18z 12/24 model disco

[chris87]

but it would have a negative effect on all models...

KCR is in Iowa I think, deleting that for error would be significant given the current placement.

[Guest someguy]

From PHL:

Very smart. See what 0Z has to say, and if the GFS continues this and the EURO ensembles shift west, then we wake up on Christmas morning to a Special Weather Statement or Winter Storm Watches. If it continues throughout Saturday, we awaken Sunday morning to Winter Storm Warnings (or more).

YEAH but down here in eastern and central VA we are running out of time

NWS and TV are going 1" in RIC and 2-3 in se va

if the 18z GFS is right its going to be 4-8 in central va and 8-12 is se va

and on saturday night and sunday.....

[winterymix]

And? Does that answer WHY?

HPC is the only game in town for model diagnostics.

Until someone becomes a fortune teller or until the models

improve alot, this is the end of the line for knowing WHY.

[ORH_wxman]

And? Does that answer WHY?

HPC is going to report any errors they think might be there first...its really not at the most urgent forefront to say why in their discussion. I'm sure they are looking at a ton of stuff...so getting on their case for not issuing a post-mortem on "Why" is ridiculous IMHO.

[Reale WX]

WHAT AN AMAZING DAY AND WEEK!

I've never seen anything like this before...such a difference in models so close to a storm, AFTER a flip-flop of both EURO and GFS! Try attempting to make a forecast on TV on such an important weekend.

As for meteorological stuff, we get a special product at NBC10 in Philadelphia called eCast. This is a product from AER in Mass. that creates a MOS based on the EURO ensembles. For example, it gives the POP for every 12 hour period of 01, .10. and .50. A POP of 30 means that 30% of the 51 ensemble members had more than that amount of precip during the period in question. It has had a great track record over the past several years for us.

Curiously, it has had surprisingly low POPs for PHL this week. Even when the operational EURO was hammering us 3 days in a row, the POPs for .50"+ never got over 16%. Today's POPs are 57% for .01", 22% for .10", and 2% for .50"+. That was based on the 00z run.

The eCast maps from the 12z run show the storm track very close to the operational, and precip farther west (but still less than .25" at ACY, and less than .10 at PHL.

If we have the same issues with the 00z runs, I will not be able to sleep tonight (working the 10 and 11pm tomorrow).

My mind goes back to Jan, 2000, when everyone was so sure the storm would stay way offshore. But the radar echoes were way farther west than even the 12 hour forecasts were, so I was able to predict snow up here when other forecasts were still for "partly sunny" (still had no idea we'd get so much). This has taught me to never brag about a forecast before the event, and never say never until the event is over.

Glenn

Good info thanks... glad to see in 2000 you based your forecast on obs and what was actually happening, not just bad model data

[A-L-E-X]

KCR is in Iowa I think, deleting that for error would be significant given the current placement.

Cedar Rapids? If its in Iowa it would probably affect the northern stream-- not the SW in Texas that is blowing up a ball of convection. Time will tell.

[p626808]

WHAT AN AMAZING DAY AND WEEK!

I've never seen anything like this before...such a difference in models so close to a storm, AFTER a flip-flop of both EURO and GFS! Try attempting to make a forecast on TV on such an important weekend.

As for meteorological stuff, we get a special product at NBC10 in Philadelphia called eCast. This is a product from AER in Mass. that creates a MOS based on the EURO ensembles. For example, it gives the POP for every 12 hour period of 01, .10. and .50. A POP of 30 means that 30% of the 51 ensemble members had more than that amount of precip during the period in question. It has had a great track record over the past several years for us.

Curiously, it has had surprisingly low POPs for PHL this week. Even when the operational EURO was hammering us 3 days in a row, the POPs for .50"+ never got over 16%. Today's POPs are 57% for .01", 22% for .10", and 2% for .50"+. That was based on the 00z run.

The eCast maps from the 12z run show the storm track very close to the operational, and precip farther west (but still less than .25" at ACY, and less than .10 at PHL.

