December 9th Storm - Snow Map

track17 wrote:Flurries in Toms River skins looks like you were right as usual thanks again

Now lets get it to come down good. I think this afternoon it gets cranking I hope.

Flakes have started here in Westchester

skinsfan1177 wrote:

rb924119 wrote:

skinsfan1177 wrote:The issue I see is that it may not stick to roads right away more like grassy areas. We shall see any snow is good snow and this is a great start to the year. I would also like to know and understand snow growth. Because that seems to be a issue with this storm. Any one that has knowledge on it fire away

Not sure that's what I'm asking I have heard that snow growth isn't great with this storm it has to do with reading the soundings and stuff way beyond my knowledge. Not that we are getting less than is predicted but we could of done better

Snow growth is dependent upon two things: how much forcing for ascent is there (I.E. how strong is the vertical motion and it's ability to produce precipitation?), and what's the thermal profile within the zone of strongest forcing for vertical ascent? Where the strongest vertical motion overlaps the most ideal part of the thermal profile will determine the degree of snow growth. I can't go into any more detail than that right now, skins, but I can do a more detailed write-up later about this to better explain. It gets tricky too, because crystal formation habits play a role, and this is where you hear things about the dendritic growth zone. If that is maximized, then you're in great shape for a good snow event.

Thanks rb awesome I look forward to it. Also if you can is it true that snow growth for this storm is bad and how do read soundings to know thanks

To be honest, I cannot answer this. I haven't been following this system that closely; I didn't even make a forecast, aside from the outlook from a couple weeks ago. That's the only reason I e been following this period. If I had made an actual event forecast for this, I'd be able to tell you. Sorry, buddy :/ but maybe one of the others can chime in and come to our aid haha

Looking like I probably wont even see a coating now...

A very light fine snow just started. Union County, NJ. 34 degrees

mikeypizano wrote:Looking like I probably wont even see a coating now...

Where you getting that info

NWS is saying accumulating snow will not start until late morning or early afternoon Has not changed anything Still calling for 5-7 in New York area

The issue is people where expecting it to start overnight but that was not the case I always though it was a late morning event with steadier snow in afternoon. But people calling a bust this early is not correct. PATIENCE

Radar filling in nicely

Mt Holly Update:

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
630 am update: The dry air near the surface continues to be a
hindrance for snow making the move northward, but it looks like
the process is beginning now thanks to substantial large-scale
lift approaching the area. As a potent vort max approaches the
Mid-Atlantic today, jet dynamics combined with considerable
differential cyclonic vorticity advection will permit widespread
precipitation to develop north into the area. Timing of the vort
max appears to have slowed by 3-6 hours...another reason for the
slower onset of precipitation across the area. However, the dry
air near the surface will continue to pose problems early on in
the event for much if any snow to accumulate north of the
Mason-Dixon Line. The trend of the HRRR and HRRR-X has been
downward with QPF today, though not substantially so. The 06Z NAM
Nest continues rather bullish in comparison but has shifted the
snow banding somewhat eastward. The dry look of the GFS is
worrisome, particularly with considerable precipitation ongoing
in the western Atlantic (which may prevent as much northward
advection of more substantial moisture).

Using an updated consensus blend of the 06Z GFS, 06Z NAM Nest,
several HRRR cycles, the 00Z RGEM/WRF-ARW/WRF-NMM, the latest
WPC guidance, and some continuity, QPF went down a few
hundredths of an inch across the area, with most places
receiving up to an inch less of snow than the forecasts this
past evening. This warrants no change to any of the winter
headlines at this point, though the winter storm warning for the
counties bordering the Delaware River looks pretty borderline.

General thinking is aligned fairly similarly to the previous
forecast, with the ramp-up in snow during the next 6 hours and
the best period of accumulation for the CWA this afternoon (into
early this evening). Did slow the increase of PoPs north of the
Mason-Dixon Line a little bit more, but based on latest radar
trends, expecting to see some flakes in the urban corridor
within the next couple hours.

Given the rapidly evolving nature of the forecast given some
short-fused model uncertainty/discrepancies, expect frequent
updates/amendments to the forecast today. Sometimes, higher-
confidence forecasts can deteriorate as the event nears, and
this appears to be a classic case of that.

MattyICE wrote:Start time was never supposed to be before daybreak. With a cold, dry airmass and some lower dew points any lead precipitation was going to be virga and not reach the ground, rather try to moisten the atmosphere.  Also, the lead low was always supposed to sort of slide a bit S and E. The last 6, 8? Runs of the NAM have shown the real low coming a bit later and almost looking like the precip wouldn’t make it back W...and then it blossoms. I think if the radar isn’t filling in with actual snow reaching the ground by say 10am then maybe were in a slight amount of trouble. I also think this is something better forecasters (like here) considered when they went with a high end of 3-6 rather that 6-8/10 like some guidance showed and many Mets followed. Just my 2 cents. Think most are still in line for a widespread 3+ event.

