Strong cold air damming event in the Southeast next weekend.

[rsvh2000]

Thanks Jeny -

That was a simple one. I know what Cold Air Damming is, but just never put that CAD is what that stands for. Thanks for your invitation to join in, b ut I am a lurker by nature I am learning A LOT from all you guys !

RSVH

[Stormsfury]

06z NAM (formerly the ETA) gives (at face value) the northern half of Georgia literally about a 12 hour period of FRZ RAIN, with moderate accum. which would warrant warning criteria ...

The GFS is also locking down the damming high until the model truncates at 90 hours and jumps it offshore ... but for the GFS to pick up on such an event so far out is remarkable in itself, but remember, the GFS scours out wedges and brings coastal troughs inland too quickly in these situations.

SF

[Anonymous]

Does look like we'll see at least OVC and cold conditions in eastern SC FRI/SAT with highs low 40's FRI and lows near 33 SAT morning, along with some POP chances FRI night into SAT. SAT highs might not make it out of the upper 30's as the wedge should hold at least through that time. 12zECMWF has the 0C line very close to CHS both days, with the high center (1041mb) over NY by early SAT. So at the very least we're looking at a cold rainy event both days in eastern sections of the Carolinas. The western Carolinas (west of Columbia) and areas north of there could get very interesting during this timeframe. Of course it will all depend on how much moisture (QPF) comes into play.

[QCWx]

PRESS HGT(MSL) TEMP DEW PT WND DIR WND SPD
HPA M C C DEG M/S
E = Estimated Surface Height

970. 398.E -.5 -3.7 247.9 .6
950. 647. -1.3 -4.1 206.1 1.1
925. 860. -.1 -.9 205.8 5.7
900. 1080. 1.4 1.1 212.2 11.7
875. 1308. 1.1 .9 215.6 12.5
850. 1541. .8 .6 220.7 13.2
825. 1781. .3 .1 230.3 16.4
800. 2028. .0 -.2 244.4 18.4
775. 2282. -.6 -.8 255.3 17.4
750. 2544. -1.7 -1.9 258.5 14.3
725. 2814. -2.8 -2.9 256.3 12.5
700. 3092. -4.1 -4.3 253.6 12.0
650. 3674. -7.2 -7.8 254.3 11.4
600. 4294. -10.5 -11.6 260.0 13.3
550. 4959. -14.7 -16.6 261.8 14.4
500. 5675. -19.7 -22.0 266.7 15.8
450. 6449. -25.4 -28.2 274.0 18.0
400. 7292. -32.5 -35.7 275.2 20.3
350. 8218. -40.9 -44.6 271.9 19.8
300. 9246. -49.2 -53.3 275.2 23.0
250. 10426. -54.0 -62.9 289.2 29.6
200. 11854. -54.9 -68.0 288.0 32.9
150. 13689. -56.2 -76.4 287.4 33.8
100. 16254. -57.6 -87.0 288.6 24.8
50. 20596. -59.4 -92.6 274.0 9.3

Hopefully we can get that warm nose to be a bit thinner to give this more of a sleety look than a zr look.

[QCWx]

Looks good through 84 hours, right? Then it truncates

[Stormsfury]

BOTH the NAM/GFS are continuing to trend colder and colder with 850mb temperatures (and likely with 2 M temperatures as well) ... for CLT/HKY/GSP/ATL, everything still on track, with potential for more IP/SN in HKY, and more IP in CLT before ZR...

Still both are too aggressive along the Carolina coast with 850mb warming, (in which the 0z EC does NOT agree with), b/c the continual BS of bringing a coastal trough inland (last week, it was correct, but the CAD wasn't strong here, either) .... but this time, this is a strong cold air damming high ... it won't scour out.

Moisture has trended a bit less. A check of the model run diagnostics and such, indicate that the 12z runs have good coverage of the US/CANADA and MEXICAN RAOBS ... so as it stands, at least data coverage appears decent ... 12z ECMWF will be interesting (especially WRT to the SW low) ... which now appears MIGHT be correct ... all the models are starting to trend towards a SW cutoff low ...

QC, you're still in the game ...

SF

[QCWx]

BOTH the NAM/GFS are continuing to trend colder and colder with 850mb temperatures (and likely with 2 M temperatures as well) ... for CLT/HKY/GSP/ATL, everything still on track, with potential for more IP/SN in HKY, and more IP in CLT before ZR...

