Scientific Forecaster Discussion
Area forecast discussion
National Weather Service New York New York
1031 am EDT Thursday Oct 8 2015
high pressure passes to the north and east today. A warm front
lifts to our north tonight into Friday morning...followed by a
cold front crossing the tri-state Friday afternoon and evening.
High pressure builds in from the west from late Friday night
through the weekend. A cold front approaches from the west Monday
and Monday night...then moves across the region on Tuesday. High
pressure then builds in for the middle of next week.
Near term /until 6 PM this evening/...
made some minor adjustments based on initial conditions.
However... there is some concern with the extent of the cloud
cover across Li and NYC metropolitan based on trends in latest Sat
imagery. Model time height cross sections continue to show
moisture pooling beneath inversion at 80h. Thus...have increased
the amount of cloud cover across these locations with mainly
partly sunny conditions anticipated through this afternoon.
Northern zones are expected to remain mostly sunny.
Otherwise...high pressure passes to the north today with NE winds
becoming southerly by this after.
For highs today used a blend of mav/ecs/met guidance...NAM
2-meter temperatures and a mix down from 925-900 hpa per BUFKIT
soundings. Highs should be slightly above normal.
Short term /6 PM this evening through Friday night/...
850 hpa warm front pushes to the NE tonight...with increasing
cloud cover. However...relatively dry low levels should lead to a
dry passage. Also...low level warm advection should lead to a
non- diurnal temperature trend...with temperatures holding steady
or slowly rising after midnight. Lows tonight should be around
5-10 degrees above normal and should occur during the evening
hours at most locations.
Increase probability of precipitation to categorical Friday afternoon/evening (highest northwest
zones Friday afternoon and southeast zones Friday evening) as should see
a solid line of showers ahead of a passing 700-500 hpa shortwave
and 850 hpa cold front. With showalter indices forecast to be
around 0 and the forcing of being in the right rear quadrant of
a 100kt 300 hpa jet...have continued with a slight a chance of
thunder ahead of the front Friday afternoon/evening as well.
Still some disagreement over amount of surface based cape...with
NAM a few hundred j/kg higher than GFS/ECMWF...but that will only
serve as a limit on strength not occurrence. Decrease probability of precipitation very
rapidly from northwest to southeast Friday evening...with the front well to the
S/east by 6z...and limited to no Post-frontal precipitation being
forecasted by all models (cmc is most pronounced with any Post
Trended highs towards warmer guidance on Friday...with a late day
frontal passage allowing for full impact of strong pre-frontal
warm surge. Highs were based on a blend of met/ecs/mav guidance
NAM 2-meter temperatures and a mix down from 975-900 hpa per
BUFKIT soundings. For now kept temperatures in NE New Jersey/north NYC below
80...but would not be surprised if a few places reached or went
just above that threshold. In general highs Friday should be
around 5-10 degrees above normal...with most locations closer to
10 than 5 degrees above normal.
For lows Friday night...a blend of mav/met/ecs guidance and NAM
2-meter temperatures was used...with values around 5 degrees above
Long term /Saturday through Wednesday/...
dry and cool conditions expected on Saturday as high pressure builds
into the region. High temperatures on Saturday will be in the lower
60s. As the high builds overhead Saturday night into
Sunday...temperatures will fall into the 40s across most locations.
The high then moves offshore Sunday allowing temperatures to warm up
into the middle and upper 60s...which is closer to normals.
Dry conditions continue on Monday with daytime temperatures in the
upper 60s to lower 70s and overnight temperatures in the low to middle
50s. A cold front will approach the area from the west Monday night
into Tuesday. Models continue to show limited moisture with the
frontal passage. For now...will continue with slight chance probability of precipitation
for Tuesday. The front should move east of the region Tuesday
night and offshore by Wednesday. High pressure builds back in from
the west on Wednesday.
As for temperatures...high temperatures on Tuesday should be in the
upper 60s to lower 70s...with overnight temperatures in the low 50s
along the coast and upper 40s inland. High temperatures on Wednesday
should be in the low to middle 60s.
Aviation /15z Thursday through Monday/...
high pressure builds to the north this afternoon and then slides off the
New England coast tonight.
VFR through at least 06z...then possible stratus/fog developing
after 06z outside metropolitan terminals. Tonight will only be the first
night of onshore flow...leading to uncertainty in how widespread
stratus will be.
North-NE winds 5 to 10 knots becoming S-southeast in the afternoon. Seabreezes
possible at kjfk/kgon/kbdr after 18z...but not confident directions
will be true seabreeze directions.
New York metropolitan enhanced aviation weather support...
Detailed information...including hourly taf wind component forecasts
can be found at:
http:/www.Erh.NOAA.Gov/zny/n90 (lower case)
Kjfk fcster comments: wind directions may range 170-180 after 18z.
Klga fcster comments: timing of southeast winds could be +/- 1-2 hours.
Kewr fcster comments: timing of southeast winds could be +/- 1-2 hours.
The afternoon kewr haze potential forecast is green...which
implies slant range visibility 7sm or greater outside of cloud.
Kteb fcster comments: timing of southeast winds could be +/- 1-2 hours.
Khpn fcster comments: timing of southeast winds could be +/- 1-2 hours.
Kisp fcster comments: timing of southeast winds could be +/- 1-2 hours.
Outlook for 12z Friday through Monday...
Friday...showers becmg likely west-east in the afternoon with a slight chance
of a thunderstorm. MVFR likely...brief local IFR possible. Cold frontal passage in
a relaxed pressure gradient over the region will keep winds to 10
knots or less through tonight. The pressure gradient increases
Friday...and remains moderate Friday night. There is the potential
for gusts to 25-30 knots over the waters Friday afternoon and night.
The best chance is over the coastal ocean waters...and the lowest
possibility is over New York Harbor and west Long Island Sound. For
now...the confidence in occurrence is less than 80 percent...so
have held off on issuing an Small Craft Advisory for now. Noting wavewatch
typically runs 1-2 feet high in SW flow regimes...undercut by the
same Friday into Friday night. So for now have maximum seas of 5
feet only on the far eastern coastal ocean zone Friday afternoon/night.
On Saturday morning...wind gusts between 20 to 25 knots are possible
across the ocean waters. Wind gusts and seas should diminish to
below Small Craft Advisory levels by Saturday afternoon as high pressure builds
across the area waters. Below Small Craft Advisory conditions continue on all waters
on Sunday and Monday.
it should be dry through tonight. 1/10-3/10 of an inch is forecast
from Friday into Friday evening...with locally higher amounts
possible in areas experiencing stronger convection. Areas
receiving locally heavy rainfall could have ponding of water on
roadways...mainly in known poor drainage areas.
Dry weather from this weekend into early next week.