Great analysis Matty.  Couldn't agree more.  Looking at satellite and current conditions I still think Franks Map is pretty much right on target.  

Here is the current 500mb map.  You can see by the small black arrows that the N energy is just now interacting with the Southern trough.  Its this interaction that will lead to the southern longwave trough to tilt from positive towards neutral.  Its this tilt and the timing of when and where that will be key in getting the precip shield to expand N&W as we go throughout the day.  As they cont to interact we should see heights rise along the east coast.



As seen by the current radar loops that is already stating to happen. A lot of what you see on this radar is virga however, like Matty said the mid and lower levels of the atmosphere have to saturate still throughout most of our coverage area. Current observations still show a large gap between dew points and surface temps.






I have to say the S energy does look to be slightly faster or out ahead of the N energy relative to what models predicted it would be.  I'm not sure just yet is this will be a problem or not.   An interaction and a positively tilted trough that tilts neutral a few hourse later than anticipated could allow the heaviest banding to slide a smidge further east than forecasted leading to shaving 1-2" off the top of the totals.  For now I'm not that concerned, but as we head into the early to midafternoon we should see if we are going to bust high/low or baby bear...just right.



The 300mb jet is still looking to be in great position for when the 500mb trough tilts this 300mb jet configuration will enhance lift over most if not all of our area.  That is a strong jet!

Steadier flurry now in Bayville, with thicker flakes. 36 degrees, but looks like we are heading in the right direction and the show is gonna start sooner than later.

skinsfan1177 wrote:

mikeypizano wrote:Looking like I probably wont even see a coating now...

Where you getting that info

skinsfan1177 wrote:The issue is people where expecting it to start overnight but that was not the case I always though it was a late morning event with steadier snow in afternoon. But people calling a bust this early is not correct. PATIENCE

There is a little snow over me, but air is too dry, so nothing is falling. I almost always get screwed in costals, I am too far inland...

Sanchize06 wrote:Mt Holly Update:

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
630 am update: The dry air near the surface continues to be a
hindrance for snow making the move northward, but it looks like
the process is beginning now thanks to substantial large-scale
lift approaching the area. As a potent vort max approaches the
Mid-Atlantic today, jet dynamics combined with considerable
differential cyclonic vorticity advection will permit widespread
precipitation to develop north into the area. Timing of the vort
max appears to have slowed by 3-6 hours...another reason for the
slower onset of precipitation across the area. However, the dry
air near the surface will continue to pose problems early on in
the event for much if any snow to accumulate north of the
Mason-Dixon Line. The trend of the HRRR and HRRR-X has been
downward with QPF today, though not substantially so. The 06Z NAM
Nest continues rather bullish in comparison but has shifted the
snow banding somewhat eastward. The dry look of the GFS is
worrisome, particularly with considerable precipitation ongoing
in the western Atlantic (which may prevent as much northward
advection of more substantial moisture).

Using an updated consensus blend of the 06Z GFS, 06Z NAM Nest,
several HRRR cycles, the 00Z RGEM/WRF-ARW/WRF-NMM, the latest
WPC guidance, and some continuity, QPF went down a few
hundredths of an inch across the area, with most places
receiving up to an inch less of snow than the forecasts this
past evening. This warrants no change to any of the winter
headlines at this point, though the winter storm warning for the
counties bordering the Delaware River looks pretty borderline.

General thinking is aligned fairly similarly to the previous
forecast, with the ramp-up in snow during the next 6 hours and
the best period of accumulation for the CWA this afternoon (into
early this evening). Did slow the increase of PoPs north of the
Mason-Dixon Line a little bit more, but based on latest radar
trends, expecting to see some flakes in the urban corridor
within the next couple hours.

Given the rapidly evolving nature of the forecast given some
short-fused model uncertainty/discrepancies, expect frequent
updates/amendments to the forecast today. Sometimes, higher-
confidence forecasts can deteriorate as the event nears, and
this appears to be a classic case of that.

Nice. And to mirror Mt Holly this is Upton:

Main update is to slow down steady snow development until late
morning into early afternoon. Deformation axis of snow extending
from GA/AL up towards DC area this morning is expected to
expand northeastward during this time ahead of amplifying
longwave trough and approaching southern stream energy. Will
have to evaluate through the day whether the slower onset will
reduce snowfall amounts slightly, although the snowfall taper
is slower than 12hrs ago as well.

Otherwise...water vapor imagery showing strong shortwave energy
diving down the backside of Great Lakes trough early this
morning, helping to amplify the longwave trough and lift
intense southern stream shortwave up the coast today. Quite a
bit of convection developing through Florida and off the SE and
Mid Atlantic US coast in subtropical moisture feed ahead of
these dynamic features, meanwhile while a broad deformation
snow band exists from AL/GA up through the Central appalachians.
Shortwave energy will continue to race up the coast today, with
at least the eastern 1/2 to 2/3rd of CWA under a favorable
right rear of 170-180 kt jet dynamics. At the surface, low
pressure tracks from the Carolina Coast early this morning to
near the 40/70 lat/lon benchmark by this evening.

