Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 232047

Area Forecast Discussion
National Weather Service Buffalo NY
447 PM EDT TUE AUG 23 2016

High pressure will slowly drift east and off the Mid Atlantic
coastline through midweek. This feature will provide our region with
fair and dry weather through midweek, with a developing
southwesterly flow of warmer air helping to drive temperatures back
to above normal. A weak cold front will then cross the region
Thursday with a few rounds of scattered showers and thunderstorms
before fair weather returns in time for the weekend.


Visible satellite imagery showing just a few fields of sct cumulus
late this afternoon from Rochester eastward into Central NY and the
North Country. Most of these cumulus will dissipate early this
evening as the boundary layer begins to stabilize near sunset,
leaving clear skies across most of the region.

Tonight and Wednesday surface high pressure will slowly drift east
to the Mid Atlantic coastline. This feature will maintain fair and
dry weather across our region. A few clouds may linger through the
first half of the night in the vicinity of Lake Ontario as model
guidance brings a small area of higher RH southward out of southern
Ontario, but any clouds that do move into the area will dissipate
overnight as ongoing subsidence beneath high pressure forces drying.
Lows tonight will then drop back into the mid 50s to lower
60s...with somewhat limited valley fog again forming across the
Western Southern Tier tonight.

Wednesday will be another mostly clear day across the region with a
few diurnal cumulus and some high thin clouds approaching western NY
late in the day. As high pressure slides further off the coast this
will allow a steady increase of heat and humidity in the southerly
return flow. 850 mb temperatures will surge to around +17/+18C,
bringing high temperatures mainly in the upper 80s, with some low
90s in the downslope regions of the Genesee valley and northern
Finger Lakes.


After a quiet first half of the week, unsettled weather will return
to Western and North-Central New York starting Wednesday night.
Models are continuing to come into better agreement on a vortmax,
currently visible on wv imagery over Arizona, lifting across the
Great Plains and to the Upper Great Lakes by Wednesday. While the
core of this system and bulk of the resultant convection looks to
pass to our north across Ontario province Wednesday night, the
attendant 500mb trough should clip our area, and this along with
ongoing theta-e advection should be enough to keep a chance of
showers and thunderstorms in the forecast.

Aforementioned theta-e advection will strengthen across the forecast
area on Thursday as warm and sticky GOMEX air flowing around the
periphery of the sub-tropical ridge parked over the Southeastern
U.S. makes its way across the Lower Great Lakes. The arrival of this
hot and humid air will set the stage for more widespread showers and
thunderstorms Thursday afternoon into Thursday evening, with pieces
of shortwave energy ejecting out of the Midwest acting as additional
triggers to convection, in addition to the usual array of lakebreeze
and local convergence boundaries. Given the very moist nature of this
airmass, featuring pwats approaching 2.0 inches, localized heavy
downpours will be a threat. This slug of moisture is currently
progged to pass through the area Thursday night into Friday morning,
with pops diminishing Friday morning as a cold front pushes through,
ushering in cooler and much drier air for the weekend...

Regarding temperatures, with the arrival of the previously discussed
GOMEX airmass, we will see the return of sultry, sticky nights to
the region Wednesday and Thursday night, with lows ranging from the
upper 60s to the lower 70s, with warmest areas along the lake plains
and the urban areas. Thursday will be the warmest day of the period,
with highs climbing into the upper 80s, before the arrival of cooler
and drier air from Canada brings more pleasant highs in the upper
70s to lower 80s on Friday.


Overall, the weekend looks to be relatively quiet as a broad surface
high centered over the Upper Great Lakes slides across the region
and then moves into New England by late Sunday. The only hiccup,
increasing moisture and southerly flow across the region ahead of
the next approaching storm system which brings a chance of a few
showers and thunderstorms late in the day Sunday and into Monday.
Otherwise, the weekend looks spectacular, especially Saturday where
highs will peak in the upper 70s to low 80s with low relative
humidity levels. On Sunday, it will be several degrees warmer with
highs in the low to mid 80s, but humidity levels will tick up a bit
making it feel a little bit uncomfortable but not unbearable.
Monday, as a weak shortwave passes by to the north of the Lower
Great Lakes its associated cold front is forecast to slowly sag
southward across the region and then stall across OH/PA. Look for a
chance of a few showers and thunderstorms on Monday but mainly
across the Southern Tier and Finger Lakes to Central New York.
Otherwise, right now temperature wise the rest of this period looks
mild with above normal highs with no sign of fall weather at all.


High pressure drifting from Maryland to the Mid Atlantic coastline
will continue to lead to predominantly VFR conditions across the
region. The only exception to this will be across the Southern
Tier...where valley fog will lead to some areas of IFR/LIFR
overnight tonight, although this may stay just east of JHW like last
night. Another fine flying day with VFR conditions is expected

Thursday...VFR with scattered showers and thunderstorms
becoming more numerous Thursday night...when some MVFR will also
become possible.
Friday thru Sunday...Mainly VFR.


High pressure will drift from Maryland off the Mid Atlantic
coastline through midweek...while maintaining light to modest winds
and lower waves.

Thursday and Thursday night a cold front will ease its way across the
Lower Lakes. This feature will bring some showers and thunderstorms
to the region...with freshening southwesterlies out in advance of the
front veering to westerly following its passage Thursday night...
then gradually diminishing on Friday as high pressure builds into
the region. Depending upon how much winds and waves increase...small
craft advisories may eventually be needed for some areas Thursday
and Thursday night.





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