NYC/PHL December 24-27 Potential - Part 2

[tombo82685]

21z SREFs are out and I don't see much change from 15z, except the ridge axis is a little farther west.

to me it seems a little slower, it also seems like the 50/50 low is more in play on the 21z srefs flattening the flow a little on the east coast

[Snow_Miser]

Yeah, I think there will be a coastal and I think SNE is going to get pounded, i'm just questioning how much south of NYC gets. If I get to use old models, I actually like the 21/0z ECM the best.

I think that it is definite that places in between Philly and NYC see at least three inches.

[Snow_Miser]

The NWS offices have a number of great discussions this evening ("must read" IMO) that highlight the significant uncertainty that still exists.

For example, BOX explains:

GFS AND ITS ENSEMBLES REMAINS CONSISTENT WITH PAST FEW RUNS IN

WHIZZING THE STORM OUT TO SEA QUICKLY...GIVING US A SHOT OF SNOW

SATURDAY NIGHT INTO SUNDAY. GFS DID NOT HAVE THE BEST TRACK RECORD

HOWEVER WITH THIS PREVIOUS STORM AND ALL OF THE SNOW ON CAPE COD

YESTERDAY.

THE CANADIAN GGEM HAS BY FAR THE MOST PROLIFIC PRECIPITATION

AMOUNTS. ITS SURFACE LOW DEEPENS TO 977 MB SOUTH OF THE EASTERN

TIP OF LONG ISLAND. HEAVY SNOW WOULD BREAK OUT ACROSS ALL OF

SOUTHERN NEW ENGLAND ON THE FRONT END...FOLLOWED BY A CHANCE TO

RAIN IN THE EASTERN THIRD OR HALF OF THE AREA WITH THIS SCENARIO

AND WARMING ABOVE 0C SUNDAY NIGHT. WELL OVER A FOOT OF SNOW WOULD

OCCUR ON THE FRONT END. EASY TO GET EXCITED ABOUT THIS...EXCEPT

THAT IRONICALLY ALL OF THE GGEM ENSEMBLE MEMBERS ARE WELL TO THE

EAST...MORE IN LINE WITH THE GFS...THAN THE OPERATIONAL GGEM RUN.

THE 12Z ECMWF IS ALSO VERY IMPRESSIVE...WITH A LOW BOMBING TO 963 MB

OFF THE IMMEDIATE NEW JERSEY COAST...AND MUCH SLOWER THAN THE

OTHER MODELS WITH NO PRECIPITATION HERE UNTIL SUNDAY NIGHT. IT TOO

WOULD GIVE A DUMPING OF SNOW ON THE FRONT END FOLLOWED BY A CHANGE

TO RAIN IN THE EASTERN PART OF THE AREA. ITS TWIST IS THAT THE

UPPER AND SURFACE LOWS THEN SLIDE EAST TO EXACTLY THE BENCHMARK OF

40N 70W CAUSING ANY RAIN TO CHANGE BACK TO SNOW MONDAY THROUGH

MONDAY NIGHT. IT IS THE WESTERNMOST OUTLIER AT THE MOMENT. WILL

HAVE TO MONITOR ITS TRENDS.

OKX states:

WEAK RIDGING ACROSS THE AREA FRIDAY NIGHT INTO SATURDAY MORNING.

MODELS STILL IN GENERAL AGREEMENT WITH A COASTAL LOW PRESSURE MOVING

UP THE EASTERN SEABOARD FOR THE CHRISTMAS WEEKEND. AT THIS TIME THE

EXACT EVOLUTION INCLUDING TIMING AND TRACK DETAILS OF THE STORM

SYSTEM REMAIN UNCERTAIN. THE GFS CONTINUES TO FLIP FLOP FROM PREVIOUS

RUNS. THE 12Z/GFS IS NOW FASTER...LESS AMPLIFIED AND OUTSIDE OF THE

70/40 BENCHMARK. THE 12Z/ECMWF...ALTHOUGH STILL INSIDE THE 70/40

BENCHMARK...IS MUCH SLOWER BRINGING PRECIP INTO THE AREA SUNDAY

NIGHT INTO MONDAY AFTERNOON TIMEFRAME.

PRECIPITATION...ATTM IT APPEARS THAT THE LOW WILL TRACK CLOSE ENOUGH

TO BRING PRECIP TO THE LOCAL AREA BUT ANY SHIFTS IN THE TRACK OF THE

COASTAL LOW WILL PRODUCE SIGNIFICANT CHANGES TO POTENTIAL SNOWFALL

AMOUNTS.

PHI adds:

SOME OF THE MODEL GUIDANCE HAS COME INTO BETTER AGREEMENT, BUT

THERE REMAINS ENOUGH OF A SPREAD AND AT DAY 5, THIS STILL REMAINS

A LOWER THAN AVERAGE CONFIDENCE FCST.

ONE TREND THAT HAS DEVELOPED IS THAT VIRTUALLY ALL OF THE

GUIDANCE, WITH THE EXCEPTION OF THE GFS HAS TRENDED SLOWER WITH

THE UPCOMING STORM. AS A RESULT, CHRISTMAS DAY NOW LOOKS DRY,

DEPENDING ON THE ULTIMATE TIMING, SATURDAY NIGHT COULD END UP

MOSTLY DRY AS WELL.

