Feb 12-13 Sleet/Snow/ZR Event

[SN_Lover]

Looks like Heavy snow at CLT by wednesday. Temps near 25. 

Mother nature really wants to compensate for 2 horrible winters. I hope this comes true!!

[RevDodd]

Hard for me to read, but looks like the serious freezing runs north of the Sandhills. Soundings indicated early sleet, then surface temps nudge up to cold rain....and a pretty hefty dose of it.

 

Given the generally north drift of these things, we're not holding our breath down here.

[NCsandhills]

Hard for me to read, but looks like the serious freezing runs north of the Sandhills. Soundings indicated early sleet, then surface temps nudge up to cold rain....and a pretty hefty dose of it.

 

Given the generally north drift of these things, we're not holding our breath down here.

Yep looks like we might miss this one. Right south of the edge again. I'll take an all day cold rain though.

[Suncat]

Hard for me to read, but looks like the serious freezing runs north of the Sandhills. Soundings indicated early sleet, then surface temps nudge up to cold rain....and a pretty hefty dose of it.

 

Given the generally north drift of these things, we're not holding our breath down here.

 True, but that could turn out to be a mixed blessing. Not having power is not much fun!

[SN_Lover]

Looking at the 500mb maps, the Euro has a phase and the gfs has the southern shortwave outrunning the northern shortwave. if the northern shortwave stays intact then the low will from over the great lakes. 

[NGA WINTER]

As much as I love a good winter storm, living in north Georgia, idk If I can hope this verifies. With the qpf this storm is being modeled to have, and temps around or below freezing it would be an awful situation. For Gods sake we have a topic about snow apocalypse in Atlanta and stories of people being stranded. But I do love a winter storm! By the way guys thanks for all the pbp and constant updates! Carry on!

[RaleighWx]

How does it look in Southeast Va. We are kinda in no-mans land, lol I can't tell much by the free maps. I assume the cold air errodes farily quickly (we are not a favored CAD area), but am thinking we would see some significant frozen precip on the front end?

 

Thanks

I guess it depends on where in SE Va. 1-3 inches before changeover to rain it looks like more further inland.

[Lookout]

Hickory probably gets probably 16" of snow over 2 days. Wow. 

That's sick LOL.

 

I just saw the euro and wow indeed. I am so jealous of nc right now.

 

It would be nice if that moved more south but it probably won't. You know this is a strong wedge though when CAD actually shows up at 850mb. I wonder if there would be an area of heavy sleet somewhere over ne ga or the upstate to the south of the snow line or if it goes to freezing rain.

 

edit to add. I see allan already made mention of it.

[buckeyefan1]

Now the bad news...KCUB is an inch of QPF that appears to be all ZR.

I'm not listening to any bad news       

[calculus1]

So, here is the biggest/best frame from the 12Z Euro output today taken from Wunderground.  This is for Wednesday afternoon, hour 150 on the model.

 

First the lovely snowfall map, with all the usual caveats:

 

 

 

And then the 850 mb temp map at the same time.  This does appear to be indicative of profiles that would support a majority of this precipitation falling as snowfall in the western half of NC, at least:

 

 

 

And, lastly, we have the 2m temps for the same time frame.  So, even though most of this precipitation is not snowfall in N GA and SC, the surface temps are quite cold, which leads to icy conditions:

 

 

 

****If you choose to respond to this post, please delete the images in your response, so as not to clutter up the thread unnecessarily.****

[Lookout]

 As modeled by the 12Z Euro and especially considering a tendency toward a warm bias, no because it really isn't even that close of a call imo. With the Euor's setup, it would probably get down into the high 20's for much of ATL. The 12Z GFS might be closer to your scenario even with my thinking it is a few degrees too warm is accurate.

 

Edit: Much of the ATL-AHN corridor on the 12Z Euro is within the +3 to +5 C 850 mb zone, which is right in the wheelhouse for major N GA ZR's with a wedge and heavy precip. The 12Z GFS has similar 850's.

 

Edit 2: If 850's cool a little more, we could even start looking at heavy IP possibilities...Tony are you listening?

totally agree larry. The fact that the euro is showing cad at 850mb is huge. Only the strongest wedges does it show up at that level. It means there is a deep layer of caa with our parent high and would likely spell very cold temps pretty far to the south. 

 

I'm a little behind here because I just noticed you mentioned the sleet possibilities as well. But that is the first thing I thought of when I saw the euro...that there could be an area of significant sleet accumulation. I would imagine 950mb to 900mb temps are very cold indeed if it shows up at 850mb which would tend to favor an area of sleet.

