
TRACKS FROM MGM AT 12Z TO NEAR ALB/AMERICUS AT 18Z TO NEAR
STATESBORO AT 00Z MONDAY. HAVE EDITED GRIDS TO INDICATE THIS.
ACCUMULATIONS WILL LIKELY REMAIN MODEST DUE TO WARM AIR NEAR SFC
AND WARM GROUND...AROUND AN INCH OR LESS MAINLY ON GRASSY/EXPOSED
SFCS. HOWEVER WITH STEEP LAPSE RATES ABOVE 750MB COULD SEE INTENSE
BAND OF HEAVY SNOW SETUP IN DEFORMATION AREA JUST NW OF UPPER LOW
WITH SNOWFALL RATES 1+" PER HOUR...SIMILAR TO LITERAL SNOWFALL RATES
FROM MODELS. IF TEMPS FALL TO NEAR FREEZING IN HEAVY SNOW
BAND...COULD SEE 2-4 INCHES PILE UP QUICKLY. CANT RULE OUT EVEN
HEAVIER AMOUNTS IN EASTCENTRAL GA BETWEEN ATLANTA AND AUGUSTA AS
FORCING INCREASES. AGAIN...LIMITING FACTOR FOR HEAVY SNOW IS WARM
LAYER IN LOWEST 1000FT WHICH IS NOT HANDLED WELL BY MODEL P-TYPE
ALGORITHM WHICH FOCUS ON 1000-850MB TEMPS TOO MUCH IN CASES LIKE
THIS. WILL WATCH 12Z MODELS CLOSELY AND UPDATE FCST AS NEEDED.

SNELSON

[Cristina]

Thank you!

[Brent]

EXPECT SWATH OF SIGNIFICANT PRECIPITATION NORTH AND NORTHWEST OF
H8/H5 LOW TRACK...ALONG AND EITHER SIDE OF A LINE FROM THOM ASTON
TO MILLEDGEVILLE TO AUGUSTA. IF GFS AND NAM SNOW ACCUMULATIONS
PROGS ARE TO BE BELIEVED...COULD SEE AN INCREDIBLE AMOUNT OF
SNOW...AROUND 6 TO 12+ INCHES. LIMITING FACTORS FOR SEEING THIS
MUCH SNOW WILL BE 1000-1500FT LAYER OF ABOVE FREEZING TEMPERATURES
NEAR THE GROUND WHICH IS PROGGED TO PERSIST OVER ERN 2/3RDS OF THE
STATE THROUGH EARLY AFTERNOON AS WELL AS WARM GROUND/SOIL TEMPS.

BASED ON THE LIMITING FACTORS AND COLLABORATION WITH OFFICE AND
NEIGHBORING WFO FORECASTERS...EXPECT 1 TO 2 INCHES ACROSS ALL BUT
FAR SOUTH AND SOUTHEAST PART OF CWA. MOST LIKELY TIME FOR PRECIP
TO SWITCH TO SNOW WOULD BE BETWEEN NOON AND 9 PM SUNDAY... EARLIER
OVER WC GA AND LATER OVER ERN GA. HAVE ISSUED WINTER WEATHER
ADVISORY FOR THIS AREA.

ONE MAJOR CAUTION WITH THIS STORM IS THAT WE CANNOT RULE OUT AN
INTENSE BAND OF CONVECTIVE SNOW WITH SNOWFALL RATES OF 1+ INCH PER
HOUR ALONG THE EARLIER MENTIONED TRACK. THESE SNOWFALL RATES COULD
COOL THE COLUMN TO NEAR FREEZING RESULTING IN SIGNIFICANT SNOW
ACCUMULATIONS. MEDIA...EM AND INTERESTED USERS SHOULD MONITOR THIS
CLOSELY AND BE PREPARED IF A WINTER STORM WARNING IS ISSUED.

[Cristina]

thanks for posting the forecast, but unfortunately, I don't know the terminology... so I have no idea what it means? I live in Canton, GA, Cherokee County, which is a north suburb of Atlanta.

