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18z 12/24 model disco

needbiggerboat

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Ian

Ian

Posted
Posted

What in the hell does it do with the low track after 54 hours? It just sits there and pounds NYC/NJ and then decides to just go 090 and straight into the Atlantic? I gotta say for now I believe HPC is very likely onto something here.

euro did the same thing with the big runs.. a bit further south. storms last yr also did similar.. block?

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WhiteoutWX

WhiteoutWX

Posted
Posted

What in the hell does it do with the low track after 54 hours? It just sits there and pounds NYC/NJ and then decides to just go 090 and straight into the Atlantic? I gotta say for now I believe HPC is very likely onto something here.

Initialization errors would have nothing to do with how the model tracks a low 54 hrs out. Thats due to model physics i would believe.

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stormtracker

stormtracker

Posted
Posted

I know... but if you issue them now and the 00z suite says swing and miss, the NWS and such look silly

There is no way I'd issue watches now based on one set of mdels with know initialization errors and another set that's not but not backed up with support from other models. 0z is the time to do that. You are correct.

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WeatherFox

WeatherFox

Posted
Posted

i wouldn't want to touch a public forecast for this event with a fifty foot pole

Not a problem. They could first put up a Winter Storm Watch for the potential of 4-6" later tonight and go to a warning if warranted tomorrow and then just do some accumulation updates if it all fell into place later tomorrow and tomorrow night.

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brettjrob

brettjrob

Posted
Posted

I think the errors may be overstated unless I'm misunderstanding how they propogate to other countries models/Navy etc.

If the error is associated with an actual observation (or multiple observations), then it would affect all models. If it's associated with the DA routines utilized in the NCEP models, it wouldn't. I'm still not clear on which type of error they're claiming occurred at 12z.

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SnowGoose69

SnowGoose69

Posted
Posted

Well said. I fully endorse this post. I really want to know what they are seeing. I'm shocked they are so willing to just toss runs with these sort of short lead times.....especially with some ensemble support.

My concern is the Euro has many more incidents of being owned by the GFS inside 72 hours, probably AS many as it has on the GFS outside 72....I still think this storm misses simply based on ridge/trough placement but I have always been skeptical of the Euro inside 72 hours, even though its verification is good we have to realize those are over every single run of the year, that doesn't mean it handles big systems well in that range.

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jerseystorm

jerseystorm

Posted
Posted

What in the hell does it do with the low track after 54 hours? It just sits there and pounds NYC/NJ and then decides to just go 090 and straight into the Atlantic? I gotta say for now I believe HPC is very likely onto something here.

If you remember the Euro was showing this same solution a couple of days ago!

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Scarlet Pimpernel

Scarlet Pimpernel

Posted
Posted

If this isn't some whacked up run like 12z, I think watches need to be issued immediately.

While I can understand this, given a holiday weekend and travel, I don't think anyone would be jumping the gun yet. There's so much fickelness here in the guidance you cannot quite go there yet. And this is still not clear enough in the DC/mid-Atlantic area. Quite unlike the Feb. 5-6 event last winter, when there was a clear signal well in advance, and so they rightly issued watches way in advance for that one.

Now, if all or almost all the 00Z guidance comes in hugely on the side of a shellacking up and down the coast, then yes...tomorrow they should issue watches in this region. This would still be a Sunday-Monday time frame we're talking about, so that's in plenty of time.

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Vandy

Vandy

Posted
Posted

What in the hell does it do with the low track after 54 hours? It just sits there and pounds NYC/NJ and then decides to just go 090 and straight into the Atlantic? I gotta say for now I believe HPC is very likely onto something here.

It looks like the stall coincides with the development of ridging out in front of the storm between the new low and the old North Atlantic low in front.

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Clinch Leatherwood

Clinch Leatherwood

Posted
Posted

Well said. I fully endorse this post. I really want to know what they are seeing. I'm shocked they are so willing to just toss runs with these sort of short lead times.....especially with some ensemble support.

100% agree. Where is the data on which data points were bogus? Which winds were in error at what heights, which RAOBs? There's none of that. No specifics.

The 10am release said nothing about errors, it said specifically there were no signficant errors that would have impacted the 12z NAM. An hour later when the bomb is on the GFS it all started. So whatever was found passed the initial error checks.