Still both are too aggressive along the Carolina coast with 850mb warming, (in which the 0z EC does NOT agree with), b/c the continual BS of bringing a coastal trough inland (last week, it was correct, but the CAD wasn't strong here, either) .... but this time, this is a strong cold air damming high ... it won't scour out.

Moisture has trended a bit less. A check of the model run diagnostics and such, indicate that the 12z runs have good coverage of the US/CANADA and MEXICAN RAOBS ... so as it stands, at least data coverage appears decent ... 12z ECMWF will be interesting (especially WRT to the SW low) ... which now appears MIGHT be correct ... all the models are starting to trend towards a SW cutoff low ...

QC, you're still in the game ...

SF

Yep, very much so. One thing that worries me is the handling of the high by the GFS. I am assuming the precip gets in here earlier than the NAM because the GFS is making the high too weak too soon, which is a bias for the GFS in CAD situations.

However, if the GFS idea is correct, then we have the potential for a decent sized storm here this weekend.

[Stormsfury]

not a lot of time to work with this tonight. Updated to a first guess posted on my site.

http://www.stormsfury1.com

(Forecast/Prognostic Discussion)

[QCWx]

I havent got the time to post all of the maps so I'll just post the CLT meteogram. The major changes here is much more snow at the beginning of this storm, plus sleet to begin the 2nd storm.

[QCWx]

Let me just get this out of the way. The GFS is trending toward a major, if not historic ice storm for the NE GA area. The latest 00z meteogram for KATL gives that area 22m of ZR QPF which is almost an entire inch.



Tomorrow will be interesting to see if the NAM trends toward the GFS or if the reverse happens. IF, IF, IF the nam trends toward the GFS this will be a tremendous ice storm for the Atlanta area.

[JenyEliza]

The official "grocery run" bulletins have been issued in Atlanta. The stores should be packed by tonight. <sigh>

Local mets are now saying "signficant ice storm". <bigger sigh>

We're all set except for bread and milk, and to re-fill our propane tank for the gas grill. Looks like I know what I'll be doing tonight. Getting ready and saying prayers that our house will be spared this time. We've got an alternate heat source and cooking, so....I guess whatever will be, will be.

Not looking forward to ice. Especially not "significant" or "historic" ice storm.

Why can't this just be snow?

[Stormsfury]

The official "grocery run" bulletins have been issued in Atlanta. The stores should be packed by tonight. <sigh>

Local mets are now saying "signficant ice storm". <bigger sigh>

We're all set except for bread and milk, and to re-fill our propane tank for the gas grill. Looks like I know what I'll be doing tonight. Getting ready and saying prayers that our house will be spared this time. We've got an alternate heat source and cooking, so....I guess whatever will be, will be.

Not looking forward to ice. Especially not "significant" or "historic" ice storm.

Why can't this just be snow?

Sorry, Jeny ... like to tell you otherwise, but thermal profiles don't support the onset of snow this time, since the temperatures between 2,000 and 5,000 ft ABV the SFC are warmer than the 2 M (SFC) temperatures ... (nature of CAD/wedging) - since the moisture comes in during the height (peak) of the CAD, ATL really has some problems ahead ...

SF

[JenyEliza]

The official "grocery run" bulletins have been issued in Atlanta. The stores should be packed by tonight. <sigh>

Local mets are now saying "signficant ice storm". <bigger sigh>

We're all set except for bread and milk, and to re-fill our propane tank for the gas grill. Looks like I know what I'll be doing tonight. Getting ready and saying prayers that our house will be spared this time. We've got an alternate heat source and cooking, so....I guess whatever will be, will be.

Not looking forward to ice. Especially not "significant" or "historic" ice storm.

Why can't this just be snow?

Sorry, Jeny ... like to tell you otherwise, but thermal profiles don't support the onset of snow this time, since the temperatures between 2,000 and 5,000 ft ABV the SFC are warmer than the 2 M (SFC) temperatures ... (nature of CAD/wedging) - since the moisture comes in during the height (peak) of the CAD, ATL really has some problems ahead ...

