Feb. 18-20, 2012 Disco/Analysis

[IWC]

32 in Raleigh I'm sure your colder...

what are the lows for Sunday night?

[GaWx]

I realize that, but someone said the Euro was giving richmond 12"+. That map sure didn't show 12"+.

Someone did say that. It actually gives Richmond ~6", which I assume is still a major storm by their standards.

[burgertime]

12z Euro / GEM....interesting. That's kind of why I left the window cracked for the northern foothills and VA border areas my AM discussio/ video, but snow gets even further south that than on these models.

On the Euro, 850s don't just get a tiny amount below 0 up in northern NC....they plunge to at least -4 before the precip ends. SFC temps in the 30s Sunday afternoon in that area verbatim.

Interesting that the GFS Ens precip type map somebody posted lines up remarkably well with the snow accum maps from Wunderground.

Of interest is what Phil said in the discussion over on the main weather side, there could be yet another piece of energy to watch in 24 hours showing up on the modeling. This is going to be a down to the wire event for many. I just hope some of us in the CLT area can get lucky and catch a passing flizzard as this thing high tails it out.

[tarheelwx]

It's a 3 hour map, you'd have to total up all the three hour increments to know the total.

Okay. That makes more sense now. Which 3 hours? Obviously it makes a big difference.TW

[packbacker]

Someone did say that. It actually gives Richmond ~6", which I assume is still a major storm by their standards.

Not sure what the ratio's would be, but it's almost 1" of QPF for Richmond with very cold 850's (-4 to -8). 6" of snow would be 6 to 1 to ratio's, seems kind of low, but doesn't matter, it would be a great event for Richmond.

[griteater]

Latest from HPC...

UPDATES FROM THE 12Z GUIDANCE...

WITH REGARD TO THE POTENTIAL WINTER STORM ACROSS THE

MID-ATLANTIC...THERE WAS A TREND NOTED WITH THE ARRIVAL OF THE

SUITE OF 12Z GUIDANCE. THE MOST PRONOUNCED SHIFT WAS SEEN IN THE

12Z ECMWF WHICH SEEMED TO BACK UP THE CYCLONE A GOOD 6 HR IN

PROGRESSION COMPARED TO THE 00Z ECMWF RUN. THIS PLACES IT CLOSER

TO WHERE THE 12Z/00Z UKMET...BUT STILL NOT AS FAR SOUTH AND WEST

AS THE 12Z CMC WHICH MAINTAINED ITS POSITION FROM EARLIER. THE 12Z

GFS NOW RESIDES ON THE EASTERN FRINGE OF THE MODEL SPREAD WITH A

SOLUTION THAT LOOKS VERY MUCH LIKE THAT OF ITS PRECEDING RUN AS

WELL AS THE 12Z/06Z GEFS MEAN. TO ACCOUNT FOR THE TRENDS IN THE

12Z MODELS...THE FRONTAL SYSTEM WAS SLOWED A TAD WHICH PLACES IT

CLOSER TO THAT OF THE 12Z GFS.

[rduwx]

I wrote this storm off 2 days ago but I have to admit this shift south has peaked my interest. I'm still not excited but it's not out of the realm of possibilities that we could have another shift south. If we can get another small shift south and keep the strength of the lp, things could get interesting.

[msuwx]

Of interest is what Phil said in the discussion over on the main weather side, there could be yet another piece of energy to watch in 24 hours showing up on the modeling. This is going to be a down to the wire event for many. I just hope some of us in the CLT area can get lucky and catch a passing flizzard as this thing high tails it out.

Interesting developments for sure. Even though people get sick of hearing it, when you are dealing with this many moving pieces, you have to keep options open right up until the final 24 hours before the event.

When you are dealing with a single piece of energy, little or no phasing, more stable pattern.....you can have confidence further in advance. In a case like this, different ball game.

I might have closed the door (at least pushed the door to) on the possibility of some flakes in the I-40 corridor too quickly....maybe even further south. Trends can go many different ways from this point.

[SnowGator]

Of course now the 12z euro makes me look even worse now for my comment lol! I hope I am wrong and I agree that one more euro shift like that and the RDU area could be looking interesting. I would LOVE to be proven wrong here!

I always enjoy reading the educated thoughts of the mets on here, and I thought your apology was very gracious. I think most on here hope for the best and kind of expect the worst (or at least the same old same old). I also enjoy reading the hopeful posts of the weenies (for the most part!).

I have not seen any snow this year IMBY but I did happen to be in MD one weekend in January when they got their first snow - maybe their only snow so far - so I consider myself pretty lucky at this point.

