Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 250811
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
411 AM EDT Mon Mar 25 2019

.SYNOPSIS...
A large area of high pressure centered over the Canadian prairies
this morning will gradually build to the east across the Great Lakes
region through Wednesday. This will supply our region with a
prolonged period of fair dry weather that will be highlighted by
significant warming during the middle of the week.

&&

.NEAR TERM /THROUGH TONIGHT/...
While a cold front has slipped well south of our forecast area...
leftover clouds to the north of the anabatic natured boundary are
still in the process of clearing. This north to south improvement
will continue through the initial daylight hours this morning...
after which time a fair amount of subsidence and a wealth of dry air
in advance of a large surface high will guarantee mainly clear skies
across our forecast area.

Unfortunately...the return to full sunshine will be accompanied by a
much chillier airmass. Continued cold advection in the wake of the
front will encourage H85 temps to fall to between -10 and -12c by
tonight. This will prevent temperatures from climbing out of the 30s
this afternoon...then light winds and clear skies tonight...mercury
readings away from the lakes will drop off into the teens. There
will even be single digit readings across much of the North Country.
At these levels...temperatures today and tonight will average a
solid 10 degrees below normal.

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
During this period...expansive and strong high pressure will
gradually drift from Lake Michigan to a position just off the New
England coastline. Copious amounts of large-scale subsidence and
dry air attendant to the high will ensure an extended period of fair
dry weather for our region...with mostly sunny skies by day and
mainly clear skies at night only marred by some passing cirrus at
times.

As for temperatures...lingering cold air aloft out ahead of the
advancing ridge will ensure one last day of below normal highs
ranging through the 30s on Tuesday...with excellent radiational
cooling conditions underneath the core of the ridge then allowing
for lows to dip back into the teens to lower 20s Tuesday night.
A developing south-southwesterly return flow of milder air on the
backside of the departing ridge axis will then allow for a nice
recovery in temps to the mid 40s to mid 50s on Wednesday...with
milder lows in the lower to mid 30s then following for Wednesday
night.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
Unfortunately...the period of much warmer and mainly dry weather
previously advertised for both Thursday and Friday appears to be
on increasingly shaky ground. Last night`s 00z/24 run of the ECMWF
suddenly trended toward a much stronger and faster moving cold front
during this time frame...and yesterday the rest of the medium range
guidance also made the same sudden about-face toward this notably
stronger and faster solution...a trend that has continued with the
00z/25 guidance suite.

While Thursday still appears to be fairly mild with highs ranging
from the mid 50s to lower 60s...it now appears that the front will
be strong enough and arrive quickly enough to support a decent
potential for at least some scattered showers by Thursday afternoon...
which will not only result in wetter conditions but also help to
knock temperatures back from what they otherwise could be. The
front itself should then ease its way through our region Thursday
night while producing some additional scattered showers...before
stalling out somewhere over northern Pennsylvania on Friday...in
response to the development of another wave of low pressure over
the southern and central Plains states.

While high pressure and drier air filtering in behind the front later
Thursday night and Friday should help to at least somewhat cut into
any lingering shower activity for areas north of the Southern Tier...
our position north of the main frontal boundary will also likely lead
to a notably cooler day than previously thought...with highs only in
the upper 40s to mid 50s. While definitely still not bad for the end
of March (when normal highs are in the mid to upper 40s)...such readings
would be a far cry from the lower to mid 60s that had previously
appeared likely.

After that...forecast uncertainty increases exponentially for next
Saturday. While all of the medium range models are in good agreement
on the pattern of an elongated wave of low pressure rippling north-
eastward along the stalled out frontal boundary...a high degree of
variability exists with regard to its track and strength. This is
critical to Saturday`s temperature forecast for our area...as the
exact strength and track of the low will influence the location of
the main frontal boundary...which in turn will determine just how
warm or cool we will be. More specifically...a weaker and more easterly
track to the low (such as advertised by the GFS/GEM) would only briefly
nudge the front partially back northward into our region on Saturday...
with much of the region remaining in the cooler airmass to its north.
Combined with clouds and precip...this would likely keep highs confined
to the 40s and 50s if realized. Conversely...the stronger and more
northwesterly track to the low advertised by the ECMWF would result
in the front entirely pushing back northward through our region as
a warm front...with the burgeoning warm sector in its wake potentially
supporting widespread highs in the 60s...and possibly even some lower
70s across inland sections. Suffice it to say...Saturday`s temperature
forecast has a rather high bust potential as of this point in time.

Regardless of the exact track of the low...it does appear that its
approach will at least bring an increased potential for another
round of showers Friday night and possibly on Saturday...when these
could temporarily break off for awhile should the ECMWF idea of a
stronger low/warm frontal passage come to fruition. The passage of
the low and/or its trailing cold front Saturday night and Sunday
should then produce some additional showers while also ushering in
much colder air...with this possibly even turning cold enough for
some snow showers to re-enter the picture.

&&

.AVIATION /08Z MONDAY THROUGH FRIDAY/...
While a cold front has pushed south of our region...it will take a
few more hours for the associated cloud cover to clear out. This
will especially be the case for sites south of BUF and ROC where
cigs will generally range from 1500 to 3500 feet.

As we progress past daybreak...any leftover MVFR cigs will give way
to clearing from the north. This will leave mainly clear skies
across the region for the remainder of today through at least
tonight.

Outlook...
Tuesday through Friday...VFR.

&&

.MARINE...
Generally light winds with a predominantly northerly component will
be found across the Lower Great lakes this morning. Diurnal mixing
will encourage winds to back more to the west during the midday and
afternoon...with some freshening of the winds on Lake Ontario. This
could lead to a short lived period where waves could reach small
craft advisory criteria for the lake Ontario nearshore waters east
of Rochester. Given the time of year...relative low confidence in
the wave forecast and fact that this will be a short lived event in
the second period...will refrain from issuing SCA at this time. The
dayshift can re-evaluate for later packages.

Otherwise...a large area of high pressure centered over the Upper
Mississippi Valley this evening will gradually build across the
Lower Great Lakes late tonight through Wednesday. This will
encourage generally light winds and negligible waves through the
period.

&&

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

&&

$$

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


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