Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Buffalo New York
347 am EST Sat Mar 8 2014
a weak cold front will cross the region today with a few flurries or
light snow showers. A northwest flow of somewhat colder air tonight
will produce a few light lake effect snow showers southeast of Lake
Ontario with some very minor accumulation possible in a few spots.
Temperatures will cool to a little below average again over the
weekend before moderating early next week. Another push of colder
air will arrive by the middle of next week.
Near term /through tonight/...
satellite imagery showing middle level clouds increasing across the
region early this morning in advance of a weak cold front which was
analyzed from about Windsor to Ottawa at 08z. Radar imagery showing
some weak returns across northern New York...but this is not reaching the
ground as of yet with plenty of sub-cloud evaporation in the dry low
levels ahead of the front.
The weak cold front will push south across the region this
morning. Large scale support will remain displaced well northeast of
the region with a middle level shortwave and associated DPVA passing
through Quebec and into the Canadian Maritimes. This will leave only
low level convergence along the cold front as the primary forcing
mechanism...along with an added boost from Lake Ontario moisture and
upslope flow in the northwest flow regime behind the front.
Given the weak forcing and only limited moisture...expect nothing
more than scattered flurries and light snow showers in most areas.
The one exception may be across the western southern tier...where
the NAM/Gem/GFS all suggest a little greater snow chances and quantitative precipitation forecast
where moisture will be a little deeper in association with a weak
secondary middle level wave moving across Northern Ohio. With this in
mind have increased probability of precipitation to likely in this area with a coating to an
inch accumulation possible...especially across higher terrain.
Temperatures will make it into the middle 30s in many areas this
morning just ahead of the front. In fact...a few raindrops may mix
in at the start of any flurries or snow showers. This should quickly
change over to snow with evaporative cooling and the onset of low
level cold advection. Temperatures will likely pull back several
degrees this afternoon as cold advection increases...with
temperatures falling below the freezing mark in most areas by
Tonight cold advection will continue...with 850mb temperatures bottoming
out around -13c. This will be marginally cold enough to support some
lake response off Lake Ontario...with lake induced equilibrium
levels rising to around 5k feet. All of our locally run 6km
workstation WRF models develop some limited lake effect southeast of
Lake Ontario tonight...with some suggestion from the operational NAM
and Canadian Gem as well. The northwest flow will favor the greater
Rochester area initially later this evening...with flow slowly
backing late tonight and carrying lake effect a little farther east
into Wayne County and possibly northern Cayuga County. The flow has
enough northerly component to force a multiple band configuration...
which when combined with the weak instability will limit
Probability of precipitation have been increased to likely from Rochester to northern Cayuga
counties...with 1 to 2 inches possible tonight in persistent bands.
Outside of lake effect areas...flurries will slowly end across
western New York with skies clearing overnight. The north country will
clear out during the evening with no off lake trajectory. Expect
lows in the teens in most areas...with low to middle teens across
western New York and upper teens southeast of Lake Ontario beneath lake
effect clouds. The north country will be colder with its earlier
clearing...with lows in the single digits.
Short term /Sunday through Monday night/...
surface ridging is forecast to shift over New York state and the
lower Great Lakes region on Sunday. This will allow the majority of
the forecast area to see a good deal of sunshine through much of the
day except southeast of Lake Ontario where some lake effect clouds
and snow showers will linger through the morning. The surface high
will back the winds from northwest to southwest through the day and
lift the weak lake effect toward the southern Tug Hill region all
while subsidence squashes out the snow showers by the early
afternoon. Temperatures will run a little cooler than what is
expected on Saturday. Highs look to be capped in the upper 20s to
around 30 except across the Tug Hill with low to middle 20s.
Through the next 24 hours the middle and upper level pattern will
feature a progressive west-northwest to east-southeast zonal flow
across the northern half of the County including the Great Lakes.
Embedded within this will be a few subtle shortwaves and jet maxima
which will provide synoptic lift for some chances of showers.
Southwest surface winds will also advect increasingly warmer air
northward helping temperatures to climb into the lower 30s Sunday night
then toward the lower 40s on Monday.
An initial middle level shortwave Sunday night looks to bring chances of
snow showers overnight. More likely probability of precipitation are focused east of Lake
Ontario where additional upsloping on the tug may allow a few inches
of snow to accumulate. On Monday a second shortwave and compact area
of low pressure looks to cross the Great Lakes bringing another
chance of showers. Snow showers early will mix with then change to
rain showers as a warm front lifts north just ahead of the low
pressure system and surface temperatures climb toward 40 degrees across
western New York. This changeover may not occur east of Lake Ontario
where cooler temperatures will be found. The systems cold front is forecast
to cross Monday night with temperatures falling through the 30s and
chances of rain showers changing back to snow showers.
Long term /Tuesday through Friday/...
an amplifying ridge in the far west and a deepening midcontinental
trough will result in a much more unsettled weather pattern over the
lower 48. This will certainly be no exception as energy dropping
down the front side of the amplifying West Coast ridge will dive out
of The Rockies and across the Southern Plains where a significant
late winter storm will develop.
The storm system is forecast to spin up in the Lee of the Colorado
rockies Monday night...track across the Southern Plains on Tuesday...
then lift to the northeast across the Ohio and Tennessee valleys
Tuesday night and Wednesday. A fresh push of cold air will arrive
just ahead of this system with temperatures dropping to well below
average once again for Wednesday through the end of the week. There
will be a chance of light snow on Tuesday and Tuesday night with
moisture lingering behind a cold front and ahead of the eastward
push of low pressure toward the southern Appalachians.
00z European model (ecmwf) and GFS tracks remain well south of our region with little
significant impact to our forecast area. Best chances for
accumulating snow still look to be across the southern tier and
Finger Lakes regions. There still remains some question regarding
track and timing. All possibilities remain on The Table at this
point for western and central New York from dry and cold to a significant
snow event. Will continue to mention the potential in the severe weather potential statement for
now. It will likely still be several days before any sense of model
Surface ridging will follow the coastal middle Atlantic storm and will
crest across the eastern Great Lakes and New England during the end
of the week...with clearing skies Thursday night through Friday.
Aviation /09z Saturday through Wednesday/...
for the 06z tafs VFR flight conditions were found across the region
as high pressure and broad subsidence and drying slips eastward.
This will allow for a weak cold front with some high cloudiness to
advance southeastward towards the region through the overnight
hours...with ceilings lowering to low end VFR by daybreak. A weak cold
front will cross the region with a few stray snow showers. Generally
VFR visibilities will prevail though some MVFR visibilities in snow is possible
across the southern tier. MVFR ceilings tomorrow will gradually lift
back to VFR by the late afternoon or evening hours tomorrow.
Sunday and Monday...VFR.
Tuesday...MVFR in snow showers.
Wednesday...MVFR/IFR in snow.
a cold front will cross the lower lakes this morning with light to
moderate northwest winds behind it. Winds and waves are expected to
remain below Small Craft Advisory criteria. A weak ridge of high
pressure will build across the lower lakes briefly Sunday morning
before a warm front pushes east across the area Sunday night. Winds
will become southwest and increase again Sunday night and Monday.