Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Binghamton New York
814 PM EDT sun Mar 29 2015
brief high pressure will give way to a frontal system pushing snow
and rain showers into the forecast area tonight and Monday.
Following a brief break Monday night, a clipper system diving south
and east will bring a chance of more rain and snow Tuesday.
Near term /through Monday/...
8 PM update...
high thin clouds now overspreading the area ahead of frontal system.
Adjusted onset of probability of precipitation slower by 1-2 hours later tonight...based
on upstream observation and high res model trends...otherwise little
change. One thing to note is almost immediately after top-down
moistening tonight...wave passage removes deeper moisture and thus
it turns out that almost entire saturated layer is warmer than
dendritic growth temperatures. Portion of column with best Omega /lift/
will only be minus-2 to minus-6 celsius. So while northern Oneida
County may manage a quick 1-3 inches snow accumulation at higher
elevations late tonight into Monday morning due to the help of
upsloping /and slightly thicker saturated layer there/...agree
with previous forecast of very light coating of under an inch
elsewhere. Some lower elevations will have no accumulation at all.
Regardless...it will melt during the day with lingering spotty showers
also changing to rain.
high pressure is cresting over the area this afternoon with
sunshine and temperatures in the 30s. However a fairly quick
moving frontal system will bring increasing clouds by later this
evening with a shot of some rain and snow arriving overnight from
west to east...likely beginning around or just after midnight.
Temperatures will drop off into the upper 20s to low 30s this
evening and then hold fairly steady or even rise overnight across
the lake plain as the system brings in a milder SW flow. We
continue to depict snow showers in the grids with a rain/snow mix
over the lake plain where temperatures will be just above
For Monday, the initial shot of precipitation associated with the surface
occlusion pushes off to the east however expect snow/rain showers
to linger due to the upper trough associated with the system. As
is typical in these scenarios, showers will be most prevalent
over central New York portion of the County Warning Area. Also, as temperatures Monday moderate
into the upper 30s north and 40s south by the afternoon precipitation will
become mainly rain showers. In terms of any snow accumulation by
this time, we are not expecting much for most areas...generally a
light coating to just under an inch...heaviest along and east of
the I-81 corridor in central New York. The exception will be northern
Oneida in the southern Tug Hill where 1 to 3 inches will be possible
by Monday afternoon. Finally, expect strong gusty winds by Monday
afternoon out of the west with gusts of 25 to 30 miles per hour.
Short term /Monday night through Wednesday/...
snow/rain showers diminish Monday night with a glancing shot of
colder air moving back in. Lows by early Tuesday will generally be
in the 20s to around 30.
The forecast becomes tricky for Tuesday as there is considerable
model disagreement on the track of a clipper system that will be
diving southeast toward the area. The GFS and the European model (ecmwf) keep this
low and most of its precipitation to our south while the NAM and Gem global
track the system farther north and bring the area a shot of more
significant precipitation by Tuesday afternoon into the evening. The
additional complicating factor will be the time of year and
marginal temperatures. If the more northern track were to verify, the
potential exists for accumulating wet snow over parts of NE PA into
the southern tier by late Tuesday...especially over the higher
terrain. However since confidence is still low at this time we did
not make many changes to the previous forecast and maintain chance
probability of precipitation for a rain/snow mix for Tuesday. In any event, clipper system
will move off to the east by Wednesday with high pressure bringing
fair but cool conditions Wednesday with highs generally ranging
from the middle 30s north to middle 4os south.
Long term /Wednesday night through Sunday/...
low confidence extended forecast due to significant model differences
and poor run to run consistency. Followed wpc guidance which is a
blend of the ecens mean and naefs mean. In general a warming trend
is expected as upper level flow across the Continental U.S. Becomes more
Wednesday night looks fair as surface high pressure resides off the New Jersey coast and
a complex system moves into the upper Great Lakes. Thursday
through Friday night will advertise high chance probability of precipitation for rain showers
as a warm front followed by the trailing cold front crosses the
northeast then a secondary wave develops along this boundary and
finally moves off the coast Saturday morning. During this period
the models show significant differences on the timing of fronts
and development of the secondary low. Saturday through Sunday will
be a return to slightly cooler weather and mixed rain/snow showers
although fairly minor.
Aviation /00z Monday through Friday/...
high thin clouds around 15 kft above ground level are already overspreading the
area...ahead of an upper level trough and surface occluded front
which will cross the terminals late tonight into Monday morning.
Winds generally south-southeast to south-southwest 8-12 kts overnight which is not very
conducive to IFR due to downsloping for most terminals...but MVFR
ceiling can be expected to develop as well as -shsn /only brief flurry
or sprinkle for kavp/. This occurs as wave passes 05z west to 10z
east. At this time only figuring MVFR restrictions...except some
IFR visible 07z-10z for krme due to localized upslope enhancement and
thicker saturated layer there as wave passes. One other note for
krme...localized southeast wind at surface will be in opposition to SW
jet at 40 kts around 2 kft above ground level...which will pose low level wind shear conditions
there 07z-12z. Other terminals not expected to quite meet low level wind shear
thresholds. Behind wave 10-15z...wind will veer SW to west and become
gusty during the daytime hours /gusts 22-28 kts/. Lingering spotty
-shsn will change to -shra with ceilings gradually lifting to higher
end MVFR/low end VFR. Best coverage of the light scattered showers
15z Onward will be ksyr-krme-kbgm-kith.
Monday night through Tuesday night...occasional minor restrictions in
rain/snow as weak waves move through.
Thursday night through Friday...possible restrictions in rain showers.