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December 9th 2017 Crusha or brusha?

WeatherFeen2000

By WeatherFeen2000,
in New York City Metro

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Rjay

Rjay

Posted
Posted

PREFERENCE: BLEND OF 12Z ECMWF / 12Z NAM / 12Z UKMET CONFIDENCE: SLIGHTLY ABOVE AVERAGE THE AFOREMENTIONED SYSTEM ALONG THE GULF COAST WILL PLAY A ROLE UP THE EAST COAST AS THE ASSOCIATED EJECTING WAVE TRANSLATES NORTHEAST AND BEGINS TO PHASE WITH A DIGGING SHORTWAVE THROUGH THE GREAT LAKES REGION. THE RESULT SHOULD BE SURFACE CYCLOGENESIS ABOUT 250-300KM OFF THE EAST COAST. THE OVERALL TREND WITH THIS LOW OVER THE PAST SEVERAL MODEL CYCLES HAS BEEN TO NUDGE THE LOW TRACK CLOSER TO THE COAST. THIS IS EVIDENT IN THE GEFS AND ECMWF ENSEMBLE MEANS...AS WELL AS THE OPERATIONAL MODELS. ALL OF THE 12Z OPERATIONAL RUNS THAT ARE AVAILABLE SO FAR (NAM, GFS, UKMET) LOOK VERY SIMILAR IN TERMS OF LOW TRACK...BUT THE GFS IS STILL FASTER WITH TIMING BY APPROXIMATELY 6 HOURS. THE 00Z CMC AND 00Z ECMWF ARE STILL ABOUT A DEGREE OR TWO OF LONGITUDE EAST...BUT GIVEN THE OVERALL TRENDS...THEY MAY SHOW MORE SIMILARITY ON THE 12Z RUNS WHEN THEY ARRIVE. THE PREFERENCE WILL BE FOR A BLEND OF THE NAM...UKMET...AND ECMWF...WITH A SLIGHTLY HIGHER WEIGHT GIVEN TO THE NAM/UKMET SOLUTION OVERALL AS THE TREND IS IN THAT DIRECTION. 18Z UPDATE: NO CHANGE TO THE PRELIMINARY PREFERENCE. MODEL SPREAD ALSO CONTINUES TO NARROW WITH THE SYSTEM AS IT MOVES UP THE EAST COAST...AS WELL AS WITH THE DIGGING SHORTWAVE THROUGH THE GREAT LAKES. THE WESTWARD TREND OF THE SURFACE LOW TRACK HAS CONTINUED ON ALL THE MODELS...INCLUDING THE NEW 12Z ECMWF AND 12Z CMC. THE GFS CONTINUES TO LOOK LIKE A SLIGHTLY FASTER SOLUTION...DESPITE THE ECMWF TRENDING A LITTLE FASTER. A BLEND OF THE ECMWF/UKMET/NAM SHOULD YIELD A REASONABLE CONSENSUS SOLUTION AT THIS TIME...AS STATED WITH THE AFOREMENTIONED SYSTEM...WITH THE NEW ECMWF CAPTURING A SLIGHTLY FASTER POSSIBILITY ADVERTISED BY THE GFS/GEFS...AND THE CMC STILL SITTING ON THE EASTERN END OF MODELS WITH SURFACE LOW POSITION (AGAINST THE OVERALL TREND).

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Stormlover74

Stormlover74

Posted
Posted

Upton 

.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY NIGHT/...
Focus this time frame is the potential impacts of a coastal low (or
series of lows) that track to the south/southeast/then east of Long
Island Saturday-Saturday night.

The GFS remains a fast outlier, so has been discarded. The CMC
keeps vacillating from a track well out to sea, to a storm with
significant impacts on the area, the run to run inconsistencies, and
that it currently is bucking model trends of a solution closer to
the coast, has this model also being discarded. The SREF does not
cool the low levels to saturation, so its thermal profiles in the
low levels are too warm, it has been discarded for determining
rain/snow lines. The forecast Friday night-Sunday is thus based
primarily on a blend of the ECMWF/NAM/UKMET.

A northern stream kicker diving into the southern stream portion of
the deep layered trough Friday night will help to consolidate a broad
area of low pressure along the southeastern coast, into a less broad
and deeper area of low pressure off the Carolina coast by Saturday
morning. There still remains some difference in timing of onset of
sufficient isentropic lift to cause precipitation Friday night, for
now have limited pops to chance over mainly SE Suffolk County.

This shortwave then pushes up the Mid-Atlantic coast on Saturday,
helping to further consolidate and strengthen the surface low SE of
Long Island - most likely just to the SE of the 40N/70W benchmark.
As a result, the best chance of precipitation will be mainly from
NYC metro/SW CT on east - so have likely to categorical pops here.
This low then tracks to the NE Saturday night with he supporting
shortwave and a northern stream shortwave trough building into the
area. This trough then lifts to the NE on Sunday. As a result
gradually tapper off pops from W to E Saturday night and Sunday
morning.

In terms of sensible weather, expect any precipitation that falls
Friday night to be 1) mainly, if not entirely after midnight 2)
light 3) mainly as snow - with little if any accumulation. With
increasing isentropic lift on Saturday expect coverage and intensity
to increase. Wetbulb effect will bring temperatures down into the
lower-mid 30s across most of the region as this happens. As a result
expect a wet snow, with snow-liquid ratios around 7:1. This cooling
also will change any rain/rain-snow mix over coastal areas/NYC to
all snow.

For now looking at accumulations of generally 1-3 inches across the
Lower Hudson Valley/NE NJ/NYC (with less than an inch possible over
western Orange County, and 3-6 inches over S CT/Long Island, with
highest amounts over SE CT and parts of eastern Long Island.

There still remains though some uncertainty in terms of the
track/strength/timing of the low. If the westward trend with the
system continues, there will be the potential for more mixing near
the coast, limiting amounts over SE areas, and also increasing
snowfall amounts farther to the west. A track farther offshore, will
increase likelihood of mainly snow, but decrease amounts. For now,
will highlight the threat for the possibility of reaching winter
storm warning accumulations (6" or more) over S CT/Long Island.
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swamplover56

swamplover56

Posted
Posted

Goofus has initialized let's see if it goes more towards the euro, ukie, and nam. On a side note the ukie is def a underutilized model seems like a lot of these storms through the years when the ukie has been a outlier and remained consistent run to run the other models tend to trend in that direction

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WeatherFeen2000

WeatherFeen2000

Posted
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Posted
17 minutes ago, SnoSki14 said:

Models still trending west as we get closer, normally a good sign this isn't going to whiff. 

Could end up being a nice 2-4" or even 3-6" advisory event.

This is looking like 4-8 inch solid low end warning level for NYC in my opinion. 

  • winterwarlock
  • 3,142 posts

 

ID: 266   Posted just now · 

shouldnt we be worried about marginal temps?

i don’t think so all columns are cold ground is cold it’s going to snow. Maybe cape Cod and eastern Montauk winter storm watches should go up tomorrow morning if this holds serve for 4-8

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