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March 13 - 15 Major Winter Storm Potential


NEG NAO

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1 minute ago, NortheastPAWx said:

What's the lead time for blizzard warnings? Assuming no dramatic last-second shift...

Blizzard Warning

A Blizzard Warning means that the following conditions are occurring or expected within the next 12 to 18 hours.


1) Snow and/or blowing snow reducing visibility to 1/4 mile or less for 3 hours or longer
AND
2)  Sustained winds of 35 mph or greater or frequent gusts to 35 mph or greater.
There is no temperature requirement that must be met to achieve blizzard conditions.

 

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10 minutes ago, bluewave said:

The really detailed Euro products will be out soon so we can see if it comes in a little closer with stronger impacts like the UKIE did.

 

What you do not want is 70mph gusts and a heavy wet snow. That's a recipe for major power outages. Based on the wind direction with even the tucked in track I doubt we see more then moderate flooding. Something on par with what we saw in January.

major coastal flooding and heavy snow ala 93 and 78 is pretty incredible stuff as I have talked about in the past. Ice bergs that flash freeze into impenetrable ice after the water recedes 

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MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
100 PM EDT SUN MAR 12 2017

VALID MAR 12/1200 UTC THRU MAR 16/0000 UTC

...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...

12Z MODEL EVALUATION...INCLUDING THE NAM AND GFS

...AMPLIFYING SHORTWAVE DIGGING TOWARD THE MID MS/LOWER OH/TN
VALLEYS THROUGH MON...
...TROUGH GOING NEGATIVE TILT ACROSS THE MID-ATLANTIC/NEW ENGLAND
THROUGH TUES...
...PARENT SURFACE LOW CROSSING THE MID MS/OH VALLEYS THROUGH MON...
...INTENSE SECONDARY CYCLOGENESIS ALONG THE EAST COAST MON
NIGHT/TUES...
...DEEP UPPER LOW EVOLVING OVER THE GREAT
LAKES/MID-ATLANTIC/NORTHEAST TUES/WED...
 
PREFERENCE: BLEND OF THE 12Z GFS/00Z ECMWF...THROUGH 48 HOURS
            BLEND OF THE 00Z UKMET/00Z ECENS MEAN...AFTER 48 HOURS
CONFIDENCE: AVERAGE....BECOMING BELOW AVERAGE
 
A STRONG SHORTWAVE TROUGH CURRENTLY EXITING THE NORTHERN ROCKIES
WILL DIG DOWN THE EAST SIDE OF THE STRENGTHENING WEST COAST RIDGE
AXIS AND AMPLIFY ACROSS THE MID MS/LOWER OH AND TN VALLEYS TONIGHT
THROUGH MON. THIS WILL DRIVE A WELL-DEFINED AREA OF LOW PRESSURE
INITIALLY OVER EASTERN WY EAST-SOUTHEAST ACROSS THE MID MS VALLEY
EARLY MON AND INTO THE OH VALLEY BY LATE MON. THE AMPLIFYING
NORTHERN STREAM SHORTWAVE WILL BEGIN TO BACK THE MID LEVEL FLOW
ALONG THE EAST COAST...AND WILL INITIATE A SECONDARY CYCLOGENESIS
OFF THE SOUTHEAST COAST EARLY TO MIDDAY ON MON IN VICINITY OF A
STRENGTHENING BAROCLINIC ZONE JUST OFF THE MID-ATLANTIC AND
SOUTHEAST COAST. THE UPSTREAM SHORTWAVE IS THEN EXPECTED TO GO
NEGATIVE TILT AS IT CROSSES THE CENTRAL APPALACHIANS MON NIGHT AND
THE MID-ATLANTIC AND NEW ENGLAND ON TUES. THIS WILL RESULT IN
RAPIDLY DEEPENING LOW PRESSURE THAT WILL LIFT NORTHEAST UP OFF THE
MID-ATLANTIC AND NEW ENGLAND COASTS MON NIGHT AND TUES.

REGARDING THE AMPLIFYING SHORTWAVE REACHING THE OH/TN
VALLEYS...THERE IS RATHER GOOD AGREEMENT WITH TIMING AND DEPTH OF
THE ENERGY UNTIL MON EVENING WHEN THE 12Z NAM AND 00Z ECMWF BEGIN
TO LAG THE MODEL CONSENSUS A LITTLE AND ALSO TEND TO BE PERHAPS A
TAD DEEPER. AS THE ENERGY GOES NEGATIVE TILT ACROSS THE
MID-ATLANTIC AND NORTHEAST MON NIGHT/TUES...THE 00Z UKMET AND 00Z
CMC BECOME THE STRONGEST SOLUTIONS WITH THE REMAINING MODELS
CLUSTERED A LITTLE WEAKER.

