Feb 22nd/23rd "There's no way..." Obs Thread

[mitchnick]

17 minutes ago, RDM said:

Based on NWS radar loop, it appears to be snowing along the M/D already - although it could be virga.  Precip field has really blossomed the last couple of hours.  

I woke up at 2 and have been waiting to see precip type, but all virga in Hanover, PA so far. Not so sure I start as snow, in fact, I doubt it.

[mitchnick]

6z Nam twins aggressive with getting all snow in by 10-11am. 

[mitchnick]

6z Nam atv7pm

[mitchnick]

6z Nams looked better at first, but the slp moves out a little faster so accumulations are reduced from 0z in many places. Always something. 

[MDstorm]

16 minutes ago, mitchnick said:

6z Nam atv7pm

  Only up to 7pm??  That’s basically what Euro has for my area for the entire storm.

[Ji]

6z Nams looked better at first, but the slp moves out a little faster so accumulations are reduced from 0z in many places. Always something. 

Moron lol what am i missing here
?

[RDM]

36F with rn/sn mix.  Some fatties mixing in but not many atm.  Lots of moisture in the fetch running across the SE into the GOM. 

[RDM]

3 minutes ago, Ji said:

Moron lol what am i missing here
?

If only that 12k were to validate...  Most of the forum would be happy campers.  NJ and NYC would be shut down for a long time.   

 

 

[Ji]

36F with rn/sn mix.  Some fatties mixing in but not many atm.  Lots of moisture in the fetch running across the SE into the GOM. 

Where do you live?

[mitchnick]

21 minutes ago, Ji said:

Moron lol what am i missing here
?

Moron, Pivotal maps are different and I said "some places COMPARED TO 0Z."  Why have you become the belligerent jerk? You act like a hungry, tired child. Grow up.

[Ji]

Moron, Pivotal maps are different and I said "some places COMPARED TO 0Z."  Why have you become the belligerent jerk? You act like a hungry, tired child. Grow up.

Stop cherry picking negative things just to incite the board

That’s something a bored troll would do. Really fv3??

[arlwx12]

Snip of the 320 LWX AFD...

As of 315am, light snow has been observed over the Alleghenies with
light to moderate pockets of shower/drizzle over the Shenandoah
Valley. Elsewhere, cloud cover continues to increase with some virga
as the atmospheric profile begins to moisten with large scale ascent
ahead of the approaching upper level trough. Precipitation should
begin as a mixture of light rain and snow for most, with all snow
above around 1500 feet. Expect precipitation to remain relatively
light through mid to late morning then turning steadier later this
afternoon as the main lift from the trough/coastal low move
overhead.

Surface temperatures will initially be in the mid to upper 30s at
lower elevations, and should hold in the mid 30s through mid-late
afternoon (prior to 6pm). As a result, much of the region will
experience several hours of mixed rain and snow "white rain" that
won`t accumulate and will largely be unimpactful other than making
for wet roads. However, snow will accumulate across the higher
elevations (i.e Catoctins, Alleghenies, and crest of the Blue
Ridge) above 1500 feet throughout the day.

Temperatures will gradually fall later this afternoon and evening as
dynamical cooling ensue from the approaching coastal low and upper
level trough. The large scale ascent from these features will allow
the atmospheric column to cool allowing for the rain/snow mix to
transition over to all snow across the forecast region. Temperatures
will fall from the mid 30s into the upper 20s and low 30s during
this time as the heaviest precipitation moves in Ratios will also
climb during this time with 1:1-5:1 ratios outside of the
elevations above 1500 feet during the day climbing to 8:1 to
13:1 overnight into Monday morning. Either way expect a wet
character to the snow given the high liquid equivalent. This
will make it hard to pick up with a shovel (heart attack snow)
compared to pushing with a plow or removing with a snow blower.

The greatest impact from snow locally is expected later this evening
through predawn Monday morning as the coastal low tracks off the
Delmarva and the upper axis trough moves overhead. Expect two areas
of enhanced snowfall: one with the coastal low that will encompass
the western shore of the bay up into the northeast/central MD and
another with the inverted trough (or norlun trough) across the
Catoctin/Potomac Highlands. In addition to this expect heavy upslope
snow/squalls over the Alleghenies given strong north/northwest flow.

The first area of enhanced snowfall rates will be close to
Chesapeake Bay, where mid- level frontogenetic forcing to northwest
of the coastal low will be strongest. Uncertainty remains in how far
west this area of heavier snow gets, but most solutions show it only
impacting the counties immediately adjacent to Chesapeake Bay in our
forecast area (St.Mary`s northward through Cecil). Snowfall rates
could approach an 1-2 inches per hour at times in this area between
roughly 7 PM and 3 AM. Near blizzard conditions are also possible
with gales over the waters and gusts in excess of 30-40 mph.

