Area Forecast Discussion
Issued by NWS Binghamton, NY

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000
FXUS61 KBGM 281659
AFDBGM

Area Forecast Discussion
National Weather Service Binghamton NY
1259 PM EDT Wed Jun 28 2017

.SYNOPSIS...
High pressure will yield fair weather today through early
Thursday, though an isolated shower or thunderstorm cannot be
ruled out around the New York Thruway and points north today as
a weak disturbance passes. Later Thursday through Friday, low
pressure moving through the Great Lakes will bring new rounds
of showers and thunderstorms.

&&

.NEAR TERM /THROUGH TONIGHT/...
1000 am update...
No significant changes made to the forecast this morning. Mostly
clear skies out there currently...should be replaced by a deck
of strato-cumulus by the afternoon and a slight chance of a few
showers and storms.

230 AM Update... Fairly quiet weather in the very near term,
but thunderstorm potential will increase by late Thursday.

Though high pressure centered over the Midatlantic states will
be our main weather influence, even today in our busy weather
pattern is not without a nuanced small chance of rain at least
for a part of our area. Water vapor imagery depicts a shortwave
extending from sharper upper trough/small compact upper low
around James Bay, down to Georgian Bay of Lake Huron. This wave
generated convection Tuesday afternoon-evening. Models suggest
the wave will weaken yet advect into northern New York late
morning to early afternoon. This along with left exit region of
an upper jet may be enough to generate isolated instability
showers- thunderstorms roughly along and north of the New York
Thruway. That being said, vast majority of the area will have a
welcome dry break today through early Thursday, especially
Northeast PA to Finger Lakes-Southern Tier-Catskills NY. Even to
the north, mostly dry.

A chilly start today, in the upper 40s-lower 50s with patchy
valley fog; however temperatures will moderate compared to
Tuesday with highs of mid to upper 70s except lower 70s for
elevated terrain. Lows tonight will be in the 50s, with
increasing high clouds towards dawn ahead of the next system.

On Thursday, warm air advection will finally realize daytime
highs right around climatology in the upper 70s-lower 80s.
Southwesterly low level jet will also be pumping in increasing
moisture, with dewpoints climbing into lower to mid 60s in late
afternoon. Warm front will be lifting into the region yet with
weak if any support aloft. Atmosphere will be initially capped
with low amplitude ridging aloft, yet shortwaves will be
crashing into the ridge and flattening it with time late
Thursday. The increasing moisture will add to the rising
temperatures to yield instability. Thunderstorms, some of which
could reach severe limits with gusty wind potential, will
develop upstream and start trying to get into at least Central
New York late in the day.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
245 AM EDT Update...The main concern for this period will be
around the severe weather potential for Thursday evening...
possibly lasting even into the overnight. The set up will be the
passage of a warm front at the surface coupled with a shortwave
aloft and daytime heating. This will spark storms over western
NY which are likely to move into the region from west to east
beginning by mid evening. There remains some uncertainty
regarding how unstable it will be but generally speaking models
indicate ML CAPE values maxing out in the 800-1200 j/kg range.
Shear will be quite good as well with models indicating
0-1/0-3/0-6 km bulk shear values of 25/40/40 knots respectively.
Also worth noting, models continue to indicate low level
helicity values of 150+. However potential limiting factors for
severe weather will be the lack of strong height falls and
questionable jet support. Also, if storms don`t move in until a
little later in the evening there may be less instability to
work with so they could weaken. Thus, still not a high
confidence scenario but will continue to mention severe threat
in the HWO with the best chances generally being over central NY
zones. Damaging winds and large hail will be the biggest
threats. Also some uncertainty on how long storms last into the
overnight with NAM indicating another wave triggering
showers/storms past 6z. If this solution were to verify, there
may also be hydro concerns if storms repeatedly occur over the
same areas. PWATs are indicated to be 1.5+ inches so any storms
will be capable of producing heavy rainfall. In addition to
stormy, Thursday night will be quite warm and muggy with lows
only dipping to the mid to upper 60s.

The warm, muggy, and storm pattern continues into Friday. There
will likely be a break by Friday morning however by afternoon
another wave moving through aloft will be well timed with
daytime heating to trigger more showers and storms. These look
to be most numerous over central NY closer to the warm front.
Shear does not look to be as strong Friday so not expecting any
significant severe weather. Temps will be quite warm and humid
due to SW flow with highs in the 80s and dew points in the upper
60s. This will be followed by another warm and muggy night
Friday night with storms potentially lasting into the evening
before diminishing overnight.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
320 PM EDT Update...
Very minor changes were made to the forecast period. Updated
forecast with new WPC guidance.

SW flow aloft will prevail through most of the forecast period.
Multiple shortwaves are forecast to move across the region
through the period. This type of pattern will lead to an
unsettled weather, thus there is a chance for precip Friday
night through Sunday. Monday still appears to be our dry day as
high pressure briefly builds over the region. Showers may
re-develop over the region again on Tuesday.

It needs to be emphasized that although at least a chance of
showers/storms will be in the forecast through this period, any
all-day washouts look highly unlikely, with significant rain-
free periods, and convective chances greater coincident with
peak heating during the afternoon/early evening hours.

&&

.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
Scattered VFR cumulus still expected through the rest of this
afternoon with a slight chance of a brief shower or weak storm
at KRME, KSYR and/or KITH. However, confidence still not high
enough to include in TAF. Winds will become westerly at 8-12
knots during the day with a few gusts 15 to 20 kt, before
diminishing and backing south or southeast this evening. VFR
conditions will continue tonight, though with increasing high
thin clouds, no valley fog is expected.

Outlook...

Thursday through Saturday...At least periodic restrictions
anticipated in showers/thunderstorms late Thursday onward.

Saturday night/Sunday...Generally VFR but scattered convection
could lead to brief restrictions.

Monday...VFR.

&&

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

&&

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



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