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Dec 9th Winter Threat


ORH_wxman

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Yeah upon reflection it seems Freak was thinking of a strong coastal like Dec 92 when you flood the cp with warmth. In a situation like this , if you're on the coast and want frozen you want a weaker low allowing n drain

Rereading Noyes it appears he is solely talking about the secondary reflection

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That polar vortex up north of the Canadian/US border in the Canadian Prairies is the killer in this overall synoptic setup.  It is too far west to support a colder more out to sea, or eastern solution therefore the primary low cuts through the lakes with a weak secondary component.  This is nothing worse than a 3" snow followed by sleet, freezing rain and plain rain.

yes plain rain is much worse

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yes plain rain is much worse

 

Definitely, it looks like the secondary wave along the frontal boundary forms a decent low along the front allowing snow to redevelop over the region from the GOM.  Need to watch this secondary low developing along the front as at H5 there is a ton of energy involved with the polar vortex.  One thing is for sure, its going to get down right cold next week across the northern plains.

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If the primary were to redevelop much faster into a strong secondary, then you'd also be colder.

This is what I meant.

Yeah upon reflection it seems Freak was thinking of a strong coastal like Dec 92 when you flood the cp with warmth. In a situation like this , if you're on the coast and want frozen you want a weaker low allowing n drain

Not at all what I meant. I was thinking stronger secondary to keep stronger NE winds and keep the coastal plain colder.

Rereading Noyes it appears he is solely talking about the secondary reflection

Yeah if that's not what he was talking about than I mis-interpreted it. I thought he was talking secondary. Stronger secondary is better than a weak one. I can't imagine Noyes would write a weaker primary as being a bad thing.
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Definitely, it looks like the secondary wave along the frontal boundary forms a decent low along the front allowing snow to redevelop over the region from the GOM.  Need to watch this secondary low developing along the front as at H5 there is a ton of energy involved with the polar vortex.  One thing is for sure, its going to get down right cold next week across the northern plains.

you're going to hurt your brain. 

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This is what I meant.

Not at all what I meant. I was thinking stronger secondary to keep stronger NE winds and keep the coastal plain colder.

Yeah if that's not what he was talking about than I mis-interpreted it. I thought he was talking secondary. Stronger secondary is better than a weak one.

 

 

Only if it tracks well..you can have a stronger secondary forming near LI and that would actually make it warmer (esp for eastern areas) versus a weak strung out sfc reflection that is southeast of LI...the track matters.

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GFS actually bring the low over the Cape.

 

In any case, this will have limited deep lift and RH. The onset of snow and dryslot may be 5 hrs apart.

GFS is sort of meh though with the lift so weak. I'd rather a more solid shot of forcing and a good period of thumping. 

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Only if it tracks well..you can have a stronger secondary forming near LI and that would actually make it warmer (esp for eastern areas) versus a weak strung out sfc reflection that is southeast of LI...the track matters.

Ahh I guess that's true. I was thinking of something tracking east of BOS or over the Cape into Gulf of Maine.

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http://www.eas.slu.edu/CIPS/ANALOG/thumbnails.php?reg=EC&fhr=F120&model=GFS212&map=FZRA&sort=FINAL

 

Quite a few freezing rain events at the top of the analogue lists based off the GFS 120 hr forecast.  Something to keep an eye on.

That's a cool site. What is the algorithm behind this i.e. how does it know what patterns were similar based upon past model runs?

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That's a cool site. What is the algorithm behind this i.e. how does it know what patterns were similar based upon past model runs?

 

http://www.eas.slu.edu/CIPS/ANALOG/stats.php?reg=EC&model=GFS212&fhr=F120&flg=

 

Not sure if this is what you mean......but this is a chart detailing how it comes up with the rank of analogues.

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That's a cool site. What is the algorithm behind this i.e. how does it know what patterns were similar based upon past model runs?

 

It uses some type of pattern/anomaly correlation to rank how similar each field (height, temperature, moisture at different levels) from the model forecast is with each date in the NARR dataset.

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It uses some type of pattern/anomaly correlation to rank how similar each field (height, temperature, moisture at different levels) from the model forecast is with each date in the NARR dataset.

So what you're saying is this site displays model initializations from various years that correlate closely to the 12/04/13 120 hour GFS?

 

If so that's crazy.

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Its the CIPS analog tool...the funny thing is I used to go back and use the NARR site from like 2006-2009 before this tool came out...I'd try and think of past similar systems and look and see just how similar they were, lol. I was pretty sick. :lol:

 

 

This tool makes it way easier.

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It would be nicer if they could use the entire US pattern for CIPS because sometimes breaking into sectors seems to make it less accurate.  Right now its clueless on the SRN Plains event showing virtually no analog events that produce snow or ice in AR or OK.

 

 

I agree. They should have a CONUS option.

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GFS still has a rather meager front end on this thing. Started out pretty chilly though.

 

 

Yeah its almost like the high is so strong this run, it eats the precip shiled up before it comes in while its cold enough aloft. But I think I like that trend...rather than worry about QPF, I'll take the stronger damming. The QPF will be there.

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Yeah its almost like the high is so strong this run, it eats the precip shiled up before it comes in while its cold enough aloft. But I think I like that trend...rather than worry about QPF, I'll take the stronger damming. The QPF will be there.

Yeah the damming signal is strong which bodes well for the interior for sure. I just wonder how much dynamics will this push have. For my selfish reasons, I like to see a good front end on this thing, but the euro was definitely juicier.

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