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Area forecast discussion 
National Weather Service New York New York
740 am EDT Wednesday Jul 23 2014

Synopsis...
as high pressure moves east of the area...a cold front will move
slowly east and pass east of the area on Thursday. High pressure will
follow Friday through Saturday. Waves of low pressure then pass near
the region Sunday into Monday followed by a cold front Monday night
into Tuesday.

&&

Near term /until 6 PM this evening/...
adjusted temperature grids upward slightly this morning to account for a
little quicker heating. Otherwise...forecast on track.

Southwest winds between a departing offshore high pressure system and an
approaching cold front will continue to advect warm moist unstable maritime
tropical air across the area.

Prepare for a hazy...hot and humid Summer day followed by strong to
potentially severe thunderstorms mainly after 3 PM west and north
of NYC.

High temperatures in the lower 90s combined with dew points approaching
70 degrees will produce heat index values in the middle 90s across urban
areas of NYC and northeast New Jersey this afternoon. Because a cold front
is forecast to move south of the area Thursday producing cooler temperatures...we
will not meet the 2 day heat criteria of 95 degrees and therefore
will not issue a heat advisory for NYC.

Because both surface and low level based instability will be increasing along
and ahead of a developing pre frontal trough...there will be an increasing
potential for severe thunderstorms...mainly west and north of New York after 19z.
With a forecast mean storm motion of 230 degrees at 15 kts...can not rule
out training of storms across the same area with an added
potential for isolated flash flooding. Stay tuned.

There is a moderate risk of rip currents...mainly this afternoon
through evening with enhanced sea breeze development.

&&

Short term /6 PM this evening through 6 PM Thursday/...
tonight...showers and thunderstorms will gradually weaken as they move
into a more stable marine environment in place across Long Island
and southern CT.

Thursday...with most models forming a wave of low pressure along
the sagging boundary...look for the redevelopment of a stratiform
rain shield with embedded convection focused across the coastal
area through at least the early afternoon hours. The latest
rainfall amounts might be under estimated.

&&

Long term /Thursday night through Tuesday/...
the period begins with the cold front slowly making its way farther
to our E/se. As such...probability of precipitation will continue diminishing with all areas
dry by late Thursday night. High pressure builds across the area for
Friday...yielding dry weather and temperatures near to a couple degrees
below seasonal norms.

Saturday will see similar temperatures with moisture starting to
increase across the area once again. Zonal flow will be present
aloft...and with a subtle/weak shortwave passing near the
area...continued with slight chance probability of precipitation across western portions of the
County Warning Area. Weak forcing will lead to most spots staying dry though.

The upper-level pattern across the Continental U.S. Really starts to amplify
Saturday night into Sunday...as a Stout shortwave drops out of the
southern Canadian prairies and into the Midwest. As it propagates
around the upper low centered across northern Quebec...a deep trough
will be carved out across the eastern US. This will set the stage
for a period of unsettled weather Sunday into Monday...as
strengthening jet dynamics aloft allow for a couple waves of low
pressure to pass northwest of the area. With increasing southerly
flow/moisture across the area...showers and storms will become more
likely. Still...significant timing differences exist in the passage
of shortwaves/better dynamics aloft...which leads to continued
uncertainty in the timing of more widespread precipitation. Will go
with higher-end chance probability of precipitation Sunday through Monday as a result.

The attendant surface cold front then looks to push through Monday
night into Tuesday...with conditions slowly drying out. There is a
good amount of uncertainty with the frontal timing as well...as the
23/00z European model (ecmwf) shows it stalling across the area with precipitation lingering
across eastern areas into Tuesday night.

&&

Aviation /12z Wednesday through Sunday/...
a cold front approaches from the west today...then crosses the
tri-state tonight.

High confidence in VFR into this afternoon. For now address
thunder potential late this afternoon and tonight with
prob30...for now have timing at NYC metropolitan terminals 23-05z. For
now went MVFR in tempo groups...however with locally heavy
rainfall possible in stronger convection - would not be surprised
if there were brief periods of IFR or lower with any stronger
storms. Have added west-northwest winds 15g30 knots with the thunderstorms for city
terminals.

