NYC/PHL 12/21-12/27 Forecast Threats

[NEG NAO]

Next frame...awesome signal on the individuals this evening

http://www.meteo.psu.edu/~gadomski/ENSPRSNE_18z/f162.gif

With all due respect we were saying the same thing about a week ago about this missed system . This go around - the worry is mixing and or changeover issues...

[earthlight]

With all due respect we were saying the same thing about a week ago about this missed system . This go around - the worry is mixing and or changeover issues...

Sure, but what happened previously doesn't take away from the fact that the signal is strong.

And the last part of your post I disagree with, I don't think the blocking as modeled will support that. Things can change though.

[Ridingtime]

With all due respect we were saying the same thing about a week ago about this missed system . This go around - the worry is mixing and or changeover issues...

No, this go around with the 12/19 18z GFS maybe that's the worry. But not with anything else, especially thanks to the ridge over the rockies, and what the other models have been forecasting, I just don't think we should be concerned about it being too west.

[SACRUS]

With all due respect we were saying the same thing about a week ago about this missed system . This go around - the worry is mixing and or changeover issues...

Im still more concerned with a further east track than one close in casuing mixing issues ala ggem/uk and previous euro runs. At this time the 12z from today euro seems the compromise.

[earthlight]

It's absolutely amazing how the GFS keeps rebuilding the block in the long term. The pattern tells us it should be highly unfavorable--but we are in a cycle where the north Atlantic blocking just won't give up. The GFS completely breaks down the block, but it only lasts a day or two before another big one builds in.

http://www.meteo.psu.edu/~gadomski/ENSHGTAVGNH_12z/f384.gif

[earthlight]

As far as this upcoming storm, this is really just an awesome look with the height field and departures at H5

[Neblizzard]

As far as this upcoming storm, this is really just an awesome look with the height field and departures at H5

I think the ridge axis out west is a bit east for my liking, but the GFS really sharpens the trof in the east hence the big storm idea....

[HSNN4]

With all due respect we were saying the same thing about a week ago about this missed system . This go around - the worry is mixing and or changeover issues...

With all due respect the models had no clue last week !!

[ace0927]

even looking at the individual members at h5, there is very little difference in each...incredible agreement this far out. Thoughts?

As far as this upcoming storm, this is really just an awesome look with the height field and departures at H5

[ace0927]

With all due respect we were saying the same thing about a week ago about this missed system . This go around - the worry is mixing and or changeover issues...

huh? because of one model run???? the h5 pattern is about as good as it gets for us....chill out.

[chubbs]

5-6 days out mixing/rain is almost always a concern. Particularly in December when the ocean is relatively warm. Only time will tell.

[Alpha5]

5-6 days out mixing/rain is almost always a concern. Particularly in December when the ocean is relatively warm. Only time will tell.

Oceans are running way below normal...I know the sound is at least

But I see your point

[Thunder Road]

With all due respect the models had no clue last week !!

I don't mean to lash out at anyone but can we please put this "the models were bad last week so they should never be trusted" argument to bed already?

Models are not perfect, and by the end of 0z Thursday suite (72-84 hours before potential storm) it was becoming rather obvious that this was a non-event.

AND next week's storm is an entirely different kind of storm and set-up, one which the models usually handle better than a coastal regeneis.

Ok sorry </rant>

I didn't mean to call you out but I can't take another one of those posts

[hudsonvalley21]

even looking at the individual members at h5, there is very little difference in each...incredible agreement this far out. Thoughts?

HPC agrees too.

EXTENDED FORECAST DISCUSSION

NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD

151 PM EST SUN DEC 19 2010

VALID 12Z WED DEC 22 2010 - 12Z SUN DEC 26 2010

...STORMY HOLIDAY WEATHER...

