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FXUS61 KBUF 222344

Area Forecast Discussion
National Weather Service Buffalo NY
744 PM EDT Mon May 22 2017

A weak ridge of high pressure will bring dry weather Tuesday through 
most of Wednesday. Low pressure will then bring more rain to the 
region Wednesday night and Thursday.


A weak ridge of high pressure surface and aloft will build over the 
Lower Great Lakes tonight. Subsidence and drying associated with 
this high will continue to support clearing this evening, with the 
eastern Lake Ontario region the last area to clear overnight. The 
clearing skies and a fairly cool airmass will allow for some 
radiational cooling overnight. Expect lows in the upper 40s to around 
50 on the lake plains, with low to mid 40s in the cooler sections of 
the interior Southern Tier and Lewis County.

On Tuesday the weak surface ridge will remain in place from the 
upper Ohio Valley to New England. Meanwhile warm advection and a 
weak mid level shortwave will move northeast across southern 
Ontario. This feature will have little direct impact on our area, 
with any scattered showers remaining north of the Canadian border. 
It will bring some increase in moisture and cloud cover, with both 
mid level clouds and diurnal cumulus developing across the region. 
Stable lake shadows will allow more sunshine northeast of Lakes Erie 
and Ontario. Temperatures will rebound, with highs in the lower to 
mid 70s away from lake influences. Weak synoptic scale flow and 
strong differential heating will allow local lake breezes to develop 
with winds becoming onshore along all the shorelines in the 
afternoon, keeping temperatures cooler within a few miles of the 


Bubble of high pressure becoming centered across New England will 
maintain dry weather across the area through the first half of
Wednesday. Overnight lows Tuesday night will fall back into the
upper 40s to lower 50s. 

High pressure will exit the region Wednesday as a deepening surface 
low slowly tracks into the Ohio Valley. Model tracks differ 
slightly, but most of the guidance eventually tracks this low across 
Ohio Wednesday night and across Lake Erie on Thursday. Increasing 
moisture transport and lift on the front side of the approaching low 
will eventually allow precipiation to blossom across the area. Onset 
time may be slowed a bit from continuity based on slower track of 
approaching surface low. Warm air advection and slower timing of 
precipitation onset should allow high temperatures Wednesday to 
reach the lower to mid 70s.

Does look like there will be at least a solid 6 to 12 hour period of 
fairly steady rain starting late Wednesday in the far west and 
filling in across the rest of the area through Thursday. The steady 
rain should taper to more showery weather by Thursday night as the 
surface low starts to shift east of the area.


Our region will be under the influence of a progressive...northern 
branch of a split flow during this period. While this will allow for 
fairly frequent shower activity...a closed off GOMEX will keep 
rainfall amounts to a minimum. This pattern will also keep 
temperatures from straying too far from normal...but on average... 
they will tend to run a few degrees above typical late May values. 
Breaking this down on a day to day basis...

A stacked storm system over eastern New York Friday morning will 
exit across New England during the afternoon and evening. This will 
keep some showers in place over our region...particularly east of 
Lake Ontario where pops will be raised to likely. Temperatures on 
Friday will climb into the 60s. 

Ridging will build across the Lower Great Lakes late Friday night 
and Saturday. While the models are not convinced that dry weather 
will prevail during this time fairly confident that the 
aforementioned ridging and lack of mid level moisture will translate 
into fair dry conditions. This should also help Saturday afternoon 
temperatures climb into the 70s across most of the western counties. 

As the ridge pushes east of our region Sunday and Monday...the next 
longwave trough will dig across the Upper portions of the 
Mississippi Valley and Great lakes region. This will result in 
deteriorating conditions...particularly late Sunday into Monday. In 
other it stands now we should be able to get through most 
of Sunday before the skies 'open' again. Given the inconsistencies 
between the medium range ensembles though...confidence is lower than 


A weak ridge of high pressure will then build over the Lower Great 
Lakes region tonight and Tuesday with VFR prevailing. Weak warm 
advection and diurnal cumulus will bring some increase in cloud 
cover on Tuesday, with CIGS remaining VFR.


Tuesday Night and Wednesday...Mainly VFR.
Wednesday night...VFR/MVFR with a chance of showers. 
Thursday...VFR/MVFR with showers likely.
Friday...VFR/MVFR with a chance of showers.
Saturday...Mainly VFR.


Weak high pressure will build over the Lower Great Lakes tonight 
through Wednesday, providing a period of light winds and flat wave 
action through the middle of the week.






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