Scientific Forecaster Discussion
Area forecast discussion
National Weather Service New York New York
131 am EDT sun Aug 30 2015
high pressure slides offshore and merges with the Bermuda high
into Sunday. A trough of low pressure crosses the area late
Sunday...as the Bermuda high remains offshore into early next
week. A back door cold front moves into the waters on
Tuesday...before lifting back north as a warm front by Wednesday.
High pressure then remains in control through the end of the week.
Near term /through today/...
a northern stream shortwave passes to the north into the
overnight hours...followed by weak northern stream ridging
building in late tonight into far west zones. Given that the best
forcing will be confined to near the U.S.-Canadian border...expect
mainly high and some middle clouds with the passage of the
shortwave...limited to mainly northwest zones.
Forecast is generally on track. Mainly partly cloudy conditions
expected. Otherwise...minor changes to T/TD/winds to better
reflect current conds and trends. Lows should be a few degrees
Short term /tonight through 6 PM Monday/...
the aforementioned shortwave ridging exits to the east by early
afternoon...followed by a northern stream trough which then
crosses the area Sunday afternoon and night. It should be noted
that the European model (ecmwf) is a slow outlier with the timing of the
trough...so used a non-European model (ecmwf) solution for Sunday and Sunday night.
Noting the GFS/CMC-reg/NAM/sref all indicate some showers across
mainly north interior zones mainly Sunday afternoon into Sunday
evening...have introduced slight chance probability of precipitation from roughly Orange
County/western NE New Jersey on NE into north Middlesex County. Appears that
should have sufficient low level cape and low level
instability...with showalter indices down to below 3...to warrant
a slight chance of thunder as well.
Temperatures on Sunday will be a function of how much cloud cover
there is ahead of the trough. With models having 1000-500 relative humidity over
70% over most of the area...have increased cloud cover.
However...low levels could be sufficiently dry to support mixing
to up to 850-825 hpa per BUFKIT soundings...even with cloud cover.
So for now forecasting highs 5-10 degrees above normal...with some
readings around 90 in urban NE New Jersey and possibly NYC. This
consistent with blending a mix down from 950-825 hpa per BUFKIT
soundings with NAM 2-meter temperatures and a blend of
met/ecs/mav guidance. With the relatively dry low levels...heat
indices on Sunday afternoon should peak out in the upper 80s in
urban areas...which is a few degrees below the forecast air
For lows Sunday night...used a blend of mav/ecs/met guidance and
NAM 2-meter temperatures with values forecast to be around 5-10
degrees above normal.
There is a moderate risk for the development of rip currents on
Long term /Monday night through Saturday/...
the main theme of the long term period will be the continuation of
heat and humidity across the region.
Models are in good agreement with the 500 mb pattern across North
America into the middle of the week. An upper level trough will
slide through the area on Monday bringing a weak back door cold front
into the area. There won't be much relief from the heat and
humidity as the boundary will lift back to the north as a warm front
by Wednesday. An upper level ridge moving through eastern Canada will
then merge with the Bermuda high over the Atlantic providing dry
and unseasonably warm weather through Thursday possibly Friday. This will
depend on the timing of the next cold front moving across which is
currently uncertain due to differences that develop in the 500 mb flow
during the latter portion of the week. Could see a few showers or
thunderstorms with the frontal passage which is currently slated for
Friday...followed by dry conditions and cooler but still above
normal temperatures for the weekend.
Highs will generally range in the upper 80s to lower 90s across the
area through much of the week...the exception being Tuesday and Friday/Sat
with the frontal boundaries in/through the area. Heat indices are
expected to be close to the ambient air temperature and are not currently
expected to reach 95 degrees in NYC through Wednesday.
Aviation /06z Sunday through Thursday/...
high pressure slides offshore. A trough of low pressure crosses the
area late Sunday.
VFR conditions are forecast through the taf period.
A west/SW flow 5 to 10 knots is forecast this morning. Sea breezes
develop this afternoon with speeds 10 to 15 knots. A few gusts to 20
knots are possible at NYC terminals as well.
An isolated shower or thunderstorm cannot be ruled out northwest of NYC
terminals this afternoon.
Winds veer to the SW tonight 5 to 10 knots.
Outlook for 06z Monday through Thursday...
Sunday night-Thursday...VFR. Afternoon seabreezes at coastal
terminals each day. SW gusts around 15 knots near city terminals Monday
a relatively relaxed pressure gradient over the region will keep
sustained winds to 15 knots or less and gusts to 20 knots or less
through Sunday night. As a result...absent any significant
swell...seas on the coastal ocean waters will be 4 feet or less and
seas/waves on the sound/Harbor/bays 2 feet or less through Sunday
night as well.
Marginal Small Craft Advisory level seas may clip the outermost portion of anz350
on Monday...otherwise sub-Small Craft Advisory conditions are
expected on all waters Monday through Thursday.
no significant rainfall is expected for the remainder of this
weekend and for the upcoming work week.
with a recent full moon...brief minor inundation is possible
during the times of high tide across the typically vulnerable
coastal locales into the start of the work week.