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December Med/Long Range Discussion


WinterWxLuvr

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2 minutes ago, Bob Chill said:

It's a long ways out but worth discussing a little. One of the ways we can get snow after the first big cold front is good spacing and placement with the next wave. D10 euro last night looks pretty good for either front end or even possibly getting an underneath track with the 50/50 in place. 1030+ HP right over top of the vort tracking in the middle of the country with confluence in the east instead of ridging:


<snip>

Don't do it to yourself, Bob. The Euro is going to fold to the CanSIPS.

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3 minutes ago, mattie g said:

Don't do it to yourself, Bob. The Euro is going to fold to the CanSIPS.

Yea, I'm a bit shook up with the cansips. Cancelling winter on Dec 1st is tradition that should never be discounted. 

We'll probably go through the typical "carving" of the trough/baroclinic zone and get things just right after a couple fronts and watch our first nice setup go to complete waste. Then rinse repeat until 60* on Xmans. 

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tail end cold load is legit looking.  

 

So many pieces moving around on these runs.  Only thing that looks stable for the whole run is the Bearing Sea ridge.  That helps keep some of the PV over on our side the next couple weeks.  W Canada certainly won't be torching

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2 minutes ago, Bob Chill said:

Euro op spat out another decent look after the big front. Very different than the GFS quick ridge. My guess is the eps run looks good again d10-15. GEFS look pretty good too. We better score in the next 2 weeks before the Cansips cancels winter. 

I don't think we should sleep on the 6th-7th.  Interesting look on the Euro with a low over ky and high pressure all over the ne.  Longshot, but its there.

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9 minutes ago, WinterWxLuvr said:

I don't think we should sleep on the 6th-7th.  Interesting look on the Euro with a low over ky and high pressure all over the ne.  Longshot, but its there.

If it starts to look interesting you know I'll say something. Good consensus for cold chasing precip frontal kind of deal. The gradient is at a bad angle for anything type of wave to run the gauntlet. At this point it doesn't look hopeful at all. 

One thing I'm looking forward to is the frontal passage. I'm sure there will be some strong winds and rapid temp drops. Should get us in the mood at least. 

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54 minutes ago, Bob Chill said:

Euro op spat out another decent look after the big front. Very different than the GFS quick ridge. My guess is the eps run looks good again d10-15. GEFS look pretty good too. We better score in the next 2 weeks before the Cansips cancels winter. 

Nice eps run.  Close to weenie territory like a couple days ago.

Sorry Cansips, winter cancel cancel.

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The thing about seasonals is they can easily miss atypical features that end up becoming dominant players for extended periods of time or features are in modestly different places than depicted. I didn't think the Dec cansips looks that bad to be honest. It was like +.5* for Dec with low heights in the 50/50 area and higher heights pressing into GL. Overall FAR from a disaster even as is. Not great but not something to worry over. 

The problem I see with it potentially busting is the aleutian ridge pushes into siberia instead of poleward and the trop pv is dead center over the pole. What if the persistence with the aleutian ridge is to press poleward? It's not "that" big of a difference for a hemispheric mean pattern but the implication in the US are pretty big. Poleward alueutian ridge = cold delivery into the conus more often than not. 

Here's a great example of what I'm talking about:

Cansips Dec h5:

cansipsdec.JPG

 

Very strong aleutian ridge obviously but a consolidated PV dead center. Not good overall but still workable. Cold source in western canada remains intact and no WAR so cutters aren't guaranteed. I haven't a clue if this is how things go down. Just talking about what the panel implies. 

 

Now look at the d10-15 mean with the 12z EPS:

epsd10-15.JPG

 

Aluetian ridge closes off over the arctic ocean/ESS. This helps push lower heights into the eastern Conus because the trop PV is displaced of the pole. Not a huge difference from the cansips as far as hemispheric patterns go but big difference in sensible wx in the US. 

The strat PV is still weak and taking some hits. Until that changes and the constantly advertised higher heights near the pole go away there is good reason to doubt the cansips.  

 

 

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5 minutes ago, C.A.P.E. said:

Nice eps run.  Close to weenie territory like a couple days ago.