If we have the same issues with the 00z runs, I will not be able to sleep tonight (working the 10 and 11pm tomorrow).

My mind goes back to Jan, 2000, when everyone was so sure the storm would stay way offshore. But the radar echoes were way farther west than even the 12 hour forecasts were, so I was able to predict snow up here when other forecasts were still for "partly sunny" (still had no idea we'd get so much). This has taught me to never brag about a forecast before the event, and never say never until the event is over.

Glenn

Well Said!

This might come down to a 1/2000 event and have to be nowcasted.

[weatherweather]

Couldnt we start comparing 12 and 18 hour maps from old runs to current conditions and get a better idea of which idea is right?

[yoda]

Howard Bernstein (WUSA9 DC MET) says he wants to see other models get on board after seeing this run

[cp63]

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.

Quite funny how the storm is predicted so similary in each models "wheelhouse"

Euro 4-8 days

Gfs 3 days and in.......

[Amped]

It's almost like predicting whether the spark will hit the TNT or pass 2mm to the left of it.

[Analog96]

HPC is going to report any errors they think might be there first...its really not at the most urgent forefront to say why in their discussion. I'm sure they are looking at a ton of stuff...so getting on their case for not issuing a post-mortem on "Why" is ridiculous IMHO.

Then you are calling dtk ridiculous too, I suppose?

[Clinch Leatherwood]

but it would have a negative effect on all models...

You'd think right? I don't get it.

I don't quite get how it's this bad when at face value it appears to match up very well with obs since then, water vapor, and RUC sampling. It may be a case where this is a joke run or two, but it would be really great to see that error appear plainly in terms of water vapor imagery etc.

What I don't get is how the initial diagnostic said nothing was wrong with the NAM, it was only after the GFS came out that problems seemed to appear.

[Analog96]

You'd think right? I don't get it.

I don't quite get how it's this bad when at face value it appears to match up very well with obs since then, water vapor, and RUC sampling. It may be a case where this is a joke run or two, but it would be really great to see that error appear plainly in terms of water vapor imagery etc.

What I don't get is how the initial diagnostic said nothing was wrong with the NAM, it was only after the GFS came out that problems seemed to appear.

Me, dtk, and you vs HPC now lol.

[SnowGoose69]

Quite funny how the storm is predicted so similary in each models "wheelhouse"

Euro 4-8 days

Gfs 3 days and in.......

If the storm ultimately happens it will be because the Euro was right for the wrong reason on its initial reasoning why it would occur...it technically will verify because of dumb luck due to its bias in the medium-long range.

[Clinch Leatherwood]

Couldnt we start comparing 12 and 18 hour maps from old runs to current conditions and get a better idea of which idea is right?

Yes you can, but the problem is the tools we have don't really refute what the NAM and GFS are showing yet.

There's a ton of pros in here, can someone use their analytic capabilities and tools to show us where the egregious errors were on the 18z 0h at 500etc?

I can't find these errors, slight sure, but that's normal. I can't find the smoking gun.

[Riptide]

18z GFS Ensemble Mean

[A-L-E-X]

FWIW 18Z GFS ensembles are a huge hit.

[isnice]

I don't understand:

It clearly said in the HPC discussion that the 12z NAM and GFS ingested bad data. They are the only two models showing a large storm (besides the SREF). The 18z runs use part of this data and are probably way off. Why are we still considering a major hit?

[SnowGoose69]

18Z GFS ensenbles = congrats Scranton???

[yoda]

[needbiggerboat]

gfs ens through 1AM monday

[atownwxwatcher]

I don't understand:

It clearly said in the HPC discussion that the 12z NAM and GFS ingested bad data. They are the only two models showing a large storm (besides the SREF). The 18z runs use part of this data and are probably way off. Why are we still considering a major hit?

Did the same bad DATA effect the 18 Z NOGAPS which shifted 200 miles west?

https://www.fnmoc.navy.mil/wxmap_cgi/dynamic/NGP/2010122418/ngp10.prp.054.namer.gif

This should be a flag to the ECM

[Guest someguy]

Fair enough than if you feel that this question makes me wrong than I will just respectfully accept it, and if it is suffice for a warn status than I will just have to live with that too. And I am a decent man to admit that, that question does look suspect for saying to someone they are wrong, so simply put.