[griteater]

GSP Update...

.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/...

AS OF 215 PM THURSDAY...12Z GFS AND 00Z ECMWF IN DECENT AGREEMENT

REGARDING SYSTEM FOR SAT-SUN WITH THE SLOWER NAM POORLY INITIALZED

AND CONSIDERED AN OUTLIER. THE 12 ECMWF ALSO INITLIALZED POORLY SO

IT WAS NOT USED. AS H5 SHORTWAVE TROF MOVES ACROSS TX FRI NIGHT INTO

SAT...MOISTURE WILL SURGE N OUT OF THE GULF AND UP OVER THE CWA BY

SAT AFTN-EVE. GOOD S UPSLOPE FLOW AND ISENTROPIC LIFT WILL AID IN

PRECIP PRODUCTION WITH A SLIGHT CHC DEVELOPING ALONG THE W

ESCARPMENT SAT MRNG...QUICKLY INCREASING TO SOLID CHC WITH SLIGHT

CHC SPREADING ACROSS THE CWA. WEAK WEDGE OVER THE AREA WILL GET SOME

IN-SITU ENHANCEMENT AS DEEPER MOISTURE CONTINUES TO SURGE N WITH

TEMPS STAYING SLIGHTLY BELOW AVG. EXPECT LIKELY POPS TO THEN SPREAD

ACROSS THE AREA THRU THE AFTN WITH A PERIOD OF CAT POPS INTO EARLY

SUN MRNG. BEST QPF LIES S OF THE CWA AND HAVE 1 TO 1.5 INCH TOTALS

ACROSS THE S TIER BY YHE TIME PRECIP TAPERS OFF FROM THE SW DURING

THE DAY SUN. COOLER AIR WILL ALSO WRAP AROUND THE SFC LOW AS IT

TRACKS ALONG THE S CWA...WITH A PERIOD OF LGT SNOW EXPECTED OVER THE

MTNS. ACCUMS OVER THE HIGHER PEAKS AND RIDGES COULD REACH 2 IN

BEFORE PRECIP DIMINISHES TO SLIGHT CHC LATE SUN AFTN. HIGH TEMPS SUN

SHOULD BE BELOW AVG.

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...

AS OF 218 PM THURSDAY...AN AREA OF DEFORMATION ZONE PCPN IS EXPECTED

TO EXIT THE FA AROUND 00 UTC MONDAY. THERE IS SOME UNCERTAINTY AS TO

HOW DEEP THE WAVE WILL BE...AND IT IS POSSIBLE THAT PCPN...MAINLY IN

THE FORM OF SNOW...COULD LAST A WHILE LONGER THAN WHAT/S CURRENTLY

IN THE FORECAST FOR THE NC ZONES SUNDAY NIGHT.

[BrierCreekWx]

Interesting developments for sure. Even though people get sick of hearing it, when you are dealing with this many moving pieces, you have to keep options open right up until the final 24 hours before the event.

When you are dealing with a single piece of energy, little or no phasing, more stable pattern.....you can have confidence further in advance. In a case like this, different ball game.

I might have closed the door (at least pushed the door to) on the possibility of some flakes in the I-40 corridor too quickly....maybe even further south. Trends can go many different ways from this point.

I may end up being guilty of that as well, although I never discounted central NC seeing a few flakes I certainly had shut the door on accumulating snow...but I can't honestly say it's impossible now based on the 12z runs. However, I still firmly believe it would be a low impact situation with roads being only wet regardless.

One thing that surprises me is that with the 50/50 low not as impressive as in some previous forecast, and no real cold high to the north, that the cold air is being modeled to rush in so quickly. Normally, that scenario does not bode well for central NC, and I'm still skeptical it will amount to much more than a brief changeover, but who knows. If trends continue, then we might have something more substantial to talk about.

[burgertime]

GSP Update...

.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/...

AS OF 215 PM THURSDAY...12Z GFS AND 00Z ECMWF IN DECENT AGREEMENT

REGARDING SYSTEM FOR SAT-SUN WITH THE SLOWER NAM POORLY INITIALZED

AND CONSIDERED AN OUTLIER. THE 12 ECMWF ALSO INITLIALZED POORLY SO

IT WAS NOT USED.

Well that's a bummer. Wonder what caused the issues on the Euro. Either way with so much energy they are right not to trust any model that has problems initializing

[WeatherNC]

99% chance this won't happen, but here is the best member....Avert your eyes unless you can handle the disappointment on Sunday.

