Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Buffalo New York
1042 am EDT Friday Jul 11 2014
gorgeous weather will remain in place across western and north
central New York today as high pressure over the region will supply
US with ample sunshine and comfortable temperatures. As the high
moves off the coast on Saturday...it will become warmer and
noticeably more humid but fair weather should prevail. Deteriorating
conditions can then be expected for the second half of the weekend
as a frontal system will offer up the likelihood of thunderstorms.
Near term /through tonight/...
high pressure centered over our region will gradually push east
this afternoon and tonight. This will keep fair comfortable weather
in place with mainly clear skies and light winds through tonight.
River Valley fog will develop again tonight across the southern tier.
High temperatures this afternoon will be about 5 degrees higher than
those from yesterday...peaking to within a couple degrees of 80 in
most areas. Likewise...tonight will be warmer than the past few as
the Mercury will only settle to between 55 and 60 for the bulk of
Short term /Saturday through Sunday night/...
on Saturday...surface-based ridging initially anchored along the
Atlantic coastline will slowly drift offshore. On its backside...a
modest southwesterly return flow will set up at the low levels...and
will help advect somewhat warmer and more moist air into New York
state. Coupled with diurnal heating and the passage of a weak middle
level shortwave...this increase in moisture may lead to some
isolated to widely scattered convection from The Finger lakes
eastward into central New York during the afternoon...for which some
slight chance probability of precipitation will remain in play. Otherwise...expect a dry and
warmer day with 850 mb temperatures and a decent amount of sunshine
supporting widespread highs in the lower to middle 80s...with the
warmest readings found across interior sections of the Genesee
Valley and Finger Lakes.
Saturday night...any leftover isolated convection across The Finger
lakes and central New York should quickly diminish with the loss of
heating Saturday evening...with dry conditions otherwise prevailing
through the first half of the night. Overnight...an approaching
shortwave and attendant warm front will spread increasing amounts of
lift and moisture into the area along with some modest elevated
instability...which will lead to shower and thunderstorm chances
increasing from west to east. With respect to temperatures...expect a much
warmer and moderately humid night compared to the previous few
nights given the presence of a strengthening southerly low level
flow/continued warm air advection regime...with lows ranging from
the lower 60s across far interior sections of the southern tier and
north country to around 70 across the lake plains of far western New
During the course of Sunday...the aforementioned shortwave and warm
frontal boundary will push east across our region...along with an
attendant 40-50 knots low level jet. These features will provide a
decent amount of synoptic-scale forcing...which will act to lift an
increasingly moist (pwats of 1.5 to 2 inches) and somewhat unstable
airmass to produce a likelihood of showers and thunderstorms across
the entire area. With both this and continued timing differences
amongst the various models in mind...have continued with broadbrush
likely probability of precipitation for much of the day. Given the very moist airmass...the
greatest potential threat from sunday's convection appears to be
locally heavy rainfall. At this point...the threat for severe storms
appears to be much lower given current projections of only weak to
modest instability levels...though is certainly not none either with
a moderately strong flow present in the lower to middle levels of the
The showers/storms should then generally diminish in coverage
following the passage of the warm front Sunday night...though have
left at least some low-middle chance range probability of precipitation in play overnight with
a general cyclonic flow at all levels remaining in place.
Temperature and humidity-wise...expect warm and fairly humid
conditions during the latter half of the short term period with
highs ranging in the upper 70s to lower 80s Sunday...lows falling to
the middle to upper 60s Sunday night...and dewpoints generally rising
into the middle and upper 60s.
Long term /Monday through Thursday/...
in the longer term portion of the forecast...the medium range
guidance remains in strong agreement on anomalously deep upper-level
troughing digging from the northern plains southeastward across the
Great Lakes and northeast through the middle of next week. This will
result in continued unsettled weather through at least Tuesday...
along with a noticeable cooling trend through Wednesday as the
attendant cool pool aloft drops southeastward across the Great
With respect to precipitation chances...through Tuesday the best
chances for showers/storms will be tied to the passage of embedded
shortwave features circulating through the developing large-scale
trough...which much like last week will be accompanied at the
surface by one or more cold frontal segments. With the exact timing
of these features still remaining in very much in question this far
in advance...have elected to keep broadbrush chance probability of precipitation in place
through Tuesday at the present time. Along with the general
unsettled weather...there will be at least some potential for
strong to severe storms right through Tuesday with increasing
amounts of shear and dynamics coming into play as the upper level
trough approaches...with this ultimately dependent upon the amount
of instability that can be realized.
By Wednesday...the various guidance packages are in decent agreement
that the main cold frontal boundary will have slid east of the area
and into New England...with a swath of much drier air spreading
across our area in between the departed front...and the main upper
level trough axis/area of wraparound moisture hanging back over the
central Great Lakes. This should lead to mainly dry weather...
although with a much cooler airmass in place aloft a stray shower or
two still cannot be totally ruled out Wednesday and Wednesday night.
On Thursday...the main upper level trough axis will cross the region
along with an associated modest increase in moisture...leading to
renewed chances for scattered showers and perhaps some isolated
thunderstorms...all of which have been covered with some lower-end
chance probability of precipitation.
Temperature-wise...850 mb temperatures ranging from +14c to +16c at the
start of the period may drop as low as +7c/+8c by the middle of next
week. Should these readings actually come to fruition...highs in the
lower to middle 80s on Monday will likely drop back to the upper 60s
and lower 70s by midweek...with nighttime lows correspondingly also
falling some ten degrees.
Aviation /15z Friday through Tuesday/...
high pressure overhead will keep fair VFR weather conditions in
place through at least Saturday. The lone fly in the ointment may be
a few hours of IFR/MVFR conditions from radiation valley fog at kjhw
again late tonight. Surface winds will be under 10 knots through tonight.
Sunday through Tuesday...mainly VFR with a chance of showers and
thunderstorms and associated brief MVFR/IFR. Greatest coverage of
thunderstorms will be on Sunday and again Monday night/Tuesday with
a passage of a cold front.
Wednesday...mainly VFR with scattered showers and MVFR level ceilings.
fair weather with light winds will persist across the lower Great
Lakes and St Lawrence Valley through at least Saturday...as high
pressure will slowly drift east across our region.
Recreational boaters should take advantage of the current spell of
fair weather...as the pleasant conditions will deteriorate Saturday
night and particularly on Sunday as the next frontal system will
take aim on the region. Showers and thunderstorms will become likely