Area Forecast Discussion
Issued by NWS Binghamton, NY
FXUS61 KBGM 291958
Area Forecast Discussion
National Weather Service Binghamton NY
358 PM EDT FRI JUL 29 2016
After a fair and mild night tonight, a series of small low
pressure systems will lead to increasing chances for showers and
thunderstorms this weekend and early next week.
.NEAR TERM /THROUGH SATURDAY/...
Visible satellite imagery shows scattered to broken cumulus across
much of northeast PA and central NY with clumping of the cumulus
fields and more vertical growth apparent in the higher terrain
areas of central NY, especially east of I-81. Since forcing and
shear is fairly weak this afternoon as water vapor and NAM80 300
mb PV fields show only a weak short wave working into
Pennsylvania this afternoon. SPC mesoanalysis does show some cold
advection at 500 mb with this small upper wave feature. Low-level
moisture was not that impressive with surface dewpoints in the
lower to mid 60s. Hence mixed layer CAPEs were generally between
250 J/Kg and 500 J/kg. Additional heating will elevate CAPEs to
around 500 J/kg to 750 J/kg at best. Wind shear was weak and with
weak forcing aloft, upsloping into the terrain will be the driving
factor this afternoon and early afternoon with the diurnal heating
for showers and some thunderstorms. So have adjusted POPs with our
terrain tool with higher chances in the higher terrain and lower
chances for precipitation in valleys, with no more that isolated
or slight chance POPs for afternoon/early evening.
For tonight, with nocturnal cooling we see precipitation falling
apart and diminishing. Mid to high clouds will stream into much of
northeast PA and southern NY. This, in addition to a fairly dry
surface layer should preclude significant valley fog formation.
Saturday will see a short wave and associated convective activity
arrive in the morning mainly for northeast PA and then another
wave later in the day which will coincide with maximum heating.
This second wave Saturday will increase chances for showers and
thunderstorms from south to north in our forecast area with likely
POPS late in the day in the Poconos to chance and slight chance
farther north in central NY. CAPEs are projected to remain below
750 J/kg especially GFS and even the NAM is not showing that
impressive CAPEs. But the forcing from the waves will lead to more
low-level moisture advection on southeast winds and hence better
chance for showers and some storms Saturday versus Today.
.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
Went with a model blend of the CMC and Euro for this period as
GFS and NAM both look like they are overdeveloping the
southeasterly low- level jet for Sunday in advance of the main
upper level wave. With more low-level moisture transport both NAM
and GFS looks overly wet for Sunday. The Euro and CMC show a low-
level southerly jet that works northeast Saturday Night and moves
east of the region on Sunday. The NAM and GFS linger this feature
through Sunday. So POPs will be high chance to likely for showers
and some storms for Saturday night as per all 4 models mentioned
above. For Sunday into Sunday night, trended down on POPs
following the EURO and CMC which do not re-develop the low-level
jet feature for our area. Hence we have more of a diurnal trend
to the convection Sunday. Hence lowered POPS a bit based on a
blend of these models with the lowest in the morning and POPs
peaking in the late afternoon Sunday.
For Monday, upper level trough axis is overhead and we continued achance
for showers and some storms.
.LONG TERM /MONDAY NIGHT 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 /20Z FRIDAY THROUGH WEDNESDAY/...
VFR conditions are expected for the next 24 hours. Through early
evening sct/bkn fair weather cumulus around 4k ft. Isolated
convection is occurring across central New York but coverage
expected to remain minimal. Late tonight through Saturday morning
a mid level wave will bring mid level clouds into the terminals.
Fog is not expected overnight due to the increasing mid level
clouds and continued dry conditions.
North/northwest winds at 5-10 knots then light and variable overnight
Sat afternoon - Monday...Restrictions possible with showers and
Monday night - Wednesday...VFR.