The weekend storm.

[usedtobe]

While I've been on record as saying that I thought there was little chance of this system bringing us snow. I'll admit to some uncertainty after seeing the ukmet. If you follow verification scores very closely, the euro is tops, the ukmet 2nd and the GFS third but the differences aren't that great and the euro and ukmet have both had wins in the recent past. What's a little disconcerting is you can't reall see anything uptream or downstream for the shortwave (the system) that helps explain the huge dichotomy of solutions. Making it even worse is the GFS ensembles which pretty much cover all the solutions offered in the images shown below.

If anything, the models have diverged instead of converged this run.

I still think the ukmet is an outlier but it has my interest. As I've said before, I sometimes am wrong and in this case might have become too certain too quick. Time will tell.

[mitchnick]

I'd be happy with a change to snow and "some" accumulation. In a typical year around here, that would be considered normal for early DEC. The cold that follows would have what little fell hang around a while, subject more to sublimation than melting, which is always the more desirable way to loose snow cover imwo.

[Ellinwood]

FWIW, most of the models brought this latest weak disturbance entering the Gulf too far south... what was supposed to be mostly sunny 3 days ago in AL/GA is mostly cloudy or overcast right now, with some showers moving along the coast.

[yoda]

I know these are the fun maps... but its interesting to note that they still try to give the DCA area 1-2 inches of snow

[Ellinwood]

I like how all of Wes' discussions get pinned within the hour of the OP.

Maybe we'll have another event where the UL cuts-off and a pocket of vorticity rolls around the loop and makes a SW dive-bomb into the 40S territory...but that's usually only when we get the favored blocking by the -NAO.

[yoda]

Hey Wes, do the ensembles of the GFS have a higher score than the OP? Interesting to note that its not just one or two that are trying to give us snow, but now its closing in on half of the ensembles...

http://www.meteo.psu.edu/~gadomski/ENSPRSNE_12z/ensprsloopmref.html

[Ellinwood]

Hey Wes, do the ensembles of the GFS have a higher score than the OP? Interesting to note that its not just one or two that are trying to give us snow, but now its closing in on half of the ensembles...

http://www.meteo.psu...rsloopmref.html

To answer: Yes, the ensemble does better. Both the GFS and ECMWF ensembles do better than their respective Op counterparts.

[yoda]

The zones are starting to get quite interesting... LWX basically has rain/freezing rain/snow for I-95 and W now

[usedtobe]

I like how all of Wes' discussions get pinned within the hour of the OP.

Maybe we'll have another event where the UL cuts-off and a pocket of vorticity rolls around the loop and makes a SW dive-bomb into the 40S territory...but that's usually only when we get the favored blocking by the -NAO.

I'm surprised this one did because it's really not much of a discussion. I'll be interested in seeing what the euro ensemble members do. You're right about the southern system, it was supposed to be quite a bit farther south than where it ended up. My guess is the ukmet is too far south with its closed low, that seems to be the more frequent error with upper lows as opposed to forecasting them too far north.

[yoda]

Afternoon disco is nice... but they key quite alot on the GFS

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...

-- Changed Discussion --SHORTWAVE H8 RIDGE-SFC HIPRES BRIEFLY BUILDS INTO THE AREA SAT. HIGH

TEMPS SAT WILL APPROACH NORMAL READINGS. HI CLOUDS WILL INCREASE

THRUOUT THE DAY SAT AS A DEVELOPING STORM SYSTEM OVER THE CENTRAL

PLAIN/MIDWEST APPROACHES.

THE AFOREMENTIONED STORM SYSTEM WILL BECOME BETTER ORGANIZED ONCE IT

MOVES EAST OF THE MS RIVER SAT NGT INTO SUN AS A STRONG UPPER-LVL

JET STREAK DIGS AROUND THE BACKSIDE OF THE AMPLIFYING TROUGH. THE

12Z GFS DETERMINISTIC RUN AND ITS ENSEMBLES HAVE SHIFTED THE TRACK

OF THE LOW NOTABLY SOUTHEAST OF PREVIOUS RUNS...WHICH NOW HAS THE

TRACK OF THE SFC LOW UP THE THE MID-ATLANTIC COAST. THIS SOUTHEAST

TREND OF THE GFS MODEL SUITE SUBSEQUENTLY INCREASES THE DIFFERENCES

BETWEEN THE LAST FEW RUNS OF THE ECMWF...WHICH HAVE THE SFC LOW

TRACK CLOSER TO THE OH VLY AND GREAT LAKES REGION. THE ACTUAL TRACK

OF THE LOW WILL DEPEND ON THE PHASING BETWEEN THIS SYSTEM AND A

TRAILING NRN STREAM ENERGY ASSOCIATED WITH THE POLAR VORT.

