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NYC/PHL Dec 26-27 Potential - Part 4

am19psu

By am19psu,
in New York City Metro

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Zir0b

Zir0b

Posted
Posted

GGEM still drives the s/w into the deep gulf laugh.gif

NAM/GFS/RGEM don't do this so I would throw this run out. Not sure why it's doing that. But the positive thing to take away from this run is the stronger and deeper northern stream energy as it dives down the trough...which has been a trend among all models tonight. 0z Euro will be telling.

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RutgersWx92

RutgersWx92

Posted
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:axe: :axe: :axe:

Horrible news. I'm starting to think this GFS op run was just a fluke run now.

The GFS ensembles have been all over the place recently and haven't been good predictors of what the next OP run is going to do, so I wouldn't worry about it too much. If the 0z Euro doesn't improve then it might be time to get concerned...

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jm1220

jm1220

Posted
Posted

and last night at 00z they where a big hit........

The data now is properly sampled, and the data then wasn't. Overall I like the trends the models seem to be showing in digging the trough deeper/slower, but I'm not sure it'll be enough for us to cash in like SNE would from a slight change. We need more of a change than they do. Maybe enough for a few or several inches on the NJ coast and Long Island, but the main heavy snow stays east. Boston on SE gets the heavy snow accums. That's really my bet at this juncture. A lot needs to go right, and it seems that one piece of a hundred interfering will cause the whole setup to collapse.

I'll definitely be awaiting the Euro, but I'm not expecting any miracles at this point.

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Snow_Miser

Snow_Miser

Posted
Posted

The GFS ensembles have been all over the place recently and haven't been good predictors of what the OP run is going to do, so I wouldn't worry about it too much. If the 0z Euro doesn't improve then it might be time to get concerned...

Agreed. When the GEFS doesn't agree with the Operational model is being either on top of, or west of the Operational model. If it agrees with the Op. it is usually E.

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SnowGoose69

SnowGoose69

Posted
Posted

Agreed. When the GEFS doesn't agree with the Operational model is being either on top of, or west of the Operational model. If it agrees with the Op. it is usually E.

GFS aside, until the GEM which has been the best model overall the last 2 events starts becoming a hit I won't feel excited over anything, unless the Euro came in with a monster hit tonight.

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jm1220

jm1220

Posted
Posted

The GFS ensembles have been all over the place recently and haven't been good predictors of what the next OP run is going to do, so I wouldn't worry about it too much. If the 0z Euro doesn't improve then it might be time to get concerned...

You would think they'd be more reliable now with better data to work with. Whatever, it's not a huge deal to get worked up on and for all I know, at 6/12z they could come west. There's still time for an adjustment but the window is closing, and as I mentioned we need a very good upper air solution to really be in this. Could be a situation where I get 8" here in Long Beach and Rutgers gets 2-3", or Montauk gets 10" and I get 1-3" tops. These sharp cutoff storms are always worrisome as well. I'd be happy if I were in Boston though, that's for sure. It could be their at least partial revenge for 2/25 last year. 21" in Central Park and all rain at Logan=OUCH.

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eduggs

eduggs

Posted
Posted

I don't even bother looking at the GEFS. At 6Z this morning they were west of the Operational model, and the Operational model actually shifted east. They are usually E of the Operational model when they agree with it.

An ensemble mean is not comparable to an operational run. Its behavior is independent of the OP. What it provides is an idea of the range of possible outcomes, and their relative likelihoods. If you re-sampled the atmosphere and re-ran the model every hour, you might get a series of solutions that resemble an ensemble population.

The OP run is clearly better than any of the individual ensembles, but having such a terrible mean this cycle suggests few if any individual members with good hits. And that's not good at all.:thumbsdown:

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eduggs

eduggs

Posted
Posted

It seems at least with regards to the GFS the ensemble mean has been trending opposite its OP run. Could it be becaus of the much weaker resolution the ensembles still haven't quite caught on to all the players properly?

Ensemble variance is pretty random. I would guess in certain contexts - especially anomalous environments - the individual members might show a particular bias. But this would be contrary to the purpose of ensemble modeling.

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goldstar

goldstar

Posted
Posted

It seems at least with regards to the GFS the ensemble mean has been trending opposite its OP run. Could it be becaus of the much weaker resolution the ensembles still haven't quite caught on to all the players properly?

Based on my newfound understanding, the ensembles calculate small changes or errors, so it would make sense in a thread the needle situation for variations of the imputs to creat the OTS solutions. Since we have figured out that any imperfection in the timing slides this thing OTS, the ensemble, in sampling all the reruns with the slightly different data, would come back OTS or way OTS.

Someone correct me if I am way off!

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goldstar

goldstar

Posted
Posted

It seems at least with regards to the GFS the ensemble mean has been trending opposite its OP run. Could it be becaus of the much weaker resolution the ensembles still haven't quite caught on to all the players properly?

Based on my newfound understanding, the ensembles calculate small changes or errors, so it would make sense in a thread the needle situation for variations of the imputs to creat the OTS solutions. Since we have figured out that any imperfection in the timing slides this thing OTS, the ensemble, in sampling all the reruns with the slightly different data, would come back OTS or way OTS.