AT THE SURFACE...THE 12Z GFS HAS TRENDED A BIT SLOWER AND A TAD
FARTHER SOUTHWEST WITH ITS CYCLOGENESIS OFF THE SOUTHEAST COAST
SOUTH OF WILMINGTON NC BY MON EVENING...AND OVERALL HAS TRENDED
CLOSER TO THE 00Z ECMWF AND 00Z UKMET CLUSTER. AT 48 HOURS/12Z
TUES...THE 12Z GFS REFLECTS A ECMWF/UKMET COMPROMISE WITH GOOD
CLUSTERING. THEREAFTER...THE 12Z GFS BEGINS TO SHIFT ITS TRACK
AGAIN A BIT EAST OF THE MODEL CONSENSUS AND ALSO A BIT FASTER. THE
00Z UKMET/00Z CMC AND 00Z ECMWF ALL TUCK LOW PRESSURE IN CLOSER TO
SOUTHERN NEW ENGLAND...AND THIS IS SUPPORTED BY THE 12Z NAM AS
WELL. AS THE LOW PRESSURE LIFTS OFFSHORE SOUTHERN NEW
ENGLAND...THE 00Z ECMWF GRADUALLY BECOMES THE SLOWEST
SOLUTION...AND THE 00Z UKMET BECOMES THE DEEPEST OWING TO ITS
STRONGER SUPPORT ALOFT. THE ECMWF/CMC-BASED ENSEMBLE MEMBERS FAVOR
THE MORE WESTWARD LEANING DETERMINISTIC GUIDANCE AWAY FROM THE
GFS...ALTHOUGH THE GFS-BASED MEMBERS COLLECTIVELY STILL FAVOR A
TRACK FARTHER EAST. AT THIS TIME...WILL RECOMMEND A BLEND OF THE
GFS AND ECMWF THROUGH 48 HOURS GIVEN ITS BETTER MODEL
CLUSTERING...BUT THEN WILL FAVOR A BLEND OF THE WELL-CLUSTERED
UKMET/ECENS MEAN THEREAFTER TO APPROXIMATE THE MODEL
CONSENSUS...AS THE DETERMINISTIC ECMWF APPEARS TO BE A BIT TOO
SLOW. CONFIDENCE AFTER 48 HOURS WILL BECOME BELOW AVERAGE GIVEN
THE LEVEL OF MODEL SPREAD.

BY LATER TUES AND WED...THE MODELS SHOW A STRONG UPPER TROUGH AND
ASSOCIATED CLOSED LOW DROPPING DOWN OVER THE GREAT LAKES WHICH
THEN EVOLVES OVER THE NORTHEAST U.S. THROUGH WED. A GENERAL MODEL
COMPROMISE WILL BE FAVORED WITH THIS LARGE SYNOPTIC SYSTEM AT THIS
POINT.


...AMPLIFYING TROUGH/DEEPENING SURFACE LOW OFF THE PACIFIC
NORTHWEST ON TUES/WED...

PREFERENCE: BLEND OF THE 12Z GFS AND 00Z ECMWF
CONFIDENCE: BELOW AVERAGE

MOST OF THE MODELS SHOW A LONGWAVE TROUGH AMPLIFYING OFFSHORE THE
PACIFIC NORTHWEST BY TUES ALONG WITH A POSSIBLE AREA OF LOW
PRESSURE DEEPENING AS IT LIFT NORTHEAST TOWARD BRITISH COLUMBIA
COAST BY TUES NIGHT AND WED. THERE IS CONSIDERABLE DISAGREEMENT
WITH THE DETAILS OF THE SURFACE LOW DEVELOPMENT...AS THE 00Z CMC
IS MORE PROGRESSIVE WITH THE HEIGHT FALLS AND LOW CENTER...WITH
THE 00Z UKMET SLOWER. THE 00Z ECMWF ALONG WITH THE 12Z NAM AND 12Z
GFS ACTUALLY SHOW A MUCH MORE ILL-DEFINED WAVE TRAVERSING AN
APPROACHING COLD FRONT. THE 06Z GEFS MEAN AND 00Z ECENS MEAN BOTH
FAVOR A WEAKER/FLATTER WAVE BUT ALL AGREE ON AN APPROACHING COLD
FRONT IN THE PACIFIC NORTHWEST BY WED. THE 12Z NAM MAY BE A BIT
TOO PROGRESSIVE...SO FOR NOW WILL LEAN TOWARD A GFS/ECMWF BLEND
WITH LIMITED CONFIDENCE GIVEN CONCERNS OVER THE LOW DEVELOPMENT.


