Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 201049
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
649 AM EDT Fri Apr 20 2018

.SYNOPSIS...
Expect a cool day with a mix of clouds, sun, and a few passing
flurries today as a low pressure system over New England slowly
exits into the Canadian maritimes. High pressure will build across
the region this weekend into early next week finally bringing drier
weather and moderating temperatures.

&&

.NEAR TERM /THROUGH TONIGHT/...
A large upper-level trough over New England will take its exit into
the Canadian maritimes through tonight while ridging over the upper
Great Lakes starts to build into the region.

Early this morning, most snow showers have dissipated leaving a mix
of low clouds and some breaks of clear sky. Today, expect lingering
low level moisture with upslope flow to maintain a stratocumulus
cloud deck across much of the region. Cannot rule out a few light
snow showers or flurries out of this cloud deck, but drier air and
increasing subsidence into the region will keep these minimal with
no further snow accumulation expected. Temperatures today will
remain on the cool side with the lingering northerly flow across the
region and mainly cloudy conditions. Highs will top out in the upper
30s over the high terrain and the low 40s along the lake plains.

Tonight, high pressure will continue to build across the region.
This will be the start of a long stretch of dry and tranquil weather
across the region into early next week. Lows tonight will be on the
chilly side though, with clearing skies allowing temperatures to hit
the mid 20s inland and around 30 in the lake plains.

&&

.SHORT TERM /SATURDAY THROUGH MONDAY/...
Saturday and Sunday surface high pressure will drift slowly from the
central Great Lakes to the eastern Great Lakes. Meanwhile a deep
trough over the Canadian Maritimes will drift very slowly east,
still maintaining weak northerly flow across our region. The high
pressure will bring dry weather over the weekend with abundant
sunshine both days. The weak northerly flow will prevent any
bonafide warm advection, but steady airmass modification will allow
for good day to day warming. Expect highs Saturday of around 50 at
lower elevations in Western NY, and mid to upper 40s for higher
terrain and east of Lake Ontario. By Sunday highs will be into the
mid 50s in most locations. Light northerly flow both Saturday and
Sunday will keep the south shores of Lakes Erie and Ontario cooler.

By Monday the center of the surface high will drift off the southern
New England coast. Ridging surface and aloft will keep the stretch
of dry weather going, with just a modest increase in high clouds to
the north of a cutoff low over the Tennessee Valley. Increasing
boundary layer warm advection will allow highs to reach the low to
mid 60s in most areas. Synoptic scale flow will likely remain weak
enough to allow lake breezes to form, keeping the lakeshores
cooler.

&&

.LONG TERM /MONDAY NIGHT THROUGH THURSDAY/...
Monday night and Tuesday a closed low over the Tennessee Valley will
drift slowly northward into the Ohio Valley. This will bring a
gradual increase in mid/high clouds as moisture spreads northward
ahead of the system. Ongoing warm advection will allow for a
continued upward trend in temperatures, with highs likely well into
the 60s on Tuesday as long as cloud cover does not become too thick.
Any showers should stay south of the NY/PA line through late Tuesday
afternoon.

Tuesday night through Thursday medium range model guidance begins to
diverge some in the track and timing of synoptic scale systems. The
GFS takes the Ohio Valley low slowly northward towards our region,
phasing it with another northern stream trough digging into the
western Great Lakes. This would bring several days of showers and
clouds from Tuesday night through Thursday. The ECMWF keeps these
two systems more separate, with the closed low moving northeast
along the eastern seaboard, as the second northern stream trough
acts more as a kicker than phasing. The ECMWF would produce a few
light showers later Tuesday night through Wednesday evening before
dry weather returns Thursday. Given the spread in model guidance,
kept POPS in the chance range through the period, peaking on
Wednesday.

Temperatures will pull back some behind this system by late next
week, but 850mb temps are still above 0C in its wake. This will
prevent any return to winter-like temperatures, with highs in the
50s still probable late next week behind the system.

&&

.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
Mainly VFR conditions will continue early this morning, with
localized MVFR away from the TAF sites in snow showers over the
higher terrain.

Snow shower activity will continue to diminish Friday, but low-level
moisture and upslope/lake enhanced flow will maintain a MVFR/VFR
stratocumulus deck across much of the region through the day.

Outlook...

Saturday...Mainly VFR.
Sunday through Tuesday...VFR.

&&

.MARINE...
Small craft conditions have diminished on Lake Erie, but will linger
on Lake Ontario through much of the day before finally ending this
afternoon and evening as high pressure builds toward the lower Great
Lakes.

A period of more tranquil conditions will come this weekend into
early next week as high pressure moves over the lower Great Lakes.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...None.
MARINE...Small Craft Advisory until 8 PM EDT this evening for LOZ043-
         044.
         Small Craft Advisory until 2 PM EDT this afternoon for
         LOZ042.
         Small Craft Advisory until 5 PM EDT this afternoon for
         LOZ045.

&&

$$

SYNOPSIS...Church
NEAR TERM...Church
SHORT TERM...Hitchcock
LONG TERM...Hitchcock
AVIATION...Church
MARINE...Church



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