651
FXUS61 KBGM 251357
AFDBGM

Area Forecast Discussion
National Weather Service Binghamton NY
957 AM EDT Sat May 25 2024

.SYNOPSIS...
A frontal boundary will bring scattered showers and thunderstorms
to the region this afternoon through this evening. This system
sweeps through quickly, as Sunday will be mostly dry before the
next system moves in late Sunday evening and into Monday.

&&

.NEAR TERM /THROUGH SUNDAY/...
950 AM Update...
The forecast was updated to finesse the details of anticipated
convection this afternoon; onset another hour or so quicker if
anything, and also narrowed the window to the most likely
timeframes. Temperature forecast was also adjusted for resultant
earlier cooling in the northwest as the storms start
developing.

Model soundings especially in the western half of the area show
steep low level lapse rates, with inverted-V appearance through
at least 5000-6000 feet above ground. One of those deals where
any thunderstorms or even shower cores should easily mix down
gusty winds this afternoon. Despite shear being somewhat
limited, this favorable boundary layer for mixing down of winds
supports the marginal risk for potential isolated severe
thunderstorms from the Storm Prediction Center, for counties
along and west of I-81 as well as Chenango-Madison-Oneida
counties. Confidence has increased for at least showers-embedded
thunder to make its way across the whole area late afternoon-
early evening, but the farther east it goes the less
instability it will have to harness and thus more limited
coverage of thunder and gusty winds.

Previous discussion...
High pressure is still in control this morning with dry
conditions across the area. Ridging flattens out later today and
low level southwesterly flow develops, which will start to
increase moisture this afternoon. Although dew point
temperatures this morning are generally in the mid to upper 40s,
this push of moisture will increase dew point temperatures into
the upper 50s to low 60s by late afternoon. Forecast soundings
show little CAPE at first with the very dry air in place,
however where the surface dew point temperatures increase and
theta-e advection is maximized (generally west of I81),
instability should be sufficient enough to support convection
with CAPE values increasing to 700 - 1200 J/kg out ahead of the
approaching shortwave this afternoon. How far eastward any
convection will survive will be dependent on the increase
moisture. Latest CAMs may be a little too bullish on how
eastward thunderstorms spread this afternoon, as forecast
sounding indicate too much dry air generally east of I81, which
may be tough to overcome. However, the HRRR shows a line of
storms pushing completely across our forecast area from this
afternoon through this evening. Definitely will have to do a
mesoanalysis later today to check on moisture advection, but for
now there is just too much uncertainty to say for sure that
storms will be able to hold together all the way from western NY
to the Hudson Valley.

SPC drew the eastern extent of the Marginal risk line for
severe thunderstorms almost directly over the I81 corridor. It
should be noted, that 0-6 km shear is only forecast to be 25 to
30 knots, but that may be enough to support some strong winds
approaching severe limits, especially if instability can exceed
1000 J/kg of CAPE.

All guidance agrees that this system will exit the region
overnight, leading to cool and quiet conditions late tonight/early
Sunday morning. With the added moisture from the showers and
storms as well as skies clearing out some, patchy fog/low
stratus may develop. Overnight lows will be in the mid 50s to
low 60s, but could be cooler where skies clear the most.

Sunday should remain mostly dry through the day, but another
shortwave arrives possibly as early as Sunday afternoon. This
will kick off another round of scattered showers and
thunderstorms in the vicinity of a stationary front that will
aligned west to east across northeast PA. At this time, the
Poconos Region to the Catskills will be most likely to see some
afternoon storms develop on Sunday.

&&

.SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/...
410 AM update...

A warm front associated with our next storm system is expected
to approach from the south Sunday night, bringing a chance of
showers late, especially for our southern and western areas. The
main area of low pressure will shift from the Midwest into the
Great Lakes Monday and as the low lifts northeastward, the warm
front will continue to press north across the CWA putting the
entire area into the warm sector. A strong low level jet out of
the south-southwest will aid in drawing up plenty of moisture-
rich air with PWAT values 1.50-1.75 inches for most. Putting all
this together, widespread showers and embedded thunderstorms
are expected which can produce locally heavy rainfall Memorial
Day.

Thunderstorm activity does look limited with CAPE values
struggling to get above 500 J/kg but bulk shear is 30-40 knots.
With the deep moisture in place, heavy rain with the potential
for ponding or even localized flash flooding seems to be the
bigger concern, especially in areas that see multiple rounds of
rain Monday into Monday evening. The WPC has our area under a
marginal risk for excessive rainfall with NE PA, the Twin Tiers
and the Southern Catskills in a slight risk. That area in
particular is where the models have been honing in on the
highest rainfall totals of generally 1-2 inches. There is still
some uncertainty with regards to when the heaviest rain falls,
but the best chance is during the afternoon and evening with the
heating of the day and along and ahead of the cold front
associated with this storm that will be pressing eastward in the
afternoon and evening. Drier, cooler air will filter in behind
the front and shower activity will taper off later Monday night.

Highs Monday are expected to be mostly in the 70s, with some of
the higher elevations, mainly in the Catskills, stuck in the
upper 60s. Lows Monday night will be in the 50s to near 60
degrees.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
410 AM update...

As the low pressure system departs to the northeast into
Canada, a broad upper trough will settle in over the region
Tuesday through Thursday with a few embedded shortwaves rotating
through. This will keep the area unsettled with a chance of
additional showers. Shower chances will be highest during the
afternoon hours during peak heating. Instability is expected to
be pretty limited so the risk for thunder is low during this
time. The upper trough starts to shift to the east late in the
week and a drier trend is expected.

With a cool, northwest flow in place much of this time, a
downward trend in temperatures is expected. Highs Tuesday are
expected to range from the upper 60s to mid 70s. Wednesday and
Thursday will be in the 60s, and parts of the area Thursday may
do no better than the low 60s. Widespread 40s are expected for
lows Wednesday and Thursday nights. Temperatures are expected to
slowly moderate late in the week as the trough moves off the
coast.

&&

.AVIATION /14Z SATURDAY THROUGH WEDNESDAY/...
Mostly VFR conditions expected through the period. There will be
a chance for late afternoon and evening showers/thunderstorms
across the region with the highest confidence in TS at ITH,
ELM, and BGM. After any showers or storms push through,
expecting VFR conditions until early Sunday morning when MVFR to
IFR fog and ceilings will be possible.

Outlook...

Sunday...Morning fog, otherwise mainly VFR expected.

Monday through Wednesday... Restrictions possible with
scattered showers and thunderstorms, especially on Monday and
into Tuesday.

&&

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

&&

$$

SYNOPSIS...MPK
NEAR TERM...MPK/MDP
SHORT TERM...DK
LONG TERM...DK
AVIATION...MPK