I would say 80% chance that won't happen, but take a sec and compare that to the 12z EC clown map from wunderground, not really that far off... We do not want this gulf low to make it into N GA, period. Tracks needs to be through central GA giving the dominant coastal reflection coming off somewhere around CHS - Myrtle Beach (don't have to go far back to see this happening, even a couple GFS mems have it from 12z). 12z Euro has a 1000mb low near La Grange GA at 72hrs, with evidence of a transfer beginning off the Carolina coast based on the tugging of the isobars, possibly a strung out mess who knows. Just for comparison, 0z Euro had a ~996 about 75 miles east of Elizabeth City, 12z ~1000mb between Florence and ILM, both runs valid 1pm Sunday. Trough axis, Euro looks more neg tilt this run through AL/GA compared to 0z, maybe just seeing things, but pretty sure it does. This run is about 6hrs slower than 0z, shifted slightly s and e of position in SE NC/NE SC, and about 4C colder at 850 on a line from ORF to CLT. Also looks like a cleaner transfer compared to 0z when viewing the surface maps valid 7am 0z vs 1pm 12z Sunday (remember this run was about 6hrs slower). 0z still had a 1000mb closed isobar in extreme NE GA in addition to the closed low at the coast. 12z surface reflection is more consolidated along the coast with pressures in the 1008mb range in N GA where the 0z run had something still lagging. Will get into the H5 and 850 stuff a little later, but based on the surface, quick recap of the Euro and what to watch for going forward.

[BrierCreekWx]

Well that's a bummer. Wonder what caused the issues on the Euro. Either way with so much energy they are right not to trust any model that has problems initializing

Here comes the weenie out in me: the 12z Canadian (although it's been fairly consistent), and even the GFS all followed the same trends. Are we looking at another 12/25-26, 2010 where everything is discounted that shows a trend towards something more wintry? Time will tell haha.

[packbacker]

Well that's a bummer. Wonder what caused the issues on the Euro. Either way with so much energy they are right not to trust any model that has problems initializing

Interesting, if it would have been better initialized it would have probably been even better for us, probably even further SE! The GFS OP run is the furthest NW of any other model, it's ENS mean is very close to what the Euro just showed, the CMC is slower and on similar path.

[burgertime]

Here comes the weenie out in me: the 12z Canadian (although it's been fairly consistent), and even the GFS all followed the same trends. Are we looking at another 12/25-26, 2010 where everything is discounted that shows a trend towards something more wintry? Time will tell haha.

I really hope your right even if I don't see anything! I guess and this is my lack of education on this, wouldn't the fact that it can't initialize correctly have a significant impact on it's depiction of what will happen due to so much interaction (or lack thereof) of energy? Or is it less of a factor? I really have little clue as to initialization processes and such.

[RaleighWx]

Someone did say that. It actually gives Richmond ~6", which I assume is still a major storm by their standards.

I have seen the vendor snowfall graphic map. It shows an area of 4-8 icnhes covering most of central and southern Va with 2-4 across the SE Va coastal sections, and not much at the immediate coast.

Over NC, the 4-8 band is right along the NC border bleeding over into those immediate counties from the northern mountains to probably Roxboro. Then an area of 2-4 inches from the northern foothills through the northern piedmont and northern coastal area. The accumulations are only plotted at 2+ inches and judging by the wunderground images, there is an area of a dusting to 2 inches just south of that area around the latitude of the Triangle north.

[WeatherNC]

Well that's a bummer. Wonder what caused the issues on the Euro. Either way with so much energy they are right not to trust any model that has problems initializing

I am lost on this one, if the Euro was an outlier than yeah I could see some sort of initialization problems messing up the solution, but when it matches up nicely with the 12z UKMET & Canadian inside day 4, seriously, are all three that far off. If you have to make a forecast today for this event, take an equal blend of those three and call it a day. Likely the most probable outcome based on all available information up until this point, and there is good continuity between them. Canadian likely gets bonus points as it has been the most consistent, and UKMET/Euro trended toward it today.

Remember that HPC disco prior to the 12/26 storm last year, 48 hrs out when the models started to bring it back, what was it; "all the models appear to be suffering from feedback?"

Don't be surprised if we are seeing a trend back towards the original solution that was advertised last Fri/Sat, albeit less extreme, which in this case would imply warmer. Don't know why this happens but my suspicion is upper air ingest somewhere outside of the US, parcels get over a data sparse region for the mid term leading to model-mayhem, and once they are completely sampled on American soil we see it trend back. Yeah I know much more going into the models than RAOB stuff, such as data from satellites and what not, but I have no better explanation as to why this is the case.

