Area Forecast Discussion
Issued by NWS Binghamton, NY

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FXUS61 KBGM 311055

Area Forecast Discussion
National Weather Service Binghamton NY
655 AM EDT WED AUG 31 2016

A cold front will slide through the region late this afternoon
and tonight with scattered showers and thunderstorms. Behind this
front, cooler and dry weather will last into the weekend as a
large Canadian high pressure system dominates our region.


340 am EDT update...HRRR and HRRR-X were onto something and indeed
a lot more radar echoes developed rapidly over western NY than I
thought! Most of this precipitation was not reaching the ground
but some was. So will use HRRR and add some sprinkles to forecast
for much of central NY for the early morning hours. The HRRR
brings this light patchy precipitation across all of our central
NY counties and north central PA through 14z or so. Believe with
insolation late this morning the precipitation will break up by
15z-16z the latest. So will have sprinkles through about 14z or so
and use HRRR for timing. Rest of forecast will remain unchanged
for now.

Previous discussion...IR imagery shows plenty of high clouds
moving east during the early morning hours which was associated
with a southwesterly moisture feed aloft well in advance of an
upper level trough which was starting to drop southeastward from
northern Ontario. This upper level trough was pushing a cold front
southeastard which has reached across the central Great Lakes
region. Radar imagery shows isolated to scattered showers and a
few thunderstorms moving toward the eastern Great Lakes region.

The upper level trough which was supporting the front will move
southeast today but its main influence will remain north of our
region initially and hence the frontal boundary reaches only to
Lakes Erie and Ontario by 00z Thursday. In advance of the front,
since the pressure gradient was not that impressive, there was a
lighter west to southwest flow of air in the low-levels which
will advect a ribbon of higher theta-e air west of the Appalchians
to western NY and the Lake Ontario plain in north central NY by
afternoon. Meanwhile, there will be another ribbon of higher low-
level theta-e air advecting northeast across southern PA to
northeast PA and southeast NY this afternoon east of the
Appalchians. Since the forcing was fairly weak initially, we don`t
see much precipitation before 18z in any of our CWA so we have
kept a dry forecast. Models were mostly dry before 18z, except for
the HRRR and HRRR-X which have a slug of precip moving through
overnight. Both of these models are way overdone at this early
hour with the on-going isolated to scattered convection and will
not use.

During the afternoon with insolation we expect isolated to
scattered convection to develop as upper level height falls begin
as another short wave southwest of the main wave in Quebec moves
into the Great lakes. This feature will be the main impetus to
increase the low-level southwesterly flow ahead of the surface
front and also push the front across central NY and northeast PA

Model CAPEs are unimpressive t6his afternoon being less than 1000
J/kg and bulk shear magnitudes 0-6 km running at or below 25
knots. So we are not expecting severe thunderstorms and concur
with SPC`s general thunder outlook for today. We believe the bulk
of the convection will be from late afternoon well into the
evening with the movement of the front and upper level wave. The
highest chances for precipitation will be initially in north
central NY and northeast PA this afternoon where there is a deeper
ribbon of low-level moisture. As the front presses into central NY
this evening, low-level moisture pooling in northeast PA in
advance of the front will lead to higher POPs for showers and
storms and have this in grids in these areas.

After fropa overnight tonight in central NY, lingering showers
will continue as low-level moisture, lifting ahead of front and
short wave and some upsloping on northerly winds keeps chances for
precip going. Farther south into northeast PA, fropa occurs late
tonight so have some showers continuing down there as well.


Much cooler Canadian high pressure will slide across NY State on
Thursday. With the upper level trough axis moving across the
region on Thursday, we can`t rule out an isolated rain shower
during the day. For most areas, mostly cloudy skies early in the
day will slowly give way to clear skies after sunset.

Dry, clear weather will hold through the weekend. Temperatures
will warm from the lower 70s on Friday to the middle or upper 70s
on Saturday.


320 PM Update...
High pressure extending from the surface well into the upper
atmosphere will remain entrenched across much of the Great Lakes
and Northeast through Tuesday. Little to no chance of rain is
currently expected all these days. Medium range global models are
struggling with what is currently TD Nine. GFS/Canadian models
would bring the strengthening system across northern Florida and
closest to the Atlantic coast this weekend and early next week.
These models are currently outliers from the current suite of
specific hurricane model tracks and other global ensembles which
carry the system well out to does the 12Z ECMWF (at least
through Sunday). For now...the official NHC cone will be followed
which keeps this system well to our south extending dry weather
across CNY/NEPA. Lack of substantive rainfall does not bode well
for drought conditions.

Temperatures start off seasonably cool this weekend and moderate
by this time next week.


Scattered light showers will move across most of central NY and
northeast PA this morning and early afternoon. The showers will
come from a VFR mid-deck. As the showers pass south, scattered
thunderstorms will form on the north edge of this precipitation in
north central NY this afternoon and then spread south. Thunder
probabilities are still low enough this far out and instability is
marginal in NY so left thunder out of NY terminals for afternoon
Put thunder in KAVP where more instability exists into this
evening. Rest of terminals have tempo groups for MVFR-VFR in
showers from 20-24z in RME and SYR, 22Z-02Z ITH, and ELM, 23z-03z
BGM and tempo for TSRA AVP 00z-04z.

A cold front will cross the region later tonight and bring mainly
MVFR CIGs to most terminals after 06Z.

Winds will be southwest 5 to 10 knots today and this evening and
then northwest under 10 knots tonight.

Thursday- Sunday...VFR.




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