 

btw, to show you how strong this caa is. Note that sub zero 850mb temps actually make it into southeast TN and northwest ga from the northeasterly flow wed afternoon. That is pretty incredible because that doesn't happen very often.

[jburns]

Since this is obviously the primary thread I am going to relent and pin it earlier than I said. There have been only 3 posts in the pattern thread the entire day.  I'd hate to be the one coming back in 5 years to research this winter.

[Cheeznado]

As modeled by the 12Z Euro and especially considering a tendency toward a warm bias, no because it really isn't even that close of a call imo. With the Euor's setup, it would probably get down into the high 20's for much of ATL. The 12Z GFS might be closer to your scenario even with my thinking it is a few degrees too warm is accurate.

 

Edit: Much of the ATL-AHN corridor on the 12Z Euro is within the +3 to +5 C 850 mb zone, which is right in the wheelhouse for major N GA ZR's with a wedge and heavy precip. The 12Z GFS has similar 850's.

 

Edit 2: If 850's cool a little more, we could even start looking at heavy IP possibilities...Tony are you listening?

I really hope that the ice stays away from ATL, at least where I live. I have no desire to be out of power for days. But I agree this looks very ominous for somebody in N/NE Georgia

[packfan98]

NWS Raleigh AFD:

 

TUESDAY NIGHT THROUGH THURSDAY...OPERATIONAL GFS AND ECMWF DEPICTING
AN ACTIVE SOUTHERN STREAM WITH STRENGTHENING LOW LEVEL FLOW AS
CYCLOGENESIS TAKES PLACE ACROSS THE SOUTHERN GULF STATES. A STRONG
HYBRID/MILLER B DAMMING SCENARIO WILL EVOLVE...WITH WARM AIR
SPREADING PRECIP ACROSS THE COOL DOME LATER TUE NIGHT...BUT
ESPECIALLY WED AND WED NIGHT. INITIAL PRECIP COULD BE SNOW ACROSS
MUCH OF THE NORTH AND WEST AS THE COLUMN WILL BE LARGELY
SUBFREEZING...WITH RAIN ACROSS THE SOUTH. MODEL DIFFERENCES ARE
MINOR ENOUGH CONCLUDE THAT THE MILLER B SCENARIO CONTINUES TO
EVOLVE...AND WITH COLD AIR IN PLACE...A WIDE TRANSITION ZONE BETWEEN
RAIN AND SNOW IS POSSIBLE...EVEN LIKELY TO DEVELOP...ACROSS THE
PIEDMONT ON WEDNESDAY PER CLIMATOLOGY. AT THIS POINT WILL BE RAISING
POPS INTO THE LIKELY CATEGORY WITH RAIN OR SNOW AS PRIMARY WEATHER
TYPES AS DETAILS BECOME MORE CLEAR AND CONFIDENCE INCREASES IN
SUBSEQUENT MODEL RUNS. HIGHS WEDNESDAY WILL BE COOLER THAN
GUIDANCE...WITH THE NORTHWEST POSSIBLY NOT GETTING OUT OF THE MID
30S. MEANWHILE...THE SOUTHEAST COULD REACH 50. A COASTAL LOW IS
EXPECTED TO BECOME DOMINANT AND LIFT NORTH OF THE AREA WEDNESDAY
NIGHT...AND WITH THE LOSS OF THE DEEPER MOISTURE...THE NUCLEATION
ZONE COULD DE-SATURATE TO PRODUCE LIGHT FREEZING RAIN/FREEZING
DRIZZLE ACROSS THE NORTH AND WEST OVERNIGHT. LOWS WILL RANGE FROM 30
NORTHWEST TO 36 IN THE SOUTHEAST. ON THURSDAY...THERE WILL BE THE
POTENTIAL FOR LINGERING PRECIP...AND POSSIBLY SOME FREEZING
DRIZZLE...WITH HIGHER POPS NORTH AND WEST WHERE LOW LEVEL MOISTURE
WILL BE LOCKED IN PLACE BY THE NORTHERLY FLOW BEHIND THE DEPARTING
LOW. THURSDAYS HIGHS WILL BE MOSTLY IN THE 40S...REACHING THE LOW
40S LATE IN DAY (IF AT ALL) IN THE NORTHWEST.

[RevDodd]

So, here is the biggest/best frame from the 12Z Euro output today taken from Wunderground.  This is for Wednesday afternoon, hour 150 on the model.

