Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 172310
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
710 PM EDT Mon Jul 17 2017

.SYNOPSIS...
Weak high pressure centered over the Lower Great Lakes will support
fair dry weather across our region through at least Wednesday
morning. The first of a pair of cold fronts will then move through
late Wednesday afternoon and night to generate some showers and
thunderstorms. Temperatures the next several days will average close
to...or just a bit above normal.

&&

.NEAR TERM /THROUGH TUESDAY/...
A weak area of high pressure over Michigan this evening will shift
east overnight with mainly clear skies. BUFKIT profiles suggest this
clearing will allow a nocturnal inversion to develop overnight with
leftover low level moisture supporting the potential of patchy fog
across the area. As one would expect...the most widespread fog will
be found in the deeper river valleys of the Southern Tier. Low temps
are forecast to settle into the mid to upper 50s in the western
Southern Tier to the lower 60s in the Lake Plains and North Country.

The weak surface high will center over Lake Erie Tuesday with
surface and mid-level ridging extending across all of western and
north-central NY. After morning fog dissipates, expect dry weather
with mainly sunny skies through the day. Diurnal cumulus should
again build inland of lake breezes but the subsidence inversion will
prevent any showers. Temperatures aloft will edge warmer pushing
above 15C at 850mb. Mixing will allow this to support daytime highs
in the upper 70s to low 80s with relatively comfortable humidity
levels.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY NIGHT/...
On Tuesday night a weak surface high will ridge into the region,
providing dry weather and clearing skies. This will result in good
radiational cooling conditions, with forecast lows ranging from the
lower 50s to lower 60s which is slightly below consensus temperature
guidance. There also will likely be fog in the typically cooler
Southern Tier valleys.

Slightly warmer and more moist air will build into the region on
Wednesday. Meanwhile, a weak mid-level wave is forecast to move
across the area late Wednesday afternoon and evening. Expect that
the weak surface ridge will largely keep our area dry Wednesday with
just a slight chance for afternoon showers or storms. There is a
chance that weakening showers and thunderstorms which develop along
this wave will make it into the region Wednesday night. Highs
Wednesday will warm to the lower to mid 80s. More extensive cloud
cover will hinder radiational cooling Wednesday night with lows in
the 60s.

12Z guidance has backed off considerably on a wave which was
forecast to move across the area on Thursday. There still will be a
weak frontal boundary extending from Michigan to Western New York
which may serve as a focus for some convection if even a subtle wave
forms. So will maintain chance PoPs near this boundary, despite the
lower QPF with the 12Z guidance. By Thursday night, this boundary
should push southward, with diminishing chances for showers and
thunderstorms later in the night. High pressure and a notably drier
airmass will gradually build across the Lower Great Lakes late
Thursday night.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
The upper level pattern shows a general zonal flow through the first
half of the extended period, becoming troughy over the Great Lakes
region by Sunday into Monday. Friday looks like it will remain
mostly dry as a transient area of high pressure moves into the area
in the wake of the trough/frontal passage Thursday night. This
frontal boundary will remain stalled south of the region on
Saturday. This will result in fairly seasonable temperatures and
mainly dry weather for the first part of the weekend. By Sunday and
into Monday, the aforementioned troughing swings through with the
weather becoming more unsettled as it helps to push the frontal
boundary northward across the region. This will bring the
return of the warm, moist and unstable airmass across the region
as well as more widespread thunderstorm chances for the second
half of the weekend and into early next week.

&&

.AVIATION /23Z MONDAY THROUGH SATURDAY/...
High pressure centered over the Lower Great Lakes will provide the
region with VFR conditions through this evening. While mainly clear
skies will be found across the region overnight...patchy fog will
develop in some areas to reduce vsbys to MVFR levels. The highest
chance for fog will be across the Southern Tier where vsbys will
likely drop to LIFR levels at sites like KJHW and KOLE.

The fog will lift into an hour or so of stratus to start the day
Tuesday...then VFR conditions will return to all of western and
north central New York for the majority of the day.

Outlook...
Tuesday night and Wednesday...Mainly VFR.
Thursday...VFR/MVFR. A chance of showers and thunderstorms with
possible MVFR.
Friday...VFR.
Saturday...a chance of showers and thunderstorms with possible
associated MVFR.

&&

.MARINE...
Winds will remain relatively light at less than 10 knots with light
wave action through this week as the pressure gradient remains weak
across the eastern Great Lakes. A cold front will cross the eastern
Great Lakes Wednesday night and Thursday with more chances for
showers and thunderstorms.

&&

.EQUIPMENT...
The KBUF WSR-88D has experienced a major equipment failure. A
national support team arrived last night and has been working on
the issue all day. There is the potential that the radar could
be operational sooner than anticipated.

&&

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

&&

$$

SYNOPSIS...RSH
NEAR TERM...RSH/SMITH
SHORT TERM...APFFEL
LONG TERM...CHURCH/TMA
AVIATION...RSH
MARINE...SMITH
EQUIPMENT...HITCHCOCK/RSH



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