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Area forecast discussion 
National Weather Service Binghamton New York
1022 am EDT Sat Oct 25 2014

Synopsis...
a weak high pressure ridge will initially keep things dry and mild
across central New York and northeast Pennsylvania today...but a
cold front will sweep across late afternoon through evening with
clouds and scattered showers. The best chance for showers will be
north of the twin tiers. Behind the front it will be blustery and
cooler Sunday...with lake effect rain showers mainly in central
New York. Dry Monday with another passing high pressure ridge.

&&

Near term /through tonight/...
10 am update...
surface low sitting up around Hudson Bay has brought a surface warm front into
western New York with cold front entering into western Michigan. Strong shortwave is now
crossing north of Lake Huron and has spread line of showers along
the Ontario/Quebec border. Lightning strikes were noted about 6
hours ago but none since. Storm Prediction Center mesoanalysis Page indicated impressive
middle-level lapse rates >7 c/km with cooling temperatures associated with shortwave.

Current model projections showing these favorable lapse rates will
remain up toward the dacks this evening and with k-indices prognosticated to be 24
at the most, am not feeling confident of any thunder potential at
all for late afternoon/evening hours and have rmvd mention from grids. Only
caveat will be h2 speed maximum diving into central PA this evening lvg northern
zones in favorable location for lift.

Have tweaked hrly T/dew point values to reflect current trends but no other
changes needed at this time.

Previous discussions below...

620 am update...
made some tweaks to sky grids with quicker advancement of clouds
across western to central zones ongoing...also accordingly adjusted
temperature grids. All else on track.

Previous discussion...
main feature of interest in the near term will be a pre- frontal
trough sweeping through with scattered showers and an isolated
thunderstorm late afternoon through evening /mainly north/ on an
otherwise mainly dry period...followed by cold front tonight.

A weak ridge of high pressure is currently passing through the
region...and it is not exactly the cleanest considering the
moisture that is trapped under the subsidence inversion with
strong warm air advection aloft. A layer of clouds at 4-6 kft above ground level
throughout West New York/northwest PA is now spreading east including Syracuse to
Penn Yan so far...en Route to most of our area later this morning
those clouds are associated with a warm front. So perhaps more
clouds than originally figured for today...yet with warm frontal
passage bringing in southwest flow ahead of the incoming trough
/with gusts into 15-25 miles per hour range this afternoon/...we should still
see some sun mixing in as well during the day as we get briefly
into the warm sector of this system. This will realize highs in
the upper 50s to middle 60s...about 5 to 7 degrees above climatology.

Models are well agreed on pre-frontal trough then passing through
from 4pm west-northwest to 9pm east-northeast. It will do so with limited shallow
moisture...and thus gappy light showers. Best coverage of showers
will be in central New York with aid of lake moisture and stronger
dynamics. In fact...model soundings /NAM in particular/ show
marginal instability...and there have already actually been
a few lightning strikes upstream overnight in far western Ontario
/north of Lake Superior/. Thus I added slight chance of thunder to
accompany the showers mainly north of the New York thruway. In the twin
tiers...showers will be hit-or-miss scattered...sprinkles may be
the more appropriate term. Southern reaches of our area including
the Wyoming Valley PA may get no precipitation at all from this
system.

Overnight tonight...vorticity lobe rounds the transient upper low moving
through Quebec...and what can be considered the real cold front
will quickly blast through the area with strong cold air advection
resulting below zero celsius 850mb temperatures overtaking our
area 06z-12z Sunday. And with that...the introduction of lake
effect rain showers late tonight across the New York thruway
corridor...northwestern Catskills...and Mohawk Valley-Tug Hill
plateau.

&&

Short term /Sunday through Monday night/...
415 am update...
cool blustery day Sunday...with clouds and some lake effect rain
showers...then quiet Monday with moderating temperatures.

Cold front will have cleared well through the area by dawn Sunday.
850mb temperatures will be slightly subzero Sunday...meanwhile
Lake Ontario water temperatures are still 12-14 celsius. This cold
air aloft with Stout west-northwest flow off of lakes Huron and Ontario
Sunday...and model soundings suggesting lake-modified air mass
mixing to at least 10 kft above ground level...will be more than adequate to
yield Clouds Lake effect rain showers Sunday for much of central
New York and extending to some of the western Catskills...even a
bit into Sunday night before ending. Indeed...the 85omb ridge does
not even reach US until Monday morning. Farther south...moisture
will be trapped under developing subsidence inversion...so a good
amount of stratocumulus figured Sunday...then some diminishing of
it Sunday night. Strong pressure gradient and a lot of mixing
Sunday will yield 15-20 miles per hour winds with gusts 25-30 miles per hour.

Surface ridge will pass through Monday...with much lighter winds
and dry weather. Though remains of lake stratocumulus will fall
apart...high clouds ahead of next warm front will also already be
streaming in out of the west. We will see some sunshine...but how
wide that window of it will be is uncertain. Then very mild Monday
night as warm front and clouds pass overhead...there could even be
some spotty showers in the northern zones.

&&

Long term /Tuesday through Friday/...
125 PM update...
medium range models have come into good agreement with system moving in
Tuesday night into Wednesday morning. While GFS has come on board with ec
regarding timing of frontal passage late Tuesday ngt, latest CMC is slower and
does not bring frontal passage through until Wednesday morning. Either way, have gone with
wpc guidance for system with chance showers. Northwest flow will follow system
as it pushes into eastern Canada, setting the stage for lake effect
showers until hipres builds in on Thursday.

Temperatures will climb well above normal on Tuesday ahead of system with highs
possibly reaching into the 70s drg the afternoon. Cold front passage will
quickly drop temperatures back down toward normal values through the end of the
long term.

&&

Aviation /14z Saturday through Wednesday/...
12z Sat update... for the most part...VFR is anticipated through
about 00z sun. The exception is krme...where MVFR ceilings should linger
through late morning (14-15z).

By early this evening...a solid MVFR cloud deck should enter upstate
New York...impacting ksyr and krme. Farther S...VFR should remain the
rule...although spotty MVFR ceilings can't be ruled out at
kith/kelm/kbgm...especially towards daybreak. Spotty -shra are also
foreseen...but vsby's should remain at or above 6sm.

Surface winds at or below 5 knots through 14-16z...should pick up out of the west or
SW for much of the afternoon (gusts of 20-25 knots are likely). Winds
should veer into the northwest late in the day or this evening.

Outlook...

Sun...MVFR ceilings are possible in the morning...especially ksyr and krme.

Sun night through Tuesday...mainly VFR.

Wednesday...restrictions are possible in showers.

&&

Bgm watches/warnings/advisories...
PA...none.
New York...none.

&&

$$
Synopsis...mdp
near term...mdp/pvf
short term...mdp
long term...pvf
aviation...mlj

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