Light SW flow gives way to seabreeze at all but kswf this
afternoon. For now cannot rule out occasional gusts 20-25 knots at
city/Long Island terminals with seabreeze this afternoon. However
confidence in occurrence/timing is not high enough to include in
the tafs at this time. Winds diminish to under 10 knots in the
evening...veering to the northwest behind the front tonight.

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: timing of changes in wind speed/direction
could be off +/- 2-3 hours. Moderate chance of occasional gusts of
20-25 knots with seabreeze this afternoon. Isolated rain showers/thunderstorm possible 19-23z.

Klga fcster comments: timing of changes in wind speed/direction
could be off +/- 2-3 hours. Moderate chance of occasional gusts of
20-25 knots with seabreeze this afternoon. Scattered rain showers/thunderstorm possible
19-23z.

Kewr fcster comments: timing of changes in wind speed/direction
could be off +/- 2-3 hours. Moderate chance of occasional gusts of
15-20 knots with seabreeze this afternoon. Scattered rain showers/thunderstorm possible
19-23z.

The afternoon kewr haze potential forecast is yellow...which
implies slant range visibility 4-6sm outside of cloud.

Kteb fcster comments: timing of changes in wind speed/direction
could be off +/- 2-3 hours. Low chance of occasional gusts of
15-20 knots with seabreeze this afternoon. Scattered rain showers/thunderstorm possible
19-23z.

Khpn fcster comments: timing of changes in wind speed/direction
could be off +/- 2-3 hours. Low chance of occasional gusts of
15-20 knots with seabreeze this afternoon. Scattered rain showers/thunderstorm possible
19-23z.

Kisp fcster comments: timing of changes in wind speed/direction
could be off +/- 2-3 hours. Moderate chance of occasional gusts of
20-25 knots with seabreeze this afternoon. Isolated rain showers/thunderstorm possible
23-03z.

Outlook for 12z Thursday through Sunday...
Thursday...MVFR or lower conditions in scattered-numerous rain showers/thunderstorms
and possible fog. Best chance in afternoon over eastern terminals.
Thursday night-Saturday morning...VFR.
Saturday afternoon...MVFR or lower possible in isolated rain showers/thunderstorm
mainly northwest of NYC.
Saturday night-Sunday...chance of rain showers/thunderstorms with MVFR or lower
possible.

&&

Marine...
this afternoon through this evening...winds and seas will approach
Small Craft Advisory levels of 25 knots and 5 feet as a cold front
moves east toward the area. Southwest winds will increase to 10 to 15
knots with gusts to 20 knots during this time. Isolated wind gusts
up to 25 knots can not be ruled out. Gusty winds are also possible
in and around thunderstorms mainly from Sandy Hook New Jersey east across the
coastal waters during this time.

Saturday night through Sunday...increasing south winds and building
seas will once again approach Small Craft Advisory levels with the
approach of low pressure.

Otherwise...winds and seas will remain tranquil.

&&

Hydrology...
this afternoon through Thursday...1/4 to 1/2 inch of rain is
forecast with the approach of a cold front. As the precipitable
water content increases to around 2 inches...based on a slow mean
flow of around 15 knots...a few storms might move across th same
area and produce flash flooding with isolated amounts of 1.0 to
1.5 inches.

Waves of low pressure passing near the area Sunday into Monday
have the potential to produce showers and storms capable of heavy
rain. Because significant uncertainty still exists with the timing
and amounts...this heavy rain potential will not be included in
the hazardous weather outlook at this time.

&&

Okx watches/warnings/advisories...
CT...none.
New York...none.
New Jersey...none.
Marine...none.

&&

$$
Synopsis...gc/picca
near term...gc/picca
short term...gc
long term...picca
aviation...maloit
marine...gc/picca
hydrology...gc/picca

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