Area Forecast Discussion
Issued by NWS Binghamton, NY

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FXUS61 KBGM 271427
AFDBGM

Area Forecast Discussion
National Weather Service Binghamton NY
1027 AM EDT Thu Jul 27 2017

.SYNOPSIS...
A weak frontal boundary, will slowly cross the region today and
tonight, with a good chance for showers and thunderstorms in
central New York. A few showers and thunderstorms will linger
tonight and Friday. Friday night, a low pressure system along
the east coast, will bring some mostly light rain to northeast
Pennsylvania and the southern Catskills. This weekend into early
next week looks dry, as high pressure builds down from eastern
Canada.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
1015 am update... An area of showers continues to traverse much
of CNY late this morning. Present indications are that the
steadier showers exit from W-E across CNY and PA`s northern tier through
early afternoon. Brief heavy rainfall is possible and this will
be monitored.

From about 1-2 pm onward, it looks like convective activity will
become more scattered in nature, but will also feature thunder
more prominently, as the atmosphere destabilizes. The latest
visible satellite imagery shows thinning cloud cover over the
western southern tier of NY and northwest PA. We expect this
decrease in clouds to come eastward and result in breaks of sun
for NY`s southern tier and NEPA this afternoon, hence the
increased instability. Model projections would indicate the
potential for ML CAPE of 500-1000 j/kg this afternoon over
roughly the southern half of the forecast area, along with some
deep-layered shear (0-6 km values of 30-35 kt). Thus, localized
strong-severe storms are not out of the question, with gusty
winds and heavy downpours the main threats. This is well in line
with our current Hazardous Weather Outlook and information
posted to social media.

Once breaks of sun develop, we should still see highs into the
70s this afternoon.

Previous discussion... 330 am update...

Still a flash flood and damaging wind threat today but less
ominous then what was forecasted yesterday.

Some light showers and sprinkles moving into the finger Lakes
now. Mostly a mid deck so little accumulation. These showers
extending west to Michigan are ahead of a cold front moving
south. Best coverage to stay in upstate NY.

This afternoon with some heating, thunderstorms are possible.
Cape rises to around 1000 with bulk shear around 35 kts. Low
level winds are light. A weak short wave aloft and a weak
surface front moves southeast through the area. Pwats between
1.5 and 2 inches now into the afternoon. Some isolated heavy
rain is possible. With weak forcing in the area of steadier
rain, thunderstorms will be isolated there. Further south better
instability but still weak forcing. Any flash flooding will be
isolated at most. Rainfall amounts half an inch to an inch will
be common in NY with little in PA. SPC has the area in a
marginal risk of severe due to winds almost entire area.
Potential is there for a few but again will not be widespread.
In PA this threat for the afternoon into the early evening.
Cloudy to mostly cloudy skies will keep it on the cool side
with late day highs in the mid and upper 70s.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY NIGHT/...
330 am update...

Showers and thunderstorms will continue into the evening then
taper off and move out of the area toward midnight. A small
threat of flash flooding and damaging winds in the evening from
the southern tier of NY to NE PA. Some clearing allowing
temperatures to fall into the upper 50s and lower 60s.

Threat for heavy rain Friday and Friday night reduced. For the
overnight into Friday morning very little happening. the cold
front will be in Virginia. Models are slower still on the
progression of a surface low and upper level short wave
upstream. Friday morning the low in the Ohio Valley while the
short wave is in Michigan. Friday night the low moves across
Virginia while the short wave drops into the Ohio Valley. The
surface low strengthens while the upper level trough closes off
further slowing the progress. Steady rain may hold off until
Friday night. The northward progress may just be into NE PA and
Sullivan County NY. Most models keep the heaviest rain to the
south of our CWA. An average rainfall amount in the far south
would be under an inch. Thunderstorms may not be an issue.

highs mid 70s north to around 80 south Friday. Lows mid 50s NY
to around 60 PA.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
Saturday...Models continue to show significant differences with
position and timing of mid Atlantic system. The GFS/ECMWF is
farther north and slower than the NAM so will carry chance/slight
chance pops for northeast Pennsylvania and the southern
Catskills. Highs will range in the lower to middle 70s.

For the remainder of the period, upper level low will shift off
the east coast and lift northeast into coastal New England
while a flat ridge briefly builds over the northeast. Late in
the period the next upper level trough drops through the Great
Lakes region. Saturday night through Monday will be dry with
surface high pressure in the vicinity. Tuesday and Wednesday
isolated thunderstorms will be possible during max heating. On
Thursday the chance for showers/thunderstorms increases as the
next cold front approaches the region.

Temperatures through the period will be within a few degrees of
seasonal normals.

&&

.AVIATION /14Z THURSDAY THROUGH MONDAY/...
7 am update...

Mainly VFR conditions continue. Ceilings at AVP have fallen to
MVFR fuel alternate. This will continue until around 16z then
become VFR into tonight. The NY sites will fall to MVFR this
morning from the cold front dropping southeast. RME may be IFR
(cig/vsby) with the front around 16z. This afternoon ceilings
in central NY lift back to VFR.

Isolated thunderstorms and showers will develop during the
afternoon hours over NY`s southern tier (KELM, KITH, and KBGM).
This may reduce conditions to MVFR at times. Not long enough to
include.

Late tonight some MVFR and maybe IFR conditions in fog and low
clouds at ELM/BGM/AVP.

Surface winds south to southwest now and light. During the day a
shift to west at 4 to 8 kts, then light and variable tonight.

Outlook...

Friday and Friday night...Restrictions in ceilings/rain are
most likely to occur at KAVP, with some potential at KBGM. Other
sites will probably feature VFR conditions.

Saturday-Monday...VFR.

&&

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

&&

$$
SYNOPSIS...TAC
NEAR TERM...MLJ/TAC
SHORT TERM...TAC
LONG TERM...RRM
AVIATION...TAC


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