Jump to content
  • Member Statistics

    17,608
    Total Members
    7,904
    Most Online
    Vesuvius
    Newest Member
    Vesuvius
    Joined

Upstate/Eastern New York


 Share

Recommended Posts

The jet coupling on the 18Z NAM looks like a hot spot for upstate NY. All the way from KROC to Watertown. Ridiculous omega values on the sounding basically perfectly co-located the the DGZ (shallow but still a good sounding). This looks like fat dendrites are gonna be falling during an awful commute Friday morning and then some...
All this thanks to being right between the left exit region of the trough and right entrance of the jet to the north. This, coupled with a juiced deformation band with ton of stretching and frontogenesis..sounds like it'll be ripping. 

 

image.png.8e6d7046bc9d9ef3ef2941a775d07212.png

 

 

2020020518_NAM_045_42.97,-77.56_winter_ml.png

  • Like 2
  • Thanks 2
Link to comment
Share on other sites

4 minutes ago, Paulie21 said:

The jet coupling on the 18Z NAM looks like a hot spot for upstate NY. All the way from KROC to Watertown. Ridiculous omega values on the sounding basically perfectly co-located the the DGZ (shallow but still a good sounding). This looks like fat dendrites are gonna be falling during an awful commute Friday morning and then some...
All this thanks to being right between the left exit region of the trough and right entrance of the jet to the north. This, coupled with a juiced deformation band with ton of stretching and frontogenesis..sounds like it'll be ripping. 

 

image.png.8e6d7046bc9d9ef3ef2941a775d07212.png

 

 

2020020518_NAM_045_42.97,-77.56_winter_ml.png

THANKS PAUL. you do not post often but it is always very informative. Soundings is my next goal. I have trouble figuring them out and reading those values. Are you looking at 700mb or 850mb fronto to assess best banding potential?

  • Thanks 1
Link to comment
Share on other sites

Kbuf for overnight through tomorrow..

Precip first in the form of snow then changing to a wintry mix tied
to the jet and warm air advection aloft quickly spreads to the
northern Ohio valley and lower Great Lakes late this evening. Trend
that showed up yesterday with quicker arrival of widespread precip
continues, with main warm air advection driven precip sweeping
across region from the southwest by daybreak on Thursday. Ptype with
this initial wave of precip will mainly be snow though a mix will
develop on the southern end of it as warm layer aloft (H85-H8)
surges into western NY. Ptype will change to mix of fzra, sleet and
snow over the Southern Tier to the Finger Lakes by 12z, but then as
the warm layer aloft slides more east than north, the warm layer
aloft and potential for mixed precip will struggle through Buffalo
and Rochester by late morning and feasibly may not reach the
northern reaches of the Niagara Frontier and the North Country at
all.

Though steadier precip will lift through by mid morning, there will
be intervals of additional steadier precip through the rest of the
day as region remains within right entrance region of 180+ kt jet
and along or just northwest of tight baroclinic zone. Sfc low and
sfc warm front all the while will remain south of our area, though
there could be increased low-level convergence from inverted trough
extending north from the sfc low. Certainly could see precip taper
with the occasional strip out of deeper moisture/DGZ. For now just
focused the ptype based on the warm layer aloft. Seems the greatest
chance of snow to freezing drizzle/drizzle would be over northern
portions of the Niagara Frontier.

Overall in terms of snow and ice amounts, this forecast did not
change much from previous one. However, there is now some higher
snow totals from late tonight through Thursday afternoon from
Niagara county to the Rochester area as that part of the region may
stay right around zero aloft as the ECMWF was showing ydy and now
the NAM and Canadian indicate. GFS which remains a warm outlier has
come down slightly with its warm layer aloft. Only change to
headlines for this first portion of this double barelled event was
to extend the winter weather advisory til 23z for the areas from
Buffalo to Rochester, but otherwise the headlines were left intact.
Morning commute on Thursday will be impacted by the wintry mix and
its possible the evening commute over parts of northern Niagara
Frontier could be impacted especially as the wintry mix begins to
change back to snow.
Link to comment
Share on other sites

Part 2

Thursday night an upper level trough will swing across the
Central Great Lakes, with a strong surface high pressure over
western Ontario Canada providing cold, northerly flow across
much of our region. A surface low will be deepening as it
advances northeastward up the spine of the Appalachians Thursday
night, this also along a tight baroclinic boundary below 700
hPa.

To start Thursday night, surface temperatures will remain around
freezing across the interior Southern Tier and through the Finger
Lakes, and perhaps to the southern Tug Hill region...with a still
elevated warm layer aloft. This scenario will continue the threat of
mixed precipitation (sleet and freezing rain) until deeper colder
air from the northwest seeps southeastward. This colder air will
transition precipitation across the entire region to snow by around
midnight.

Later Thursday night a 850 - 700 hPa frontogentic boundary will form
to the northwest of the surface low. This boundary will serve as a
focus for higher snowfall, that will also be enhanced Friday as a
closed 700 hPa low develops over WNY. Synoptic snows Thursday night
will become greater towards the east as this frontogenetic forcing
increases...with snowfall rates of an inch per hour likely under
this band of snow.

As the synoptic snows pull out eastward Friday, a colder airmass
aloft will support lake effect snow under a northerly flow. Bufkit
soundings display a decent amount of moisture within the snow
dendritic growth zone, and inversion heights rising Friday towards 6
to 8K feet. Snow ratios will rapidly increase within this colder
airmass and additional lake effect snow will fall. Will maintain the
watch as is, with potential for a half a foot of snow...with upwards
towards a foot of snow possible along the southern shoreline of Lake
Ontario, and also the Chautauqua Ridge. To the east where a stronger
frontogentic forcing will be found again here upwards to a foot of
snow will be possible. Lowest amounts will be around Metro Buffalo
and towards Niagara Falls where synoptic snows will be lower under
less forcing aloft and also not within a favorable location for lake
effect snow under a north to northwest flow.

Surface high pressure will then build towards our region Friday and
Friday night, with this feature and its drier air weakening the lake
snows and providing clearing to the North Country. With 850 hPa
temperatures dropping well into the negative teens, temperatures
Friday night over a fresh snowpack will lower into the lower teens
across the Lake Plain, and single digits inland. Across the North
Country where skies have the greatest probability of
clearing...overnight lows could drop well into the negative single
digits.
Link to comment
Share on other sites

7 minutes ago, PaulyFromPlattsburgh said:

THANKS PAUL. you do not post often but it is always very informative. Soundings is my next goal. I have trouble figuring them out and reading those values. Are you looking at 700mb or 850mb fronto to assess best banding potential?

Thank you.

Just glancing at the sounding, the blue box on the left I circled implies strength of upward vertical velocities. This is a rather strong signature and almost a textbook case because it is essentially in the same layer as the DGZ. DGZ is the dendritic growth zone, an thermal area between -12 to -18 C (highlights on the skew-T here with red dashed lines I made). Soundings highlight any saturated (has to be saturated) column with yellow on the temperatures line. The DGZ will help produce larger flakes and the lift will help flakes stay in that layer and make larger aggregates as they eventually fall. 

The reason for this strong signatures of upward vertical velocities is due to jet coupling enhancing lift (left exit region of trough and right entrance region of jet to the north), as well as frontogenesis aloft. 850mb is somewhat weak in this scenario. Looks better ~700mb. 

image.png.4d9ddddb5d62819069baa938b26b35b5.png
 

  • Thanks 1
Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share

  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...