Area Forecast Discussion
Issued by NWS Binghamton, NY

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FXUS61 KBGM 281105

Area Forecast Discussion
National Weather Service Binghamton NY
705 AM EDT Wed Jul 28 2021

Weak high pressure will bring clearing skies Wednesday, before
another storm system spreads showers and thunderstorms into NY
and PA Thursday.


Wet antecedent conditions and light winds will cause fog through
the early morning hours. Patchy dense fog will reduce visibility
to 1/2 mile or less at times.

Much drier air will move into NY and PA this morning, as
depicted on the model soundings. Fog and low clouds will
dissipate during the morning hours, with plenty of sunshine
forecast for the rest of the day. Temperatures will peak in the
middle or upper 70s, then fall into the 50s Wednesday night.

A frontal system will pull higher dew points and showers and
thunderstorms into NY and PA on Thursday. CAPE values (400 to
700 j/kg) will be lower than in recent events due to a brisk
northwest flow, evident in the 40-45 knot bulk shear vectors. It
appears the best instability remains southwest of our forecast
area until late Thursday evening.

However, the high degree of shear present in the atmosphere,
particularly within the 0-1km layer, indicates storms will have
the potential to generate rotating updrafts. A slight risk for
severe thunderstorms exists over our far southern forecast area,
with a marginal risk covering most of Central NY.


Our region will be between a frontal boundary to our south an
another approaching cold front from Canada Thursday night. The
instability and moisture present with the southern boundary has
trended a bit further northward with recent model runs across
northeast PA. We are also coming into range of several mesoscale
models as well with this event which are indicating a higher
shear environment will be present Thursday evening.

Several rounds of showers and isolated thunderstorms should
continue to move across central NY into the evening hours. Even
with the southern frontal boundary trending a bit northward,
instability it is still not anticipated to advect much further
northwest of the Catskills and NE PA.

Further south in NE PA instability is modeled generally from
300-800 J/KG which may just enough for a threat of strong to
severe thunderstorms given 40-50 knots of 0-6 KM bulk shear.
However, the column of dry air looks elevated coupled with a
tall skinny CAPE more indicative of a heavy rainfall threat
compared to severe weather. Still, a modest LLJ and decent storm
motions should be enough for these storms to have some gusty
winds. 0-1 KM bulk shear looks to be around 20 knots coupled
with helicity values off 200-300 M/S-1 which would promote some
rotational components to any thunderstorms where the
instability can advect sufficiently into.

Quite a range is still present within model guidance and
ensembles on how Thursday will evolve. It appears more likely
than 24 hours ago that most of NE PA into the Western Catskills
may realize a a risk for strong to severe storms. However,
Thunderstorms tend to run toward the highest amount of
instability which is still south of the area so would not be
surprised to see this trend south again.

If instability is realized, gusty winds and possible localized
flooding may occur if storms move over the same areas despite
somewhat fast storm motions. Low temperatures look warmer from
clouds and rain only around 60.

High pressure is slow to build in Friday. This is due to
northwest flow and moisture moving in with northwest flow off of
Lake Ontario. This is still expected to keep more clouds around
that blended model guidance with some lingering light showers
too. Temperatures only slowly rebounding into the 60`s and 70`s.

High pressure continues to build into the region with clear
skies and light winds. This sets up nicely for radiational
cooling with some locations still likely to fall into the 40`s.
Trended cooler than blended model guidance given the setup.


With full sunshine, temperatures should get into the 70`s
making for a great weather start to the weekend. A bit warmer
Saturday night compared to Friday night due to southwesterly
flow ahead of the next frontal boundary.

Another cold frontal boundary looks to pass through on Sunday.
Deep moisture and instability are modeled to be somewhat limited once
again with the front only providing enough lift for scattered
showers and perhaps a thunderstorm. QPF has trended higher
likely due to slightly higher amounts of instability modeled
Sunday afternoon. This front moves southeast of the region by
Monday and Tuesday though as usual some timing uncertainty is
present within the ensembles not totally eliminating the chance
for a shower or two. Highs in the 70`s with lows in the 50`s.


Saturated terrain and light winds will spur fog and low clouds
this morning. IFR restrictions are expected to develop at most
of our terminals, especially between 8z and 12z.

Fog and clouds will burn off between 12z and 14z, as much drier
air moves into NY and PA. VFR conditions will persist today. Winds
will be light.

Mostly clear skies and light winds are forecast Wednesday night.


Thursday through Friday...Scattered showers/thunderstorms and
associated restrictions possible, especially during the

Friday Night through Saturday...Mainly VFR.

Saturday Night through Sunday...Stray showers and thunderstorms
possible, otherwise mainly VFR.




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