Forecast Discussion for BUF NWS Office
FXUS61 KBUF 231916

Area Forecast Discussion
National Weather Service Buffalo NY
316 PM EDT Wed Aug 23 2017

An large upper level trough over the Great Lakes will make for cool
and mainly dry weather across the region through the rest of the
week. A few spotty light showers will remain possible at times
through Friday morning...before high pressure then brings dry
weather from Friday afternoon right on through the upcoming weekend.


A upper level low is centered over central Quebec this afternoon
with RAP 500mb height analysis showing it is beginning to fill.
Satellite imagery shows a wealth of cumulus/stratocu over the
majority of western and central NY due to weak instability of cool
air within trough over warmer land. Radar shows a broken band of
showers extending from the SLV west across Lake Ontario into
southwest Ontario Province associated with a vort max and associated
weak surface trough. These showers will push south into western and
north central New York through the late afternoon and evening with
mainly spotty hit and miss coverage except across the North County
where the line is a little better organized. There is also a report
of some graupel at CYGK which can also be expected in heavier cores
in this cool airmass as the trough pushes across the area. 850mb
temps will slip down to 8C holding afternoon highs mostly in the
lower to mid 70s or about 5 degrees below normal.

Tonight, the diurnally-driven cloud cover and scattered showers
should taper of with the loss of daytime heating. High pressure
building south out of central Canada will then feature mainly dry
weather through late tonight or early Thursday morning. Continued
cold air advection will lower 850mb temps to 6C which will be enough
top support development of some lake effect clouds and scattered
light showers along the south shore of Lake Ontario. Otherwise, the
dry airmass will bring a cool night with low temperatures slipping
back into the upper 40s inland to mid 50s near the lakeshores.
Patchy Southern Tier river valley fog is also expected to develop

Thursday, a pool of seasonably cool air within the longwave trough
over the Great Lakes will combine with an embedded shortwave
pivoting over the lower Great Lakes to support chances for scattered
diurnal showers with some lake enhancement. 850mb temps of around 6C
will contribute to the lake enhancement with equilibrium levels
rising to around 10kft. While the majority of the activity will
likely be south/east of the lakes the synoptic support from the
passing shortwave leaves no area clear from a scattered/isolated
shower during the day. There again could be a risk of some graupel
or small hail in any more enhanced shower cores. The cool airmass
will limit surface highs to the 60s or some 10 degrees below normal.


Thursday night lake effect rainshowers will develop southeast
of Lakes Erie and Ontario in the cold northwest flow. Overnight
lows will range from the upper 40s across the interior southern
tier and the north country to the mid 50s along the lake shores.

By Friday morning the lake effect rain showers will be waning as
drier air builds across the region. This should occur before sunrise
off Lake Erie and during the early morning off Lake Ontario...
followed by increasing amounts of sunshine during the afternoon.
Highs will continue to be about five to ten degrees cooler than
normal, struggling to get within a few degrees of 70.

Expect mainly clear skies Friday night as surface high pressure
builds into the eastern Great Lakes. Lows dropping into the low to
mid 40s across the interior sections and north country to the low
50s near the lakes.


High pressure will be anchored over the Northeast this weekend, with
a cool NW flow aloft providing for comfortable levels of humidity
and just fair weather afternoon cumulus. The upper level trough will
exit Monday...and we`ll be within a quasi-zonal flow aloft through
the remainder of the period with a upper level cut off low over the
midwest. We should hold onto our dry pattern through at least
Tuesday, if not Wednesday depending upon how quickly eastward this
upper level low advances.

The end of the month will finish with comfortable late summer
temperatures...near the average of mid 70s...and dewpoints will be
comfortable, generally in the upper 40s to lower 50s. Nights may
become cool, with mid 40s possible early in the period across
interior valleys.


VFR conditions will continue to prevail today and tonight with
diurnal cumulus/stratocu this afternoon dissipating this evening with
the loss of daytime heating. A broken band of scattered light showers
and possibly some graupel will shift southeast across western and
central NY this afternoon along a weak surface trough.

Tonight, mainly dry weather expected until some scattered light lake
effect showers develop late overnight along and south of the south
shore of Lake Ontario. This cloud cover will run in the MVFR range
for most sites through the mid-late morning hours but will tend to
lift/scatter out going into the afternoon with better diurnal mixing.

Thursday...VFR/MVFR with a chance of showers.
Friday...A chance of morning showers southeast of the lakes...otherwise
Saturday through Monday...VFR.


A brisk westerly flow of cooler air is in place this afternoon
maintaining Small Craft Advisories on both lakes. Winds and waves
will diminish tonight and Thursday as the responsible low pressure
system pulls further away from our region...with high pressure then
building into our region and providing relatively tranquil
conditions for Friday and the upcoming weekend.

All the above stated...there will also be the chance for a few
waterspouts over the next few days as a cool airmass crosses the
warmer lake waters.


A brisk westerly flow of cooler air will persist across Lake Ontario
today...before diminishing tonight. Coupled with already high lake
levels...the increased winds and wave action will continue to bring
increased shoreline erosion and lakeshore flooding to the east half
of Lake Ontario through today and into this evening. The static lake
levels have dropped since late spring/early summer, so the impacts of
this event are not likely to be as significant as earlier in the season,
but should still be enough to warrant a continued Lakeshore Flood


NY...Lakeshore Flood Warning until 11 PM EDT this evening for
     Beach Hazards Statement until 11 PM EDT this evening for
     Beach Hazards Statement until 8 PM EDT this evening for NYZ002-
MARINE...Small Craft Advisory until 8 PM EDT this evening for LEZ040-
         Small Craft Advisory until 5 AM EDT Thursday for
         Small Craft Advisory until 11 PM EDT this evening for
         Small Craft Advisory until 2 AM EDT Thursday for LOZ045.




NWS BUF Office Area Forecast Discussion