Forecast Discussion

Forecast Discussion for BUF NWS Office
000
FXUS61 KBUF 262217
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
517 PM EST Sat Nov 26 2022

.SYNOPSIS...
A storm system organizing over the southern plains this evening
will track northeast across the Ohio Valley late tonight and Sunday
morning...then will move directly over our forecast area Sunday
afternoon and evening. This will result in a widespread soaking rain
that will spread across our region from southwest to northeast to
close out our weekend. After some leftover showers Monday morning...
elongated high pressure will then offer much improved weather for
Monday afternoon and Tuesday.

&&

.NEAR TERM /THROUGH SUNDAY/...
A fairly strong mid level ridge crossing our region tonight will
continue to support fair dry weather...but cirrus well in advance of
the next storm system will thicken overhead during the course of the
night.

The aforementioned storm system is in the process of organizing over
the southern plains this evening. As we progress through the
overnight into Sunday morning...a corresponding deepening sfc low
will track northeast across the Ohio valley and will take aim on the
Lower Great Lakes. The area of low pressure is forecast to move
directly across our forecast area. Since this will be a `warm`
southern stream system...all of the precipitation that will move
into our forecast area will be in the form of rain.

Fairly rich GOMEX moisture (PWAT 1-1.25") ahead of the system will
be lifted by a combination of a strong coupled H25 jet and
strengthening H925-700 frontogenetic forcing to produce several
hours of steady rain...which could be moderately heavy at times. The
rain will move in from the southwest...overspreading the western
Southern Tier by mid morning and the remainder of western New York
by the lunch hour before expanding to the Eastern Lake Ontario
region during the first half of the afternoon. All in all...it will
turn out to be a miserable day with widespread steady rain with
basin average rainfall ranging from a half inch over the far western
counties to a quarter inch across the North country. Note that
another quarter inch or so of rain is expected Sunday night.

&&

.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/...
Mid level shortwave and attendant surface low pressure system over
the lower Great Lakes Sunday evening will quickly move northeast to
near Nova Scotia by Monday morning taking associated deeper moisture
and forcing with it as we start the new work week. This will force
an attendant cold front through our region Sunday night bringing
another period of light rain Sunday evening into the early
overnight, gradually tapering off to mainly scattered light showers
by Monday morning in the wake of the cold fropa. Airmass will not
grow cold enough for much in the way of a lake response overnight,
however it will cool off enough to allow for some wet snow showers
to mix in across the higher terrain by later Sunday night. Best
chance for a slushy coating will be across the Tug Hill and western
Dacks by sunrise Monday morning. Another upper level wave and
attendant weak secondary cold front will quickly cross the area on
Monday. There will be decent forcing with these features, however
with limited moisture in place expecting just some scattered light
rain/wet snow showers mainly during the morning hours before drying
out from west to east as high pressure builds toward our area from
the west.

Progressive pattern continues with a ridge building in overhead
Monday night into Tuesday morning, before moving east into New
England Tuesday afternoon, then to near Nova Scotia Tuesday night.
Meanwhile a large mid and upper level trough will be deepening
across the upper Midwest and mid Mississippi Valley Tuesday night
and will be starting to show signs of taking on a negative tilt.
This will support a rapidly deepening area of low pressure that will
move northeast to somewhere near the SOO by Wednesday morning.
Plentiful moisture and strong forcing ahead of the system`s trailing
cold front will enter western NY during the second half of Tuesday
night, with some rain showers moving into areas from the Genesee
Valley westward by daybreak Wednesday. Winds will also be on the
increase later Tuesday night as well. More on these items in the
long term discussion.

Otherwise, expect high temperatures on Monday in the mid 30s to low
40s, with mainly 40s for Tuesday (some mid and upper 30s hanging on
across the higher terrain across the North Country). Lows Sunday
night and Tuesday night mainly range through the 30s, with 20s to
low 30s for Monday night.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
Wednesday and Thursday an energetic and increasingly negatively
tilted upper level trough will push from the Upper Mississippi
Valley to New England. Meanwhile at the surface...its initially
elongated attendant surface low will consolidate/deepen and track
from the Great Lakes across southeastern Canada.

As has been the case with this system...the latest model guidance
continues to exhibit run-to-run and model-to-model differences with
respect to the degree of phasing between a strong shortwave impulse
rounding the base of the main upper trough and a mid-level low
moving east across southern Canada...which in turn lead to notable
differences in the eventual strength...timing...and track of the
surface low. While the overall trend over the past 48 hours has
generally been toward a more distant track and/or weaker system...it
is noteworthy that the 12z GFS has trended back toward a stronger
overall system and closer track across Georgian Bay and Southern
Ontario/Quebec...which would be more favorable for a round of high
winds across our region were this to actually verify.

