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Area forecast discussion 
National Weather Service New York New York
938 am EDT Monday Jul 6 2015

Synopsis...
weak high pressure builds offshore today. A warm front approaches
from the southwest tonight...then moves into the tri-state on
Tuesday. A cold front approaches from the west Tuesday
night...then tracks across the area Wednesday into Wednesday
night. The front stalls just to the south on Thursday as a weak
wave of low pressure moves along it. High pressure builds late
week and into next weekend.

&&

Near term /until 6 PM this evening/...
no significant changes to forecast for the middle morning update. Did
lower cloud cover forecast amounts based on observations as most
cirrus is thin. Will take until late this afternoon to thicken. Temperature
forecast seems fine.

Otherwise, a deep layered ridge has its axis slowly cross
the area today. Associated subsidence should be sufficient to keep
things dry. However an isolated shower or sprinkle cannot be
completely ruled out over far west/SW zones this afternoon (hrrr
suggesting central nj).

For highs today a blend of mixing down from 975-875 hpa per BUFKIT
soundings...ecs/met/mav guidance...and NAM 2-meter temperatures
was used. Highs should be near to slightly below normal.

&&

Short term /6 PM this evening through 6 PM Tuesday/...
as deep layered ridge continues to slide offshore...should
moisten low levels sufficiently to warrant slight chance to
slight chance probability of precipitation over mainly the northwest 1/2 of the County Warning Area late tonight
in response to weak low level warm advection. For lows tonight...a
blend of mav/ecs/met guidance and NAM 2-meter temperatures was
used...with values forecast to be around 5 degrees above normal.

Forcing ahead of 700-500 hpa shortwave that moves into the region
late Tuesday warrants likely probability of precipitation over the northwest 1/3 of the County Warning Area and
chance probability of precipitation elsewhere.

Noting forecast convective available potential energy generally of 1000-1500 j/kg - slightly lower
over east Long Island/far southeast CT...showalter indices forecast to be
mainly 0 to 2 indicating low level instability as well warrants
a chance of thunder as well. However with bulk 0-6 km shear of
only 20-25 knots...risk of strong to severe storms is fairly low but
cannot 100 percent be ruled out.

For highs Tuesday used a blend of ecs/met/mav guidance...with NAM
2-meter temperatures and a mix down from 975 to 900 hpa per BUFKIT
soundings. Highs should be a few degrees above normal.

&&

Long term /Tuesday night through Sunday/...
a trough of low pressure lifts to the north Tuesday night and
Wednesday as surface cold front approaches from the west. This front
will be nearly parallel to upper steering flow...so it will be slow
to move through on Wednesday. Model timing is similar with frontal
progression east.

Any leftover showers/thunderstorms Tuesday night depart or weaken. MOS temperatures
are close...and seasonably warm readings are expected.

The cold front remains over the area late Wednesday...and probably
clears the eastern zones by midnight. Will maintain high chance
coverage for now...with scattered showers/thunderstorms Wednesday. Heavy
rain is possible with this slow moving activity...with precipitable water over 2
inches along the front. The concern for heavy rain and training of
cells could lead to at least minor urban/small stream flooding.

Most model solutions forecast the front to settle to the south
Thursday...with some timing differences noted with a wave of low
pressure riding along it. Believe the low passes to the south by
Thursday or Thursday night...with weak high pressure building in
behind it.

Will maintain low chances for showers Thursday into Friday...with a
dry forecast thereafter...or until possibly later Sunday as next
front approaches.

Temperatures should average right around normal levels through the period.
Blended forecast database with new gridded MOS and wpc guidance.

&&

Aviation /14z Monday through Friday/...
weak high pressure will remain over the area today. A warm front
will approach from the southwest tonight.

VFR into early this evening.

With 2nd night of onshore flow and a favorable S-southeast wind direction
ahead of the approaching warm front...IFR conds should develop
mainly after midnight. LIFR expected overnight at kgon/kisp/kbdr
and cannot rule it out for kjfk.

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 direction may vary between 150 and 180
true through the afternoon.

Klga fcster comments: wind direction becomes southeast after 15z.

Kewr fcster comments: wind direction may vary between 150 and 180
true through the afternoon.

The afternoon kewr haze potential forecast is green...which
implies slant range visibility 7sm or greater outside of cloud.

Kteb fcster comments: no unscheduled amendments expected.

Khpn fcster comments: no unscheduled amendments expected.

Kisp fcster comments: no unscheduled amendments expected.

Outlook for 12z Tuesday through Friday...
Tuesday...chance of thunderstorms with MVFR or lower conditions at times...
especially from NYC metropolitan north/west.
Tuesday night...MVFR/IFR conds likely in fog.
Wednesday...chance of thunderstorms with MVFR or lower conditions at times.
Thu-Fri...chance of showers with MVFR or lower conditions
at times.

&&

Marine...
a relaxed pressure gradient over the region will keep winds 10 knots
or less through Tuesday...with the exception of 10-15 knots winds
with occasional gusts to 20 knots in the New York bight region Tuesday
afternoon due to the sea breeze. Seas will remain below Small Craft Advisory
levels through Tuesday as well.

Patchy fog could impact the waters late tonight and Tuesday
morning...bring visibilities to 1 to 3 nm...and possibly below 1
nm at times.

Southerly flow persists ahead of a slow moving cold front Tuesday
night and Wednesday. Then as the front passes nearby and
stalls...winds should lighten as they shift to the northwest briefly.

With a weak pressure gradient in place...the winds may shift back
around to the S/SW Thursday.

As a wave of low pressure moves along the front later Thursday and
Thursday night...relatively light winds may become
variable...depending on the exact track of this low. Overall...sub
Small Craft Advisory conditions are anticipated for the middle to late week period.

Ocean sea forecasts were based on forecast database and new wave
watch output...which seemed quite reasonable. Wind climatology was
the basis for sea/wave forecast for the non ocean waters surrounding
Long Island.

&&

Hydrology...
generally around 1/4 inch or less of rain is expected late
tonight and Tuesday. With highest amounts generally west of the
Hudson River. However...with precipitable waters forecast to be
between 1.75-2 inches...there is the potential for locally heavy
rainfall with any stronger convection. Localized minor flooding
of urban and poor drainage areas would be possible if this were to
occur.

Heavy downpours with slow moving showers/thunderstorms are possible
Wednesday into Wednesday evening. As such...at least localized urban
and poor drainage flooding...with a low chance of flash
flooding...is a possibility Wednesday. Will continue to highlight
this in the severe weather potential statement from Fairfield and Nassau counties on
west...including NYC.

&&

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

&&

$$
Synopsis...maloit/pw
near term...
short term...maloit
long term...precipitable water
aviation...Goodman
marine...maloit/pw
hydrology...maloit/pw

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