Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

fxus61 kbgm 120343 
afdbgm

Area forecast discussion
National Weather Service Binghamton New York
1043 PM EST Mon Nov 11 2019

Synopsis...
light snow is ongoing around The Finger lakes through the
western Mohawk Valley this afternoon, with a strengthening low
pressure system moving in tonight and causing rain and mixed
precip, and finally snow, to spread across the rest of the area.
This may lead to a messy commute Tuesday morning. Snow will be
heavy at times in the northern Finger Lakes east from Syracuse
to Utica. Near record cold is expected midweek with lake effect
snow showers.

&&

Near term /through Tuesday/...
1040 PM update...cut back snowfall accumulations for the 0z to
06z time range as dry slot has really dominated the period thus
far. Will leave headlines as is for now, as temperatures will be
falling rapidly into the low 20s and possibly teens across the
north, and even if snow amounts don't quite reach warning
criteria, it will still be a very slick commute Tuesday morning.



815 PM update...extended the freezing rain line further north
into Onondaga County as several reports have been coming in with
freezing rain and a light Glace forming on flat surfaces. Cold
air will quickly overtake the column over the next couple of
hours and when heavy precipitation moves in, it will likely fall
as all snow. Further south, expecting only a brief period of
wintry mix before the cold air quickly takes over and turns it
over to all snow during the early morning hours on Tuesday.

5 PM update...made some minor changes to forecast, as
temperatures have trended a little colder across the lake plain,
central New York and southern tier while they have been trending a
bit warmer than forecast across NE PA.

The slight decrease in forecast temperatures does produce a
wider area of light icing than previously forecast, but no
significant changes in overall snowfall amounts, other than a
few tenths of an inch here and there. Will watch and see how
temperatures evolve over the next couple of hours and make
anymore necessary changes at a later time.

330 PM update...

Deepening surface low remains situated over the Ohio River valley
this afternoon, with a strong baroclinic zone extending northeast of
this feature through PA and into eastern New York and New England. A weak
wave passing through upstate New York has touched off some light snow and
snow showers with a decent amount of moisture in the area ahead of
the main system. Snow has been contained so far across our far
western zones, from the western Mohawk Valley, through Syracuse and
the northwest portions of The Finger lakes region. A few sprinkles and
light rain showers are possible to the south and east in the warmer
air across the rest of central New York this afternoon.

Light snow will continue across those areas the rest of the
afternoon, not budging much as the aforementioned surface low begins
to pivot into PA, then finally through eastern New York and into New
England tonight. This will create a strengthening area of
frontogenesis across our western zones after 7pm, with steadier
precipitation migrating eastward through the night with the passing
front.

This is where the forecast becomes a bit more complicated. Models
soundings continue to indicate a dry slot just ahead of the front
across most of central NY, which would reduce the amount of ice
present across those areas even as surface temperatures begin to
fall below freezing. This results in a risk for more of a sleet and
freezing rain mix before a transition over to snow behind the front.
Meanwhile, in the areas of ongoing snow across our far western
zones, model soundings show a very shallow layer of warm air aloft
developing briefly after 0z from around Utica to Syracuse to Penn
Yan. This could result in a brief period of mixed precipitation -
likely snow/sleet along and west of this line, but some freezing
rain cannot be ruled out. Otherwise, more steady rain will hold on
for longer across NE PA, the Catskills, and the Poconos ahead of the
front. Soundings again indicate a brief period of mixed
precipitation - though mainly snow/sleet - then a final transition
over to snow before sunrise Tuesday.

Snow rates will also ratchet up along the frontal boundary. Healthy
frontogenesis will provide the forcing necessary for a quick burst
of heavier precipitation as the feature passes through. Soundings
across our far western zones are indicating a generally saturated
profile through the snow growth region, and apart from the
aforementioned brief appearance of the warm layer aloft,
temperatures stay cool throughout the profile. Soundings saturate
and cool as the front tracks eastward. This will result in heavier
snow rates along the front, with our highest snow totals up to 6-10
inches from the western Mohawk Valley to The Finger lakes and
western Steuben County, given the long duration of snow there.
Eastward to a line from around Bridgewater to Marathon to Elmira,
snow totals up to 3-6 inches will be possible. Totals taper off
eastward across the rest of our forecast area, finally dropping to
below an inch across the western Catskills and Poconos. Otherwise,
there will be a risk for a glaze of ice across those areas where
freezing rain can occur. Even where mostly rain can occur, there
temperatures quickly fall back overnight with a risk for wet
roadways to turn slick.

