Feb 12-13 Sleet/Snow/ZR Event

[BullCityWx]

WOW!!!!!!

 

The euro has become self aware and is clearly trying to please me.

[Buddy1987]

GFS and nam worlds apart at 66 GFS has no phasing occurring with the streams yet whereas nam was going ape s***

[Buddy1987]

GFS trying to phase at 75 now precip has been ongoing in the southeast and nc is getting it good but still need the GFS to phase earlier.

[CandymanColumbusGA]

To be honest, Columbus, GA and surrounding areas are going to be in a wait and see mode up until the CAD sets in... I know for sure we're going to see rain, but modeled dew points don't get much below 34ish down here. As someone alluded to earlier (can't remember who... ), we'd need to see a dry period to allow the CAD to set in then see the precip move in. Of course, this is in and around my area in East Central AL & West Central GA. The chances for ice go up drastically the more north and east you head from Columbus. However, as me & others have stated, CAD events throw us curveballs every so often, so we need to keep an eye on it.

[Cheeznado]

GFS colder but a lot more benign with precip than most of the other models. Looks suspect to me.

[Tacoma]

The euro has become self aware and is clearly trying to please me.

8 - 12 inches.....will be nice if and when we can start knowing this is the way it will pan out.   

[Brandonjva]

I thought one of the gfs biases was to phase to quickly? Strange

[SN_Lover]

GFS colder but a lot more benign with precip than most of the other models. Looks suspect to me.

Should we put any weight on the GFS? Seems like it's been all over the place with this event. 

[Buddy1987]

GFS colder but a lot more benign with precip than most of the other models. Looks suspect to me.

Agreed sir GFS has a much later phase and thus the lack of precip showing up on the 850 fields. Baby steps albeit slow

[Snow dog]

Agreed sir GFS has a much later phase and thus the lack of precip showing up on the 850 fields. Baby steps albeit slow

It's been the outliner for days for this event..no worries.

[tarheelwx]

FWIW, when I looked at the 18z NAM for GSO, it came up with 4" sn, ,58" ip, and .38" zr.  I think that would equate to about 3" of great sledding base on the ground.  With that much in the form of ip or zr, it is easy to see that these big snowfall maps are overdone.

TW

[superjames1992]

Gfs is a dud.

 

It's taking steps, though.  Verbatim, it's still a good hit of snow for the I-85 corridor and westward.

 

DISCLAIMER: Beware of the clown map, of course...  Just for fun.

 

[RaleighWx]

GFS colder but a lot more benign with precip than most of the other models. Looks suspect to me.

Could be having convective feedback issues again.

[RaleighWx]

18z NAM cobb output for RDU

 

1.55 of QPF

3.2 inches of snow

0.65 inches of sleet

0.89 inches of freezing rain.

 

Yuck.

[seasonsoflove]

Am I misreading that 12z Euro mean snow total map? It's pulling snowfall totals all the way down to Savannah (***not QUITE down to Savannah but you catch my drift)... all the models I've looked at for KDNL along I-20 are rain, rain, rain, with the temp bottoming out at 33 Tuesday morning.

 

I want to be excited about being part of the event but this model just seems way too liberal.

[Buddy1987]

I thought one of the gfs biases was to phase to quickly? Strange

The nam likes to over amplify too quickly not sure about the GFS phasing too soon. The GFS struggles with southern stream systems

[nchighcountrywx]

WOW!!!!!!

Reality:

Use caution.

Don't work up for disappointment due to misunderstanding of how the ECMWF calcs snow. Data does not support a 10:1 ratio

Brad Panovich (@wxbrad)

2/9/14, 16:46

yeah but these higher totals aren't supported by any data. EURO takes all frozen precip & makes it all snow using 10:1.

[crossthread]

wow, gfs looks colder.  zr down near the lowcountry away from the coast thru 54.  grand strand getting pummeled.

 

 

KILM Disco is starting to get really interesting...

 

Short term /Monday through Tuesday night/...

as of 3 PM Sunday...another high-impact winter weather event

appears to be brewing for the eastern Carolinas Tuesday and

Tuesday night. There are still several unresolved questions:

- how far south and east the freezing line at the surface will

end up...

- where the leading edge of above-freezing air within the warm

nose aloft (3000-7000 ft) ends up...

- when the onset of precipitation occurs Tuesday...

If you are reading this you have probably already reviewed the 12z

GFS...NAM...and European model (ecmwf). The 12z GFS has the best overall handle on

the mass fields (frontal positions, highs, lows) and is the default

model of choice for this storm. The 12z NAM appears to veer low level

winds too much Tuesday evening and overnight with too much warming

occurring within the boundary layer. The 00z and now the 12z runs

of the European model (ecmwf) are interesting in that they attempt to bring low

pressure from the Gulf up into the cold air wedge over the coastal

plain Wednesday night. While technically beyond the time frame

covered by the Monday-Tuesday night period...the European model (ecmwf) solution typically

does not occur and may be a clue the European model (ecmwf) may not have the best

handle this time.

After a relatively warm and dry day Monday (highs: 50s to near 60)

middle level moisture will increase rapidly Monday night with

overcast skies developing. Cold dry air pushed south by 1037 mb

Arctic high pressure over Iowa will drop lows into the low-middle 30s.

Isentropic lift arriving from the west-southwest along the

295-310k surfaces (a deep layer from 9000-18000 feet agl) will

increase throughout the day with gradually increasing chances of

precipitation. The 12z GFS individual ensemble members were

generally slower than the 12z deterministic GFS with the onset of

precipitation Tuesday...but 80+% of them still show widespread precipitation

developing by late afternoon. Surface temperatures should remain in

the middle 30s up until sufficient precipitation occurs to induce

evaporational cooling of the boundary layer...at which point temperatures

will dive down to freezing roughly north of a line from Florence

to Marion...Whiteville and Burgaw.

