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Area forecast discussion
National Weather Service Buffalo New York
1018 PM EDT Tue Sep 17 2019

Synopsis...
strong high pressure will provide US with a prolonged stretch of
magnificent late Summer weather for the rest of the week, with
temperatures climbing to well above normal by late in the week. The
next chance of rain will not arrive until Sunday night.

&&

Near term /through Wednesday night/...
infrared satellite imagery showing clear skies regionwide late this
evening. High pressure will remain centered over Quebec tonight,
with a ridge extending down into the eastern Great Lakes. Associated
subsidence and dry air will keep clear skies in place overnight with
excellent radiational cooling conditions. Lows will drop into the
upper 40s to lower 50s in the lake plains, with low to mid 40s in
the typically cooler southern tier valleys and east of Lake Ontario.
Some of the cool spots in the north country may even drop into the
upper 30s with a few light patches of frost not out of the question.
River Valley fog will develop once again across the western southern
tier late tonight and Wednesday morning.

Surface high pressure becomes centered over northern New England
Wednesday. A mid-level ridge will move across the Great Lakes basin
during the day maintaining dry and mostly clear conditions. High
temperatures will be similar to today (tuesday) with highs in the
low 70's across lower elevations and mid to upper 60's on the higher
terrain. Temperatures at 850mb will start to climb across western
and north central New York Wednesday night. This will begin the slow
warming trend for Thursday and into the weekend. Valley fog is
expected across the southern tier and Finger Lakes late Wednesday
night into Thursday night again. Low temperatures will range from
the lower 50s on the lake plains to the 40s in the southern tier
valleys and east of Lake Ontario.

&&

Short term /Thursday through Saturday night/...
..magnificent weather through the period...

A building mid to upper level ridge will move into the eastern Great
Lakes Thursday. Drier air will filter into the region, decreasing
precipitable waters even more. Temperatures at 850mb will be on the rise and
after a night with lows in the 40s to near 50f, temperatures on
Thursday will climb into the mid to upper 70's across the lake
plains and the low 70's on the higher terrain.

An impressively persistent...high amplitude 500 mb ridge will remain in
place through rest of the period across the eastern half of the
continent. Its accompanying area of high pressure at the surface
will be equally dominant in nature...as it will spend the majority
of the time frame being sprawled over New England and the mid
Atlantic states. This will guarantee fair dry weather across our
forecast area with subtle warm advection leading to steady day
to day warming.

850 mb temps that will start off between 8 and 10c will slowly warm to
the mid teens by the end of the work week and into the first half of
the weekend. This will allow some of the normally warmer areas (lake
plains, valleys) to reach into the lower 80s Friday afternoon and
Saturday afternoon. Some hint that there could be some more clouds
on Saturday over western New York into the southern tier as initial warm
air advection occurs, but will not alter the warmer temperatures as
looks like any cloud cover would be short lived and shallow in
depth. Though primary warm front is forecast to surge by to the
north Saturday into Saturday night, initial push of low-level
moisture advection with dwpnts rising into the 60s along with pocket
of MLCAPES up to 500j/kg could support a few shra/tsra over Lake
Ontario region and toward St. Lawrence Valley later Saturday night.
Better chances though, by far, likely end up well to the north
closer to warm front. With the warm front to the north Saturday
night expect a warmer night with readings in 60s.

&&

Long term /Sunday through Tuesday/...
as surface high moves off the mid Atlantic coast into the western
Atlantic through Sunday afternoon, a deepening southerly flow will
advect increasingly more humid air into our region. We can still
expect clear to partly cloudy conditions, with some increase clouds
toward the end of the day and just the slight chance of a shower
toward the evening, best chance across northwest areas. Expect
another day featuring afternoon highs in the 80s, with some upper
70s reserved for the higher terrain.

A pre-frontal trough will move through late Sunday night, with the
cold front following behind knocking on the door by Monday morning,
then pressing southeast across the area on Monday. This will support
the likelihood for a round of showers late Sunday night and Monday,
with steadier showers tapering from northwest to southeast by late
in the day. Will keep mention of thunder out of the forecast this
far out (for now), as instability looks fairly meager at this point.

Will keep a chance of showers in the forecast Monday night as main
axis of the upper trough swings through, with a slight chance of
showers from The Finger lakes east on Tuesday, as another shortwave
pivots around the back side of the departing main upper trough.

High temperatures in the 70s on Monday, will trend downward to the
60s for Tuesday in the seasonably cooler airmass behind the cold
front.

&&

Aviation /02z Wednesday through Sunday/...
high pressure will drift from Quebec tonight to northern New England
Wednesday, with a ridge extending back into the eastern Great Lakes.
This will provide clear skies most of the time, with nothing more
than a few patches of high/thin cirrus and perhaps a few diurnal
cumulus Wednesday afternoon of little vertical extent. VFR will
prevail through Wednesday with the exception of southern tier River
Valley fog. This will bring local IFR late tonight through Wednesday
morning. The fog is not expected to impact kjhw.

Outlook...
Thursday through Sunday...mainly VFR...with localized IFR in
southern tier valley fog possible each night/early morning.

&&

Marine...
high pressure will provide our region with light winds and minimal
wave action for the rest of the week. The one minor exception will
be on Lake Erie and Western Lake Ontario, where a brief period of 10-
15 knot northeast winds will develop again Wednesday afternoon,
bringing waves up to around 2 feet briefly.

&&

Buf watches/warnings/advisories...
New York...none.
Marine...none.

&&

$$

Synopsis...Hitchcock/jjr
near term...Hitchcock/hsk

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