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Winter Storm 1/6 - 1/8, 2017


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2 minutes ago, SnowGoose69 said:

FWIW since the Euro upgrade was released last winter I've found its tended to have significant suppression issues on storm systems in the 48-96 hour range at times.  The January blizzard was one where it performed badly until inside 48 hours, although it was not yet officially operational until 2/15 or so.

Yeah, we've really come a long way on our forecast technology if we have to wait for "long range" models to get inside of 48hrs for decent predictability on storm track

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Just now, packbacker said:

That was from yesterday...today's is a euro solution but more progression and brings SLP inland...way inland.

 

 

Whoops! Didn't notice the date, figured WxBell would be current. Thanks!

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5 minutes ago, SnowGoose69 said:

FWIW since the Euro upgrade was released last winter I've found its tended to have significant suppression issues on storm systems in the 48-96 hour range at times.  The January blizzard was one where it performed badly until inside 48 hours, although it was not yet officially operational until 2/15 or so.

Sir...you mentioned in a previous thread the pattern doesn't fit suppression but a more northerly solution.  Yet the Euro and other models save the GFS want to suppress the shortwave even at this time.  Why is that?

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Just now, CAD_Wedge_NC said:

Yes but did he take out all the low outliers as well? You can't just discount some members of an ensemble because you think it will not occur. That's the purpose of averaging everything together.

Isn't that what the eM panel is?

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Just now, BristowWx said:

Sir...you mentioned in a previous thread the pattern doesn't fit suppression but a more northerly solution.  Yet the Euro and other models save the GFS want to suppress the shortwave even at this time.  Why is that?

Its completely a perfect thread the needle timing issue IMO.  The shortwave ejects out in the flow at the optimal time for the system to be staying more south.  A slight change in that time it begins ejecting out of the NW US and major changes may happen

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C1MAWDtVQAIbFwU.jpg:large

 

5 minutes ago, CAD_Wedge_NC said:

Yes but did he take out all the low outliers as well? You can't just discount some members of an ensemble because you think it will not occur. That's the purpose of averaging everything together.

 

There were literally only three ensemble members (out of like 20) with less than 2 inches for RDU, according to the graph. He's just stirring the pot, as usual. See for yourself.

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5 minutes ago, chapelhillwx said:

C1MAWDtVQAIbFwU.jpg:large

 

 

There were literally only three ensemble members (out of like 20) with less than 2 inches for RDU, according to the graph. He's just stirring the pot, as usual. See for yourself.

If I'm reading that correctly, the mean is a little less than 4, correct?

 

Take out those astronomically high outliers at the top and the mean goes down to around 2 inches.

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5 minutes ago, SnowGoose69 said:

Its completely a perfect thread the needle timing issue IMO.  The shortwave ejects out in the flow at the optimal time for the system to be staying more south.  A slight change in that time it begins ejecting out of the NW US and major changes may happen

Thank you.  I guess we know what the task at hand is...watch 500mb and see what happens as it ejects the shortwave.  If things are going to trend in a direction on the GFS it should start fairly soon I would think.  If not 18z then 0z perhaps.  

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3 minutes ago, PackGrad05 said:

If I'm reading that correctly, the mean is a little less than 4, correct?

 

Take out those astronomically high outliers at the top and the mean goes down to around 2 inches.

You don't get to just change the mean around to fit your narrative like that. You could just as easily say anything below 2 inches is a low outlier and take those out instead.

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3 minutes ago, PackGrad05 said:

If I'm reading that correctly, the mean is a little less than 4, correct?

 

Take out those astronomically high outliers at the top and the mean goes down to around 2 inches.

Left out the bottom 4 and left out the top 4 that are over 14", added up the others and averages it out, and the mean was 4.5"... not bad 

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1 minute ago, chapelhillwx said:

You don't get to just change the mean around to fit your narrative like that. You could just as easily say anything below 2 inches is a low outlier and take those out instead.

But when most of the members are clumped that closely together at the bottom, are any of those statistically considered outliers?

 

The ones at the top are many standard deviations higher than the rest, which is why I threw them out.  I understand what you're saying, I just interpret the statistics different.  

