Area Forecast Discussion
Issued by NWS Buffalo, NY

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688
FXUS61 KBUF 230530
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
130 AM EDT MON MAY 23 2016

.SYNOPSIS...
High pressure over the Upper Great Lakes will gradually push east
during the next several days. This will promote beautiful weather
for the first half of the work week as temperatures will climb to
above normal levels. For the latter portion of the week...it will
become summery with warm and somewhat humid conditions feeding an
increasing chance for showers and thunderstorms.

&&

.NEAR TERM /THROUGH TODAY/...
Radar imagery showing the last remaining scattered showers across
the Finger Lakes. These showers should weaken and dissipate just
prior to reaching our CWA based on recent radar trends. Otherwise a
patch of mid level clouds over the Finger Lakes will push west
across the Genesee Valley and tend to scatter out by daybreak. Lows
will drop into the mid 40s in the cooler Southern Tier valleys and
Tug Hill region, with lower 50s on the lake plains.

Monday will be an absolutely gorgeous day across our region. The
axis of the aforementioned surface high will make its way across
the Lower Great Lakes...with the associated subsidence and
continued mid level drying leading to sun filled skies. The trend
of higher temperatures will continue as well...as H85 temps in the
vicinity of 10c will easily support afternoon mercury readings in
the mid to upper 70s.

&&

.SHORT TERM /TONIGHT THROUGH WEDNESDAY NIGHT/...
Closed upper low will move from the Carolina coast on Monday
evening, to the Gulf of Maine on Tuesday evening, then on to the
coast of Nova Scotia on Wednesday.

As this upper level low moves away from the region and high pressure
builds across the area from the west, we can expect pleasant spring
weather with above normal daytime temperatures but still rather cool
nights for Monday and Tuesday, then closer to normal on Wednesday
night.

Temperatures will be above normal during the period with daytime
highs mainly in the 70s on Monday and Tuesday. The exception will be
the immediate lakeshores which will only reach the 60s. A north to
northwesterly gradient flow on Monday will help suppress the typical
southwest lake breeze at Buffalo and Watertown. On Tuesday there
will be light westerly gradient flow with typical afternoon lake
breezes expected. In general expect slightly greater diurnal
temperature ranges than consensus temperature guidance due to the
dry regime. Nighttime lows will be in the upper 40s to lower 50s
each night.

An upper level ridge will remain across the region resulting in a
summer-like pattern with a prolonged period of above normal
temperatures. As the upper ridge axis approaches the region during
midweek, so will the opportunity for late day and evening
convection. There will be an opportunity for late day through
evening thunderstorms on Wednesday and Wednesday night as a couple
ripples of vorticity move across the upper ridge, from southern
Ontario to the North Country and spreading into western NY during
Wednesday evening and night. 850MB temperatures of +12C on Wednesday
morning will present afternoon high temperatures in the mid 70s to
lower 80s, and continued warmth in the boundary layer and higher
dewpoints will result in overnight low temperatures in the mid 50s
to lower 60s.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
Thursday through Sunday will feature summer-like weather...complete
with increasing humidity and day to day chances for mainly afternoon
showers and thunderstorms.

The overall synoptic pattern will feature a ridge of high pressure
building over the eastern Unites States...while a shortwave trough
of low pressure cuts from the desert Southwest to the western Great
Lakes. The main ridge axis will lie across the SE states and back
towards the Central Great Lakes region. At 500 hPa heights will
slowly increase through the long term period...and at 850 hPa...air
temperatures will range from +14 to +17c through the period. Warmest
850 hPa temperatures will come Saturday...during the peak height of
the upper level ridge.

Subtle shortwaves moving through the ridge axis...combined with
increasing instability from building moisture and warmth will
contribute towards afternoon showers and thunderstorms. Both the 12Z
ECMWF and 12Z GFS bring a shortwave across the region
Thursday...which with increasing amounts of moisture will likely
bring showers and thunderstorms. Otherwise hard to pinpoint which
day may feature highest chances for convection...and thus will have
just chance PoPs through the daytime and early evening hours.
Greatest chances will be the inland lake breezes over the northern
Niagara Frontier and hilly region east of Lake Erie...and higher
terrain east of Lake Ontario.

The southerly flow will also build the humidity through this period
with uncomfortable levels reached by the end of the week. Dewpoints
will reach to around 60F to the lower 60s. Air temperatures will
likely increase a degree each day...as 500 hPa heights slowly
increase. Afternoon highs will reach into the upper 70s to lower
80s...with the Genesee Valley likely reaching the mid 80s by Friday
and Saturday. Sunday may be a degree or two cooler as the upper
level ridge starts to come down. There will not be much airflow
under the ridge...but a SW wind will likely develop each
day...keeping the City of Buffalo a few degrees cooler...with the
cooling extending out to near the airport. Along the immediate Lake
Ontario shoreline...and then the western Saint Lawrence Valley...air
temperature will be a few degrees cooler owing to the still cool
eastern Great Lakes.

Overnight lows will drop back into the lower 60s...and with a
similar airmass all four nights should have similar overnight
lows.

&&

.AVIATION /06Z MONDAY THROUGH FRIDAY/...
VFR conditions will prevail for the 06Z TAF cycle. The last of the
showers across the Finger Lakes will dissipate before daybreak with
an area of mid level clouds drifting west and scattering out. Some
lingering low level moisture will allow cumulus to develop by midday
across the higher terrain well inland from the lakes, with scattered
bases around 5k feet. The lake plains will remain SKC with stable
lake shadows pushing inland on northwest flow. Skies will be clear
tonight with high pressure surface and aloft.

Outlook...
Tuesday and Wednesday...VFR.
Thursday and Friday...Mainly VFR with a chance of showers and
thunderstorms.

&&

.MARINE...
High pressure over the Upper Great Lakes this evening will slowly
push east during the overnight. This will keep a weak surface
pressure gradient in place across Lakes Erie and Ontario...so
light winds will persist.

The axis of the surface high will make its way across the Lower
Great Lakes Monday and Tuesday. This will support continued light
winds and negligible waves.

While winds are not forecast to appreciably freshen as we make our
way into the second of the week...the environment will become
increasingly supportive for thunderstorms. This will especially be
the case for Thursday and Friday.

&&

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

&&

$$

SYNOPSIS...RSH
NEAR TERM...HITCHCOCK/RSH/TMA
SHORT TERM...WCH
LONG TERM...THOMAS
AVIATION...HITCHCOCK
MARINE...HITCHCOCK



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