Icing event... 12/15-12/16

[Cameron K.]

I agree ice isn't fun unless it's at gaylord .  Even today the power lines were a bit heavy.

[JayCee]

From what I've been reading in NWS discussions, this event appears to be leaning more toward just plain rain for most of Tennessee.  The areas that have the best chance for any frozen precip is far north and northwest Tennessee.  Of course, if the artic front has a bit of a nudge in a southern direction, more of us could get in on the action. 
However, it would appear those who stay south of the front will see the blowtorch return with above normal temps.  The only good thing is moisture will also be on the increase so, perhaps, we can continue to eliminate drought conditions across our area.

[Eric]

The freshest run of the GFS is running now, but the most recent shows the 2m freezing temp encroaching on the Tennessee River and the 850 temps remaining above freezing back to AR.  AFter looking at some of the upper air modeling, I can't see anything that would keep the cold air from progressing eastward...





Above is the 96 hour run of the 12Z GFS.  It shows an inflow of moisture from the gulf rotating around the high pressure WAY up around Nova Scotia.  Clearly a 1030mb high pressure is strong...but is it strong enough to keep the cold front from progressing eastward when the entire atmospheric flow is zonal in nature.  Just thinking out loud and I'd love to hear someone else's thoughts.

[Eric]

Is it me, or does the 60 hour GFS have a severe look to it?   

[JayCee]

It appears that is going to be a very strong gradient in the temperature profile--from below normal temps just to our north to above normal temps to our south.  As usual we seem to be caught in the middle.  It will make for an interesting forecast for our area indeed. 

[Eric]

18Z is out.  At 90 hours, it shows the surface freezing line further southeast from previous runs...but not by much...maybe 50 miles or so, while the 850 temps stay above freezing till you hit AR.  Definitely going to be we'll have to watch...

[Cameron K.]

I think it's likely the high pressure may slow down the progression of the low, we'll just have see to if the front has time to catch up with the system not too mention if it'll be "potent" enough.. Looks iffy to me still, but we may see something out of that. If anything areas west of I-65 would be at greatest risk for ice. Right?

[Eric]

I think it's likely the high pressure may slow down the progression of the low, we'll just have see to if the front has time to catch up with the system not too mention if it'll be "potent" enough.. Looks iffy to me still, but we may see something out of that. If anything areas west of I-65 would be at greatest risk for ice. Right?

As it stands currently, according to the GFS (I haven't had a chance to look at anything else), areas from a line from say Clarksville, down to Waverly, towards Jackson and Memphis have the best shot according to the current run.  It'll probably change next run.

[Thundersnow]

Memphis is sure keeping an eye on it:

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEMPHIS TN
323 PM CST FRI DEC 12 2008

.
.
.

MONDAY IS WHEN THE FORECAST BEGINS TO GET VERY MESSY. THERE WILL BE
A SHALLOW ARCTIC AIR MASS MOVING INTO THE AREA BEHIND THE FRONT. THE
FRONT WILL CONTINUE PASSING THROUGH THE CWA. TEMPERATURES WILL DROP
DRAMATICALLY BEHIND THE FRONT. PRECIPITATION IS STILL EXPECTED
BEHIND THE FRONTAL PASSAGE. EXPECT RAIN COULD POSSIBLY CHANGE OVER
TO FREEZING RAIN ACROSS PORTIONS OF THE CWA...MAINLY NORTHEAST
ARKANSAS AND THE MISSOURI BOOTHEEL...POSSIBLY EXTREME NORTHWEST
TENNESSEE. HIGHS WILL LIKELY OCCUR IN THE MORNING ACROSS MUCH OF THE
AREA WITH THE EXCEPTION OF NORTHEAST MISSISSIPPI. HIGHS WILL BE FROM
THE 40S ACROSS NE ARKANSAS TO THE 60S ACROSS NORTHEAST MS.

MONDAY NIGHT...FRONT WILL LIKELY STALL JUST TO THE SOUTH OF THE CWA.
QUESTION WILL BE HOW MUCH PRECIP WILL OCCUR BEHIND THE FRONT AND
WHAT TYPE. FREEZING RAIN OR DRIZZLE IS A POSSIBILITY FOR A BIGGER
PORTION OF THE CWA. LOWS WILL BE IN THE LOWER 30S.

TUESDAY THROUGH END OF FORECAST...FORECAST GETS REALLY COMPLICATED.
MODELS HAVE DIFFERENT SOLUTIONS FOR TUESDAY. ECMWF LIFTS FRONT BACK
TO THE NORTH WHILE THE GFS BRINGS IT A TAD NORTH AND DEVELOPS A LOW
OVER NORTHEAST MS. PRECIP TYPE COULD CONTINUE TO BE AN ISSUE IF THE
GFS IS RIGHT WHILE TEMPERATURES WOULD BE WARMER IF ECMWF IS CORRECT.

AFTER TUESDAY ITS A GUESSING GAME. BOTH INDICATE LOW PRESSURE AFTER
LOW PRESSURE DEVELOPING OVER EAST TEXAS AND MOVING NORTHEAST ALONG
FRONT. QUESTION WILL BE WHERE THE FRONT IS LOCATED. FRONT WILL
LIKELY FLUCTUATE MOVING NORTH AND BACK SOUTH. COULD MEAN A BIG
DIFFERENCE IN TEMPERATURES AND PRECIP TYPE. VERY LOW CONFIDENCE IN
FORECAST FOR TUESDAY AND BEYOND. STAY TUNED.

[StormNine]

I just got done listening to the PAH conference call.   They say confidence is increasing in the arctic front making a clean cut across west ky maybe even into tn.

Def. need to watch it. 

[Clay]

It also looks like the 2nd half of December isn't going to finish as above average as we originally thought.

[StormNine]

That too esp if we can get a good deal of that arctic air about to invade parts of the west and midwest.

[Woodvegas]

The 12/12 18Z GFS shows freezing rain in West TN Tuesday morning. I know it won't play out exactly like it shows but considering the GFS sometimes underestimates the penetration of this type of lower level cold there is a chance of an ice storm somewhere in the state. The following progged 2m temps at 6am Tuesday show temps across the state when the cold front stalls in TN with ample overrunning precip...

Dyersburg=29.1
Paris=30.4
Memphis=32.5F
Nashville=36.5
Murfreesboro=38.1
Crossville=42
Knoxville=53
Chattanooga=56

[Nashville_wx]

The NAM is its extended looks to bring the 850mb line further east. Looks to also have a strong temp gradient which will makes winds pretty gusty.

18Z GFS



NAM

[JayCee]

Arctic air is notorious for "oozing" further south than the models predict.  It is heavy, dense, and can slide easily underneath a warmer air mass, creating a mess.  However, as much as I love winter weather, this setup isn't something I would care to see again.  You can't really get a good snowfall from this--just an icy mess.  Freezing rain is usually the result.  I've noticed that Memphis says "low pressure after low pressure is to develop and move along the front."  This could easily become a dangerous scenario for someone in the mid south or Ohio Valley.  I remember a two-three day ice storm around February of 1993 or 94 in Kentucky.  The amount of damage done was staggering.  Over an inch of ice fell, and the electricity was off for days.  It was cold and miserable, and NO FUN at all. 
So, even though I love winter weather and snow as much as the next wx freak, this time I'm glad to see the models putting east Tennessee in the warmer air mass.  I live in the woods, and an ice storm would be a nightmare.