Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service New York New York
400 am EDT sun may 24 2015

Synopsis...
Bermuda high pressure persists through midweek. The high then
moves farther out into the Atlantic and weakens across the local
region with multiple lows passing from the Great Lakes into
southeast Canada middle through late week. There will be a weakening
cold front entering Wednesday night and stalling within the
vicinity on Thursday while further weakening.

&&

Near term /until 6 PM this evening/...
aloft...the jet stream will be pushing north during the
day with an incoming longwave ridge from the west. The ridging
will promote subsidence...keeping mostly sunny conditions during
the day today.

At the surface...high pressure will set up offshore
today...essentially becoming a persistent Bermuda high. The
southwest flow across the region will remain and likely increase
with adiabatic mixing up to 875 to 900 mb. Gusts will be in the
15 to 20 knots range. The sea breeze will be more limited due to
stronger SW boundary layer flow.

The 850 mb temperatures have already been increasing and are expected to
continue in this trend through the day. The mixing will allow for
remarkably warmer temperatures compared to yesterday. Used a
met/ekd blend of temperatures to reflect the warmer side of
guidance which verified pretty well the previous day with high
temperatures.

&&

Short term /6 PM this evening through 6 PM Monday/...
for tonight...the subsidence from the ridge will still be
prominent with mostly clear skies with a strong Bermuda high in
place. The southwest flow will continue...moderating temperatures
across Long Island. Used a blend of mav and ece for low
temperatures...again siding with a relatively warmer solution.

For Monday...the 850mb temperatures increase a few
degrees...overall exhibiting a steady rising trend compared to the
previous day. Likewise...expecting high temperatures near the surface to
be a few degrees warmer than the previous day. However...at the
immediate coastline...the temperatures are forecast to be nearly the same
as the previous day. The southwest flow continues with strong high
pressure offshore.

More clouds are expected but weather is expected to remain dry
with a warm front to the north of the region.

&&

Long term /Monday night through Saturday/...
the ridge and surface high remain in place Monday night through
Wednesday night with a southwesterly flow keeping a warm and humid
air mass in place. For Tuesday and Wednesday afternoons and into
the evenings each day there will be a low chance for showers and
thunderstorms around the periphery of the ridge as weak surface
troughs develop. The air mass showers and thunderstorms will be
diurnally driven with build up of cape and therefore instability.
If the high and ridge are stronger and remain in place...the
inland areas may remain dry. Farther east is more stable while
farther west will be more unstable as that is where warmer air
will reside.

As a shortwave moves into the ridge Wednesday night into Thursday
afternoon and weakens Friday there will be better chances of
precipitation...and farther to the south and east. However...not
highly confident that the ridge weakens significantly and kept
probability of precipitation at chance.

Finally with increasing low level moisture...with dew points
rising...and a south to southwest flow there will be the increasing
likelihood of stratus and fog developing Wednesday night and again
Thursday night. May be more of a stratus deck across Long Island and
possibly coastal Connecticut with the flow more southwesterly than
south.

&&

Aviation /08z Sunday through Thursday/...
high pressure off of the middle Atlantic coast will slowly move eastward
through the day today.

VFR through the taf period.

A light synoptic SW flow increases again after sunrise. Gusts to
around 20 knots...or in the lower 20s...are expected to develop and
this will cause some uncertainty in whether true seabreeze
directions at kjfk/klga/kbdr/kgon/kisp can be realized in the
afternoon. Highest likelihood for true seabreeze is kjfk.

Winds lighten after sunset to under 10 kts.

Outlook for 06z Monday through Thursday...
tonight-Monday night...VFR. SW winds g15-20kt possible Monday
afternoon.
Tuesday-Thursday...MVFR or lower possible in stratus and/or fog
late at night/morning...otherwise VFR. Low chance rain showers/thunderstorm northwest of NYC
metropolitan each afternoon. Coastal sea breezes likely each afternoon...with
S-SW winds g15-20kt possible.

&&

Marine...
an area of high pressure will remain east of the waters
through the middle week period. Persistent southwest flow will prevail.
Winds at times could approach 20 to 25 kts over the ocean waters...
especially during each afternoon. Seas gradually build to 5 feet
over the ocean waters...probably beginning late Monday or Monday
night. The local non ocean waters should remain just below Small Craft Advisory
criteria through the middle week period.

Fog/poor visibilities will become more likely by middle week.

&&

Hydrology...
no significant widespread rain expected through the forecast
period.

&&

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

&&

$$
Synopsis...jm
near term...jm
short term...jm
long term...jm/met
aviation...precipitable water
marine...precipitable water
fire weather...
hydrology...jm

National Weather Service Glossary of Abbreviations