SF

I know....if you could give us snow, you would. And..yes, even our locals are now saying "big problems". So...we'll be preparing accordingly. So not fun to have ice. Not fun at all.

I'll be on S2k as long as we have power...but if you don't hear from me over Friday/Saturday/Sunday....you'll know why.

Please keep us updated on what you see, Stormsfury. You called it first, ya know!

Gotta scoot to work now...I'll be peeking in from work during the day.

Jeny

[Stormsfury]

Sure thing, Jeny ... I'm still not feeling too good today, either ... was diagnosed with a sinus infection, pluresy (inflammation of the rib cage), and lot of fluid in the lungs (bronchitis on the sheet) ...

I'll try to have an update today as things warrant, provided I feel well enough to do so ..

SF

[Brent]

The official "grocery run" bulletins have been issued in Atlanta. The stores should be packed by tonight. <sigh>

Local mets are now saying "signficant ice storm". <bigger sigh>

We're all set except for bread and milk, and to re-fill our propane tank for the gas grill. Looks like I know what I'll be doing tonight. Getting ready and saying prayers that our house will be spared this time. We've got an alternate heat source and cooking, so....I guess whatever will be, will be.

Not looking forward to ice. Especially not "significant" or "historic" ice storm.

Why can't this just be snow?

I know it... but Atlanta's overdue. It's been what, 5 years since the last ice storm? I wish you the best... without giving too much away, could you tell me what part of the metro you live in?

[JenyEliza]

The official "grocery run" bulletins have been issued in Atlanta. The stores should be packed by tonight. <sigh>

Local mets are now saying "signficant ice storm". <bigger sigh>

We're all set except for bread and milk, and to re-fill our propane tank for the gas grill. Looks like I know what I'll be doing tonight. Getting ready and saying prayers that our house will be spared this time. We've got an alternate heat source and cooking, so....I guess whatever will be, will be.

Not looking forward to ice. Especially not "significant" or "historic" ice storm.

Why can't this just be snow?

I know it... but Atlanta's overdue. It's been what, 5 years since the last ice storm? I wish you the best... without giving too much away, could you tell me what part of the metro you live in?

I'm in the I-75 corridor, north of Atlanta.

[JenyEliza]

Sure thing, Jeny ... I'm still not feeling too good today, either ... was diagnosed with a sinus infection, pluresy (inflammation of the rib cage), and lot of fluid in the lungs (bronchitis on the sheet) ...

I'll try to have an update today as things warrant, provided I feel well enough to do so ..

SF

ICK. Been there, done that...had Pleurisy and Pneumonia at the same time. Makes you very very sick.

If you're up to updates, good. If not, no sweat. You take care of yourself. We've got plenty of good folks keeping an eye on things in Atlanta.

Take care and feel better,

Jeny

[DLI2k5]

I heard a met on one of Atlanta's radio stations, think it's 750 AM say he thinks the precip. will start out as snow in Atl. and changeover to sleet/freezing rain. He's uncertain as well as others, but that's the scenario he seems to be favoring.

[DLI2k5]

I just saw one of the Pro's on another website say, that the 12zMM5 has a developiong low off of the SC coastline, i think around the CHS area. If i understood him correctly, he thinks this will enhance the precip. obviously and with an enhanced CAD in place, this could result in more of a snow setup for the Carolinas. SF or anyone could i get your take on this.

[GAStorm]

I heard a met on one of Atlanta's radio stations, think it's 750 AM say he thinks the precip. will start out as snow in Atl. and changeover to sleet/freezing rain. He's uncertain as well as others, but that's the scenario he seems to be favoring.

I think you heard Kirk Mellish. Here is his forecast from wsbradio.com:

WSB Meteorologist Kirk Mellish's Exclusive 5-day Forecast
TODAY...MOSTLY TO PARTLY SUNNY BREEZY HIGHS 51 LOWS 28

FRIDAY...INCREASING CLOUDINESS WINDY AND COLD 50% CHANCE OF A WINTRY MIX AT NIGHT HIGH 40 LOW 29

SATURDAY...A 70% CHANCE OF LIGHT SLEET AND RAIN, SOME RAIN MAY FREEZE ON OBJECTS ABOVE THE PAVEMENT ESPECIALLY NORTHEAST OF DOWNTOWN WINDY AND COLD WITH FOG HIGH 33 LOW 33