Forecast Discussion

Forecast Discussion for BUF NWS Office
FXUS61 KBUF 240046

Area Forecast Discussion
National Weather Service Buffalo NY
846 PM EDT Thu May 23 2019

The passage of a cold front this evening will introduce a cooler and
notably drier airmass into our region. This will be accompanied by
mainly fair dry weather on high pressure will pass over
the Lower Great Lakes. Unfortunately, conditions will then
deteriorate Friday night and Saturday as a pair of frontal systems
will push through the forecast area.


While there may be a leftover shower east of Rochester this evening
as a cold front moves through...the widespread showers and strong
thunderstorms have exited our region. Drier and cooler air will now
overspread the forecast area overnight with temperatures settling
into the lower 50s.

High pressure over the Upper Great Lakes this evening will gradually
build across our forecast area on Friday. While this will guarantee
fair dry weather for the bulk of the region...a residual cyclonic
flow aloft could still support some morning cloud cover as well as a
stray shower or two east of Lake Ontario.


Surface based ridging extending southeast from James Bay will
consolidate over NY/PA and maintain firm control across the lower
lakes Friday night. Look for quiet and dry weather across the region
with generally clear skies until late as an approaching warm front
introduces some mid and high level clouds. Lows by daybreak will
range from the upper 40s to lower 50s across the forecast area.

Saturday, the surface high just to our southeast will quickly exit
the area and off the NJ coast during the early morning hours.
Meanwhile, weak surface low pressure over Ontario Canada will track
east while lifting its warm front into Western NY. Isentropic lift,
supported by a 30 knot LLJ, and copious amounts of moisture being
transported northeast into the region (PW values ramping up to near
1.5 inches) will likely lead to increasing chances of showers and
thunderstorms Saturday morning. As the warm front continues to lift
northeast across the area into the North Country, behind the front
there maybe a brief lull in storm activity across Western NY before
the cold front arrives later in the day/evening. Again, another
round of storms will be possible with the cold front but with the
front arriving so late in the day, instability won`t be maximized
and waning to an extent. So the potential for widespread severe
weather at this point will be limited due to the timing of the cold

Otherwise, with temperatures climbing into the 70s and a moisture
laden atmosphere it will likely be a humid day across the region.

Saturday night, low pressure over NE. Ontario Canada will track
further NNE into Quebec with its trailing cold front slowly pushing
south and southeast into PA where it will stall overnight.
Meanwhile, a weak wave is forecast to track out of the Midwest along
this stalled frontal boundary to our south on Sunday. Although,
various model guidance packages differ on the positioning of the
stalled front and the strength of the wave which is forecast to pass
to our south. For now, have kept chance POPs in the forecast to
account for the uncertainty.

Sunday night, sprawling surface ridging over Ontario Canada will
track east with the axis of the ridge positioned over James Bay and
bisecting Western NY. This feature will introduce quiet and dry
weather across the forecast area into Monday. Any residual showers
or thunderstorm behind the departing wave will quickly end Sunday
evening with mainly clear skies developing overnight. Lows will fall
back mainly into the 50s under mainly clear skies by daybreak


Increased ridging will begin on Monday over the eastern third of the
country. This will provide mostly rainfree conditions for Monday. As
the ridge strengthens over the southeast U.S., a similar scenario to
this weeks weather will take shape. The ridge over the southeast
U.S. will cause waves of low pressure to trek northeast out of
western half of the country where a trough will be in place. Waves
of low pressure will increase the chance for showers and
thunderstorms from Tuesday through Thursday across western and north
central NY.

Ahead of these areas of low pressure warming temperatures on Tuesday
and Wednesday will bring highs across the area to the upper 70s to
mid 80s. A passing cold front late Wednesday/early Thursday will
bring slightly below normal temperates to the area with highs in the
mid to upper 60s.


VFR conditions will be found across the region through the first
half of tonight. Conditions may deteriorate a bit late tonight and
early as lower cigs will settle south from Lake Ontario. VFR cigs
will likely lower to MVFR levels for most TAF sites between 09 and

MVFR cigs Friday morning will then give way to VFR conditions as
diurnal mixing will prompt cigs to lift and eventually dissipate by
midday. The associated area of high pressure will assure fair dry
weather for Friday and Friday evening...although a stray shower
cannot be ruled out for sites east of the Tug Hill.

Friday night...VFR/MVFR with a chance of showers and thunderstorms
Saturday...VFR/MVFR with showers likely and a chance of thunderstorms.
Some storms could again produce gusty winds.
Sunday...VFR/MVFR with a chance of showers and thunderstorms.
Tuesday...Mainly VFR with a chance of showers and thunderstorms.


Gusty winds in the wake of a cold front will support small craft
advisory conditions this evening...and for Lake Ontario into Friday

Winds will then subside during the day Friday as high pressure will
push east from the Upper Great Lakes. Generally light winds and
negligible waves can then be anticipated Friday night and Saturday.


A cold front will cross Lake Ontario this evening. Behind this
front moderately brisk westerly winds will produce higher waves
on Lake Ontario, with these combining with very high lake levels
to bring the likelihood of lakeshore flooding to the shorelines
of Wayne...Northern Cayuga...and Oswego Counties. Winds and
flooding concerns will then diminish on Friday as high pressure
builds into the area.


NY...Lakeshore Flood Warning until 11 AM EDT Friday for NYZ004>006.
MARINE...Small Craft Advisory until 11 PM EDT this evening for LEZ020-
         Small Craft Advisory until 11 AM EDT Friday for
         Small Craft Advisory until 2 AM EDT Friday for LOZ042.
         Small Craft Advisory until 11 AM EDT Friday for LOZ044.




NWS BUF Office Area Forecast Discussion