[RL3AO]

EXPECT SWATH OF SIGNIFICANT PRECIPITATION NORTH AND NORTHWEST OF
H8/H5 LOW TRACK...ALONG AND EITHER SIDE OF A LINE FROM THOM ASTON
TO MILLEDGEVILLE TO AUGUSTA. IF GFS AND NAM SNOW ACCUMULATIONS
PROGS ARE TO BE BELIEVED...COULD SEE AN INCREDIBLE AMOUNT OF
SNOW...AROUND 6 TO 12+ INCHES. LIMITING FACTORS FOR SEEING THIS
MUCH SNOW WILL BE 1000-1500FT LAYER OF ABOVE FREEZING TEMPERATURES
NEAR THE GROUND WHICH IS PROGGED TO PERSIST OVER ERN 2/3RDS OF THE
STATE THROUGH EARLY AFTERNOON AS WELL AS WARM GROUND/SOIL TEMPS.

Translation: Lots of precip (be it rain or snow) north of the track of the low along a line from Aston to Milledgeville to Augusta. If the models are right, there could be 6 to 12+ inches. Factors that could prevent high snow totals is an area of above freezing temps 1000 to 1500 feet above the ground (which would melt the snow before it hit the ground) and warm ground/soil temps.

BASED ON THE LIMITING FACTORS AND COLLABORATION WITH OFFICE AND
NEIGHBORING WFO FORECASTERS...EXPECT 1 TO 2 INCHES ACROSS ALL BUT
FAR SOUTH AND SOUTHEAST PART OF CWA. MOST LIKELY TIME FOR PRECIP
TO SWITCH TO SNOW WOULD BE BETWEEN NOON AND 9 PM SUNDAY... EARLIER
OVER WC GA AND LATER OVER ERN GA. HAVE ISSUED WINTER WEATHER
ADVISORY FOR THIS AREA.

Translation: Because of those factors and after talking with neighboring weather offices, the forecast is for 1 to 2 inches of snow across most of Atlanta's county warning area (pretty much anyplace within 150 miles of Atlanta). Rain/freezing rain will probably switch over to snow around noon Sunday.

ONE MAJOR CAUTION WITH THIS STORM IS THAT WE CANNOT RULE OUT AN
INTENSE BAND OF CONVECTIVE SNOW WITH SNOWFALL RATES OF 1+ INCH PER
HOUR ALONG THE EARLIER MENTIONED TRACK. THESE SNOWFALL RATES COULD
COOL THE COLUMN TO NEAR FREEZING RESULTING IN SIGNIFICANT SNOW
ACCUMULATIONS. MEDIA...EM AND INTERESTED USERS SHOULD MONITOR THIS
CLOSELY AND BE PREPARED IF A WINTER STORM WARNING IS ISSUED.

Translation: There could be a band of very heavy snow somewhere along the track of the storm that could cool the atmosphere enough to cause significant snowfall accumulations.

Theres the translation from weather geek speak to regular english, Cristina.

[jinftl]

Left out last paragraph of NWS discussion...and perhaps this is the 'silver lining' that will avoid a disaster or even a pseudo-disaster and make this even more in the category of 'winter's last hurrah'....by lunchtime on monday, a muddy and car-dirtying mess will be all that is left if the current forecast holds...in other words, snap the snow photos quickly...spring fever will be striking with a delighful vengeance later in the week

ONCE SYSTEM MOVES OUT LATE SUNDAY...WILL SEE RAPIDLY IMPROVING
CONDITIONS. TEMPS WILL START OUT BELOW FREEZING MONDAY MORNING BUT
WILL RISE QUICKLY TO THE 40S TO LOW 50S BY AFTERNOON. NO WX
IMPACTS EXPECTED THRU REST OF SHORT TERM PERIOD.

.LONG TERM /TUESDAY THROUGH SATURDAY/...
LITTLE CHANGE IN LONG TERM PERIOD EXPECTED. NW FLOW ALOFT WILL
PERSIST THROUGH THURS WITH ATTENDANT DRY CONDITIONS AND LARGE
DIURNAL RANGES. LARGE UPPER TROUGH TO MOVE TOWARD THE PLAINS
STATES ON SATURDAY BUT NO INDICATIONS FROM GFS/ECM OF WAA PRECIP
EVENT HERE THROUGH THE PERIOD. NO MAJOR CHANGES TO FCST.

