Area Forecast Discussion
Issued by NWS Buffalo, NY

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000
FXUS61 KBUF 191751
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
151 PM EDT Thu Oct 19 2017

.SYNOPSIS...
High pressure will remain anchored along the Mid-Atlantic coastline
through the upcoming weekend with fair weather and above normal
temperatures. The pattern will become more unsettled and cooler
next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
Expansive high pressure will remain centered across the mid-Atlantic
states through the period. The strength of the mid/upper 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. This will
be a dry frontal passage, with just a few hours of cloud cover.
Otherwise, it will be a breezy day, especially across the lake
plains where winds will gust to 35 mph this afternoon. Highs will
again be above normal, with upper 60s in most locations and around
70 from the Genesee Valley into Central NY.

Winds will diminish this evening, but the dry air and lingering
graident flow will limit fog development to only the deepest
Southern Tier valleys. Lows will be in the 40s.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
Friday and Saturday a large and expansive area of high pressure will
remain over the east coast, with abundant sunshine and above normal
temperatures. Highs 10 degrees above normal Friday will be some 15-
20 degrees above normal Saturday as +12 to +14c 850 hPa temperatures
reach our region with the surface high slightly displaced to the
east. Dry ground and a light southerly wind should push temperatures
into the 70s, with an 80F reading not out of the question somewhere
across the lake plain/Genesee Valley...which is typically our
warmest area. Record highs may be just out of reach, which include
for this date: Buffalo 81F/1894, Rochester 80F/2007 and Watertown
78F/1979.

Dewpoints will begin to slowly rise Friday night and into the
weekend...such that valley fog at night will be possible through
southwest NYS.

&&

.LONG TERM /SUNDAY THROUGH THURSDAY/...
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 a mix of sunshine and clouds 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 00z GFS/and most of its GEFS
members shifting the front over our region during the day Monday
while the EC and Canadian models are 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.

&&

.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
VFR conditions will prevail through this evening as high pressure
remains anchored over the Mid Atlantic States, with a ridge
extending northward into the eastern Great Lakes. A weak and dry
cold front will move across the region this afternoon and
evening. Southwest winds will gust to 30 knots across the lake
plains this afternoon.

Expect more VFR conditions tonight as an axis of high pressure
ridges back into the lower Great Lakes region. Dry air and
lingering graident winds will limit the potential for fog
tonight.

Outlook...

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.
Tuesday...MVFR/IFR with showers likely.

&&

.MARINE...
Winds will increase this afternoon as the pressure gradient over the
eastern Great Lakes increases. This will result in small craft
headlines for most of the waters with increasing southwesterly
winds which will shift to the west this evening. Winds will
diminish on Friday as the surface ridge axis moves back closer
to area.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...None.
MARINE...Small Craft Advisory until 8 PM EDT this evening for LEZ020.
         Small Craft Advisory until 2 AM EDT Friday for LEZ040-041.
         Small Craft Advisory from 6 PM this evening to 11 AM
         EDT Friday for LOZ043-044.
         Small Craft Advisory until 11 AM EDT Friday for LOZ045.
         Small Craft Advisory until 8 PM EDT this evening for
         SLZ022-024.

&&

$$

SYNOPSIS...TMA
NEAR TERM...APFFEL/TMA
SHORT TERM...THOMAS
LONG TERM...SMITH/THOMAS
AVIATION...TMA
MARINE...APFFEL/TMA



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