Snow associated with the exiting system pulls out of our eastern
zones later Tuesday morning - but then a shift to strong northwest flow
will allow for lake effect snow bands to develop, continuing through
Tuesday afternoon and evening. A well-mixed boundary layer will help
stronger winds aloft mix down to the surface, with gusts up to 30mph
not out of the question. Temperatures bottoming out in the teens and
20s early Tuesday peak in only the 20s to low 30s Tuesday
afternoon.

&&

Short term /Tuesday night through Wednesday night/...
304 PM update...
main concerns in the short term remain focused on the onset of
very cold air and a short period of accumulating lake effect
snow showers southeast of Lake Ontario into Onondaga, sern
Cayuga, Madison, Cortland and Chenango counties. Quiet and
warmer weather is expected Wednesday into Wednesday night.

Behind the departing low pressure system a brief but potent
lobe of very cold will swing through the region Tuesday evening-
night. A nearly co-located upper wave will rotate across New York at
the same time and support the development of lake effect snow
showers into central New York. 850mb temperatures will drop to around
-17c within this air mass, with mixed layer heights deepening to
just under 10k ft. There should be enough moisture wrapping
around the system, combined with these positive lake effect
features to produce several inches of snow southeast of Lake
Ontario...inland to around Cortland and Chenango counties.

There are some variables going against significant accumulation
as well. The window of opportunity for accumulating snow is
fairly narrow...roughly around sunset Tuesday to just before
sunrise Wed morning. The wind flow will be slightly variable as
well...which will move the lake band around enough to spread the
snow accumulations around. There is also some shear in the top
part of the mixed layer...which may allow for enough disruption
to the convection to keep it fairly disorganized.

Heights rise aloft rapidly during the day Wednesday which will
back the winds and shift the weakening lake band north and
eventually out of the area by the afternoon. A surface high
builds across the region late Wed into the evening and Ushers in
a southerly flow on the back side of the ridge, which will
allow a weak warm air advection regime to develop and increase cloud cover
slowly through Wednesday night.

Temperatures Wednesday morning will be some of the coldest so
far this season with lows bottoming out in the lower teens and
single digits above zero. As the cold air pours in through the
day, temperatures will not warm too much...only into the lower
20s north and upper 20s south. A steady northwest wind will keep wind
chills in the single digits. Another cold night is expected
Wednesday night...especially over the ern zones where less cloud
cover may lead to rapid radiational cooling into the single
digits and teens above zero. Might be a few deg warmer to the
west as the clouds blanket the region.

Snow associated with the exiting system pulls out of our eastern
zones later Tuesday morning - but then a shift to strong northwest flow
will allow for lake effect snow bands to develop, continuing through
Tuesday afternoon and evening. A well-mixed boundary layer will help
stronger winds aloft mix down to the surface, with gusts up to 30mph
not out of the question. Temperatures bottoming out in the teens and
20s early Tuesday peak in only the 20s to low 30s Tuesday
afternoon.

&&

Long term /Thursday through Monday/...
304 PM update...
cloud cover will persist across much of the region Thursday and
thur night as a weak wave passes by to the north. Temperatures
will be slightly milder on Thursday with highs in the 30s. Lows
thur night will drop into the lower to mid 20s. A brief bump up
in the temperatures on Friday...into the upper 30s and 40s will
be replaced by another blast of Canadian air later Friday into
early Saturday. Along with a shot of snow showers across the
north...temperatures will drop back into the teens and 20s early
this weekend. However, this cold snap will be short-lived with
highs on Sunday back into the lower to mid 40s...under quiet
weather conditions.

&&

Aviation /04z Tuesday through Saturday/...
a winter storm will be pushing through the region overnight with
IFR conditions likely for everywhere except maybe avp. There is
a chance of sleet and freezing rain as well tonight before the
push of colder air arrives from the northwest.

Kavp stays south of the frontal boundary and associated
precipitation/restrictions until early Tuesday morning.
However, rain to wintry mix is then expected towards dawn with
development of possible fuel alternate to IFR conditions.

Winds will be relatively light overnight, but will pick up
behind the front tomorrow, gusting to 15-20 kt after 14z from
the northwest.

Outlook...

Tuesday night through Wednesday...northwest winds and scattered
lake effect snow showers/intermittent restrictions; especially
ksyr but occasionally kbgm-kith-krme.

Wednesday night through Saturday...mainly VFR.

&&

Bgm watches/warnings/advisories...
PA...Winter Weather Advisory until 9 am EST Tuesday for paz038-039.
New York...Winter Weather Advisory until 9 am EST Tuesday for nyz022>025-
044>046-055-056.
Winter Storm Warning until 9 am EST Tuesday for nyz009-015>018-
036-037.

&&

$$

National Weather Service Glossary of Abbreviations