Scientific Forecaster Discussion
Area forecast discussion
National Weather Service New York New York
1051 PM EDT Tuesday Sep 1 2015
weak high pressure builds in through tonight. A trough of low
pressure develops across New England into northern New Jersey
Wednesday and remains in the vicinity Wednesday night. A cold
front approaches from the north Thursday...moving through the tri-
state Thursday night. High pressure builds in from the north for
the weekend into early next week.
Near term /until 6 am Wednesday morning/...
forecast is on track. Only minor adjustments needed to hourly
T/dew point to account for current conditions and trends.
An upper ridge and surface high pressure remain just to the
west...through upstate New York into the Ohio Valley...this evening
into late tonight. The upper ridge weakens as a shortwave associated
with convection across Illinois and Indiana moves east into the
Ohio Valley by 12z Wednesday. With mainly dry conditions expect
mostly clear skies. There will be some high cloudiness moving in
late at night as the shortwave approaches. Wind will be light and
some patchy fog in outlying areas will be possible.
Short term /6 am Wednesday morning through Wednesday night/...
as the shortwave moves into the middle Atlantic Wednesday the upper
ridge will rebuild farther to the west through Wednesday night.
This will allow a trough to the east to begin to dig into the
northeastern states. Meanwhile at the surface high pressure
weakens over the Ohio Valley and a surface trough develops across
New England into northern New Jersey into southeastern
Pennsylvania. The area remains dry Wednesday and Wednesday night
with no triggers or upper support present. Another shortwave does
approach in the northwest upper flow toward 12z Thursday.
Long term /Thursday through Tuesday/...
gradually increasing drought and fire weather concerns through the
A weak northern stream shortwave slides through the region late
Thursday/Thursday night...while a strong northern stream upper low digs
through the Canadian Maritimes. Models in good agreement with upper
ridging building into the region for the weekend...before gradually
flattening early to middle next week.
Late Summer heat and humidity will continue on Thursday. A Canadian cold
front approaches from the north late Thursday/Thursday evening as shortwave energy
digs southeast through the Canadian Maritimes. This will bring potential of
isolated/scattered showers/thunderstorms late Thursday into Thursday night as the front
sags south. Daytime highs will be in the lower 90s Thursday with heat
index values in the lower 90s across NYC and urban NE New Jersey.
Canadian high pressure builds south-southwest across the region Friday into
Saturday. This will advect a cooler and drier Canadian maritime
airmass into the region for Friday and Sat. Although humidity levels
should be in the 50s...gusty east winds on Friday may pose a
enhanced concern for spread of brush fires due to 400-500 kbdi
values and available fine fuels. Along the coast...potential exists
for a high rip current risk Friday into Sat. Highs are still expected
to run near seasonable...upper 70s/lower 80s.
Dry conditions are expected through early next week as high pressure
sinks southeast of the region. This will also spell a steady moderation in
humidity and late Summer heat through early next week.
Aviation /03z Wednesday through Sunday/...
VFR with high pressure over the region. Light and variable winds
will become southerly Wednesday with speeds 5-10 knots. The winds
could occasionally reach a few kts higher than forecast for
A period of occasional MVFR visibilities is forecast 08z-12z Wednesday
at kswf/khpn/kgon in fog. This could occur 1-2 hours earlier than
forecast. The MVFR fog will be possible for kteb and kbdr as
Outlook for 00z Thursday through Sunday...
Thursday-Thursday night...mainly VFR. MVFR or below possible with
a chance of showers/thunderstorms. Afternoon sea breezes
Friday...a slight chance of showers and thunderstorms early on
with MVFR or below possible. Otherwise VFR. East-northeast winds g15-20kt.
a weak pressure gradient will be across the forecast waters tonight
through Wednesday night. High pressure will be across the region
with a weak surface trough developing along the coast Wednesday
afternoon and remaining into Wednesday night. Wind and seas will
remain below small craft levels into Wednesday night.
Sub Small Craft Advisory conditions expected Thursday ahead of an approaching cold front.
The next chance for Small Craft Advisory level winds and seas is
Friday following the passage of a cold front. Potential exists for
easterly winds of 15 to 20 knots with gust 25 knots and ocean seas
building to 5 to 6 feet. Small Craft Advisory gusts possible on Li sound and nearshore
Winds and seas appear to gradually subside Friday night into Sat...with
sub Small Craft Advisory conds likely for the end of the weekend.
dry through Wednesday night.
No widespread significant rainfall is forecast through next weekend.
Drought will continue to develop region wide...but especially across
Long Island and southern CT through the period with no significant
widespread rainfall in the forecast.