Where is the error at 6h based on the water vapor and RUC etc. Why would the 18z NOGAPs pull back hundreds of miles. Why would the RGEM tighten up.

It makes no sense to me.

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ArtRosen

ArtRosen

Posted
Posted

Not a problem. The could first put up a Winter Storm Watch for the potential of 4-6" later tonight and go to a warning if warranted tomorrow and then just do some accumulation updates if it all fell into place later tomorrow and tomorrow night.

I think it would be a good idea to put WWA out and then, if need be, upgrade them. This has been numerous times before and I'm sure by this time tomorrow, WWA's will be out in a great deal of places. I can't see watches/warnings going out for anyone except E-LI, E-CT and parts of Eastern New England... but if models trend the way they are tonight... who knows? Boy would this be a real treat for everyone.

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Scarlet Pimpernel

Scarlet Pimpernel

Posted
Posted

Well said. I fully endorse this post. I really want to know what they are seeing. I'm shocked they are so willing to just toss runs with these sort of short lead times.....especially with some ensemble support.

Just curious, but could it be a case of being (or seeming to be) "burned" by the consistent Euro runs showing a blizzard, and they kind of jumped on that...and then suddenly it all went east? So now, being extra cautious? I sure understand the conservative approach, but I don't think at this point these indications can just be tossed out of hand.

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ARyan

ARyan

Posted
Posted

Honestly, I'm not sure. It seems to be a bit conservative in some areas, even using a 10:1 ratio, but it's the only site with model-generated snowfall graphics I'm aware of that covers the east coast.

Earl's model page does some too and they are much prettier!

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Ian

Ian

Posted
Posted

I wouldn't think so. There have even been mets on this forum debating whether or not 12z should have been thrown out either.

if the gfs is handling the southern wave right this is a believable solution.. the diff between a big hit on the coast and just offshore was always heavly tied to that. why the euro isnt seeing the same thing is truly puzzling in this range.

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winterymix

winterymix

Posted
Posted

What in the hell does it do with the low track after 54 hours? It just sits there and pounds NYC/NJ and then decides to just go 090 and straight into the Atlantic? I gotta say for now I believe HPC is very likely onto something here.

I have attached the model diagnostic discussion. It seems that HPC saw this coming and isn't buying

the large west trend.

At least not yet.

Another 12 to 18 hrs. of model watching for sure.

If I were making a public forecast, I would divide the GFS output by two thirds, knowing it

could be increased tomorrow.

MODEL DIAGNOSTIC DISCUSSION

NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD

143 PM EST FRI DEC 24 2010

VALID DEC 24/1200 UTC THRU DEC 28/0000 UTC

...SEE NOUS42 KWNO ADMNFD FOR THE STATUS OF THE UPPER AIR

INGEST...

12Z MODEL EVALUATION INCLUDING THE ECMWF AND FINAL PREFERENCES

...SPLIT SHORTWAVE TROUGHS EXTENDING OVER THE PLAINS/MIDWEST...

...LOW PRESSURE FORMING ALONG THE EAST COAST THROUGH MONDAY...

