Feb 12-13 Sleet/Snow/ZR Event

[superjames1992]

Looking at free maps it looks like 850's are cold this run.

 

You are correct and it's a great sign for those of us that want snow.

 

(WeatherBell actually isn't out far enough to see the storm quite yet, but you can tell it's going to be colder).

 

One thing to note is that the storm is about six hours or so slower coming in than at 12z.

[SN_Lover]

How so?

The southern shortwave is outrunning the northern shortwave. somehow they combined barely in this run to form the qpf gawx is talking about. i would like to see the southern shortwave slow down in future runs, not speed up like they did with the GFS and Euro. 

[HKY18]

The southern shortwave it outrunning the northern shortwave. somehow they combined barely in this run to form the qpf gawx is talking about. i would like to see the southern shortwave slow down in future runs, not speed up like they did with the GFS and Euro. 

Definitely a trend that isn't great on the OP runs, ensembles at 12z were very encouraging especially the euro, usually when every ensemble member is showing a winter storm/event it's not gonna totally bust even at 144hr out.

[Lookout]

The euro...is yummy lol

 

Snow to snow/sleet here then to sleet/freezing rain with over 1.5 liquid falling as  one or the other for north ga, the upstate up. Over one inch liquid as all snow over western north carolina. Temps below freezing for all of northeast and even east ga the entire event. Half is probably snow here as 850mb temps cool to around 0c over parts of north ga. It's a rather strange temperature evolution really....pretty unique.

 

fwiw, taken at face value. Maybe as much as 0.75 falls as snow and the other 0.75 is sleet and/or freezing rain. It's really hard to tell because the 0c 850mb isotherm dips down into far northeast ga/far western upstate..then another little dot of it around atlanta..indicating that temps at that level are essentially right at freezing over most of north ga through the period that 0.75 liquid falls.

[SN_Lover]

Definitely a trend that isn't great on the OP runs, ensembles at 12z were very encouraging especially the euro, usually when every ensemble member is showing a winter storm/event it's not gonna totally bust even at 144hr out.

 

Im just gonna pretend this is a night nightmare and wake up tomorrow and hopefully see a different solution lol 

[superjames1992]

The I-85 corridor from Charlotte to GSO and the foothills is legitimately looking at 1"+ hour rates for the entirety of the hr 138-144 period.  Holy crap.  All snow (unless there's some sneaky warm nose somewhere) with 850s of -1 to -4.  BIG DOG.

 

850s warm as the storm exits. It's probably an all-snow event based on 850s for CLT, GSO, HKY, etc., possibly ending as IP at the end.  2m temperatures are basically in the mid-20s for the duration and cool throughout the event.

 

BTW, ATL might be looking at ZR per that run.  It's close.

 

EDIT: Looks like ZR for Columbia, too.

[HKY18]

The key to this event will be the southern s/w, on the euro it's stronger/sharper, the two main things to watch moving forward to the 12z runs tomorrow is: 

 

1. The strength of the shortwave.

2. The timing of the northern and southern streams, if southern stream continues to speed up, a more gfs-like solution is more likely.

[superjames1992]

The key to this event will be the southern s/w, on the euro it's stronger/sharper, the two main things to watch moving forward to the 12z runs tomorrow is: 

 

1. The strength of the shortwave.

2. The timing of the northern and southern streams, if southern stream continues to speed up, a more gfs-like solution is more likely.

 

Correct me if I'm wrong, but the Euro is generally considered superior when dealing with southern stream systems, yes?

[HKY18]

The I-85 corridor from Charlotte to GSO and the foothills is legitimately looking at 1"+ hour rates for the entirety of the hr 138-144 period.  Holy crap.  All snow (unless there's some sneaky warm nose somewhere) with 850s of -1 to -4.  BIG DOG.

 

850s warm as the storm exits. It's probably an all-snow event based on 850s for CLT, GSO, HKY, etc., possibly ending as IP at the end.  2m temperatures are basically in the mid-20s for the duration and cool throughout the event.

 

BTW, ATL might be looking at ZR per that run.  It's close.

