White Christmas in the Deep South???

Valkhorn · #1 Postby **Valkhorn** » Wed Dec 17, 2003 1:41 pm

OK The 12z GFS is attaching itself to the 00z and 06z runs. The previous runs had a nice cold air pocket developing behind the Christmas storm and with wrap-around moisture developed a nice chance of snow showers in the deep south.

Only now the 12z GFS is getting really strange with an extended chance of snow snowers across the deep south:

Seems strange I know, and I know it could be -removed-, but I sure would love for this to verify.

#2 Postby **gboudx** » Wed Dec 17, 2003 1:51 pm

What do these maps mean? I see that they are 850mb temp and precipitation maps. First, are the temps in C or F? Second, does 850mb refer to ground-level? Just curious since I have no idea on how to read these maps.
Thank!

GalvestonDuck · #3 Postby **GalvestonDuck** » Wed Dec 17, 2003 2:01 pm

I'm guessing Celsius not Fahrenheit. For example, on the third map, there's a 0 degree area that expands from the midwest to LA through the deep south and up to the OH valley. I'm willing to believe temps in the 30's F, but not 0.

#4 Postby **vbhoutex** » Wed Dec 17, 2003 2:07 pm

Basically and simply what you are seeing is freezing temps(the 0ºC line very near the surface with precipitation wrapping back into those temps which would produce frozen precipitation of some sort. This is a simple answer and I'm sure some of our pros can be more detailed. I can't remember exactly what level 850mb is at, but it is near the surface(my handy dandy chart is at home by my comp). :roll:

Lindaloo · #5 Postby **Lindaloo** » Wed Dec 17, 2003 2:08 pm

We have been in the 0's once GD. LOL!! Oh please, send us some snow.

#6 Postby **bfez1** » Wed Dec 17, 2003 2:18 pm

Lindaloo wrote:We have been in the 0's once GD. LOL!! Oh please, send us some snow.

I second that, Linda

#7 Postby **gboudx** » Wed Dec 17, 2003 2:19 pm

I found some info on 850mb. Apparently it's approximately 1,500 feet above the surface. It supposed to provide a good idea of surface temps. Would be nice if those maps held true. I don't care for ice or sleet on Xmas day(have to travel), but being cold out would be nice. Thanks for the answers.

Valkhorn · #8 Postby **Valkhorn** » Wed Dec 17, 2003 2:21 pm

Exactly, either way if this verified I'd love it

But yes, its the GFS, so who knows...

GalvestonDuck · #9 Postby **GalvestonDuck** » Wed Dec 17, 2003 2:22 pm

Lindaloo wrote:We have been in the 0's once GD. LOL!! Oh please, send us some snow.

Like I said, 'twas a guess.

Never been in the 0's here, as far as I can tell. Two years ago in March, it got below 32, which they said was a record -- that it rarely gets below freezing temp here on the island.

BRrrrrrrrrrrrrrrr!

Lindaloo · #10 Postby **Lindaloo** » Wed Dec 17, 2003 3:44 pm

Hey, I remember one Christmas Eve back in the 80's we had some sleet. I loved it.

therock1811 · #11 Postby **therock1811** » Wed Dec 17, 2003 3:56 pm

Yikes...that 0°C line is really far south per the 12z...something I don't know I've ever seen...

Valkhorn · #12 Postby **Valkhorn** » Wed Dec 17, 2003 4:20 pm

The 0C line has been muuuuuch further south than that before

This is the GFS we're talking about

Stormsfury · #13 Postby **Stormsfury** » Wed Dec 17, 2003 9:16 pm

gboudx wrote:I found some info on 850mb. Apparently it's approximately 1,500 feet above the surface. It supposed to provide a good idea of surface temps. Would be nice if those maps held true. I don't care for ice or sleet on Xmas day(have to travel), but being cold out would be nice. Thanks for the answers.

Actually, 850mb is roughly about 4,400 ft ...

Upslope · #14 Postby **Upslope** » Wed Dec 17, 2003 9:29 pm

Galvestonduck,
I notice you are posting Lexington, KY snowfall. What is your connection?

breeze · #15 Postby **breeze** » Wed Dec 17, 2003 9:51 pm

I'm betting rain for southern mid-TN....*sigh...

#16 Postby **wx247** » Wed Dec 17, 2003 10:00 pm

breeze wrote:I'm betting rain for southern mid-TN....*sigh...

You never know Annette.

#17 Postby **RNS** » Wed Dec 17, 2003 10:03 pm

Valkhorn wrote:The 0C line has been muuuuuch further south than that before

This is the GFS we're talking about

Don/t center so much attention around the 0C isotherm at H85...it can give one a rough idea as to where the rain (or Sleet/ZRA)/snow line is located...however proper analysis of atmospheric soundings is needed to be sure that the vertical column is cold enough (or will become cold enough after the onset of precipitation...through evaporative cooling processes...for this you would want to look at the wetbulb temperature...which is what the actual temperature can fall to after precipitation begins and the environment becomes saturated) to allow for snow to be the favored precipitation type.

for example...The H85 temperature can be below freezing...however if there are warmer layers above it...the precipitation will fall in the from of sleet...making the H85 0C isotherm unrepresentative of the actual rain/ice/snow Demarcation line.

Stormsfury · #18 Postby **Stormsfury** » Wed Dec 17, 2003 10:32 pm

To add to what RNS is talking about here ...

you need other tools that the models have and that are thickness values -

1000mb-500mb Thicknesses
850mb-700mb Thicknesses (used with higher elevation locations)
1000mb-850mb Thicknesses

I answered a question on this thread about the thickness scheme parameters a few nights ago for WEATHERGURU ...

There's the link below...
http://www.storm2k.org/phpbb2/viewtopic.php?t=21122

Lindaloo · #19 Postby **Lindaloo** » Wed Dec 17, 2003 11:21 pm

Upslope wrote:Galvestonduck,
I notice you are posting Lexington, KY snowfall. What is your connection?

GalvDuck is traveling to Lexington, KY for the Christmas holidays.

Valkhorn · #20 Postby **Valkhorn** » Thu Dec 18, 2003 12:45 am

Well of course you need some value of the heights above it and temperatures at various heights.

However if you have somewhere in the 0C line or lower you stand a good chance

White Christmas in the Deep South???

White Christmas in the Deep South???

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