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NYC/PHL: January 25-27 Potential Bomb Part 4


earthlight

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They are hugging the Gem and that really is a misstep on their part based on it's performance at this time range this winter.

I'd normally be confused since the GEM has generally been progressive this winter, but the fact there are few models that are event slightly east of the GEM lead me to believe its way too far west.

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And watch the ensembles be much further west and closer to the Euro's track.

The GFS often plays these games with different features in the jet and emphasizes the wrong piece, etc. It did atrociously with the 1/12 storm for partly that reason.

if they are further west it would be LIKELY be because of the way they are handling the kicker SW...

obviously the GGEM and EC handle it differently...In about 4 or 5 model runs (6 hour runs, so 2 more EC runs) we will have a much better idea which idea is correct)....i find it weird that the GFS has been hitting this for so long and so consistently for it to be wrong. Obviously the GFS is less than stellar, but is it possible for it to be sooooo wrong over and over again???

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They are hugging the Gem and that really is a misstep on their part based on it's performance at this time range this winter.

I'd normally be confused since the GEM has generally been progressive this winter, but the fact there are few models that are event slightly east of the GEM lead me to believe its way too far west.

DAY 3...

SOUTHEAST/APPALACHIANS...

STRONG DEEP LAYER SHORTWAVE MOVING THROUGH THE MS VALLEY WILL

TRIGGER DEVELOPMENT OF A CYCLONE IN THE GULF OF MEXICO...WHICH

MOVES NORTHEAST ACROSS THE SOUTHEAST AND TOWARDS THE MID ATLANTIC

COASTLINE. THE MODELS HAVE SHIFTED THE SFC-850 MB LOW TOWARDS THE

NORTHWEST THIS RUN...WITH THE 00Z GFS ON THE SOUTHEAST SIDE OF THE

GUIDANCE ENVELOPE AND 12Z CANADIAN GLOBAL ON THE NORTHWEST EDGE.

IN BETWEEN ARE THE 12Z ECMWF/12Z GEFS MEAN/00Z CANADIAN

GLOBAL...WHICH FORM A CLUSTER OF SOLUTIONS. THE 09Z SREF MEAN

MIMICKED THE PRIOR 06Z NAM/GFS RUNS...SO WAS GIVEN LITTLE

WEIGHT...LIKE THE 12 GFS.

THE SYSTEM WILL TAP GULF AND ATLANTIC MOISTURE...WITH EXPANDING

PRECIPITATION COVERAGE WITHIN THE 850-700 MB DEFORMATION ZONE AS

THE LOW INTENSIFIES. A MIXED PRECIP TYPE EVENT IS POSSIBLE IN THE

APPALACHIANS...WITH THE 12Z CANADIAN/UKMET SHOWING ABV FREEZING

TEMPS AT 850 MB LEADING TO A POSSIBLE PERIOD OF FREEZING

RAIN/SLEET. THE ECMWF SHOWS COOLING AS THE LOW INTENSIFIES...SO

PRECIP MAY CHANGE BACK TO SNOW. A MODERATE RISK WAS SHOWN DUE TO

THE COMBINATION OF THE LIQUID EQUIVALENT UNCERTAINTY PLUS THE

PRECIP TYPE UNCERTAINTY. ADDITIONAL UNCERTAINTY EXISTS AS THE

ECMWF EXTENDS THE SHIELD OF PRECIP FASTER TO THE NORTHEAST THAN

THE 12Z UKMET/12Z NAM/15Z SREF MEAN/12Z GFS.

THE PROBABILITY OF SIGNIFICANT ICING IS LESS THAN 10 PERCENT.

PETERSEN

Á

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Well, this is interesting...

prb_24hsnow_ge01_2011012400f072_sm.gif

Very interesting. I think they are just going with "too much uncertainty" at this time. They are worried about temps east of I95, and they don't know how much precip will make it west of I95. So, that is why the low risk of 4" snows is where it is I guess.

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The far inland members are skewing that. The majority of the members are well east of the Mean. Someone pointed out earlier that using means are not efficient as they are skewed by extreme results. It matters how many members agree with the Mean and in the case of the GEM barely any do and it has been like that for days.

