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December 2017 Discussions & Observations Thread


Rtd208

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37 minutes ago, Paragon said:

Is this why California is getting unprecedented wet season fires right now?

Yes.

http://weatherwest.com/archives/5982

There has been a tremendous amount of interest—not just within the scientific community, but more broadly among weather-watchers and other drought-weary Californians—in understanding the causes and longevity of the Ridiculously Resilient Ridge. And that turns out to be a genuinely challenging question to answer, despite several years of formal study by quite a few scientists. To date, the strongest evidence appears to implicate unusually warm ocean waters in the tropical western Pacific, which can trigger a hemisphere-scale wave pattern favoring an enhanced subtropical ridge near California.

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Interesting Long Term portion of OKX AFD:

LONG TERM /THURSDAY THROUGH TUESDAY/...
Thu into Fri look quiet, with a weak W-E oriented ridge
extending from the OH Valley to the Mid Atlantic states. Then a
complicated scenario shapes up for late week into the weekend,
as an upper trough amplifies to the west, with potential for
phasing of multiple branches of the upper jet stream as low
pressure passes off to the SE. A combo of the operational
GFS/ECMWF (with support from the GEFS mean) suggests the trough
should amplify enough to bring the core of an associated SW-NE
oriented upper jet streak as far west as NYC, with fairly good
chances for some snow east of there across Long Island and
southern CT with H8 temps below 0C and H8-10 thicknesses below
1290 m. Latest ECMWF shows the core of the upper jet a little
farther west, across northern NJ. So have forecast high chance
PoP from NYC eastward, with most precip in the form of snow as
temps drop close to wet-bulb temps AOB 0C with onset of precip.

All that said, global models often have a SE bias with low tracks in
this scenario, and it would only take a 50-60 mile westward shift to
bring more significant snowfall amounts to the coast, so this
scenario will have to be watched closely. Shortwaves dropping into
the western extent of the longer wave trough across the Mississippi
Valley may help determine the eventual outcome--since they are
dropping southward into the base of the trough, they would be more
likely to reinforce or amplify, rather than kick the offshore low
farther out to sea.

After this low passes east, have forecast slight chance for snow
showers late Sat night into Sunday (except snow/rain showers eastern
Long Island daytime Sunday) as the upper trough to the west swings
across, the fair wx for Mon into Mon night as flow aloft briefly
goes zonal and high pressure passes to the south.

There is potential for a storm to start impacting the area beginning
on Tue, more likely Tue night, as the mean trough to the west
reloads and then significantly amplifies, with both GFS/ECMWF
showing incipient low pressure over the Mid Atlantic region bombing
out as it moves offshore the Mid Atlantic and New England coasts.
Longer range models have advertised this possibility for some time
now, but details are by design sketchy. If the currently advertised
GFS/ECMWF scenario were to pan out, with lack of a strong high to
the NE to supply cold air, this would likely be more of an interior
snow event inland, with rain at the coast. We have a long way to go
to follow model trends with this potential event.

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1 hour ago, bluewave said:

Despite the great blocking coming up especially on the Pacific side, there will be a bit of a lag for the coldest temps. The snow cover fell to near record lows with all the recent warmth. So we'll have to wait until next week to start seeing the -10 or colder daily temperature departures. 

 

multisensor_4km_na_snow_extent_by_year_graph.png.cbcce78a4050caddda4eff9841fe2410.png

 

 

Bluewave, you see how dry the new Euro weeklies are right through week 4? Just continuing the very dry theme we’ve had since September. Sept, Oct and especially Nov were very dry. This may be a red flag coming up: E4082D45-14EF-404A-AFF0-556FFE4F13C0.jpeg    7894D2A7-F681-4740-B7C0-D08648A78715.jpeg7A1B3392-EECA-456A-BD04-F132CF3CC569.jpeg

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11 minutes ago, snowman19 said:

Bluewave, you see how dry the new Euro weeklies are right through week 4? Just continuing the very dry theme we’ve had since September. Sept, Oct and especially Nov were very dry. This may be a red flag coming up: E4082D45-14EF-404A-AFF0-556FFE4F13C0.jpeg    7894D2A7-F681-4740-B7C0-D08648A78715.jpeg7A1B3392-EECA-456A-BD04-F132CF3CC569.jpeg

So you missed the cold in November / posted all fall how warm December / winter would be and now you're on the dry train.

I guess there's guidance to support dry , the problem is once the TPV turns on its side and retrogrades you open up a series window of opportunity.

You just can't look to one piece of guidance and ignore what the rest of packages look like.

You keep making the same errors 

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29 minutes ago, snowman19 said:

Bluewave, you see how dry the new Euro weeklies are right through week 4? Just continuing the very dry theme we’ve had since September. Sept, Oct and especially Nov were very dry. This may be a red flag coming up: E4082D45-14EF-404A-AFF0-556FFE4F13C0.jpeg    7894D2A7-F681-4740-B7C0-D08648A78715.jpeg7A1B3392-EECA-456A-BD04-F132CF3CC569.jpeg

Dry doesn't necessarily mean below average snowfall though. Plus, I feel like many of our dry periods have been punctuated with extreme precip events.

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33 minutes ago, Eduardo said:

Dry doesn't necessarily mean below average snowfall though. Plus, I feel like many of our dry periods have been punctuated with extreme precip events.

In December, if it was wet,  there would be plenty of rainstorms and cutters and it would be mild..You need a dry December for a wintry pattern

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1 hour ago, snowman19 said:

Bluewave, you see how dry the new Euro weeklies are right through week 4? Just continuing the very dry theme we’ve had since September. Sept, Oct and especially Nov were very dry. This may be a red flag coming up: E4082D45-14EF-404A-AFF0-556FFE4F13C0.jpeg    7894D2A7-F681-4740-B7C0-D08648A78715.jpeg7A1B3392-EECA-456A-BD04-F132CF3CC569.jpeg

After week 2, the dry anomalies are fading. By week 4, some wet anomalies show up near the Gulf Coast. This might hint at the possible development of a pattern in which a Miller A-type system could develop.

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7 hours ago, donsutherland1 said:

After week 2, the dry anomalies are fading. By week 4, some wet anomalies show up near the Gulf Coast. This might hint at the possible development of a pattern in which a Miller A-type system could develop.

Yeah. The November Euro Monthlies have some very cold and stormy weather at the Northeast and Mid-Atlantic through Early January.

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