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Big Snow threat, what will it do, part II


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No one is solely focusing on QPF - the forcing is disjointed as we've been mentioning. Not all storms have to put CT in the jackpot... compared to the rest of SNE we are in the worst spot. Not sure why that's hard to understand. 

The way you are posting woukd make someone think Ct might only get a few inches..so just wondering

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Not directly storm related---but not the usual sps

 

...PROLONGED COLD LATER THIS WEEK... ARCTIC AIR WILL LINGER ACROSS SOUTHERN NEW ENGLAND INTO THIS WEEKEND...WITH THE COLDEST AIR YET TO ARRIVE FRIDAY INTO SATURDAY. MANY LOCATIONS WILL SEE WELL BELOW NORMAL TEMPERATURES FROM NOW UNTIL SUNDAY OR MONDAY. THIS PROLONGED COLD MAY LEAD TO FROZEN WATER PIPES...INCLUDING FIRE SPRINKLER SYSTEMS...AND POTENTIAL PROPERTY DAMAGE. THIS MAY BE ESPECIALLY TRUE IN BUILDINGS WHERE THE HEAT HAS BEEN TURNED DOWN TO CONSERVE ENERGY DURING THIS HOLIDAY PERIOD. IN ADDITION...PLEASE BE WARY OF PORTABLE HEATING DEVICES. THESE CAN OVERHEAT IF NOT USED PROPERLY...INCREASING THE RISK OF FIRES.

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windy on the outer cape also, will the B word verify there?

 

 

I wouldn't be shocked if blizzard headlines were put up on the Cape at some point...esp if this main vort can bring the low closer...increased wind and heavy snow will make it an easy call there I would think if the trend continues. Heck even now, it might be close to 50/50...I'd just like to see the rates pick up to ensure 1/4 mile vis if I was contemplating a blizzard watch there. But its something that I wouldn't be surprised at.

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Nice write up from BOX.. Good storm for everyone.

 

* MODELS...MOST OF THE MODEL SUITE IN RATHER GOOD AGREEMENT WITH THE
DEVELOPMENT OF THE LOW...OR EVEN SEVERAL WAVES OF LOW PRES WELL S
OF NEW ENGLAND...KEEPING SOME W-E PROGRESSION BUT HOLDING IN PLACE
THROUGH THIS TIMEFRAME. WITH THE HIGH SET UP OVER QUEBEC/N
MAINE...THIS KICKS UP THE ONSHORE FETCH OF LL MOISTURE. 00Z
ECMWF/12Z GFS ALONG WITH THEIR ENSEMBLES AND NOW...EVEN THE 12Z
UKMET...SETTING UP E-W SURFACE TROUGH. ALSO NOTING EXCELLENT 925-
850 HPA FGEN FORCING SETTING UP THU NIGHT ACROSS NE CT/RI/SE MA
WHICH WILL ONLY ENHANCE LIFT.
STILL SOME SPREAD AMONGST THE GEFS
ENSEMBLE MEMBERS...THOUGH NOT QUITE AS MUCH AS SEEN IN EARLIER
RUNS. BEST AGREEMENT AND CONSISTENCY REMAINS WITH THE 00Z ECMWF/
12Z GFS AND THEIR ENSEMBLES. AVERAGE CONFIDENCE FORECAST.



* SNOW...EXPECTING ALL SNOW FOR PTYPE WITH ARCTIC AIR IN PLACE ONLY
TURNING COLDER THU NIGHT AND FRI. H925 TEMPS RANGING BETWEEN -8C
TO -13C ACROSS THE AREA THU NIGHT THEN WILL DROP FURTHER FRI.
WITH DEEP LOW AND MID LEVEL MOISTURE ALONG WITH THE DEEP COLD
AIRMASS OVER THE REGION...EXPECTING HIGH SNOW TO WATER RATIOS ON
ORDER OF 15-20 TO ONE...YIELDING A POWDERY SNOW FOR MOST AREAS.
MAY BE A BIT LOWER ALONG THE IMMEDIATE E COAST WITH THE ONSHORE
WINDS. USED A BLEND OF THE PREVIOUS FORECAST AND GFS FOR QPF
FORECAST. LOOKS TO BE AROUND 0.3 TO 0.4 INCHES FOR MOST AREAS THU
NIGHT INTO EARLY FRI ALONE...WITH TOTAL OF 0.6 TO 0.8 INCHES
THROUGH THE EVEN
T. THEN...WITH THE NE WINDS BECOMING N...COULD SEE
MORE OCEAN EFFECT SNOWS LINGERING ALONG THE IMMEDIATE COAST MAINLY
OVER THE CAPE AND ISLANDS DURING FRIDAY. A BIT MORE CONFIDENCE ON
QPF AND SNOW TOTALS BUT STILL SOME TIME FOR ADJUSTMENTS IN TRACK
AND AMOUNTS.

