Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Buffalo New York
441 am EDT Tuesday Mar 11 2014
mainly cloudy skies will be in place today with another day of mild
temperatures. Tonight...a developing winter storm system will shift
from the Central Plains to the Ohio Valley. Precipitation will start
as light rain then change to a wintery mix before changing to all
snow except across the southern tier where light rain will hang on
longer. Wednesday and Wednesday night the storm will pass just south
of New York state with moderate to heavy snow and blowing snow
creating hazardous travel across our area. The storm system departs
on Thursday with snow ending and a sharp dip in temperatures.
Near term /through tonight/...
an area of low pressure is found over central Quebec this morning
with a weak/dry cold front extending south across Lake Ontario and
western New York to south of Lake Erie. A breezy southwest flow is
found ahead of the cold front with lighter westerly winds behind the
front. Mild temperatures remain along with continued warm air
advection across western and central New York. The air behind the
front is not very cold so not expecting anything more than a wind
shift with the frontal passage. Temperatures are ranging in the middle 30s
across northern counties to middle 40s toward the southern tier. Expect
temperatures to remain nearly steady or slowly continue to rise this
morning. Area radars remain largely free of returns as moisture is
limited to the middle and upper levels. Laps sounding showing a wedge
of dry air from the surface to about 500mb. Some very light mist/fog
is being reported on surface observation as dewpoints now running above
freezing over some patches of lingering snow.
Through today...expect a dry and fair weather areawide as New
York state comes under the influence of a col between two high
pressure systems over the northern plains and western Atlantic...and
departing low pressure over Quebec and a developing winter storm
over the plains states. Skies will feature middle and high clouds
increasing from southwest to northeast through the day in advance of
the developing storm well to our southwest. Expect the leading edge
of the precipitation associated with the winter storm to remain to our
southwest across the Ohio Valley and Midwest states through the day.
Continued warm advection aloft will help high temperatures to run
above normal today reaching into the upper 40s and lower 50s. Expect
cooler temperatures along the Lake Shores and across the North County.
Focus tonight will remain on the approaching winter storm. Models
now show the storm center shifting from the Southern Plains into the
Ohio Valley through the overnight with a leading warm front bringing
a chance for light rain showers across much of upstate New York
early in the evening. Around or just after midnight the approaching
storm will swing the winds across New York around to the northeast
with increasing speed. This will advect cold air from the north
across our forecast area first at the surface then cooling aloft.
The warm layer aloft will bring some mixed precipitation issues for
a few hours overnight until the column cools. Mixed precipitation will
range from snow and sleet to sleet and rain north to south. BUFKIT
time-height profiles show a thin snow growth area about 15kft up
over a thick layer of warmer more moist air. Weak lift initially
along with mixed sleet and wet flakes will bring light accumulations
of about an inch across the Niagara Frontier ranging to plain rain
toward the PA border where warmer air will take longer to cool.
Little to no accumulation across the North County and Finger Lakes
until the storm center approaches closer Wednesday with rapidly
Short term /Wednesday through Thursday/...
..significant winter storm on the way for Wednesday...
To summarize...00z model guidance has continued a trend towards a
slightly farther north...deeper...and slower solution with the
midweek system. The net result of these changes will be more wintry
mix along the PA state line which will hold down snow accumulations
there...and even higher snow accumulations farther north from the
Niagara Frontier across the greater Rochester area to the Eastern
Lake Ontario region. Storm totals have been increased into the 12-16
inch range with a few spots possibly reaching 18 inches. The deeper
solution also leads to a further increase in forecast wind
speeds...with significant blowing and drifting snow developing
Wednesday afternoon and evening.
00z GFS/ECMWF/Gem are all in excellent agreement with the 00z NAM
deeper and farther north with the surface low. NCEP/wpc forecasters
recommend a solution closer to the GFS/European model (ecmwf) consensus...although
with the idea that this may be just slightly too far south.
A surface low will reach the lower Ohio Valley by Wednesday
morning...before crossing central PA during the day and reaching NYC
by evening. This low will continue into the Gulf of Maine by
Thursday morning. Aloft...the Pacific vorticity maxima and the
northern stream trough will fully phase by the time the system
reaches our longitude...which is notably faster in phasing than
model guidance from several days ago and explains the deeper/farther
north trend seen in recent model runs. The phasing streams and ample
moisture will produce an incredibly dynamic system.
Frontogenesis and deformation in the 850-600mb layer will rapidly
increase across the entire region Wednesday morning as the middle level
trough phases and deepens...forcing strong downstream ageostrophic
flow adjustments. At the same time...strong upper level divergence
will develop within a coupled jet structure formed by the right
entrance region of a 150+ knot upper level jet over Quebec...and a
120+ knot upper level jet over the lower Ohio Valley. This will
combine to produce a period of deep layer ascent. A 12 hour period
of strong isentropic upglide will also be featured during the first
half of the event from late tonight through late Wednesday
afternoon. Moisture will be more than ample during this time
frame...with around 4 g/kg specific humidity near the 700mb layer.
