Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service New York New York
921 am EDT Sat Jul 23 2016

high pressure strengthens over the Tennessee Valley today. A weak
cold front will pass through the region tonight, and then that
high builds east on Sunday. A weak cold front approaches the area
Monday and crosses Monday night. High pressure returns for mid to
late week. A series of weak cold fronts may affect the region
heading into the weekend.


Near term /until 6 PM this evening/...
temperatures are rising faster than earlier forecast under a full
sun. Updated hourly temps, dew points, and sky cover through

High pressure over the Tennessee Valley will impact the region today
with hot temperatures...reaching around 100 degrees across the
NYC/New Jersey Metro area...where a heat advisory remains in effect until
7 PM this evening. Dew point temperatures are forecast to
gradually fall into the lower 60s and perhaps mid to upper 50s
across the NYC/New Jersey Metro area as dryer air mixes down toward the

Meanwhile, a weak cold front approaches from the north during the
day. With the lower atmosphere drying on downsloping west-northwest winds,
pops for tstms were not included with the approach of this front.

West-northwest winds near 15 mph with gusts between 20 and 25 mph will
continue to dry the ground and surface layers.

With rough seas on the ocean this morning, and winds shifting
from a S-SW flow to a west-northwest flow, expect rough conditions on the

There is a borderline moderate to high risk for rip current
development at Atlantic beaches this morning...falling to moderate
this afternoon as southerly swells gradually abate.


Short term /6 PM this evening through Sunday night/...
weak cold front passes through the region tonight. Not expecting
many impacts from its passage, but temperatures slightly cool off
on Sunday as high pressure over the Tennessee Valley continues to build
east. Highs will top off in the upper 80s to low 90s for much of
the cwa, and in the low to mid 90s for NYC/NE New Jersey. With surface
dewpoints in the upper 50s to low 60s, can expect a heat index
generally in the low to mid 90s. It is possible for the heat index
in NYC to be under 95, and a heat advisory may not be needed for

With a weak flow over the region, conditions are ripe for the
development of afternoon sea breezes. Have to monitor potential
for Ambrose jet and locally stronger onshore winds for coastal
portions of NYC.

High pressure moves offshore Sunday evening. Resulting S-SW flow
behind the high will usher a very warm and humid airmass into the
region Sunday night. Lows will only drop into the mid and upper
70s for NYC and surrounding areas, and will be in the upper 60s to
low 70s elsewhere. Some outlying spots could drop into the low
60s. Patchy fog is possible as well outside of NYC.


Long term /Monday through Friday/...
a heat ridge will continue to dominate the the southern 1/2 to
2/3rd's of the country to start the week...with the tri-state region
lying on the northern periphery. Models in fairly good agreement
with a vigorous Pacific shortwave over the northwest US this
morning...phasing with northern stream sun/Mon...and eventually
forming a closed low over northern Ontario/Quebec for mid/late next

An associated shearing shortwave trough approaches the northeast
US on Monday...and swings through the region Monday night. At the
surface...a resultant weak cold front approaches Monday and
crosses Monday night. Ahead of it...with deep mixing and 850 temps
of 20-21c...temps should be able to climb into the mid to upper
90s. The amount of filtering of sunshine is the main uncertainty
due to high/mid clouds from upstream convection. Moisture pooling
dewpoints into the upper 60s/lower 70s will have potential for
heat indices of 100 to 104 for NYC Metro/NE New Jersey/lower hud/and
interior southern CT. There is a low potential for 105 heat
indices. In terms of convection...with building instability and
approaching shortwave energy Monday aft/eve...potential for tstm
development along thermal/pre-frontal trough. Some uncertainty on
strength of shortwave energy...and how it times with peak
heating/instability this far out. That interaction will determine
convective coverage and severity, and will be refined as time
period nears. Cold frontal passage expected Monday night...with
any shower/tstms activity translating eastward and offshore.

High pressure builds into the area on Tuesday, ushering in
only slightly cooler but more so a drier airmass. Highs on
Tuesday will be in the lower to mid 90s, and with surface
dewpoints in the 60s, with heat indices in the mid to upper 90s.

Region will lie between southern heat ridge and earlier mentioned
Ontario/Quebec upper low during the mid to late week period...which
will likely have weak shortwaves rotating through the NE. Very warm
conditions will continue for the mid to late week...with high
generally about 5 degrees above seasonable...well into the 80s to
lower 90s. As moisture slowly increases...potential for aft/eve tstm
activity may increase as the week progresses as well.


Aviation /13z Saturday through Wednesday/...
VFR conditions expected through the taf period. A weak cold front
moves through the region this afternoon. High pressure builds in
tonight into Sunday.

West/west-northwest flow today...with gusts 20-25kt this afternoon. Winds
generally left of 310 mag for NYC/New Jersey Metro terminals...but could
waver just to the right in the afternoon for klga. Coastal sea
breeze development is not expected. Winds and gusts diminish in
the evening...with light NW winds tonight.

Outlook for 12z Sunday through Wednesday...
sun into Sun night...VFR. Afternoon sea breezes for coastal
Monday...mainly VFR, except MVFR or lower possible in scattered
late day/evening thunderstorms.
Tuesday and Wednesday...VFR.


winds currently from the west-SW at 10-15 kt, and will become west-northwest
at 10-15 knots with gusts up to 20 knots by early afternoon. Winds
diminish and may become light/vrb tonight. Afternoon sea breezes
likely on Sunday, and have to monitor potential for locally strong
onshore flow from Sandy Hook to Fire Island Inlet Sunday
afternoon. For now, believe gusts should stay below Small Craft Advisory criteria.

Sub-Small Craft Advisory conditions continue into Sunday night, but there is the
potential for the development of fog.

Potential for marginal sca conditions on Monday aft/eve for ocean
and south coastal nearshore waters with increasing S/SW flow ahead
of a cold front.

Otherwise...sub sca conditions for mid week as high pressure builds


Fire weather...
there is the potential for minimum relative humidity values of 25-30 percent
along with west-northwest winds gusting as high as 25 miles per hour this afternoon for
NYC and coastal portions of NE New Jersey.


dry conditions are expected through Sunday night.

Potential for scattered showers and thunderstorms Monday afternoon
into Monday night, producing heavy downpours. There is potential
for sct diurnal convection late week into weekend.


Okx watches/warnings/advisories...
New York...heat advisory until 7 PM EDT this evening for nyz072>075-176-
New Jersey...heat advisory until 7 PM EDT this evening for njz006-106-108.


near term...gc/mps
short term...mps
long term...Nevada
fire weather...

National Weather Service Glossary of Abbreviations