Yeah big event on the euro, pretty consistent since 0z last night with high qpf event. Not sure about final totals but I imagine they're pretty high on 0z run. And as far as euro being superior: I'm not really qualified to speak about that but, since I've tracked winter storms when you get unanimous  agreement between the euro op and ensemble then the chances of at least something are dramatically higher. 

[Lookout]

 Euro gives 1-1.5" of qpf of wintry precip in a wide band across GA/SC/NC. Run #6 in a row!! Also, it is colder in many spots and that may mean more IP than ZR and more S than IP in some areas. It will take some time to figure this out. Bottom line: this is another weenie dream run. Thank goodness it apears Brick is in bed!

Sure is. Absolutely huge hit for everywhere really. It even has freezing rain down to south of macon and augusta.

 

 

The I-85 corridor from Charlotte to GSO and the foothills is legitimately looking at 1"+ hour rates for the entirety of the hr 138-144 period.  Holy crap.  All snow (unless there's some sneaky warm nose somewhere) with 850s of -1 to -4.  BIG DOG.

 

850s warm as the storm exits. It's probably an all-snow event based on 850s for CLT, GSO, HKY, etc., possibly ending as IP at the end.  2m temperatures are basically in the mid-20s for the duration and cool throughout the event.

 

BTW, ATL might be looking at ZR per that run.  It's close.

 

It does have a rather odd look to the cad  as the coldest surface air actually comes in more from the east than northeast. But I've never seen an ice storm in macon and augusta during cad and not atlanta.

 

But  There is zero doubt atlanta would get freezing rain if this solution verified. In fact, they would likely see at the least some sleet/snow accumulation even as the euro destroys the warm layer for a while. The freezing line gets there anyway from what I'm seeing.

 

For those wondering, to be more specific, the euro has the freezing line from near chatsworth to near athens at 12z wed. By 18z wed, it goes from blairsville to atlanta to just below macon then back east between augusta and savannah. It wouldn't get above freezing the rest of the way

 

The board would probably shut down too as it nails the mid atlantic/dc afterwards.

[SN_Lover]

Yeah big event on the euro, pretty consistent since 0z last night with high qpf event. Not sure about final totals but I imagine they're pretty high on 0z run. And as far as euro being superior: I'm not really qualified to speak about that but, since I've tracked winter storms when you get unanimous  agreement between the euro op and ensemble then the chances of at least something are dramatically higher. 

Here is the difference between the 12z and the 0z. lack of ridging in the west sped it up, it finally slowed with the ridging in the east. we will see if this is a trend or not come 12z

 

[tonysc]

 Wow, thanks, Perry, for the compliment!   Coming from you, a highly respected guru and GA weather history expert, that means a lot.  No, I don't mind. Coming after snowjam 14, how this is handled would be very interesting to say the least!! Also, coming on the heels of snowjam 14, that would certify this winter as one of the great/most memorable ones for the area imo.

 

Edit: Aside: I just read some TalkWeather posts that were downplaying ZR in ATL if it is at 31-32. I'm not a member there, but they need to be told about Jan., 1973!! Imo, they couldn't be more misinformed. 31-32 ZR can still be quite bad on the trees and wires even if the roads aren't too bad. But supposedly 1/1973 was even bad on the roads. Much of that ZR was falling at 31-32! Perry, I assume you agree. I wasn't in ATL in 1973, but have seen the temperatures and have heard from Tony (dsaur), here, about how bad it was right at 32 in Buckhead. 1/1973 is, of course, only one example of major ZR at 31-32 at ATL that caused a big mess.

I remember that storm very well, but here in the Upstate of SC it was a huge sleet storm, well actually back and forth ZR and sleet and ending as hours of solid sleet. I remember being out of school for a solid week because of that storm, and then of course about three weeks later came one of the biggest snowstorms South Carolina and Georgia has ever seen. 

[GaWx]

This 0Z Euro has the 2/12 winter storm via a pretty classic looking Miller A that crosses the FL Panhandle and then crosses the SE GA coast/goes up the east coast. I felt that the 12Z Euro could have been interpreted either as a Miller A or as a Miller B depending on the detail of maps analyzed.

