Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 280828

Area Forecast Discussion
National Weather Service Buffalo NY
428 AM EDT Tue Mar 28 2017

A weak area of low pressure will cross the region today, bringing
scattered rain showers across the region, while also producing some
fog. A light northerly wind through tonight will maintain a cloudy
sky across the region, while Wednesday and Thursday should feature
mostly sunny skies. Temperatures will remain seasonable through the


Surface analysis this morning displays two weak areas of low
pressure, one just to the north of Lake Ontario, and a second and
slightly stronger area of low pressure over OH. Regional radars
display scattered rain showers across southern Quebec associated with
the first low, with activity nearing the Saint Lawrence Valley.
Additional rain showers that have more coverage area are located
across OH/PA.

Temperatures of both air and dew point remain mild this early
morning. With a moisture rich environment and weak winds areas of
fog will likely form, thickest near the lake shores and hills of SW
NYS and Tug Hill region, and becoming more patchy across the Finger
Lakes region.

For today a weak frontal boundary between these two areas of low
pressure will pass across the region. Along the front rain shower
activity will increase, along with some areas of fog forming as
surface dew points peak ahead of the front. Greatest chances for
rain showers will be across the So. Tier, closer to the weak surface
low. As this weak front passes today winds will veer to northerly by
this afternoon. While some fog may linger along the southern Lake
Ontario shoreline, the northerly winds will create a deck of low
stratus, with surface visibilities improving, but thick clouds
remaining. This northerly flow will continue through tonight as
surface high pressure nears the region, with clouds likely to linger
as moisture becomes trapped beneath a subsidence inversion.

Rain showers will also diminish through the afternoon and evening as
this surface high pressure nears the region, and surface low
pressures exit to the east. Overall total rain today and into this
evening will remain on the light side, with most areas remaining
below a quarter of an inch.

Temperatures today will be slightly cooler within the northerly wind
flow, with highs around normal, peaking in the upper 40s. Tonight
the lingering clouds will keep most areas just above the freezing
mark, though thin clouds, or even some late clearing across the
North Country will allow for overnight temperatures to drop to
around 30.


High pressure transiting Hudson Bay will extend ridging into the
Great Lakes region during the mid-week period. This will provide a
period of quiet weather and at least some sunshine. However, things
start downhill again Thursday night, as a southern stream closed low
ejects from the southern Rockies. Associated precipitation will
begin to push into the region from the west on Thursday night.

Wednesday through Thursday, look quiet, with an upper level
shortwave ridge axis moving overhead. Shallow cool air will be
pushing into the region on a general northerly low level flow with
850 mb temperatures down to around -8C. This will try to generate to
generate some lake clouds, especially south of Lake Ontario, though
a dry airmass will hinder this process. Still, expect no worse than
partly cloudy skies for Wednesday and Wednesday night with plenty of
locales mostly clear.

Thursday, high level then eventually mid clouds will be thickening
from southwest to northeast, as stronger warm advection shifts into
the mid Mississippi Valley and southern/eastern Great Lakes. There
is excellent model agreement that any precipitation will holds off,
thanks to plenty of dry air below 700 mb.

Thursday night, a surface low will push from the mid Mississippi
Valley up into the Ohio Valley. Precipiation will blossom across the
region from west to east within increasing warm and moist advection.
Precipitation initially will start as all rain. Precipitation should
stay all rain in the west, but begin to change back over to snow
east of the Finger lakes as we move through Thursday night. Small
accumulations look feasible.


The pattern will become more active again by the end of the week
after a few dry days. A mid level closed low will meander across the
Four Corners region through Tuesday, then eject ENE across the
southern Plains to the Ohio Valley by Friday. The 12Z guidance has
trended a little southward with the track of the ensuing surface
low, but still more than close enough to bring another period of wet
weather to our region. Rain will begin to overspread Western NY
Thursday night, then spread across the rest of the area by Friday
morning as the closed low and surface low move into the Ohio Valley
and spread large scale ascent and moisture transport into our
region. Periods of rain then continue Friday and Friday night as the
system moves slowly towards the Mid Atlantic states. With the
farther south low track, the rain may start as a period of wet snow
across the North Country late Thursday night and Friday morning, but
this will not amount to much with an eventual change to rain
expected even there.

This system will slowly pull out next weekend, with a few scattered
showers lingering into Saturday as the trough and surface low move
off the east coast, with northwest flow and wrap around moisture
hanging back across the Lower Great Lakes. Moisture and rain chances
should diminish by Sunday as the trough moves well off the eastern
seaboard. The 12Z GFS develops a few showers of rain and wet snow
later Saturday night and Sunday with a weak northern stream trough,
but for now favored the drier ECMWF solution for this time period.

Temperatures will likely run near to slightly above average through
the period, with highs generally in the upper 40s to lower 50s and
lows in the 30s.


For the 06Z TAFS flight conditions that are generally VFR across the
region will likely lower to IFR across all 5 TAF sites as a moist
airmass remains along with light winds.

A weak frontal boundary will cross the region between 09Z and 15Z,
and along this frontal boundary will be chances for showers, along
with areas of fog. Visibilities will likely lower to IFR or lower
for a 2 to 4 hour period around sunrise, with a then northern flow
maintaining IFR ceilings for a period of time into the afternoon
hours. These IFR CIGS will likely remain longest across the So.
Tier, including the KJHW terminal.

By tonight an area of high pressure will be funneling much drier air
across the region. This will thin the low stratus, that may remain
MVFR (IFR So. Tier) through Tuesday night.


Wednesday and into Thursday...VFR.

Thursday night into Saturday...MVFR/IFR with occasional rain showers.


A weak to modest pressure gradient across the Lower Lakes
Region will lead to continued relatively light winds and minimal
waves right through Tuesday. A somewhat stronger northerly flow
will then follow Tuesday night through Wednesday as strong
Canadian high pressure builds across the Great Lakes...however
winds and waves are expected to remain below advisory levels.





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