Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 262345

Area Forecast Discussion
National Weather Service Buffalo NY
645 PM EST Sun Feb 26 2017

The weather will be mainly dry through Monday before a warm front
brings a few rain showers on Tuesday. An area of low pressure will
then move through the Great Lakes Wednesday with another period of
rain and gusty winds. Temperatures will warm to well above normal
again by Wednesday before winter cold returns late in the week.


Regional radars this evening display a few light flurries flying
across the interior North Country. Otherwise the region is dry with
passing clouds.

A warm front will lift across the Lower Great Lakes tonight, with an
increasing southwesterly mid-level flow. 12Z NAM/GFS guidance
increase 925mb winds to 50 kts for a few hours, but this should
struggle to mix to the surface given the warm air advection and
overnight timing. It still will get windy across the lake
plains, especially northeast of Lake Erie where gusts will
probably top 40 mph but stay below advisory criteria.

There will be limited radiational cooling tonight due to the
increasing winds. Expect lows only a few degrees cooler
than todays high temperatures.

Monday will be warmer with mainly fair weather with a mix of
sun and clouds underneath a weak ridge axis. Highs will be in
40s in most locations, probably reaching 50 across the lower
Genesee Valley and Finger Lakes regions. This will result in a
weak lake-breeze near the immediate lakeshores. A weak wave
will pass to the north, with some high resolution guidance
forecasting light QPF across the Eastern Lake Ontario region.
Showers will be light and unlikely to measure so limit POPs to
a slight chance.


A deepening west coast trough will promote slowly rising heights and
low amplitude ridging across the eastern states Monday night. Weak
isentropic lift will be in place ahead of a developing warm front
that will support mainly cloudy skies as weak synoptic forcing
should only provide for slight to low chances for some rain or
isolated snow showers. Light southerly flow and increasing cloud
cover will hold overnight temps a little warmer than Sunday night
with lows expected to range from the low to mid 30s.

On Tuesday, low pressure will begin strengthening over the Central
Plains as the western trough shifts across the Great Basin. A
strengthening low level jet east of the surface low should lift a
surface warm front across western and central New York through the
day. Have included likely pops for rain showers ahead of and along
this warm front which may include some isolated storms although weak
lapse rates and positive lifted indices do not support widespread
convection. The 12z GFS is about 6 hours quicker than the 12z EC so
there will likely be some adjustments to the timing of the front and
associated showers as model agreement increases. The warm front will
usher in a return to well above normal temperatures as we turn the
calender from February to March. Expect temperatures to warm into
the low to mid 50s across western NY with upper 40s to near 50 east
of Lake Ontario.

Tuesday night into Wednesday and Wednesday night models track the
deepening surface low across Wisconsin or Michigan then north of
Lake Huron into southwestern Quebec. In terms of precipitation,
model solutions are hinting at a prefrontal trough bringing a first
round of showers and possibly thunderstorms Wednesday morning
followed by another round along a strong cold front Wednesday
evening. Instability and shear parameters favor a High Shear/Low
CAPE setup with about 65kts of 0-6km bulk shear but surfaced based
CAPE less than 1000 j/kg. This environment would favor storms with
damaging winds so a mention of this will be added to the Hazardous
Weather Outlook. Temperatures will stay very mild with a possible
non-diurnal temperature curve Tuesday night. Low temperatures in the
mid to upper 40s will warm into the low to mid 50s by Wednesday
morning then push into the upper 50s to low 60s for highs during the
day ahead of the cold front.

There remains a threat of non-convective strong winds Wednesday
night in the wake of the strong cold front. The deepening storm
system will shift along a favorable track to our northwest with
winds from a lingering low level jet mixing down in steeping low
level lapse rates behind the front. The 12z EC shows the lingering
jet in the 50-60kt range while the 12z GFS shows the jet a little
weaker in the 40-50kt range. Potential impact tables from a local
research study link these parameters to either an Advisory type wind
event should the GFS verify or a limited extent High Wind event
should the EC verify. Will add mention of a potential for strong
winds into the Hazardous Weather Outlook for this risk as well.
Temperatures will sharply fall back into the upper 20s to low 30s
through Wednesday night returning our weather back to more wintry
pattern with chances for some rain showers changing to snow showers
through the night.


Winter conditions will return for the end of week into the weekend
as a deep progressive trough brings a surge of colder air across the
northeast CONUS. Weak shortwaves may affect the region in the
developing northwest mid/upper level flow. Confidence is getting
higher that enough cold air will slide into the area for increasing
northwest/west-northwest flow lake effect snows from late Thursday
into Friday night as 850 mb temperatures drop to around -18C by
Friday night. A stronger Pacific shortwave and surface low moving
into the upper Great lakes will bring increasing warm air advection
later Saturday and Sunday with precipitation chances diminishing
along with temperatures moderating into the 40s by Sunday.


For the 00Z TAFS VFR flight conditions will be predominate with
passing mid and high level clouds. Winds will become gusty tonight,
(into the 30 knot range across the lake plain) as a LLJ increases.
The strongest winds should remain aloft, with low level wind sheet
very limited, and not included in the TAFS.


Monday night...VFR.
Tuesday...VFR/MVFR with a chance of showers.
Wednesday...MVFR/IFR with periods of rain.
Thursday and Friday...Mainly VFR. A chance of snow showers.


A strong pressure gradient between high pressure centered over the
southeast states and low pressure over the Canadian Maritimes will
maintain moderate to strong winds on the Lower Great Lakes through
Monday morning with higher end Small Craft Advisory conditions.
Winds will diminish Monday afternoon as a ridge of high pressure
briefly builds into the Lower Great Lakes.

Stronger winds will return Wednesday night and Thursday in the wake
of a deepening storm over Quebec. Winds may approach gale force,
depending on how strong the system is.


The flood watch has been dropped since there is no additional
flooding expected outside of the existing river flood warnings.
Also, river forecasts for Boonville and Watertown were lowered
based on latest precipitation and runoff data. Crests are now
expected to be near flood stage at each forecast point.


MARINE...Small Craft Advisory until 1 PM EST Monday for LEZ040-041.
         Small Craft Advisory until 7 AM EST Monday for LEZ020.
         Small Craft Advisory until 4 PM EST Monday for
         Small Craft Advisory until 1 PM EST Monday for LOZ042.



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