THE FORECAST SPREAD/SOLUTION ENVELOPE REMAINS SMALLER THAN NORMAL

AS MODELS AND ENSEMBLES AGREE QUITE WELL WITH DEVELOPMENT AND

EVOLUTION OF AN AMPLIFIED AND STEADILY PROGRESSIVE MID-LATITUDE

FLOW PATTERN FROM THE ERN PACIFIC ACROSS THE LOWER 48 OVER THE

COMING HOLIDAY WEEK. THIS STORMY PATTERN WILL BE HIGHLIGHTED BY

THE INLAND SURGE OF DYNAMIC/COOLING/DESTABILILZING SHORT RANGE ERN

PACIFIC TROUGH ENERGY ALOFT OUT FROM THE INTERMOUNTAIN

WEST/ROCKIES THU OVER/THROUGH A MID-UPPER LEVEL MEAN RIDGE

POSITION BEFORE DIGGING/AMPLIFYING SEWD ACROSS THE CENTRAL US AND

OVER THE ERN SEABOARD BY CHRISTMAS. THIS SETS THE STAGE FOR

POTENTIAL FOR A SIGNIFICANT SWATH OF WINTER PCPN ACROSS THE NATION

AND LEADS TO WELL ORGANIZED HOLIDAY WEEKEND EAST COAST WINTER

STORM CYCLOGENESIS. UPSTREAM FLOW ACROSS THE CENTRAL THEN ERN

PACIFIC BY THEN BECOMES MORE OF A MESS HOWEVER WITH INCREASING

SOLUTION SPREAD...SO FORECAST CONFIDENCE DECREASES RAPIDLY WITH

TIME THERE AND INLAND INTO THE WRN US EVEN THOUGH THE BULK OF

GUIDANCE DOES ALLOW ANOTHER POTENT MID-UPPER LEVEL TROUGH TO REACH

THE WEST COAST CHRISTMAS WEEKEND WITH A RENEWED THREAT FOR MORE

HEAVY PCPN/UNSETTLED WEATHER SLAMMING INLAND.

OVERALL...WHILE GUIDANCE DOES OFFER SOME DIFFERENCES AN OVERALL

SOLUTION CLOSE TO THAT SIMILARILY PROVIDED BY RECENT GFS/ECMWF AND

GFS/ECMWF ENSEMBLE MEANS SEEMS REASONABLE AND RUN TO RUN

CONSISTENT. THE MANUALLY ADJUSTED FINAL HPC GUIDANCE PACKAGE

MAINTAINS CLOSE CONTINUITY AFTER CONSIDERATION OF GENERALLY

SUPPORTIVE LATEST 12 UTC GUDIANCE WITH ONLY SOME MINOR TWEAKS FROM

OUR EARLIER ISSUANCE. HEAVY SENSIBLE WEATHER FOCUS IS OFTEN MORE

FICKLE AS PER IMPORTANT SMALLER SCALE DIFFERENCES AND INTERACTIONS

THAT STILL FALL WITHIN NOISE LEVELS AT MEDIUM RANGE TIME

SCALES...BUT THE FLOW REGIME CERTAINTY SUPPORTS A BUSY/STORMY

HOLIDAY PERIOD.

CISCO/SCHICHTEL

[snywx]

Maybe it will actually pay to live away from the coast with this one.. Havent been able to say that much lately.. 18z GFS is a nice lookin storm up here

[hudsonvalley21]

Maybe it will actually pay to live away from the coast with this one.. Havent been able to say that much lately.. 18z GFS is a nice lookin storm up here

Hope so. Sometimes you get that front end thump then the changeover to slop. Just hope too see some type of event instead of a fish storm like today's.

[ace0927]

thanks- i cant remember a time at 120-168 hrs out there being so much agreement between the GFS, its ensembles, the EC and its ensembles....pretty amazing stuff. even the GGEm and UKMET pretty have the features in place, they are just off a smidgen....

[Feb]

Maybe it will actually pay to live away from the coast with this one.. Havent been able to say that much lately.. 18z GFS is a nice lookin storm up here

Well a certain forecaster out of State College thinks that the heaviest snows will fall between I81 and I95 which would be great for me so congrats Pittsburgh or Atlantic City.

