Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 080030
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
730 PM EST Sun Mar 7 2021

.SYNOPSIS...
Dry but cold temperatures will continue through tonight, before
day to day warming of our airmass leads to well above normal
warmth by mid week. A slow moving boundary will allow for
several opportunities for rain showers toward the second half of
the week. Above average temperatures in combination with runoff
from snowmelt, and eventually some rain later in the week will
cause rivers and creeks to rise.

&&

.NEAR TERM /THROUGH MONDAY/...
Aside from some stubborn localized lake clouds across the Niagara
Frontier this evening, mainly clear to partly cloudy skies and good
radiational cooling conditions will allow for one more cold night
with below normal temps tonight, although warmer air will be
starting to move in aloft over western NY later tonight as a sign of
what`s to come. Before that though lows will drop back into the
teens across the lake plains, with single digits across the higher
terrain. Even sub zero readings possible for the Tug Hill and
western Dacks.

Surface high pressure will settle southward across the Southeast
Monday. Meanwhile, warm advection mid and upper level clouds
associated with a weak and mainly dry warm front will move into
western and northcentral NY, with the best chance for a stray rain
or snow shower east of Lake Ontario later in the day. Otherwise, the
start of our day to day warmup begins as temperatures rise into the
low to mid 30s east of Lake Ontario, with low to mid 40s across the
remainder of the area.

&&

.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/...
A weak warm front will be quickly followed by a weak cold front
which will wash out as it moves into the area Monday night.
This bring some light (mainly) snow showers to the North Country
closest to its supporting shortwave. Otherwise, suspect
mesoscale guidance is overdone with its upslope QPF but there
will be some clouds with a widely scattered rain shower possible
elsewhere. Lows Monday night will range from the lower to mid
30s south of Lake Ontario to the mid to upper 20s across the
North Country.

High pressure will build back into the eastern Great Lakes on
Tuesday, with dry weather and clearing skies. Highs Tuesday will
reach the upper 40s to lower 50s in Western NY, and low to mid 40s
for the North Country.

High pressure will remain centered off the southeast coast
Wednesday. Dry weather will continue, with just a modest increase in
mid/high clouds during the afternoon ahead of the next system.
Southwest flow and warm advection will ramp up over the Ohio Valley
and New England, allowing a much warmer airmass to move into our
region. Highs will reach the upper 50s to lower 60s for much of the
area, with mid 50s for the North Country. A SSW wind direction will
keep most of the lake induced cooling on the Canadian side of the
border.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
A mid level trough will advance from the Northern Plains Wednesday
night to the Great Lakes by Thursday night. Deep moisture will
gradually increase Wednesday night, with a pre-frontal trough
possibly bringing a few rain showers overnight. A better chance
of rain showers will arrive Thursday night as a cold front and
possibly a wave of low pressure slowly approaches and then
crosses the eastern Great Lakes. 12Z ECMWF/GFS/GGEM guidance has
trended slower, suggesting much of Thursday may remain dry. If
this happens, then Thursday will be as warm or warmer than
Wednesday. However the wind direction will likely be more
southwest than Wednesday, bringing more lake cooling to areas
northeast of the lakes including Buffalo. Showers will likely
move through Thursday night before tapering off Friday morning.

Colder air will filter back into the region Friday as cold advection
increases behind the cold front and the mid level trough reaches the
eastern Great Lakes. The airmass rapidly dries out Friday night
and Saturday behind the cold front, so despite colder northwest
flow expect mainly dry conditions. Highs by Saturday will be
back in the upper 30s to mid 40s before another cold front is
forecast to push southward across the area by Sunday.

&&

.AVIATION /01Z MONDAY THROUGH FRIDAY/...
VFR flight conditions and mainly light winds will persist through
the TAF period owed to high pressure crossing the region tonight.
Aside from some stubborn lake clouds across the Niagara Frontier
producing localized low VFR CIGS (~040) this evening at KBUF and
KIAG, expect mainly clear to partly cloudy skies.

Mid and upper clouds will move into the region Monday as warmer air
starts to move in.

Outlook...

Monday Night through Wednesday...VFR.
Wednesday night and Thursday...Mainly VFR. A chance of showers.
Thursday night and Friday...VFR/MVFR. Showers likely.

&&

.MARINE...
High pressure will build across the eastern Great Lakes tonight with
light winds and negligible waves through Monday. A weak cold front
will cross the Lakes Monday night with some elevated winds and waves
briefly late Monday night and Tuesday morning, especially across
southeastern Lake Ontario. High pressure will then build back in
allowing winds and waves to lessen through Wednesday.

Pressure gradient will tighten Wednesday night in the wake of a warm
frontal passage, with strengthening southerlies possibly increasing
enough to bring the next round of low end Small Craft Advisory
conditions.

&&

.HYDROLOGY...
A significantly warmer pattern will start on Tuesday and this will
result in increasing snow melt and associated run-off. There is
still significant snow pack in place, especially across higher
terrain and in the woods. The warmest temperatures will be on
Wednesday and Thursday, with showers Thursday through Friday
morning adding some additional run-off in addition to the snow
melt.

The first concern is the risk for ice jam flooding since this
could potentially occur much earlier than flooding due purely
to high flows. The greatest risk for ice jams is mainly near
where several Buffalo area creeks flow into the Buffalo River,
which is a common location for ice jams. High flows from last
week left ice jams in place, and cold weather since then has
frozen these in place. Flows on the creeks will rise Tuesday
evening in response to warmer temperatures, before leveling off
Wednesday morning. More significant rises can be expected
Wednesday evening through Thursday night when there will be a
prolonged period of temperatures in the 50s and 60s. This will
eventually flush out the ice jams and pretty much any ice in
place, but the big question is how firm the ice jams are.
Gradual melting from modest rises on Monday into Tuesday may
help erode some of the ice before the highest flows start.
However the longer existing ice jams hold, the greater the risk.
Ice jam flooding concerns are greatest Tuesday night through
Wednesday night - but before the highest flows are expected.

There is also a risk for flooding from high flows. The timing on
this would be considerably later, with the highest flows on
faster responding creeks likely to be on Thursday with slower
responding river flooding possibly extending into Friday and
Saturday. Latest model guidance shows a longer period of warm
weather, and also some risk of more QPF (half inch or so) since
the front will be slower to move through. This uncertainty is
reflected in the MMEFS ensembles which show a risk for flooding
in the Allegheny and Black River basins, in addition to the
Buffalo creeks.

Probabilities for individual forecast points to reach flood
stage are still low (generally 10-50 percent) but if these model
trends continue a Flood Watch may be needed for this in addition
to the ice jam risk. Timing is tricky because the risk starts
with ice jams, and then varies by basin with much later start
times in the Black River basin which has considerably more snow
pack in place but is also slower to warm.

It does appear that the warm up this week will melt most of the
snow and ice south of Lake Ontario.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...None.
MARINE...None.

&&

$$

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



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