Area Forecast Discussion
Issued by NWS Buffalo, NY

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000
FXUS61 KBUF 011205
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
705 AM EST Wed Mar 1 2017

.SYNOPSIS...
Unseasonably mild air will remain across the region today, with
temperatures peaking in the mid 60s to lower 70s in most areas this
afternoon. Low pressure crossing Southern Ontario and its trailing
cold front will bring widespread showers and scattered thunderstorms
today. Following the cold front, much more typical late winter
temperatures and some limited lake snows will return for the end of
the week, before another warmup arrives in time for Sunday and early
next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
An extended region of low pressure will cross Southern Ontario this
morning, and move into Southern Quebec this afternoon and evening.
The low pressure will draw warm and more moist air across New York
State on southerly winds, which will prime the region for rain
showers and even some thunderstorms. A prefrontal trough moving east
over Lake Erie during the late overnight hours will cross our region
between the morning and early afternoon hours. This will be
accompanied by fairly widespread showers and embedded thunderstorms,
some of which could produce locally heavy rainfall and/or gusty
winds given available PWATs in excess of 1 inch and the strong wind
fields that will be in place aloft. Although the likelihood of rain
showers and scattered thunderstorms is high, the risk for severe
weather is limited to gusty winds accompanying the stronger
thunderstorms.

Following this first round of wet weather, a relative break in the
precipitation should ensue for the late morning to mid afternoon
hours, with some breaks of sunshine also possibly developing. In
conjunction with the mild airmass and further strengthening of the
low level southerly to southwesterly low level flow resulting in
good mixing, this should allow temperatures to surge into the mid
and upper 60s across most of the area, with highs in the lower 70s
more likely from the Genesee Valley eastward across the Finger
Lakes. These temperatures will be at or above record levels. The
coolest overall conditions will be found immediately northeast of
the lakes, where the increasingly onshore flow off the cold lake
waters will help keep highs confined to the upper 50s and lower
60s... and may also eventually induce temperatures to fall during
the afternoon.

By mid to late afternoon, the surface cold front and its parent mid
and upper level shortwave will be approaching our region. Increasing
large-scale forcing attendant to these features will interact with
our warm and moist airmass, with a second round of convection likely
initiating along a lake breeze boundary east of Lake Erie, then
intensifying and spreading northeastward across the remainder of the
region through the early evening hours. Dependent upon the exact
degree of destabilization realized prior to its development, this
second round of convection could well prove to be our best chance
for some stronger to potentially severe storms, which will certainly
remain possible given the very strong wind fields and resultant
vertical shear that will be in place aloft. With this in mind, SPC
has a marginal to slight risk of severe in place across much of our
area for Wednesday, with strong damaging wind gusts the primary
severe weather threat.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
The strong surface low over eastern Quebec Thursday morning will
quickly move east into the Canadian Maritimes through the day. Wrap
around moisture and weak ascent associated with the mid level trough
will still be in place early, but will quickly pull away by late
morning. Expect snow showers in most areas at daybreak, with the
best coverage across the higher terrain of the Chautauqua Ridge and
east of Lake Ontario from modest lake enhancement and upslope flow.
This may produce up to an inch of accumulation across higher terrain
in the morning, with a dusting elsewhere. All of this quickly ends
by afternoon with a return to at least some sunshine as a much drier
airmass quickly builds into the Lower Great Lakes.

Winds will remain strong in the morning with around 50 knots aloft
in the cold advection in the wake of the departing surface low. By
Thursday morning boundary layer flow will be veered westerly or even
WNW, which typically brings the strongest wind gusts to the
southeast corner of Lake Ontario, and also across the higher terrain
of the Finger Lakes and interior Southern Tier. A wind advisory will
remain in place in these areas through 18Z before winds taper off in
the afternoon as the pressure gradient and winds aloft relax.
Temperatures will be dramatically colder than today, with highs in
the lower 30s on the lake plains and upper 20s higher terrain.

Thursday night and Friday a deep longwave trough will take up
temporary residence across the Great Lakes and Northeast. A weak
clipper low will pass by to our south through PA. The 00Z NAM seems
way overdone with the intensity of this system, and have sided with
the much weaker GFS/ECMWF solutions. This may bring a few light snow
showers to the western Southern Tier, with a few snow showers
elsewhere possible in weak northwest flow lake effect. All of this
should remain very light, with any accumulations generally an inch
or less. Expect lows Thursday night in the lower 20s, with teens
across the North Country. Highs Friday will be in the mid to upper
20s in most areas.

