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Jan 4-6 Coastal Bomb

Baroclinic Zone

By Baroclinic Zone,
in New England

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CoastalWx

CoastalWx

Posted
Posted
16 minutes ago, 512high said:

Scott, still days away, should I be following GFS now or that is still garbage till 24 hours before event?

I would not toss any model really. Perhaps the better way of saying this is to not put as much weight into some models. The non-hydrostatic (meso models) as Will said last night are still in the early stages of being used...and have their normal amped up biases. But as we head through the day into the overnight..if they still are near the benchmark and the globals head that way...I might put more stock in them.

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40/70 Benchmark

40/70 Benchmark

Posted
Posted
38 minutes ago, Hoth said:

I dunno, that little sucker last winter was in and out faster than this and there were widespread 14-17" reports. This is gonna be juiced and more intense. Jan '11 was a quick hitter too and I pulled 27". We'll see, I suppose. Every system is different.

Like I said...just not ready to toss those numbers around YET...lol

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dendrite

dendrite

Posted
Posted
8 minutes ago, Baroclinic Zone said:

I'm definitely going to put some credence into the "juicer" hydrostatic runs starting today.  We've seen the Euro and GFS bumping up their output overnight and I think we see it continue today.

I think you mean the nonhydrostatic models.

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512high

512high

Posted
Posted
9 minutes ago, CoastalWx said:

I would not toss any model really. Perhaps the better way of saying this is to not put as much weight into some models. The non-hydrostatic (meso models) as Will said last night are still in the early stages of being used...and have their normal amped up biases. But as we head through the day into the overnight..if they still are near the benchmark and the globals head that way...I might put more stock in them.

ty scott

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RUNNAWAYICEBERG

RUNNAWAYICEBERG

Posted
Posted
9 minutes ago, WinterWolf said:

Let's hope we see a few more ticks west today...so us Central and Western peeps can join in the fun too....

 

7 minutes ago, moneypitmike said:

this.  not biting yet.

I actually think we are close enough to the nw deform band zone. Like even though ECT has more qpf, its a general smoothing of the precip shield by models that usually ends up more unevenly distributed in reality. 

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Baroclinic Zone

Baroclinic Zone

Posted
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Posted
Just now, Damage In Tolland said:

Sippy all over it

 

Quote 

.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
Highlights...

* Potent coastal storm will bring accumulating snowfall, gusty winds
  and coastal flooding concerns on Thursday.
* Cold Arctic airmass will filter back into the region this weekend.
* Southern stream system approaches early next week.

Pattern Overview/Confidence...

An active period to start the medium range with approaching system
for the Thursday timeframe. Longwave trough will turn negatively
tilted on Thursday as coastal low moving up from the Bahamas passing
just east of the 40N/70W benchmark as the system undergoes rapid
cyclogenesis. Once this low pressure system moves up into the
Maritimes, persistent NW flow will remain as longwave trough brings
in anomolous cold air nearing 3 STD below normal. Flow will become
more zonal as southern stream wave will develop a system out of the
Rockies by early next week. This will help warm the region back to
normal with Tuesday or Wed being the next chance for precip.

Details...

Wednesday night into Thursday night...Moderate confidence.

* Accumulating snowfall event for eastern half of the region
* Strong gusty winds for the Cape and Islands
* Coastal flooding issues for east MA Coastline

Overview...

Guidance is in general agreement with the upcoming system on
Thursday. However, there are still some settled differences which
could result in more or less snowfall. Currently, potent shortwave
moving into the Rockies will be the focus for our system as it dives
along the base of the elongated trough. Tropical moisture around the
Bahamas will eventually become our surface low in the coming day as
it gets picked up from the shortwave and moves up the coast towards
New England. This trough will eventually become negative as the
surface low undergoes rapid intensification and bombs out just east
of the 40N/70W benchmark.

This coastal low will be quite potent, with many models suggesting a
pressure dropping to 960mb or lower. As a result, both winds and any
precip from this system will extend far from the center resulting in
effects from the storm for much of the region.

Models...

Generally the 00z model guidance is in agreement with this system.
However the 00z GFS appears to be on the eastern end of the envelope
with both wind and QPF. Thus trended the forecast toward WPC/EPS/GEFS
and UKMET to account for latest trends in this system, which is a
bit more wet than 12z. This resulted in a bit more QPF and stronger
winds for this forecast. Latest 06z NAM has trended a bit farther
west and push the 850mb low right over the benchmark. Hopefully this
is not a trend or else will need to expand all watches farther west.

Snow...

As mentioned above, trended away from the GFS and towards UKMET, EPS
and WPC. This with have about 0.5 inches of QPF along the I-95
corridor with and inch of QPF just east of the Canal. Farther north
and west will have less QPF with perhaps 0.1 inches. However, that
region will see a very cool airmass increasing the snow ratios as
well as some omega lift per NAM and GFS.

One thing to fine tune is the locution of the coastal front. Would
like to have hi-res guidance to have a better idea, but appears that
the front will be just west of the Canal with this forecast. Thus
expect the higher snowfall amounts to be just west of where the
coastal front sets up, across the SE coastal plain of MA . With the
increase in QPF and a bit higher snowfall ratios, we could see
around 4-8 inches of snowfall across the eastern half of the region.
May have to watch for a good F-gen band in conjunction with the
coastal front, which could increase snowfall rates. In fact, the
latest SREF guidance shows 30-40 percent probs of snowfall rates
near 2 inch an hour.

The Cape and MA islands will have thermal issues as they will be
closes to the low which could help bring in warmer temps keeping
their p-types as rain. However as the storm pulls away, temps will
quickly fall and any rain will change to snow on the backside of the
system.

Overall went ahead and issued a watch where confidence was the
highest for snowfall above 5.5 inches. Would not be surprised if
this watch gets expanded during the day especially for Northeast MA.

Wind...

Strong pressure gradient from this system will result in 925mb winds
to increase around 45-55 kts. While BUFKIT and model lapse rates
show that some of the wind may struggle to fully mix down to the
surface, we could still see some very strong gusts, especially along
the coastline. It not every day the conservative EC is showing above
50 kts for ACK. These winds could be enhanced by strong pressure
couplet moving through the region. Confidence is not as high to
issue any winds headlines at this time, but it is something to keep
an eye on especially if snow continues to fall. Blowing and drifting
snow may result in a hazard especially during the evening commute.

Coastal Flooding...
Please see coastal flooding section below.

Overall a multi-complex storm moving into the region on Thursday.
This is a strong system which will result in multi-hazards. Since we
are still over 2 days away things can still change. For now went
with were confidence was highest on seeing 6+ inches of snow. Fully
expect conditions to change and hazards to be expanded over the next
24 hours.

 

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SlantStickers Anonymous

SlantStickers Anonymous

Posted
Posted
1 minute ago, RUNNAWAYICEBERG said:

Nam is crappy with run of the mill systems but it is useful in big events, imo. If it’s on its own, then its tossed but if it has support from rgem and the likes....

The whole meso team can be on board with one solution and it still wouldn't mean much unless we're under 48hrs away from the event IMO. 

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