[Dunkman]

Well that's a bummer. Wonder what caused the issues on the Euro. Either way with so much energy they are right not to trust any model that has problems initializing

I'm not sure of what to make of that from GSP. No one here, and I'm reading quite a few subforums, have mentioned the initialization errors. Additionally, like has been mentioned, all the other models are trending in this direction, with the 12z GFS ensemble mean looking very much like the 12z operational Euro.

[RaleighWx]

Well that's a bummer. Wonder what caused the issues on the Euro. Either way with so much energy they are right not to trust any model that has problems initializing

Not sure what this forecaster is seeing.

http://raleighwx.americanwx.com/models/euro/12zeuro500mbHGHTNA000.gif

http://raleighwx.americanwx.com/models/gfs/12zgfs500mbHGHTNA000.gif

The initializations of the GFS/Euro look the same to me.

With that said, with the oscillations still occurring, confidence is low. The forecaster may should have just said, the Euro is a departure from it's previous run and for now we will stay with the GFS solution.

[SnowGator]

Here comes the weenie out in me: the 12z Canadian (although it's been fairly consistent), and even the GFS all followed the same trends. Are we looking at another 12/25-26, 2010 where everything is discounted that shows a trend towards something more wintry? Time will tell haha.

Now you're just stirring the pot lol!

[franklin NCwx]

Well that's a bummer. Wonder what caused the issues on the Euro. Either way with so much energy they are right not to trust any model that has problems initializing

We heard that same garbage with the Christmas storm that the gfs was bringing back.

[NavarreDon]

GSP Update...

.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/...

AS OF 215 PM THURSDAY...12Z GFS AND 00Z ECMWF IN DECENT AGREEMENT

REGARDING SYSTEM FOR SAT-SUN WITH THE SLOWER NAM POORLY INITIALZED

AND CONSIDERED AN OUTLIER. THE 12 ECMWF ALSO INITLIALZED POORLY SO

IT WAS NOT USED. AS H5 SHORTWAVE TROF MOVES ACROSS TX FRI NIGHT INTO

SAT...MOISTURE WILL SURGE N OUT OF THE GULF AND UP OVER THE CWA BY

SAT AFTN-EVE. GOOD S UPSLOPE FLOW AND ISENTROPIC LIFT WILL AID IN

PRECIP PRODUCTION WITH A SLIGHT CHC DEVELOPING ALONG THE W

ESCARPMENT SAT MRNG...QUICKLY INCREASING TO SOLID CHC WITH SLIGHT

CHC SPREADING ACROSS THE CWA. WEAK WEDGE OVER THE AREA WILL GET SOME

IN-SITU ENHANCEMENT AS DEEPER MOISTURE CONTINUES TO SURGE N WITH

TEMPS STAYING SLIGHTLY BELOW AVG. EXPECT LIKELY POPS TO THEN SPREAD

ACROSS THE AREA THRU THE AFTN WITH A PERIOD OF CAT POPS INTO EARLY

SUN MRNG. BEST QPF LIES S OF THE CWA AND HAVE 1 TO 1.5 INCH TOTALS

ACROSS THE S TIER BY YHE TIME PRECIP TAPERS OFF FROM THE SW DURING

THE DAY SUN. COOLER AIR WILL ALSO WRAP AROUND THE SFC LOW AS IT

TRACKS ALONG THE S CWA...WITH A PERIOD OF LGT SNOW EXPECTED OVER THE

MTNS. ACCUMS OVER THE HIGHER PEAKS AND RIDGES COULD REACH 2 IN

BEFORE PRECIP DIMINISHES TO SLIGHT CHC LATE SUN AFTN. HIGH TEMPS SUN

SHOULD BE BELOW AVG.

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...

AS OF 218 PM THURSDAY...AN AREA OF DEFORMATION ZONE PCPN IS EXPECTED

TO EXIT THE FA AROUND 00 UTC MONDAY. THERE IS SOME UNCERTAINTY AS TO

HOW DEEP THE WAVE WILL BE...AND IT IS POSSIBLE THAT PCPN...MAINLY IN

THE FORM OF SNOW...COULD LAST A WHILE LONGER THAN WHAT/S CURRENTLY

IN THE FORECAST FOR THE NC ZONES SUNDAY NIGHT.

