Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Buffalo New York
1210 PM EDT Friday Jul 25 2014
high pressure will remain in place over the Ohio Valley and provide
another day of abundant sunshine with cool morning temperatures
giving way to a warm afternoon. A weak warm front will cross the
region Saturday and produce increasing clouds later tonight and a
chance of a few showers and thunderstorms on Saturday. Unsettled
weather will then continue through early next week as several waves
of low pressure cross the Great Lakes region.
Near term /through tonight/...
high pressure will keep conditions quiet this afternoon with an
abundance of sunshine filtering through a thin layer of smoke in the
middle-upper levels of the atmosphere...smoke originating from wildfires
in northwestern Canada. Visible satellite imagery indicates
strato-cumulus blossoming along/ahead of lake breeze boundaries in
western New York and to a lesser extent east of Lake Ontario...however
given the Stout cap in place around 850mb...these clouds will remain
harmless and will move inland this afternoon with the lake breeze.
Expect temperatures to top out in the middle to upper 70s with the
warmest areas being in the Genesee Valley and along the Lake
Ontario plain where downsloping southwesterly flow will enhance
afternoon readings by a degree or two. Coolest spots will be in
the higher elevations of the southern tier and the Tug Hill where
lower 70s are expected.
The lake breeze will quickly fizzle after sunset and it will be one
more quiet night for the region as the high begins to slide off to
the east. Increasing return flow will result in a warmer night than
last night with lows in the upper 50s to lower 60s...with lower 50s
in the southern tier and inland north country. Warm advection aloft
will bring middle-level cloudiness in from the west after midnight in
advance of an approaching warm front that may bring a few sprinkles
across extreme western New York towards dawn.
Short term /Saturday through Sunday night/...
Saturday will begin what will be a rather unsettled stretch of
weather for the northeastern US. The weekend does not look like a
total washout by any means...with some dry time built in. One
positive is that temperatures will be close to seasonal averages
with high temperatures running from the middle 70s to the lower 80s
across the region.
The details...Saturday morning a warm frontal boundary will be
located just to the west of New York state. Expect a good deal of
cloud cover to be in place...with possibly a few showers across
western areas. The warm front will be very slow to cross the
region...possibly only making it to central New York by late in the
day. That will keep the chance for showers and possibly a
thunderstorm in for the entire day...with the best chances for
measurable rainfall across western portions of New York Saturday
afternoon. High temperatures will range from the middle and upper 70s
to the lower 80s across the region. Dew point temperatures will be
on the increase as the day wears on...so it will feel a bit more
humid as well. Saturday night low pressure will pass north of the
New York and finally push the warm front east of the area early in
the night...only to be followed by cold front that will swing
through the region very late Saturday night into Sunday morning.
This will keep at least the chance for showers and thunderstorms in
the forecast. Low temperatures will remain on the warmer side with
lows ranging from the lower to upper 60s across the region.
Sunday it looks like we will be sandwiched between two low pressure
systems...one moving away from the area into New England and another
moving southeast out of the upper Great Lakes into the Ohio Valley.
There will be a boundary stretching between these two areas of low
pressure somewhere in the vicinity of New York state. Latest model
consensus shows that a good deal of the day may be dry. Severe
weather threat still looks low at this time as best shear and
instability parameters still remain to the south and southwest of
the area. This will have to monitored closely as the location of the
frontal boundary and any shift northward of the aforementioned
severe parameters could change things. High temperatures Sunday will
again range from the middle and upper 70s to around 80. Sunday night
the main shortwave aloft will drop into the base of the longwave
trough. The combination of the approaching shortwave and surface low
pressure passing just to the south of New York will mean increased
chances for showers and thunderstorms later in the night. Lows will
generally be in the lower 60s for most areas.
Long term /Monday through Thursday/...
an unsettled pattern will persist into next week with a broad 500mb
trough across the eastern states. This will keep a threat of showers
in the forecast with below average temperatures. Monday has the best
potential for showers with even thunderstorms possible as a sharp
shortwave trough and surface low which are mentioned in the short
term discussion passes across the lower Great Lakes. The extent of
showers and possible thunderstorms will depend on the exact timing
of when this system will cross New York. The 12z GFS is a bit faster
than the 12z European model (ecmwf). While most of next week will remain dry and cool
the instability brought on by the lower heights and colder air aloft
will be enough to keep a chance of diurnal showers on Tuesday
through Thursday. Lake effect rain showers may even be possible with
850mb temperatures dropping below +10c.
Cooling temperatures aloft brought on by -3sd 500mb heights will
bring below normal temperatures Monday through Thursday. Highs will
average 5 to 10 degrees below normal late July averages. High
temperatures on Tuesday will be the coolest of the next 7 days
topping out in the upper 60s to low 70s. A Pacific sourced airmass
will keep dewpoints in the 50s so overnight temperatures will only run a
few degrees below average.
Aviation /16z Friday through Tuesday/...
VFR conditions will prevail through the forecast period as high
pressure crests over the region. Middle level ceilings will move into the
forecast area towards the end of the forecast period...in the 06-12z
period in advance of an approaching warm front that will bring
showers and thunderstorms later on Saturday.
Saturday through Monday...VFR much of the time with showers and
thunderstorms likely a times along with associated brief MVFR/IFR.
Tuesday...mainly VFR with a chance of showers.
southwest winds will increase into the 10-15 knot range from midday
through afternoon on Lake Erie and the east end of Lake Ontario.
This will produce some choppy conditions on both lakes for the
afternoon...but conditions are expected to remain below Small Craft
Advisory criteria. Expect more of the same through Saturday with
winds occasionally increasing into the 10-15 knot range will choppy
conditions at times.