Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 212011
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
311 PM EST Tue Feb 21 2017

.SYNOPSIS...
A weak frontal boundary will push across our region this evening
with some shower activity...then fair weather will return for
Wednesday and Thursday. Temperatures will remain well above normal
through the end of the work week...particularly on Friday when parts
of the region will flirt with 70 degrees. A strong cold front will
cross the area late Friday night with notably colder weather
returning for much of the weekend.

&&

.NEAR TERM /THROUGH WEDNESDAY/...
An elevated frontal boundary stretching from southern Ontario to
western Lake Erie at 19z...will cross our forecast area early
tonight. While there is a serious lack of baroclinicity with the
subtle boundary...there will be some added lift from a passing 110kt
h25 jet. This jet was analyzed over Lower Michigan this morning and
will be cruising across southern Ontario at the time of `fropa`.
This will place our region under the right rear `entrance` region
during the evening hours and will offer the bulk of the lift for the
upcoming period of showers.

While there will not be a lot of overall lift...the airmass will be
sufficiently moist to support showers that could add up to as much
as a tenth of an inch. The AMSU blended total pcpn product shows a
plume of 1" inch PWAT values streaming northward from the GOMEX.
This narrow...but moisture rich band will accompany the
aforementioned frontal boundary.

Temperatures tonight will remain well above freezing...with mins
ranging from the mid-upper 30s to the mid 40s over the west.

While a fair amount of the mid level moisture will move out of the
area on Wednesday...there will still be near saturated conditions
below 6k ft. This will retard the speed of the clearing...with local
lift from orographics possibly leading to some morning sprinkles.
Otherwise...it will be a very mild day with the mercury climbing to
the lower 60s across the bulk of western New York and into the lower
50s across the North Country.

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/...
Well above normal temperatures will continue through the second half
of the week ahead of a storm system which will arrive by Saturday.
Southerly flow wrapping around a Bermuda High and ahead of a
developing storm system over the central portion of the county will
boost temperatures about 20 degrees above normal on Thursday and 30
or more degrees above normal on Friday. Readings on Friday will run
very close if not break record High Temperatures.

Outside of the warm temperatures chances for showers and eventually
maybe even a thunderstorm will mainly reside along passing frontal
boundaries. On Wednesday night, a southwesterly low level flow will
develop ahead of a weak low pressure system passing north of the
Great Lakes. Very weak warm advection and synoptic lift aloft will
introduce a chance of a shower ahead of a weak cold front trailing
the surface low. The front will approach western NY Wednesday night
then cross the forecast area on Thursday with mainly a chance for
some scattered showers. Temperatures as mentioned above will run
above normal with lows only slipping back into the 40s Wednesday
night then rising into the 50s on Thursday ahead of this front with
the best chance for some low 60s across the Finger Lakes.

High pressure will the ridge south across much of the forecast area
on Thursday night behind the cold front with only a chance of a
shower toward the PA border where the cold front may stall. On
Friday and Friday night the Central Plains storm system will lift
toward the western Great Lakes. A warm front ahead of this system
will cross western and central NY during the day with likely POPs for
rain showers. 850mb temps then rise to near +10C in the wake of the
warm front where surface highs will make a run toward the 60s and
even 70 in a few spots. A few of the SREF members even show a high
warmer than 70 for Buffalo on Friday. Have gone just shy of 70 for
Buffalo and Rochester and just shy of 60 in Watertown. These
forecast highs would break a record in Buffalo and Watertown and run
just short of a record high in Rochester if verified. Southerly
winds will be a bit breezy but any stronger winds aloft will hold
off until behind the cold front on Saturday. There could also be a
slight chance of a thunderstorm on Friday afternoon/evening as the
12z GFS shows some weak surface CAPE and negative LIs working over
western NY in the warm sector ahead of the cold front. Temps Friday
night will run very mild ahead of the cold front only dipping down
into the upper 40s if not low 50s.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
When we open this period Saturday morning...a strengthening sub
990mb low will be pushing northeast from Lake Huron while its
powerful cold front will be bulldozing across western and north
central New York. The accompanying rain showers will be accompanied
by winds of at least 25 to 40 mph with the frontal passage...then
after a couple hours where winds will subside a bit...winds will
ramp back up...possibly as high as 50 mph. The storm track...
negative tilt to the supporting mid level trough...and suggested
subsidence all favor at least advisory criteria winds. The only
thing missing is a significant low level jet. Stay tuned.

Strong cold advection on the backside of the exiting cyclone will
send H85 temps to as low as -15c Saturday afternoon into MOnday.
This will be more than cold enough to promote lake effect snow
showers east of both lakes..with significant accumulations possible
east of Lake Ontario where an upstream connection and full fetch
will be likely. Outside of the lake effect areas...Sunday and Monday
will feature partly to mostly cloudy skies and scattered light snow
showers.

After temperatures fall from 50 Saturday morning in the wake of the
front...max temps will be in the mid 30s on Sunday and close to 40
for most areas on Monday. Mins through the period will be in the
20s.

&&

.AVIATION /20Z TUESDAY THROUGH SUNDAY/...
VFR conditions will be in place through the rest of afternoon...
although the cirrus and alto-cu will gradually lower to strato-cu by
this evening. Lowering cigs will eventually lead to MVFR conditions
this evening... with most areas experiencing MVFR cigs through the
night. Parts of the Srn Tier and Finger Lakes region will have IFR
cigs late tonight and early Wednesday.

On Wednesday...the relatively low cigs will linger through a
good part of the morning in most areas before rising to VFR
levels.

Outlook...

Thursday...Mainly VFR.
Friday and Saturday...Periods of rain showers with MVFR and
local IFR. Windy on Saturday.
Sunday...Mainly VFR but IFR to MVFR in lake effect snow
southeast of both lakes.

&&

.MARINE...
A relatively weak pressure gradient with a neutral to warm temp
advective pattern will keep relatively light winds and manageable
waves in place across the Lower Great Lakes tonight through
Wednesday night.

The next real time of concern will be late Friday night and Saturday
when a powerful cold front will cross the Lower Great Lakes.
Strong...possibly gale force winds...will be found in the
wake of the front Saturday and Saturday night.

&&

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

&&

$$

SYNOPSIS...RSH
NEAR TERM...RSH
SHORT TERM...SMITH
LONG TERM...RSH
AVIATION...RSH
MARINE...RSH



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