Different Mets. wrote the short term & long term in this update. Not sure how this works as far as input from other mets but, it seems to me like their might be some subtle disagreement. As I have said many times before, the long term writer is imo the best winter met at GSP. Probably reaching here but who knows.

[BrierCreekWx]

I really hope your right even if I don't see anything! I guess and this is my lack of education on this, wouldn't the fact that it can't initialize correctly have a significant impact on it's depiction of what will happen due to so much interaction (or lack thereof) of energy? Or is it less of a factor? I really have little clue as to initialization processes and such.

Oh no, you're 110% right if it indeed did have initialization problems, then the entire forecast from it in theory would be based on bad data. I guess what I was getting at was that HPC mentioned the 12z and 18z 12/24/2010NAM/GFS all initialized wrong back with the Christmas storm when they began to trend back towards a more phased and wintry scenario. I have never understood that, as those models continued to only look more wintry on the 12/25 00z runs, and so I guess I am throwing out the challenge flag on that event, and potentially today's declaration of poor initialization. It's like WeatherNC just mentioned, we've really got some problems now if one model initialized poorly and it's trending towards two other models!

Edit: I wrote this assuming that this was taken from HPC's model diagnostic discussion, but in reading it I don't see where they've mentioned the 12z Euro had intializaton errors, although it may have been derived from this:

...WITH MID-LEVEL DIAGNOSTICS FIELDS FROM THE GFS ALIGNING

BEST WITH THE STRUCTURE SEEN ON WATER VAPOR IMAGERY COMPARED TO

THE NAM AND ECMWF...WHICH APPEAR WORST. AMONG THE REMAINING

SOLUTIONS...THE CANADIAN PRODUCES AN OUTLIER SOLUTION CROSSING THE

GULF COAST AND THUS IS DISCARDED...WHILE THE UKMET IS VERY MUCH

LIKE THE NAM/ECMWF BUT HAS A TENDENCY TO OVER-DEVELOP OR DEEPEN

CYCLONES. THUS...CONFIDENCE IN THE UKMET IS LOW.

[Poimen]

Oh no, you're 110% right if it indeed did have initialization problems, then the entire forecast from it in theory would be based on bad data. I guess what I was getting at was that HPC mentioned the 12z and 18z 12/24/2010NAM/GFS all initialized wrong back with the Christmas storm when they began to trend back towards a more phased and wintry scenario. I have never understood that, as those models continued to only look more wintry on the 12/25 00z runs, and so I guess I am throwing out the challenge flag on that event, and potentially today's declaration of poor initialization. It's like WeatherNC just mentioned, we've really got some problems now if one model initialized poorly and it's trending towards two other models!

Yes, I remember that very clearly. And I remember thinking to throw out the runs because of it. Of course, as always only time will tell. Tonight's runs will probably go a long way toward clearing up the matter, I hope.

[RaleighWx]

The 12z Euro Ensemble mean is much slower/further south than the 00z Euro ensemble mean.

When compared with the 12z operational ECMWF it is slightly quicker and slightly further north.

But I think it shows the Euro is not an outlier withing its own ensemble and the shift/trend could be real. Of course we need to see the trend continue in the next couple of cycles to get too excited.

[tnweathernut]

The 12z Euro Ensemble mean is much slower/further south than the 00z Euro ensemble mean.

When compared with the 12z operational ECMWF it is slightly quicker and slightly further north.

But I think it shows the Euro is not an outlier withing its own ensemble and the shift/trend could be real. Of course we need to see the trend continue in the next couple of cycles to get too excited.

I think even without a trend someone could end up with a modest snow in Tennessee after seeing all the 12z guidance. It's already really close over this way, surprisingly.

[msuwx]

The 12z Euro Ensemble mean is much slower/further south than the 00z Euro ensemble mean.

When compared with the 12z operational ECMWF it is slightly quicker and slightly further north.

But I think it shows the Euro is not an outlier withing its own ensemble and the shift/trend could be real. Of course we need to see the trend continue in the next couple of cycles to get too excited.

Yeah, the Euro ensemble mean and operational are in very good agreement overall with out system at 72 and 84 hours. Here's the 72 hour comparison.

Operational

Ensemble mean

Just put up a quick post on the blog....just updating the midday trends.

[HKY_WX]

All you had to do was look at the overall 5h NA setup to know there was always a good chance here. All the pieces are in place and it will generally take the models until inside 2 days to get it exact. This was never and will never be an apps runner. It was always going to be a close call and those saying otherwise are misinformed.

[HKY_WX]

btw the euro is probably droppnig 4-8 as far south as martinsville va.