Translated into forecast:

NWS Forecast for: Atlanta GA
Issued by: National Weather Service Atlanta, GA
Last Update: 6:26 pm EST Feb 28, 2009
--------------------------------------------------------------------------------
Tonight: A 40 percent chance of showers. Cloudy, with a low around 36. North wind between 10 and 15 mph, with gusts as high as 20 mph.
Sunday: Rain and snow, becoming all snow after 1pm. High near 40. North wind between 15 and 20 mph, with gusts as high as 30 mph. Chance of precipitation is 80%. New snow accumulation of 1 to 2 inches possible.
Sunday Night: A 20 percent chance of snow before 1am. Cloudy during the early evening, then gradual clearing, with a low around 26. Windy, with a northwest wind between 15 and 25 mph, with gusts as high as 35 mph.
Monday: Sunny, with a high near 46. North wind around 15 mph, with gusts as high as 25 mph.
Monday Night: Partly cloudy, with a low around 25. North wind between 5 and 10 mph.
Tuesday: Mostly sunny, with a high near 53.
Tuesday Night: Partly cloudy, with a low around 32.
Wednesday: Mostly sunny, with a high near 59.
Wednesday Night: Partly cloudy, with a low around 40.
Thursday: Mostly sunny, with a high near 66.
Thursday Night: Partly cloudy, with a low around 46.
Friday: Mostly sunny, with a high near 70.
Friday Night: Partly cloudy, with a low around 49.
Saturday: Partly sunny, with a high near 70.

BASED ON THE LIMITING FACTORS AND COLLABORATION WITH OFFICE AND
NEIGHBORING WFO FORECASTERS...EXPECT 1 TO 2 INCHES ACROSS ALL BUT
FAR SOUTH AND SOUTHEAST PART OF CWA. MOST LIKELY TIME FOR PRECIP
TO SWITCH TO SNOW WOULD BE BETWEEN NOON AND 9 PM SUNDAY... EARLIER
OVER WC GA AND LATER OVER ERN GA. HAVE ISSUED WINTER WEATHER
ADVISORY FOR THIS AREA.

Translation: Because of those factors and after talking with neighboring weather offices, the forecast is for 1 to 2 inches of snow across most of Atlanta's county warning area (pretty much anyplace within 150 miles of Atlanta). Rain/freezing rain will probably switch over to snow around noon Sunday.

ONE MAJOR CAUTION WITH THIS STORM IS THAT WE CANNOT RULE OUT AN
INTENSE BAND OF CONVECTIVE SNOW WITH SNOWFALL RATES OF 1+ INCH PER
HOUR ALONG THE EARLIER MENTIONED TRACK. THESE SNOWFALL RATES COULD
COOL THE COLUMN TO NEAR FREEZING RESULTING IN SIGNIFICANT SNOW
ACCUMULATIONS. MEDIA...EM AND INTERESTED USERS SHOULD MONITOR THIS
CLOSELY AND BE PREPARED IF A WINTER STORM WARNING IS ISSUED.

Translation: There could be a band of very heavy snow somewhere along the track of the storm that could cool the atmosphere enough to cause significant snowfall accumulations.

Theres the translation from weather geek speak to regular english, Cristina.[/quote]

[Cristina]

WOW, I'M IMPRESSED... I appreciate all your help... you guys/gals are the BEST!!!!

[Ed Mahmoud]

Upper low still diving more South than East...

[Ed Mahmoud]

new NAM starting to run, I'm like a 5 year old on Christmas Eve...

[Cristina]

Is that better or worst news for GA?????

[Ed Mahmoud]

Still looks too close to call, but a school cancel day Monday seems possible.


I'd trust the local NWS, they are the trained professionals.

[Ed Mahmoud]

ATL staring to mix with snow, still 37ºF, no accumulations anytime soon...



Radar looks nice...

[srainhoutx]

In the words of Ed, Double Post Warning...

Congrats Folks. Looks like a good snow for many folks. Just got a report from a pilot buddy that landed in Atlanta/ Report Thunder Snow with Heavy Snow and severe turbulence on final approach into Atlanta Hartsfield-Jackson Airport.

