Scientific Forecaster Discussion
fxus61 kokx 200139
Area forecast discussion
National Weather Service New York New York
939 PM EDT Thu Oct 19 2017
a weak cold frontal passage will occur late tonight. High
pressure will dominate from Friday through Monday, moving
offshore Sunday through Monday. A slow moving frontal system
will then approach the area Tuesday into Tuesday night with a
cold frontal passage by early Wednesday. The front is slow to
depart farther away with a wave of low pressure developing along
it and approaching the area mid into late next week.
Near term /until 6 am Friday morning/...
analysis of surface Theta-E reveals the cold front is beginning
to move across western upstate New York and northwest PA. All high res models
forecast the front to quickly move to the south and east
overnight and move offshore around sunrise. The main upper
level trough will track into northern Quebec tonight so there
will not be any significant change in airmass other than a minor
drop in dew points.
Just a few-sct high thin cirrus tonight behind the upper trough
winds will gradually shift from the SW to the northwest once the front
moves across. Lows tonight fall into the 40s and 50s.
Short term /6 am Friday morning through Friday night/...
high pressure builds back into the region behind the cold
front. Winds will remain from the northwest and gust into the
upper teens and lower 20s. There is a chance that gusts could be
slightly higher than forecast based on the amount of mixing
that occurs. Conditions remain dry. Winds gradually diminish
overnight, becoming light and variable across the interior.
Max temperatures will climb into the upper 60s and lower 70s on
Friday, with lows Friday night falling into the 40s and 50s. A
mav/met/ecs blend was used for the short term temperatures.
Long term /Saturday through Thursday/...
warming trend for the weekend through Monday as the jet stream
remains north of the region with upper level ridging. At this
surface, the dominant feature will be high pressure eventually
moving offshore and the resulting S-SW flow. Mainly clear sky
conditions are expected to continue this weekend.
Clouds increase Monday into Monday night ahead of the next
frontal system. The next chance of rain showers arrives late
Monday night into Tuesday, when a deep upper level trough
approaches from the west.
The trough further deepens Tuesday along the eastern Seaboard
with increasing meridional flow. This will give plentiful
moisture to a developing frontal system at the surface. The
frontal system will be approaching the region Tuesday into
Tuesday night with the region being in the warm sector to the
east of the low with strengthening southerly flow, thereby
increasing warm air advection. Precipitable water increases to
near 1.5 inches from the moisture advection. This is much above
normal for this time of year. According to okx sounding climatology,
it would be above the 90th percentile. Some moderate to heavy
rainfall will be possible.
The cold front moves across Wednesday morning, with a
substantial decrease in precipitable water thereafter to less
than 1 inch. The front slows down and is slow to depart away
from the region. The numerical forecast models show weak low
pressure development along it and the low approaching the region
mid into late next week, with rain shower chances continuing.
Temperatures are expected to be well above normal this weekend
through Tuesday with a gradual decline thereafter. Highs this
weekend through Tuesday are forecast to be well into the 70s
with lows trending to be well into the 50s and near 60 for some
locations along the coast and NYC. The highs are forecast to be
more in the 60s for next Wednesday and next Thursday.
Aviation /02z Friday through Tuesday/...
a weak cold front approaches from the lower Great Lakes tonight
and passes through prior to daybreak. High pressure then builds
in from the west through Friday night.
VFR with only some cirrus through the period.
SW winds around 10 kt early this evening, gradually veer to the
northwest at less than 10 kt through the overnight. Winds will be
right around 310 true during Friday, around 10 kt with frequent
gusts up to 20 kt.
New York Metro enhanced aviation weather support...
Detailed information...including hourly taf wind component fcsts
can be found at:
Kjfk taf comments: occasional gusts to 18 kt possible the next
hour or two.
Klga taf comments: occasional gusts to 18 kt possible the next
hour or two.
Kewr taf comments: no unscheduled amendments expected.
Kteb taf comments: no unscheduled amendments expected.
Khpn taf comments: no unscheduled amendments expected.
Kisp taf comments: no unscheduled amendments expected.
Outlook for 00z Saturday through Tuesday...
Tuesday...MVFR possible in showers. S wind g20-25 kt.
winds east of Fire Island Inlet are close to marginal small
craft levels and this should continue overnight. Seas are also
running right around 5 ft. These conditions will fall below Small Craft Advisory
levels early Friday morning behind a cold front passage.
Elsewhere, winds and seas will generally be below Small Craft
Advisory levels through Friday night. There could be some
nearshore gusts approaching 25 kt Friday afternoon on a
relatively strong northwest flow.
With high pressure dominating, expecting overall a weak enough
pressure gradient to keep conditions below Small Craft Advisory this weekend
through Monday night on the waters. Small Craft Advisory will be probable for
Tuesday ahead of a cold front as southerly winds strengthen the
southerly fetch. Both wind gusts and seas are forecast to meet
Small Craft Advisory thresholds for the ocean for Tuesday and perhaps all waters
a Special Weather Statement has been issued for the entire
region on Friday due to enhanced fire danger. Relative humidity values should
drop to 30 to 35 percent while winds gust 20 to 25 mph,
especially late morning into the afternoon.
no hydrologic problems are expected through Monday night. For
Tuesday through early Wednesday, heavy rain will be possible at
times with potential areas of 1 inch or higher. There is much
uncertainty with exact rainfall amounts. Urban and poor drainage
flooding will be possible.
Marine...Small Craft Advisory until 6 am EDT Friday for anz350-353.
short term...British Columbia