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December 2022 Obs/Disc


40/70 Benchmark
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33 minutes ago, Euler_1 said:

I'm supposed to drive from NYC to southern VT on Friday.  Looks like I should change my plans.  Do you all think that trip on Friday will be a nightmare of rain and wind?

If it were me, I'd leave early. Rain and wind, no problem... but I'm sure you know how long it takes to get treatment on the highways up there. They won't be able to pre treat either with the rain

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On 11/22/2022 at 9:45 AM, 40/70 Benchmark said:

I think the main deviation from what I had expected for the month of December when I issued my outlook a couple of weeks ago is that the neg NAO looks a bit more pronounced, which turns this:

cd146.243.205.193.325.7.23.58.prcp.png

cfs-mon_01_T2ma_us_1.png

Into this:

NOcfs-mon_01_T2ma_us_1.png

Note how the more pronounced high latitude blocking earlier in the season helps to relegate any semblance of a se ridge to the southern mid Atlantic, as compared to modest positive anomalies encroaching on the NE in the aforementioned guidance and seasonal forecast composite.

While the month appears as though it may be trending a bit cooler due to what may transpire at higher latitudes, all is not lost if this does indeed revert back to a slightly tamer look. The month should not end up as mild as it could otherwise due to the tendency for Canada to remain cold, a la the 1973, 1975 and 2007 dataset mentioned on the seasonal forecast, which will ensure chances for wintery weather during the month across the north, despite the fact that it will not be a frigid month. The month will gradually turn colder as the high latitudes become more disturbed, and while the mid-Atlantic may find snowfall scare, New England should not...especially north and interior. However, coastal areas/lower terrain may have frequent precip type issues during coast storms due warm SSTs. Some elevation events are certainly possible. There will also be southwest flow events/warm air advection events, which will be more fruitful for the coast in terms of snow. A white Christmas is likely across the interior and northern New England, and possible along coastal southern New England. It is very unlikely for at least the lower terrain of the mid Atlantnic.
 
While this is not your prototypical "big dog pattern", they are possible should a worthy wave become pinned beneath the NAO block, a la Jan 2011. Said system would be of the miller B variety and primarily impact from the 40th parallel on north.
December Forecast H5 Composite:
 
AVvXsEjJ9AvFHOufuLHOlwOQLkGxNYH_a7Bm4-o4
 
image.png.25a6412cd2be7abd4e1616d15f5dd868.png
 
 
The real fireworks may come after the new year.

I think the initial post of this thread just about exactly one month ago captured it pretty well....hopefully things work out next month.

I am surprised that the coast couldn't even muster one noteworthy snowfall from a SWFE...I didn't think it would be that shitty, but that is some bad luck mixed in. The mean H5 pattern certainly doesn't scream "virtually snowless in Boston".

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22 minutes ago, HoarfrostHubb said:

That looks real.  Not sure what office... Buffalo area?

Yeah that's BUF. They're still going wild.

.LONG TERM /FRIDAY THROUGH TUESDAY/...
...Once in a Generation Winter Storm to Slam the Region Heading into
and THROUGH the Christmas Weekend...

Old Man Winter will unleash the full fury of winter upon our region
during this period...as an extremely amplified longwave pattern will
spawn one of the most intense storm systems in decades to impact the
Mid West and Great Lakes region. This system will likely end up
setting low pressure records once it passes north of the border and
will have the potential to generate at LEAST storm force winds over
the Lower Great lakes.

As if the very real threat for damaging winds of 60-70 mph were not
enough...there will also be the risk for a prolonged...paralyzing
heavy lake effect snow event. The very strong to damaging winds,
blowing and drifting snow with localized blizzard conditions
preceded by a rapid flash freeze all coming right before the
Christmas holiday weekend resulted in a *long duration* winter storm
watch being issued for western NY. A Winter Storm Watch has also now
been issued for Jefferson and Lewis county from midday Friday
through Monday. While heavy lake effect snows have already occurred
this winter season...this will be the first event with multiple
impacts from such intense winds. Winter storm watches are already in
effect for parts of western New York with the high component wrapped
into the same product.

An extremely amplified longwave pattern during this period will
spawn one of the most intense storm systems in decades to impact the
Mid West and Great Lakes region. This system will likely end up
setting low pressure records once it passes north of the border and
will have the potential to generate storm force winds over the Lower
Great lakes.

Explosive cyclogenesis will take place over the mid western states
into southern Ontario on Friday...as an anomalously strong 150kt H25
jet will pass through the base of a very deep longwave trough. This
will support rapid deepening of a corresponding sfc low that will
track southern Ontario by late Friday. The `bombing` low will deepen
from roughly 990mb in the vcnty of Lake Erie/Lower Michigan late
Thursday night...to 982mb over southernmost Ontario Friday morning
to about 968mb near the Ontario-Quebec border by Friday evening...
easily meeting the definition of bombogenesis (24mb/24hrs). Such
deepening is relatively rare in the LOWER Great lakes...but more
common across the UPPER Great Lakes and certainly with Nor`easters
along the coast. Some of the parameters of this intense storm are
climatologically `off the charts`...such as MSLP and strength of
both the low level and upper level jets. One could certainly
describe this storm system as a once in a generation type of event.
Subtle differences remain...but there remains general model
agreement in the overall large scale scenario...which adds
confidence.

The rapidly intensifying low is forecast to pass just to our west on
Friday. Winds will ramp up in the cold air advection and during when
max pressure rise/fall couplet crosses. This is about as good as it
gets in terms of maximizing winds/gusts to the sfc. Several guidance
packages are now advertising wind gusts over the IAG Frontier to
near 60 mph late in the day as another intense 70kt LLJ enters the
region. This is NOT when the strongest winds are expected though.
That is yet to come.

