Forecast Discussion

Forecast Discussion for BUF NWS Office
000
FXUS61 KBUF 160901
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
501 AM EDT Mon Jul 16 2018

.SYNOPSIS...
Heat and humidity will peak across the region today, with a few
thunderstorms blossoming this afternoon across inland Western New
York, and then becoming more widespread this evening and overnight
ahead of a cold front. Showers and drenching thunderstorms will
taper off from west to east early Tuesday. Behind the cold front a
refreshing airmass will settle upon the Great Lakes region, with
comfortable levels of humidity and summer`s warmth through the end
of the work week.

&&

.NEAR TERM /THROUGH TONIGHT/...
It will be a quiet start to the morning, albeit quite warm with many
locations starting the day in the mid 60s to lower 70s...with
dewpoints not that much lower. This low dewpoint depression, along
with light winds and mainly clear skies has allowed for some patches
of fog to form, both across the So. Tier and to the SE and E of Lake
Ontario. This fog will end shortly after sunrise...and much of the
region will remain mostly sunny through the morning hours.

This sunshine, combined with 850 hPa temperatures of +18 to +19C
will again bring mid 80s to lower 90F temperatures to our region.
These values, a degree or two warmer than yesterday, combined with a
slight increase in the dewpoints will bring apparent temperatures
into the 90s, with mid to upper 90s across the Lake Plain, Genesee
Valley and northern Finger Lakes region. A heat advisory, including
now northern Erie and Genesee counties, will continue today.

As has been the case the past day or two, winds through the lower
atmosphere will remain weak. Even though our SB CAPE values will be
climbing to 1000 to 2000 J/KG, and moisture will be
plentiful...thunderstorm development will be slow to go at
first...with most storms forming on lake breeze circulations across
inland WNY during the afternoon hours. These storms could bring a
heavy downpour as PWAT values are near 1.75 to 2.00 inches.

A shortwave to the north of Minnesota this morning will advance
eastward through the Great Lakes region today and tonight,
displacing the upper level ridge axis eastward. Aloft heights will
begin to fall, and these falling heights combined with a nearing
cold front will enhance synoptic lift such that thunderstorms will
begin to increase in numbers late this afternoon and evening.

Ahead of the shortwave a line of thunderstorms will likely form
overnight, crossing through much of the region by daybreak tomorrow.
Wind fields will remain modest at best, with a wind field of 25 to
30 knots between 850 and 700 hPa supporting these storms. Any
wind damage may actually come from a collapsing core within a
thunderstorm, with widespread damaging winds not likely due to
the rather weak synoptic winds aloft. SPC will maintain the
marginal risk for severe storms through tonight, with damaging
winds possible.

These storms will continue to also have potential for heavy
rain. Due to the convective nature of these storms, QPF will
widely range, but a basin average of half to one inch of rain is
likely within such storms. MBE vectors less than 10 knots, and
a warm cloud layer exceeding 12K feet, along with PWATS nearing
2.0 inches will make for efficient heavy rain makers. Will
continue to mention the risk for heavy rain within the HWO
product.

The cold front will reach far WNY towards daybreak tomorrow. This
will mean one more night with warm temperatures and muggy levels of
humidity. Overnight lows will drop back into the upper 60s to lower
70s.

&&

.SHORT TERM /TUESDAY THROUGH THURSDAY NIGHT/...
A surface cold front will bring some much welcomed relief from our
recent stint of heat and humidity Tuesday. The front will be near
the Genesee Valley by daybreak and clearing east across central NY
by midday. Showers and possibly some thunderstorms will be most
prevalent along the front across CNY during the morning with all
precip ending by midday. An incoming dry airmass under a breezy
northwest flow behind the front will help clear skies west to east
through midday as well as quickly lower dewpoints to much more
comfortable levels in the 50s. 850mb temps falling to around +12C
will support high temps closer to normal levels in the upper 70s to
low 80s Tuesday.

The broad Canadian-sourced high pressure will continue to provide a
cooler/drier and more comfortable airmass across western and north-
central New York Wednesday and Thursday. This high along with a mid-
level ridge pivoting across the Great Lakes will support dry weather
through the end of the work week. Daytime highs in the mid to upper
70s Wednesday will climb back into the low to mid 80s through
Thursday. The drier airmass will also mean cooler nights dipping
into the 50s across most locations. Meanwhile humidity levels will
be very comfortable thanks to surface dewpoints ranging in the lower
to mid 50s.

&&

.LONG TERM /FRIDAY THROUGH SUNDAY/...
The center of the surface high will shift off the New England coast
Friday with surface ridging extending west across the eastern Great
Lakes. Expect that the ridging will provide for another dry day
Friday ahead of our next storm system working into the upper Great
Lakes. A general southerly flow on the back side of the surface high
will advect increasing amounts of warmth and moisture into our
region. High temps Friday will return above normal with readings
mainly in the mid to upper 80s while dewpoints make a run for 60F
returning a more humid feel to the air.

Multi-model 00z consensus then shifts a surface low north/northeast
across the upper Great Lakes into Ontario Province over the weekend.
An associated occluded front looks to make a slow push toward or
across WNY over the weekend with the consensus showing a chance for
showers/storms at least across WNY Saturday. By Sunday all of the
forecast area will see a chance for precip from what models are
showing as a coastal low with tropical origins lifting north ahead
of the slow/stalled front. Heat and humidity will linger Saturday.
Sunday will be more tricky with cooling possible if the front were
to push east of the forecast area.

&&

.AVIATION /09Z MONDAY THROUGH FRIDAY/...
For the 06Z TAFS VFR flight conditions are found. Mainly clear
skies, light winds and low dewpoint depressions will encourage fog
formation with some fog across the inland So. Tier, and also in
spots east of Lake Ontario. Fog may remain just to the east of the
KJHW terminal, while some reduction in visibility is possible across
KART before sunrise.

For today the morning hours will remain quiet, but within an
unstable, moist atmosphere thunderstorms are expected to blossom
this afternoon. These storms will primarily be heavy rain makers,
with flight conditions briefly reduced to IFR/MVFR. Activity is
expected first along the lake Erie lake breeze circulation across
WNY, and then ahead of a cold front additional storms will blossom,
with a line of storms passing from west to east across the region
tonight. Again while storms are likely, it will be tough to time the
lowering flight conditions...so will have primarily VFR in the TAFS.

Winds will veer to west to northwest late tonight across the western
TAF sites.

Outlook...

Tuesday...VFR/MVFR in showers and thunderstorms.
Wednesday through Friday...VFR.

&&

.MARINE...
Light winds will continue across the lakes tonight. A building ridge
today will maintain waves less than 2 feet on the lakes. Storms are
expected to blossom this afternoon and overnight...with locally
higher winds and waves possible.

A cold front will pass across the Eastern Great Lakes region late
tonight and early Tuesday, with west to northwest winds freshening
Tuesday and Tuesday night. This may bring wave heights and wind
speeds to advisory levels, especially on Lake Ontario.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...Heat Advisory from noon today to 8 PM EDT this evening for
     NYZ001>006-010-011-013-014.
MARINE...None.

&&

$$

SYNOPSIS...Thomas
NEAR TERM...Thomas
SHORT TERM...Smith
LONG TERM...Smith
AVIATION...Thomas
MARINE...Thomas

NWS BUF Office Area Forecast Discussion