Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 241800

Area Forecast Discussion
National Weather Service Buffalo NY
200 PM EDT Mon Oct 24 2016

Cold northwesterly flow will result in cloudy skies and below
average temperatures into Wednesday along with some scattered lake
effect rain showers. A low pressure system tracking out of the
Midwest is then expected to cross the lower Great Lakes Thursday,
bringing widespread rainfall. Another round of rainfall will be
possible this weekend, as another low pressure system drops across
the region.


IR/WV satellite imagery shows a subtle wave and area of enhanced
moisture over Lake Ontario. As this feature moves east of Lake
Ontario this afternoon, expect scattered lake effect rain showers
downwind of the lakes to increase in coverage into this evening.
Cooler air arrives aloft behind the wave, with 850 mb temps down to -
4C or colder overnight. Equilibrium levels will rise to around 10kft
as the cooler air aloft arrives, and added synoptic moisture from
the wave combined with an upstream lake connect should be enough to
sustain some lake showers. Lake effect showers are near the
Rochester Metro off Lake Ontario, and near the Chautauqua ridge off
Lake Erie this afternoon and evening. Behind the subtle wave passage
tonight, winds will bring the scattered showers back westward toward
the Niagara Frontier an northwestern PA before diminishing into the
day Tuesday. By tonight, temperatures overnight toward early Tuesday
morning may finally support some wet snowflakes in any showers over
higher terrain, however little if any accumulation is expected.
During the day Tuesday, drier air will build into the region,
combined with diurnal heating will help disrupt and break apart any
lingering lake effect.

Temperature-wise, he cold advection will be more noticeable tonight,
as readings fall into the 30s, with lower 30s across the North
County. Temperatures will remain crisp on Tuesday, with highs only
in the low to mid 40s.



A deepening storm system over the Midwest states on Wednesday will
shift across OH Wednesday night. This will bring an increase in
cloud cover and chances of rain showers over and west of the Genesee
Valley. While showers that arrive should mainly be in the form of
rain, there is a slight chance for some wet snow mixing in across
the higher terrain of the Southern Tier into the Bristol Hills.

The storm system will track right over Buffalo on Thursday with a
sharp shortwave trough aloft and strong 50kt low level jet driving a
likely probability of widespread rain showers. The storm will then
transfer its energy to a coastal low over the Gulf of Maine Thursday
night. Wrap around moisture and continuing cyclonic flow will keep
chances of rain showers in play on the back side of the system.
Temperatures will run 10-15 degrees colder than normal which may
allow wet snow to mix with rain showers across the Tug Hill region
Thursday night.


A negatively tilted midlevel trough will deepen enough to generate a
stacked low in the vcnty of northern New England/Maine on Friday.
This will continue a cyclonic/northwest flow of moist chilly air
over our region on the back side of the low with chance POPs for
scattered showers. A minimal lake response should enhance coverage
and possibly the intensity of some of these showers southeast of
Lake Ontario. Weak ridging is forecast to quickly push east across
the Lower Great Lakes Friday night with a short window of dry time

00z guidance is in better agreement with EC and GFS showing another
compact fast moving shortwave trough quickly dropping across the
Great Lakes. This should drive another low and round of widespread
showers for Saturday. Have kept chance POPs due to uncertainty in
the exact timing.

On Sunday weak ridging will shift across our region from the
central/northern plains states with any lingering showers tapering
off. A wavy zonal midlevel flow will help return temperatures back
toward normal late October levels through the weekend.


Persistent cold cyclonic northwesterly  flow across the Great Lakes
will continue to generate plenty of VFR cigs across the forecast
area through the TAF period, and a few lake effect rain showers will
be possible at times across the far western Southern Tier, as well
across areas south of Lake Ontario. Cigs may drop to MVFR in these
showers, but otherwise cigs will remain VFR elsewhere through the
TAF period.


Tuesday and Tuesday Night...Mainly VFR.
Thursday...MVFR/IFR with rain showers likely.
Friday...MVFR with a chance of lake effect showers.


Cold air advection in the northwesterly flow will keep a stiff
breeze in place on the lakes into Tuesday. Small craft advisories
remain in effect, as northwesterly winds 15 to 25 knots will keep
waves along the south shores of the lakes.

The brisk northwesterly flow is expected to persist into Tuesday
evening, at which point a broad surface ridge extending from a high
centered over James Bay progresses across the lower Great Lakes,
bringing another short-lived respite from small-craft advisory
conditions. Expect easterly flow to develop Wednesday and freshen
into Thursday, as another low pressure system tracks out of the
Midwest and across the lower Great Lakes.

High pressure will briefly ridge across the lake on later Tuesday
but another fast moving storm system will arrive Wednesday night
into Thursday.


MARINE...Small Craft Advisory until 9 AM EDT Tuesday for LEZ040-041.
         Small Craft Advisory until 6 PM EDT Tuesday for
         Small Craft Advisory until 9 AM EDT Tuesday for LOZ045.



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