 

 For the ATL-AHN corridor with these even colder 850's (mainly +1 to +3 C) vs. the 12Z Euro, the 0Z Euro looks like much more IP (perhaps mostly) and much less ZR maybe all of the way down to the southern burbs including where Tony resides since +1 to +3 C is more in the wheelhouse of IP than ZR in this area at least (per old 850 maps)! Tony, I'm not just saying that to get you excited lol. QPF is ~1.5", a huge hit! Potential IP accumulation from this if it were to happen to be about all all IP? ~4-5", close to a repeat of PD1 of 2/1979 as well as 1/1988!

 For far NE Ga, this actually may be almost all snow now with 850's near 0C and ~1.25" of qpf. Can you say a foot of snow lol? In this case, the clown has got it right ..yeehah!

 For much of the Columbus to MCN to AGS corridor, this would appear to be a major ZR to the tune of ~1.25" worth!

  Verbatim, this run has AHN, ATL, AGS, and MCN all mainly in the 30-32 range for much of the precip. but Columbus near 35. The model is likely too warm by a good 5-7 degrees in N GA imo and by a few degrees in C GA. I'd expect temp.'s to fall into the mid 20's in areas of mainly IP in N GA, similar to 2/1979 and 1/1988. Keep in mind that the Euro has a bias of being too warm in the SE when there is steady precip. in winter with strong wedging/evap. cooling. I've seen this many times. There's practically no way KATL-KAHN would be staying in the 30-32 range. Forget it, especially with IP lol.

 

Edit: Lookout,

 When I put together this post, I hadn't seen that first one of yours. I think we're largely in agreement in general for GA.

[jacobr57]

A nice hit for NC per the GGEM:

[Snowless in Carrollton]

Lookout,

When I put together my last post, I hadn't seen this one of yours. I think we're largely in agreement in general. Check mine out and see what you think fro GA. I see almost all snow quite possible in far NE GA, much more IP and much less ZR ATL-AHN vs. the 12Z Euro, and ZR now dominating in central GA instead of plain rain.

that kind of sounds like the jan 05 storm with more ip in atl and zr further south.

[GaWx]

that kind of sounds like the jan 05 storm with more ip in atl and zr further south.

 

I got mostly ZR in 1/05 on the northside of ATL but some IP did fall.

 

I just saw the 0Z CMC. Based on 850's largely near +4 C to +5 C, a strong wedge, a 1035 very cold NE high, a pretty classic Miller A track, and ample qpf (~1.25"), it looks like much of the precip. is ZR for ATL-AHN (which actually starts late on 2/11) vs. the colder Euro's major IP (imo). So, in other words, I think that the CMC's type of precip. verbatim of plain rain is wrong.

 

Edit: 0Z Euro ens. mean is ~3 to 4 C colder at 850 through the storm for GA/SC/NC. QPF isn't as heavy but is still quite ample. Night night!

[RaleighWx]

Huge hits for NC from euro and ggem .

[Ji]

Huge hits for NC from euro and ggem .

Really nice

[burgertime]

Changes with 00z runs as expected. Folks should never ever expect 20 runs in a row of the same solution. Models will spit out different solutions. Hell probably over the weekend the models probably lose the storm. Keep an eye on the ensembles, that's the key with this storm. Majority of members from 00z GFS still have significant snowfall for WNC. I do think we're seeing extremes on both sides. The Canadian was oddly enough kind of a middle of the road between the Euro and the GFS tonight. All awesome signs. 

[burgertime]

6z GFS is much wetter but that low around the lakes area is keeping it all ZR then when the bulk of precip is coming in WAA is taking over. 

[WXinCanton]

6z GFS is much wetter but that low around the lakes area is keeping it all ZR then when the bulk of precip is coming in WAA is taking over. 

 Yep, much warmer on the 6z.  Seems like more often than not those LP's to the north in the Great lakes have really done some damage to our chances.   Considering how often it's happened that solution should not be dismissed

[msuwx]

It's been fascinating to watch basically every run of every model indicate winter precip for much of the region, but often times, the details are quite different. Just look at the extremes between the 0z and 6z GFS. 

