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Area Forecast Discussion (AFD)

Issued by Buffalo, NY (BUF)

FXUS61 KBUF 170309

Area Forecast Discussion
National Weather Service Buffalo NY
1109 PM EDT Mon Sep 16 2019

High pressure will then bring a prolonged stretch of spectacular 
late summer weather for the rest of the week, with temperatures 
climbing to well above normal by late in the week.


Stubborn low level cloud cover that continues to hang on over the 
western third of NYS, westward into southwestern Ontario Province 
will continue to slowly dissipate/press off to the south and 
southwest through the early overnight. Looking at area 00Z 
soundings, appears plentiful moisture (PWAT values just over 1 inch) 
trapped in the low levels under stout subsidence inversion aloft is 
the main reason for the very slow dissipation of the low clouds. 

Otherwise, overnight into Tuesday, high pressure over Ontario and 
Quebec will build further south into the area and remain stationary. 
This will help to scour out any leftover clouds overnight across 
western NY into the Southern Tier, thereby leading to mainly clear 
skies for later tonight and Tuesday. Coupled with light winds and a 
much drier airmass featuring dewpoints in the 40s and PWATs down 
below 0.5 inch (eventually across western areas), this should lead 
to excellent conditions for radiational cooling. Expect overnight 
lows to fall to the lower to mid 40s across the north country and to 
the mid to upper 40s in most other locations, with only the 
immediate lakeshores and portions of far western NY failing to drop 
below the 50 degree mark. On Tuesday, under mostly sunny skies, 
highs will be mainly in the low to mid 70s, with upper 60s reserved 
for the higher terrain.


Surface high pressure will be over/just to our north Tuesday 
night...with the surface feature to our east Wednesday and Thursday.
It will continue to be dry this period, with a strong upper level 
ridge of high pressure supplying clear skies and mild temperatures 
that will be around 5F above normal at night...and 5-10F above 
normal during the day. 

The only real change to the going forecast was to add some river 
valley fog across the Southern Tier each morning...while some 
patches of fog are also possible in the valleys east of Lake Ontario.


Given the influence of ridging, dry conditions persisting through at 
least Saturday night with very mild temperatures continuing.   

A large stacked storm system over central Canada during the weekend 
will eventually push a Pacific based cool front through our region. 
The front may be close enough later Sunday into Monday to warrant
the mention of a few showers.


VFR conditions expected for the entire TAF period. Only exceptions 
will be some isolated pockets of MVFR cigs across the interior 
Southern Tier, east of KJHW through through the early overnight. The 
other exception will also be across the interior Southern Tier, 
where localized IFR will be possible in typical valley fog that will 
form late tonight, lasting through mid morning Tuesday. Otherwise, 
stubborn low level VFR decks that are still hanging on over the 
western third of NYS, westward into southwestern Ontario Province 
will continue to slowly dissipate/press off to the south and 
southwest through the early overnight, leaving behind mainly clear 
skies as surface high pressure continues to build south across the 
area right through Tuesday.


Tuesday through Saturday...Mainly VFR...with localized IFR 
in Southern Tier valley fog possible each night/early morning.


Expect some light chop across the eastern shores on Lake Erie and 
the southwestern shores on Lake Ontario through the early overnight. 
Otherwise, high pressure building back across our region will result 
in light winds and minimal wave action for the rest of the week.