Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 230619

Area Forecast Discussion
National Weather Service Buffalo NY
219 AM EDT Tue May 23 2017

A weak ridge of high pressure will bring dry weather today through
most of Wednesday with temperatures above normal. Low pressure will
then bring more rain to the region Wednesday night and Thursday with
temperatures closer to normal.


A weak ridge of high pressure surface and aloft will continue to
shift over the Lower Great Lakes this morning. Subsidence and drying
associated with this high will continue to support mainly clear
skies. The clear skies and a fairly cool airmass will allow for some
radiational cooling with low temperatures in the upper 40s to around
50 on the lake plains, with low to mid 40s in the cooler sections of
the interior Southern Tier and Lewis County.

The weak surface ridge stretched from the upper Ohio Valley to New
England will slowly shift northeast. Warm air advection and a weak
mid level shortwave will move northeast across southern Ontario with
little direct impact on our area although it will bring scattered
showers and thunderstorms north of the Canadian border. While we
will remain dry today, the shortwave will bring some increase in
moisture and cloud cover, with both mid level clouds and diurnal
cumulus developing across the region. Stable lake shadows will allow
more sunshine northeast of Lakes Erie and Ontario. Temperatures will
rebound, with highs in the lower to mid 70s away from lake
influences. Weak synoptic scale flow and strong differential heating
will allow local lake breezes to develop with winds becoming onshore
along all the shorelines in the afternoon, keeping temperatures
cooler within a few miles of the lakes.


Bubble of high pressure becoming centered across New England will
maintain dry weather across the area through the first half of
Wednesday. Overnight lows Tuesday night will fall back into the
upper 40s to lower 50s.

High pressure will exit the region Wednesday as a deepening surface
low slowly tracks into the Ohio Valley. Model tracks differ
slightly, but most of the guidance eventually tracks this low across
Ohio Wednesday night and across Lake Erie on Thursday. Increasing
moisture transport and lift on the front side of the approaching low
will eventually allow precipiation to blossom across the area. Onset
time may be slowed a bit from continuity based on slower track of
approaching surface low. Warm air advection and slower timing of
precipitation onset should allow high temperatures Wednesday to
reach the lower to mid 70s.

Does look like there will be at least a solid 6 to 12 hour period of
fairly steady rain starting late Wednesday in the far west and
filling in across the rest of the area through Thursday. The steady
rain should taper to more showery weather by Thursday night as the
surface low starts to shift east of the area.


Our region will be under the influence of a progressive...northern
branch of a split flow during this period. While this will allow for
fairly frequent shower activity...a closed off GOMEX will keep
rainfall amounts to a minimum. This pattern will also keep
temperatures from straying too far from normal...but on average...
they will tend to run a few degrees above typical late May values.
Breaking this down on a day to day basis...

A stacked storm system over eastern New York Friday morning will
exit across New England during the afternoon and evening. This will
keep some showers in place over our region...particularly east of
Lake Ontario where pops will be raised to likely. Temperatures on
Friday will climb into the 60s.

Ridging will build across the Lower Great Lakes late Friday night
and Saturday. While the models are not convinced that dry weather
will prevail during this time fairly confident that the
aforementioned ridging and lack of mid level moisture will translate
into fair dry conditions. This should also help Saturday afternoon
temperatures climb into the 70s across most of the western counties.

As the ridge pushes east of our region Sunday and Monday...the next
longwave trough will dig across the Upper portions of the
Mississippi Valley and Great lakes region. This will result in
deteriorating conditions...particularly late Sunday into Monday. In
other it stands now we should be able to get through most
of Sunday before the skies `open` again. Given the inconsistencies
between the medium range ensembles though...confidence is lower than


A weak ridge of high pressure will build over the Lower Great Lakes
region through today and tonight with VFR. Weak warm advection and
diurnal cumulus will bring some increase in cloud cover as a
disturbance moves north of Lake Ontario but CIGS will remain VFR
with light southwest winds. The high pressure will continue to bring
VFR and fair weather through tonight.


Wednesday night...VFR/MVFR with a chance of showers.
Thursday...VFR/MVFR with showers likely.
Friday...VFR/MVFR with a chance of showers.
Saturday...Mainly VFR.


Weak high pressure will build over the Lower Great Lakes today
through Wednesday, providing light winds and light wave action
through the middle of the week. A storm system will pass over our
region Wednesday night through Friday but winds and waves will
remain below advisory levels.





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