VIRTUALLY ALL OF THE MDLS WANT TO BRING AT LEAST SOME PRECIP TO

THE AREA DURG THE SUNDAY INTO MONDAY TIME FRAME. THE MAIN

QUESTIONS REMAIN THE TIMING ULTIMATE PATH OF THE STORM WHICH WILL

AFFECT PRECIP AMTS (AND PSBLY PRECIP TYPE AS WELL).

THE 12Z GFS HAS A MUCH WEAKER SFC LOW, VIRTUALLY NO WELL DEFINED

VORT AND AS A RESULT IS MUCH MORE PROGRESSIVE WITH THE H5 PATN AND

KEEPS A MUCH WKR SFC LOW WELL TO OUR S AND E. THE 12Z GFS SOLN IS

AS CLOSE TO A NON-EVENT AS THE MDLS ARE SHOWING ATTM. HOWEVER, THE

GFS IS THE OUTLIER AND IS BEING DISCOUNTED ATTM.

THE 12Z UKMET HAS STUCK TO ITS GUNS ONCE AGAIN WITH A MORE ELY

SOLN, EVEN THOUGH IT HAS TRENDED WWD WITH ITS LATEST CYCLE. ITS

POSN AT 27/12Z IS WELL OFF THE NC CST. THE UKMET TENDS TO BE ONE

OF THE MORE RELIABLE MDLS, SO WHILE IT IS AN OUTLIER WITH THE

LATEST MDL CYCLE, IT REMAINS TO BE SEEN IF IT WILL CONTINUE TO BE

SO.

THE LATEST CMC HAS TRENDED A BIT SLOWER AND FURTHER E AT 12Z,

AFTER A MARKED WWD SHIFT LAST NIGHT. ON THE OTHER HAND, THE 12Z

ECMWF HAS TRENDED SLOWER BUT FURTHER W. BOTH THE CMC AND ECMWF

SOLNS WOULD BE A MORE SIGNIFICANT EVENT FOR THE REGION, WITH THE

ECMWF POSN ULTIMATELY BRINGING PRECIP TYPE INTO QUESTION

ESPECIALLY FOR SRN AND ERN SECTIONS.

THE LATEST NAEFS STILL INDICATES MORE OF A GLANCING BLOW FOR THE

REGION, WITH THE INDIVIDUAL MEMBERS PRESENTING ALL DIFFERENT

SCENARIOS.

SO, WHAT DOES THIS ALL MEAN? WELL, UNCERTAINTY PREVAILS, AS IT

SHOULD AT DAY 5, BUT INDICATIONS ARE THAT AT LEAST SOMETHING WILL

OCCUR IN THE SUNDAY/MONDAY TIME FRAME. AGAIN, THE UKMET WOULD AND

GFS WOULD INDICATE THE MOST MINIMAL EVENTS WITH THE CMC AND ECMWF

BEING MORE SIGNIFICANT. THE ULTIMATE TIMING, TRACK AND INTENSITY

OF THE LOW DETERMINE WHAT OCCURS AND THOSE DETAILS WILL HOPEFULLY

BE REFINED BY THE MDLS IN THE COMING DAYS. MDL POSNS VARY EXCEPT

FOR THE CMC AND ECMWF, WHERE THERE ARE TIMING DIFFS

LWX explains:

LOW PRESSURE IN THE SOUTHERN BRANCH OF THE JET WILL TRACK THROUGH

THE DEEP SOUTH FRIDAY NIGHT AND EVENTUALLY OFF THE SOUTHEAST COAST

SATURDAY. AT THE SAME TIME...ENERGY FROM THE NORTHERN BRANCH OF THE

JET WILL BE DIVING SOUTHEAST INTO THIS SYSTEM. AS THE TWO SYSTEMS

PHASE TOGETHER...LOW PRESSURE IS EXPECTED TO STRENGTHEN AS IT TRACKS

UP THE MID-ATLANTIC COAST SATURDAY AND TOWARD NEW ENGLAND SUNDAY.

THERE REMAINS A GOOD DEAL OF UNCERTAINTY WITH THE TRACK...TIMING AND

INTENSITY OF THE SYSTEM. IF THE LOW INTENSIFIES QUICKLY AND REMAINS

CLOSE TO THE COAST...THEN A SIGNIFICANT SNOW IS POSSIBLE ACROSS THE

AREA DURING THE HOLIDAY WEEKEND. IF THE LOW IS WEAKER AND FURTHER

AWAY FROM THE COAST...THEN SNOWFALL AMOUNTS WILL BE LIGHT. THE BEST

TIMING FOR SNOWFALL AS OF NOW APPEARS TO BE SATURDAY INTO SUNDAY.

.

Excellent discussion! Like I said, I believe a consensus will form once the s/w moves onto the PAC coast.

[Snow_Miser]

FYI... while not worth very much as discussed earlier, JMA has come west.

