Scientific Forecaster Discussion

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Area forecast discussion 
National Weather Service New York New York
843 PM EDT Thursday Apr 17 2014

Synopsis...
high pressure slowly retreats to the northeast through Friday
night. Another area of high pressure system move slowly southeast
across the region Saturday through Monday. Low pressure will move
toward the area Tuesday then east of the area Wednesday followed
by another high pressure system.

&&

Near term /until 6 am Friday morning/...
forecast on track this evening and made just made minor edits to
the temperatures and dew points. Still monitoring the potential for a
stratus layer to move onshore this evening and overspread coastal
areas. Have moved the timing of this back a couple hours as
current laps soundings are much drier than some of the forecast
soundings. Thinking if the cloud cover occurs...it will take
longer to overcome the dry air. Still unsure exactly how far
inland the lower clouds will get. But also still expecting higher
level clouds to move in from the west so sky cover forecast
reflects that as well.

Still thinking that temperatures will remain above
freezing...at least where the frost/freeze program has started. So
will keep the frost advisories that are already in effect.

There is a chance that frost may not even develop with the cloud
cover...however if clouds do not move in...or we get breaks in the
clouds frost will be possible.

Otherwise...expect a dry night with lows falling into the middle and
upper 30s. Of course temperatures may have to be nudged down a bit
of clouds take longer to move in. Went slightly above a mav/met
blend for temperatures tonight.

&&

Short term /6 am Friday morning through Friday night/...
weak high pressure will remain over the region Friday and Friday
night.

A northern stream shortwave will pass north of the region on Friday
and given lack of low level moisture...only expect to see increase
in middle-high clouds on Friday ahead of the shortwave.

Friday night will remain dry...however skies will remain mostly
cloudy with the shortwave passing nearby.

Mav/met guidance in good agreement and used. Temperatures on Friday
will reach the upper 40s and 50s...while Friday night falls into the
30s and lower 40s.

&&

Long term /Saturday through Thursday/...
dry weather is forecast Saturday through early Tuesday as a slow
moving Canadian high pressure system moves slowly across the region.

For Saturday...with the approach of high pressure and the advection
of strong subsidence...there will be an enhanced risk of fire spread
under full sun as humidities decrease to less than 30 percent and northwest
winds increase to 10-15 miles per hour during the afternoon. Temperatures are
forecast near normal values in the 60s.

For Sunday...a light onshore wind flow will develop as high pressure
moves off the coast causing afternoon high temperatures mainly in the 50s
across Long Island and southern CT...with low 60s north and west of
NYC.

Forecast models show a digging amplifying upper level short wave
approaching Wednesday causing cyclogenesis near the local area with
our next chance of rain...Tuesday afternoon through Wednesday. At
this time...this appears to mainly be a light to possibly moderate
rainfall of 1/4-1/2 inch.

&&

Aviation /00z Friday through Tuesday/...
high pressure centered over the Canadian Maritimes and extending
down the eastern Seaboard will slowly move east while weakening
through Friday.

VFR to start...but potential for MVFR ceilings becomes the challenge
tonight. Before the loss of visible Sat...strato cumulus over the Atlantic
was eroding. Some 18z model guidance has too much low level
moisture at 00z compared to Sat imagery and soundings.
However...since an Ely flow is expected to prevail
overnight...moisture is expected to become trapped beneath a
subsidence inversion. Question is timing and extent. Some of the
high res model data suggests a patch of MVFR ceilings moves across Li and
NYC terminals between 02z and 06z with a more widespread area of
stratus moving onshore between 07z and 09z. This continued to
support the previous forecast thinking...although have extended
the stratus into klga and included tempo's at kewr/kteb with lower
confidence here. The MVFR ceilings are expected to scattered out middle- late
Friday morning.

VFR conds expected thereafter with sea breezes likely at coastal
terminals during the afternoon.

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: gusts 20-25kt possible after 18z. Timing of
MVFR ceilings may be +/- 1-2 hours. IFR ceilings possible between 09z and
13z Friday.

Klga fcster comments: timing of MVFR ceilings may be +/- 1-2 hours.
Wind direction may be 30-40 degrees right of forecast by late afternoon.

Kewr fcster comments: extent of MVFR ceilings will need to be
monitored overnight with amendments possible for inclusion in
prevailing group. Could impact morning push.

Kteb fcster comments: extent of MVFR ceilings will need to be
monitored overnight with amendments possible for inclusion in
prevailing group. Could impact morning push.

Khpn fcster comments: timing of MVFR ceilings may be +/- 1-2 hours.

Kisp fcster comments: timing of MVFR ceilings may be +/- 1-2 hours. IFR
ceilings possible between 09z and 13z Friday.

Outlook for 00z Saturday through Tuesday...
Friday night-Monday night...VFR.
Tuesday/Tuesday night...MVFR possible with showers...cold frontal passage.

&&

Marine...
a Small Craft Advisory remains in effect for the ocean waters where
gusts are reaching 25 knots and seas are around 6-7 feet. This small
craft remains in effect through Friday. Sub-Small Craft Advisory conditions are
expected on the remainder of the waters.

Winds and seas are forecast to fall below Small Craft Advisory levels Friday
night...however some lingering 5 feet seas may remain for the first
part of the night...especially across the eastern waters.

Winds and seas are forecast to remain below Small Craft Advisory
levels Saturday through Monday as high pressure moves slowly across
the coastal water.

South winds and seas will increase with the approach of low pressure
on Tuesday and possibly meet Small Craft Advisory levels Tuesday
afternoon. After a brief lull Tuesday night..northwest winds may
increase to Small Craft Advisory levels on Wednesday.

&&

Hydrology...
dry weather is forecast through Tuesday morning. There is a
chance for 1/4 - 1/2 inch rainfall associated with a low pressure
system Tuesday afternoon through the day Wednesday.



Note...minor flooding continues along the Connecticut River. For
additional information...please refer to the latest flood warnings
from National Weather Service Taunton Massachusetts.

&&

Okx watches/warnings/advisories...
CT...frost advisory from 1 am to 9 am EDT Friday for ctz009>012.
New York...frost advisory from 1 am to 9 am EDT Friday for nyz069>071-
078>081-177-179.
New Jersey...frost advisory from 1 am to 9 am EDT Friday for njz004-103>108.
Marine...Small Craft Advisory until 6 PM EDT Friday for anz350-353-355.

&&

$$
Synopsis...BC/gc
near term...BC/ln
short term...British Columbia
long term...gc
aviation...
marine...BC/gc
hydrology...BC/gc