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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KBUF 180434
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
1234 AM EDT Thu Apr 18 2024

.SYNOPSIS...
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Weak high pressure will provide much improved weather across the
western counties on Thursday...but showers will persist for areas
east of Lake Ontario. A wave of low pressure riding up along a slow
moving frontal boundary will then guarantee another unpleasant day
across all of the region for Friday in the form of widespread
showers...if not several hours of steady rain. While fair dry
weather will be featured for the upcoming weekend...some nuisance
showers will be possible Saturday afternoon.
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&&

.NEAR TERM /UNTIL 6 PM THURSDAY EVENING/...
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A stacked storm system in the vcnty of the SOO will push a
weakening sfc occlusion across the western counties overnight.
This will support some light rain for most areas with rainfall
between midnight and daybreak generally under a tenth of an
inch. Amounts as high as a quarter will be possible east of Lake
Ontario.

On Thursday...the frontal boundary will make its way across the
North country. This will be enough to generate some more showers
for that area...while weak high pressure should allow for mainly dry
weather over the western counties. Unfortunately...there should be
enough low level moisture over the western counties to minimize the
amount of sunshine received.
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&&

.SHORT TERM /6 PM THURSDAY EVENING THROUGH SATURDAY NIGHT/...
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A weakening mid-level ridge across the Eastern Seaboard
Thursday night will give way to broad troughing overhead of the
Great Lakes by Friday where it will remain overhead into the
weekend. Within this troughing pattern a few shortwave troughs
will round its base creating on and off active weather.

Thursday night, an occluded front sprawled across the eastern Lake
Ontario region will continue to exit east, supporting lingering
light rain showers. In the wake of the frontal passage, a transient
ridge will slide east across the region providing a short period of
dry weather.

A shortwave will begin to round the base of the trough Friday and
Friday night, supporting a the low pressure system over northern
Ontario to strengthen and gradually move into central Quebec by
Friday night. This will introduce an associated strong cold front to
sweep across the region from west to east, supporting steady rain to
fall. Rainfall amounts will average between a tenth to a quarter of
an inch. By Friday evening, rain showers will be exiting the North
Country, while a dry air mass fills with the approaching surface
ridge.

The aforementioned potent shortwave will then round the base of mid-
level trough and cross the area Saturday. This will support a
secondary cold front to pass across the region starting Saturday
morning with an uptick in rain shower activity Saturday afternoon.
Broad surface high pressure over the Central Plains will begin to
work its way east Saturday night.
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&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
High pressure centered over the Plains States at the start of this
period will ridge eastward across our area through Monday...then
will drift east across New England Monday night. This will help to
keep any passing weak northern stream systems confined to Ontario
and Quebec...thereby resulting in fair dry weather for our region.
With broad/flat troughing aloft on Sunday giving way to more of a
zonal flow during Monday...initially below-normal highs in the mid
40s to lower 50s Sunday will be followed by a return to near-normal
readings in the mid 50s to lower 60s on Monday.

While the medium range guidance packages continue to differ in some
of the details...there remains general agreement that a low-
amplitude mid-level trough and its associated surface reflection
will push east and across our region between Tuesday and Wednesday.
This system will bring our next general chance of showers...with
slightly above normal temps (upper 50s-mid 60s) out ahead of it on
Tuesday giving way to slightly below normal readings (generally low-
mid 50s) following its passage on Wednesday.

&&

.AVIATION /06Z THURSDAY THROUGH MONDAY/...
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Cigs will deteriorate to MVFR levels across most of the region
overnight...as light rain will be in place from a passing sfc
occlusion. IFR cigs will be likely northeast of both lakes...and
possibly across the Srn Tier...especially after 08z.

Showers should persist east of Lake Ontario on Thursday...while MVFR
cigs should dominate the skies.

Outlook...

Thursday night...Mainly VFR. A chance of showers.
Friday and Saturday...MVFR/VFR with a chance of showers.
Sunday and Monday...Mainly VFR.
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&&

.MARINE...
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Moderate breezes will be found throughout much of the Lower Great
Lakes during the rest of the overnight...as a weakening sfc
occlusion will move through. Will thus drop all headlines on Lake
Ontario.

In the wake of the aforementioned frontal boundary...southwest winds
on Thursday will freshen on Lake Erie. While this will no doubtable
increase the likelihood for choppy conditions...there is only a
minimal chance that a small craft advisory will be needed.
Otherwise...gentle to moderate breezes will be found on Lake
Ontario.

A weak sfc pressure gradient in advance of the next wavy frontal
boundary Thursday night will only support gentle to moderate breezes
and negligible wave action.

Winds will significantly freshen on both lakes on Friday though when
there will likely be the need for small craft advisories.
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&&

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

$$

SYNOPSIS...RSH
NEAR TERM...RSH
SHORT TERM...EAJ
LONG TERM...JJR
AVIATION...RSH
MARINE...RSH