Irondequoit, New York Weather Forecast Discussion

865
FXUS61 KBUF 200745
AFDBUF
Area Forecast Discussion
National Weather Service Buffalo NY
345 AM EDT Sat Sep 20 2025
.SYNOPSIS...
Strong Canadian high pressure will settle from western Quebec to the
New England coastline this weekend. This will keep fair and largely
dry weather intact through the weekend...with just a couple isolated
showers possible across far western New York late Sunday. The cooler
airmass attendant to the high will also support some frost across
the North Country this morning and again tonight...before warmer
conditions return on Sunday. A broad...complex frontal system will
then slowly make its way east across the Great Lakes Monday and
Tuesday...while bringing an increasing likelihood of some rain
showers and a few thunderstorms.
&&
.NEAR TERM /THROUGH TONIGHT/...
During this period strong Canadian high pressure will settle from
western Quebec to New England. This will keep fair dry weather
intact across our region...with just a little passing cirrus at
times through today followed by a gradual increase in mid/high
clouds across western New York tonight as warm advection sets up
aloft.
The cool and dry airmass associated with the high will allow for
temperatures across the North Country to fall to the lower-mid 30s
and thereby support the development of some areas of frost through
sunrise this morning...for which a Frost Advisory remains in effect.
Elsewhere temperatures will mostly bottom out in the 40s...with some
isolated upper 30s across the Southern Tier. With temps aloft today
then running identical to those of yesterday...this afternoon`s high
temps should be along the same lines...ranging from the upper 60s
across the North Country to the lower-mid 70s across far western New
York.
As for the upcoming night...the aforementioned increase in mid/high
cloud cover and developing southeasterly return flow should result
in a milder night for areas south of Lake Ontario...with lows in the
mid 40s to mid 50s (warmest close to Lake Erie). East of Lake
Ontario skies will be clearer and the return flow will not develop
until later on in the night...likely allowing for enough of a window
for temps to again dip into the lower-mid 30s and allow for the
redevelopment of some patchy frost across portions of Jefferson and
Lewis counties...for which another Frost Advisory has been issued.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
An upper level ridge over the Northeast will shift east as a trough
digs into the Upper Great Lakes Sunday. Warm air advection and
daytime heating/mixing will result in temperatures quickly
rebounding, with highs in the low 80s across the Niagara Frontier
and Genesee Valley to the mid to upper 70s elsewhere. A few showers
may reach far western NY by afternoon, however probability is low. A
broad southwesterly flow will set-up across the forecast area Sunday
night through Monday night. This will open the door for greater
chances of showers and a possible thunderstorm through the start of
the work week. Initially, the best forcing will remain northwest of
the forecast area with widely scattered showers possible across far
western NY Sunday night. A surface low will move east across
northern Ontario and Quebec and drag a warm front across the
forecast area Monday. Low-level convergence and increasing moisture
will increase chances for showers from west to east Monday. Behind
the warm front, low to medium chances for showers and a possible
thunderstorm continues Monday night, however uncertainty is high.
Greatest chance for showers will be across southwest NY overnight.
The lack of deeper moisture and upper level support will limit
rainfall amounts across the region Sunday through Monday night.
Rainfall amounts will average 0.1-0.25" across the forecast area.
Based on the LREF/ensembles, there is a 30-40% chance of far
southwest NY getting over 0.50".
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
A weak cold front will be near the forecast area Tuesday. Daytime
heating and modest moisture may result in diurnal showers and
possibly a storm. Drier weather is forecast mid-week as a ridge
builds over the area. A closed low over the central Mississippi
Valley may move east through the end of the work week. This could
draw much needed Gulf moisture into the region with increasing
chances for showers and thunderstorms Thursday through Friday.
Temperatures will average near to above normal, with highs in the
low to mid 70s and overnight lows in the 50s.
&&
.AVIATION /08Z SATURDAY THROUGH WEDNESDAY/...
Canadian high pressure settling from Quebec to New England will
provide our region with widespread VFR conditions through
tonight...with just some patchy fog and associated restrictions
possible within the Southern Tier river valleys early this morning.
Winds will pick up a bit out of the east-northeast during the
day...supporting some gusts to 20 kts or so at both KBUF/KIAG this
afternoon.
Outlook...
Sunday...VFR.
Sunday night...Mainly VFR with scattered to numerous showers and a
couple isolated thunderstorms developing across western New York.
Monday and Tuesday...VFR/MVFR with showers likely along with a few
thunderstorms.
Wednesday... VFR/MVFR with a chance of showers.
&&
.MARINE...
Winds will freshen again out of the east-northeast today as the
pressure gradient across the Lower Lakes tightens in response
to high pressure settling into southwestern Quebec. This will
bring a period of advisory-worthy conditions to southwestern
portions of Lake Ontario today... before winds weaken/veer more
southeasterly tonight as the surface high slides out across New
England.
A moderate southeasterly flow is then expected on Sunday...with
winds then veering more southerly and picking up a bit across
eastern portions of both lakes Sunday night. This being said...
conditions should remain below SCA levels Sunday and Sunday
night...with the greatest wave action being directed across Canadian
waters.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...Beach Hazards Statement through this evening for NYZ001.
     Beach Hazards Statement through this afternoon for NYZ002.
     Beach Hazards Statement until 2 PM EDT this afternoon for
     NYZ003.
     Frost Advisory until 8 AM EDT this morning for NYZ007-008.
     Frost Advisory from midnight tonight to 8 AM EDT Sunday for
     NYZ007-008.
MARINE...Small Craft Advisory until 11 PM EDT this evening for LOZ042.
         Small Craft Advisory until 2 PM EDT this afternoon for
         LOZ043.
&&
$$
SYNOPSIS...JJR
NEAR TERM...JJR
SHORT TERM...HSK
LONG TERM...HSK
AVIATION...JJR
MARINE...JJR

NWS BUF Office Area Forecast Discussion