 

 

 

 

And then the 850 mb temp map at the same time.  This does appear to be indicative of profiles that would support a majority of this precipitation falling as snowfall in the western half of NC, at least:

 

 

Dang! That 850 mb map (dutifully removed) really shows the Bunnlevel line between the Sandhills and Piedmont in NC. That's a landmark snow-no snow divider around here.

[deltadog03]

That SCREAMS ICE from just north of MCN ATL-AHN  HUGE snow and prolly some sleet for GSP and a dumpage for NC

[SnowNiner]

 The 12Z Euro is a serious ZR all of the way to the ATL-AHN corridor verbatim via a Miller B per the model's two meter temp.'s. This is the coldest run of either the Euro or the GFS by a good margin (although the 12Z GFS is fairly close) for that corridor and the qpf is 1.5-2"! IF this were to verify closely as a ZR, it would potentially be the worst there since 1/1973. Combine that with the 12Z GFS doing something similar qpfwise (but with a Miller A, not Miller B ) and considering colder recent model trends, the risk of a major winter storm in N GA ~2/12 is clearly increasing though still only slowly due to inherent uncertainty six days away. Also, prior to 12Z today, the models were too warm for N GA (at least verbatim).

 

Edit: Also, keep in mind that the Euro, if anything, is warm biased at two meters when there is a wedge and steady precip. in the SE.

 

Funny, it doesn't look like a Miller B to me.  I only see the low in the gulf at 144, then it take it up the coast.  However I'm only looking at the e-wall maps.  A B would explain alot of the mixed precip though rather than the standard rain/snow line. 

 

I also don't see a low in the lakes; it's more over to the mid-west.  That probably makes this run so much colder.  I'm rooting still for the Miller A, but even if it's a B we can still be in the game due to the CAD it seems.  Very interesting set up.  It almost has a hybrid A/B thing going for it.   

Great runs today.  I'd say CLT is definitely in the game for a winter storm at this point.  Here's hoping the models don't go.....YOINK!!

 

[Cheeznado]

I doubt very seriously that this will be snow for anyone in GA except maybe in the far NE to start. If it is as cold as the models are suggesting, then the one thing that could save us from a crippling ice event is some sleet. Back in the 80s (forget the year) there was a system that everyone thought would be devastating ice but we ended up with 3-5" of sleet.

[NavarreDon]

Here is the afternoon disco by GSP:
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
AS OF 340 PM EST THURSDAY...THE EXTENDED RANGE PERIODS BEGINS ON
SUNDAY EVENING WITH A DEPLETING NWFS PATTERN ACROSS THE HIGH
TERRAIN OF NC. A WEAK UPPER WAVE WILL DIVE OUT OF THE ROCKIES
MONDAY MORNING AND ENTER THE TENNESSEE VALLEY MONDAY AFTERNOON.
COLD AIR ADVECTION WILL LIKELY BE ONGOING AS CANADIAN HIGH PRESSURE
BUILDS IN ACROSS THE MIDWEST. MODEL DISCONTINUITY CONTINUES WITH
THIS FIRST WAVE AS THE ECMWF IS MUCH WETTER YET WARMER WHILE THE GFS
TRENDS DRIER YET COOLER. WENT WITH A GFS LEANING BLEND OF THE TWO
WITH POPS INCREASING TO HIGH END SLIGHT CHANCE LEVELS ACROSS MUCH OF
THE REGION. FORECAST WILL MENTION BRIEF PERIODS OF SNOWFALL ALONG
THE HIGH TERRAIN WITH PERIODS OF A WINTRY MIX POSSIBLE ELSEWHERE
INTO TUESDAY MORNING. LITTLE TO NO SNOW OR ICE ACCUMULATION IS
EXPECTED WITH THIS FIRST WAVE.