[srainhoutx]

ATL 011752Z 32015KT 1/4SM R09R/3500V4500FT +TSSN

Atlanta Traffic Cams... (click on Cameras Options)...

http://www.georgia-navigator.com/maps

[Dave]

MESOSCALE DISCUSSION 0184
NWS STORM PREDICTION CENTER NORMAN OK
1119 AM CST SUN MAR 01 2009

AREAS AFFECTED...NRN/CNTRL AL/GA/SC

CONCERNING...HEAVY SNOW

VALID 011719Z - 012115Z

SNOW WILL CONTINUE TO FALL ACROSS THE SOUTHEAST...GRADUALLY BUILDING
EWD WITH TIME. IN GENERAL LIGHT TO MODERATE RATES OF ACCUMULATION
CAN BE EXPECTED. HOWEVER...BANDS OF MODERATE TO HEAVY SNOW WITH INCH
AN HOUR RATES ARE LIKELY...AS WELL AS BRIEF CONVECTIVE BURSTS OF
SNOW...MAINLY OVER NRN/CNTRL GA. THIS WILL LEAD TO LOCALIZED AREAS
OF SIGNIFICANT ACCUMULATIONS...ESPECIALLY OVER E CNTRL/NERN GA INTO
CNTRL/WRN SC.

AN INTENSE UPPER LOW IS NOW BECOMING MORE NEGATIVELY TILTED OVER THE
SRN AL/GA BORDERS. STRONG COLD ADVECTION IN ITS WAKE HAS BROUGHT
SUBFREEZING TEMPERATURES AND SNOW INTO THE DEEP SOUTH...WITH RECENT
OBSERVATIONS IN AL IN BIRMINGHAM AND IN GA AT ATLANTA AND FT BENNING
REPORTING MDT/HVY SNOWFALL. TEMPERATURES WILL CONTINUE TO PLUMMET
INTO GA/SC AS THE UPPER LOW SHIFTS E THEN NE. STRONGEST DEFORMATION
ZONE REMAINS NORTH AND WEST OF THE UPPER LOW...REFLECTED IN RECENT
ENHANCEMENT ON WV IMAGERY OVER NRN/W CNTRL GA AND BACK INTO CNTRL
AL. PRECIPITATION HAS BEEN INTENSIFYING RECENTLY ACROSS THESE
AREAS...ESPECIALLY NEAR THE ATLANTA METRO WHERE THE UPPER LOW WILL
INITIALLY BE SLOW TO MOVE EWD...ALLOWING HEAVIER RATES TO LINGER.
DYNAMIC COOLING MAY ALLOW SOME SITES TO SWITCH TO SNOW EARLIER THAN
MODEL FORECASTS HAVE ANTICIPATED...WHILE INCREASING ISENTROPIC LIFT
WITH RELATIVE WARM/MOIST AIRMASS TO THE N AND E BEING LIFTED ATOP
SUBFREEZING TEMPERATURES TO THE S AND W WILL CONTRIBUTE TO ENHANCED
SNOWFALL RATES IN AN ALREADY SATURATED AIRMASS. AS THE LOW BEGINS TO
SHIFT EWD THEN NEWD...E CNTRL/NERN GA INTO CNTRL/WRN SC WILL BECOME
FAVORED. OCCASIONAL LIGHTNING STRIKES HAVE BEEN OBSERVED ACROSS NRN
GA...AND AN ELEVATED LAYER OF INSTABILITY WILL ALLOW THIS TREND TO
CONTINUE EWD. AS THIS OCCURS...LOCALIZED BURSTS OF HEAVIER SNOWFALL
CAN BE ANTICIPATED. DESPITE WARM GROUND/SOIL TEMPERATURES...SNOW HAS
BEEN ACCUMULATING ACROSS THE SOUTHEAST. ADDITIONALLY...SHOULD
BANDING/THUNDERSNOW OCCUR...OVERALL ACCUMULATIONS WILL BE HIGHER
THAN MODEL FORECAST WITH RATES OF AN INCH AN HOUR POSSIBLE...WHICH
HAS BEEN OBSERVED IN THE PAST TWO DAYS.

..HURLBUT.. 03/01/2009

[Ed Mahmoud]