In regards to pcpn on Friday...the strong winds will open the door
for MUCH colder air to pour across our forecast area. This will
result in a RAPID change over of the rain to snow with deep
frontogenetic forcing leading to a burst of moderately heavy snow
that will yield accumulations of several inches expected by late
afternoon. Temperatures that will start the day in the low to mid
40s in most areas will PLUMMET into the single digits across the
Srn Tier by the end of the day...while readings will range from the
teens across the remainder of wrn NY to the lower 30s east of Lake
Ontario. This dramatic plunge in temperatures will likely result in
a flash freeze of the snow/water/slush.

As the extremely deep storm system further deepens in place over the
Ontario-Quebec border Friday night...a strong secondary cold
front/sfc trough will plow across our forecast area. This will be
accompanied by the second 70kt low level jet that...being found in
the cold sector...should largely mix to the sfc at times. The threat
for high winds at the sfc will be greatest in the typical corridor
from Lake Erie and the IAG Frontier to Rochester and then to the
Thousand Island region. Increased winds some in these corridors.
Power outages will be a concern as will be blowing snow and drifting
snow.

The widespread synoptic snow during the first half of Friday night
should then taper off as the deepest forcing exits and limited
drying arrives in the mid levels. Meanwhile...a 230-240 flow of -20c
H85 air will promote an area of lake snow to become established
Buffalo northward...across IAG and the Northtowns. The snow...
whether it be synoptic or lake induced in nature...will be blown
around by +50 mph winds so significant blowing and drifting can be
anticipated along with near zero visibility and at least localized
blizzard conditions. As is typically the case...the very strong
southwest flow will also shove a great deal of water up to the
Buffalo end of Lk Erie...so lakeshore flooding will be a
possibility. More specifics on that in the lakeshore flooding
discussion.

A very tight sfc pressure gradient will remain in place across our
forecast area on the day before Christmas...so while the winds
should diminish as bit by way of a weaker LLJ especially later in
the day, they will still be strong enough to possibly cause issues
and certainly to support continued blowing snow. Models have trended
a bit quicker with veering of winds, to more of 240-250 flow so that
more of the Buffalo Metro would be impacted by lake snows Saturday
into Saturday night with the visibility remaining near zero at times
within the band. It will be quite cold with Saturdays highs ranging
from the single digits over the Srn Tier to the teens and low 20s
elsewhere resulting wind chills falling to as low as 10 to 20
degrees below zero.

Christmas Day promises to remain cold with highs only in the teens
to low 20s and winds to 30 mph generating wind chills of 10 below to
just a few degrees abv zero. Meanwhile...a 240-250 flow will keep
the lake snow machine in full gear for sites near and just south of
the Buffalo and Watertown areas. No big change to forecast thinking.

While the very cold weather will persist into Monday...sfc based
ridging should help to at least lessen the potential for additional
significant lake snows later Monday into Tuesday. Possible that
conditions moderate more significantly by middle of next week, but
not surprisingly, not a clear signal yet.

 

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14 hours ago, Baroclinic Zone said:

I want the royalties! :sled:

When nothing comes in December: What do you want? It’s not even Winter yet. 
When nothing comes in January: Well, you know, the January thaw.    
When nothing comes in February: Be patient, the pattern is reloading!
When nothing comes in March: What do you expect, it’s almost Spring!
 

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8 hours ago, jbenedet said:

Speaking for SNE - the lack of snow during this window from 12/1 to say 1/15, is most disappointing in terms of building a sustainable pack. Peak climo is later, sure, but the Solstice really does a lot to minimize pack reduction--it's difficult to overstate. 

It gets increasingly more difficult to see that happening, anyway.   Just being candid -

I mean, we get these incursions that jolt a cold dagger, ...but, 582 hgt to ALB less than a week later? 

5     8      2

That's a whack anomaly for ending Decs.  Seeing 588 creeping up the lower M/A on some ensembles, too, is really an "attributable" offense imho.   That beauty of being completely irreverent to mores in the matter such that I am, I don't give a shit if offends people.   We bake and go DISproportionately above climo, compared to however far this goes below.  Anything to make sure the longer term continues to climb against climate, appears to be the return routine.  I was talking to John today... this is the way.   We don't roast to 108 around here in the summer.   We do it with low temperatures at that time of year.  What we do here, is we own the world at winter screwing warmth.  

3 Februaries out of the last 6 years were 80+ at some point during, over SNE.   I'm sure it's happened abroad ...but we've been +30 to +40F high temperatures in recent winters, three times.   I'm like... really

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14 hours ago, Typhoon Tip said:

It gets increasingly more difficult to see that happening, anyway.   Just being candid -

I mean, we get these incursions that jolt a cold dagger, ...but, 582 hgt to ALB less than a week later? 

5     8      2

That's a whack anomaly for ending Decs.  Seeing 588 creeping up the lower M/A on some ensembles, too, is really an "attributable" offense imho.   That beauty of being completely irreverent to mores in the matter such that I am, I don't give a shit if offends people.   We bake and go DISproportionately above climo, compared to however far this goes below.  Anything to make sure the longer term continues to climb against climate, appears to be the return routine.  I was talking to John today... this is the way.   We don't roast to 108 around here in the summer.   We do it with low temperatures at that time of year.  What we do here, is we own the world at winter screwing warmth.  

3 Februaries out of the last 6 years were 80+ at some point during, over SNE.   I'm sure it's happened abroad ...but we've been +30 to +40F high temperatures in recent winters, three times.   I'm like... really

I'll still take that if it results in more 30"ers that pork me with 13". I'll gladly trade a few 6"ers that leave me with 3".

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