 

Euro is indeed a big dog, and it's impressive how far south the sub-freezing SFC temps extend. Also interesting that the 0z Euro didn't really rely on any phasing at all to generate the precip it did. The previous run had some phasing and a further NW track.

 

Canadian is also a big hit, and the 6z GFS has gone to a slow and relatively warmer extreme. 

 

I run through all of the modeling in detail on my video, docked on my blog which is linked below. 

[mackerel_sky]

Yep, much warmer on the 6z. Seems like more often than not those LP's to the north in the Great lakes have really done some damage to our chances. Considering how often it's happened that solution should not be dismissed

That low has been off and on for a few runs, hopefully it stays out of the way. I think it was not there on last nights Euro.

[burgertime]

It's been fascinating to watch basically every run of every model indicate winter precip for much of the region, but often times, the details are quite different. Just look at the extremes between the 0z and 6z GFS. 

 

Euro is indeed a big dog, and it's impressive how far south the sub-freezing SFC temps extend. Also interesting that the 0z Euro didn't really rely on any phasing at all to generate the precip it did. The previous run had some phasing and a further NW track.

 

Canadian is also a big hit, and the 6z GFS has gone to a slow and relatively warmer extreme. 

 

I run through all of the modeling in detail on my video, docked on my blog which is linked below. 

 

Great video as always Matt! Thanks for taking the time to put those together. 

[FallsLake]

RAH has done very well this year with potential events. I've learned to give more weight to their words than the models. For next weeks storm they are indicating this has a real chance:

Hazardous Outlook

THIS HAZARDOUS WEATHER OUTLOOK IS FOR CENTRAL NORTH CAROLINA.

.DAY ONE...TODAY AND TONIGHT.

HAZARDOUS WEATHER IS NOT EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY.

LOW PRESSURE WILL DEVELOP OVER THE GULF OF MEXICO AND LIFT UP THE

SOUTHEAST AND MIDDLE ATLANTIC COASTS DURING THE MIDDLE OF NEXT

WEEK. PRECIPITATION ASSOCIATED WITH THE LOW PRESSURE SYSTEM WILL

OVERSPREAD CENTRAL NC LATE TUESDAY THROUGH EARLY THURSDAY...AND

SOME OF THIS PRECIPITATION WILL LIKELY INCLUDE A WINTRY MIXTURE.

RESIDENTS SHOULD MONITOR LATER FORECASTS FOR DETAILS AS

CONFIDENCE IN THE EVOLUTION OF THIS MID WEEK STORM INCREASES.

Last night's Discussion

LOWER CONFIDENCE CREEPS INTO THE FORECAST FOR MONDAY IN THE EASTWARD

ADVECTION OF PACIFIC MOISTURE COMBINING WITH GULF MOISTURE OVER

EASTERN TX AND THE MISSISSIPPI VALLEY. WEAK HIGH PRESSURE OVER THE

EASTERN SEABOARD SHOULD BE ABLE TO HOLD THIS OFF FOR MUCH OF THE DAY

ON MONDAY AND WILL FAVOR A DRIER FORECAST CONSISTENT WITH THE WPC 3Z

SFC PROG. EXPECT INCREASINGLY CLOUDY SKIES WITH HIGHS IN THE LOW TO

UPPER 40S AND LOWS MONDAY NIGHT IN THE UPPER 20S TO LOWER 30S.

PRECIPITATION CHANCES WILL INCREASE ON TUESDAY AS WHAT WAS THE

NORTHERN STREAM LOW IN THE MILLER B SCENARIO FOR LATER IN THE WEEK

MOVES INTO CENTRAL NC AT SOME POINT ON TUESDAY ALTHOUGH CONFIDENCE

IN TIMING IS LOW AT THIS POINT...WILL ADJUST CURRENT FORECAST TO

INTRODUCE EARLIER POPS ON TUESDAY...AFTER 12Z. A BRIEF HIT OF SNOW

ON THE ONSET WOULD TRANSITION TO RAIN AS TEMPERATURES WARM INTO THE

MID 40S BY AFTERNOON. STILL TOO EARLY FOR SOLID QPF AMOUNTS AT THIS

POINT. THERE WILL BE A LULL IN PRECIPITATION TUESDAY NIGHT BEFORE

THE APPROACH OF THE MORE SIGNIFICANT LOW ON WEDNESDAY. LOWS TUESDAY

UPPER 20S TO MIDDLE 30S.