PREFERENCE: EQUAL BLEND OF THE 06Z GFS/12Z ECMWF OR THE 06Z

GEFS/00Z ECMWF ENSEMBLE MEANS

INITIALIZATION ERRORS IN NUMEROUS DIAGNOSTIC

QUANTITIES...INCLUDING HEIGHT/VORTICITY FIELDS/RH...ARE EVIDENT IN

BOTH THE 12Z NAM/GFS WITH SMALL BUT LIKELY SIGNIFICANT SHORTWAVE

TROUGHS OVER SOUTH DAKOTA/NEBRASKA ALONG WITH

SASKATCHEWAN/MANITOBA...WITH THESE AREAS ALSO NOT PARTICULARLY

RESOLVED OR PREDICTED WELL BY THE 00Z ECMWF. THUS...THE SPECIFIC

PREDICTIONS BY ALL DETERMINISTIC GUIDANCE ARE IN QUESTION...WITH

THE RECOMMENDATION TO FOLLOW CONTINUITY...WITH THE FINAL OUTCOME

MOST BELIEVED TO LIE BETWEEN THE 06Z GFS AND 00Z ECMWF...WITH ALL

ENSEMBLE GUIDANCE INCLUDING THE SREF MEAN/GEFS MEAN (EXCEPT NOT

THE 12Z VERSION)/ECMWF ENSEMBLE MEAN ALSO CONSIDERED USEFUL TO

ADDRESS THE CONTINUED UNCERTAINTY. THIS APPROACH DISREGARDS THE

SUBSTANTIALLY DEEPER AND WESTWARD SHIFT OF THE 12Z GFS REGARDING

THE POWERFUL LOW TRACKING UP THE EASTERN SEABOARD...AND TO A

LESSER EXTENT THE 12Z NAM WHICH LIES NEAR THE FAST EDGE OF THE

GUIDANCE WITH THE DEVELOPING LOW.

THE NEW UKMET/CANADIAN ARE DIFFICULT TO EVALUATE FOR

INITIALIZATION SINCE WE RECEIVE A LIMITED AMOUNT OF DATA.

HOWEVER...THEIR SOLUTIONS LIE WITHIN THE EASTERN HALF OF THE

GUIDANCE ONCE THE INDIVIDUAL TROUGHS PHASE TO PRODUCE THE

DEEPENING LOW OFFSHORE...WHICH HAS CONSISTENTLY BEEN THE CASE.

FINALLY...THE 12Z ECMWF APPEARS TO INITIALIZE REASONABLY WELL AND

TRENDS SLIGHTLY SLOWER AND EAST OF ITS PRIOR RUN OFFSHORE...AND IS

NEARLY IN PHASE WITH THE 06Z GFS UNTIL VERY LATE IN THE PERIOD

WHEN ITS BEGINS TO MERGE WITH ITS PRIOR RUN. THUS...THE FORECAST

RATIONALE HAS NOT CHANGED APPRECIABLY...WITH THE FINAL

RECOMMENDATION ONLY TO REPLACE THE 00Z ECMWF IN THE PREFERENCE

ABOVE WITH THE 12Z ECMWF...GIVING EQUAL WEIGHTING TO BOTH RUNS.

...HIGH AMPLITUDE SHORTWAVE TROUGH ENTERING THE WEST SATURDAY

NIGHT/SUNDAY...

PREFERENCE: 12Z ECMWF ACROSS CALIFORNIA AND THE SOUTHWEST

THE GFS HAS TRENDED SLOWER WITH SOUTHERN PORTIONS OF THE TROUGH

ENTERING CALIFORNIA AND THE SOUTHWEST...WHILE THE NEW ECMWF HAS

TRENDED SLIGHTLY FASTER...WHICH PLACES THE NAM NEAR THE SLOW EDGE

OF THE GUIDANCE AND THE GFS WITHIN THE FAST HALF OF THE GUIDANCE.

THUS...TO ADDRESS THE INCREASING SPREAD AND UNCERTAINTY IN

TIMING...THE RECOMMENDATION IS FOR INTERMEDIATE TIMING ACROSS THE

SOUTHWEST...WHICH IS ACTUALLY CLOSEST TO THE 12Z ECMWF.

OTHERWISE...NORTHERN PORTIONS OF THE TROUGH ARE HANDLED

COMPARABLY.

...LOW PRESSURE NEARING THE PACIFIC NORTHWEST COAST LATE MONDAY...

PREFERENCE: 1/3 EACH NAM/ECMWF/UKMET

THE NEW ECMWF HAS TRENDED SLIGHTLY SLOWER AND STRONGER...WHICH

AGREES WITH THE UKMET...AND PLACES IT NEAR THE MODEL CONSENSUS.

HOWEVER...THE NAM IS WEAKER AND MORE PROGRESSIVE THAN THE

ECMWF...WHILE THE GFS IS WEAKER LIKE THE NAM BUT PLACES THE LOW AS

MUCH AS 200 NM FARTHER SOUTH. THUS...TO ADDRESS THE SOLUTION

SPREAD WHILE DISREGARDING THE MORE EXTREME SOLUTIONS SUCH AS THE

GFS/CANADIAN...THE RECOMMENDATION IS FOR 1/3 EACH NAM/ECMWF/UKMET.

...MODEL TREND GRAPHICS AT

WWW.HPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML...

...500MB FORECASTS AT WWW.HPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML...

JAMES

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