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November 2013 Observations & Discussions


Rtd208

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The CFS monthly from the last few days of the previous have been a useful tool for monthly forecasts. 

But it has its good and bad months like every other forecast beyond the 6-10 day range. 6-10 day

temperature forecasts using the Euro ensemble mean is an achievement that was not possible

before the arrival of ensemble forecasting. I grew up during an era when 24 hr forecasts were 

often a big surprise. So modeling has come a long way. But I think that some people expect too

much and get disappointed when a particular operation run past 120 hrs doesn't work out.

That's getting into the range when you should be relying on the ensembles anyway.

 

http://www.cpc.ncep.noaa.gov/products/people/mchen/CFSv2FCST/monthly/

I love ensemble modeling.  I think it's really useful in the 6-10 day range.  But even in this range I think our current state of ensemble modeling fails to reflect the true scope of possible variability.  Ensembles usually cluster too close to the parent model and there is just too much variability to get more than a general picture.

 

Beyond about 14 days, ensemble modeling seems a lot less useful to me.  At this time range, the ensemble mean will not likely reflect anything close to the final solution.  The range and mean do suggest something about the likelihoods of overall weather patterns, but with only limited skill.  This is evidence by poor run to run consistency and low verification scores.

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The analogs for December are hinting that we will break the warm streak that we saw in

2011 and 2012. The last two Decembers were the 6th time since 1950 that NYC saw 

two 39.0 or higher Decembers in a row. Since many of these analogs were from a 

colder era, the down signal from last year may only result in closer to normal 

rather than a below normal December. So I don't think that we are going to see 

another 40 degree or warmer  December this year.

 

December 11-12

 

 

Similar two year composite

 

 

Third December composite

 

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The pattern still looks progressive. I wouldn't count on any major winter storms, next few weeks.

 

Meanwhile, we are in 5% percent t on Day 2 and 3 outlooks, we still have to watch for low-topped squall line to make it here, from the Ohio Valley.

 

day2probotlk_0700_any.gif

...NERN U.S....
   STORMS WILL EVENTUALLY OUTPACE THE AXIS OF RICHER LOW LEVEL MOISTURE   LATER SUNDAY NIGHT AND ENCOUNTER MUCH WEAKER INSTABILITY AS THEY   APPROACH THE NERN STATES. HOWEVER...SOME THREAT FOR DAMAGING WIND   MAY PERSIST WITH REMAINING LOW TOPPED CONVECTION LATE THIS PERIOD.

day3prob_0830.gif

..SRN NEW ENGLAND...   A FORCED LOW TOPPED LINE OF CONVECTION WITH LITTLE TO NO LIGHTNING   WILL LIKELY BE IN PROGRESS ALONG THE COLD FRONT ACROSS NEW ENGLAND.   THIS CONVECTION WILL BE EMBEDDED WITHIN MEAGER CAPE BUT A VERY   STRONG KINEMATIC ENVIRONMENT ALONG A 60+ KT LLJ. AT LEAST A LOW END   THREAT FOR DAMAGING WIND WILL PERSIST WITH THIS ACTIVITY AS IT   CONTINUES EWD AND OFFSHORE...ESPECIALLY OVER SRN NEW ENGLAND WHERE   INSTABILITY WILL BE SLIGHTLY GREATER.
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I believe that NYC north will have a snowy period during the holidays

I agree 100% with this statement since all the major indicies are pointing towards a pattern change as we approach Thanksgiving and the 6Z GFS shows in the later images as you scroll through this that the arctic air is not so quick to leave as a negative NAO and AO is developing

 

http://www.met.sjsu.edu/weather/models/gfsone-12/ex_all850tmpc.html

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I agree 100% with this statement since all the major indicies are pointing towards a pattern change as we approach Thanksgiving and the 6Z GFS shows in the later images as you scroll through this that the arctic air is not so quick to leave as a negative NAO and AO is developing

 

http://www.met.sjsu.edu/weather/models/gfsone-12/ex_all850tmpc.html

We have to watch for a storm during this timeframe. Good chance of it happening with the indicies like that.

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It going to be tough to break the dry pattern in here with the models reloading the -EPO

ridge in the long range. NYC hasn't seen a heavy rain since 9-22. The massive blocking pattern

over the Pacific has weakened  the Pacific Jet and you can see the dry conditions across the U.S.

and especially the East

 

 

 

.

 

 

 

 

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It going to be tough to break the dry pattern in here with the models reloading the -EPO

ridge in the long range. NYC hasn't seen a heavy rain since 9-22. The massive blocking pattern

over the Pacific has weakened  the Pacific Jet and you can see the dry conditions across the U.S.

and especially the East

 

attachicon.gif500.gif

 

attachicon.gif300.gif

 

attachicon.gif60dPDeptUS.png.

When do you think this dry pattern will break?  Personally, I am worried that drier than normal is the new normal.

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The 12z GFS was very impressive for rainfall next weekend. It has a wash out for most of Saturday and all of Sunday. The 12z Euro is also 1"+ however its bias of holding too much energy back in the southwest made an overall impact. Either way next weekend looks wet. The GFS also has good model support from the GEFS. The GGEM which has been much more progressive lately blows everything up off the coast which is odd since it usually over amplifies systems in the long range.

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The 12z GFS was very impressive for rainfall next weekend. It has a wash out for most of Saturday and all of Sunday. The 12z Euro is also 1"+ however its bias of holding too much energy back in the southwest made an overall impact. Either

way next weekend looks wet. The GFS also has good model support from the GEFS. The GGEM which has been much more progressive lately blows everything up off the coast which is odd since it usually over amplifies systems in the lo

ng range.

Euro's snowmap shows a couple of inches to the north of the area with the day 6-7 event.

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When do you think this dry pattern will break?  Personally, I am worried that drier than normal is the new normal.

 

It's hard to say since we have been in a dry pattern for almost two years now. But the extreme dry pattern since mid-September

really stands out.

 

 

 

 

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Euro unleashes the Arctic hounds tday week. 3rd run in a row

 

That Arctic high entering Montana in  a week then moving East has good ensemble support. That's

what JB would call the emperor of the north. I would guess near or record lows over the Rockies

and Plains filtering east.

 

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