Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Buffalo New York
1222 am EST Friday Nov 27 2015
a complex...slow moving cold front over the upper Great Lakes
will cross our region late Friday. This will bring an end to our
spell of October like warmth while producing several hours of
rain late in the day and during the evening. High pressure will
then nose from the northern plains across all of the Great Lakes
to provide US with fair and seasonably chilly conditions for
Saturday and Sunday.
Near term /through today/...
October like warmth will continue across the region into the day
Friday...as the combination of anomalously strong high pressure
southeast of Nova Scotia and a slow moving frontal boundary over the
upper Great Lakes will keep a strong southerly flow in place over
the lower Great Lakes. The staunch southerly flow will include 40kt
winds at 2k feet...which will not only advect 850 mb temperatures as high as 10c
over our region...but will also direct a rich moisture plume in our
direction. The latter will come into play later Friday into Friday
night. More on this in a moment.
Overnight...it will remain dry and almost balmy for late November
standards. Temperatures in most areas will remain steady or slowly
rise through the rest of the night...with middle to upper 50s on the
lake plains and upper 40s across the interior southern tier and
The complex slow moving front...which will be over southern portions
of Ontario and lower Michigan in the morning...will grudgingly push
southeast across our forecast area during the afternoon and early
evening. Given the anabatic nature of this frontal boundary...the
majority of the associated precipitation will fall in its wake rather than
ahead of it. Deep lift along and behind the front will be generated
from strong frontogenetic forcing along with some jet induced
lift from a passing 150kt h25 jet to our north. The warmer air
lifting over and northwest of the passing front should make the
rainfall fairly steady rather than showery as is often the case
with cold fronts...so have changed the wording to rain in areas of
Cat probability of precipitation.
Temperatures in most areas will once again climb to the vicinity of
60...especially over portions of The Finger lakes and Genesee
Valley. These temperatures will be roughly 20 degree f above normal late
Short term /tonight through Sunday night/...
the going forecast for this period looks perfectly reasonable this
evening...so no changes are necessary for this time frame.
Cold front will continue across New York state through Friday evening
with the bulk of the precipitation along and behind the front. With
precipitation expected to continue with the middle-level forcing behind
the surface front...and overall cooling in the column behind the
front...expect there will be a changeover to some wet snow by early
Saturday morning from north to south. Increasing cold air advection
and weakening middle-level ascent should quickly kill off the
precipitation after it mixes with or changes over to snow... thus
dont expect much if any snow accumulation or impacts. The best
chance at a slushy dusting of wet snow is in the north country...
where temperatures will cool the most and fastest behind the front
and where upslope northwest flow into the tug should help precipitation linger
just a bit longer.
Saturday will see a drying/clearing trend from north to south as high
pressure builds into the region. Temperatures will be much cooler...
with highs only in the middle 30s to low 40s. Clear skies and light
winds under the high pressure by Saturday night will set the stage
for excellent radiational cooling promoting lows in the 20s.
Looking further out in this period...high pressure over Ontario and
Quebec will maintain clear skies...cool temperatures and light
northerly winds Sunday and Sunday night. Expect high temperatures on Sunday
to not rise much farther than the upper 30s to lower 40s... and lows
on Sunday night to fall to the lower to middle 20s.
Long term /Monday through Thursday/...
the attention in the extended forecast turns to the cut-off low
ejecting out of The Four Corners region across the central Continental U.S.
By Monday and eventually across the North East by mid-week.
Early in the week ahead of the approaching low... shortwave ridging
builds across the forecast area with milder return flow working
northward into western New York. Expect a slow moderating temperature
trend for Monday and Tuesday... with highs back in the middle 40s to
near 50 by Tuesday. Models are improving in placement/timing of the
ejecting low... bringing best chance of rain showers across western
New York on Tuesday along the warm front and then again along the cold
front passage. Have likely probability of precipitation on Tuesday to reflect the much
improved consensus of GFS and European model (ecmwf).
As the low pivots across the Great Lakes into Wednesday... the in
situ cold air and moisture with the cut-off low (850 mb temperatures to
about -6c) should be cool enough to support lake effect showers east
northeast then east of both lakes Erie and Ontario. The marginal
forecast temperatures suggest the best chances at any snow
accumulations would be over the higher terrain east of the lakes.
The progressive nature of the ejecting low should allow the flow to
quickly turn northwest by Wednesday night into Thursday... keeping
any lake effect showers from having much time to linger over the
same locations. This will however return the region to cooler
temperatures with highs on Wednesday and Thursday in the 30s to low
40s and low temperatures in the lower 30s to middle 20s.
Aviation /06z Friday through Tuesday/...
strong high pressure anchored off the New England coast will keep
VFR conditions in place across our region overnight...although
surface winds will gust to nearly 30 knots at times. During times of
no surface gusts...some wind shear will be present at 1500-2000 feet
where a south to southwest flow will average 40 knots. Otherwise
middle/high clouds will thicken from west to east.
On Friday...a complex...slow moving frontal boundary will gradually
ease to the southeast across our region. This will lower ceilings to
MVFR levels during the afternoon...with fairly widespread rain and
continuing lowering ceilings resulting in IFR conditions for most areas
by late afternoon/early evening.
Friday night...IFR ceilings with mixed rain and snow ending.
Saturday through Monday...mainly VFR.
Monday night and Tuesday...VFR to MVFR with some showers likely.
a relatively tight surface pressure gradient between anomalously strong
high pressure centered southeast of Nova Scotia and a slow moving
frontal boundary over the upper Great Lakes will keep fresh to
strong southerlies in place into the day Friday. While the highest
waves will generally be in Canadian waters...small craft advisories
will remain in place during this time for the New York nearshore waters of
Lake Erie and also for Eastern Lake Ontario north of Mexico Bay.
A slow moving frontal boundary will settle across the lower Great
Lakes Friday afternoon. Winds will veer to the north in the wake of
the slow moving front...with winds possibly strong enough to warrant
fresh sca's for much of the remainder of Lake Ontario.
Light winds and negligible waves can then be expected across the
lower Great Lakes for Saturday and Sunday as high pressure will
build in from the northern plains.
Marine...Small Craft Advisory until 4 PM EST this afternoon for lez040-
Small Craft Advisory until 4 PM EST this afternoon