DUE TO THE UNCERTAINTY IN EVOLUTION/TRACK OF THE STORM...HAVE TAKEN

A MORE PROBABILISTIC APPROACH TO THE PTYPE FORECAST. ATTM...IT

APPEARS THE BEST CHANCE TO SEE A WINTRY MIX AT THE START OF THE

EVENT SAT NGT WILL BE WEST OF I-95...WITH RAIN THE PREDOMINANT PTYPE

FARTHER EAST. AS LLVL WARM AIR WRAPS INTO THE SYSTEM...A WINTRY MIX

MAY CONTINUE ALONG AND WEST OF THE BLUE RIDGE ON SUN WITH RAIN TO

THE EAST. WILL HIGHLIGHT WINTRY MIX THREAT IN THE HWO.

ONCE THE CLOSED LOW MOVES NORTHEAST OF THE REGION...NW FLOW ON THE

BACKSIDE OF THE LOW WILL DRAW A STRONG COLD FRONT THRU THE REGION

SUN NGT. ANY LINGERING PRECIP MAY BRIEFLY TURN TO ALL SNOW SUN NGT

BEFORE ENDING LATE.

[Ender]

To answer: Yes, the ensemble does better. Both the GFS and ECMWF ensembles do better than their respective Op counterparts.

The ensemble mean does better than the OP, but there are some but's...

Last I read:

• The EGFS and EEC outperform their OP counterparts in the 168+ FHR time frame, but not necessarily in the <120hr time frame.
• No single ensemble member tends to outperform the OP. The OP beats the individuals.
• The real edge seen by the ensemble mean in the longer range is in the tendency of that mean to dampen out high SD events that are less likely to verify at 186hr.
• The OP tends to handle "unusual" (high SD events) better in the very short range than do the ensemble clusters, and I'd say that's what we have here...several clusters of ensemble solutions.

But...that is pretty dated info. As in circa 2007.

[ThePhotoGuy]

NWS HWO

DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

THERE IS A POSSIBILITY OF A MIX OF WINTRY PRECIPITATION SATURDAY

NIGHT AND SUNDAY FOR AREAS WEST OF INTERSTATE 95. AT THIS TIME...

THERE IS A SIGNIFICANT UNCERTAINTY IN THE TRACK OF THE SYSTEM...

WHICH ULTIMATELY WILL DICTATE PRECIPITATION TYPE FOR THE AREA.

STAY APPRISED OF THE LATEST FORECASTS FOR THIS POTENTIAL WEATHER

EVENT.

[yoda]

18z NAM looks like it would want to go further east.... the PV is north and the s/w weaker I think... but then again.. its at the 78-84 hr range of the NAM

[usedtobe]

The euro ensemble mean remains very euro looking and not good for our area. While I don't have the individual members, the look of the mean suggests they are not showing as much divergence as the GFS ens mean

[Ian]

18z NAM looks like it would want to go further east.... the PV is north and the s/w weaker I think... but then again.. its at the 78-84 hr range of the NAM

not even worth discussing.

[Ian]

i always have a hard time going against the euro. there may be some middle ground but i doubt the gfs will keep "trending" better.

[usedtobe]

not even worth discussing.

But also wrong. Look at where the 850 low already is.

[usedtobe]

i always have a hard time going against the euro. there may be some middle ground but i doubt the gfs will keep "trending" better.

I pretty much agree though the ukmet does worry me some but if I were making a forecast, I'd go for somewhere between the two models. The gfs does seem to have a tendency to not track these type systems far enough west.

[Ian]

But also wrong. Look at where the 850 low already is.

yeah that's not too pretty for this area. people forget to look at the different levels.

[yoda]

yeah that's not too pretty for this area. people forget to look at the different levels.

I did... the 5h energy still seems to moving south or SE still. I was thinking that the 850 low would just barrel east. Look, I just want to see some flakes damn it

[Ender]

The ensemble mean does better than the OP, but there are some but's...

Last I read:

• The EGFS and EEC outperform their OP counterparts in the 168+ FHR time frame, but not necessarily in the <120hr time frame.
• No single ensemble member tends to outperform the OP. The OP beats the individuals.
• The real edge seen by the ensemble mean in the longer range is in the tendency of that mean to dampen out high SD events that are less likely to verify at 186hr.
• The OP tends to handle "unusual" (high SD events) better in the very short range than do the ensemble clusters, and I'd say that's what we have here...several clusters of ensemble solutions.

But...that is pretty dated info. As in circa 2007.

I've been digging around for the article that I was trying to reference for the above. Can't find it. I did, however, find reference to the ensemble mean outperforming the OP model, over the long term, for FH 48 and beyond. Thus the OP, slightly, outperforming the mean inside 48hr.

[Ian]

I did... the 5h energy still seems to moving south or SE still. I was thinking that the 850 low would just barrel east. Look, I just want to see some flakes damn it

it would have to do something more than just barrel east at that point.. it's in a position to pass over or north of us and strengthening in the latter panels.