Shows a nice snowstorm for the Northern Mid Atl./NE.

[_AR_]

21z SREFs are out and I don't see much change from 15z, except the ridge axis is a little farther west.

lol we are already talking about differences between the 15z and 21z srefs? wow this storm must be closer than I think.

I hope we get something back this way, LV.

[Quakertown needs snow]

It's been a long time but I figure a post here and there is not a bad thing.

From my internal update from earlier this afternoon.

Playing it conservative for now.

Glad your posting, welcome back

[LVblizzard]

18z UKMET has a closed 500 low entering Texas, FWIW. Image is posted in the 18z model thread. So it seems like it's the US against the world with this storm...GFS has nothing, while UKMET, GGEM, and Euro all show a MECS/HECS or something very close.

[blizzardof09]

18z UKMET has a closed 500 low entering Texas, FWIW. Image is posted in the 18z model thread. So it seems like it's the US against the world with this storm...GFS has nothing, while UKMET, GGEM, and Euro all show a MECS/HECS or something very close.

yea the gfs is really on its own in its own world. i think the euro is gonna nail this storm its been consistent and hasnt wavered very much if any, it boggles my mind how our gfs is inferior to the european models lol

[_AR_]

18z UKMET has a closed 500 low entering Texas, FWIW. Image is posted in the 18z model thread. So it seems like it's the US against the world with this storm...GFS has nothing, while UKMET, GGEM, and Euro all show a MECS/HECS or something very close.

I can't find the storm on the FIM.

[tombo82685]

through 18 nam looks slower and deeper with the s/w

[_AR_]

CFS gives everyone a few inches:

[Snow_Miser]

I can't find the storm on the FIM.

FIM is a really junky model that might beat the DGEX, NOGAPS, CRAS and JMA in terms of model cruddiness. Don't even bother checking it out.

[eduggs]

18z UKMET has a closed 500 low entering Texas, FWIW. Image is posted in the 18z model thread. So it seems like it's the US against the world with this storm...GFS has nothing, while UKMET, GGEM, and Euro all show a MECS/HECS or something very close.

The difference between a "closed" and "open" h5 low is often just a few decameters in height. A closed contour at a particular height level doesn't guarantee a powerful wave. But the 72hr UK chart does look decent.

[tombo82685]

through 39 the nam is holding onto the closed longer than 18z nam...looks a little slower...confluence looks alittle slower but that could be the result of a little slower.

[Snow_Miser]

The difference between a "closed" and "open" h5 low is often just a few decameters in height. A closed contour at a particular height level doesn't guarantee a powerful wave. But the 72hr UK chart does look decent.

When the Ukie should that 967 mb Low P. sitting off of Hatteras, it was so suspensful! lol

[NortheastPAWx]

through 39 the nam is holding onto the closed longer than 18z nam...looks a little slower...confluence looks alittle slower but that could be the result of a little slower.

Sounds good so far...location?

[Snow_Miser]

through 39 the nam is holding onto the closed longer than 18z nam...looks a little slower...confluence looks alittle slower but that could be the result of a little slower.

NAM has been constantly shifting the time that the s/w reaches the PAC coast by around 6 hrs. so I am pretty confident that this isn't a trend, although the NAM looks good so far...

[tombo82685]

one thing i see is it looks like the confluence is stornger over the northeast

[NortheastPAWx]

one thing i see is it looks like the confluence is stornger over the northeast

That OTOH doesn't sound good.

[SteveB]

CRAS has the making of a monster:

[ravensrule]

CRAS has the making of a monster:

When you start pulling out the Crap we have problems .

[Snow_Miser]

CRAS has the making of a monster:

CRAS usually has excellent eye-candy, but usually it is inaccurate. To see it shift, as well as the JMA to the consensus is slightly encouraging.

This would be a gigantic monster, like you said, perhaps resembling the 12Z GGEM and/or ECMWF.

[SteveB]

When you start pulling out the Crap we have problems .

CRAS nailed the back-to-back early Feb 2010 storms in it's longer range fwiw. I never trust it's isotherms nor it's thicknesses much but I like to analyze the 500mb maps for comparison purposes quite a bit.

[Snow_Miser]

When you start pulling out the Crap we have problems .

CRAS is pretty crass, do you agree?

[ravensrule]

CRAS nailed the back-to-back early Feb 2010 storms in it's longer range fwiw. I never trust it's isotherms nor it's thicknesses much but I like to analyze the 500mb maps for comparison purposes quite a bit.

That may be, but how many times has it showed a great storm and we got squat.

[Snow_Miser]

Vorticy is pretty strong with the s/w similar to the 12Z Euro.

[ravensrule]

CRAS is pretty crass, do you agree?

Totally, the Crap is usually the model people pull out when every other model goes bad.

[SteveB]

That may be, but how many times has it showed a great storm and we got squat.

At least a few thousand.

[tombo82685]

this is deff trending towards the euro in terms of how slow this is....though its not closed off like the euro has it. Also, the confluence is stronger still so thats an eeee

[ravensrule]

At least a few thousand.

Exactly .