Forecast Discussion

Forecast Discussion for BUF NWS Office
000
FXUS61 KBUF 241044
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
644 AM EDT Fri May 24 2019

.SYNOPSIS...
High pressure will pass over the Lower Great Lakes resulting in
mainly dry weather today. Conditions will then deteriorate late
tonight through Saturday night due to a pair of frontal systems
which will push through the region. High pressure will then ridge
southward from Canada and into the Great Lakes providing mainly dry
weather for Sunday and Monday.

&&

.NEAR TERM /THROUGH TONIGHT/...
High pressure over the Upper Great Lakes will gradually build across
the region and provide mainly dry weather for today. Moisture
will circulate around stacked low pressure centered near Maine.
This will support some morning cloud cover, and some light
showers east of Lake Ontario. Breaks of sunshine will increase
from west to east as this system exits off the Maine coast this
afternoon. Today will be cooler than yesterday with high
temperatures in the mid 60s for most areas.

High pressure across the region this evening will maintain dry
weather well into tonight. However the mid-level ridge axis will
move to our east late tonight with a warm front approaching the area
from the west. Some showers and thunderstorms will develop along a
mid-level thermal gradient and move into far Western New York
late tonight. Areal coverage should be scattered in nature
through daybreak. Low temperatures will be near or shortly
after midnight with radiational cooling hindered by mid and high
level cloud cover which will be moving into the region from the
southwest.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
A strong anticyclone over the Southeast will be advancing Gulf of
Mexico moisture northward through the Mississippi Valley to close
out this week. On Saturday this moisture will reach our region,
producing a noticeable rise in humidity, while also fueling showers
and thunderstorms through the day and evening.

A warm front will nose eastward into Western New York Saturday
morning, with elevated instability of 250 - 500 J/KG supporting some
convective rain showers. The isentropic gradient will lie across
Lake Erie, and towards the thruway early Saturday morning, and along
this boundary is also where condensation pressure deficits will fall
to support rain showers. Will start the day for the Niagara Frontier
with categorical PoPs...and with the LLJ still well to our west any
thunderstorm should be just a garden variety. This activity will
likely weaken some through the morning hours as it pushes eastward
across Lake Ontario and towards the North Country.

The falling rain, plus a southerly stream of moisture will raise
dewpoints into the mid 60s across WNY, and upper 50s east of Lake
Ontario. By May standards...this will be a bit humid. This increase
in moisture as well as daytime highs in the 70s to near 80F will
increase SB CAPE through the day to 1000 to 2000 J/KG.

Precipitation coverage may be sparse around midday, and not until
much later in the afternoon and into the evening hours will showers
and thunderstorms return. A shortwave will ripple eastward across
southern Ontario Saturday afternoon helping to produce a line of
showers and thunderstorms. Aided by a 45 to 55 knot LLJ, and 0-6 km
bulk shear values of 50 to 55 knots storms blossoming within this
unstable environment could become strong to severe, with damaging
winds the likely threat. CAPE profiles aloft on point soundings look
to be more tall and skinny...which would not favor hail formation.
If greater CAPE develops, hail could be possible with taller cells.

With confidence growing in the low level wind profiles, will place
gusty winds into the grids for these thunderstorms across portions
of WNY. To the east while thunderstorms are still likely, the
instability will be weaker...and for now will not place gusty winds
into the forecast. At this time the period for severe thunderstorms
will likely be in the late afternoon and through the evening hours.

Sunday a weak frontal boundary will drop southward across the
region. We will still be on the humid side to start the day and a
few showers or thunderstorms remain possible through the afternoon
as we`ll remain unstable. This precipitation will end through Sunday
early evening as moisture depletes as surface high pressure over
Canada funnels drier air southward. Skies will clear through the
night with overnight temperatures dropping back into the lower 50s.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
Increased ridging will begin on Monday over the eastern third of the
country. This will provide rainfree conditions for Monday, with
comfortable levels of humidity as surface high pressure to the north
pushes drier air southward.

As the ridge strengthens over the southeast U.S., a similar scenario
to this weeks weather will take shape. The ridge over the southeast
U.S. will cause waves of low pressure to trek northeast out of
western half of the country where a trough will be in place. Waves
of low pressure will increase the chance for showers and
thunderstorms from Tuesday through Thursday across western and north
central NY.

Ahead of these areas of low pressure warming temperatures on Tuesday
and Wednesday will bring highs across the area to the upper 70s to
mid 80s. A passing cold front late Wednesday/early Thursday will
bring slightly below normal temperates to the area with highs in the
mid to upper 60s.

&&

.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
A closed low will settle across Maine this morning which will
increase moisture and result in cloud cover and lower cigs
through the morning hours. This will result in areas of MVFR
clouds, especially east of Lake Ontario but also south of Lake
Ontario where these clouds will be more patchy in nature.

Cloud bases will lift late this morning, and eventually scatter
out this afternoon and evening with widespread VFR flight
conditions. A warm front will approach from the southwest late
tonight. This will result in an area of low to mid level clouds
and possibly a shower or thunderstorm west of Rochester near
daybreak Saturday.

Outlook...
Saturday...VFR/MVFR with showers likely and a chance of
thunderstorms. Some storms could produce gusty winds.
Sunday...VFR/MVFR with a chance of showers and thunderstorms.
Monday...VFR.
Tuesday...Mainly VFR with a chance of showers and thunderstorms.

&&

.MARINE...
Winds have picked up behind a cold front, which will support
small craft advisory conditions this morning, particularly along
the southeastern shores of Lake Ontario.

Winds will then subside this afternoon as high pressure will
push east from the Upper Great Lakes. Generally light winds and
negligible waves can then be anticipated tonight and Saturday.

&&

.TIDES/COASTAL FLOODING...
A cold front has moved across the area with westerly winds
producing higher waves, especially across the eastern half of
Lake Ontario. This combined with very high lake levels will
result in flooding along the shorelines of Wayne...Northern
Cayuga...and Oswego Counties. Winds and waves will diminish by
this afternoon which will lower the flooding concerns.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...Lakeshore Flood Warning until 11 AM EDT this morning for
     NYZ004>006.
MARINE...Small Craft Advisory until 11 AM EDT this morning for LOZ043-
         044.

&&

$$

SYNOPSIS...Apffel
NEAR TERM...Apffel
SHORT TERM...Thomas
LONG TERM...SW/Thomas
AVIATION...Apffel/RSH
MARINE...Apffel/RSH
TIDES/COASTAL FLOODING...JJR/Apffel

NWS BUF Office Area Forecast Discussion