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February 7th Storm Threat Discussion/Obs


mappy
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3 minutes ago, MillvilleWx said:

I personally am not a fan of SREF's outside an envelope of potential max and min and that's about it. A lot of times, it guides the 5th and 95th percentiles, so you have a clue as to what is the most extreme result. Hi-res is so prone to minute shifts in guidance that SREF's can exacerbate and/or waver from run to run, so they really are only prudent inside 48 hrs, at least imo. HREF is the newest ensemble blend of hi-res guidance and it does a better job overall and can pick out trends, but it realllllllly struggles with ULL's and intense baroclinicity. It did pick out the potential for the banding in Binghamton with the mega bomb up there, so it's not all for naught. I think there will be more investment in hi-res ensembles down the pike, but we have a major step in Fv3 integration the next 3-4 years, so it's probably more of a side project. Someone who works directly with NWP will have more info on that. 

 

10 minutes ago, psuhoffman said:

WAY more amplified this run.  BTW we know the SREF has crazy biases but it is somewhat useful with trends just as a curiosity in between model runs.  It does tend to trend with the other guidance in general.  

@high risk @MillvilleWx do you happen to know if anyone still even looks at the SREF?  And also...the idea of a short range meso scale ensemble is a great idea imo.  The meso models are needed to pick out features the globals cannot but they are very susceptible to being jumpy which is probably unavoidable when you make them sensitive enough to pick up on meso features.  An ensemble to help eliminate that issue is a great idea...but it seemed the SREF just suffered from having members with crazy biases that skewed them.  Why wasnt there, or is there, an effort to develop a more useful short range ensemble system?  Thanks for any info.  

              The SREF was a good idea, as it mixed and matched two different model cores, initial conditions from three different systems, and different physics.    It's really, really tough to get meaningful spread in the short range, so the approach was smart, but the problem is that things were never successfully tuned.    You have 26 members, but you often get two camps, with clusters for each of the two cores.    The ARW members tend to be very amplified, and the NMMB members tend to be flat.    The middle ends up being ok-ish, but you could get the same answer with just one member from each of the two cores.      But I agree that it shows the general range of possibilities.    The SREF will be turned off once it is established that the GEFS can cover the short range, as AWC and WPC still use the SREF.

              HREF simply blends the NAM nest and the three Hi-Res Windows.    Version 3 (coming this spring) includes the HRRR too, and the Hi-Res Window NMMB member gets replaced with an FV3 member.     It's only as good as the models that comprise it, and there are shortcomings as Millville noted, but it scores quite well.    It will serve as the baseline for the new Rapid Refresh Forecast System (hi-res, 10 member, hourly FV3 ensemble) which is probably ~3 years away.     

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7 minutes ago, WinterWxLuvr said:

Funny how different people see different things when looking at data. Guess perspective is reality.

I was looking at the MSLP and it was a significant trend more amplified and slightly closer to the coast with the track.  The precip was also more expansive to the west.  But there was a reduction in the max precip stripe to the SE of 95...and there was a significant decrease is snow to the SE of 95.  Not sure why the decrease is precip given the more amplified mean on the MSLP.  Probably divergent camps.  If one camp trended more west it could explain why the reduction east of 95...there may be a camp that drops more significant precip to their west and dryslots that area.  There may have been a few members skewing the qpf way high there that are not this run.  Hard to say but those kinds of details are unreliable on the SREF.  The track was a little west and the mean slp was deeper and the precip extended further west.  Those were the main takeaways I got from it.  And that was probably too much to take from the SREF lol

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Just now, nj2va said:

I thought at 42 the shortwave looked less intense than 18z...

          That's my take too.    Definitely a weaker shortwave, which dampens the ridging out ahead.    I don't think this will be as good as the 18z NAM, although I don't *think* it will be awful either.

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1 minute ago, MillvilleWx said:

NAM has more a look comparable to 12z. 18z was more amped. This was not as intense, but very similar to 12z. Will still get the job done, but a bit SE of 18z imo

interestingly...the issue was a weaker southern vort this run...but there were some improvements in other ways...the northern stream is actually oriented more favorably imo and could even really amp this up had there not been such a weaker SW this run.  In the end the weaker SW offset the improvements in other places...but if that SW were to trend more amplified again this could really go nuts given the trend for the NS to dig and go negative sooner and further west.  

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Just now, psuhoffman said:

interestingly...the issue was a weaker southern vort this run...but there were some improvements in other ways...the northern stream is actually oriented more favorably imo and could even really amp this up had there not been such a weaker SW this run.  In the end the weaker SW offset the improvements in other places...but if that SW were to trend more amplified again this could really go nuts given the trend for the NS to dig and go negative sooner and further west.  

It's funny you say that because I was literally just looking at the 25H panels and the jet placement is actually little better than previous runs. The strength is a touch lower than 18z, but further back, so wouldn't be surprised if this still gets the job done for areas east of US15.

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1 minute ago, MillvilleWx said:

It's funny you say that because I was literally just looking at the 25H panels and the jet placement is actually little better than previous runs. The strength is a touch lower than 18z, but further back, so wouldn't be surprised if this still gets the job done for areas east of US15.

yea despite the late start and weaker SW its still trying to climb the coast.  But just looking at the whole way the jet and the NS is oriented gives me the vibe this would really amp up and go nuts up the coast if that SS SW ends up slightly more amplified.  There is a LOT of room for this to amplify up the coast looking at the flow.  The thing that could save us from too north of a trend is that it starts out pretty far SE before it begins to gain latitude.  I know it trended SE but this run didn't give me a "its getting suppressed" vibe.  If anything it furthered my opinion this is likely to amp up more as we get closer.  

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