Scientific Forecaster Discussion
fxus61 kbgm 231603
Area forecast discussion
National Weather Service Binghamton New York
1103 am EST Thu Feb 23 2017
a warm southwest flow will keep temperatures above normal through
Saturday. A weak front will bring isolated rain showers today, and
a warm front will allow scattered rain showers and a few storms
Friday. A stronger system with widespread rain and a chance of
thunder is expected Saturday. Temperatures will be cooler Sunday
and Monday with scattered snow showers.
Near term /through tonight/...
Main concerns in the near term remain focused around the weak front
moving through today with isolated/scattered light rain
showers...the next round of scattered rain showers and a few weak
thunderstorms as well Friday morning...and the much above average
temperatures today and Friday.
Upper level trough moving into the wrn Great Lakes this morning
combined with a surface low over nrn Lake Huron and a trailing cold
front into the mid MS valley region will sweep to the E/NE today.
The front will drag across New York/PA as the upper forcing and surface
low lift into Quebec. A limited amount of deep layer moisture
relative to the warm air mass should keep the overall coverage
and intensity of any rain showers that do develop to a minimum.
Much of the region will remain in a weak warm air advection regime
today which will act to deepen the boundary layer and promote
mixing. Stronger winds aloft will be able to mix down to the
surface...so gusts around 15 to 25 mph today area possible. Cloud
cover may be challenging today, latest visible satellite is
showing clouds at along the front will stream over the region
this morning with low strato cumulus persisting. So have
slightly increased clouds in the north. With enough mixing
the sun should re- appear in the afternoon before a more solid
deck of clouds arrive ahead of the next system before sunset.
With the additional sun possible today, think there will be more
radiational contribution to the afternoon highs. So, have
increased temperatures a few degrees...with highs generally
topping out in the lower to mid 60s.
As mentioned above, the next system begins to move in this evening
and tonight in the form of a warm front along the leading edge of a
deepening low pressure system sliding into the srn Great Lakes. The
air mass along and south of this warm front will be quite unstable
for this time of year, and also be rather moist as well. Around 500-
1000 j/kg of bl cape and steep low level lapse rates will combine
with pwats over 1 inch and create favorable conditions for
convective development. So, have kept with rain showers and a chance
of thunderstorms...mainly from N-central PA into The Finger lakes
and over to the Mohawk Valley, although the air mass everywhere will
be unstable, the best forcing is expected in this area. Rainfall
amounts will be generally less than a quarter of an inch. Very
isolated locations that experience downpours may see a bit more.
The other story Friday will be the continued warmth. Morning low
temperatures Friday are expected to only drop into the 40s. Some
locations may not drop below 50. The warmer the temps are
tonight...the warmer they will be on Friday. Afternoon highs
Friday are expected be even warmer than today. Highs will top out
in the mid to upper 60s...near 70 in some locations.
There will likely be records broken today, tonight and/or tomorrow
in some locations. Check out the list of records below in the
Short term /Friday through Friday night/...
11 am update...
there are two main concerns this period. One is combined
snowmelt and quick period of heavier showers Saturday which
could lead to minor flood problems for some parts of the area.
Please read the hydrology section below for more specifics on
this potential. The second issue is possible strong gusty winds
within the squally line of showers-embedded thunder along the
powerful cold front Saturday afternoon-evening.
Friday night through Saturday morning we will be deep within
anomalous warm sector resulting in temperatures holding up in the
50s all night followed by upper 50s-lower 60s early to mid
Saturday. Dewpoints themselves will be in the lower 50s which no
doubt will feel strangely humid. Pressure gradient will also
greatly steepen Friday night-early Saturday ahead of the cold
front. The elevated dewpoints and increasing southerly wind will
be quick to melt almost all remaining pockets of snow.
Strong cold front with ample forcing and right entrance region of
jet will combine to bring a frontal line of heavier showers and
embedded thunderstorms along the front, in the abnormally warm
and humid airmass. It will be breezy, but synoptically speaking,
this system does not meet thresholds of local studies for an
organized stronger wind event. However, convectively, we do indeed
have potential for strong winds. Ahead of the front, from just a
few thousand feet above ground level all the way up to 6 km winds
will be ripping out of the south-southwest 50-plus knots. Behind
the front, boundary layer winds will veer westerly at lesser
speeds. The big question is if the pre-frontal and Post-frontal
wind fields will overlap enough for the line of showers-embedded
thunder to harness stronger winds and mix them down. At this point
we can expect that the convection will be quite gusty and hit
abruptly as it across the area Saturday afternoon-evening; the
only question is will it be enough for pockets of damaging wind.
The Storm Prediction Center has included a portion of our area as
a marginal risk for severe thunderstorms saturday; meaning there
is the potential for isolated severe thunderstorms.
Though we are advertising an areal average of 5 to 9 tenths of an
inch of rain, models depict a ribbon of precipitable water in
excess of an inch along the front. This is about three Standard
deviations above normal, and likewise for the southerly magnitude
of 850mb winds, so we will need to watch for downpours and
potential for localized rain amounts beyond an inch.
Long term /Saturday through Wednesday/...
415 am update...
forecast adjusted towards latest multi-model blend with little
change overall. However, one thing that has become apparent is
that the cold air advection Saturday evening will be very quick.
There is some potential of flash freezing of wet roadways Saturday
night, if breezy winds do not manage to dry them off first between
the heavier batch of rain directly along the front and the time
temperatures actually reach 32 degrees. Higher elevations will be
more prone to this occurring.
strong upper wave will take on negative tilt while surging
through the region Saturday night, bringing abrupt and gusty cold
air advection while changing lingering rain showers over to snow
showers but with only nominal slushy accumulations mainly in
central New York.
Sunday through Monday will be a temporary return to chilly near
normal temperatures. Lake effect snow showers will occur in parts
of central New York. Also, while the 12z GFS model actually
depicts our area on the north side of a wave which would result in
an accumulating snow Monday, the European model (ecmwf) and gemglobal models do
not so for now we are only maintaining slight/low chance of snow.
Overall west-southwest flow will continue, and thus the cool air
will be unable to manage a longer stay. We get back into warmer-
than-normal temperatures into midweek along with rain again
becoming the primary precipitation type to accompany any systems.
Aviation /16z Thursday through Monday/...
visibilities and ceilings at kelm continue to improve this morning
as a layer of mid/high clouds move in from the west. Otherwise
still expecting VFR/unrestricted conditions through at least 00z
this evening. A few unrestricted rain showers are possible today,
but uncertainty continues to be high enough to not include in
latest 12z tafs. Ceilings become MVFR this evening and drop into
the fuel alternate required category later tonight along with the
potential for MVFR vsbys in -ra/br when the warm front lifts north
through the region.
Winds will increase out of the south/SW later this morning and
persist through the afternoon. Expect sustained winds around 10 kt
and gusts up to 20 kt.
Winds diminish this evening as a layer of low level moisture rolls
in and lower ceilings develop...especially over central New York.
Friday...low ceilings Friday morning becoming mainly VFR by the
Saturday...restrictions in rain likely associated with a frontal
Sunday...possible restrictions from lake effect snow showers at ksyr-
krme, with mainly VFR elsewhere.
Monday...possible restrictions in light rain or snow.