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January 2019 Discussion II


Typhoon Tip
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1 minute ago, RUNNAWAYICEBERG said:

Valid concerns. My focus has been on #1. Even if the Fri clipper is further north, if we can hang back the Sun energy some more initially, it can offset it. 

But I agree. It’s not this simple vodoo of “the PV will push this colder”. 

Stronger system Friday, as long as it doesn't get too amped should help our cause.

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5 minutes ago, HIPPYVALLEY said:

Winter season you and I are closer to CNE then SNE wrt set ups like this and how this board interprets sensible winter wx forecasts.  N of RT 2 and W of I-290 is really part of CNE in Winter.

You’re gonna get crushed bud. No sucking on exhaust with this qpf glob. Have a lot of wiggle room too so just sit back, open your arms, and smile.

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Just now, dendrite said:

Pretty clear shot of the brief PV relaxation there. Better ridging out west is letting that trough dig and amplify more too.

Yeah, if you just sit there and watch the progression for a bit you can see a lot of different factors at play.  That building PNA ridge is actually hurting this storm potential right now as modeled.

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3 minutes ago, Baroclinic Zone said:

I do see some positives in the gif I posted.  While the PAC side does not look great to me on the trend, you can see the North Atlantic developing a -NAO building south which could make this storm move more easterly if that region can continue to do so.

That ridging is practically over Ireland.

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Real talk for a moment......did Tippy write the long range BOX AFD?

Looks colder, stormy. Continued poleward sub-tropical contributions
per potential temperature along the dynamic tropopause, lately over
the N Pacific where volatility / robust classical storm development
has ushered warm air, higher heights N of Alaska, beginning to down-
shear N-stream energy over N America, potential vorticity anomalies,
deeper tropospheric folds. Pattern maintains within 5-day average H5
height ensemble means out through early February with a deep E CONUS
H5 trof, negative H85 temperature anomalies.

But other noteworthy signals: 1.) Possible downstream traffic build-
up, S Greenland H5 ridging, slowing the upstream pattern at one
point or another, 2.) How and if the split 50-10 mb polar vortex
plays a role, 3.) A forecast re-emerging MJO, phase 4 to 7 for late
January, that climatologicaly would contribute to a warmer E CONUS
in part due to potential E propagation of sub-tropical Pacific low-
level wind anomalies from a weak +ENSO to the CONUS, and 4.) The EC-
control continuing to signal strong -AO / -NAO teleconnections for
the start of February.

Lots of uncertainty, unknowns. Seemingly there`s greater opportunity
for deeper storm development in vicinity of New England given the H5
pattern noted above. But reiterating ... cascading gyres equatorward
undergoing perturbations, amplification, interactions yield abundant
potential outcomes difficult to nail down with certainty. To put it
simply, would not expect deterministic forecast models to coalesce
and corroborate upon details more precisely until we are closing in
on the system, perhaps not until we see the whites of its eyes.

Break down details, forecast thinking in the discussion below. Low
confidence forecast starting with Friday. Greater weighting towards
EC / ECens.

*/ Discussion ...

Wednesday through Thursday...

Sweeping cold front late Wednesday into Wednesday night. Attendant
continental-polar airmass, mainly a dry passage but can`t rule out
the squeeze of some snow shower / flurry activity across the high
terrain of the Berkshires. Cold air advection into Thursday morning
as winds turning light under mostly clear conditions. While mainly
seasonable Wednesday, colder Thursday with morning lows around the
single digits forecast.

Thursday night through Friday...

Snow chagning to rain. Isentropic upslope along 280-290K surfaces.
Precipitable waters up to 0.75 inches. Along an open-wave trof axis,
maybe spurring secondary low development if 14.12z GFS is correct,
front boundaries sweep through providing ample lift beneath weaker
ascent. Anticipating light outcomes, onset snow Thursday night then
changing to rain. Onset cold quickly eroding as synoptics do not
support cold air drainage / maintenance of Thursday`s Arctic air-
mass. Maintaining ice within the column, no precip-type issues, will
see snow gradually change over to rain with S winds prevailing, warm
air ushered N, change over mainly during daylight hours. Thinking a
coating to 2 inches, locally higher over the Berkshires, before it
erodes and/or melts away. Potential Friday AM commute impacts.

Got to watch trends on the attendant shortwave whether if it becomes
amplified or not, invoking a secondary low. If that be the case,
could see greater outcomes given stronger ascent through the column.

Friday night through Saturday...

Canadian high pressure carves S. Conditions clear out. Cold air
advection proceeds. Arctic air slips back across the region. Dry.

Saturday night through Sunday night...

A frontal wave, and with that, inherant challenges in regards to the
juxtaposition of weak synoptic fields, thermal gradient, and overall
outcomes. Wiggles, perturbations, etc., considerable challenges with
the forecast. A consensus, heavily weighted with ensemble means, has
the weak low center sweeping W to E Just S-offshore of New England.
Hardly a closed low above H85, moist-stream focused within the anti-
cyclonic warm conveyor belt. One big Baroclinic Leaf with a SW-NE
dividing line at the surface between liquid and frozen precip-types,
a likely mix in-between given a weak element of pull back of the
conveyor belt motions beneath lower heights associated with the
positively-tilted trof axis, a warm-air intrusion up around H8. A
shift N, a shift S, the spread among guiance, it`ll be awhile before
we can really nail down exact and specific outcomes. Low confidence
forecast.
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45 minutes ago, RUNNAWAYICEBERG said:

You’re gonna get crushed bud. No sucking on exhaust with this qpf glob. Have a lot of wiggle room too so just sit back, open your arms, and smile.


Yeah, barring major NW trends, RT 2 corridor and N is getting a whole lot of frozen precipitation.  Of course we would prefer it to be mostly snow but so far even the biggest debbies have not been concerned with paltry QPF from this one. 

 

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