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1 minute ago, CaryWx said:

Euro has highest verification scores at 5 days right?  Was the 12z euro wheelhouse for Sat at noon (gmt)

Euro is #1, UKMET #2.  .927 and .915 I believe respectively.  GFS is .903 or so.  The Euro is prone to error though til about 72 hours.  Inside 72 its rarely making major shifts at that point.

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EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1100 AM EST MON JAN 02 2017

VALID 12Z THU JAN 05 2017 - 12Z MON JAN 09 2017

PATTERN OVERVIEW...

THE LARGE-SCALE PATTERN IS MOSTLY INFLUENCED BY A RETROGRADING
UPPER RIDGE OR HIGH OVER ALASKA WHICH THEN MAKES WAY FOR AN
AMPLIFYING UPPER TROUGH OR UPPER LOW OVER EASTERN CANADA BY NEXT
WEEKEND...ALONG WITH A SLOWLY EVOLVING UPPER TROUGH OVER
ONTARIO/QUEBEC...WITH THESE FEATURES SUPPORTING A POSSIBLE
HIGH-END PRECIPITATION EVENT FOR CALIFORNIA NEXT SATURDAY THROUGH
MONDAY...A TRANSIENT PATTERN FROM THE ROCKIES EASTWARD...AND
CYCLOGENESIS SOMEWHERE OVER THE WESTERN ATLANTIC FRIDAY THROUGH
SUNDAY.

MODEL CHOICES AND CONFIDENCE...

TWO CAMPS OF SOLUTIONS EMERGE AT THE START OF DAY 3/THU...WITH THE
00Z GFS MORE PROGRESSIVE WITH SHORTWAVE TROUGHS CROSSING CENTRAL
CANADA...THUS PRODUCING MORE SEPARATION WITH THE RESIDUAL TROUGH
ACROSS THE NORTHWEST...AND THEREFORE ALLOWING THE NORTHWEST TO
REMAIN UNDER THE INFLUENCE OF THE TROUGH LONGER. THE OTHER CAMP OF
SOLUTIONS IS REPRESENTED BY THE 00Z ECMWF WHICH IS SLOWER WITH THE
CENTRAL CANADA TROUGH...THUS ALLOWING IT TO SLIGHTLY PHASE WITH
THE RESIDUAL TROUGH OVER THE NORTHWEST...WHICH THEN ALLOWS THE
TROUGH TO EXIT THE NORTHWEST MORE QUICKLY. WHILE THE ENSEMBLE
MEMBER SPREAD IS HIGH...THEREFORE INDICATING LOW
CONFIDENCE...RUN-TO-RUN CONTINUITY HAS BEEN HIGHER WITH THE
ECMWF-SCENARIO...WITH THE 06Z GFS AND 00Z PARALLEL GFS LEANING
STRONGLY IN THE ECMWF DIRECTION. COMBINE THE 00Z CANADIAN...AND
ITS LOOKING MORE AND MORE LIKE THE 00Z GFS IS THE ODD MODEL OUT.
THUS...THE PREFERENCE IS ABOUT 70 PERCENT IN THE ECMWF DIRECTION
FOR ALL 7 DAYS...WITH MORE DETERMINISTIC SOLUTIONS BLENDED EARLY
FOR DETAIL AND AMPLITUDE...AND MORE ENSEMBLES USED LATE DUE TO
HIGHER UNCERTAINTY. THESE CHOICES HOLD AS WELL FOR THE EAST
COAST...WHICH IF THE 00Z GFS WERE TO BE CORRECT...WOULD SUPPORT A
WINTER STORM FOR PARTS OF THE EAST COAST NEXT SUNDAY.
HOWEVER...FOR REASONS LISTED ABOVE...ITS SOLUTION IS NEAR THE
WESTERN AND DEEP EDGES OF THE GUIDANCE...WITH ONLY ABOUT 4 OUT OF
100 ENSEMBLE MEMBERS SUPPORTING IT AT THIS TIME. INSTEAD...PREFER
A SOLUTION MORE OFFSHORE AND PROGRESSIVE.

SENSIBLE WEATHER IMPACTS...

