Area Forecast Discussion
Issued by NWS Binghamton, NY

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FXUS61 KBGM 241450
AFDBGM

Area Forecast Discussion
National Weather Service Binghamton NY
1050 AM EDT Mon Jul 24 2017

.SYNOPSIS...
A low pressure system will continue to bring showers and storms,
heavy at times, through the day today. The system will start to
move away with rain tapering to scattered showers for tonight
and Tuesday. High pressure will finally bring mainly dry weather
for Wednesday.

&&

.NEAR TERM /THROUGH TONIGHT/...
1045 am update...
Made only minor changes to the forecast to adjust to current
radar/satellite/observation trends. Still expecting a line/area
of strong to possibly severe convection to break out over the
central srn tier and portions of n-central PA this
afternoon...which will push to the e/se into the early evening
hours...with some storms producing heavy rainfall in addition to
gusty winds and hail. Due to the recent heavy rain and resulting
flash flooding that occurred along the NY/PA border between
Binghamton and Waverly, have decided to keep the Flash Flood
Watch going until 8 pm this evening for this highly sensitive
area.

3 am...Low pressure system continues to bring rain, moderate to
heavy at times, over the area resulting in areas flooding/flash
flooding. Current radar shows that the very heaviest of the
rain has eased however parts of northern PA through Bradford and
Susquehanna Counties as well as the southern tier of New York
through Broome and Tioga Counties have already received 2 to 4
plus inches of rain resulting in flash flooding. There have been
reports of numerous road closures as well as water rescues.
While there isn`t a lot of instability left to work with,
concern is that on the larger scale, this low pressure system
continues to better organize itself as main shortwave continues
to dig SE toward the area. This will help set up continuing
large scale ascent heading into this morning aided by dual upper
level jet dynamics also setting up. In fact, multiple models
suggest this will help set up another period of moderate to
heavy rain right over northern PA into the central southern tier
heading toward 12z so expect much of this area that has already
been affected by flash flooding to see at least another half
inch to inch of rain by mid morning. This will result in
continuing potential for flooding with localized areas of flash
flooding right through Monday morning across the twin tiers east
into the Catskills and south through the remainder of NE PA
where a Flash Flood Watch remains in effect until midday. Again,
biggest concern within these areas will be areas that have
already received flooding.

Later Monday morning, there will likely be a lull in
rain/showers as the initial slug of moisture finally moves off
to the east. However the main upper level trough will still be
upstream and this will finally swing through during the
afternoon interacting with surface trough which will still be
hung up over western NY. This coupled with instability due to
weak heating will help spark another round of showers and storms
which will likely develop over the lake plain and move east/SE
through the area. The good news is that deep layer moisture
won`t be quite as significant with PWATs only 1.25 to 1.5 inches
as opposed to 1.75+ inches. Also, the line looks to be fairly
progressive. Ordinarily this would mean flooding/flash flooding
would not be a big concern however given current flooding and
how little of a break there will be any heavier showers/storms
could result in renewed flooding for areas that have already
experienced flooding. The other concern is that models are
indicating the potential for upwards of around 1000 j/kg of ML
CAPE over the Finger Lakes with deep layer shear near 40 knots
so it`s possible some storms could even become severe and
produce strong winds. However this will be dependent on whether
any sunny breaks and resultant instability can develop. Best
chance for any severe storms will be across NE PA north into the
southern tier and N/W into the Finger Lakes.

Monday night...loss of daytime heating will result in
showers/storms diminishing in intensity however the upper trough
will be very slow to push across the area and this will result
in continuing lighter showers across the area. Temps will cool
down with lows in the mid to upper 50s.

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
Tuesday...Upper trough will be slowly moving away however
indications are that enough moisture will remain on the backside
of the system to still result in some continuing isolated to scattered
showers under considerable cloud cover. Temps will be cool for
this time of year with highs generally in the upper 60s to low
70s.

High pressure finally builds in Tuesday night bringing dry and
cool weather with lows in the mid to upper 50s.

Mainly dry weather can be expected for Wednesday with
temperatures moderating a few degrees as the high moves off to
the east setting up a return flow from the south. A couple
isolated showers or storms will be possible in the afternoon but
otherwise expect a mainly dry day.

Mainly dry weather continues Wednesday night though a few
isolated to scattered showers may be possible in central NY
ahead of an approaching frontal boundary.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
5 am update...In the big picture, weather looks to turn more
active again for Thursday into Friday as a frontal system moves
through. Forecast models disagree on the details of this system
though so it`s a little early to know whether there will be
significant impacts from it in terms of either severe weather or
hydro issues. Behind this system, at this point next weekend
looks to see an overall drying trend with seasonable
temperatures.

&&

.AVIATION /15Z MONDAY THROUGH FRIDAY/...
Rain continues into this morning with most site seeing VFR
predominate with occasional drops to MVFR cigs possible. The
exception will be KAVP where the rain is a bit heavier so expect
mainly MVFR with with visibility occasionally dropping to IFR
in heavier rain until around 14z. Most sites should see a lull
in the rain by later this morning however another round of
showers and storms will move through in the afternoon after 18z
bringing further restrictions to at least MVFR for most sites.
Confidence in convection is high enough to mention thunder in
the TAFs for all sites except KRME.

Showers and storms finally wind down this evening but expect a
low stratus deck to set up by the overnight. Most sites should
see fuel alternate MVFR with IFR cigs likely for KITH/KRME/KBGM.


Outlook...

Tuesday ...Periodic restrictions in showers as well as low cigs.

Wednesday...Mainly VFR.

Thursday & Friday...Chance of showers-storms with associated restrictions.

&&

.BGM WATCHES/WARNINGS/ADVISORIES...
PA...Flash Flood Watch until 8 PM EDT this evening for PAZ038-039.
NY...Flash Flood Watch until 8 PM EDT this evening for NYZ055-056.

&&

$$
SYNOPSIS...PCF
NEAR TERM...BJT/PCF
SHORT TERM...PCF
LONG TERM...PCF
AVIATION...KAH/PCF



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