Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 182315

Area Forecast Discussion
National Weather Service Buffalo NY
715 PM EDT Wed Oct 18 2017

High pressure over the Mid-Atlantic coastline will remain anchored
there through the week, bringing dry weather, plenty of sunshine and
above normal temperatures to our region.


IR satellite imagery showing completely clear skies across the area
this evening.

Clear, mild and dry conditions will continue through the overnight.
There should be just enough of a gradient flow and dry boundary
layer to greatly limit or prevent valley fog overnight across the
western Southern Tier. Lows will range from the lower 50s on the
lake plains to the mid 40s in the cooler Southern Tier valleys and
Lewis County.

Thursday, The strength of the mid level ridge will steer the next
upper level wave well north of the Great Lakes through northern
Ontario and James Bay. The weakening cold frontal trough extending
southward from this system will sweep across western and north
central New York during the afternoon. There will be little fanfare
with this through as the airmass is so dry and surface ridge still
remains in place. Looks like at best we`ll see a brief period of
enhanced cloud cover with the trough, but that should be about it.
Highs will again be above normal, with upper 60s in most locations
and around 70 from the Genesee Valley into Central NY.


A large upper level ridge and corresponding area of surface high
pressure will slowly move over (and then east) of the Great Lakes
region and Northeast US Thursday Night through Saturday Night.  The
result for Western and Central NY will be continued dry weather with
above normal temperatures.  With the high directly overhead Saturday
Night, some valley fog will be possible in deep river valleys
despite the overall dry airmass.  But, with the growing season
essentially over, there will be less available moisture from
transpiration. So, the typical valley fog season is nearing its end.


A progressive amplified mid-level pattern across the CONUS will
bring changeable weather from this weekend into next week. Sunday a
seasonably strong 500mb ridge over the East Coast with surface high
pressure over the western Atlantic will bring another gorgeous day
with plenty of sunshine across western and north central New York.
Southerly flow will help temperatures run 15 to 20 degrees above
normal with highs forecast to climb into the low to mid 70s.

A change to cooler and more unsettled weather then arrives with the
start of next week. A fast moving shortwave trough and surface cold
front are forecast to shift into the western/central Great Lakes
Sunday night. Differences in timing of when the front reaches
western NY show up by Monday with the 12z GFS shifting the front
over our region during the day Monday while the EC is about 12 hours
slower holding it off until Monday night. Have taken down POPs a bit
to low chance range on Monday favoring the EC timing then bringing
likely POPs into WNY for Monday night. Temperatures will remain on
the mild side Sunday night and Monday with strong cold advection not
arriving until later in the week.

Tuesday and Wednesday should feature unsettled conditons as the
frontal zone stalls across our region and one or more waves of low
pressure shift north along the front. Have included likely POPs for
Tuesday as both GFS/EC models are in agreement with a surface low
lifting north across New York. The GFS shows a potentially moisture
rich airmass will move into place along the front with a connection
to the Gulf of Mexico could push PWATs above an inch or more. WPC
Day 6-7 QPF shows a swath of 1.25-2.5 inches of rain over western
and central New York.

Chance POPs are featured for Wednesday as the mid-level trough and
cold advection support potential showery weather. Temperatures will
run near normal (mid-upper 50s) Tuesday then below normal for
Wednesday as 850mb temps dip to or below zero 0 which would support
temps likely struggling to break above 50 in many locations.

No snow is expected through Day 7/Wednesday but temps may cool
enough Wednesday night for potential some wet snow to mix in in the
higher terrain. Stay Tuned.


VFR will prevail through Thursday as high pressure remains anchored
over the Mid Atlantic States, with a ridge extending northward into
the eastern Great Lakes. There will be enough gradient wind
overnight to prevent river valley fog across the western Southern
Tier. On Thursday a weakening cold front will move across the region
during the afternoon and evening. This front will remain dry, with a
few hours of clouds with bases around 5K feet. It will become quite
breezy again Thursday, with gusts of around 20 knots for much of the
area, and around 30 knots northeast of Lakes Erie and Ontario.


Friday through Sunday...VFR except for local IFR in river valley fog
each late night and early morning.
Monday...VFR/MVFR with a chance of showers.


Winds will increase again Thursday as the pressure gradient over the
eastern Great Lakes increases. This will bring a round of Small
Craft Advisory conditions to the eastern ends of the Lakes Erie and
Ontario on a southwest wind for Thursday and Thursday night. Small
Craft Advisory winds will also develop for the Buffalo Harbor and
Saint Lawrence River. Small craft conditions may spread to most of
Lake Ontario on a westerly wind as we move into Friday.


MARINE...Small Craft Advisory from 8 AM Thursday to 2 AM EDT Friday for
         Small Craft Advisory from 10 AM to 8 PM EDT Thursday for
         Small Craft Advisory from 8 AM Thursday to 11 AM EDT
         Friday for LOZ045.
         Small Craft Advisory from 6 PM Thursday to 11 AM EDT
         Friday for LOZ044.
         Small Craft Advisory from 11 AM to 8 PM EDT Thursday
         for SLZ022-024.



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