Sorry Cansips, winter cancel cancel.

Looked great huh?! We've had quite a few good runs lately and the timetable isn't changing. I'm itching for the first real track. Probably won't be too long. It could come easy within the next 2 weeks...heh...lol...

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8 hours ago, Round Hill WX said:

Since we're talking about it....

Cansips DJF from 12/1/16

Cherry picking the last two months to validate a seasonal tool is nearly using anecdote to prove your point.  The actual data tells another story.  Verification scores for our area from their own interface for the last 12 months ending yesterday tells the actual story.  They are just a smidge to the right of climatology.  Like 0.1 standard deviations to the right:

CanSIPS.png

Merryfield, et. al., got funding and spent 6 years building that thing, it's been in PROD since 2012 and that's the result?  Yikes, especially since it was funded to solve poor long-lead forecasting issues in winter on the CA west coast and summer in eastern CA.

 

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Just now, Bob Chill said:

Looked great huh?! We've had quite a few good runs lately and the timetable isn't changing. I'm itching for the first real track. Probably won't be too long. It could come easy within the next 2 weeks...heh...lol...

Was just looking at the 2m temp anomalies on the mean. Other than a day or 2 near avg, days 8-15 are solidly below. Snow mean isn't bad either, generally 1-3" for areas east of the mountains. I am still thrilled to see whats being advertised isn't shifting, and confidence is building we wont see anything reminiscent of last December.

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6 minutes ago, Bob Chill said:

Winwxluvr broke the weeklies. Lol. Worst run in a couple weeks.

lol Cansips ftw?

Its not a great run, but could be far worse. Seems to be indicative of general uncertainty with the pattern going forward.  NA blocking seems to be there for the most part. I'll hang my hat on that. Meanwhile we better score something in the next 15 days ;) 

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1 hour ago, das said:

Cherry picking the last two months to validate a seasonal tool is nearly using anecdote to prove your point.  The actual data tells another story.  Verification scores for our area from their own interface for the last 12 months ending yesterday tells the actual story.  They are just a smidge to the right of climatology.  Like 0.1 standard deviations to the right:

CanSIPS.png

Merryfield, et. al., got funding and spent 6 years building that thing, it's been in PROD since 2012 and that's the result?  Yikes, especially since it was funded to solve poor long-lead forecasting issues in winter on the CA west coast and summer in eastern CA.

 

I agree with you. The two individual months were just to show 1 month lead times. The summer months were also pretty similiar. 

In your example you used 12 month verification. With any forecast, whether seasonal, monthly, etc., the objective is to predict anomalies, or departures from normal. 

Climate forecasts are inherently probalistic due to the butterfly effect, thus the need for ensemble predictions. 

So when measuring the skill or performance of the model, the anomaly correlation of predicted and observed anomalies in past forecasts will inherently be less accurate over time. 

The one month lead example I showed carries a more reasonable verification score.

 I know you know all this but I think that some totally dismiss the climate models(particularly 1-3 month leads) as a coin flip. It's just another tool to use and can be insightful if expectations are not biased.

 

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15 minutes ago, C.A.P.E. said:

lol Cansips ftw?

Its not a great run, but could be far worse. Seems to be indicative of general uncertainty with the pattern going forward.  NA blocking seems to be there for the most part. I'll hang my hat on that. Meanwhile we better score something in the next 15 days ;) 

Blocking

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13 hours ago, Bob Chill said:

Meanwhile, before the seasonal disaster plays out as depicted on the cfs/candsips...the 0z ens suite looked really good. Odds improving for scoring something before fireballs rain from the sky leaving behind scorched earth and ashes. 

 

10 hours ago, Bob Chill said:

Yea, I'm a bit shook up with the cansips. Cancelling winter on Dec 1st is tradition that should never be discounted. 

We'll probably go through the typical "carving" of the trough/baroclinic zone and get things just right after a couple fronts and watch our first nice setup go to complete waste. Then rinse repeat until 60* on Xmans. 

 

Heh!!  If I didn't know any better, I'd be tempted to say that Bob is doing some serious trolling of the CANSIPS!! :lol:

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