No actually, if the means are more west..which is a smoothed down version of the members then that would indicate that there are probably more members west then there are east...and in fact..it could very well likely be the east members are skewing the means....

http://www.weatheroffice.gc.ca/ensemble/charts_e.html?Hour=84&Day=0&RunTime=12&Type=pnm

11 of the 20 members are more NW/W or N at 84 hrs

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Posted is the 72 hr. JMA which then takes this on a path exactly like the Euro taking this to the Benchmark at sub 988mb at 96 hrs. which I have from a pay site (StormVista)

Precip shield is massive in both scope and quantity like the Euro. with a max qpf of 2.0 around Philly and 1.0-2.0 for everyone else all the way back to Altoona, down to DC and up to Maine. Hard to tell with the 24 hr jump who gets how much snow, but at 96 hrs the 0 850 line is WAY off shore and at 72 hrs it was through central NJ.

post-1914-0-00506500-1295821771.gif

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12z EURO snow liquid equivalent (FWIW) *remember only outputs .1" and then 1" and by the inch from there. I won't bother with .1" line

the 1" for snow equivalent runs

west side from Willow Grove, PA northwest to Hazleton, PA turning northeast to just south of Albany, NY into VT in the Green Mountain National Forrest

east side from Willow Grove, PA to Ewing, NJ to Hazlet NJ, soming on shore on LI at Bayshore northeast to Rocky Point LI

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12z EURO snow liquid equivalent (FWIW) *remember only outputs .1" and then 1" and by the inch from there. I won't bother with .1" line

the 1" for snow equivalent runs

west side from Willow Grove, PA northwest to Hazleton, PA turning northeast to just south of Albany, NY into VT in the Green Mountain National Forrest

east side from Willow Grover, PA to Ewing, NJ to Hazlet NJ, soming on shore on LI at Bayshore northeast to Rocky Point LI

Yeah I posted about this earlier...I'm not totally sure what the map is made to represent. First of all it's hard to believe the storm gives everyone north of PHL an inch of liquid as snow...and also, the scale goes up to some ridiculous number like 18"...I can't imagine 18 inches of liquid equivalent snowfall.

To be honest you probably know more about the maps than me, but if the map really does jump from .1" to 1" on the scale that makes it pretty much useless.

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We have 2 distinct camps, the American with the kicker pushing the storm out to sea and the rest of the world much closer or even right on the coast. This is going to be interesting to see which solution is right. I would hate to be a pro and have to hang my hat on any one solution. Do any pros have any thoughts on what type of forecast you would make at this stage of the game.?

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looking at the UKMET, the JMA, the Canadian, and the Euro. They are all focusing on the low pressure area over the inland SE while the NAM and GFS are suffering from feedback issues in the Gulf which for some reason unknown to me is causing the models to then head to the SE coast with a not well defined low pressure area, instead of the well defined one on the Euro, JMA, Canadian, and now UKMET.

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Yeah I posted about this earlier...I'm not totally sure what the map is made to represent. First of all it's hard to believe the storm gives everyone north of PHL an inch of liquid as snow...and also, the scale goes up to some ridiculous number like 18"...I can't imagine 18 inches of liquid equivalent snowfall.

To be honest you probably know more about the maps than me, but if the map really does jump from .1" to 1" on the scale that makes it pretty much useless.

Accu pro years ago had the maps of snowfall at 10:1 ratios for NAM and GFS, at some point I think about 2 years ago the way the data came changed, and they only got liquid equivalent info even tho the scales were still set for the 10:1, they changed their programing for the NAM and GFS at some point to compensate for this, GFS is sat at 10:1 and NAM you have to select between the different ratios. It appears to me that this is what is going on with their EURO snow map, they are only getting liquid equivalent and have not created the ratio system for it yet. They've only had qpf info for the EURO I think since summer so it probably hasn't been fixed yet. but if you compare the total precip map and compensate for warming that is what this has to be.

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Wow, every single member is LESS amplified than the op

Ugh...I mean I have to think the 18z GFS is doing its usual SE bias, but do any meteorologists here actually believe this storm could be a miss?

The kicker is really preventing the closed low from amplifying up the coast, seems to be very progressive on the 6z/18z GFS.

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Ugh...I mean I have to think the 18z GFS is doing its usual SE bias, but do any meteorologists here actually believe this storm could be a miss?

The kicker is really preventing the closed low from amplifying up the coast, seems to be very progressive on the 6z/18z GFS.

I think the evidence is overwhelming that something will be coming up the coast. For now, I'm treating this as an outlier.

Of course, it's weather, there is obviously some non-zero probability that it ends up well OTS.

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