Area Forecast Discussion
Issued by NWS Binghamton, NY
FXUS61 KBGM 300804
Area Forecast Discussion
National Weather Service Binghamton NY
404 AM EDT SAT JUL 30 2016
Scattered showers and storms this afternoon will become more
widespread this evening and tonight across northeast Pennsylvania
and a good portion of central New York. Heavy rain is possible.
Scattered showers and storms continue into Sunday before moving out
Sunday night. A few showers linger into Monday with conditions
drying out into the middle of next week.
.NEAR TERM /THROUGH TONIGHT/...
400 am update...
Main concerns in the near term are focused around the increased
potential for heavy rain basically from this afternoon through
tonight. Definitely a challenging forecast today and tonight with
various elements to try to get a handle on.
This morning...Conditions are relatively quiet with weak ridging
aloft combined with an exiting sfc high to the east. A few rain
showers have developed along the NY/PA border in Steuben county and
also into e-central PA near and south of Hazleton. Sufficient deep
moisture through the column combined with divergence aloft and a
weak amt of instability are the main contributors to these showers.
Will likely see these showers move slowly eastward...initially
maintaining their intensity...but likely increasing in coverage and
intensity into the late morning and early afternoon.
This afternoon...An approaching upper trough and associated vort max
will become negatively tilted across the Great Lakes as the upper
ridge over nrn New England amplifies into ern Ontario/wrn Quebec.
The combination of this broad large-scale lifting...afternoon
heating producing ML CAPE values 500-900 J/kg and an approaching
surface inverted trough from the SW...convection is expected to
increase from the southern Tier of NY into NE PA. Severe weather is
not expected. However...thermal/moisture profiles within this
unstable environment will be favorable for heavy rain. Steering
winds will be between 15 and 20 kts...which will allow storms to move
rather slow and increase the potential for localized flooding
concerns. Areas of NE PA may see around a half to 1 inch of rain
this afternoon and possibly more in isolated locations.
Temperatures today will warm only into the upper 70s and lower 80s
as cloud cover inhibits the amt of heating.
Tonight...There is expected to be a notable increase in low level
moisture this evening as the inverted trough acts in phase with an
area of high pressure off the coast of New England to strengthen the
pressure gradient. A channeled area of warm moist air will get
transported nwd through the mid-Atlantic states and get efficiently
deposited across our forecast area in the form of widespread rain
showers. There will likely be embedded thunderstorms within the
rain...but the main concern is the potential for additional heavy
rainfall. The convective mode will change slightly as well from a
more cellular form this afternoon into more of a broad layer lifting
convective mode on the nose of this moist unstable air mass.
When the daytime heating subsides this evening the afternoon
convection will likely decrease in intensity...but quickly
transition to a large plum of rain showers with embedded storms over
NE PA into s-central NY. There is still some uncertainty regarding
the movement and development of this area of mod to hvy rain.
Differences are noted on both the large scale models and small scale
convective models with some members/models taking the afternoon
convection off to the e/ne quickly with a break before the re-
development occurs in the evening...but mainly confined along and/or
east of I-81. Other guidance hangs the afternoon convection back
across wrn/cntrl NY and blossoms the evening convection over much
of central NY and NE PA through the overnight hours. At this point
am leaning toward the second solution as the steering winds remain
weak...which may allow the convection to not be as progressive as
the first solutions suggests.
Either way it appears there may be portions of the Twin Tiers and NE
PA that see significant precipitation today and tonight...with
localized flooding a possibility...especially in poorly drained
urban areas. Will hold off on a flash flood watch at this point and
allow next shift to issue a short-fused watch if need be.
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
A diffuse area of low pressure will lay across the eastern FA on
Sunday, buoyed by a developing low level jet. Key to the strength
of the precipition on Sunday will be the jet development. NAM12 is
strongest and most-defined with the jet, pulling a 30+ knot 850mb
bullseye from PA into NY just east of I-81. The Euro is much
weaker and more diffuse with the jet, drifting it eastward along
the NY/MA/CT borders.
The upper level trough swings across us on Monday, keeping a
chance for showers and thunderstorms in the forecast.
.LONG TERM /TUESDAY THROUGH FRIDAY/...
Medium range models show fair agreement through the extended
period which leads to higher confidence than average. Monday
night, due to a departing upper level wave and associated surface
low pressure will keep chc/slight chc pops primarily over eastern
parts of the forecast area. Tuesday through Thursday night looks
dry across the area as upper level heights rise with a large
surface high pressure system across the northeast. The airmass
will become increasingly more hot and humid as the week goes on.
On Friday, an approaching surface cold front will bring the
chance for showers and thunderstorms especially Friday night.
.AVIATION /08Z SATURDAY THROUGH WEDNESDAY/...
VFR conditions with light and variable winds through at least this
morning before a round of convective showers and possibly a few
storms develop in the afternoon. Have added tempo groups to ELM
and BGM this afternoon for -SHRA...and a prevailing FM group to
AVP with higher confidence to the south in rain showers and also
the potential for TS. Deep layer moisture will increase later in
the day and this evening with OVC VFR conditions becoming MVFR and
eventually lower IFR conditions at AVP closer to 06Z as a strong
push of moisture arrives from the south. May see +RA at AVP later
Sat night - Monday...Restrictions possible with showers and
Monday night - Wednesday...VFR.