Using these data...the Garcia method suggests around 8 inches of
accumulation in some areas just from the warm advection phase of the
During the afternoon and evening the surface low will be rapidly
deepening as it passes by to our south. As the system matures...
model guidance suggests the development of a well defined trowal
airstream and associated comma head to the northwest of the surface
low track. Within the trowal...strong deformation and frontogenesis
will continue to support strong convergence. This will continue to
produce moderate to heavy snow into the evening before slowly
tapering off from west to east overnight. The airmass will grow cold
enough for lake enhancement along the South Shore of Lake Ontario
during the afternoon and evening as lake induced equilibrium levels
rise to around 7k feet. This will likely add at least a few inches
to totals along the South Shore of Lake Ontario. Strong winds will
carry this enhancement well inland...probably as far south as about
the New York state thruway. Northerly flow will also result in upslope
enhancement during the afternoon and evening across the Chautauqua
ridge and other northward facing slopes in the southern tier and
Precipitation type will also be a concern through the first half of the
event across the southern tier. Early Wednesday morning it will
likely still be warm enough for just plain rain across much of the
western southern tier counties...with a narrow zone of wintry mix
transition across southern Erie/Wyoming/Livingston/Ontario counties.
This transition will sink slowly south during the morning...then
accelerate into PA during the afternoon with rain changing over to
snow. The changeover may go through a period of sleet and freezing
rain with minor ice amounts possible.
Storm total snow amounts of 12-16 inches are now expected in most
areas with some 18 inch amounts possible to the south of Lake
Ontario including the greater Rochester area where lake enhancement
will develop. If the current ptype forecast holds...amounts will be
considerably lower near the PA state line. Hourly snowfall rates may
reach or exceed 2 inches per hour locally in any mesoscale banding
that develops. Some thunder and lightning is not out of the question
with model guidance suggesting the potential for slantwise or even
upright convection. Some model point soundings show as much as
80j/kg of cape for parcels rooted in the 700mb layer.
North winds will become quite strong especially Wednesday afternoon
and evening producing significant blowing and drifting snow and near
blizzard conditions at times...especially within 20 miles of the
South Shore of Lake Ontario.
Temperatures will plummet through the 20s and into the teens during
the day Wednesday...then into the single numbers Wednesday night. A
few spots across the southern tier and east of Lake Ontario may drop
to a few degrees below zero by Thursday morning.
On Thursday any leftover wrap around/deformation snow east of Lake
Ontario in the morning will taper off. Lake effect snow showers will
still be likely south and southeast of Lake Ontario especially
during the first half of the day. This may add a few more inches in
some spots. Temperatures will be frigid by middle March standards...
with highs struggling to reach the middle teens across lower elevations
and possibly not getting out of the single numbers on the hills. It
will remain quite windy with blowing and drifting snow ongoing
especially in open areas.
Long term /Thursday night through Monday/...
colder air will follow the storm with northerly winds across Lake
Ontario producing a broad area of lake effect snow showers south of
the lake on Thursday. An extremely cold airmass for middle March will
dump into the trough in the wake of this system. Highs will struggle
to reach the middle teens across lower elevations...with lower teens
across higher terrain.
The cold will be short lived as the trough remains progressive and
quickly moves out of the area. Expect temperatures to recover to
near average again by Friday. The next chance of light snow will
arrive later Friday night and Saturday as a weaker middle level trough
digs into the Great Lakes and northeast. Highs on Friday and
Saturday will be in the middle to upper 30s or even lower 40s in the
High pressure ridging in across the Great Lakes will bring an end to
any chance of precipitation by Sunday. It will also turn colder however
with temperatures returning to below average.
Aviation /09z Tuesday through Saturday/...
mix of VFR ceilings with some patchy MVFR visible this morning. Expect
continued cloudy conditions through daybreak with middle and high level
moisture streaming across the region. Some southwest breezes also
found this morning ahead of a weak/dry cold front just to the west
of New York. Patchy mist/fog is causing the MVFR as dewpoints now
rising above freezing are overriding some patchy snowpack. On
Tuesday...any leftover MVFR ceilings across interior sections should
dissipate fairly early. Once these are gone...expect mainly overcast
VFR ceilings conditions for the balance of the daylight hours.
A developing winter storm system across the Central Plains this
morning will lift toward New York state this evening. Snow will
arrive after 04z across the Niagara Frontier with a mix of snow and
sleet toward the southern tier. This will bring IFR conditions.
Tuesday night...deterioration to MVFR/IFR with snow developing south
of Lake Ontario.
Wednesday...widespread IFR in snow...
Thursday...VFR/MVFR with scattered to numerous snow showers.
Saturday...VFR/MVFR with a chance of snow showers.
expect a modest southwesterly flow to continue across the lower
lakes region overnight...before weakening later today. A developing
winter storm will then bring northeasterly gale-force winds to Lake
Ontario on Wednesday and Wednesday night. A Gale Warning is now in
effect. Across Frozen Lake Erie a gale watch is in effect as
northeast winds may approach gale strength. The storm departs across
the Gulf of Maine to the Canadian Maritimes Thursday and Thursday
night with slackening northwesterly winds on the lower Great Lakes.
New York...Winter Storm Warning from 2 am Wednesday to 2 am EDT Thursday
Winter Storm Warning from 8 am Wednesday to 8 am EDT Thursday
Winter Storm Warning from 5 am Wednesday to 5 am EDT Thursday
Winter Storm Warning from 8 am Wednesday to 2 am EDT Thursday
Marine...gale watch from Wednesday morning through Wednesday evening
Gale Warning from 8 am Wednesday to 5 am EDT Thursday
Gale Warning from 8 am to 11 PM EDT Wednesday for loz042-