[usedtobe]

I did... the 5h energy still seems to moving south or SE still. I was thinking that the 850 low would just barrel east. Look, I just want to see some flakes damn it

So do it, but to me the look of the nam 500 wouldn't save us and would not give a solution anywhere near the ukmet which is pretty much what we need. That said, it's the 84 hr nam so it could amp up on subsequent runs.

[Ender]

not even worth discussing.

...but it has a 1004mb low over N central Mississippi. Can't we just discuss it a little bit? Of course it, oddly, has its 850mb low well to the NW of the GFS's over the central IN/IL border. We don't want to get caught up discussing that...

[Ellinwood]

The ensemble mean does better than the OP, but there are some but's...

Last I read:

• The EGFS and EEC outperform their OP counterparts in the 168+ FHR time frame, but not necessarily in the <120hr time frame.
• No single ensemble member tends to outperform the OP. The OP beats the individuals.
• The real edge seen by the ensemble mean in the longer range is in the tendency of that mean to dampen out high SD events that are less likely to verify at 186hr.
• The OP tends to handle "unusual" (high SD events) better in the very short range than do the ensemble clusters, and I'd say that's what we have here...several clusters of ensemble solutions.

But...that is pretty dated info. As in circa 2007.

Of course there are always buts. Fact of the matter is, overall, the ensembles are better. It's inferred that the operational can handle the high SD situations better because the ensembles have to average out a variety of more-right and more-wrong solutions. I say this and reverberate most of what you have stated assuming that people who do look at the models know that that is the nature of what you get when comparing one solution to the average of many solutions.

[Ian]

...but it has a 1004mb low over N central Mississippi. Can't we just discuss it a little bit? Of course it, oddly, has its 850mb low well to the NW of the GFS's over the central IN/IL border. We don't want to get caught up discussing that...

im willing to cottonpick the best features from multiple models at this point

[Ender]

Of course there are always buts. Fact of the matter is, overall, the ensembles are better. It's inferred that the operational can handle the high SD situations better because the ensembles have to average out a variety of more-right and more-wrong solutions. I say this and reverberate most of what you have stated assuming that people who do look at the models know that that is the nature of what you get when comparing one solution to the average of many solutions.

I guess my point/worry is as stated in HPC's final EFD:

THIS SFC LOW IS FCST TO BE URGED ALONG BY A DEEP

BUT OPEN TROF ALOFT... WITH SOME MID LVL HGT ANOMALIES EXPECTED TO

REACH AT LEAST 5 STANDARD DEVIATIONS BELOW NORMAL IN THE SRN PART

OF THE TROF LATE SUN THRU MON. So...maybe this is a "but scenario".

Still, if it is, then the OP run should prevail, and, in this case, it seems that we'd want to go with the more skillful OP model (EC) that, while has shifted from W to E to W, hasn't shifted nearly as wildly as the less skillful OP run.

[kurtstack]

There appears to be a lot of discontinuity with the models at this point. I think Usedtube nailed it on the head though. We are lacking confluence, so there is nothing that prevents the storm from moving in a south to north direction when the 500 vort goes negative. I think the confusion in the models is basically related to the timing of the trough going negative and some slight shifts make a big difference as to where the surface low winds up. However, I believe with the lack of confluence the favored track here would be west of the apps, but probably not as far west as the Euro is depicting. I'm more interested in where this storm tracks because of it's effects on our storm possibilities down the road. If I recall correctly, last year two of our HECS storms last year were preceded by record breaking snows in Iowa, which ended up setting the stage for the next storm. Of course we had an active southern stream then, so take that for what it's worth.

[Quasievil]

Justin Berk posted these up on Facebook ... anyone see it?

NOAA December 8th Map Discussion about weekend Part 1:

NOAA December 8th Map Discussion about weekend Part 2:

[Ellinwood]

I guess my point/worry is as stated in HPC's final EFD:

THIS SFC LOW IS FCST TO BE URGED ALONG BY A DEEP

BUT OPEN TROF ALOFT... WITH SOME MID LVL HGT ANOMALIES EXPECTED TO

REACH AT LEAST 5 STANDARD DEVIATIONS BELOW NORMAL IN THE SRN PART

OF THE TROF LATE SUN THRU MON. So...maybe this is a "but scenario".

Still, if it is, then the OP run should prevail, and, in this case, it seems that we'd want to go with the more skillful OP model (EC) that, while has shifted from W to E to W, hasn't shifted nearly as wildly as the less skillful OP run.

The question did not pertain to what was happening with this system...

...do the ensembles of the GFS have a higher score than the OP? ...

The answer is yes. Technically, it's "yes, but."

I'm not saying which one is more likely to be correct with this system... just stating a generality.