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Area Forecast Discussion (AFD)

Issued by Buffalo, NY (BUF)

FXUS61 KBUF 191856

Area Forecast Discussion
National Weather Service Buffalo NY
256 PM EDT Wed Jun 19 2019

Another warmer day today with just a few showers or thunderstorms 
into early evening inland from lake breezes. Widespread moderate
to heavy rain is expected Thursday into Thursday night as moisture 
laden system crosses the region. Dry weather will follow the system 
into the weekend.


Another day of mainly quiet weather with a mix of cu and thick 
cirrus keeping lid on any expansive convection. Just starting to
see a few showers popping up over northwest PA which may drift 
across the western Southern Tier in the next few hours. Otherwise,
looks pretty nice into the evening with readings in the upper 
70s to around 80F. 

Well advertised low pressure system that will bring widespread 
moderate to heavy rain continues to develop over central CONUS this 
afternoon with lowest MSLP currently near St. Louis, MO at 
1005mb. Warm front extends east from the low then merges with 
front that has been stalled out across Ohio and Pennsylvania 
last couple days. More humid conditions south of that front with
dwpnts in the upper 60s to near 70F. Initially the low rides 
along the front, but later tonight into Thursday, the low begins
to slide more north across forecast area in response to sharper
shortwave trough that moves across the lower Great Lakes. Now 
appears this potential heavy rain event comes in at least a 
couple episodes. First period of moderate to heavy rain, 
supported by initial warm air advection ahead of sfc low arrives
in the morning hours over western NY and by midday/early 
afternoon east of Lake Ontario toward the Dacks. 

Most instability remains south of this first area of rain, but 
strong moisture flux convergence and PWATs rising to 1.75 inches 
will offset that somewhat. Main trend from 12z high res convective 
allowing models (CAMS) and high res ensemble output (HREF) is a 
notable shift to the north for axis of heavier rain, now projected 
mainly across the northern tier of counties along Lk Ontario 
compared to along the far Southern Tier. This brings these models in 
line with what larger scale global models were showing for a while 
now. Does appear that initial round of heavier rain tapers off mid 
aftn west and late aftn for our eastern forecast area. After the 
last few days of mild temps, readings will be held down in the upper 
60s to maybe an isolated 70F reading.

After sfc low passes by over New England while deepening on Thursday 
night, another round of rain may affect especially the northern 
forecast area Thursday evening. HREF very high with QPF compared to 
blend of other guidance. This wave is just pushing into western KS 
attm and there are differences in extent and location of heavier 
precip. Upshot is there were too many uncertainties in total qpf and 
location of said higher QPF, especially with substantial changes to 
previous runs to do any kind of flood watch at this point. If it 
would have been issued, it likely would have included all of the 
forecast area. Will let evening and mid shifts look at latest trends 
and issue watch if needed. With 1,3 hr FFG mainly in the 1.5 to 2 
inch range, seems that our basins would be able to handle 1-2 inches 
of total rainfall across area. If rainfall ends up more in the 2-3 
inch range, as the higher end of the HREF shows, probably will see 
at least isold hydro issues.


The longwave pattern will become fairly amplified by Friday 
with an upper level low over the Intermountain Region while a 
ridge develops downstream over the plains. This will result in 
slow moving surface high pressure over the Great Lakes region on
Friday that will migrate to the northeast US by Sunday. 

The result will be dry and seasonable weather WNY leading into and 
through the weekend.


A better chance of showers and possibly a few thunderstorms 
will arrive Sunday night and Monday as a much more humid airmass
arrives and several shortwaves begin to move around the top of 
the developing ridge over the Southeast States. Rain chances 
will linger into Tuesday as a deeper trough digs into the Great 
Lakes. Temperatures will become summer-like by early next week, 
with highs in the lower 80s Monday along with moderate humidity.


Showers and a possible thunderstorm are expected mainly away from 
the lakes into early this evening. The best chance for any 
thunderstorms will be across the western Southern Tier at KJHW. MVFR 
cigs likely at KJHW and a brief period of IFR possible in any 
thunderstorms. Elsewhere, expect VFR conditions through tonight 
before rain moves in late tonight over western NY.  


Thursday...Deterioration to MVFR/IFR with periods of rain 
developing. A thunderstorm is also possible, especially at KJHW. 
Friday...MVFR/VFR with a chance of early morning showers well 
southeast of KJHW-KROC-KART.
Saturday and Sunday...VFR.
Monday...Chance of showers. VFR.


Low pressure is expected to track across the Lower Great Lakes on 
Thursday. Winds and waves may approach Small Craft levels late 
Thursday into Friday depending on the strength of this system.





LONG TERM...Hitchcock