WEDNESDAY AND THURSDAY: EARLY WEDNESDAY A STRONG 1034 MB HIGH SETS

UP IN A FAVORABLE LOCATION FOR A CLASSICAL OR HYBRID COLD AIR

DAMMING EVENT WITH A WEDGE FRONT OVER THE PIEDMONT OF NC.

MEANWHILE...INITIAL DEVELOPMENT OF THE LOW PRESSURE SYSTEM THAT WILL

EVENTUALLY SKIRT THE CAROLINA COAST BEGINS IN THE NORTHERN GULF OF

MEXICO. VERY GOOD MOISTURE TRANSPORT ENSUES AS AN UPPER LEVEL TROUGH

DIPS ALL THE WAY DOWN INTO THE SOUTHERN GULF OF MEXICO...PROMOTING

WELL ABOVE NORMAL PRECIPITABLE WATER VALUES. MODELS DIFFER

CONSIDERABLY IN THE HANDLING OF THE SYSTEM FROM HERE ON OUT WITH THE

GFS FAVORING A MILLER A SCENARIO WITH THE LOW OFFSHORE AND THE ECMWF

LOOKING CLOSER TO A MILLER B OR A/B. THIS WILL AFFECT P-TYPE WITH

THE GFS LOOKING MORE LIKE ALL SNOW EARLY ON BUT QUESTIONS ARISE

LATER AS SATURATION DIPS BELOW THE -10C LEVEL. THE EC SOLUTION

OFFERS MORE OF A MIXED BAG OF P-TYPE CORRIDORS AS THE SYSTEM CROSSES

THE AREA...MAKING ANY GUESSES AT ACCUMULATIONS NEAR IMPOSSIBLE AT

THIS POINT.

A LITTLE BIT BETTER CONFIDENCE IN THE TIMING OF THE SYSTEM WITH

BIGGEST IMPACTS OCCURRING LATE AFTERNOON WEDNESDAY THROUGH EARLY

THURSDAY MORNING. WPC FAVORS A BLEND OF THE GEFS AND ECENS ENSEMBLE

MEANS WHICH CENTERS THE LOW OVER EXTREME NORTHEASTERN NORTH CAROLINA

AT 12Z THURSDAY. WHILE THERE IS HIGH VARIABILITY IN THE

DETERMINISTIC MODELS AT THIS POINT...THESE ENSEMBLE MEANS HAVE BEEN

FAIRLY CONSISTENT OVER THE LAST SEVERAL RUNS AND OFFER REASONABLE

CONFIDENCE IN SOME KIND OF A WINTER EVENT OVER CENTRAL NC WEDNESDAY

INTO THURSDAY. HIGHS IN THE UPPER 30S TO UPPER 40S BOTH DAYS WITH

LOWS IN THE LOW TO MID 30S WEDNESDAY NIGHT.

**kind of funny them mentioning that this looks like a Miller A/B; from our discussions yesterday.

[RevDodd]

I've been impressed with the consistency and general agreement this far out in the models. Biggest ?? have come with temps, and that varies a bit with the in-house tendencies and how they're handling HP to the north. 

 

It may make it tough to warn folks in potential ice areas ... but after the mess down in Bama-Ga, I bet we'll see cities and school districts err on the side of caution next week.

