Area Forecast Discussion
Issued by NWS Binghamton, NY

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758
FXUS61 KBGM 191925
AFDBGM

Area Forecast Discussion
National Weather Service Binghamton NY
325 PM EDT Sat Oct 19 2019

.SYNOPSIS...
High pressure over our area will slide east tonight. On Sunday,
clouds and isolated showers will skirt northeast Pennsylvania
and the Catskills. Dry weather returns for Sunday night and
Monday with weak high pressure.

&&

.NEAR TERM /THROUGH SUNDAY NIGHT/...
3 PM update...

High pressure over the area now will exit to the east the rest
of today. With the dry low level air, frost and valley fog are
possible again late tonight. With more clouds and stronger
boundary layer winds fog will be less than this morning.
Low temperatures will also be warmer from the mid 30s to around
40.

High clouds are already moving into the far south from the
southwest. This is well ahead of the tropical remnants of
Nestor over the Florida panhandle. Light rain is now moving into
Virginia on its way northeast. More models now have some light
rain moving into northeast PA and the Catskills during the day
Sunday. Rain amounts may get to a tenth of an inch in the
Poconos. Clouds are expected across the entire CWA but most of
the clouds from the central southern tier to the western Mohawk
Valley will be mid and high clouds. High temperatures will be
warmest there in the upper 60s and lower 50s. For northeast PA
and the Catskills highs will be in the mid and upper 50s.

Late Sunday rain and clouds will start exiting to the east.
Skies become partly cloudy. Weak high pressure moves in late.
Valley fog will be possible again. Winds go light to calm.
Temperatures fall to around 40 for most of the area.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
Monday... Our region will be situated between Post-Tropical
Cyclone Nestor (moving farther off the southern Mid- Atlantic
coast) and low pressure over the Upper Midwest. The ridge axis
associated with surface high pressure will shift to our east
through the day as height/pressure falls spread eastward ahead
of the Midwest low. The day should be dry but high clouds could
start to overspread the area late. A warm southerly flow ahead
of the upstream trough will yield a mild autumn day with highs
in the mid to upper 60s (5-10 F above normal).

Monday night... Deep southerly flow in the pre-frontal warm
sector ahead of the Great Lakes cutter will continue to become
established over the area. The leading edge of rain showers is
forecast to approach from the west late. PoPs increase from
west to east overnight though there are still some timing
differences among the latest guidance wrt the onset of precip.

Tuesday and Tuesday night... The latest guidance has the low
lifting to the north-northeast across western Ontario and toward
Hudson Bay. The setup could provide a period of moderate to
perhaps locally heavy rainfall ahead of the front as a 50-kt
southerly low-level jet and plume of anomalously high PWAT air
(over +2 SD) arrives.

Differences among the models in timing/speed of the cold front
are notable, leading to some uncertainty regarding when the
heaviest rain falls and exactly how much falls. A more
progressive solution (e.g., 12Z GFS) would favor the heaviest
rain occurring from the late morning thru mid afternoon but with
lighter storm total amounts (QPF 0.5-1"). Conversely, a slower,
more amplified solution would delay the heavier/steadier rains
until late in the afternoon or Tuesday night. The heavy rain
threat would be greater in the latter scenario with some of the
slower, wetter guidance advertising localized QPF amounts
exceeding 1.5" (as indicated by the 90th percentile values from
the latest NBM v3.2). Given the low will likely become cutoff
and how amplified the downstream flow becomes, a slower solution
seems a bit more plausible.

Although we should be able to handle the runoff without much
issue based off QPF amounts from the current deterministic
forecast, the wetter envelope of models support low
probabilities for localized/minor flooding in poor drainage
areas. Accordingly, we will continue to monitor the flooding
threat over the coming days.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
A deep upper trough moves into the area Tuesday through Tuesday
night. A strong surface low tracks northeast from the midwest
through the western Great Lakes into northern Ontario. An
occluded front will move through our area with showers/ periods
of rain Tuesday and Tuesday night. Models have slowed a few more
hours but not as much as previous days. Ahead of this front and
lifting upper level trough will be a deep southwest flow of
moisture from the Gulf of Mexico. Precipitable water is expected
to be over one inch and be 2 to 3 standard deviations above
normal. With the jet support this could be another 0.50 to 1.5
inch rain event. With the rain this week, the flood potential
will need to be watched. With that said, the latest guidance
seems to be coming in just a touch lower with rainfall amounts,
as there really is no southern wave along the front this time
around. Highs near average and around 60 Tuesday.

A broad but not deep upper level trough will be over the area
Wednesday. A westerly flow of cool air will create lake
enhanced rain showers across our northern counties east of
Lakes Erie and Ontario. Cooler with highs in the 50s and lows
mid 30s to mid 40s.

Significant model differences are then evident by the end of the
week and into the early weekend. Used a blend of the latest
guidance which favors generally dry weather Thursday/Thursday
night with a chance of rain possibly arriving later Friday and
into the weekend. Forecast confidence is lower than average
Friday and Saturday as guidance is out of phase with potential
systems moving through. Temperatures are looking seasonable,
with highs in the mid-50s to low 60s and overnight lows in the
mid-30s to low 40s.

&&

.AVIATION /19Z SATURDAY THROUGH THURSDAY/...
120 pm update...

Valley fog has burned off and that will be the problem late
tonight but only for ELM. With boundary layer winds of 20 to 30
mph late tonight there will be less coverage and depth to the
river valley fog. For ELM have MVFR vsby fog from 08z to 13z
with a tempo for VLIFR from 09 to 13z.

The rest of the sites will be VFR through 18z Sunday. AVP will
have a 6k ft cig and maybe a few sprinkles by 18z Sunday.

Winds light and variable this afternoon. East to southeast winds
at 4 kts tonight. south winds around 5 kts Sunday.

Outlook...

Sunday afternoon through Monday...mainly VFR. Monday morning
valley fog possible at ELM again.

Monday night through Wednesday...restrictions possible in
showers.

Thursday...mainly VFR.

&&

.BGM WATCHES/WARNINGS/ADVISORIES...
PA...None.
NY...None.

&&

$$
SYNOPSIS...TAC
NEAR TERM...TAC
SHORT TERM...JRK
LONG TERM...JRK/MJM
AVIATION...TAC



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