[SACRUS]

Oceans are running way below normal...I know the sound is at least

But I see your point

latest sst anomaly

[mitchnick]

new SREF shows a rather robust s/w at 87 hrs in the NW (its beyond its useful limit, I know)

http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/sref/21/images/sref_50h_087s.gif

[simpsonsbuff]

thanks- i cant remember a time at 120-168 hrs out there being so much agreement between the GFS, its ensembles, the EC and its ensembles....pretty amazing stuff. even the GGEm and UKMET pretty have the features in place, they are just off a smidgen....

I don't comment much, but love your optimism .

[Sundog]

I don't comment much, but love your optimism .

You used to post a lot more way back.

[SnowGoose69]

HA....there it is, I knew it would happen, the possibility of the GFS remaining consistent for 5-6 straight days is zero.

[ARyan]

I don't mean to lash out at anyone but can we please put this "the models were bad last week so they should never be trusted" argument to bed already?

Models are not perfect, and by the end of 0z Thursday suite (72-84 hours before potential storm) it was becoming rather obvious that this was a non-event.

AND next week's storm is an entirely different kind of storm and set-up, one which the models usually handle better than a coastal regeneis.

Ok sorry </rant>

I didn't mean to call you out but I can't take another one of those posts

I feel the same way. However, the patter is very similar (fast flow coming from the pacific) which causes havoc with the models. But the models weren't *that* bad. There were only a handful of good runs that would have given us an MECS, the rest were OTS. The problem was that the "good" runs were evenly mixed in with the true runs and that caused a lot of hysteria.

[gkrangers]

HA....there it is, I knew it would happen, the possibility of the GFS remaining consistent for 5-6 straight days is zero.

Maybe it'll take the low through Cleveland at 00z.

[Ji]

HA....there it is, I knew it would happen, the possibility of the GFS remaining consistent for 5-6 straight days is zero.

really? You expect any model to show the same solution 5-6 days without any slight changes?

[eduggs]

Yes, after looking at the ensemble mean it is pretty clear that this run was garbage. The ensemble mean looks very much like the previous runs and the EC.

I never think in these terms. A wrapped-up NW solution is certainly possible. If a single ensemble member shows it, much less an operational run, the solution has a statistical chance of being "right."

I think in terms of probabilities. Based on several days of models and ensembles, my application of bayes' theorem would suggest a much higher probability of an offshore than onshore solution. So in this sense the 18z GFS isn't garbage, it merely alters my assigned probabilities slightly.

[ace0927]

I don't comment much, but love your optimism .

when there is reason for optimism, im optimistic. The problem is I am a Jet fan and have been scared from years of disappointment that it starts to creep into real life stuff (and weather)

[SnowGoose69]

I never think in these terms. A wrapped-up NW solution is certainly possible. If a single ensemble member shows it, much less an operational run, the solution has a statistical chance of being "right."

I think in terms of probabilities. Based on several days of models and ensembles, my application of bayes' theorem would suggest a much higher probability of an offshore than onshore solution. So in this sense the 18z GFS isn't garbage, it merely alters my assigned probabilities slightly.

Its possible but not based on the synoptic setup shown by the 18Z GFS....the biggest problem is the positioning of the ridge out west, its likely too far east but also the overall degree of phasing and ridging pumping ahead of the system seems strange. The 12/15/89 bust was modeled similar to this early but it severely overphased, in that case though the ridge was positioned well to the west and the system had already undertaken a negative tilt back over the Oh Valley...in this case the system would have a tough time amplifying that fast given there is some confluence to the pattern.

[eduggs]

With all due respect the models had no clue last week !!

Lets not spread rumors. Cumulatively, there were about 6 bad runs in 100. And even these weren't that bad - they only seemed that way because of the sensible impacts along the coast. Collectively, the modeling did fine - especially considering the height anomalies.