[NavarreDon]

GSP's overnight with some interesting wording about the 0Z euro run:

 

THE PATTERN BECOMES MORE DYNAMIC TUE THROUGH WED NIGHT AS AN AREA OF
ULVL CONFLUENT FLOW SETS UP ACROSS THE EAST COAST AND HELPS ANCHOR A
WEDGING 1033 MB HIGH ACROSS SRN NEW ENG. MEANWHILE...INCREASING H5
VORT ADV AHEAD OF A S/W TROF WILL BEGIN TO INDUCE SFC CYCLOGENESIS
ACROSS THE NRN GOM SOMETIME TUE AFTERNOON THROUGH WED MORNING
DEPENDING UPON WHICH GUIDANCE IS FAVORED. PARTIAL THICKNESSES AND
MODEL SOUNDINGS SHOW A DEEPLY COLD ATMOS IN PLACE BY 06Z TUE AND
PROFILES SHOULD REMAIN MOSTLY BELOW FREEZING INTO EARLY THU.

THE OP MODELS ARE SHOWING SOME SIGNS OF A CONSENSUS AS FAR AS THE
TIMING OF THE MLVL WAVE...HOWEVER THERE ARE STILL SIGFNT DIFFERENCES
WRT TO PARTIAL THICKNESSES AND THE AVAILABLE MOISTURE WITH THIS
EVENT. THE LATEST ECMWF SOLN IS NOW MORE AKIN TO THE MILLER-A
SCENARIO OF THE GFS...HOWEVER IT STILL HAS A SLOWER PROGRESSION AND
MUCH HIGHER MOISTURE FLUX THAN THE OTHER MODELS. THIS SEEMS A LITTLE
OVERDONE AND IS LIKELY DUE TO THE TRANSITION OUT OF IT/S EARLIER
SYNOPTIC CONFIG. IN ANY CASE...THE THERE IS PLENTY OF QPF RESPONSE
AGREEMENT TO MAINTAIN THE HIGH END CHANCE POPS TUE NIGHT THROUGH
WED. DUE TO VARYING THERMAL TIMINGS...PARTIAL THICKNESSES WERE
BLENDED BTW THE GFS/ECMWF...WHICH GAVE A -SN/ZR MIX NOMOGRAM ACROSS
THE NRN ZONES TUE NIGHT...BECOMING MORE OF A SNOW EVENT FARTHER
SOUTH INTO THE UPSTATE AND NE GA AFTER DAYBREAK WED AS THE COLD
WEDGE STRENGTHENS AND THE MLVLS REMAIN MOIST AND SUSTAINED BELOW
FREEZING. ACCUMULATING SNOW LOOKS POSSIBLE ACROSS ALL BUT THE SRN
TIER ZONES...YET AMOUNTS AT THIS STAGE ARE STILL UP IN THE AIR DUE
TO MODEL LAYERED MOISTURE AND TIMING SPREADS. WILL COUNT ON MOISTURE
WANING WED NIGHT AS THE SYSTEM PULLS NE AND H85 WAA PERHAPS CREATING
ANOTHER PERIOD OF -ZR ACROSS THE NC FILLS AND PIEDMONT INTO EARLY
THU. MAX TEMPS WILL BE COLD...ABOUT 10-15 DEGREES BELOW NORMAL IN
THE WEDGE...WITH MINS A CAT OR SO BELOW NORMAL.

[msuwx]

Great video as always Matt! Thanks for taking the time to put those together. 

Thanks! Sure thing... happy to do it.

[Cold Rain]

DGEX is another big hit.  Somebody post a clown map in Banter, please!

[HWY316wx]

From the FFC last night:

 

THE EUROPEAN MODEL WITH A CAD AIRMASS AND
OVERRUNNING SCENARIO SETTING UP AND PRODUCING A COLD RAIN.
HOWEVER...TEMPERATURES ARE CLOSE TUESDAY NIGHT FOR SOME TYPE OF
WINTER MIX FAVORING SNOW AND FREEZING RAIN FOR A FEW OF THE FAR
NORTHERN COUNTIES. SURFACE LOW PRESSURE MOVES TO E COAST THURSDAY
MORNING GREATLY DIMINISHING PRECIP CHANCES ACROSS THE AREA. ONCE
AGAIN TEMPERATURES CLOSE WEDNESDAY NIGHT FOR SOME TYPE OR MIX
FAVORING RAIN AND SNOW.