I am sorry

OK... Thanks..... its good

merry xmas

god I hope this trend is real and on the 0z gfs

[LocoAko]

I don't understand:

It clearly said in the HPC discussion that the 12z NAM and GFS ingested bad data. They are the only two models showing a large storm (besides the SREF). The 18z runs use part of this data and are probably way off. Why are we still considering a major hit?

I'm wondering the same thing. HPC called the data out in error for a reason and I do find it suspicious that the only models showing a hit so far are the ones affiliated with the alleged "error". 00Z tonight will truly be the telling time, but I'd proceed very cautiously...

[SnowGoose69]

Did the same bad DATA effect the 18 Z NOGAPS which shifted 200 miles west?

https://www.fnmoc.na...p.054.namer.gif

This should be a flag to the ECM

I don't follow the NOGAPS enough to know if its off hour runs are as prone to bizarre solutions as the NAM/GFS often are.

[SeVa]

YEAH but down here in eastern and central VA we are running out of time

NWS and TV are going 1" in RIC and 2-3 in se va

if the 18z GFS is right its going to be 4-8 in central va and 8-12 is se va

and on saturday night and sunday.....

As much as I would love to see heavy snow, I can't imagine what would happen if we got a foot down here in se Va without sufficient warning. I mean, we have like 10 snowplows to service around 5 million people. It might be smart to shift some snow clearing assets from the western part of the state, otherwise we are ****ed

[weatherweather]

I don't understand:

It clearly said in the HPC discussion that the 12z NAM and GFS ingested bad data. They are the only two models showing a large storm (besides the SREF). The 18z runs use part of this data and are probably way off. Why are we still considering a major hit?

18z rgem major west shift too, though not like the gfs

[WildWeatherAdventure]

WHAT AN AMAZING DAY AND WEEK!

I've never seen anything like this before...such a difference in models so close to a storm, AFTER a flip-flop of both EURO and GFS! Try attempting to make a forecast on TV on such an important weekend.

As for meteorological stuff, we get a special product at NBC10 in Philadelphia called eCast. This is a product from AER in Mass. that creates a MOS based on the EURO ensembles. For example, it gives the POP for every 12 hour period of 01, .10. and .50. A POP of 30 means that 30% of the 51 ensemble members had more than that amount of precip during the period in question. It has had a great track record over the past several years for us.

Curiously, it has had surprisingly low POPs for PHL this week. Even when the operational EURO was hammering us 3 days in a row, the POPs for .50"+ never got over 16%. Today's POPs are 57% for .01", 22% for .10", and 2% for .50"+. That was based on the 00z run.

The eCast maps from the 12z run show the storm track very close to the operational, and precip farther west (but still less than .25" at ACY, and less than .10 at PHL.

If we have the same issues with the 00z runs, I will not be able to sleep tonight (working the 10 and 11pm tomorrow).

My mind goes back to Jan, 2000, when everyone was so sure the storm would stay way offshore. But the radar echoes were way farther west than even the 12 hour forecasts were, so I was able to predict snow up here when other forecasts were still for "partly sunny" (still had no idea we'd get so much). This has taught me to never brag about a forecast before the event, and never say never until the event is over.

Glenn

I'd just like to thank you Hurricane for giving the public a real explanation of what the situation is. I have watched about four newscasts now and you were the only meteorologist to mention the possibility of some real snow. You presented the storm in a clear, understandable fashion. Keep up the great work and have a merry christmas!

[A-L-E-X]

I'm wondering the same thing. HPC called the data out in error for a reason and I do find it suspicious that the only models showing a hit so far are the ones affiliated with the alleged "error". 00Z tonight will truly be the telling time, but I'd proceed very cautiously...

The good thing is the 12z euro ensembles were also west. Like you said, we should know by 0z-- or at least have a reasonable idea.