Digging a bit more into the forecast details...deep moisture and
strong forcing arriving across our area out ahead of this system
will act in concert with strong warm air advection to lead to
periods of rain and well above normal temperatures Wednesday...when
areas of favored southerly downslope flow will likely see highs
pushing 60 degrees. The strong cold front trailing from the low will
then plow across our region Wednesday night...with much colder air
and at least rather windy conditions ensuing for the rest of
Wednesday night and Thursday. The incoming colder airmass and
general westerly to northwesterly flow will also drive the
development of some lake effect snow showers east and southeast of
the lakes later Wednesday night and Thursday...however these still
look to be fairly short-lived as high pressure and much drier air
rapidly build into the region Thursday afternoon and night.

Friday and Saturday the surface ridge will slide off to our east...
while a zonal to weakly ridged flow develops across our region
aloft. This will lead to a return to milder temperatures for the
last two days of this period...with fair dry weather on Friday
possibly giving way to a low chance of rain showers on Saturday as a
weak low pressure system slides eastward across southern Canada.

&&

.AVIATION /22Z SATURDAY THROUGH THURSDAY/...
High pressure to the south and associated subsidence will provide
mainly clear skies through this evening. VFR flight conditions
through 12Z Sunday.

Rain will spread across the region during the day Sunday, with cigs
quickly lowering to IFR following the start of the rain. Easterly
surface winds climatologically favor IFR conditions at KBUF/KIAG/KROC.

Outlook...

Sunday night...Mainly IFR with periods of rain.
Monday...MVFR/IFR to VFR with lingering rain and snow showers.
Tuesday...VFR.
Wednesday...MVFR/IFR windy with rain.
Wednesday night...MVFR with rain or snow showers likely.
Thursday...VFR/MVFR. A chance of snow showers.

&&

.MARINE...
High pressure to our south that helped to generate gusty winds
across the region during the daylight hours is now working its way
off the Southeast coast. This will allow the corresponding sfc
pressure to relax throughout the Lower Great Lakes region with winds
and waves gradually lowering as we move through tonight. Small craft
advisories will drop off from west to east as a result.

While a deepening storm system will track directly across the Lower
Great Lakes on Sunday with periods of rain...winds and waves should
remain below SCA criteria. In its wake though...freshening winds
will likely require another round of SCA`s...mainly on Lake Erie for
Sunday night into Monday.

&&

.HYDROLOGY...
There is a limited risk for minor poor drainage flooding as well
as minor flooding along the Buffalo Creeks on Sunday into Monday.
It should be emphasized that while minor flooding is possible,
impacts will be very limited if flooding does materialize given
the relatively modest rainfall.

A significant portion of the snowpack from historic lake effect
snows last weekend has melted, with most of the region now back
to bare ground except for the hardest hit areas. Even in these
areas, snow depth has decreased significantly and a notable
portion of the snow water equivalent (SWE) in the snow has been
released. There is still enough SWE left to give some concern
across the Buffalo Southtowns and Buffalo area creek basins.

Rainfall amounts in the Buffalo Creeks basin will most likely be
around 0.6 inches. Above freezing temperatures will also continue
to gradually melt the remaining snow pack. Latest river forecasts
take these factors into account, and suggest that some creeks are
likely to reach or approach action stage Sunday into Monday. This
includes Cazenovia, Buffalo, Cayuga, and Ellicott Creeks. It`s
possible that one or more of these creeks will reach minor flood
stage, but this would likely require rainfall amounts to exceed
three-quarters of an inch. Even so, the impacts at minor flood
stage are limited, and the risk of this happening remains below
50 percent.

In addition to high flows on the creeks, there also may be some
minor poor drainage flooding in streets, especially where
snowbanks are blocking drainage structures.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...None.
MARINE...Small Craft Advisory until 10 PM EST this evening for
         LOZ042>044.
         Small Craft Advisory until 4 AM EST Sunday for LOZ045.

&&

$$

SYNOPSIS...RSH
NEAR TERM...RSH
SHORT TERM...JM
LONG TERM...Hitchcock/JJR
AVIATION...Apffel
MARINE...RSH
HYDROLOGY...Hitchcock

NWS BUF Office Area Forecast Discussion