Precipitation type will be tricky Tuesday. Soundings initially support

mainly snow...however above-freezing air arriving at 850 mb across

South Carolina and along the coast will transition precipitation over to

rain or sleet depending on the depth of the cool dry air beneath

the warm nose aloft. Strengthening northeast winds beneath the

warm nose Tuesday night will ensure a steady supply of cold air to

offset latent heating incurred from sleet formation...and the

all-snow line may actually begin to sneak southward across

Bennettsville...Lumberton and Elizabethtown with snow + sleet

accumulations approaching 2 inches by late Tuesday night.

For the major population centers of Wilmington and Myrtle Beach...

you are very close to significant gradients in precipitation type

and ice/snow accumulation potential. Small changes in temperatures

could make tremendous differences in the outcome for this forecast.

&&

 

[Steven_1974]

The big ice storm back in 2002 basically destroyed my yard, fence, and car. My wife actually saw a hickory tree get pulled up by the root ball because of too much ice. I only got 1.25 of freezing rain. If you get 2"......my God.

http://www4.ncsu.edu/~nwsfo/storage/cases/20021204/

 

That's one storm I never want to re-live. I remember sitting up all night hearing pine trees snap and drop. I was waiting on one to fall on my house cause I had so many around it. There was one in the yard that had a branch fall out of it that was thee size of a regular tree. It nicked the roof and fell on the driveway. Good thing my car was up at the street.

[FallsLake]

Could be having convective feedback issues again.

Still wetter than 12z. Looks like near .75 QPF of snow and sleet for Charlotte to RDU.

http://mag.ncep.noaa.gov/NCOMAGWEB/appcontroller/data/gfs/18/gfs_namer_096_precip_p48.gif

[franklin NCwx]

It's taking steps, though. Verbatim, it's still a good hit of snow for the I-85 corridor and westward.

looks better than I thought but it has too much snow in the east. Alot of that is sleet freezing rain.

[jacobr57]

Still wetter than 12z. Looks like near .75 QPF of snow and sleet for Charlotte to RDU.

http://mag.ncep.noaa.gov/NCOMAGWEB/appcontroller/data/gfs/18/gfs_namer_096_precip_p48.gif

That's actually much better than it looked based on the track and 3 hour panels. I was expecting widespread quarter to half inch totals.

[packfan98]

Has anybody looked at the earlier gfs ensemble mean or individual members? Are they, or are they trending, more in-line with the other models?

Thanks!

[gritsnc]

That's one storm I never want to re-live. I remember sitting up all night hearing pine trees snap and drop. I was waiting on one to fall on my house cause I had so many around it. There was one in the yard that had a branch fall out of it that was thee size of a regular tree. It nicked the roof and fell on the driveway. Good thing my car was up at the street.

 

I think this is the storm where my oldest daughter was only 4 at the time and even she remembers that storm. We had no trees close enough to hit our house, but we were surrounded by woods. We couldn't sleep because of crashing noises from trees falling all night long and we were without power for almost a week. Since then, we have never been without a kerosene heater, carbon monoxide detector and gas grill.

[jacobr57]

Has anybody looked at the earlier gfs ensemble mean or individual members? Are they, or are they trending, more in-line with the other models?

Thanks!

[Jon]

Reality:

Use caution.

Don't work up for disappointment due to misunderstanding of how the ECMWF calcs snow. Data does not support a 10:1 ratio

Brad Panovich (@wxbrad)

2/9/14, 16:46

yeah but these higher totals aren't supported by any data. EURO takes all frozen precip & makes it all snow using 10:1.

While he's technically right, one should look at the big picture with that image instead of going "woohoo 8" snow for MBY!"

 

Ensembles are clearly above the operational with the amount of frozen precip, in some cases a couple of inches higher. Data supports more frozen precip than OP. That's what it comes down to. Yeah you could throw around QPF maps, but seeing support for more frozen precip than the OP is always better when you're trying to judge the impact of a particular storm.

[HKY_WX]

Here's the 18z nam for cae    

 

prec.png

that's insane.

[isohume]

18z NAM cobb output for RDU

 

1.55 of QPF

3.2 inches of snow

0.65 inches of sleet

0.89 inches of freezing rain.

 

Yuck.

 

You can't take modeled fzra at face value. Fzra is a self limiting process and it needs continuous reinforcement of cold air to keep accumulating. With the transient parent high Wed...the cold air will not be reinforced enough to offset the latent heat of freezing in the sfc layer. I took a cursory look at some consensus qpf across the Midlands and noted the timing is about 4-5 hrs with sub-freezing sfc temps leading to around 0.3-0.4 ice accum before the transition to rain occurs around 14Z or so. Still a sigfnt and damaging ice potential tho.  

[LithiaWx]

18z GFS looked like a good thump for the north Georgia area. Probably everything and the kitchen sink in terms of ptype.

[QC_Halo]

The big ice storm back in 2002 basically destroyed my yard, fence, and car. My wife actually saw a hickory tree get pulled up by the root ball because of too much ice. I only got 1.25 of freezing rain. If you get 2"......my God.http://www4.ncsu.edu/~nwsfo/storage/cases/20021204/

This was the worst I've seen...luckily I was south of it, but afterwards it looked like a war zone, pine trees snapped in half...literally. 3-6" of ice...now that's insane

http://www.nwas.org/digest/papers/1996/Vol20No3/Pg15-Pfost.pdf