Snow will increase in coverage/intensity late morning into
early afternoon as large scale lift increases and a bit of the
offshore sub- tropical moisture feed advects towards the coast.
Thermal profiles would support snow across almost all the areas,
outside of some initial mixing with rain at onset for city/LI.

W/W/A`s issued yesterday are still in effect, with only slight
changes to snowfall. Models are still indicating some weak mid-
level frontogenesis and negative epv aloft across LI/CT this
afternoon/evening which signals potential for some moderate
snow banding. This presents a low to moderate probability of
1/2 to 1 inch per hour snow fall rates in the afternoon and
evening in vicinity of the warning area. 00z models trended
farther west with qpf axis, which has increased the likelihood
for 3 to 6 inches of snow across much of the advisory area, and
2 to 4 inches of snow into Orange County, where advisory has
been expanded into.

In terms of ptype, thermal profiles are cold enough for most of
the region to be in the form of snow. But an 850-950 hpa warm
layer still appears that it could make inroads into far se
portions of the area late this aft/eve to result in a mixing
with or changeover to rain as low pressure make the closest
approach. The reason for this is that northern/southern stream
phasing of energies does not start taking place until late
today/this evening as the low/mid level low is tracking SE of
LI, which does not allow for enough tightening of the thermal
gradient to ensure cold air all the way to the coast through the
event. Based on an ensemble of thermal profiles, the south fork
of LI has the highest probability a period of mixing with rain
and sleet this afternoon into evening, possibly working
northwest into the north fork of LI and SE New London County in
the evening.

In terms of QPF, models have wavered a bit from run to run and
between each other with QPF but generally still depicting a
range of 1/2 to 3/4 of an inch of liquid equivalent across LI/CT
(highest east), 4 to 6 tenths across NYC/NJ metro and SW CT/SE
NY border, tapering to 1/4 to 4 tenths of an inch for Orange
county. With boundary layer and surface temps holding around
freezing along the coast during the event, and upper 20s to
lower 30s across interior, snow ratios not expected to be too
much above 7-10 inches of snow to 1 inch of liquid.

In terms of snowfall, based on P-type and dynamics mentioned above,
still expecting 5 to 7 inches of snow for SE CT and Eastern LI
(except for far SE portions due to mixing). Farther west a
solid advisory level snow expected, with 3 to 6 inches to around
the NY/NJ metro and the Hudson River. NOTE: Based on the slower
onset of steadier snow, marginal surface temps, and diurnal
solar insolation, expecting roadway snow accumulation to become
more of a concern and hazard starting in the mid to late
afternoon through the evening.

In term of uncertainty, besides the p-type issues for se areas,
the offshore convection could be playing a factor in affecting
magnitude of offshore moisture feed into the region. Based on
variability from run to run between models and current model
spread, snow amount could have to be increased or decreased by 1
to 2 inches from current forecast in spots. Will have to
monitor mesoscale models, satellite and radar trend today.

Once again, along with the slower snow onset, accumulating snow
appears to be slightly slower to taper off than what appeared
12 hrs ago; not until the longwave trough axis begins moving
into the region tonight. Accumulating snow expected to taper
off across the NYC metro by around midnight, and late night
across Eastern LI/SE CT.

Flakes starting here on the island

There is a dry wedge of air at MTTY Ice and doc have pointed out, once this gets saturated then we will be in business. At the car shop, water pump went hope to be out of here by noon yiks!!

Here is the NE radar, look at that fetch of moisture beautiful

Radar now shows blue above the Jersey Shore, but no snow coming down...hopefully the air is saturating and getting ready for a 10 am blast off. Radar looks great for the whole afternoon/evening for pretty much all of the 95 corridor and east.

First flakes started at around 9am. Current temp is 37*

Radar really starting to fill in

docstox12 wrote:OK Doc, encouraging report.Radar looking better and better.In good shape here in the LHV with temps.

Good for you HV peeps Doc. I always judge asnowstorm asmeaningful or not on whether or not the grass is completely covered and do the roads get snow covered. Looks like ayes to both even all the way up by you now. Nothing better to put one I. The holiday spirit.

Also I’m not at all a football” guy, but watching the cadets march in the snow today and seeing the beauty of our military on display at Army Navy game IN THE SNOW will be phenomenal. The flyover and the orderly way thousands of our best young kids march in and play in a respectful manner will be awesome. The snow will add to it.

Snowing at a good clip here in Manorville, skies actually got very dark. Encouraging signs!

Very very light snow has just started about a half hour ago. Does anyone know when we will the heaviest snow will start I just want to do a few errands and finish up my Christmas shopping

Flurries coming down in Brooklyn