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I wouldn't be shocked if blizzard headlines were put up on the Cape at some point...esp if this main vort can bring the low closer...increased wind and heavy snow will make it an easy call there I would think if the trend continues. Heck even now, it might be close to 50/50...I'd just like to see the rates pick up to ensure 1/4 mile vis if I was contemplating a blizzard watch there. But its something that I wouldn't be surprised at.

 

Didn't they used to have a temp element to the blizzard definition?   This one would benefit with that in the mix.

 

15.8/12, off a high of 17.1.  Not too shabby.

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Partially storm related...but the cold on Friday is pretty anomalous. MEX guidance 3 days out (so climo is def playing a part here) has a high at ORH of 6F. That would be the coldest high temp since January 2004.

 

The 2M temps are wild as well. Keeps some of the NW hills towns in CT sub-zero all day!

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Not directly storm related---but not the usual sps

...PROLONGED COLD LATER THIS WEEK... ARCTIC AIR WILL LINGER ACROSS SOUTHERN NEW ENGLAND INTO THIS WEEKEND...WITH THE COLDEST AIR YET TO ARRIVE FRIDAY INTO SATURDAY. MANY LOCATIONS WILL SEE WELL BELOW NORMAL TEMPERATURES FROM NOW UNTIL SUNDAY OR MONDAY. THIS PROLONGED COLD MAY LEAD TO FROZEN WATER PIPES...INCLUDING FIRE SPRINKLER SYSTEMS...AND POTENTIAL PROPERTY DAMAGE. THIS MAY BE ESPECIALLY TRUE IN BUILDINGS WHERE THE HEAT HAS BEEN TURNED DOWN TO CONSERVE ENERGY DURING THIS HOLIDAY PERIOD. IN ADDITION...PLEASE BE WARY OF PORTABLE HEATING DEVICES. THESE CAN OVERHEAT IF NOT USED PROPERLY...INCREASING THE RISK OF FIRES.

This goes into my responsibility and line of business and why I am always here trying to stay two steps ahead of the weather, protecting 1/2 billion in assets does that, I cranked the heat up in all my building areas before we left for a four day weekend thinking about the cold and the fact we could be home Thursday, have to hedge all the time, saving a couple of bucks on energy and paying hundreds of thousands of dollars in water damage does not make sense. I totally err on the side of caution this time of the year.
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I was reading about the Euro's 4-D variable system and it's fascinating how it has these correction schemes for smoothing out noise.  The GFS cluster does not avail of that system.  It would be meaningless if it did, anyway, because the GFS grid is too coarse to avail of those schemes.  I recall an experiment I read about 3 years ago, where they took the ECMWF initialization and fed it to the GFS, and it improved immediately in a single run/reanalysis.  Anyway, if the GFS assimilations create randomness, it could be why there are noticeable differences in system handling upon coming on shore.  Same with the NAM (maybe).   I dunno, but I am looking at a 60 hour NAM trough structure and amplitude on the 18z, and it is significantly different enough compared to the 66 hour 12z that SOMEthing has to account for the increased amplitude (and no, I am not part of the NAM-auto-sucks group, though I agree it's has fewer stellar moments).  I mean, voriticity advection improved dramatically, and there are hints of more s/w ridging rippling out ahead.. .

Say what?  First of all, little known fact that the GFS analysis resolution is actually HIGHER than the ECMWF analysis resolution (the analysis increment is done on a grid roughly 2x the ECMWF grid I think).  This is because 4DVAR is so much more expensive than the Hybrid 3D EnVar system that is used in the GFS/GDAS. 

 

What exactly did you read and what are you referring to?  The GDAS system also has many noise/smoothing constraints within it, including an incremental normal mode initialization technique.  I'm happy to pass you a reference if you're interested.  Now, given that the NCEP system is still 3D, there are issues, such as treating the observations at their correct time, extracting tendency information from the observations etc.  NCEP is working aggressively to implement a 4D variant for the GDAS....not the uber expensive 4DVar that requires the tangent-linear and adjoint models, iteratively as part of its solver, but instead an extension to the current operational hybrid called 4D EnVar.  Preliminary results are extremely encouraging.

 

Lastly, in terms of the impact experiments you cite, they aren't particularly meaningful.  Data assimilation is performed incrementally, so by attempting to drop the ECMWF analysis into the GFS model, you are actually injecting features from the ECMWF model itself.  NCEP has yet to glean anything meaningful and practically relevant about the operational system from such injection experiments.

 

I'm happy to have a discussion on the merits of 4DVAR, EnKF, and hybrid variants, as well as a provide my opinion on the cost-benefit analysis if you are interested in learning more.

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http://www.weather.com/news/weather-winter/winter-storm-hercules-forecast-20131231

 

What a Flipping BS Hype Machine.  For YEARS since I was a kid the Weather Channel was The Single Most Conservative source there was.  Even remember 1" - 3" about 24 hours before Dec. 9th, 2005 specifically.  

 

But Big blobs of 12-18????  And the random one in Worcester?  These guys have turned into "Total Whores" as our good friend _ _ _ _  _ _ _ _ _  says.    

 

EDIT: The OTHER super conservative source was Accuweather.  For this storm, I've been in the 12"+ shading for days.  

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