Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Buffalo New York
750 am EDT Tuesday Oct 21 2014
low pressure will slowly cross western New York today while
producing occasional showers. The low will then Transfer to just off
the middle-Atlantic coast by Wednesday and shift north along the East
Coast through the week while continuing plenty of clouds and showers
across the northeast. Temperatures will remain on the cool side
through most of the week before warmer and drier weather develops
for next weekend.
Near term /through tonight/...
surface analysis this morning shows the center of low pressure over
the western end of Lake Ontario. Satellite and regional radars
showing plenty of moisture and rain showers surrounding the center
of this low. The bulk of shower activity is found shifting east
across the Genesee Valley toward The Finger lakes associated with
warm advection and synoptic lift ahead of the surface low and a
sharpening middle-level trough.
The surface low will slowly drift southeast across western New York
this morning as it transfers toward the middle-Atlantic coast by
tonight. The middle level trough will also begin to develop a closed
circulation right over the lower Great Lakes. A lull in shower
activity will occur as the center of the surface low crosses the
region. Showers will then increase again across western New York this
afternoon with northwest flow setting up behind the surface low.
While the forcing and moisture coming together yield a high
probability of rain through today...the transient and complex nature
of forcing with the low crossing directly overhead will make timing
and placement of the periods of enhanced rain difficult at best.
With this in mind have continued with the wording of occasional
Tonight the surface low transfers to just off the middle-Atlantic coast
as this occurs the better moisture and synoptic lift will also shift
to the southeast with the low. Wrap around Atlantic moisture will
continue to work across the lower Great Lakes under northerly flow and
upslope across western and central New York. Expect that showers
will taper to just light rain/drizzle overnight with skies remaining
Rainfall amounts will be tricky to place as well...with higher
amounts remaining relatively localized. In general expect additional
amounts of a third to a half on an inch in most areas through tonight.
Extensive cloud cover will keep a small diurnal range in
temperatures today with highs rising to around 50 in most areas.
Tonight the northerly flow will advect some cooler air across our
region with lows expected to fall to around 40.
Short term /Wednesday through Thursday night/...
low pressure will drift off the middle-Atlantic coast and towards Cape
Cod through the period. Broad cyclonic flow around this large system
will encompass much of the northeast and maintain an abundant flow
of Atlantic moisture across the region that will be compounded by
northerly synoptic flow off the Great Lakes to produce an extended
period of dreary Fall weather across western and north-central New
York. The light rain and drizzle will be most acute south of Lake
Ontario where upslope flow and moisture advection off the lake will
be most persistent while eastern portions of the forecast area not
subject to the northerly onshore/upslope flow off of Lake Ontario
should see periods of showers given the closer proximity to the low
center and deeper synoptic moisture and shortwaves rotating around
the upper low center.
As we progress from Wednesday into Thursday...the probability of
accumulating precipitation will drop off south of Lake Ontario and
across western New York as the low off the East Coast drifts
northeastward and middle-level moisture declines considerably...however
moisture will still be plentiful enough in the low levels of the
atmosphere to maintain an extensive coverage of low stratus along
with areas of drizzle across much of western and central New York.
The areas that have the best shot at staying dry on
Thursday/Thursday night will be far southwestern New York...farthest
removed from the synoptic moisture as well as the influence of Lake
Temperatures throughout the period will run on the cool side
courtesy of the influence of the upper level trough as well as the
extensive cloud coverage that will blanket the region. This will
significantly mitigate diurnal temperature ranges with highs in the
upper 40s to lower 50s and lows ranging from the upper 30s across
higher terrain of the southern tier to the middle 40s near the lakes.
Long term /Friday through Monday/...
we should see gradual improvement by the weekend as the coastal low
off New England lifts northeast towards Atlantic Canada...taking
with it the bulk of the synoptic moisture. There will still be a
decent amount of cloud cover along with a chance of showers to
contend with on Friday as the low is pulling away from the
region...however we should see trend towards warmer and drier
weather over the coming weekend. The Fly in the ointment continues
to be a potent shortwave dropping across northern Ontario out of the
northwest territories. The European model (ecmwf) brings this shortwave and
associated showers and cool air perilously close to western/northern
New York Saturday night while the GFS keeps the feature well to our
north across Quebec and the Gem splits the difference...which is the
tack this forecast will take...going with low chance probability of precipitation and
temperatures that will run just a hair on the cool side of average
for late October.
As we open the coming week...models come back into good agreement in
bringing a broad upper level ridge across the Midwest with a
substantial surface ridge reflected across the lower Great Lakes and
the northeast. This should result in...wait for
it...sunshine...along with temperatures climbing at least into the
60s by Monday.
Aviation /12z Tuesday through Saturday/...
a mix of MVFR and southern tier IFR ceilings is found this morning in
the presence of low pressure and rain showers crossing the region.
Low pressure will be located over the western end of Lake Ontario
will shift south to the middle-Atlantic coast by tonight. Northerly
winds on the northern edge of the low across the Niagara Frontier
is allowing for lowering ceilings with mainly MVFR in place today and
lingering into tonight. Ceilings may intermittently drop in and out of
IFR but guidance suggests mainly MVFR ceilings. Occasional showers will
persist as well with br to produce areas of MVFR/IFR visibility into this
evening. Overnight IFR ceilings should be found from about kroc south
into the southern tier with light showers/drizzle.
Tuesday night...MVFR/IFR with occasional showers.
Wednesday through Friday...areas of MVFR with a chance of rain...
rain likely across central and northern New York.
low pressure over Western Lake Ontario this morning features a
period of relatively light winds right near the low center.
Northeast winds will increase on Lake Ontario today...then increase
further to around 25 knots this afternoon as the pressure gradient
quickly tightens behind the departing low. This will bring higher
end Small Craft Advisory conditions to the South Shore of Lake
Ontario through at least Wednesday. Northeast winds will also
increase enough to produce Small Craft Advisory conditions on Lake
Erie this evening through Thursday morning.
Marine...Small Craft Advisory from 8 PM this evening to 11 am EDT
Thursday for lez040-041.
Small Craft Advisory from 2 PM this afternoon to 11
am EDT Thursday for loz043.
Small Craft Advisory from 5 PM this afternoon to 11 am EDT
Thursday for loz044.
Small Craft Advisory from 11 am this morning to 11 am EDT
Thursday for loz042.