Someone correct me if I am way off!

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NittanyWx

NittanyWx

Posted
Posted

I completely agree with this, but you and I both know our clients still aren't going to be happy with us sending out 4" for LGA and 2" for PHL and they end up with 0 (if they end up with 0).

You're not kidding about that one. I fully expect to spend the entire day on the phone tomorrow.

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atownwxwatcher

atownwxwatcher

Posted
Posted

TRIO OF SHORTWAVES PHASING INTO AN UPPER LOW ACROSS THE CENTRALAPPALACHIANS SUNDAY MORNING...LOW PRESSURE AREA STRENGTHENING OFFSHORE THE EASTCOAST...PREFERENCE FOR AN 18Z GFS/12Z ECMWF COMPROMISEINITIALLY...THE NAM HAS TRENDED SLOWER WITH THE SYSTEM MOVING OUTOF THE SOUTHWEST AND STRONGER WITH THE PIECE OF ENERGY MOVINGTHROUGH THE MIDWEST OVER ITS PAST DAY OF RUNS. ONSATURDAY/SUNDAY...THE NAM HAS TRENDED STRONGER ALOFT WITH THE MAINUPPER CENTER BUT BROADER OVERALL WITH THE TROUGH. THE NAM SURFACELOW LIES IN THE MIDDLE OF ITS PAST DAY OF RUNS TRACK-WISE...THOUGHIT IS FARTHER WEST THAN ITS 12Z OR 18Z RUNS. THE GFS HAS TRENDEDSOUTHWEST/SLOWER WITH THIS SYSTEM OVER ITS PAST DAY OF RUNS. THEECMWF HAS TRENDED QUICKER WITH THE SOUTHERN STREAM SHORTWAVE...BUTSTRONGER/FARTHER SOUTH/MORE PHASED WITH ENERGY MOVING THROUGH THEMIDWEST/ONTARIO/GREAT LAKES OVER ITS PAST COUPLE DAYS OF RUNS. THERE IS A LONG TERM MULTI-DAY WAVER SEEN IN THE ECMWF SURFACELOW...AS ITS SURFACE LOW HAS TRENDED QUICKER/WEAKER OVER ITS PASTCOUPLE DAYS OF RUNS...THOUGH IT IS SWINGING BACK TOWARDS ITSSOLUTION FROM SUNDAY.WITH THE SOUTHERN STREAM ENERGY...THE 12Z CANADIAN IN ON THE SLOWSIDE OF THE GUIDANCE AND ENDS UP WITH A CLOSED SYSTEM ALOFT LATESATURDAY IN THE GULF OF MEXICO. CONSIDERING THE FLOW UNDER THEBASE OF THE CONSOLIDATED UPPER LOW IN THE GREAT LAKES...A QUICKERSOLUTION SHOULD VERIFY BETTER...SO WILL RULE OUT THE 00Z CANADIAN. THE 00Z NAM HAS TWO CENTERS WITHIN THE MAIN UPPER CYCLONE EARLYMONDAY WHILE THE 18Z GFS/12Z ECMWF/18Z GEFS MEAN/12Z ECMWFENSEMBLE MEAN HAVE ONE CENTER OFFSHORE MAINE AT THAT TIME. OVERALL...THE 00Z GFS LOOKS TOO SLOW/SOUTHWEST WITH ITS CYCLONENEAR THE EAST COAST AS IT HAS THE SUPPORT OF ABOUT ONE-FIFTH OFTHE 18Z GEFS MEMBERS AND 1/30 OF THE 12Z GLOBAL ENSEMBLEGUIDANCE...SO IT COULD NOT BE USED HERE. THE 12Z UKMET HAS THESYSTEM OPEN AND MORE COASTAL ALOFT WHILE THE 12Z CANADIAN IS OPENBUT WEAKER WITH ANY ENERGY OFFSHORE NEW ENGLAND. AT THESURFACE...THE 12Z CANADIAN SWINGS THE LOW THE MOSTOFFSHORE...WHILE THE 00Z NAM/12Z UKMET SHOW AN INTERMEDIATESOLUTION...AND THE 18Z GFS/12Z ECMWF ARE THE FARTHEST WEST. BOTHTHE 18Z GEFS MEAN AND 12Z ECMWF ENSEMBLE MEAN FAVOR A MOREWESTERLY SOLUTION AT THE SURFACE AND SHOW GOOD AGREEMENT WITH THEGFS/ECMWF ALOFT...THOUGH THE MEANS ARE QUICKER THAN THE 18Z GFS. TO ACCOUNT FOR THE UNCERTAINTY...A COMPROMISE OF THE 18Z GFS/12ZECMWF WILL BE PREFERRED HERE WHICH SWINGS THE CYCLONE JUSTSOUTHEAST OF THE 40N 70W BENCHMARK...WHICH IS SIMILAR TO THE HPCMEDIUM RANGE PRESSURES FROM SUNDAY AND MONDAY THOUGH ABOUT 200MILES SLOWER/SOUTHWEST.

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