Friday night the weak clipper moves off the east coast. Cold
northwest flow may support a few scattered snow showers, especially
southeast of the lakes but again amounts will be very light with the
dry nature of the airmass preventing a significant lake response.
Temperatures will be colder than we have seen in quite some time,
with lows in the lower teens in most areas and single numbers for
the North Country.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
A northwest flow will keep temperatures cold into Saturday and aid
in the continuation of some lingering light lake effect snow
southeast of Lakes Erie and Ontario. Temps will continue below
normal, with highs in the 20s for most.

Warm advection will increase Sunday as the mid level trough moves
east into the Canadian Maritimes and a ridge progresses east across
the Ohio Valley and Great Lakes. Light scattered snow showers are
possible in advance of a weak warm front that will cross the area on
Sunday, and snow will transition to rain as temps rise with passage
of the front. Another stronger warm front will bring a better chance
of rain showers by later Monday. Temperatures will warm to above
normal again for Sunday afternoon through Tuesday.

&&

.AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
During the day today, the initial round of showers and scattered
thunderstorms and attendant MVFR/localized IFR will press across the
region during the morning and early afternoon hours. There will be a
relative break in the precip and a general improvement to VFR is
expected for a time between late morning and mid afternoon, before a
second round of showers and scattered storms initiates to the lee of
Lake Erie in advance of an approaching cold front. This second round
of convection is then expected to expand northeastward and cross the
rest of the area through early evening, with another round of MVFR
and possible heavy rain/locally gusty winds. Meanwhile, any morning
LLWS will tend to relax by mid-late morning as winds aloft
temporarily diminish and surface winds increase, with increasingly
breezy to windy conditions then ensuing for the rest of the day as a
tightening pressure gradient sets up in advance of the approaching
cold front. The Southern Tier will remain in lower clouds with lower
range MVFR ceilings. The will be an overall improvement to VFR
across the remainder of the forecast area, although lower VSBY is
expected in the areas of moderate snow showers in the lee of the
Lakes.

Outlook...
Wednesday night, Very windy, with MVFR/IFR flight
conditions expected as early evening showers and scattered
thunderstorms give way to some snow showers.

Thursday and Friday...Scattered to numerous snow showers with areas
of MVFR/IFR.

Saturday...VFR/MVFR with a chance of snow showers southeast of Lake
Ontario.
Sunday...VFR/MVFR with a chance of rain and snow showers.

&&

.MARINE...
As low pressure tracks east across Southern Ontario province,
southerly winds will become westerly following the passage of an
attendant cold front. The cold air on these west winds will increase
wind speeds to gale force range on both Lakes Erie and Ontario this
evening through the late overnight on Lake Erie, and from this
evening through Thursday afternoon on Lake Ontario. Winds will
lessen on Thursday night, go through a cycle of light night winds
and brisk afternoon winds during Friday and Saturday, then southeast
to east on Sunday in anticipation of the next low pressure system.

&&

.HYDROLOGY...
The Black River will maintain high levels through the weekend. No
flooding is expected through this afternoon with the river expected
to steadily fall even though it will remain above action stage.

After this, low pressure will again track to the north and bring
more much above normal temperatures and a period of rain. Although
the previous system melted a lot of the snow pack, there is still a
significant snow pack in place across the Tug Hill and the Western
Adirondacks. Run-off from snow melt will combine with rain from this
system to cause the Black River and its tributaries to rise again
late this week. The Boonville and Watertown forecast points are of
greatest concern, where there is a potential for flooding starts
late Wednesday night through Friday. Based on this, have issued a
Flood Watch for Lewis and Jefferson counties, with river flooding
the primary concern.

&&

.EQUIPMENT...
The KBUF radar is down due to equipment issues and will remain so
through at least late today and quite possibly through the end
of the week...depending upon how quickly replacement parts arrive
and how well repair efforts go.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...Wind Advisory from 4 PM this afternoon to 7 AM EST Thursday
     for NYZ001>003-010>012-019-085.
     Flood Watch from 7 PM EST this evening through Friday morning
     for NYZ007-008.
     Wind Advisory from 7 PM this evening to 1 PM EST Thursday for
     NYZ004>008-013-014-020-021.
MARINE...Small Craft Advisory from 11 AM this morning to 6 PM EST this
         evening for LEZ040-041.
         Gale Warning from 6 PM this evening to 4 AM EST Thursday
         for LEZ040-041.
         Small Craft Advisory until 6 AM EST Thursday for LEZ020.
         Small Craft Advisory from 1 PM this afternoon to 6 AM
         EST Thursday for LOZ030.
         Gale Warning from 7 PM this evening to 10 AM EST Thursday
         for LOZ042>045-062>065.

&&

$$

SYNOPSIS...WCH
NEAR TERM...RSH/WCH
SHORT TERM...HITCHCOCK
LONG TERM...HITCHCOCK/SW
AVIATION...RSH/WCH
MARINE...WCH
HYDROLOGY...APFFEL
EQUIPMENT...JJR



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