The second area of enhanced snowfall rates will be along an inverted
trough axis (sometimes referred to as a Norlun trough) that will
extend north to south through north-central portions of the forecast
area. Dynamically, this will occur along a low-level trough axis (in
the 900-700 hPa layer) where northeasterly winds in response to the
developing coastal low offshore converge with northwesterly winds
advancing beneath the upper trough. Model guidance remains in good
agreement that such a feature will occur, but there is still some
uncertainty with respect to the positioning. 00z CAMS have trended
slightly west with this features extending from Washington/Frederick
counties down through Jefferson/Loudoun/Fauquier counties. Such
features typically are very, very narrow in width (likely only 10-20
miles from west to east), and are notorious for producing very heavy
snowfall rates. Most guidance shows hourly QPF values of around 0.2-
0.4 inches, which would translate to 1-2 inches per hour of snow.
This feature will likely be either stationary or very slow moving
over several hours tomorrow evening into early tomorrow night. A
narrow band of 6-12 inches could occur as a result. Due to position
uncertainty, we spread this enhancement in precipitation out over a
slightly wider location than will likely occur in reality. Our
current forecast hedges the placement slightly more toward the
eastern solution (Washington County to Loudoun County), but has an
enhancement over that broader region. This is also why the Winter
Storm Warning extends southward in Fauquier Co. and wraps around the
DC Metro area.

The immediate DC Metro will likely fall within a relative min
between these two areas of precipitation enhancement, but will still
experience several hours of accumulating snow this evening into
tonight. Another localized minimum will be between the inverted
trough and the Allegheny Front where downslope flow could diminish
accumulations especially in eastern Mineral and eastern Grant
counties. Very little in the way of snow may end up falling in the
shadow of the mountains just to the east of the Allegheny Front and
also in the Central Shenandoah Valley.

Snow totals will be heavily elevation and snow rate dependent. With
such marginal temperatures in place, a lot of the snow will be lost
to melting at lower elevations with surface temperatures above
freezing, while higher elevations have lower temperatures and
accumulate more efficiently.

Snowfall: 2-4 inches is expected in the DC Metro, although there
could be locally lower totals at the lowest elevations if warmer
temperatures and lighter precipitation rates verify. 4-7 inches is
expected along the Bay shore from St. Mary`s northward through
Baltimore City, with higher totals of 6-12" from Carroll eastward
toward Cecil. Higher totals of 8-16 inches are expected in the
Catoctins, where snow will accumulate more efficiently throughout
the event. Snow will also accumulate efficiently southward along the
Blue Ridge, where a general 6-12 inches of snow is expected. To the
west of the Blue Ridge, snow totals will be heavily elevation
dependent, with 3-6 inches expected at higher elevations between the
Allegheny Front and Blue Ridge, while lower elevations in the
Central Shenandoah Valley and Potomac Highlands see little in the
way of accumulation. A general 1-3 inches is expected at lower
elevations along the I-70 corridor to the west of the Blue Ridge,
with the exception of near Hagerstown, where they could receive
significantly more snow under the inverted trough. For now, that
inverted trough area which extends southward from near Hagerstown
into Frederick and Loudoun is forecast to receive around 3-6", but
as mentioned before, the gradient will likely be tighter than
depicted, and the max there will likely be between 6 and 12 inches.
In the Alleghenies Winter Storm Warnings are in effect. Snow will
linger much longer there throughout Monday within upslope flow
behind the departing low. Snowfall accumulations there are expected
to reach 6-12 inches by Monday evening. Elsewhere, snow should wind
down by mid-morning Monday.

[mitchnick]

1 minute ago, Ji said:

Stop cherry picking negative things just to incite the board

That’s something a bored troll would do. Really fv3??

Lol. You just can't stop can you? What is wrong with you?

The 2 major metro areas, Baltimore and DC, went from 12.9" to 8.3" and 9.1" to 6.7" respectively. That's not cherry picking.

[MDstorm]

Regarding the above NAM snow maps (Mitch vs Ji), one is Kuchera and the other is 10:1

[Weather Will]

WB 6Z 3K NAM gives more moisture to western burbs than 0Z.

[Weather Will]

WB 3K 6Z NAM zoomed snow map comparison to 0Z.

[Weather Will]

We will know if WB 3K NAM is correct soon.  10 am radar compared to 0Z. 10 am surface temps are colder too do to rates.

[Ji]

We will know if WB 3K NAM is correct soon.  10 am radar compared to 0Z. 10 am surface temps are colder too do to rates.

Hopefully This won’t be the one time the Nam 3k fails on thermals