BELOW NORMAL TEMPERATURES CAN BE EXPECTED FOR MUCH OF THE U.S
EXCEPT THE SOUTHWEST FOR THURSDAY TROUGH SATURDAY BEFORE SOME
MODERATION DEVELOPS FOR THE INTERMOUNTAIN WEST/ROCKIES/PLAINS AS
THE UPPER TROUGH FORMS NEAR BRITISH COLUMBIA. OTHERWISE...A
POTENTIALLY HIGH-END ATMOSPHERIC RIVER EVENT IS POSSIBLE FOR
CALIFORNIA NEXT SATURDAY THROUGH MONDAY...WITH 48-HR LIQUID
EQUIVALENT AMOUNTS OF 2 TO 5 INCHES FOR THE COASTAL RANGES...AND
PERHAPS 5 TO 10 OR 12 INCHES FOR THE SIERRAS. THE EXTREME AMOUNTS
ARE WELL SUPPORTED BY THE ALL OF THE ENSEMBLES SUITES...INCLUDING
GEFS/ECMWF/CANADIAN...AS THE RESIDUAL MOISTURE PLUME CURRENTLY
EAST OF HAWAII LIFTS NORTHWARD AND IS PULLED ACROSS CALIFORNIA
WITH PW ANOMALIES NEARING 4 STANDARD DEVIATIONS ABOVE NORMAL AND
PW RETURN INTERVALS NEARING 30 YEARS. 

JAMES

 

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Updated wpc model preference with 12z runs. They like the 12z uk..which seems like a good compromise 


UPPER LOW IN THE VICINITY OF THE PACIFIC NORTHWEST THROUGH MID-WEEK
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z UKMET/00Z ECMWF MEAN BLEND
CONFIDENCE: SLIGHTLY BELOW AVERAGE

THE 00Z ECMWF APPEARS TOO FAST TO DROP THE CLOSED LOW SEWD INTO
THE WRN U.S. ON WED/WED NIGHT WITH ITS OWN ENSEMBLE MEAN HELD BACK
SOME. THE 12Z ECMWF ADJUSTED A BIT SLOWER WHICH SEEMS LIKE A STEP
IN THE RIGHT DIRECTION BUT THE 12Z ECMWF STILL APPEARS FASTER. ON
THE FLIP SIDE...THE 12Z NAM/GFS INSIST ON HOLDING ONTO THE CLOSED
LOW ALONG THE PACIFIC NORTHWEST COAST LONGER THAN THE REMAINING
DETERMINISTIC GUIDANCE. ENSEMBLE SPREAD IS RATHER LARGE...BUT
STAYING AWAY FROM THE EDGES OF THE ENSEMBLE SPREAD SUPPORTS A
POSITION NEARER TO THE MIDDLE...BEST SUPPORTED BY THE 12Z UKMET.


POSITIVELY-TILTED MID-LEVEL TROUGH SINKING THROUGH THE NORTHERN
  PLAINS WED NIGHT
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z UKMET/00Z ECMWF MEAN BLEND
CONFIDENCE: BELOW AVERAGE

THIS SYSTEM TIES INTO THE SYSTEM REFERENCED ABOVE. THE LATEST
DETERMINISTIC AND ENSEMBLE GUIDANCE SHOWS THE 00Z UKMET AND
GEFS/GFS QUICKER AND DEEPER BUT THESE MODELS HAVE BEEN TRENDING
LESS AMPLIFIED OVER THE PAST 4 CYCLES. A TIMING TOWARD THE MIDDLE
OF THE NON GEFS BASED ENSEMBLES
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3 minutes ago, SnowGoose69 said:

Euro is #1, UKMET #2.  .927 and .915 I believe respectively.  GFS is .903 or so.  The Euro is prone to error though til about 72 hours.  Inside 72 its rarely making major shifts at that point.

Thanks Goose

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2 minutes ago, PackGrad05 said:

But when most of the members are clumped that closely together at the bottom, are any of those statistically considered outliers?

 

The ones at the top are many standard deviations higher than the rest, which is why I threw them out.  I understand what you're saying, I just interpret the statistics different.  

Yeah, I understand what you mean too. It just seems like when there are a few members with a certain solution, it's worth including in the mean despite them being extreme. Then again, we all get screwed by the SREFS lol.

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