Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 220432
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
1232 AM EDT Sat Apr 22 2017

.SYNOPSIS...
High pressure over the northern plains will arch across the Great
Lakes Saturday afternoon...and while the day will start off
cloudy...improving conditions with clearing skies can be
anticipated. The fair weather will continue through Sunday when a
solid 10 degrees can be added to the high temperatures. Our region
will continue to dry out through at least Monday as high pressure
will nose south across the Lower Great Lakes from northern Ontario.

&&

.NEAR TERM /THROUGH TODAY/...
A stacked low over western Quebec at midnight will slowly push east
during the overnight while its associated mid level trough will
approach the region from the north. Nominal hgt falls and a wealth
of low level moisture within this environment will keep skies cloudy
through the first part of Saturday...with a few spots possible
picking up some sprinkles. Temperatures by daybreak will range from
the mid and upper 30s across the Southern Tier and over the Tug Hill
to the lower 40s for the bulk of the lake plains.

On Saturday...widespread cloud cover in the morning will gradually
thin out and give way to some sunshine from west to east as the day
matures. In fact...mostly sunny skies are anticipated west of the
Genesee Valley by mid afternoon. It will be relatively cool
though...as H85 temps at or below zero c and delayed clearing will
only allow afternoon temperatures to climb to within a few degrees
of 50. Normal highs for this time of year are closer to 60.

&&

.SHORT TERM /TONIGHT THROUGH MONDAY NIGHT/...
This afternoon, surface analysis places an area of low pressure over
western Texas, a broad area of high pressure over the Northern
Plains, and another area of low pressure to the northwest of Lake
Winnipeg. The upper air pattern is featuring a split flow, with
water vapor imagery displaying a streamer of vorticity/developing
shortwave pushing southeastward across the Rockies, while a broad,
cyclonic flow remains across central and northern Canada.

For the Saturday night through Monday night time period, our region
will remain squeezed between these two storm features, with surface
high pressure from the plains nosing eastward enough to likely
maintain a narrow wedge of dry weather across the Eastern Great
Lakes region.

The northern feature will eventually drag a frontal boundary across
southern Ontario and southern Quebec, but this should remain just
far enough northward to keep rain showers north of the border. The
southern feature will slowly track across the Southeast this period.
This feature will tap into some Atlantic moisture, spreading clouds
northward across our region for Monday night, and perhaps a shower
late near the state NY/PA line.

We will get off to a frosty start this period, with clearing skies
Saturday night allowing for temperatures to drop into the 30s, with
inland areas falling to around the freezing mark. Abundant sunshine
Sunday with a modifying airmass aloft will allow for a return to
upper 50s, to lower 60s...which is seasonable for this time of year.
Though 850 hPa temperatures will be warmer Monday, the surface high
will increase the northeast flow, with slightly cooler air
undercutting the warming at 850 hPa, and will likely bring surface
highs a degree or two cooler than Sunday.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
On Tuesday model consensus has a longwave ridge across the Eastern
U.S. with a cut-off low somewhere in the mid-Atlantic region. The
position of cut-off lows can be difficult to predict, with a chance
showers from this system will clip our region on Tuesday. Otherwise,
it will be pleasantly warm with highs in the 60s.

This low will weaken, with the next system still far enough upstream
so that dry weather is likely Tuesday night into Wednesday. The
longwave ridge will promote even warmer temperatures, with southerly
winds downsloping and helping the lake plains climb well into the
70s.

After this, model consensus continues to be in good agreement with a
shortwave and associated surface low forecast to track from the
Central Great Lakes to Southern Ontario. This fairly weak boundary
should result in a scattered line of showers with some thunderstorms
possible late Wednesday afternoon and evening. The front should push
through the region, with mainly dry weather expected for Thursday.
Consensus 850mb temperatures are considerably cooler than 00Z
guidance, but warmer temperatures are not all that far off. As a
result will nudge forecast highs down a bit, but still stay above
consensus temperature guidance in case the boundary does not push
all the way through.

On Friday, a stronger system will lift across the mid-west with 12Z
runs of the GFS/GGEM/ECMWF in remarkably good agreement considering
the timeframe. This system should track into the Upper Lakes late
Friday, which will lift an associated warm front into (or across)
our region on Friday. The warm front may result in some showers on
Friday. There also will be much above normal temperatures on the
warm side of this boundary with highs likely to climb well into the
70s on Friday.

Looking ahead to next weekend, temperatures are likely to be well
above normal, with a summer-like pattern developing. Highs are
likely to be in the 80s with 90 not out of the question.

&&

.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
VFR conditions across the majority of the region at 04z will give
way to at least MVFR cigs as we push into the wee hours of Saturday
morning. Cigs are already at MVFR across a portion of the southern
tier and Finger Lakes region. For these areas...IFR cigs are likely
after 09z.

On Saturday...the low cigs will lift to VFR levels by midday with
general cigs then giving way to clearing as high pressure will nose
across the region during the afternoon and evening.

VFR conditions can be expected Saturday night.

Outlook...

Sunday and Monday...VFR.
Tuesday and Wednesday...Mainly VFR with a chance of showers.

&&

.MARINE...
Low pressure will move slowly east across Quebec through the
overnight. Winds will become more northwest into Saturday morning
with choppy conditions continuing on both lakes. High pressure will
then build into the Great Lakes later Saturday through Sunday with
light winds and flat wave action.

&&

.HYDROLOGY...
Rainfall of 1-2 inches fell Thursday and Thursday evening
across the bulk of the area, with a few locations from eastern
Erie County through Genesee County and northern Livingston
county seeing over 2 inches. This has resulted in extensive
ponding of water in low lying and poor drainage areas, and high
water on many small streams and creeks.

The larger rivers and creeks have also seen significant rises.
The faster responding creeks have already crested and are
receding, with some slower responding rivers and creeks still
rising or near crest. River flood warnings remain in place for
the Genesee River near Avon and also for all of Ellicott Creek.

Dry weather is expected through the weekend into early next
week, which will allow all the rivers and creeks to recede.

&&

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

&&

$$

SYNOPSIS...RSH
NEAR TERM...RSH
SHORT TERM...THOMAS
LONG TERM...APFFEL
AVIATION...RSH
MARINE...CHURCH/RSH
HYDROLOGY...HITCHCOCK/RSH



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