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Potential winter threats


tombo82685

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I think that whole thing came about from dt, when he would always say because of the gfs cold bias it would push everything so far south.

Haha I think that's what I had in my mind Tom. I remember him constantly saying that.

Check out the the two penultimate boxes here: http://www.hpc.ncep.noaa.gov/mdlbias/biastext.shtml#GFS

But again, that's prior to the upgrade in July

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No worries. It's good to talk about. I sent a message to dtk. He knows more about that stuff than I do.

Honestly, some of the people on here look at things like this more closely than I do (in terms of case by case evaluation...I look mostly at bulk stats/verification until people point out specific examples to me). Having said that, I agree with your previous comment about the GFS summer upgrade, especially since the sign of the bias (temperature/height) has actually changed in some parts of the atmosphere. I haven't thought much about how this might manifest itself in terms of development (over developing versus suppressed, etc.).

We are sort of learning about specific behavior like this in real-time, since this NH winter seems to be significantly different than the test winters we ran through prior to implementation (i.e. 0809 and 0910).

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Check out the the two penultimate boxes here: http://www.hpc.ncep....stext.shtml#GFS

But again, that's prior to the upgrade in July

yea i see the one where it says prediction of southward movement of cold air overdone. Wouldn't that kind of result in a se bias of pushing storm off to far south do to its bias of bringing down the cold air to far south and to strong?

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yea i see the one where it says prediction of southward movement of cold air overdone. Wouldn't that kind of result in a se bias of pushing storm off to far south do to its bias of bringing down the cold air to far south and to strong?

Yeah. It gives conflicting signals. Either way, I'm not sure either of those are relevant anymore (at least if they are, they need to be reconfirmed, imo). The convective and radiative upgrades really made a big difference in the model.

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To me, the likely outcome based upon what the Euro is showing here is that there will be a phase between the northern and southern streams and the storm will likely come further up the coast, affecting people further north as well. The problem is that no model can depict those possibilities with much accuracy past 7 days. I believe that future runs of the Euro will start to further hone in on this possibility over the next few runs. Look at the Euro at 240 hrs if you have access to it at this period. It has what appears to be a transfer to the coast or some type of elongated trough with a precip max extending inland from Cape May, NJ to almost Buffalo, NY. My best guess is that this is an error, but it is showing the true potential of a full phase with the northern stream that would bring this storm northward from Cape Hatteras to off the NJ Coast, in similar fashion to what just happened with this last storm. The model just cannot get the details right this far out. Remember all the trouble it had getting the details correct with the last storm. It also showed a storm heading out to sea after getting to Cape Hatteras. We all know how that ended up. I expect something similar this time as well. This is my read on what the model is indicating. From HPC:

MID LEVEL BLOCKING WITH A LARGE VERY STRONG POSITIVE HT ANOMALY

RETURNS TO NERN CANADA WITH A DEEP VORTEX LOCKING IN OVER ONTARIO

AS PER 8-10 DAY ECMWF AND GFS/CMC MEANS. STRONG SRN STREAM MID

LEVEL SHORTWAVE TROF WILL SWING THRU SRN TX INDUCING LOW PRESSURE

ALONG THE GULF COAST IN A MOISTURE RICH ENVIRONMENT AND BRING AN

AREA OF LOW PRESSURE INTO THE SOUTHEAST AND UP ALONG THE SOUTHEAST

AND MID ATLC SEABOARD OVER THE NEXT WEEKEND. LONGER RANGE CMC AND

ECMWF SUPPORT THIS SCENARIO.

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???? :arrowhead:

big time threat at 192 hr, it just slides ots because of the PV sitting ontop of us like the gfs always does past 200 hrs

looks like a threat to me

I think I said " The GFS says there is no threat for any snow"

http://www.nco.ncep....fs_ten_192s.gif

http://www.nco.ncep....fs_ten_204s.gif

http://www.nco.ncep....fs_ten_216s.gif

Which the above images imply there is no threat on the 00z GFS because it slides well out to sea...

If this were coming up the coast similar to what the ECM showed i would consider it a threat but as of right now the model is saying its a no go..does not mean I am implying its correct but i also would not consider it a threat....per this model.

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I think I said " The GFS says there is no threat for any snow"

http://www.nco.ncep....fs_ten_192s.gif

http://www.nco.ncep....fs_ten_204s.gif

http://www.nco.ncep....fs_ten_216s.gif

Which the above images imply there is no threat on the 00z GFS because it slides well out to sea...

If this were coming up the coast similar to what the ECM showed i would consider it a threat but as of right now the model is saying its a no go..does not mean I am implying its correct but i also would not consider it a threat....per this model.

i guess we just have different views on the word "threat" :lmao:

because when i look at the 500mb map and Not the surface map i see a big time threat, but the gfs messes it up with usual garbage..who knows, the gfs could still have a cold/supression bias :yikes:

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i guess we just have different views on the word "threat" :lmao:

because when i look at the 500mb map and Not the surface map i see a big time threat, but the gfs messes it up with usual garbage..who knows, the gfs could still have a cold/supression bias :yikes:

The models are all over the place essentially...

Here is the GGEM at 168

http://www.meteocentre.com/models/gemglb_amer_00/P6_PN_168_0000.gif

Has a low over NE PA and another low off the coast it would appear & then later on at the next time period...

http://www.meteocentre.com/models/gemglb_amer_00/P6_PN_204_0000.gif

http://www.meteocentre.com/models/gemglb_amer_00/P6_PN_216_0000.gif

So the GFS is forming something in the south while the GGEM has more of a clipper type low moving south and then eastwards and off the coast....

To me its more about the pattern then the models and there individual solutions....

.

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The models are all over the place essentially...

Here is the GGEM at 168

http://www.meteocent...PN_168_0000.gif

Has a low over NE PA and another low off the coast it would appear & then later on at the next time period...

http://www.meteocent...PN_204_0000.gif

http://www.meteocent...PN_216_0000.gif

So the GFS is forming something in the south while the GGEM has more of a clipper type low moving south and then eastwards and off the coast....

To me its more about the pattern then the models and there individual solutions....

.

what the ggem is showing there looks almost like what the 12z euro has. Coastal low off hse that moves east while a northern stream feature tracks over the area bringing in mod precip.

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what the ggem is showing there looks almost like what the 12z euro has. Coastal low off hse that moves east while a northern stream feature tracks over the area bringing in mod precip.

Are you referencing this hour?

It is similar I think but the ECM seemed to have a more defined area of low pressure off Hatteras where the GGEM seems to be lacking that...

just using the ECM map to show the difference in a more defined low south of Hatteras..

Anyways, ECM is running and lets see what solution comes from the grab bag of models tonight..

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No, the storm before that.

Oh i was under the impression that the 12 Z ECM had a northern stream system(from Duluth) that dropped moderate to heavy precipitation from DC to NYC at the same time it had to low go off of Hatteras which would have been between 228-240 hrs..I was not aware that there was a system between 144 and 168 hrs as the maps would not imply anything from 12 Z...

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Oh i was under the impression that the 12 Z ECM had a northern stream system(from Duluth) b that dropped moderate to heavy precipitation from DC to NYC at the same time it had to low go off of Hatteras which would have been between 228-240 hrs..I was not aware that there was a system between 144 and 168 hrs as the maps would not imply anything from 12 Z...

the time frames don't match up, but the overall jist of what happens is pretty close. Euro is hr 234-240, ggem is 168-180

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