Area Forecast Discussion
Issued by NWS Buffalo, NY

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS61 KBUF 201449
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
1049 AM EDT Fri Apr 20 2018

.SYNOPSIS...
Cool but largely dry weather will prevail this afternoon as low
pressure exits across the Canadian Maritimes...with just a few
flurries possible across the eastern Finger Lakes and North Country.
Expansive high pressure will then build across the region this
weekend...ushering in a welcome period of fair dry weather and
day to day warming that will last through early next week...when
temperatures will finally climb back to much more typical springtime
levels.

&&

.NEAR TERM /THROUGH SATURDAY/...
Nearly vertically stacked low pressure over the Canadian Maritimes
will continue to drift eastward and away from our region today...
while expansive high pressure and drier air slowly ridges eastward
from the Upper Mississippi Valley. A lingering northwesterly upslope
flow of colder air and leftover low level moisture in the wake of
the low will help to maintain a fair amount of stratocumulus from
the interior portions of the Southern Tier northeastward across the
Finger Lakes and North Country...though at the same time the moisture
will be too shallow to support much more than a few passing flurries
or light snow showers across the far eastern Finger Lakes and North
Country...none of which should produce any noteworthy accumulation.
Elsewhere there will be a bit more in the way of sunshine...with
daytime highs ranging from the mid to upper 30s east of Lake Ontario
to the upper 30s and lower 40s across the remainder of the region.

Tonight the sprawling surface high will continue to build eastward
from the Upper Great Lakes while helping to scour out any leftover
low level moisture from west to east...thereby leading to clearing
skies and tranquil conditions. In tandem with lightening winds and
our cold dry airmass...this will set the stage for a cold night with
lows ranging from the lower to mid 20s in the normally colder interior
portions of the Southern Tier and North Country...to around 30 right
along the lakeshores.

On Saturday the core of the large surface ridge will build directly
across our area...with attendant subsidence and plentiful dry air
promoting dry weather along with mostly sunny skies...with a passing
upper level jet streak merely bringing a period of cirrus-level
cloudiness to portions of the western Southern Tier. Meanwhile the
strong April sun will help to modify our resident airmass...thereby
allowing daytime highs to recover into the mid to upper 40s across
the higher terrain and in areas of lake influences to the lower 50s
elsewhere. This will merely be the beginning of a steady day to day
warming trend that will last through early next week and will help
to finally bring temperatures back up to much more typical springtime
levels...the details of which are discussed further in the short term
section below.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
Saturday night 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 on Sunday. The weak northerly
flow will prevent any bonafide warm advection, but steady
airmass modification will continue to allow for good day to
day warming. Sunday`s highs will be into the mid 50s in most
locations...though the light northerly flow 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 /15Z FRIDAY THROUGH TUESDAY/...
Low pressure over the Canadian Maritimes will continue to drift
eastward today...while large high pressure and drier air slowly
ridges eastward from the Upper Mississippi Valley. A lingering
northwesterly upslope flow of colder air behind the departing low
will help to maintain a fair amount of VFR/MVFR strato-cumulus from
the interior portions of the Southern Tier northeastward across the
Finger Lakes and North Country today...while the remainder of the
region experiences VFR conditions under more of a mix of sun and
clouds.

Tonight the sprawling surface high will continue to build eastward
from the Upper Great Lakes...bringing clearing skies and widespread
VFR conditions. On Saturday VFR conditions will continue as the
high builds directly over our region.

Outlook...
Saturday night through Tuesday...VFR.

&&

.MARINE...
A lingering moderately brisk northwesterly flow of cold air will
maintain advisory-worthy winds and/or waves along the south shore
of Lake Ontario into early this afternoon...with conditions then
improving from west to east this afternoon and early this evening
as high pressure builds into the region along with diminishing
winds.

After that...an extended period of tranquil conditions is expected
this weekend and early next week as high pressure first builds
directly across the Lower Great Lakes...then slowly drifts off to
the east.

&&

.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.

&&

$$

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



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.