MEANWHILE THE ABOVE MENTIONED SURFACE RIDGE WILL SHIFT EASTWARD
TAKING ROOT OVER NEW ENGLAND...WHILE THE NEXT UPPER TROF DIGS
THROUGH THE CENTRAL PLAINS. A SURFACE LOW IS STILL PROGGED TO
DEVELOP OVER THE NORTHWESTERN GULF AND EVENTUALLY EJECT TO THE
NORTHEAST IN MILLER A FASHION. CAD WILL BE IN PLACE ACROSS THE
SOUTHERN APPALACHIANS BY WEDNESDAY MORNING WHEN THE BULK OF THE
MOISTURE ASSOCIATED WITH THE DEEPENING SURFACE LOW MOVES IN. MODELS
HAVE COME INTO BETTER AGREEMENT WITH REGARDS TO THE OVERALL TRACK OF
THE SURFACE LOW AND THE DEPTH OF THE WEDGE. HOWEVER...THE
PERSISTENCE OF THE CAD REMAINS THE BIG QUESTION. THE ECMWF IS NOW
COOLER WITH SUBFREEZING LEVEL WET BULB TEMPERATURES PREVAILING AS
FAR SOUTH AS THE MIDLANDS...LASTING THROUGH MUCH OF THE
PRECIPITATION EVENT. THE GFS ON THE OTHER HAND HAS SHIFTED COURSE
FROM THIS TIME YESTERDAY WITH THERMAL PROFILES BEING
WARMER...EARLIER...AS THE CAD RETREATS. WITH THAT SAID...WILL KEEP
POPS BELOW LIKELY LEVELS AT THIS POINT DUE TO UNCERTAINTY OF
PRECIPITATION AXIS PLACEMENT. AS FOR PTYPE...FORECAST WILL
HIGHLIGHT MENTION OF MAINLY SNOW NORTH OF THE I40 CORRIDOR WITH A
WINTRY MIX SOUTHWARD INTO THE NC/SC PIEDMONT. SOME ACCUMULATING ICE
AND SNOW LOOKS POSSIBLE...HOWEVER AT THIS POINT...AMOUNTS AND
LOCATIONS ARE TOO UNCERTAIN. WILL CONTINUE TO MONITOR THIS SYSTEM
IN THE COMING DAYS FOR POTENTIAL WINTER WEATHER HAZARDS.

[EmersonGA]

I doubt very seriously that this will be snow for anyone in GA except maybe in the far NE to start. If it is as cold as the models are suggesting, then the one thing that could save us from a crippling ice event is some sleet. Back in the 80s (forget the year) there was a system that everyone thought would be devastating ice but we ended up with 3-5" of sleet.

Totally agree.  Even the superCADs that go all the way to Alabama such as 01/2005 and 01/2000 didn't produce much if any snow.  I think we had a dusting of snow/sleet in 2000 before it went all to freezing rain.  January 2005 started as rain in the upper 20s and switched to sleet in the low 30s as the storm wore on thankfully.  That one would have been nasty otherwise.

[burgertime]

12z GFS ENS has the majority of it's members with snow in NC. One is even a monster run for WNC but that's to be expected. Temper excitement. We saw what happened last week. I am optimistic about this but anytime there is phasing it gets dicey. Hopefully models have a good handle on this one. 

[Solak]

Interesting that GSP is calling for a Miller A type situation, while RAH refers to the setup as a Miller B.

[NEGa]

ok its been showing up long enough to get my attention lol.  IIRC from the last one (05) this is looking more and more like the set up and progression of model runs that shows a pretty good signal for a strong cad event, including into n ga.  if these trends continue with the hp and wedging a lot of us may be in line for a pretty big winter storm, esp if there is a juicy low moving out of the gulf (and our moisture isnt "robbed" by convection on the coast).

 

for those in ga hoping for trends to snow, while it could start as a thump of snow, most of these type events (as lookout, gawx and others stated) are freezing rain (or sleet if the cold air is deep enough). virtually all of this type set up i recall ended as freezing rain or even rain depending on how fast the wedge is scoured out.  i think we have had ice trend to show snow to ice, but i personally cannot remember this set up going to all snow in n ga (although not saying it couldnt happen). 

 

the last couple of years we have had a lot of very wet systems moving through the se but were missing the hold high pressure which we have seen a lot of this year.  i dont mind ice but do hope if that is the case we at least get some sleet to temper the ice accretion.  if we are finally seeing things come together with the cold enough cad to get in the upper 20s and a GOM storm it could be a doozy. 

[Tony Sisk]

Interesting that GSP is calling for a Miller A type situation, while RAH refers to the setup as a Miller B.

 

Historically, Miller B events do not produce snow for GSP area. The mountains have tremendous effect on a Miller B.

I could be wrong, but aren't most the models showing this in line with a Miller A?  Could be that RAH had a typo.

In typical fashion....GSP is extremely conservative this far in advance.

[Shawn]

Historically, Miller B events do not produce snow for GSP area. The mountains have tremendous effect on a Miller B.

I could be wrong, but aren't most the models showing this in line with a Miller A?  Could be that RAH had a typo.

In typical fashion....GSP is extremely conservative this far in advance.

