Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Buffalo New York
647 PM EST Sat Nov 28 2015
high pressure will build across the region through Monday which will
bring cooler temperatures...but still not far from average for the
end of November. Then low pressure will lift across the Great Lakes
with rain and warmer temperatures Tuesday...followed by cooler
temperatures and some snow showers behind the system.
Near term /through Sunday/...
no changes to the forecast this
evening...other than to bump sky cover up a tad. It is still cloudy
over much of the County Warning Area this evening...with clearing slowly edging
southward from Canada. Cool northerly flow will maintain clouds
through much of the night. Previous Disco below...
The big forecast question is cloud cover...with satellite trends
suggesting that most guidance has been too quick to clear skies out.
Although middle-levels will dry out considerably...there will be
shallow low level moisture which is trapped beneath an inversion.
NAM BUFKIT and the hrrr capture this moisture...but this guidance is
sometimes too moist in the boundary layer. In this case...the
NAM/hrrr guidance has the best handle on the current conditions the
forecast will favor this more pessimistic guidance. Skies should
gradually clear from north to south tonight...however southern
portions may remain cloudy all night...with areas of clouds possible
an all areas south of Lake Ontario. Forecast confidence in sky cover
This will impact low temperatures...since cloud cover would prevent
radiational cooling. With a partial clearing expected in most
areas there should be at least some radiational cooling with the
coldest temperatures expected across the Eastern Lake Ontario
region where skies should clear out and allow temperatures to drop
into the upper teens to lower 20s. Elsewhere lows should mostly be in
the upper 20s...but possibly a few degrees cooler if there is any
clearing. Also...if skies do clear out it is possible that fog and
low stratus will develop in spots.
Sunday should be a dry day...with modest daytime mixing likely to
mix out the shallow low level moisture in many areas. The exception
may be near the south shores of Lake Ontario where most guidance
hangs onto at least some low moisture...and some high resolution
guidance forecasts some light quantitative precipitation forecast. Moisture does not appear to be
deep enough to support precipitation...however light quantitative precipitation forecast can
sometimes be a signal by model guidance that there will be low
stratus. Otherwise temperatures will continue to be on the cool side
with highs in the upper 30s to around 40.
Short term /Sunday night through Tuesday night/...
Sunday night through Monday night will feature seasonable
temperatures with dry conditions. High pressure will move eastward
across eastern Ontario and Quebec to northern New England. The
movement of the high will shift wind direction from northerly to
easterly and dry air associated with the high pressure cell... only
about 0.15 inch precipitable water... keep clear or nearly clear skies through this
period. The cool and dry air will limit high temperatures to the
upper 30s to lower 40s each day.
Nighttime lows will be slightly below normal given the optimal
radiational cooling with a very dry airmass in place. This will
promote lows in the 20s... and perhaps some upper teens in the north
country Sunday night. Monday night will run above normal as low-
level return flow starts to develop ahead of the next approaching
storm system...lows will be in the lower 30s from The Finger lakes
to Lake Erie and in the lower to middle 20s across the north country.
Cut off upper level low across the upper Midwest on Tuesday will
have a rapidly occluding surface low nearly beneath it...and a
pocket of cold air sweeping southeastward across the plains. This
will push a cold front through the region on Tuesday night. A surge
of moisture ahead of the front...precipitable water exceeding an inch...will provide
a significant source for rainfall starting middle morning on Tuesday.
Expect a steady rain through much of the day on Tuesday...continuing
through Tuesday night. Rainfall totals will range from near an inch
across the Lake Ontario basin to a quarter inch across the southern
tier. Temperature will also rise accordingly with high temperatures in the
middle 40s to lower 50s across the region.
Long term /Wednesday through Saturday/...
the cut-off low presently over the Great Basin will finally be on
the move eastward across the Central Plains by Monday and across the
Great Lakes by Tuesday. A warm front will lift northward across the
forecast area ahead of the approaching low... with an ample
subtropical moisture tap ahead of the closed low. The warm front /
developing low level jet should help to focus a band of rainfall that will
lift across the region on Tuesday. Behind this warm frontal passage
we will be in the warm sector with high temperatures pushing into
the lower 50s on Tuesday. The by Tuesday evening or into Wednesday
expect a cold front to push across the region from west to east with
a another batch of rainfall. While the overall track and timing
between the GFS/ec and their ensembles has been improving... there
remains about a 12 hour difference between the GFS and ec. The
ensembles / especially the ec ensembles/ depict an interesting bi-
modal difference in the timing... with about half the members
bringing the cold front through late Tuesday like the GFS and the
other half hold it back until Wednesday like the operational ec...
with few ensembles in The Middle Ground.
Regardless of the exact timing... by Wednesday into Wednesday night
expect lake enhanced showers to develop northeast of the lakes and
then settle east of the lakes into Thursday morning. Given the cut-
off nature of this low... there is no additional cold air tap from
higher latitudes... and models are only depicting 850 mb temperatures down
to about -4 to -7c in the core of the low. These marginal
temperatures will be enough to kick off lake enhancement over the
48f lake surfaces... however... expect mainly the higher hills south
of Buffalo and east of Lake Ontario will the only locations that
could really See Lake showers mix with or change over to snow
Wednesday into Thursday morning. This should result in some light
snow accumulations over the higher terrain south of Buffalo and east
of Lake Ontario by Thursday morning.
At this point... it is not looking great for Buffalo to see its
first measurable snowfall of the season with this storm... which
takes US through December 2nd and 3rd (although I would not rule
it out yet). The record latest measurable snowfall at kbuf is
December 3rd (which occurred in 1899). If we can make it through
this storm system without measuring 0.1 inches of snow... it could
actually be a while before we get another chance at snow. After
this storm system... ridging builds in across the eastern Continental U.S.
Again... with the highest 500 mb height anomalies from the Great
Lakes north to the Hudson Bay from the second half of next week
right through the weekend. Longer range ensembles (gefs through
360hrs and the cfs) indicate that this may actually become a
fairly persistent feature that could linger right through the 2nd
or 3rd week of December. Should this come to fruition... we would
see temperatures across the region remain at or above normal...
and any significant cold air remaining away from the Great Lakes
region... with perhaps only a few marginal chances at picking up
some measurable snowfall.
Aviation /00z Sunday through Thursday/...
at 00z expansive MVFR
ceilings...and at times IFR ceilings were found across the taf region.
Cool...moist northerly flow will continue through much of the
night...with clearing edging southward slowly from the north. IFR
flight ceilings will continue across the hill of SW New York state...while across
kbuf some intermittent IFR ceilings may occur before skies clear.
As the skies do clear there may be some patches of fog that form
later overnight...mainly south of Lake Ontario.
High pressure will continue to drop southward from Canada Sunday and
Sunday night. There may be Low Lake effect clouds over Lake Ontario
Sunday...with at times MVFR ceilings nearing kroc and kiag. As these
diminish expect then VFR flight conditions...with the exception of
southern tier fog to prevail through Sunday night.
Monday night and Tuesday...rain. Mainly MVFR.
Wednesday...mainly MVFR. Rain or snow showers likely.
Thursday...VFR/MVFR. A chance of rain or snow showers.
high pressure will build into the lower lakes through Sunday and and
then drift into New England on Monday. This will result in light
winds and flat wave action through Monday. Low pressure will track
across the Great Lakes middle week which will cause southerly winds to
pick up ahead of the system...and then northwesterly winds behind
it. This may require small craft advisories for some of the waters.