...SOUTHERN STREAM UPPER TROUGH NEAR SOUTHERN CA/BAJA PENINSULA BY
WED...

PREFERENCE: GENERAL MODEL COMPROMISE
CONFIDENCE: ABOVE AVERAGE

THE MODELS SUGGEST A WEAK SOUTHERN STREAM UPPER TROUGH WILL BE
APPROACHING SOUTHERN CA AND THE BAJA PENINSULA BY WED. MODEL
SPREAD OVERALL IS RELATIVELY MINOR AT THIS POINT...SO A GENERAL
MODEL COMPROMISE WILL BE PREFERRED.


www.wpc.ncep.noaa.gov/html/model2.shtml...

www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml...

ORRISON

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3 minutes ago, LongBeachSurfFreak said:

What you do not want is 70mph gusts and a heavy wet snow. That's a recipe for major power outages. Based on the wind direction with even the tucked in track I doubt we see more then moderate flooding. Something on par with what we saw in January.

major coastal flooding and heavy snow ala 93 and 78 is pretty incredible stuff as I have talked about in the past. Ice bergs that flash freeze into impenetrable ice after the water recedes 

The full moon will also make the floods worse, and the storm will be close during Tues AM's high tide. I'm rooting for a more offshore track for that reason too. A hugger track piles much more water in. 

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1 minute ago, Juliancolton said:

They do... at least out to 72 hours, not sure about after that. http://meteocentre.com/numerical-weather-prediction/map-explorer.php?mod=ukmet

Thanks!  Someone was posting UK panels last night and it was only one frame per 24 hrs :( maybe because it was beyond 72 hours (they posted a 72 hr frame and a 96 hr frame, but there was nothing in between.)

 

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2 minutes ago, UlsterCountySnowZ said:

Wod this translate to us too? Isn't it a 72hr correlation plot for NH?

I don't think anybody would weigh model solutions based solely on upper air verification scores, but it's just a good way of illustrating that it has a good grasp on large-scale patterns. I couldn't really get into the nuances of how this information might be used... perhaps a red tagger could chime in and shed some light

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6 minutes ago, UlsterCountySnowZ said:

Wod this translate to us too? Isn't it a 72hr correlation plot for NH?

Excellent graphic post- I remember awhile back someone posted a graphic of the verification scores of the various GFS runs and the 6z and 18z runs scored the lowest.

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1 minute ago, Stormlover74 said:

No it went from 1245 to 145 so coming out now. I know, it gets confusing

Oh wait that's right.  I was thinking 2 PM but then added an extra hour by mistake haha.

I would do away with the :45 because these things take awhile to load it and just say it's 2 PM for the OP and 3:30 for the EPS.  Better to round it off to the nearest 30 min :P

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1 hour ago, UlsterCountySnowZ said:

Widespread 18-24 on ggem lol

I think the CMC is close to a best case scenario for the urban corridor and NW suburbs.  Widespread 2"+ LE with a climatologically cold airmass.  Ratios could exceed 10:1 and the model probably doesn't fully take into account banding.  I think you'd see a lot of 20-30" totals if that synoptic evolution actually occurred.  It's a really beautiful run.  Very high intensity precipitation for a medium length duration.

But I would definitely hedge at least halfway towards the GFS solution at this point.  The big coastals tend to take an offshore track, close to the 12z GFS track, especially in recent years.  

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1 minute ago, eduggs said:

I think the CMC is close to a best case scenario for the urban corridor and NW suburbs.  Widespread 2"+ LE with a climatologically cold airmass.  Ratios could exceed 10:1 and the model probably doesn't fully take into account banding.  I think you'd see a lot of 20-30" totals if that synoptic evolution actually occurred.  It's a really beautiful run.  Very high intensity precipitation for a medium length duration.

But I would definitely hedge at least halfway towards the GFS solution at this point.  The big coastals tend to take an offshore track, close to the 12z GFS track, especially in recent years.  

Hopefully the trend towards more digging stops at this point, that would amplify the trough and force a track very close to the shore. GGEM was great this run but another tick west and the low's over NJ and there would be a good amount of taint into NYC even. 

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1 minute ago, Paragon said:

Wait the EPS is now going to be 4:30, not 3:30? Oh man, I thought the EPS came out about an hour and a half after the Euro, not two and a half hours later.....

EPS Panels starred at 230pm before we changed the clocks so now it's 330pm

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