Area forecast discussion
National Weather Service Buffalo New York
1041 am EDT Sat may 25 2013
Synopsis...
Canadian high pressure building across the Great Lakes will bring
mainly dry and cool conditions this weekend. Temperatures will
rebound back to above average next week.
&&
Near term /through tonight/...
water vapor imagery this morning showing a deep trough along the
East Coast in the process of transitioning into a well defined
cutoff low. At the surface...this is aiding in the development of a
rare late may Nor'easter. The precipitation shield is backing into
eastern Lewis County now...and will back west just a little further
to near the Black River valley today as a persistent axis of
deformation in the 900-700mb layer backs west slightly. Expect a
chilly rain today for these areas...with thicker middle level cloud
extending back across Jefferson and Lewis counties.
Farther west...it will remain dry today although the very chilly air
aloft combined with the strong late may sun angle and some remaining
low level moisture will result in self-destruct sunshine across
areas inland from the lakes. This will produce mostly cloudy skies
across the higher terrain of the southern tier and Finger Lakes. A
northwest flow off the lakes and strong differential heating should
result in stable lake shadows this afternoon...with much more
sunshine within 10-20 miles of the lakes from Wayne County westward.
Temperatures will be below normal again today...with highs likely to
struggle to reach the upper 50s...even in areas with more sunshine.
East of Lake Ontario...expect highs will remain in the middle to upper
40s across higher terrain with thick cloud cover. Modest northwest winds of
15 to 20 miles per hour will make it feel even a bit cooler.
Expect tonight to be similar to last night...with slightly less
cloud cover but slightly warmer 850mb temperatures the result
will likely be quite similar. Because of this...have issued a
freeze watch for tonight for western portions of the southern
tier. Elsewhere...it will be chilly...but for the most part
temperatures should remain above freezing in the upper 30s to
lower 40s.
&&
Short term /Sunday through Monday night/...
the deep low that will be centered over New England Sunday morning
will lift slowly to the northeast and settle over the Canadian
Maritimes on Monday. The far western edge of the clouds that are
associated with this system may linger over eastern Lewis County
Sunday...but the bulk of any precipitation should stay mainly to the east.
Otherwise...expect sunny skies across the rest of the area on Sunday
..but temperatures will remain below average due to the cool
northwest flow circulating around the persistent low.
As the low pulls away Sunday night...clear skies and diminishing
winds will set the stage for another chilly night. Temperatures
close to the lakes will dip into the lower 40s...but inland
locations will likely see readings cooling into the 30s...especially
across the southern tier where areas of frost and/or a freeze are
possible.
On Monday the surface high will crest over New York state and bring
more sunshine and seasonable temperatures to our area. Dry
conditions will continue Monday night with temperatures
dropping back into the 40s.
&&
Long term /Tuesday through Friday/...
a return to well above average temperatures will characterize this
period as an upper ridge builds over the eastern half of the nation
in response to a deepening trough out west.
At the surface...there is still some disagreement among the models
regarding the timing of a warm front that will be lifting north from
the Ohio Valley. The NAM still lifts the front to the north faster
and brings showers into western New York by Tuesday morning...while
the GFS and European model (ecmwf) hold the precipitation off until late Tuesday and Tuesday
night. Based on these trends...will maintain continuity and follow
the slower GFS/European model (ecmwf) solutions.
After the warm front passes north of the state on Wednesday
..humidity will begin to build...And temperatures each day will
likely warm by a couple of degrees. By Friday afternoon highs will
be well into the 80s across the region. The building ridge over the
region Thursday and Friday will likely cap afternoon
convection...and thus we will maintain a dry forecast for now.
However...will have to keep an eye on the possibility that a back
door cold front may drop south across the area late Thursday...as
depicted by the European model (ecmwf).
&&
Aviation /15z Saturday through Wednesday/...
low pressure will close off in the upper levels across New
England...with our region on the western periphery of this system.
This will keep a solid middle level deck over the Eastern Lake Ontario
region today with some light rain along and east of the Black River
valley. Elsewhere the cold air aloft combined with strong late may
sun will produce plenty of cumulus and stratocumulus across higher
terrain with ceilings in the 4-5k range. Stable lake shadows will keep
skies more clear within 10-20 miles of the lakeshores from kroc
westward.
Tonight the clouds across western New York will mostly dissipate with the
loss of daytime heating...although lake effect clouds may try to
re-generate overnight. East of Lake Ontario clouds will linger at
Art which is closest to the low but VFR should prevail.
Outlook...
Sunday through Tuesday...VFR.
Wednesday...mainly VFR with a chance of showers and thunderstorms.
&&
Marine...
low pressure near Cape Cod will result in a persistent northwest flow
across the waters for the weekend. Given the modest pressure
gradient...this will result in conditions marginal to Small Craft Advisory for most
of the waters...with winds generally in the 10 to 20 knot range.
Surface temperatures cooler than the water tonight has helped aid
mixing...and because of this the small craft headlines have been
extended a bit on Lake Erie.
Winds will diminish this afternoon...but may increase modestly
tonight. It is possible more headlines will be needed on eastern
portions of Lake Ontario tonight. After this...the ridge will build
across the waters...with diminishing winds on Sunday Onward.
&&
Buf watches/warnings/advisories...
New York...freeze watch from late tonight through Sunday morning for
nyz019>021.
Marine...Small Craft Advisory until 2 PM EDT Sunday for loz042>045.
&&
$$
Synopsis...apffel/tma
near term...apffel/Hitchcock
short term...tjp
long term...tjp
aviation...apffel/Hitchcock
marine...apffel/tjp
