Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 180231

Area Forecast Discussion
National Weather Service Buffalo NY
931 PM EST Fri Feb 17 2017

High pressure will generally provide our region with fair weather
through the weekend...though some pockets of low clouds and fog cannot
be ruled out. Meanwhile temperatures will rise to well above normal
levels on Saturday...with warmer than average readings then expected
to continue right through the upcoming work week.


As of this writing...mid and high level clouds continue to slide
southeastward across New York State in advance of a surface warm
front. Expect these to persist through midnight...before largely
giving way to clearing skies from west to east overnight and early
Saturday morning following the passage of the warm front. With the
lower levels remaining rather precipitation will accompany
the warm frontal passage.

Following the passage of the warm front, low level warm air advection
will ramp up and support rising temperatures overnight...particularly
across far western New York. As surface dew points climb above freezing
late tonight and Saturday morning, snow melt and rising humidity values
may allow for some pockets of fog and low clouds to form...though
increasing low level mixing should help to keep any fog and/or low
cloud development to a minimum.

Saturday, very mild air will be sent into the region. Temperatures
at 850 mb nearing +10C, some 2 to 3 standard deviations above
normal, supporting high temperatures in the lower to mid 50s.
However, northeast of the lakes, including the Buffalo metro
area temperatures will be cooler due to the lake influence with
highs only in the mid to upper 40s. It will also be quite windy
across the lake plains Saturday afternoon, with gusts to 45 mph.


A shortwave will track across southern Quebec Sunday, which will
drag a weak, moisture-starved surface cold front across the region.
The result will make for Sunday and Monday being cooler than
Saturday, although still largely mild for the time of year. There
may be enough lingering moisture over the North Country to prompt an
isolated shower or two with some cloud cover. However, the rest of
the forecast area will see fair conditions and some sunshine for
Sunday into Monday. Temperature wise, we are looking at low to mid
40s Sunday, and ranging from the mid 30s in the North Country to the
mid 40s in WNY on Monday behind the shortwave. Both nights will
mainly be in the 20s to around 30 in the warmer lake plains.

A sharp ridge axis will quickly build across the area Monday night,
with the region getting into the southwesterly warm advective flow
during the day Tuesday. Temperatures will soar on Tuesday as 850 mb
temperatures climb to values in the 90+ percentile for this time of
year. High temperatures will likely push the mid 50s in the common
downslope locations of the Genesee Valley and northern Finger Lakes
(which also have little to no snow pack to contend with).
Southwesterly flow off Lake Erie will keep temperatures along the
shoreline and Buffalo metro area in check (upper 40s to around 50,
even cooler right along the lake shore). Cloud cover will also
thicken through the day as the next weather system moves into the
upper Great Lakes (more on that below).


The extended period of unseasonable warmth will continue to be the
main story in the long term portion of the forecast. Another very
active Pacific Jet will send multiple systems into the west coast
over the next week, with zonal flow flooding the central and eastern
portion of the nation with warm Pacific air.

Looking at the details, a weakening trough will cross the lower
Great Lakes Tuesday night. This feature will have enough moisture
and forcing to produce a few showers across the area. Any lingering
showers will end from west to east Wednesday morning as high
pressure builds back into the Ohio Valley. Mainly dry weather will
then continue Wednesday afternoon through Thursday, although a few
showers may clip the Saint Lawrence Valley as a weak frontal
boundary stalls just north of Lake Ontario.

A stronger mid level trough and associated surface low is then
forecast to move across the Upper Midwest Thursday night and reach
the Upper Great Lakes Friday. A broad warm advection regime will
develop ahead of this system and produce an increasing chance of
showers again by Friday.

Temperatures will run way above normal through the entire period,
with highs generally in the 50s each day with 40s North Country.
Lows will be in the lower to mid 40s across Western NY and mid 30s
for the North Country. These values are roughly 20 degrees above
average for late February.

Looking a little farther ahead, more seasonable late winter cold may
return by the second half of next weekend as a ridge builds along
the west coast and forces a longwave trough to develop over the
central and eastern United States.


Expect VFR conditions to largely prevail tonight as a warm front
crosses the region...with nothing more than a period of mid and high
clouds marking its approach and passage. Late tonight some isolated
pockets of low clouds and fog could form as surface dewpoints climb
in the wake of the warm front...however these should remain rather
minimal in extent due to strengthening low level winds/mixing. Speaking
of which...the strengthening low level flow will also likely lead to
the development of some low level wind shear across far western New
York overnight.

On Saturday...aside from some limited pockets of IFR/MVFR in morning
fog/low stratus...general VFR conditions will continue to prevail.
It will also become rather windy...with areas of LLWS diminishing
as stronger winds from aloft become partially mixed to the surface.
Expect all of the terminals to experience surface wind gusts to 30-35
knots by afternoon...with some gusts closer to 40 knots not out of
the question across portions of far western New York.

Saturday night...mainly VFR.
Sunday and Monday...VFR.
Tuesday and Wednesday...Chance showers. Mainly VFR with MVFR


Winds and waves will remain relatively minimal through most of tonight
as surface high pressure slides east into New England...and a surface
warm front crosses the Lower Great Lakes. Low pressure tracking north
of the region late tonight and Saturday will tighten the pressure
gradient and bring about at least some increase in winds...though
increasingly stable conditions due to strong warm advection should help
to keep winds and waves largely under advisory levels this weekend.





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