 

KCAE is too.. but we have this from them already:

THE MODELS SHOW A WEDGE-RIDGE PATTERN WEDNESDAY INTO THURSDAY...WITH  A DEVELOPING SIGNIFICANT UPPER-LEVEL TROUGH AND ASSOCIATED LOW  PRESSURE SYSTEM MOVING ALONG THE GULF COAST AND THEN ACROSS THE  WESTERN ATLANTIC. THE MODELS HAVE NOT BEEN CONSISTENT WITH THE  TIMING OF THIS SYSTEM. THERE IS A POSSIBILITY OF ENOUGH COLD AIR  ASSOCIATED WITH THE WEDGE PATTERN FOR A MIXTURE OF RAIN/SLEET...MAINLY  IN THE NORTH PART FROM LATE TUESDAY NIGHT INTO WEDNESDAY  MORNING...AND ALSO THURSDAY MORNING.  

[Poimen]

Interesting that GSP is calling for a Miller A type situation, while RAH refers to the setup as a Miller B.

 

I think with the CAD signature, if the primary low goes farther north, we will end up with a Miller B.

[GaWx]

 

That's interesting, Larry. I didn't know that location made that much of a difference. Thanks for sharing that. Do you know the geographical extent of those ice storms? I wouldn't think that an ice storm with a Miller A is not doable, but it seems like the geographical coverage of it would be much less than any rain or snow coverage associated with it or with a a Miller B-type system.

 

Cold Rain, 

 I just did some additional research of CLT/RDU/GSP/GSO NWS data for Miller A's that produced major ZR or IP at ATL:

 

1. 2/17-18/1979: was a 4" IP at ATL that I later added (you may not have seen) that has been since referred to as "PD #1".

 

a. CLT: mostly snow but some IP the last few hours. 10" of S/IP from 1.30" liquid. 

b. RDU: almost all snow. 10.4" from 1.19" liquid. A little IP/ZR near the end.

c. GSP 8.2" of almost all snow from 0.8" liquid (some IP mixed in)

 

 

2. 2/6-7/1979: a major ATL ZR;  

 a. CLT: After ~4-5" of snow, there was a major combo of IP and then ZR with ~1" total liquid equivalent for just the IP/ZR! Total storm liquid equiv. was 1.43"!

 b.  After ~5" of snow, there was ~0.31" liquid equiv. of IP and then ZR. total storm liq. equiv. was 0.86".

 

 

3. 1/7-8/1973: one of worst ZR's ever at ATL.

a. CLT: 0.87" liquid; snow changed to IP; about a 50-50 mix liquid equiv. wise ; total S/IP 5.5"

b. RDU: 0.85" liquid; mainly snow (6.4")

 

 

4. 3/25/1971: major ATL ZR (latest in season on record)

 GSP, CLT, RDU: all had 5-7" of S/IP from 0.80" to 1.1" liquid. All three changed to IP and then ZR. The % of liquid that was IP/ZR was ~40-50%.

 

 

5. 12/25/1943: major ATL ZR

a. CLT: major ZR ~1" liquid

b. GSO: 0.5"+ liquid of IP/ZR combo

 

 

6. 1/7/1940: major ATL ZR

a. GSO: moderate IP (mainly) with 0.4" accum./ from 0.28" liquid

b. CLT: moderate IP/ZR with 0.9" accum. from 0.57" liquid

c. RDU: IP and likely ZR, too, with T of accum. from 0.83". Must have been mainly ZR since only a T of accum.'s of IP and temp.'s 32 or lower

 

 

7. 12/16/1932: major ZR ATL

 CLT: S/IP/ZR combo 1.30" liquid produced 3.8" S/IP. So, there was clearly a sig. portion that was IP/ZR.

 

 

8. 1/21/1918: major ATL ZR

 I don't have detailed info for any NC/SC cities. However, the weather map suggests that most NC cities may very well have had mainly snow. I'll just assume that for now.

---------------------------------------------------

 

Summary/Conclusion:

 

 All but storms #1 and #8 clearly had a significant to major IP/ZR component into parts of SC/NC. So, the geographical extent of sig. to major IP/ZR was pretty extensive for 6 of the 8 Miller A's being analyzed.

[superjames1992]

Someone on the Mid-Atlantic subforum said the Euro ensembles were colder/farther east than the op. Does anyone have them?

[SN_Lover]

I think with the CAD signature, if the primary low goes farther north, we will end up with a Miller B.

According to the ensembles of the GFS the miller B transfer happens off the coast of New England. 

[burgertime]

I think with the CAD signature, if the primary low goes farther north, we will end up with a Miller B.

 

I'm not trying to be mean and maybe you meant this as a joke but this just made me laugh because of how totally obvious the statement is.