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Area forecast discussion 
National Weather Service New York New York
801 am EDT Thursday Jul 24 2014

Synopsis...
a cold front moves slowly east today. High pressure builds tonight
and Friday. High pressure moves farther offshore on Saturday. A
frontal system approaches Saturday night into Sunday...with an
associated area of low pressure passing to the northwest on
Monday. Following the cold front passage...high pressure builds in
towards mid-week.

&&

Near term /until 6 PM this evening/...
forecast on track. No significant changes.

The cold front moves slowly east today as upper trough approaches
from the west.

Drier air moves in from the northwest...with weak cold air advection noted
behind the front and with the approach of the trough.

Cannot rule out isolated showers per 12km WRF...WRF-nmm...WRF-
arw...hrrr and Canadian. Development of showers remains possible
due to expected weak cape...and vorticity advection in the middle
levels. Noting light showers approaching from the west.

Any shower should be brief.

Assuming mixing up to about 800 mb...high temperatures in the lower 80s seem
reasonable based on 800 mb temperatures settling around 12c per NAM and GFS.
MOS numbers close and accepted.

Cannot rule out late day sea breezes if winds remain sufficiently
weak.

A moderate risk of rip currents exists for eastern Long Island
beaches today with residual southerly swells.

&&

Short term /6 PM this evening through 6 PM Friday/...
upper trough moves across the area and lifts to the north through
this time frame. At the surface...high pressure builds from the west.

Any evening showers give way to dry weather with lower humidity.
A light northerly wind tonight will give way to onshore flow
Friday as the high moves overhead.

MOS temperatures are close...with 50s across the interior...and 60s near
the coast tonight...and upper 70s to lower 80s Friday.

&&

Long term /Friday night through Wednesday/...
as high pressure shifts farther offshore on Saturday...return flow
will help increase moisture across the tri-state.
Additionally...weak 500 mb shortwaves passing near/just north of the
area in zonal flow result in slight/low chance probability of precipitation across the area.

Late Saturday night into Sunday morning...a warm front will lift
across the area as a stronger shortwave progresses to the east
across southern Ontario/Quebec. As a result...chances for showers
and storms will be on the increase...as SW flow aloft increases over
the frontal surface.

As the warm front lifts north and east of the region during the
first half of Sunday...there may be somewhat of a lull in activity
across the area. However...with several shortwaves embedded in the
flow aloft and the increasing moisture present...timing of more
widespread activity is fairly uncertain. 24/00z GFS is more
robust/quicker than 24/00z CMC/European model (ecmwf) with a wave approaching from
the west on Sunday. Believe it is a little too fast...therefore did
not go with likely probability of precipitation everywhere until Sunday night. During this
time...the CMC solution indicates the potential for widespread heavy
rain...as somewhat strung-out cyclogenesis takes place across the
area...and a strong low level jet develops along an axis of higher 500 mb Theta-E.
European model (ecmwf) appears to keep the upper-level jet dynamics a little farther
NW/weaker...resulting in higher quantitative precipitation forecast bypassing the area to the northwest.
Regardless...precipitation appears likely by Sunday night.

Chances for rain gradually diminish Monday into Monday night and
Tuesday...as the associated surface cold front moves through the
area and off to the east. Nonetheless...with the deep upper-level
trough taking hold and cyclonic flow across the region...some
diurnal activity is possible Tuesday.

Following the frontal passage...temperatures look to be a few degrees below
normal Tuesday into Wednesday.

&&

Aviation /12z Thursday through Monday/...
cold front has moved offshore. An upper trough will pass through
today...bringing the chance of isolated rain showers/thunderstorms mainly east of NYC.

Low level moisture is still fairly high...which has resulted in
the formation of patchy MVFR ceilings in the NYC metropolitan. These will
lift/scattered out by 14z. VFR conds then expected all terminals through 06z
Friday...except in any isolated rain showers/thunderstorms later today where they could
briefly drop of MVFR.

Moderate to high confidence in wind forecasts. Low level winds in
the model guidance has trended lower during the day...therefore
do not think there will be much in the way of gusts. In light of
this...the potential for seabreeze development is possible
although highest chance is at kgon/kbdr and possibly kjfk late in the
day. Due to lack of confidence at kjfk...tempo continues.
Otherwise...there is some guidance indicating that wind directions
may back 20-30 degrees at coastal terminals after 18z.

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: southerly winds possible after
19z...otherwise...moderate to high confidence winds remain right
of 310 magnetic. Isolated gusts up to 20 knots through 14z.

Klga fcster comments: moderate to high confidence winds remain
right of 310 magnetic. Isolated gusts up to 20 knots through 14z.

Kewr fcster comments: moderate to high confidence winds remain
right of 310 magnetic. Isolated gusts up to 20 knots through 14z.

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

Kteb fcster comments: isolated gusts up to 20 knots through 14z.

Khpn fcster comments: isolated gusts up to 20 knots through 14z.

Kisp fcster comments: westerly winds possible after 18z. Low chance of southerly
winds after 20z. Isolated gusts up to 20 knots through 15z.

Outlook for 12z Friday through Monday...
Fri-Sat...VFR.
Sat night-Mon...VFR with a chance of rain showers/thunderstorms with MVFR or
lower possible.

&&

Marine...
winds/waves forecast on track. No changes with 12z update.

A cold front slowly moves east of the waters today and tonight. High
pressure builds in Friday. Sub Small Craft Advisory conditions are anticipated today
through Friday.

Relatively tranquil conditions look to exist on the ocean waters
through Saturday. With strengthening S/SW winds Saturday night
into Sunday...seas look to reach Small Craft Advisory criteria during the second
half of the weekend into early next week.

&&

Hydrology...
areas of low pressure passing near the area Sunday into Monday
have the potential to produce showers and storms capable of heavy
rain. Significant uncertainty still exists with timing/amounts
though...so will not outlook in severe weather potential statement at this time.

&&

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

&&

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

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